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Sample records for apatite fission track

  1. Naturally etched tracks in apatites and the correction of fission track dating

    CERN Document Server

    Tien, J L

    1999-01-01

    Naturally etched tracks have been found in apatites from the rapid cooled, high-level Kunon pluton in the Zhangzhou Igneous Complex, SE China. This is manifested by the fact that the apatite fission track (FT) age derived from conventional counting of spontaneous and induced tracks yields a result of 140.6+-6.5 Ma, which is much older than the ages determined using other methods on different minerals from the same rock. When tracks are observed after etching the polished inner sections of the apatite grains, the naturally etched tracks characterized by having hazy boundaries can be distinguished from the normal tracks with sharp boundaries. The age obtained by omitting these fading-resistant hazy tracks, 76.5+-4.0 Ma, indicates the time of the Kunon pluton cooling down to approx 100 deg. C. The corrected peak age (73.8 Ma) is consistent with the other apatite FT peak ages (79.2 to 70.2 Ma) of the nearly contemporaneous plutons in the same igneous complex.

  2. Meso-Cenozoic tectonics of the Central Kyrgyz Tien Shan (Central Asia), based on apatite fission track thermochronology.

    OpenAIRE

    Glorie, Stijn

    2008-01-01

    Apatite fission track thermochronology on the Kyrgyz Tien Shan basement revealed a polyphased thermal history of the study-area. We interpret the Mesozoic and Cenozoic cooling-events as periods of tectonic reactivation.

  3. Mesozoic-Cenozoic thermal history of Turpan-Hami Basin: apatite fission track constraints

    Institute of Scientific and Technical Information of China (English)

    ZHU Wenbin; WAN Jinglin; SHU Liangshu; SUN Yan; GUO Jichun; WANG Feng

    2005-01-01

    Apatite fission track dating is carried out on nine samples collected from the central part (Lianmuqin section) and from both northern and southern margins of Turpan-Hami Basin. The fission-track ages of seven Jurassic samples are distinctly younger than depositional ages. In contrast, the fission-track ages of two Cretaceous samples are older than, or as old as depositional ages. These observations indicate that the Jurassic samples have been annealed or partially annealed, whereas the Cretaceous samples have not been annealed.The further thermal modelling results show that Turpan-Hami Basin experienced a Late Cretaceous period (120-100 Ma) of tectonic uplift with rapid cooling and exhumation of sediments. The samples underwent a Cenozoic period of reburial and re-heating and were exhumed again at 10-8 Ma.

  4. A re-evaluation of geological timescale benchmarks and temperature sensitivity of fission-track annealing in apatites

    Science.gov (United States)

    Luijendijk, Elco; Andriessen, Paul

    2016-04-01

    Current models of the temperature sensitivity of fission track annealing in apatites have been calibrated using fission track data from boreholes, with the assumption that these samples are currently at maximum burial depth and temperatures. The most detailed data-set comes from boreholes located in the Otway basin, Australia. However, several lines of evidence suggest that these samples are not at their maximum burial depth and temperature and consequently the cooling temperature of the apatite fission track thermochronometer would then be higher than previously assumed. Significant late Cenozoic exhumation in the Otway Basin was suggested by earlier studies that document a major late-Miocene erosional unconformity, folding and trusting of underlying sediments and elevated strandlines along the coast. In addition, anomalously young apatite (U-Th)/He ages in several boreholes in the basin suggest that the basin's sediments have been exhumed and cooled in the late Cenozoic. We explore the effects of late Cenozoic exhumation on fission track data in the Otway basin using a 1D model of burial and thermal history. We show that simulating several 100s of meters of exhumation in the basin results in significant misfit between current annealing models and observed fission track data. The additional exhumation reconciles the Otway basin data with a second detailed fission track dataset from boreholes in Southern Texas with a well-constrained thermal and burial history. We combine vitrinite reflectance data and U-Th/He data from the Otway basin to recalibrate the burial history of the Otway basin. Subsequently we combine the new thermal history of the Otway basin with the Southern Texas dataset to recalibrate the fission track annealing algorithm. The results suggest that fission-track annealing in apatites is underestimated by approximately 20°C by current annealing models, with significant implications for studies that use apatite fission track thermochronology to

  5. Apatite fission track dating evidence for tectonic move-ment of Yarlung Zangbo Thrust Zone

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Fission track geological chronology is an effective method of study on tectonic movement of fault zone.Apatite fission track (AFT) dating analyses of 9-apatite and 4-zircon samples collected from Lhasa to Langkazi,-70-kin-long in SN provide an understanding of the age and the uplifting of both sides of the Yarlung Zangbo Thrust Zone (YZTZ) in this work. The AFT ages range from -37 to 14 Ma, indicating the time of major tectono-thermal events,i.e. the continent-continent collision along the YZTZ. Based on the relationship between the AFT ages and the sample elevations, there were two tectonic active periods: -37-20Ma and 20}-14 Ma. In the first period the tectonic event did not bring on differential uplifting. Rapid differential uplifting with rapid cooling, resulting from thrusting, took place in the second period. The vertical displacement was -1020 m and total -2.9 km of overburden has been removed from the present-day surface since cooling below -ll0℃ began. The maximum cooling and denudation occurred at a rate of -7℃/Ma and -207 m/Ma respectively since -14 Ma. The zircon fission track analysis demonstrates that the temperature of tectono-thermal events did not exceed 310℃.``

  6. FISSION TRACK DATA OF APATITE AND ZIRCON FROM LOWER YANGTZE AREA

    Institute of Scientific and Technical Information of China (English)

    LiCheng; WangLiangshu; ShiXiaobin

    1999-01-01

    Fission-track analysis has been an available method to learn tectonic-thermal evolution and geothermal history[1-4], and it provides some information for the complex tectonic evolution in the Lower Yangtze area. No fission-track analyses in the area are published so far. This paper briefly presents the results of fission-track analyzed in the Lower Yangtze area.

  7. Constraining the stepwise migration of the eastern Tibetan Plateau margin by apatite fission track thermochronology

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Granites sampled from Garzê-Litang thrust, Longmen Shan thrust, Garzê and Litang strike-slip faults in the eastern Tibetan Plateau have been analyzed with apatite fission track thermochronological method in this study. The measured fission track apparent ages, combined with the simulated annealing mod- eling of the thermal history, have been used to reconstruct the thermal evolutionary histories of the samples and interpret the active history of the thrusts and faults in these areas. Thermal history mod- eling shows that earlier tectonic cooling occurred in the Garzê-Litang thrust in Miocene (~20―16 Ma) whereas the later cooling occurred mainly in the Longmen Shan thrust since ~5 Ma. Our study sug- gests that the margin of eastern Tibetan Plateau was extended by stages: through strike-slip faults deformations and related thrusts, the upper crust formed the Garzê-Litang margin in the Miocene epoch and then moved to the Longmen Shan margin since ~5 Ma. During this process, the deformations of different phases in the eastern Tibetan Plateau were absorbed by the thrusts within them and conse- quently the tectonic events of long-distance slip and extrusion up to hundreds of kilometers have not been found.

  8. Constraining the stepwise migration of the eastern Tibetan Plateau margin by apatite fission track thermochronology

    Institute of Scientific and Technical Information of China (English)

    LAI QingZhou; DING Lin; WANG HongWei; YUE YaHui; CAI FuLong

    2007-01-01

    Granites sampled from Garzê-Litang thrust, Longmen Shan thrust, Garzê and Litang strike-slip faults in the eastern Tibetan Plateau have been analyzed with apatite fission track thermochronological method in this study. The measured fission track apparent ages, combined with the simulated annealing modeling of the thermal history, have been used to reconstruct the thermal evolutionary histories of the samples and interpret the active history of the thrusts and faults in these areas. Thermal history modeling shows that earlier tectonic cooling occurred in the Garzê-Litang thrust in Miocene (~20―16 Ma) whereas the later cooling occurred mainly in the Longmen Shan thrust since ~5 Ma. Our study suggests that the margin of eastern Tibetan Plateau was extended by stages: through strike-slip faults deformations and related thrusts, the upper crust formed the Garzê-Litang margin in the Miocene epoch and then moved to the Longmen Shan margin since ~5 Ma. During this process, the deformations of different phases in the eastern Tibetan Plateau were absorbed by the thrusts within them and consequently the tectonic events of long-distance slip and extrusion up to hundreds of kilometers have not been found.

  9. Long-term exhumation history of the Inner Mongolian Plateau constrained by apatite fission track analysis

    Science.gov (United States)

    Li, Ke; Jolivet, Marc; Zhang, Zhicheng; Li, Jianfeng; Tang, Wenhao

    2016-01-01

    The Inner Mongolian Plateau, along the southeastern flank of the wider Mongolian Plateau, is a vast undulating surface ranging in elevation between 900 and 1500 m above sea level. The peculiar topography of this area is assumed to be closely related to its complex tectono-thermal evolution since Late Paleozoic. The lithospheric structure of the Plateau includes three continental blocks: the Mandula and the Bart Obo blocks form the southern margin of the Central Asian Orogenic Belt in that area, and to the south, the Plateau includes the northern margin of the North China Craton. Apatite fission track (AFT) ages and track length distributions from 13 basement outcrops situated in the main tectonic blocks forming the Inner Mongolian Plateau were determined in order to reconstruct its denudation history. The thermal histories inferred from these data imply multi-phased, differential exhumation/burying processes from the Late Paleozoic to the Early Cretaceous. This complex thermal history is largely related to the Early/Middle Triassic closure of the Paleo-Asian Ocean, the Jurassic closure of the Mongol-Okhotsk Ocean, and the Early Cretaceous orogenic collapse of the Mongol-Okhotsk belt. Finally, since Late Cretaceous, no further major tectonic movement occurred and the Inner Mongolian Plateau has been largely peneplained.

  10. Thermotectonic evolution of the Ukrainian Donbas Foldbelt: evidence from zircon and apatite fission track data

    Science.gov (United States)

    Spiegel, C.; Sachsenhofer, R. F.; Privalov, V. A.; Zhykalyak, M. V.; Panova, E. A.

    2004-05-01

    The Donbas Foldbelt forms part of a large Devonian rift cross-cutting the southern part of the Eastern European Craton. It comprises a 20-km-thick Devonian and Carboniferous sedimentary succession. Maximum burial occurred during early Permian time and was followed by a major exhumation phase. In this study we use zircon and apatite fission track dating to reconstruct the post-depositional thermal evolution of the inverted basin. Modelling of the fission track data, combined with modelling of vitrinite reflectance data, reveals that large parts of the basin were affected by a Permo-Triassic (˜250 Ma) heat flow event, which was presumably related to Permo-Triassic andesitic magmatism. This Permo-Triassic thermal event was predicted by previous modelling of vitrinite reflectance data, but only the fission track data indicates its wide areal distribution. Probably large parts of the southern margin of the Eastern European Craton were affected by this event. Whereas rocks west of the city of Donetsk (Krasnoarmeisk Monocline) experienced Permo-Triassic temperatures in the range of 90-105 °C, rocks northwest of Donetsk were heated to up to more than 240 °C. Jurassic temperatures northeast of Donetsk were in the order of 90-100 °C. These relatively high temperatures imply that a significant part of the Carboniferous sequence became eroded only during early Cretaceous times and/or that the Jurassic heat flow was significantly increased (˜90 mW/m 2). Elevated heat flows may be related to Jurassic magmatic activity. Sediments in the southern Donbas Foldbelt (Yuzhno-Donbassky region) and the westernmost Krasnoarmeisk Monocline record cooling below 60 °C during Jurassic times, whereas samples northeast of Donetsk cooled below 60 °C during Cretaceous times. A correlation between this last cooling and the present-day depths of the samples suggests that the main episode of folding along the South Syncline and the South Anticline pre-dates Cretaceous cooling.

  11. Apatite fission track dating evidence on the tectonization of Gangdese block, south Qinghai-Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This work makes the quantitative constrain on tectonizations of the Gangdese block, south Qinghai-Tibetan Plateau. Apatite fission track (AFT) dating analyses of 15 samples collected across the Gangdese block show that the Gangdese block went through two periods of tectonizations, during ~37.2 - 18.5 Ma and 18.5 - 8.0 Ma in the south Gangdese block, and during ~47.6 - 5.3 Ma and 5.3 - 0 Ma in the middle Gangdese block. Different upliftings did not take place in the first period and rapid uplifting occurred in the late period. Meantime, there are some differences between the south and middle Gangdese block. Their uplifting rate is 180 m/Ma and 70 m/Ma respectively. The rapid uplifting time in the middle Gangdese block lagged behind the time in the south Gangdese block. It is Chala-Jiacuo-Riduo fault zone that is similar to the Yarlung Zangbo fault zone in control of the tectonization.

  12. Exhumation history of the southern Altiplano plateau (southern Bolivia) constrained by apatite fission track thermochronology

    Science.gov (United States)

    Ege, H.; Sobel, E. R.; Scheuber, E.; Jacobshagen, V.

    2007-02-01

    Although the structural geometry of the Cenozoic Altiplano-Puna plateau in the central Andes is well defined, the temporal evolution of this contractile deformation is poorly constrained. To address this shortcoming, we used apatite fission track thermochronology (AFT) to quantify the cooling and exhumation history along a transect at 21°S in southern Bolivia, through the deformed intermontane Altiplano basin, the doubly vergent thrust belt of the Eastern Cordillera and the inner foreland thrust belt east of the plateau (Interandean Zone). Thermal history modeling combined with published balanced cross sections and stratigraphic data constrain exhumation histories. Exhumation started during the late Eocene (40-36 Ma) in the central Eastern Cordillera, possibly due to bivergent thrusting and Cretaceous rift structure inversion. During the early Oligocene (33-27 Ma), exhumation spread across the study area as the current boundary thrusts of the Eastern Cordillera were activated. The inner west vergent thrust system became active in irregular order until circa 20 Ma, whereas the east vergent Interandean thrust belt formed by eastward propagating deformation since circa 30 Ma. Plateau exhumation continued at ˜0.2 mm/yr until shortening terminated by 11-7 Ma. Shortening within the plateau since circa 30 Ma did not evolve by lateral accretion of thrust wedges; the propagating deformation style is spatially confined to the foreland thrust belt, which initiated coeval to plateau deformation (Interandean Zone) but propagated mainly after circa 10 Ma (Subandean Zone). Early Oligocene plateau-wide tectonically driven exhumation suggests that subduction-related processes had already thermally weakened the continental lithosphere prior to the 27-25 Ma onset of volcanic activity.

  13. Relation between denudation history and sediment supply from apatite fission track thermochronology in the northeast Brazilian Margin

    Science.gov (United States)

    Jelinek, Andrea; Chemale, Farid; Bueno, Gilmar

    2014-05-01

    The aim of this study is to provide a quantitative overview of Mesozoic-Cenozoic morphotectonic evolution and sediment supply to the northeast Brazilian margin. Landscape evolution and denudation histories for the northeastern Brazilian continental margin (Sergipe, Alagoas, Bahia, and Espírito Santo states) were detailed by apatite fission track thermochronology and thermal-history modeling and related with the sedimentological record of the offshore basins of the passive margin for a comparison with their denudational history. Approximately one hundred basement samples were analyzed from the coast to the inland of the Brazilian margin. The apparent fission track ages vary from 360 to 61 Ma and confined fission track lengths vary between 10 and 14.6 µm, indicating that not all of the samples recorded the same cooling events. The results of apatite fission track ages indicate that the area has been eroded regionally since the Mesozoic (Conquista and Borborema Plateaus, and Mantiqueira Range record a Cretaceous-Paleogene onset of exhumation. This timing is consistent with the offshore sedimentary record, wherein a large clastic wedge started forming in the northeastern Sergipe-Alagoas basin, which suggests Sergipe-Alagoas basin records drainage reorganization and extension of the São Francisco River catchment. Interestingly, the Camamu basin, adjacent to the section of the margin does not record syn/post-rift exhumation, does contain a 6-km thick sedimentary succession, which should thus have been derived from more distal sources. The Neogene final denudation is observed throughout the study area and show conspicuous recent exhumation. The post-rift (<40 Ma) offshore sedimentation rates are generally lower than during preceding phases. This final sedimentary succession is thinner in all basins, consistent with limited onshore erosion during this time.

  14. Evidence of post-Gondwana breakup in Southern Brazilian Shield: Insights from apatite and zircon fission track thermochronology

    Science.gov (United States)

    Oliveira, Christie Helouise Engelmann de; Jelinek, Andréa Ritter; Chemale, Farid; Bernet, Matthias

    2016-01-01

    Apatite and zircon fission track thermochronology studies are applied to basement and sedimentary rocks from the Sul-Rio-Grandense Shield to unravel the tectonic history of the onshore southernmost Brazilian margin. The Sul-Rio-Grandense Shield is a major geotectonic feature of southernmost Brazil that includes Paleoproterozoic basement areas and Neoproterozoic fold belts linked to the Brasiliano/Pan-African orogeny. Crustal reworking and juvenile accretion events related to this cycle were dated in the region between 900 and 500 Ma and were responsible for the assembly of southwestern Gondwana in southeastern South America. Apatite fission track (AFT) ages range from 340 ± 33 to 77 ± 6 Ma and zircon fission track (ZFT) ages range from ca. 386 to 210 Ma. Based on thermal history modeling, the most part of the samples record an early cooling event during the Carboniferous, which reflect the main tectonic activity of the final stages of the Gondwanides at the Pacific margin of West Gondwana. Subsequently, the Permo-Triassic cooling event is related to the last stages of the Gondwanides, with convergence along the southern border of Western Gondwana and consequent reactivation of N-S and NE-SW trending basement structures. The onset of initial breakup of southwestern Gondwana with opening of the South Atlantic Ocean is mostly recorded in the eastern terrain and ZFT ages show that the temperature during this period was high enough for total or at least partial resetting of fission tracks in zircon. The last cooling event of the Sul-Rio-Grandense Shield records the final breakup between South America and Africa, which began during the Late Cretaceous. However, the Cenozoic rapid cooling episode probably is a result of plate adjustment after breakup and neotectonic reactivation of faults associated with South Atlantic rift evolution.

  15. Multiple cooling episodes in the Central Tarim (Northwest China) revealed by apatite fission track analysis and vitrinite reflectance data

    Science.gov (United States)

    Chang, Jian; Qiu, Nansheng; Song, Xinying; Li, Huili

    2016-06-01

    Apatite fission track and vitrinite reflectance are integrated for the first time to study the cooling history in the Central Tarim, northwest China. The paleo-temperature profiles from vitrinite reflectance data of the Z1 and Z11 wells showed a linear relationship with depth, suggesting an approximately 24.8 °C/km paleo-geothermal gradient and 2700-3900 m of erosion during the Early Mesozoic. The measured apatite fission track ages from well Z2 in the Central Tarim range from 39 to 159 Ma and effectively record the Meso-Cenozoic cooling events that occurred in Central Tarim. Moreover, two cooling events at 190-140 Ma in the Early Jurassic-Early Cretaceous and 80-45 Ma in the Late Cretaceous-Paleocene revealed by measured AFT data and thermal modeling results are related to the collisions of the Qiangtang-Lhasa terranes and the Greater India Plate with the southern margin of the Eurasian Plate, respectively. This study provides new insights into the tectonic evolution of the Tarim Basin (and more broadly Central Asia) and for hydrocarbon generation and exploration in the Central Tarim.

  16. Zircon and apatite fission track analyses on mineralization ages and tectonic activities of Tuwu-Yandong porphyry copper deposit in northern Xinjiang, China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The mineralization ages reported in the past in the Tuwu-Yandong copper district not only are different, but also fall into the Hercynian epoch. This study has achieved 9 zircon and 7 apatite fission track analysis results. The zircon fission track ages range from 158 Ma to 289 Ma and the apatite ages are between 64 Ma and 140 Ma. The mineralization accords with the regional tectonics in the copper district. We consider that the zircon fission track age could reveal the mineralization age based on annealing zone temperature of 140-300℃ and retention temperature of ~250℃ for zircon fission track, and metallogenetic temperature of 120-350℃ in this ore district. Total three mineralization epochs have been identified, i.e., 289-276 Ma,232-200 Ma and 165-158 Ma, and indicate occurrence of the mineralization in the Indosinian and Yanshan epochs. Corresponding to apatite fission track ages, the three tectonic-mineralizing epochs are 140-132 Ma, 109-97 Ma and 64 Ma, which means age at about 100℃ after the mineralization. The three epochs lasted 146 Ma, 108 Ma and about 100 Ma from ~250℃ to ~100℃ and trend decrease from early to late. It is shown by the fission track modeling that this district underwent three stages of geological thermal histories, stable in Cretaceous and cooling both before Cretaceous and after 20 Ma.

  17. The thermal history of the Miocene Ibar Basin (Southern Serbia: new constraints from apatite and zircon fission track and vitrinite reflectance data

    Directory of Open Access Journals (Sweden)

    Andrić Nevena

    2015-02-01

    Full Text Available The Ibar Basin was formed during Miocene large scale extension in the NE Dinaride segment of the Alpine- Carpathian-Dinaride system. The Miocene extension led to exhumation of deep seated core-complexes (e.g. Studenica and Kopaonik core-complex as well as to the formation of extensional basins in the hanging wall (Ibar Basin. Sediments of the Ibar Basin were studied by apatite and zircon fission track and vitrinite reflectance in order to define thermal events during basin evolution. Vitrinite reflectance (VR data (0.63-0.90 %Rr indicate a bituminous stage for the organic matter that experienced maximal temperatures of around 120-130 °C. Zircon fission track (ZFT ages indicate provenance ages. The apatite fission track (AFT single grain ages (45-6.7 Ma and bimodal track lengths distribution indicate partial annealing of the detrital apatites. Both vitrinite reflectance and apatite fission track data of the studied sediments imply post-depositional thermal overprint in the Ibar Basin. Thermal history models of the detritial apatites reveal a heating episode prior to cooling that began at around 10 Ma. The heating episode started around 17 Ma and lasted 10-8 Ma reaching the maximum temperatures between 100-130 °C. We correlate this event with the domal uplift of the Studenica and Kopaonik cores where heat was transferred from the rising warm footwall to the adjacent colder hanging wall. The cooling episode is related to basin inversion and erosion. The apatite fission track data indicate local thermal perturbations, detected in the SE part of the Ibar basin (Piskanja deposit with the time frame ~7.1 Ma, which may correspond to the youngest volcanic phase in the region.

  18. Mesozoic and Cenozoic uplift and exhumation of the Bogda Mountain, NW China:Evidence from apatite fission track analysis

    Institute of Scientific and Technical Information of China (English)

    Wenhao Tang; Zhicheng Zhang; Jianfeng Li; Ke Li; Zhiwen Luo; Yan Chen

    2015-01-01

    Apatite fission track (AFT) analysis on samples collected from a Paleozoic series is used to constrain the cooling history of the Bogda Mountain, northwest China. AFT ages range from 136.2 to 85.6 Ma and are younger than rock depositional ages and the mean confined track lengths (11.0e13.2 mm) mostly showing unimodal distribution are shorten, indicating significant track-annealing. Thermal histories modeling based on the distribution of fission-track lengths combined with the regional geological data show that two rapid cooling phases occurred in the latest Jurassiceearly Cretaceous and the OligoceneeMiocene. Those new data together with previous published data show that the AFT ages become younger from the southwest to northeast in the western Bogda Mountain and its adjacent areas. The fission-track ages of the southwest area are relatively older (>100 Ma), recording the earlier rapid uplift phase during the late JurassiceCretaceous, while the ages in the north pied-mont of the Bogda Mountain (namely the northeast part) are younger (<60 Ma), mainly reflecting the later rapid uplift phase in the OligoceneeMiocene. The trend of younger AFT ages towards the northeast might be explained by post-Cretaceous large-scale crustal tilting towards the southwest. In the thrust fault-dominated northern limbs of the Bogda Mountain, AFT ages reveal a discontinuous pattern with age-jumps across the major fault zones, showing a possible strata tilting across each thrust faults due to the thrust ramps during the Cenozoic. The two rapid uplift stages might be related to the accretion and collision in the southern margin of the Asian continent during the late Jurassic and late Cenozoic, respectively.

  19. Mesozoic and Cenozoic uplift and exhumation of the Bogda Mountain, NW China: Evidence from apatite fission track analysis

    Directory of Open Access Journals (Sweden)

    Wenhao Tang

    2015-07-01

    Full Text Available Apatite fission track (AFT analysis on samples collected from a Paleozoic series is used to constrain the cooling history of the Bogda Mountain, northwest China. AFT ages range from 136.2 to 85.6 Ma and are younger than rock depositional ages and the mean confined track lengths (11.0–13.2 μm mostly showing unimodal distribution are shorten, indicating significant track-annealing. Thermal histories modeling based on the distribution of fission-track lengths combined with the regional geological data show that two rapid cooling phases occurred in the latest Jurassic–early Cretaceous and the Oligocene–Miocene. Those new data together with previous published data show that the AFT ages become younger from the southwest to northeast in the western Bogda Mountain and its adjacent areas. The fission-track ages of the southwest area are relatively older (>100 Ma, recording the earlier rapid uplift phase during the late Jurassic–Cretaceous, while the ages in the north piedmont of the Bogda Mountain (namely the northeast part are younger (<60 Ma, mainly reflecting the later rapid uplift phase in the Oligocene–Miocene. The trend of younger AFT ages towards the northeast might be explained by post-Cretaceous large-scale crustal tilting towards the southwest. In the thrust fault-dominated northern limbs of the Bogda Mountain, AFT ages reveal a discontinuous pattern with age-jumps across the major fault zones, showing a possible strata tilting across each thrust faults due to the thrust ramps during the Cenozoic. The two rapid uplift stages might be related to the accretion and collision in the southern margin of the Asian continent during the late Jurassic and late Cenozoic, respectively.

  20. Thermal History of Rocks in the Shiwandashan Basin, Southern China: Evidence from Apatite Fission-Track Analysis

    Institute of Scientific and Technical Information of China (English)

    Wang Xinwei; Wang Xinwen; Ma Yongsheng

    2005-01-01

    Based on interpretations of the apatite fission-track analysis data for 10 outcrop samples and forward modeling of confined fission-track length distributions, the thermal history of rocks in the Shiwandashan basin and its adjacent area, southern China, has been qualitatively and semi-quantitatively studied. The results reflect several features of the thermal history. Firstly, all the samples have experienced temperatures higher than 60-70 ℃. Secondly, the time that the basement strata (T1b) on the northwestern side of the Shiwandashan basin were uplifted and exhumed to the unannealed upper crust (with a paleogeotemperature of below 60-70 ℃) is much earlier than the basement rocks (γ15) on the southeastern side of the basin. Thirdly, the thermal history of samples from the basin can be divided into six stages, I.e., the fast burial and heating stage (220-145 Ma), the transient cooling stage (145-135 Ma), the burial and heating stage (135-70 Ma), the rapid cooling stage (70-50 Ma), the relatively stable stage (50-20 Ma) and another rapid cooling stage (20 Ma to present).

  1. Apatite fission track thermochronology of Khibina Massif (Kola Peninsula, Russia): Implications for post-Devonian Tectonics of the NE Fennoscandia

    Science.gov (United States)

    Veselovskiy, Roman V.; Thomson, Stuart N.; Arzamastsev, Andrey A.; Zakharov, Vladimir S.

    2015-12-01

    The thermal history of the Kola Peninsula area of NE Fennoscandia remains almost fully unknown because of the absence of any thermochronological data such as apatite and/or zircon fission track or (Usbnd Th)/He ages. In order to fill this gap and to constrain the post-Devonian erosion and exhumation history of this region, we present the results of apatite fission track (AFT) dating of eleven samples selected from the cores taken from different depths of the northern part of the Khibina intrusive massif. The Rbsbnd Sr isochron age of this alkaline magmatic complex which is located at the center of Kola Peninsula is 368 + 6 Ma (Kramm and Kogarko, 1994). Samples were analyzed from depths between + 520 and - 950 m and yielded AFT ages between 290 and 268 Ma with an age uncertainty (1σ) of between ± 19 Ma (7%) and ± 42 Ma (15%). Mean track lengths (MTL) lie between 12.5 and 14.4 μm. Inverse time-temperature modeling was conducted on the age and track length data from seven samples of the Khibina massif. Thermal histories that best predict the measured data from three samples with the most reliable data show three stages: (1) 290-250 Ma-rapid cooling from > 110 °C to 70 °C/50 °C for lower/upper sample correspondingly; (2) 250-50 Ma-a stable temperature stage; (3) 50-0 Ma-slightly increased cooling rates down to modern temperatures. We propose that the first cooling stage is related to late-Hercynian orogenesis; the second cooling stage may be associated with tectonics accompanying with opening of Arctic oceanic basin. The obtained data show that geothermal gradient at the center of Kola Peninsula has remained close to the modern value of 20 °C/km for at least the last 250 Myr. AFT data show that the Khibina massif has been exhumed not more then 5-6 km in the last 290 Myr.

  2. Late Mesozoic Thermotectonic Evolution of the Jueluotage Range,Eastern Xinjiang, Northwest China: Evidence from Apatite Fission Track Data

    Institute of Scientific and Technical Information of China (English)

    ZHU Wenbin; WAN Jinglin; SHU Liangshu; ZHANG Zhiyong; SU Jinbao; SUN Yan; GUO Jichun; ZHANG Xueyun

    2008-01-01

    Although many authors have emphasized the Cenozoic history of deformation, exhumation and cooling in the Tiaushan area related to the India-Asia collision, very little is known about the Mesozoic history of compression and uplift within the Tianshan. In order to obtain information about the Mesozoic exhumation history and processes of cooling in eastern Tianshan, fission track methods on apatite were used. Sampling was made in the Jueluotage Range. Three samples (Z001-Z003) were taken from granite in borehole ZK6301 of Yandong pluton; the ages range from 97.0 to 87.6 Ma that are much younger than the pluton age which was dated by U-Pb zircon at 334±2 Ma. Two samples in northern piedmont of the Jueluotage Range were collected from Jurassic strata in Dikaner (DK001) and Dananhu (D001) whose ages are 91.5 and 93.4 Ma respectively. The average apparent exhumation rate is 0.039 mm/a calculated by extrapolation on the basis of Yandong samples, indicating an extremely slow exhumation in the Jueluotage Range since the Late Cretaceous. Two Jurassic samples reached the maximum depths after deposition and experienced the maximum temperatures of ca. 105 and 108℃ until the late Early Cretaceous before a period of cooling and exhumation occurred at 114 and 106 Ma.

  3. Apatite fission track thermochronology in the Kuluketage and Aksu areas, NW China: Implication for tectonic evolution of the northern Tarim

    Directory of Open Access Journals (Sweden)

    Zhiyong Zhang

    2016-03-01

    Full Text Available Tarim Precambrian bedrocks are well exposed in the Kuluketage and Aksu areas, where twenty four samples were taken to reveal the denudation history of the northern Tarim Craton. Apatite fission track dating and thermal history modeling suggest that the northern Tarim experienced multi-stage cooling events which were assumed to be associated with the distant effects of the Cimmerian orogeny and India-Eurasia collision in the past. But the first episode of exhumation in the northern Tarim, occurring in the mid-Permian to Triassic, is here suggested to be induced by docking of the Tarim Craton and final amalgamation of the Central Asian Orogenic Belt. The cooling event at ca. 170 Ma may be triggered by the Qiangtang-Eurasia collision. Widespread Cretaceous exhumation could be linked with docking of the Lhasa terrane in the late Jurassic. Cenozoic reheating and recooling likely occurred because of the north-propagating stress, however, this has not affected the northern Tarim much because the Tarim is characterized by rigid block-like motion.

  4. Links between tectonism and exhumation in the Spanish Pyrenees: Evidence from apatite fission track analysis and Ar fault dating

    Science.gov (United States)

    Rahl, J. M.; Haines, S. H.; van der Pluijm, B. A.

    2009-12-01

    Analytical, numerical, and mechanical models of orogenic wedges suggest that the structural and erosional evolution of mountain belts are tightly linked. For example, erosion in the core of a mountain belt may thin a wedge and drive out-of-sequence faulting to reestablish critical taper. To provide a field-based test of these ideas, we present new geochronologic constraints on the deformational and erosional history of the orogenic wedge exposed in the south-central Spanish Pyrenees. Apatite fission-track data from the syn-orogenic sediments of the Sierra de Sis conglomerate reveal generally invariant ages in strata deposited between about 42 and 27 Ma. These data, as well as track-length distributions indicative of rapid cooling, imply the bedrock in the core of the wedge that produced the sediment experienced fast exhumation that began by at least 48 Ma and continued until 42 Ma. Numerical modeling of the detrital data suggests the source region experienced a deceleration in erosion rate from about 1.0 mm/yr to less than 0.5 to 0.2 mm/yr. Published bedrock thermochronometric data collected from the interior of the belt indicate a renewed period of rapid erosional exhumation culminating around 32 Ma. The temporal changes in erosion recorded by thermochronology are correlated with the deformational history of the Pyrenean fold-thrust belt. We present new constraints on fault activity in the Pyrenean foreland through the direct dating of fault gouge by illite age analysis. New fault dates show that tectonic activity youngs towards the interior of the mountain belt, with fault slip correlating to periods of rapid erosion. The relatively outboard Boixols fault has an age of 71 ± 6.4 Ma, reflecting Cretaceous convergence that marks the onset of Pyrenean deformation. Slip on the more inboard Nogueres fault occurred later, at 56 ± 1.4 Ma, consistent with a period of rapid erosion that continued through about 45 Ma inferred from detrital fission-track data. After a long

  5. Late stage thermal history of the Songliao Basin and its tectonic implications: Evidence from apatite fission track (AFT) analyses

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Apatite Fission Track (AFT) data from the Songliao Basin indicates that the late stage tectonic movements in the Songliao Basin have zoning in space and episodes in time. The late stage tectonic movements started from the east part of the basin and migrated westward. AFT ages in the east part of the basin are older than those in the west part of the basin, suggesting that the uplift occurred earlier in the east than in the west. The denudation thickness in the east part of the basin is significantly greater than that in the centre and west. The thermal history evolved two episodes of rapid cooling and subsequent slow cooling processes. Age-depth relationship derived from the AFT data indicates a four-episode denudation history. Further Monte Carlo random simulation of the AFT data reveals the four changing points of the thermal evolution at 65 Ma, 43.5 Ma, 28 Ma and 15 Ma, respectively. The uplifting and denudation rates from different episodes of evolution are proportional to the plate convergence rate. Based on the above analyses and the regional geologic background, it is concluded that the late stage thermal events in the Songliao Basin are the far field response to the subduction of the Pacific Plate under the Eurasian Plate. The first episode of the rapid cooling probably started at the end of the Nenjiang Formation, climaxed at the end of the Cretaceous and ceased at the Late Eocene. The subsequent slow cooling lasts another 15 Ma. The first episode of the evolution is the far field response to the major episode of the Yanshan Movement and subsequent series of the tectonic reorganization, especially the directional change of the Pacific Movement and also the subduction of the Indian Plate underneath the Eurasian Plate. While the second episode of the evolution is the far field response to the extension and closure of the Sea of Japan. Extension led to the migration and converging of the mantle heat flow to the Sea of Japan and resulted in the rapid cooling

  6. Phanerozoic polycyclic evolution of the southwestern Angola margin: New insights for apatite fission track and (U-Th)/He methodologies

    Science.gov (United States)

    Venancio da Silva, Bruno; Hackspacher, Peter; Carina Siqueira Ribeiro, Marli; Glasmacher, Ulrich Anton

    2016-04-01

    The low-temperature thermochronology has been an important tool to quantify geological process in passive continental margins. In this context, the Angolan margin shows evidence of a polycyclic post-rift evolution marked by different events of uplift, basin inversion and changes in sedimentation rates to the marginal basins, which have controlled the salt tectonics and the hydrocarbon deposits (1,2,3,4). To understand the post break-up evolution of the southwestern Angola margin, it were collected outcrop samples for apatite fission track (AFT) and (U-Th)/He analysis ranging in elevation from 79 m to 1675 m from the coast toward the interior plateau in a profile between Namibe and Lubango cities. The area lies on the edge of Central and Southern Atlantic segments a few kilometers northward the Walvis ridge and encompasses the Archean and Proterozoic basement rocks of the Congo craton. The AFT ages ranging from 120.6 ± 8.9 Ma to 328.8 ± 28.5 Ma and they show a trend of increasing age toward the Great Escarpment with some exceptions. The partial mean track lengths (MTLs) vary between 11.77 ± 1.82 μm to 12.34 ± 1.13 μm with unimodal track length distributions (TDLs). The partial (U-Th)/He ages ranging from 104.85 ± 3.15 Ma to 146.95 ± 4.41 Ma and show the same trend of increasing ages landward, little younger than the AFT ages, which could be interpreted as a fast exhumation episode in Late Jurassic - Early Cretaceous times. The thermal histories modelling has been constrained with the kinetic parameters Dpar (5) and c-axis angle (6) by the software Hefty (7). Both AFT and (U-Th)/He thermal histories modelling indicate three episodes of denudation/uplift driven cooling: (a) from Late Jurassic to Early Cretaceous, (b) a smallest one in the Late Cretaceous and (c) from Oligocene-Miocene to recent, which are compatible with geophysical data of the offshore Namibe basin that estimate the greater thickness of sediments formed in the first and third episodes

  7. Cenozoic denudation of the Wichita Mountains, Oklahoma, and southern mid-continent: apatite fission-track thermochronology constraints

    Science.gov (United States)

    Winkler, Jennifer E.; Kelley, Shari A.; Bergman, Steven C.

    1999-05-01

    Eight new apatite fission-track (AFT) analyses of igneous rocks constrain the low-temperature thermal history of the Wichita Mountains in southwestern Oklahoma. The apparent AFT ages for Mount Scott, which range from 101±14 to 146±45 Ma, display no systematic variation as a function of elevation. AFT age ranges for the rhyolite at Bally Mountain and Mount Sheridan Gabbro are 136±36 to 160±25 Ma and 209±26 to 222±36 Ma, respectively. The mean track lengths for the Wichita Mountain samples range from 11.8 to 13.4 μm with standard deviations of 1.8-3.4 μm, and the track-length distributions are broad with relatively few tracks longer than 14 μm. The AFT age and length data are best fit by a thermal history involving heating of the basement rocks to temperatures of at least 115°C prior to Late Jurassic time, denudation and associated cooling between Late Jurassic and Albian in response to the opening of the Gulf of Mexico, burial by 0.5-1.5 km of Cretaceous sedimentary rocks, and finally cooling due to denudation starting 55-25 Ma and continuing to the present. The thermal history recorded in the AFT data from the Wichita Mountains is similar to thermal histories derived from AFT thermochronology studies along the Ouachita Trend and in the Anadarko Basin. The new data, when combined with AFT data from the Ouachita Deformation Belt, the Anadarko Basin, the eastern Sangre de Cristo Mountains in New Mexico, and the eastern margins of the Wet Mountain and Front Range in Colorado, reveal an interesting pattern of post-Cretaceous denudation in the mid-continent. The amount of Neogene denudation increases westward from about 1 km to 3 km between southwestern Oklahoma and the eastern Sangre de Cristo Mountains in east-central New Mexico, and the timing of onset of denudation decreases from 55-25 Ma in the east to 35-12 Ma toward the west. Along the Southern Rocky Mountains-High Plains boundary, the amount of denudation decreases northward from about 3 km in the

  8. Phanerozoic burial and exhumation history of southernmost Norway estimated from apatite fission-track analysis data and geological observations

    Science.gov (United States)

    Japsen, Peter; Green, Paul F.; Bonow, Johan M.; Chalmers, James A.; Rasmussen, Erik S.

    2016-04-01

    We present new apatite fission-track analysis (AFTA) data from 27 basement samples from Norway south of ~60°N. The data define three events of cooling and exhumation that overlap in time with events defined from AFTA in southern Sweden (Japsen et al. 2015). The samples cooled below palaeotemperatures of >100°C in a major episode of Triassic cooling as also reported by previous studies (Rohrman et al. 1995). Our study area is just south of the Hardangervidda where Cambrian sediments and Caledonian nappes are present. We thus infer that these palaeotemperatures reflect heating below a cover that accumulated during the Palaeozoic and Triassic. By Late Triassic, this cover had been removed from the Utsira High, off SW Norway, resulting in deep weathering of a granitic landscape (Fredin et al. 2014). Our samples were therefore at or close to the surface at this time. Palaeotemperatures reached ~80°C prior to a second phase of cooling and exhumation in the Jurassic, following a phase of Late Triassic - Jurassic burial. Upper Jurassic sandstones rest on basement near Bergen, NW of our study area (Fossen et al. 1997), and we infer that the Jurassic event led to complete removal of any remaining Phanerozoic cover in the region adjacent to the evolving rift system prior to Late Jurassic subsidence and burial. The data reveal a third phase of cooling in the early Miocene when samples that are now near sea level cooled below palaeotemperatures of ~60°C. For likely values of the palaeogeothermal gradient, such palaeotemperatures correspond to burial below rock columns that reach well above the present-day landscape where elevations rarely exceed 1 km above sea level. This implies that the present-day landscape was shaped by Neogene erosion. This is in agreement with the suggestion of Lidmar-Bergström et al. (2013) that the near-horizontal Palaeic surfaces of southern Norway are the result of Cenozoic erosion to sea level followed by uplift to their present elevations in a

  9. Cenozoic burial and exhumation history of the Kangerlussuaq area, East Greenland, revealed by new apatite fission-track data

    Science.gov (United States)

    Japsen, Peter; Green, Paul F.; Bonow, Johan M.; Nielsen, Troels F.

    2010-05-01

    The Kangerlussuaq area in East Greenland (c. 68°N) has witnessed a complex geological development during the Cenozoic. The Skaergaard intrusion and the up to 5 km thick flood basalts formed during a short period around 55 Ma, and subsequently numerous intrusive bodies were emplaced, primarily during the Eocene. Relatively little is known about the geological history over the last 35 Myr, other than that an outlier of Middle Miocene lavas is located in the area at an elevation of c. 2.7 km. At the present-day, the area is deeply eroded and magmatic bodies that were emplaced deeply in the crust, are now exposed at the surface, but at the same time, the area has a significant elevation and even hosts the highest peak in Greenland, Gunbjørn Fjeld, 3.7 km above sea level. To unravel the history of burial and exhumation in the Kangerlussuaq area, new apatite fission-track analysis (AFTA) data has been acquired for 75 rock samples. Preliminary results show that the area has been subject to several phases of cooling since burial under the Palaeogene flood basalts. Phases of regional cooling along the coast that occurred at the Eocene-Oligocene transition and in the late Neogene are interpreted to be due to uplift and exhumation. Cooling events of local extent that occurred in the Eocene, Oligocene and Miocene are interpreted to be related to both exhumation and to circulating hot fluids. Results from samples along vertical transects reveal details of the protracted exhumation history, and that the present topography was formed during the late Neogene.

  10. Mesozoic and Cenozoic Cooling History of the Qiangtang Block, Northern Tibet, China: New Constraints from Apatite and Zircon Fission Track Data

    Directory of Open Access Journals (Sweden)

    Chunyan Song

    2013-01-01

    Full Text Available This study used a new set of zircon and apatite fission track ages to quantitatively document the tectonic evolution and cooling histories of the Qiangtang block of the central Tibetan Plateau. The results indicate that the Qiangtang block underwent three cooling stages at ~148 - 73, ~50 - 20, and ~20 - 0 Ma. The three-stage cooling history and tectonic exhumation were controlled by the closure of the Bangong-Nujiang Suture during the Late Jurassic-Late Cretaceous, the India-Asia collision in the Paleogene, and the underthrusting of the India Plate during the Late Cenozoic. In addition to revealing the Late Jurassic-Late Cretaceous cooling events, the annealing patterns of the zircon fission track samples indicate different burial depths, which may help identify the Jurassic basin characteristics of the Qiangtang block. The apatite fission track (AFT ages range from 60 ¡_ 5 Ma to 26 ¡_ 3 Ma, with a mean age of 44 Ma. These ages indicate that the Cenozoic exhumation of the Qiangtang block may have started in the Eocene. Inverse modeling of the AFT data shows that the Qiangtang block had a relatively slow cooling rate of approximately 0.5 - 1¢XC Myr-1 from 50 to 20 Ma. After ~20 Ma, most of the samples show evidence for a rapid cooling stage with a cooling rate of 4 - 6¢XC Myr-1.

  11. Apatite-fission-track geochronology and its tectonic correlation in the Dabieshan orogen, central China

    Institute of Scientific and Technical Information of China (English)

    XU; Changhai; ZHOU; Zuyi; P.; Van; Den; Haute; R.; A.; Donel

    2005-01-01

    AFT data of granitoid and metamorphic samples from the Dabieshan orogen have an age range between 96.4 Ma and 41.9 Ma coupled with confined track lengths of 11.5-14.0 μm, reflecting the cooling time of rocks differentially through the 100℃±isotherm. The Jurassic-Eogene sediments from the North Huaiyang and Hefei basin, however, yield their AFT ages of 128.8-62.0 Ma with mean track lengths of 8.6-11.9 μm, recording a complicated thermal development of the basin. These AFT data structurally allowing the coupling between the orogen and the basin are to a great extent considered as the result from the control of NNE-trending regional tectonics. It took place approximately at 95-90 Ma that the orogen developed with an abrupt shift from the doming extension to the differential transtension, which is assumed to be related with the changes of the convergence between the Western Pacific and Eurasia plates. The differentially sinistral strike-slipping from the transtension between Tanlu and Shangcheng-Macheng faults brought the doming extension of the orogen shrunk sharply in Late Cretaceous. In Eogene, the full-grown transtension that dominated in East Asia was caused mainly by a rapid decrease of the rates of the Western Pacific convergence, which can be therefore regarded as a major mechanism creating the zonal anomalies of 60-40 Ma in the orogen. The thermal anomaly of 70-40 Ma zonally along the Tanlu fault cooled more slowly than the anomaly of 60-55 Ma zoning along the Shangcheng-Macheng fault, but the 60-40 Ma anomaly trending E-W in hinterlands of the orogen seems to be relicts of the doming extension as a result of intensive rebuilding by the transtension. In addition, the orogen was also reactivated by the far-field effect from India-Asia collision in Eogene, where major NWW-trending faults played an important role in facilitating such far-field tectonic transferring. In Oligocene to Miocene, the Dabieshan orogen remained a few thermal disturbances with their

  12. Spatial variation in exhumation rates across Ladakh and the Karakoram: New apatite fission track data from the Eastern Karakoram, NW India

    Science.gov (United States)

    Wallis, David; Carter, Andrew; Phillips, Richard J.; Parsons, Andrew J.; Searle, Michael P.

    2016-03-01

    Characterization of low-temperature cooling histories and associated exhumation rates is critical for deciphering the recent evolution of orogenic regions. However, these may vary significantly over relatively short distances within orogens. It is pertinent therefore to constrain cooling histories and hence exhumation rates across major tectonic boundaries. We report the first apatite fission track ages from the Karakoram Fault Zone in the Eastern Karakoram range, which forms part of the western margin of the Tibetan Plateau. Ten samples, from elevations of 3477-4875 m, have apatite fission track dates from 3.3 ± 0.3 Ma to 7.4 ± 1.1 Ma. The ages correspond to modeled average erosional exhumation rates of 0.67 + 0.27/-0.18 mm/yr across the Eastern Karakoram. The results are consistent with a trend northward from the Indus suture zone, across the Ladakh terrane and into the Karakoram, in which tectonic uplift associated with crustal thickening increases toward the north, raising elevation and promoting glaciation and generation of extreme relief. As a result, erosion and exhumation rates increase south to north. Present-day precipitation on the other hand varies little within the study area and on a larger scale decreases southwest to northeast across this portion of the orogen. The Eastern Karakoram results highlight the diverse patterns of exhumation driven by regional variations in tectonic response to collision along the western margin of Tibet.

  13. Thermotectonic history of the southeastern Brazilian margin: Evidence from apatite fission track data of the offshore Santos Basin and continental basement

    Science.gov (United States)

    Engelmann de Oliveira, Christie Helouise; Jelinek, Andréa Ritter; Chemale, Farid; Cupertino, José Antônio

    2016-08-01

    The Santos Basin is the largest offshore sedimentary basin in the southeastern Brazilian margin and originated by breakup of West Gondwana in the Early Cretaceous. We carried out a new thermochronological study by apatite fission track analysis from borehole samples of the Santos Basin and its continental basement to constrain the tectonic history of the southeastern Brazilian margin. Apatite fission track central ages of the basement and borehole samples vary from 21.0 ± 1.8 to 157.0 ± 35.0 Ma and from 6.5 ± 1.1 to 208.0 ± 11.0 Ma, respectively. From thermal modeling, the basement samples reached the maximum paleotemperatures during the final breakup of South America and Africa. The onshore basement and offshore basin record an early thermotectonic event during the Late Cretaceous linked to the uplift and denudation of the Serra do Mar and Serra da Mantiqueira. Maturation of the organic matter in the offshore basin is related with the progressive increase of the geothermal gradient due to burial. The thermal modeling indicates that the oil generation window started at 55-25 Ma. The basement samples experienced the final cooling during the Cenozoic, with an estimated amount of denudation linked to the sedimentary influx in the offshore basin. A rapid cooling during the Neogene becomes evident and it is linked to the reactivation along Precambrian shear zones and change of the Paraíba do Sul drainage system.

  14. The post-orogenic evolution of the Northeast Greenland Caledonides constrained from apatite fission track analysis and inverse geodynamic modelling

    DEFF Research Database (Denmark)

    Pedersen, Vivi Kathrine; Nielsen, S.B.; Gallagher, Kerry

    2012-01-01

    or characteristic trends relative to mean track length. Using these new data and inverse geodynamic modelling, we constrain the evolution in the area since the orogenic collapse of the Caledonides. Exhumation histories are inferred using a uniform stretching model, incorporating variable rates of erosion...... or deposition, and thermal histories are found by solving the one-dimensional transient conduction–advection heat equation. These thermal histories are used with the observed fission track data to constrain acceptable strain rate histories and exhumation paths. The results suggest that rifting has been focused...

  15. Long-term landscape evolution of the South Atlantic "passive" continental margin in Eastern Argentina using apatite fission-track thermochronology

    Science.gov (United States)

    Pfister, Sabrina; Kollenz, Sebastian; Glasmacher, Ulrich A.

    2015-04-01

    To understand the evolution of the "passive" continental margin in Argentina low temperature thermochronology is an appropriate method, which might lead to new insights in this area. The Tandilia System, also called Sierras Septentrionales, is located south of the Río de la Plato Craton in eastern Argentina in the state of Buenos Aires. North of the hills the Salado basin is located whereas the Claromecó basin is situated south of the mountain range. In contrary to most basins along the South American "passive" continental margin, the Tandilia-System and the neighbouring basins trend perpendicular to the coast line. The topography is fairly flat with altitudes up to 350 m. The igneous-metamorphic basement is pre-Proterozoic in age and build up of mainly granitic-tonalitic gneisses, migmatites, amphibolites, some ultramafic rocks and granitoid plutons. It is overlain by a series of Neoproterozoic to early Paleozoic sedimentary rocks (Cingolani 2011), like siliciclastic rocks, dolostones, shales and limestones (Demoulin 2005). The aim of the study is to quantify the long-term landscape evolution of the "passive" continental margin in eastern Argentina in terms of thermal, exhumation and tectonic evolution. For that purpose, samples were taken from the basement of the Sierra Septentrionales and analyzed with the apatite fission-track method. Further 2-D thermokinematic modeling was conducted with the computer code HeFTy (Ketcham 2005; Ketcham 2007; Ketcham et al. 2009). Because there are different hypotheses in literature regarding the geological evolution of this area two different models were generated, one after Demoulin et al. (2005) and another after Zalba et al.(2007). All samples were taken from the Neoproterozoic igneous-metamorphic basement. Apatite fission-track ages range from 101.6 (9.4) to 228.9 (22.3) Ma, and, therefore, are younger than their formation age, indicating all samples have been thermally reset. Six samples accomplished enough confined

  16. Cenozoic evolution of tectono-fluid and metallogenic process in Lanping Basin,western Yunnan Province, Southwest China: Constraints from apatite fission track data

    Institute of Scientific and Technical Information of China (English)

    LI Xiaoming; SONG Yougui

    2006-01-01

    Since the Mesozoic, abundant metal and salt deposits have been formed in the Lanping Basin, western Yunnan Province, Southwest China, constituting a well-known hydrothermal ore belt in China. Most of the deposits are meso-epithermal hydrothermal deposits. This paper preliminarily deals with the mineralization ages of hydrothermal deposits in the Lanping Basin by using the apatite fission track method, and integrates the spatial distribution of the deposits and their regional geological backgrounds, to give the preliminary viewpoints as follows: (1) the apatite fission track ages acquired range from 19.9 Ma to 52.8 Ma, much younger than those of their host strata, so they may be considered to be mineralization ages, which represent the late mineralization period; (2) the apatite fission track ages tend to become younger from the west to the middle of the basin, indicating that the latest evolution of tectono-fluid and/or metallogenic processes of the middle basin ended later than that in the west; (3) in the Paleogene, most of the Cu deposits were formed in the western part of the basin; (4) the major metallogenic processes occur between the Paleogene and the Neogene, because the eastern and western edges of the basin were subducted into and collided with its bilateral continental blocks, respectively, and the central fault was strongly activated, which led to the processes of large-scale ore-forming fluids, and their differentiation and transport because of the variation of their physical and chemical properties. Having been squeezed and uplifted, the Lanping Basin became an intermontane basin that contains many kinds of fluid traps resulting in the formation of different types of ore deposits (for example, Pb-Zn, Cu, Ag) of different scales in the middle of the basin. Simultaneously, the fluids with volatile elements such as Hg, Sb and As were transported upwards along the central fault system and diffused into its subordinate fractures, thus leading to the

  17. Evolution of the Chos Malal and Agrio fold and thrust belts, Andes of Neuquén: Insights from structural analysis and apatite fission track dating

    Science.gov (United States)

    Rojas Vera, E. A.; Mescua, J.; Folguera, A.; Becker, T. P.; Sagripanti, L.; Fennell, L.; Orts, D.; Ramos, V. A.

    2015-12-01

    The Chos Malal and Agrio fold and thrust belts are located in the western part of the Neuquén basin, an Andean retroarc basin of central-western Argentina. Both belts show evidence of tectonic inversion at the western part during Late Cretaceous times. The eastern part is dominated by late Miocene deformation which also partially reactivated the western structures. This work focuses on the study of the regional structure and the deformational event that shaped the relief of this part of the Andes. Based on new field work and structural data and previously published works a detailed map of the central part of the Neuquén basin is presented. Three regional structural cross sections were surveyed and balanced using the 2d Move™ software. In order to define a more accurate uplift history, new apatite fission track analyses were carried on selected structures. These data was used for new thermal history modeling of the inner part of the Agrio and Chos Malal fold and thrust belts. The results of the fission track analyses improve the knowledge of how these fold and thrust belts have grown trough time. Two main deformational events are defined in Late Cretaceous to Paleocene and Late Miocene times. Based on this regional structural analysis and the fission track data the precise location of the orogenic front for the Late Cretaceous-Paleocene times is reconstructed and it is proposed a structural evolution of this segment of the Andes. This new exhumation data show how the Late Cretaceous to Paleocene event was a continuous and uninterrupted deformational event.

  18. The thermal history of the Karoo Moatize-Minjova Basin, Tete Province, Mozambique: An integrated vitrinite reflectance and apatite fission track thermochronology study

    Science.gov (United States)

    Fernandes, Paulo; Cogné, Nathan; Chew, David M.; Rodrigues, Bruno; Jorge, Raul C. G. S.; Marques, João; Jamal, Daud; Vasconcelos, Lopo

    2015-12-01

    The Moatize-Minjova Basin is a Karoo-aged rift basin located in the Tete Province of central Mozambique along the present-day Zambezi River valley. In this basin the Permian Moatize and Matinde formations consist of interbedded carbonaceous mudstones and sandstones with coal seams. The thermal history has been determined using rock samples from two coal exploration boreholes (ca. 500 m depth) to constrain the burial and exhumation history of the basin. Organic maturation levels were determined using vitrinite reflectance and spore fluorescence/colour. Ages and rates of tectonic uplift and denudation have been assessed by apatite fission track analysis. The thermal history was modelled by inverse modelling of the fission track and vitrinite reflectance data. The Moatize Formation attained a coal rank of bituminous coals with low to medium volatiles (1.3-1.7%Rr). Organic maturation levels increase in a linear fashion downhole in the two boreholes, indicating that burial was the main process controlling peak temperature maturation. Calculated palaeogeothermal gradients range from 59 °C/km to 40 °C/km. According to the models, peak burial temperatures were attained shortly (3-10 Ma) after deposition. Apatite fission track ages [146 to 84 Ma (Cretaceous)] are younger than the stratigraphic age. Thermal modelling indicates two episodes of cooling and exhumation: a first period of rapid cooling between 240 and 230 Ma (Middle - Upper Triassic boundary) implying 2500-3000 m of denudation; and a second period, also of rapid cooling, from 6 Ma (late Miocene) onwards implying 1000-1500 m of denudation. The first episode is related to the main compressional deformation event within the Cape Fold Belt in South Africa, which transferred stress northwards on pre-existing transtensional fault systems within the Karoo rift basins, causing tectonic inversion and uplift. During the Mesozoic and most of the Cenozoic the basin is characterized by very slow cooling. The second period

  19. Hematite (U-Th)/He and Apatite Fission-track Dating Constrain Paleofluid Circulation in Faults: An Example from Gower Peninsula Fissure Fills, Wales

    Science.gov (United States)

    Ault, A. K.; Frenzel, M.; Reiners, P. W.; Woodcock, N. H.; Thomson, S. N.

    2015-12-01

    Hematite-calcite fissure fills on the Gower Peninsula, Wales, preserve evidence of faulting, mineralization, and multiple fluid flow events. Fissures are associated with dilational strike-slip faults in early Carboniferous limestone and contain locally brecciated hematite, calcite, and red sediment. Hematite is macroscopically botryoidal, but lobes comprise an intricate aggregate of 0.15-0.5 μm-thick plates with high aspect ratios. Prior work suggests mineralization occurred in either late Carboniferous or late Triassic time. We combine hematite (U-Th)/He dating with apatite (U-Th)/He, apatite fission-track (AFT), and zircon (U-Th)/He thermochronology of fill materials to evaluate the timing and thermal effects of fluid circulation in these structures. Hematite He data from four fissures yield reproducible dates of 141.0 ± 5.1 Ma to 119.9 ± 5.0 Ma. Individual zircon He dates from a sandstone infill sample are ~402-260 Ma, reflecting erosion of source material, and imply a maximum late Permian depositional age. The sandstone AFT date of 131.4 ± 20.1 Ma overlaps with the hematite He results and the apatite He date is ~50 Ma. Reconstruction of the regional burial history from independent geologic constraints reveals modern exposures were not buried and reheated to temperatures hot enough to reset the AFT or hematite He systems in the Triassic-Early Cretaceous. Thus, these data do not simply record ambient cooling from erosion. Hot fluids (~100-150 °C) circulating through fissures in the Early Cretaceous reset the AFT system. Hematite either formed in the Triassic and was also reset by fluids or formed from these fluids. Similar hematite He dates from fault-related mineralization in adjacent south Glamorgan and Cumbria, England, imply concomitant regional hot fluid effects. Our data document hydrothermal fluid circulation, coeval with opening of the North Atlantic Ocean, in these higher permeability fissures and fault veins long after they initially formed

  20. Post-Triassic thermal history of the Tazhong Uplift Zone in the Tarim Basin, Northwest China: Evidence from apatite fission-track thermochronology

    Directory of Open Access Journals (Sweden)

    Caifu Xiang

    2013-11-01

    Full Text Available The Tarim Basin is a representative example of the basins developed in the northwest China that are characterized by multiple stages of heating and cooling. In order to better understand its complex thermal history, apatite fission track (AFT thermochronology was applied to borehole samples from the Tazhong Uplift Zone (TUZ. Twelve sedimentary samples of Silurian to Triassic depositional ages were analyzed from depths coinciding with the apatite partial annealing zone (∼60–120 °C. The AFT ages, ranging from 132 ± 7 Ma (from a Triassic sample to 25 ± 2 Ma (from a Carboniferous sample, are clearly younger than their depositional ages and demonstrate a total resetting of the AFT thermometer after deposition. The AFT ages vary among different tectonic belts and decrease from the No. Ten Faulted Zone (133–105 Ma in the northwest, the Central Horst Zone in the middle (108–37 Ma, to the East Buried Hill Zone in the south (51–25 Ma. Given the low magnitude of post-Triassic burial heating evidenced by low vitrinite reflectance values (Ro < 0.7%, the total resetting of the AFT system is speculated to result from the hot fluid flow along the faults. Thermal effects along the faults are well documented by younger AFT ages and unimodal single grain age distributions in the vicinity of the faults. Permian–early Triassic basaltic volcanism may be responsible for the early Triassic total annealing of those samples lacking connectivity with the fault. The above arguments are supported by thermal modeling results.

  1. Composition dependent thermal annealing behaviour of ion tracks in apatite

    Energy Technology Data Exchange (ETDEWEB)

    Nadzri, A., E-mail: allina.nadzri@anu.edu.au [Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, ACT 2601 (Australia); Schauries, D.; Mota-Santiago, P.; Muradoglu, S. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, ACT 2601 (Australia); Trautmann, C. [GSI Helmholtz Centre for Heavy Ion Research, Planckstrasse 1, 64291 Darmstadt (Germany); Technische Universität Darmstadt, 64287 Darmstadt (Germany); Gleadow, A.J.W. [School of Earth Science, University of Melbourne, Melbourne, VIC 3010 (Australia); Hawley, A. [Australian Synchrotron, 800 Blackburn Road, Clayton, VIC 3168 (Australia); Kluth, P. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, ACT 2601 (Australia)

    2016-07-15

    Natural apatite samples with different F/Cl content from a variety of geological locations (Durango, Mexico; Mud Tank, Australia; and Snarum, Norway) were irradiated with swift heavy ions to simulate fission tracks. The annealing kinetics of the resulting ion tracks was investigated using synchrotron-based small-angle X-ray scattering (SAXS) combined with ex situ annealing. The activation energies for track recrystallization were extracted and consistent with previous studies using track-etching, tracks in the chlorine-rich Snarum apatite are more resistant to annealing than in the other compositions.

  2. Comment on: ``Experimental evidence for the pressure dependence of fission track annealing in apatite'' by A.S. Wendt et al. [Earth Planet. Sci. Lett. 201 (2002) 593-607

    Science.gov (United States)

    Kohn, B. P.; Belton, D. X.; Brown, R. W.; Gleadow, A. J. W.; Green, P. F.; Lovering, J. F.

    2003-10-01

    The pressure experiments reported by Wendt et al. are cast in such a way as to question the fundamental basis underpinning apatite fission track thermochronology, implying the possibility of a large systematic error in previous interpretations. We find however, that the study is severely compromised by fundamental errors in both experimental design and execution, as well as lacking in consideration of a substantial body of previous work in the area of fission track annealing studies. Wendt et al. have not attempted to extrapolate the results of their experiments to geologically relevant heating times and temperatures. This has been the fundamental test that all previous annealing models have had to pass. Their study clearly fails this test. Moreover, if significant pressure dependence does exist then it is implicit in existing, deep borehole-consistent annealing models. Whilst such models are interpolated in terms of temperature, the borehole test means that they also accommodate any other factors, which correlate with temperature, including pressure. The implications of the results reported by Wendt et al. have been overstated. Far from being "intimidating", we find that they have little relevance either to previous studies of apatite fission track annealing and extrapolations based on them, or to the routine application of fission track analysis to elucidate thermal history information under geological conditions.

  3. The geomorphic development of the escarpment of the Eritrean rift flank (southern Red Sea): combined use of apatite fission-track and (U-Th)/He thermochronometry

    Science.gov (United States)

    Balestrieri, M. L.; Stuart, F. M.

    2003-04-01

    The Eritrean continental margin along the southern Red Sea has a morphology typical of high-elevation rifted margins. A steeply rising escarpment separates a low relief coastal plain from a high plateau that reaches altitudes of more than 2,500 m. Escarpments at high-elevation rifted margins are salient morphological features, and how they evolve through time gives clues on the respective roles of tectonics and erosion in the formation of passive margins. Apatite fission-track (AFT) analysis was applied along four transects stretching from the high plateau to the coastal lowlands. AFT ages increase from 10-16 Ma at the coast to 300-400 Ma on the plateau. The ages from the coast imply continental break-up occurred at 10-16 Ma and coincided with rapid erosion of more than 3.5-4 km. This is incompatible with formation of the escarpment by erosion of a downwarped rifted margin and points to escarpment retreat or downwearing of an elevated rift shoulder. Apatite (U-Th)/He thermochronology provides a more sensitive tool to evaluate the amount and speed of post-break-up erosion. (U-Th)/He analysis has been applied to apatites from the Asmara Massawa road transect (A-M) and the Dandero River course (D) from the southeastern border of the Eritrean plateau to the border of the Danakil depression. Along both transects He ages are consistently younger than AFT ages. In the A-M transect He ages increase systematically from 8 to 55 Ma across the coastal plain and the lowest part of the escarpment, up to 170 Ma on the plateau. In the D transect, along the plain and the lowest part of the escarpment, He ages span a narrow range (9 to 13 Ma) and do not correlate with elevation or distance from the border of the Danakil depression. A sample from the high plateau has an apparently young He age (48 Ma) which requires 1 km of post-break-up erosion of the plateau in this region. In both transects samples with AFT age <32 Ma yield He ages of 8-10 Ma, providing a strong constraint on the

  4. Cenozoic Exhumation and Thrusting in the Northern Qilian Shan,Northeastern Margin of the Tibetan Plateau:Constraints from Sedimentological and Apatite Fission-Track Data

    Institute of Scientific and Technical Information of China (English)

    GUO Zhaojie; LU Jiemin; ZHANG Zhicheng

    2009-01-01

    The Qilian Shan lies along the northeastern edge of the Tibetan Plateau.To constrain its deformation history,we conducted integrated research on Mesozoic-Cenozoic stratigraphic sections in the Jiuxi Basin immediately north of the mountain range.Paleocurrent measurements,sandstone compositional data,and facies analysis of Cenozoic stratigraphic sections suggest that the Jiuxi Basin received sediments from the Altyn Tagh Range in the northwest,initially in the Oligocene(~33 Ma),depositing the Huoshaogou Formation in the northern part of the basin.Later,the source area of the Jiuxi Basin changed to the Qilian Shan in the south during Late Oligocene(~27 Ma),which led to the deposition of the Baiyanghe Formation.We suggest that uplift of the northern Qilian Shan induced by thrusting began no later than the Late Oligocene.Fission-track analysis of apatite from the Qilian Shan yields further jnformation about the deformation history of the northern Qilain Shan and the Jiuxi Basin.It shows that a period of rapid cooling,interpreted as exhumation,initiated in the Oligocene.We suggest that this exhumation marked the initial uplift of the Qilian Shan resulting from the India-Asia collision.

  5. Using apatite fission track thermochronology to document the deformation sequence in an exhumed foreland basin: an example from the southern Pyrenees.

    Science.gov (United States)

    Meresse, F.; Labaume, P.; Jolivet, M.; Teixell, A.

    2009-04-01

    Université Montpellier 2, INSU-CNRS, Laboratoire Géosciences Montpellier, cc060, 34095 Montpellier Cedex 5, France florian.meresse@gm.univ-montp2.fr The study of foreland basins provides important constraints on the evolution of orogenic wedges. In particular, the study of tectonics-sedimentation relationships is essential to date the tectonic activity. However, processes linked to wedge growth are not always completely recorded by the tecto-sedimentary markers, and thermochronological study of the basin-fill can provide further insights. In this work, we have combined apatite fission track analysis (apatite FTA) with structural analysis to precise the timing of the deformation sequence and to characterise the coupling between thrust activity, burial and denudation in the south-Pyrenean foreland basin, a proximal foredeep of the Pyrenees that has been incorporated in the Pyrenean thrust wedge. We have focused the study on a NNE-SSW cross-section of the south-vergent thrust system from the southern flank of the Axial Zone to the South-Pyrenean Frontal Thrust (SPFT), in the west-central part of the belt. This section provides a complete transverse of the South-Pyrenean Zone, here corresponding to the Ainsa and Jaca basins. Apatite FTA provides important new constraints on the south-Pyrenean foreland basin evolution: (i) Data show the southward decrease of the fission track reset level, from a total reset (indicating heating at Tmax>110°C) in the Paleozoic of the Axial Zone, to a partial reset (110°C>Tmax>60°C) in the lower-middle Eocene Hecho Group turbidites in the northern part of the Jaca basin, and to the absence of reset (TmaxJaca basin. This indicates a decreasing amount of denudation going southwards, from more than 4.5 km in the north to less than 2.5 km in the south if we assume an average geothermal gradient around 25°/km. The structural setting of the Jaca basin attests that the burial of sediments was mainly due to sedimentary accumulation. (ii

  6. Mesozoic exhumation history and palaeolandscape of the Iberian Massif in eastern Galicia from apatite fission-track and (U+Th)/He data

    Science.gov (United States)

    Grobe, R. W.; Alvarez-Marrón, J.; Glasmacher, U. A.; Stuart, F. M.

    2014-03-01

    Apatite fission-track (AFT) and (U+Th)/He (AHe) data, combined with time-temperature inverse modelling, reveal the cooling and exhumation history of the Iberian Massif in eastern Galicia since the Mesozoic. The continuous cooling at various rates correlates with variation of tectonic boundary conditions in the adjacent continental margins. The data provide constraints on the 107 timescale longevity of a relict paleolandscape. AFT ages range from 68 to 174 Ma with mean track lengths of 10.7 ± 2.6 to 12.6 ± 1.8 μm, and AHe ages range from 73 to 147 Ma. Fastest exhumation (≈0.25 km/Ma) occurred during the Late Jurassic to Early Cretaceous main episode of rifting in the adjacent western and northern margins. Exhumation rates have decreased since then and have been approximately one order of magnitude lower. Across inland Galicia, the AFT data are consistent with Early Cretaceous movement on post-Variscan NE trending faults. This is coeval with an extensional episode offshore. The AHe data in this region indicate less than 1.7 km of denudation in the last 100 Ma. This low exhumation suggests the attainment of a mature landscape during Late Cretaceous post-rift tectonic stability, whose remains are still preserved. The low and steady rate of denudation prevailed across inland Galicia despite minor N-S shortening in the northern margin since ≈45 Ma ago. In north Galicia, rock uplift in response to NW strike-slip faulting since Early Oligocene to Early Miocene has caused insufficient exhumation (<3 km) to remove the Mesozoic cooling signal recorded by the AFT data.

  7. Effects of Fission-track Angle to Crystallographic C Axis in Apatite on Thermal History%磷灰石裂变径迹与结晶C轴的夹角对模拟热历史的影响

    Institute of Scientific and Technical Information of China (English)

    焦亚先; 邱楠生; 阙永泉

    2013-01-01

    磷灰石裂变径迹退火行为是磷灰石裂变径迹技术模拟热历史的基础,退火程度的不同会导致径迹的长度不同,其中退火的各向异性(与结晶C轴夹角不同退火行为不同)是导致长度差异的重要因素。首先利用C轴投影模型将任意夹角的径迹转化成与C轴平行的径迹,以此消除分布方位的影响,进而探讨实际测量长度相同而分布方位不同的径迹模拟的热历史之间的差异。研究结果表明,磷灰石裂变径迹与结晶 C轴夹角不同揭示的最高古地温之间最大差异为15℃,用来研究剥蚀量和年轻造山带冷却抬升速率引起的最大差异可分别达到430 m及1.5℃/Ma,揭示构造抬升事件的初始抬升时间最大可相差2Ma。因此,在实际模拟热历史时应注意该参数的影响,准确测量磷灰石裂变径迹与结晶C轴的夹角将有助于提高模拟热历史的精度。%Thermal histories modeled from apatite fission-track(FT)data are dependent upon the annealing beha-vior of apatite fission-tracks.It has been confirmed that the rate of fission-track annealing correlates with apatite structure and the annealing rate is faster for fission-tracks with higher angle to crystallographic C axis,so different rates of fission-track annealing will eventually lead to different length distributions.In this study,the apatite fis-sion-track length C axis projection model was used to eliminate the effects of different angles to crystallographic C axis,and then the difference of thermal histories modeled from apatite fission-tracks with the same length and dif-ferent angle to crystallographic C axis was discussed.This paper has showed that the largest difference of the maxi-mum palaeo-geotemperatures among the modeling history is 15 ℃,and the largest difference in the erosion amount,cooling uplift rate and initial uplift time is 430 m and 1.5 ℃/Ma,respectively.And the result reveals that the largest difference

  8. Multi-stage uplift of the Rocky Mountains: new age constraints on the Telluride Conglomerate and regional compilation of apatite fission track ages

    Science.gov (United States)

    Donahue, M. S.; Karlstrom, K. E.; Gonzales, D. A.; Pecha, M.; McKeon, R. E.

    2011-12-01

    The Telluride Conglomerate, exposed on the western flanks of Oligocene caldera complexes of the San Juan Mountains of Colorado, has historically been considered an Eocene alluvial deposit overlying the "Rocky Mountain erosion surface" and pre-dating Oligocene volcanism. Measured sections show that the Telluride preserves an unroofing sequence with basal units dominated by Paleozoic sedimentary clasts transitioning into upper units dominated by locally derived Proterozoic basement mixed with previously unrecognized andesitic Oligocene volcanics. Paleoflow directions and thicknesses of the preserved unit indicate the Telluride Conglomerate was deposited by a large, high-energy WNW- flowing braided river system. Detrital zircon analysis indicates minimum ages for individual grains within the Telluride Conglomerate of 28.0 to 31.5 Ma. This, plus the entrained volcanic clasts, redefines the unit as being of Oligocene age and indicates that conglomeratic deposition overlapped with regional San Juan volcanism and just predated major caldera eruptions at 28.4 Ma (San Juan and Uncompahgre) and 27.6 Ma (Silverton). We interpret the deposition of the Telluride Conglomerate to be the depositional response to regional uplift and erosion related to early stages of San Juan magmatism. These units have undergone significant post-depositional tectonism: the Telluride Conglomerate is found at ~9,000ft elevation near Telluride, CO, but is at ~13,000' at its westernmost exposure at Mt. Wilson. We attribute this differential uplift to be associated with faulting, pluton emplacement, and additional mantle driven uplift associated with the emplacement and cooling of the Wilson Stock in the last 20-22 Ma as documented by Miocene cooling seen in apatite helium (AHe) ages. This cooling fits into our regional compilation of published apatite fission track (AFT) and AHe data showing temporally and spatially partitioned Cenozoic cooling indicative of multistage uplift of the Rocky Mountain

  9. 磷灰石裂变径迹(AFT)研究进展%The Study Progress in Apatite Fission Track (AFT)

    Institute of Scientific and Technical Information of China (English)

    周海; 雷川

    2013-01-01

    Apatite Fission Track (AFT) is a useful tool to rebuild the low temperature thermo-chronological evolution of rocks. Recent research progress on application and methodlogy of AFT is reviewed in this contribution. We summarized the main factors related to AFT annealing behavior, including:①enrichment of certain main elements and 238U in apatites. ②alpha-decay loss. ③pressure and stress, several problems during experimental observation and the multiple annealing model. Review the previous studies, summarize pros and cons of the current annealing model and its application in analysis of the basin thermal-tectonic evolution history, and orogenic belt uplift (I. E. Tibet Plateau uplift).%磷灰石裂变径迹是一种揭示岩石低温热年代学的有力工具.通过对国内外相关文献的广泛阅读,综述了磷灰石裂变径迹分析方法的原理、研究进展和地质意义及其在相关地质领域的应用.总结了影响磷灰石裂变径迹退火行为的主要影响因素,包括:①磷灰石的主要元素及238U的富集.②α衰变亏损.③压力及应力,以及实验观察时需要注意的问题.简要介绍了关于磷灰石裂变径迹退火过程的多元退火模型的建立及控制因素.对于目前的退火模型应用情况,结合前人研究总结了目前该方法的独特性及现行退火模型的不足之处.并对磷灰石裂变径迹在关于盆地热演化史、断层研究和造山带隆升分析(主要针对青藏高原隆升分析)中的应用做了简单、概要的剖析.

  10. Deciphering Past and Present Tectonics of the Rio Grande Rift in New Mexico Utilizing Apatite Fission Track Thermochronology, Geochronology, Quaternary Faulting, and Cross-Section Restoration

    Science.gov (United States)

    Ricketts, J. W.; Karlstrom, K. E.; Kelley, S. A.; Priewisch, A.; Crossey, L. J.; Asmerom, Y.; Polyak, V.; Selmi, M.

    2011-12-01

    The Rio Grande rift provides an excellent laboratory for understanding styles and processes of extensional tectonics, and their driving forces. We apply apatite fission track (AFT) thermochronology, geochronology, fracture analysis, and cross-section restoration to decipher past and present tectonics of the Rio Grande rift. AFT data has been compiled from rift flank uplifts along the Rio Grande rift in an attempt to recognize long wavelength spatial and temporal patterns. AFT ages record time of cooling of rocks below ~110°C and, when cooling is due to exhumation, age elevation traverses can record upward advection of rocks through paleo 110°C isotherms. The relatively passive sides of half-grabens (e.g. Manzanos and Santa Fe Range) preserve Laramide AFT ages ranging from 45-70 Ma, indicating they were cooled during the Laramide Orogeny and have remained cooler than 110°C since then. Rift flanks on the tectonically active sides of half-grabens, (e.g. Sierra Ladrones, Sandias, Taos Range, and Sierra Blanca) have AFT ages that range from 35 Ma to <10 Ma, and record cooling that initiated with the Oligocene ignimbrite flare-up and continues through the Neogene. Our analysis tracks the approximate elevation of paleo 110°C isotherms in 10 Ma intervals from the Laramide to the present and shows that reconstructed paleoisotherms have been differentially uplifted, warped, and faulted since their time of formation, and hence serve as markers of uplift history and its mechanisms. AFT data at Ladron Peak, an active rift flank along the western margin of the Rio Grande rift in central New Mexico, indicates that it was rapidly unroofed between 20-10 Ma. Preliminary apatite helium data gives a similar age vs. elevation trend, but apatites have highly radiogenically damaged lattices and hence have corrected closure temperatures tens of degrees higher than AFT ages. The style of faulting at Ladron Peak is unusual because it is bounded by the anomalously low-angle (~15°) Jeter

  11. Apatite fission-track evidence for regional exhumation in the subtropical Eocene, block faulting, and localized fluid flow in east-central Alaska

    Science.gov (United States)

    Dusel-Bacon, Cynthia; Bacon, Charles R.; O'Sullivan, Paul B.; Day, Warren C.

    2016-01-01

    The origin and antiquity of the subdued topography of the Yukon–Tanana Upland (YTU), the physiographic province between the Denali and Tintina faults, are unresolved questions in the geologic history of interior Alaska and adjacent Yukon. We present apatite fission-track (AFT) results for 33 samples from the 2300 km2 western Fortymile district in the YTU in Alaska and propose an exhumation model that is consistent with preservation of volcanic rocks in valleys that requires base level stability of several drainages since latest Cretaceous–Paleocene time. AFT thermochronology indicates widespread cooling below ∼110 °C at ∼56–47 Ma (early Eocene) and ∼44–36 Ma (middle Eocene). Samples with ∼33–27, ∼19, and ∼10 Ma AFT ages, obtained near a major northeast-trending fault zone, apparently reflect hydrothermal fluid flow. Uplift and erosion following ∼107 Ma magmatism exposed plutonic rocks to different extents in various crustal blocks by latest Cretaceous time. We interpret the Eocene AFT ages to suggest that higher elevations were eroded during the Paleogene subtropical climate of the subarctic, while base level remained essentially stable. Tertiary basins outboard of the YTU contain sediment that may account for the required >2 km of removed overburden that was not carried to the sea by the ancestral Yukon River system. We consider a climate driven explanation for the Eocene AFT ages to be most consistent with geologic constraints in concert with block faulting related to translation on the Denali and Tintina faults resulting from oblique subduction along the southern margin of Alaska.

  12. Constraining the age and magnitude of uplift in the northern National Petroleum Reserve in Alaska (NPRA)-apatite fission-track analysis of samples from three wells

    Science.gov (United States)

    Houseknecht, David W.; Bird, Kenneth J.; O'Sullivan, Paul

    2011-01-01

    A broad, post-mid-Cretaceous uplift is defined in the northern National Petroleum Reserve in Alaska (NPRA) by regional truncation of Cretaceous strata, thermal maturity patterns, and amounts of exhumation estimated from sonic logs. Apatite fission-track (AFT) analysis of samples from three wells (South Meade No. 1, Topagoruk No. 1, and Ikpikpuk No. 1) across the eastern flank of the uplift indicates Tertiary cooling followed by Quaternary heating. Results from all three wells indicate that cooling, presumably caused by uplift and erosion, started about 75-65 Ma (latest Cretaceous-earliest Tertiary) and continued through the Tertiary Period. Data from South Meade indicate more rapid cooling after about 35-15 Ma (latest Eocene-middle Miocene) followed by a significant increase in subsurface temperature during the Quaternary, probably the result of increased heat flow. Data from Topagoruk and Ikpikpuk include subtle evidence of accelerated cooling starting in the latest Eocene-middle Miocene and possible evidence of increased temperature during the Quaternary. Subsurface temperature perturbations related to the insulating effect of permafrost may have been responsible for the Quaternary temperature increase at Topagoruk and Ikpikpuk and may have been a contributing factor at South Meade. Multiple lines of geologic evidence suggest that the magnitude of exhumation resulting from uplift and erosion is 5,000-6,500 ft at South Meade, 4,000-5,500 ft at Topagoruk, and 2,500-4,000 ft at Ikpikpuk. The results from these wells help to define the broad geometry of the uplift, which increases in magnitude from less than 1,000 ft at the Colville River delta to perhaps more than 7,000 ft along the northwestern coast of NPRA, between Point Barrow and Peard Bay. Neither the origin nor the offshore extent of the uplift, west and north of the NPRA coast, have been determined.

  13. Thermal modeling and geomorphology of the south border of the Sao Francisco Craton: thermochronology by fission tracks in apatites;Modelagem termica e geomorfologia da borda sul do Craton do Sao Francisco: termocronologia por tracos de fissao em apatita

    Energy Technology Data Exchange (ETDEWEB)

    Hackspacher, Peter Christian [UNESP, Rio Claro, SP (Brazil). Inst. de Geociencias e Ciencias Exatas; Godoy, Daniel Francoso de; Franco, Ana Olivia Barufi [UNESP, Rio Claro, SP (Brazil). Pos-Graduacao em Geologia Regional; Ribeiro, Luiz Felipe Brandini [NUCLEARGEO, Rio Claro, SP (Brazil); Hadler Neto, Julio Cesar [Universidade Estadual de Campinas (IFGW/UNICAMP), SP (Brazil). Inst. de Fisica Gleb Wataghin

    2007-12-15

    Recent developments in Fission Track thermochronology associated to mesozoic-cenozoic erosion and tectonic presented trough thematic maps (isotemperature), permit to model the landscape evolution in the southern border of the Sao Francisco craton, southeastern Brazil. Paleotemperature, obtained by fission track analysis in apatite, is closely related to geomorphologic interpretations. The area suffered a complex imprint of endogenous and exogenous processes resulting diversified and differentiated relieves. The landscape is strongly controlled by exhumation between Jurassic and Lower Cretaceous, uplift with tectonic denudation related to crustal heating at the Upper Cretaceous and reactivation of faults until the Miocene. This scenario is a result of reactivations of different brittle structures that accommodate the deformation in the southern border of the Sao Francisco craton. The landscape reflects denudations of up to 3 km with preserved remains of erosive surfaces in the topographical tops and chronocorrelates deposits in the basins of the region. (author)

  14. Tectonic and thermal history of the western Serrania del Interior foreland fold and thrust belt and Guarico Basin, north central Venezuela: Implications of new apatite fission track analysis and seismic interpretation

    Science.gov (United States)

    Perez de Armas, Jaime Gonzalo

    Structural analysis, interpretation of seismic reflection lines, and apatite fission-track analysis in the Western Serrania del Interior fold and thrust belt and in the Guarico basin of north-central Venezuela indicate that the area underwent Mesozoic and Tertiary-to-Recent deformation. Mesozoic deformation, related to the breakup of Pangea, resulted in the formation of the Espino graben in the southernmost portion of the Guarico basin and in the formation of the Proto-Caribbean lithosphere between the diverging North and South American plates. The northern margin of Venezuela became a northward facing passive margin. Minor normal faults formed in the Guarico basin. The most intense deformation took place in the Neogene when the Leeward Antilles volcanic island arc collided obliquely with South America. The inception of the basal foredeep unconformity in the Late Eocene-Early Oligocene marks the formation of a perisutural basin on top of a buried graben system. It is coeval with minor extension and possible reactivation of Cretaceous normal faults in the Guarico basin. It marks the deepening of the foredeep. Cooling ages derived from apatite fission-tracks suggest that the obduction of the fold and thrust belt in the study area occurred in the Late Oligocene through the Middle Miocene. Field data and seismic interpretations suggest also that contractional deformation began during the Neogene, and specifically during the Miocene. The most surprising results of the detrital apatite fission-track study are the ages acquired in the sedimentary rocks of the easternmost part of the study area in the foreland fold and thrust belt. They indicate an Eocene thermal event. This event may be related to the Eocene NW-SE convergence of the North and South American plates that must have caused the Proto-Caribbean lithosphere to be shortened. This event is not related to the collision of the arc with South America, as the arc was far to the west during the Eocene.

  15. Cretaceous-Cenozoic tectonic history of the Jiaojia Fault and gold mineralization in the Jiaodong Peninsula, China: constraints from zircon U-Pb, illite K-Ar, and apatite fission track thermochronometry

    Science.gov (United States)

    Deng, Jun; Wang, Changming; Bagas, Leon; Carranza, Emmanuel John M.; Lu, Yongjun

    2015-12-01

    The Jiaojia Fault (JJF) in the Jiaodong area of eastern China is an important NNE-trending structure that is subsidiary to the regional Tancheng-Lujiang (Tan-Lu) Fault Zone, and hosts >1200 t of gold reserves contained in disseminated and stockwork ore, dominantly in the footwall of the fault. We present new zircon U-Pb, apatite fission track, and illite K-Ar data along the JJF and have delineated its tectonic history focusing on its formation and reactivation. Zircon U-Pb dating shows that the Shangzhuang granite is a composite body with ages between 132 ± 1 and 127 ± 1 Ma. Illite K-Ar ages for the fault's gouge range from 83 ± 2 to 68 ± 2 Ma, and the measured apatite fission track ages for ores are between 55 and 21 Ma. Previous zircon U-Pb geochronology and structural studies suggest that the JJF was originally activated in the Jurassic during 160-150 Ma as a sinistral fault. The JJF was a normal fault in the Early Cretaceous due to NW-SE orientated tension and NE-SW compression, which lasted from 135 to 120 Ma. This was followed by sinistral strike-slip faulting due to NW-SE compression and NE-SW tension during 120-110 Ma, and it changed to normal displacement at ca. 110 Ma. Our apatite fission track data analysis and thermal modeling of representative samples suggest that there was a subsequent dextral reactivation of the fault at ca. 55 Ma. Previous age data of ca. 130-110 Ma for gold mineralization along the JJF coincides with the Early Cretaceous magmatism and is coeval with the transition from normal faulting to sinistral strike-slip faulting of the JJF in Early Cretaceous, which is interpreted to be due to changing direction of the subducting Pacific Plate.

  16. Fission-track ages from the Precambrian of Shropshire.

    Science.gov (United States)

    Naeser, C.W.; Toghill, P.; Ross, R.J.

    1982-01-01

    Four samples of Longmyndian and Uriconian strata from S of Shrewsbury, England have been processed for apatite and/or zircon fission-track ages. The resultant ages illustrate how depth of burial may affect fission-track ages. The analytical procedures followed were as described in Naeser (1979).-from Authors

  17. A Modern Analog to the Depositional Age Problem: Zircon and Apatite Fission Track and U-Pb Age Distributions by LA-ICP-MS

    Science.gov (United States)

    Donelick, H. M.; Donelick, M. B.; Donelick, R. A.

    2012-12-01

    Sand from three river systems in North Idaho (Snake River near Lewiston, Clearwater River near Lewiston and the Salmon River near White Bird) and two regional ash fall events (Mt. Mazama and Mt. St. Helens) were collected for zircon U-Pb detrital age analysis. Up to 120 grains of zircon per sample were ablated using a Resonetics M-50 193 nm ArF Excimer laser ablation (LA) system and the Pb, Th, and U isotopic signals were quantified using an Agilent 7700x quadrupole inductively coupled plasma-mass spectrometer (ICP-MS). Isotopic signals for major, minor, and trace elements, including all REEs, were also monitored. The youngest zircon U-Pb ages from the river samples were approximately 44 Ma; Cenozoic Idaho Batholith and Precambrian Belt Supergroup ages were well represented. Significant common Pb contamination of the Clearwater River sample (e.g., placer native Cu was observed in the sample) precluded detailed analysis of the zircon U-Pb ages but no interpretable ages <44 Ma were observed. Interestingly, not one of the river samples yielded zircon U-Pb ages near 0 Ma, despite all three catchment areas having received significant ash from Mt. St. Helens in 1980, and Mount Mazama 7,700 years ago, and no doubt other events during the Quaternary. Work currently in progress seeks to address bias against near 0 Ma ages in the catchment areas due to: a) small, local ash fall grain sizes and b) overwhelming number of older grains relative to the ash fall grains. Data from Mt. St. Helens ash from several localities near the mountain (Toutle River and Maple Flats, WA) and several far from the mountain (Spokane, WA; Princeton, ID; Kalispell, MT) and Mt. Mazama ash fall deposits near Lewiston, ID and Spokane, WA will be presented to address these possibilities. Additionally, fission track and U-Pb ages from apatites collected from these river and ash fall samples will also be shown to help constrain the problem.

  18. The Application of Apatite Fission Track in Determining the Tectonic Uplift Rates%磷灰石裂变径迹在确定造山带隆升速率中的应用

    Institute of Scientific and Technical Information of China (English)

    刘海青; 李荣西; 张艳妮; 朱德明; 朱瑞静; 王宁; 赵帮胜

    2014-01-01

    矿物裂变径迹技术是一种低温热史及年代学测定技术,广泛应用于含油气盆地热史分析、沉积物来源、造山带隆升剥蚀、地质年代学测定等方面的研究。近年来,磷灰石裂变径迹在研究造山带构造隆升速率方面取得了大量成果。笔者在结合前人研究成果基础上,分别介绍了利用裂变径迹反演热史、裂变年龄和矿物对-封闭温度法确定构造隆升速率的原理、方法和应用,并分析其优缺点,指出应用磷灰石裂变径迹研究构造隆升速率时应该注意的问题。%Mineral fission track is a kind of measurement technology for low temperature thermal history and chronology,which is widely used in analysis of oil and gas basin thermal history,the source of sediments,the uplift and denudation of orogenic belt,the geochronology measurement and so on.In recent years,apatite fission track has got lots of achievements in the tectonic uplift rates study of orogenic belt.Based on previous fission track analysis researches,this article respectively introduces the use of fission track to invert thermal history,fission age and minerals to closed temperature method to determine the tectonic uplift rates of principle and method and application.At the same time the paper analyzes its advantages and disadvantages,pointing out the problems need to be considered when applying apatite fission track to study tectonic uplift rates.

  19. The chronology and tectonic style of landscape evolution along the elevated Atlantic continental margin of South Africa resolved by joint apatite fission track and (U-Th-Sm)/He thermochronology

    Science.gov (United States)

    Wildman, Mark; Brown, Roderick; Beucher, Romain; Persano, Cristina; Stuart, Fin; Gallagher, Kerry; Schwanethal, James; Carter, Andrew

    2016-03-01

    Atlantic-type continental margins have long been considered "passive" tectonic settings throughout the entire postrift phase. Recent studies question the long-term stability of these margins and have shown that postrift uplift and reactivation of preexisting structures may be a common feature of a continental margin's evolution. The Namaqualand sector of the western continental margin of South Africa is characterized by a ubiquitously faulted basement but lacks preservation of younger geological strata to constrain postrift tectonic fault activity. Here we present the first systematic study using joint apatite fission track and apatite (U-Th-Sm)/He thermochronology to achieve a better understanding on the chronology and tectonic style of landscape evolution across this region. Apatite fission track ages range from 58.3 ± 2.6 to 132.2 ± 3.6 Ma, with mean track lengths between 10.9 ± 0.19 and 14.35 ± 0.22 µm, and mean (U-Th-Sm)/He sample ages range from 55.8 ± 31.3 to 120.6 ± 31.4 Ma. Joint inverse modeling of these data reveals two distinct episodes of cooling at approximately 150-130 Ma and 110-90 Ma with limited cooling during the Cenozoic. Estimates of denudation based on these thermal histories predict approximately 1-3 km of denudation coinciding with two major tectonic events. The first event, during the Early Cretaceous, was driven by continental rifting and the development and removal of synrift topography. The second event, during the Late Cretaceous, includes localized reactivation of basement structures as well as regional mantle-driven uplift. Relative tectonic stability prevailed during the Cenozoic, and regional denudation over this time is constrained to be less than 1 km.

  20. The mesozoic-cenozoic tectonics of part of the northeastern margin of the Parana Basin: apatite fission tracks; A tectonica meso-cenozoica de parte da borda nordeste da Bacia do Parana: tracos de fissao em apatita

    Energy Technology Data Exchange (ETDEWEB)

    Fracalossi, Carlos Pinto [PETROBRAS (Brazil). Unidade de Negocio Sergipe Alagoas. Gerencia de Avaliacao e Acompanhamento Geologico], e-mail: carlos.fracalossi@petrobras.com.br; Godoy, Daniel Francoso [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Rio Claro, SP (Brazil). Pos-Graduacao em Geologia Regional], e-mail: dfgodoy@gmail.com; Hackspacher, Christian [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Rio Claro, SP (Brazil). Dept. de Petrologia e Metalogenia

    2007-11-15

    The possible development of thermal events in the central portion of Sao Paulo state was described based on apatite fission track analysis. Using apatites of sedimentary rocks of the Parana Basin, modeling the thermal history was made possible due to the homogeneity of the data. Every thermal history begins with a total annealing of fission tracks, related to the Serra Geral magmatism, evolving into a cooling period. In addition to cooling after the magmatism (Early Cretaceous) two other periods of cooling were also detected, registered in the Late Cretaceous/Paleocene and Eocene, driven as much by uplift with tectonic denudations by faulting. The nearest portion of the edge of the basin (external to the Dome of Pitanga), registered a period of warming over the Paleocene that can be attributed to the increase in the geothermal gradient. The periods of cooling have a regional and temporal relationship with the tectonic events that occurred in the southeastern Brazil and were described in the crystalline basement. The period of warming, registered in the Late Cretaceous/Paleocene, has local occurrence and can be found only in the southern portion of the studied area. (author)

  1. Apatite fission-track thermochronological constraints on the pattern of late Mesozoic-Cenozoic uplift and exhumation of the Qinling Orogen, central China

    Science.gov (United States)

    Chen, Hong; Hu, Jianmin; Wu, Guoli; Shi, Wei; Geng, Yingying; Qu, Hongjie

    2015-12-01

    The Qinling Orogen of central China was formed by intracontinental collision between the North and South China Blocks. The orogen comprises several micro-blocks bounded by sutures and faults, and has undergone long-term intracontinental deformation since the Late Triassic. The micro-blocks include the southern margin of the North China Block (S-NCB), the Northern Qinling Belt (NQB), the Southern Qinling Belt (SQB), and the northern margin of the South China Block (N-SCB). Under a uniform tectonic setting in late Mesozoic-Cenozoic, these micro-blocks have been subjected to a range of deformation styles, as demonstrated by their structural deformation, history of magmatism, and the development of sedimentary basins. To investigate the differences among the micro-blocks and to quantify their uplift and exhumation, we obtained 45 rock samples from eight Mesozoic granites in these micro-blocks, and conducted apatite fission-track (AFT) thermochronological modeling. The results reveal that the Qinling Orogen underwent four distinct stages of rapid cooling histories during the late Mesozoic-Cenozoic, and showed variation in uplift and exhumation whereby the intracontinental deformation started in the south (the N-SCB) and propagated to the north (S-NCB). In the first stage, during the Late Jurassic-Early Cretaceous (ca. 160-120 Ma), rock cooling occurred mainly in the N-SCB, attributed to the clockwise rotation and northward subduction of the South China Block beneath the Qinling Orogen. In the second stage, compression- and extension-related uplift was initiated during the late Early Cretaceous-early Late Cretaceous (ca. 120-90 Ma) in the SQB, consistent with the southward subduction of the North China Block and broadly extensional deformation in the eastern China continent. In the third stage, a gentle regional-scale cooling event that occurred during the latest Cretaceous-Paleocene (ca. 90-50 Ma) started in the NQB and became widespread in the Qinling Orogen. This

  2. Evolution of the South Atlantic passive continental margin and lithosphere dynamic movement in Southern Brazil derived from zircon and apatite (U-Th-Sm)/He and fission-track data

    Science.gov (United States)

    Krob, Florian; Stippich, Christian; Glasmacher, Ulrich A.; Hackspacher, Peter C.

    2016-04-01

    Passive continental margins are important geoarchives related to mantle dynamics, the breakup of continents, lithospheric dynamics, and other processes. The main concern yields the quantifying long-term lithospheric evolution of the continental margin between São Paulo and Laguna in southeastern Brazil since the Neoproterozoic. We put special emphasis on the reactivation of old fracture zones running into the continent and their constrains on the landscape evolution. In this contribution, we represent already consisting thermochronological data attained by fission-track and (U-Th-Sm)/He analysis on apatites and zircons. The zircon fission-track ages range between 108.4 (15.0) and 539.9 (68.4) Ma, the zircon (U-Th-Sm)/He ages between 72.9 (5.8) and 427.6 (1.8) Ma whereas the apatite fission-track ages range between 40.0 (5.3) and 134.7 (8.0) Ma, and the apatite (U-Th-Sm)/He ages between 32.1 (1.52) and 92.0 (1.86) Ma. These thermochronological ages from metamorphic, sedimentary and intrusive rocks show six distinct blocks (Laguna, Florianópolis, Curitiba, Ilha Comprida, Peruibe and Santos) with different evolution cut by old fracture zones. Furthermore, models of time-temperature evolution illustrate the differences in Pre- to post-rift exhumation histories of these blocks. The presented data will provide an insight into the complex exhumation history of the continental margin based on the existing literature data on the evolution of the Paraná basin in Brazil and the latest thermochronological data. We used the geological model of the Paraná basin supersequences (Rio Ivaí, Paraná, Gondwana I-III and Bauru) to remodel the subsidence and exhumation history of our consisting thermochronological sample data. First indications include a fast exhumation during the early Paleozoic, a slow shallow (northern blocks) to fast and deep (Laguna block) subduction from middle Paleozoic to Mesozoic time and a extremely fast exhumation during the opening of the South Atlantic

  3. Detrital zircon and apatite fission track data in the Liaoxi basins: Implication to Meso-Cenozoic thermo-tectonic evolution of the northern margin of the North China Craton

    Indian Academy of Sciences (India)

    Yi Yan; Xiaoqiong Hu; Ge Lin; Weiliang Liu; Zhengjiang Song

    2010-08-01

    Detrital zircon and apatite fission track (ZFT and AFT) data of the sandstones collected from the Liaoxi basins served as a significant probe to study the Meso-Cenozoic thermo-tectonic reactivation events in the northern margin of the North China Craton. All sandstones show wide ZFT and AFT age spectrum and most of ZFT and AFT ages are younger than depositional age of respective host rocks, which suggest widespread track resetting of the host rocks in the Liaoxi basins after deposition. This hot geothermal status in the Liaoxi basins deduced from ZFT and AFT data is temporal consistent with the lithospheric evolution of the North China Craton, which implies that the lithosphere under the northern margin of the North China Craton underwent similar thermo-tectonic destruction process as the intracratonic Bohai Sea. The young ZFT peak age, which ranges from ∼50Ma to 20 Ma, to some extend, provides a temporal constraint on the time that lithosphere significantly thinned and following reverse of the Liaoxi basins and uplift of the eastern part of the Yan-Liao Orogenic Belt. Exhumation of 1.5–2 km can be estimated in the eastern part of the Yan-Liao Orogenic Belt since ∼30Ma to 10 Ma.

  4. A refinement of the chronology of rift-related faulting in the Broadly Rifted Zone, southern Ethiopia, through apatite fission-track analysis

    Science.gov (United States)

    Balestrieri, Maria Laura; Bonini, Marco; Corti, Giacomo; Sani, Federico; Philippon, Melody

    2016-03-01

    To reconstruct the timing of rift inception in the Broadly Rifted Zone in southern Ethiopia, we applied the fission-track method to basement rocks collected along the scarp of the main normal faults bounding (i) the Amaro Horst in the southern Main Ethiopian Rift and (ii) the Beto Basin in the Gofa Province. At the Amaro Horst, a vertical traverse along the major eastern scarp yielded pre-rift ages ranging between 121.4 ± 15.3 Ma and 69.5 ± 7.2 Ma, similarly to two other samples, one from the western scarp and one at the southern termination of the horst (103.4 ± 24.5 Ma and 65.5 ± 4.2 Ma, respectively). More interestingly, a second traverse at the Amaro northeastern terminus released rift-related ages spanning between 12.3 ± 2.7 and 6.8 ± 0.7 Ma. In the Beto Basin, the ages determined along the base of the main (northwestern) fault scarp vary between 22.8 ± 3.3 Ma and 7.0 ± 0.7 Ma. We ascertain through thermal modeling that rift-related exhumation along the northwestern fault scarp of the Beto Basin started at 12 ± 2 Ma while in the eastern margin of the Amaro Horst faulting took place later than 10 Ma, possibly at about 8 Ma. These results suggest a reconsideration of previous models on timing of rift activation in the different sectors of the Ethiopian Rift. Extensional basin formation initiated more or less contemporaneously in the Gofa Province (~ 12 Ma) and Northern Main Ethiopian Rift (~ 10-12 Ma) at the time of a major reorganization of the Nubia-Somalia plate boundary (i.e., 11 ± 2 Ma). Afterwards, rift-related faulting involved the Southern MER (Amaro Horst) at ~ 8 Ma, and only later rifting seemingly affected the Central MER (after ~ 7 Ma).

  5. Apatite fission track evidence for the Cretaceous-Cenozoic cooling history of the Qilian Shan (NW China) and for stepwise northeastward growth of the northeastern Tibetan Plateau since early Eocene

    Science.gov (United States)

    Qi, Bangshen; Hu, Daogong; Yang, Xiaoxiao; Zhang, Yaoling; Tan, Chengxuan; Zhang, Peng; Feng, Chengjun

    2016-07-01

    Apatite fission track (AFT) data from hinterland of the Qilian Shan at the northeastern margin of the Tibetan Plateau suggest this range has experienced northeastward propagation of surface uplift since early Eocene and that crustal shortening occurred in the Qilian Shan before the late Miocene. Thermochronometry data indicate that the Qilian Shan experienced a three-stage cooling history, including: (1) rapid initial cooling during Cretaceous; (2) a stage of slow cooling during late Cretaceous-early Eocene; and (3) rapid stepwise cooling in a southwestern-northeastern orientation since early Eocene. Cretaceous rapid cooling may be a record of the Lhasa block and Eurasian collision. Early Cretaceous denudation was followed by tectonic and quasi-isothermal quiescence that continued until early Eocene. Early Eocene rapid cooling in the South Qilian Shan may be the first far-field response in the Qilian Shan to the collision and convergence of the Indian and Eurasian continents. From late Eocene to middle Miocene, crustal shortening propagated into the Central Qilian Shan and North Qilian Shan and produced surface uplift of the entire Qilian Shan region before the late Miocene. This study provides a better understanding of the tectonic evolution of the Qilian Shan and when the far-field stress from the India-Eurasia collision into the northeastern Tibetan Plateau began.

  6. Thermo-tectonics of the Calabrian Arc, southern Italy: Constraints from fission track analysis

    Science.gov (United States)

    Thomson, Stuart Nigel

    This study uses fission track analysis to provide temperature and time constraints on the cooling and exhumation history of the basement rocks of the Calabrian Arc of southern Italy. Fission track analysis also provides information on the provenance and burial history of the terrigenous Oligo-Miocene Stilo-Capo d'Orlando Formation. 65 samples from the basement rocks have yielded 57 apatite fission track ages, 54 zircon fission track ages and 25 apatite track length distributions. 9 samples from the Stilo- Capo d'Orlando Formation have yielded 8 apatite fission track ages, 8 zircon fission track ages and 6 apatite track length distributions. Qualitative and quantitative analysis of the fission track data reveals that the majority of the basement rocks underwent a phase of increased cooling related to exhumation between about 35 Ma (Early Oligocene) and 15 Ma (Middle Miocene). Evidence from the local sedimentary record indicates that erosion played an important role in the exhumation process. Extensional tectonism also contributes to some of the increased exhumation. Analysis of the fission track results obtained from the Stilo-Capo d'Orlando Formation confirm a Calabrian basement provenance for the sediments. The previously debated origin of volcanic conglomerate clasts from the formation is also resolved. Finally apatite fission track analysis indicates post-depositional burial at the base of the formation to temperatures greater than 80° C. The final part of this thesis uses the fission track age and temperature constraints to produce an improved tectonic model for the Oligo-Miocene tectonic evolution of the Calabrian Arc. This model proposes that increased exhumation is a consequence of the dynamics of an overthickened orogenic wedge. The model is related to the overall plate dynamics of the western Mediterranean orogeny.

  7. Cenozoic uplift of West Qinling, northeast margin of Tibetan plateau-a detrital apatite fission track record from the Tianshui basin

    Institute of Scientific and Technical Information of China (English)

    WANG Xiuxi; LI Jijun; SONG Chunbui; ZHANG Jun; ZHAO Zhijun; GAO Junping; PAN Meihui

    2007-01-01

    The Cenozoic sedimentation in the Tianshui basin, which is located at the junction of the Liupanshan and West Qinling, northeast margin of the Tibetan plateau,provides a record for the regional tectonism and exhumation history of the surrounding mountains. Thermochronologic study on the detrital apatite grains from sandstones at Yaodian, near Tianshui, has revealed two rapid tectonic uplift-exhumation events of the source area, which happened at 23.7 and 14.1 Ma, respectively. The fast exhumation(0.34 mm/a) at 23.7 Ma, which recorded the tectonic uplift ofWest Qinling, led to the formation of the Neogene Tianshuibasin and initiated the reception of alluvial deposits. This event is most likely in response to the synchronous tectonism of the Tibetan plateau. The source region experienced another rapid exhumation (1.05 mm/a) at 14.1 Ma, when the Tianshui basin began to depress broadly and fluvial-lacustrine sediments dominated the Late Miocene.

  8. Dating thermal events at Cerro Prieto using fission track annealing

    Energy Technology Data Exchange (ETDEWEB)

    Sanford, S.J.; Elders, W..

    1981-01-01

    Data from laboratory experiments and geologic fading studies were compiled from published sources to produce lines of iso-annealing for apatite in time-temperature space. Fission track ages were calculated for samples from two wells at Cerro Prieto, one with an apparently simple and one with an apparently complex thermal history. Temperatures were estimated by empirical vitrinite reflectance geothermometry, fluid inclusion homogenization and oxygen isotope equilibrium. These estimates were compared with logs of measured borehole temperatures.

  9. Differential denudations of the Argentera Alpine external crystalline massif (SE France) revealed by fission track thermo-chronology (zircons, apatites); Denudations differentielles du massif cristallin externe alpin de l'Argentera (Sud-Est de la France) revelees par thermochronologie traces de fission (apatites, zircons)

    Energy Technology Data Exchange (ETDEWEB)

    Bigot-Cormier, F.; Sosson, M. [Centre National de la Recherche Scientifique (CNRS-UMR 6526), Geosciences Azur, 06 - Valbonne (France); Poupeau, G. [Maison des Geosciences, 38 - Grenoble (France)

    2000-03-01

    A fission track thermo-chronological study of the Argentera external crystalline massif (western Alps) reveals tectonic blocks with differential vertical motions. The northwest area cooled down about 300 deg. C from the Upper Cretaceous and the remaining of the massif crossed the 250 deg. C isotherm in the 29-20 Ma time interval, after the internal nappe over-thrust. Moreover the massif cooled below 120 deg. C more than 12.5 Ma ago and its denudation rate increased locally 6 Ma ago and more generally since 3.5 Ma in relation with the reverse motion along the Bersezio fault. (authors)

  10. Apatite fission-track records of Mesozoic and Cenozoicepisodic reactivation of the Tianshan and West Kunlun Mountains%天山、西昆仑山中、新生代幕式活动的磷灰石裂变径迹记录

    Institute of Scientific and Technical Information of China (English)

    王彦斌; 王永; 刘训; 傅德荣; 王军; 王世成

    2001-01-01

    The low-temperature (i.e. <110℃) thermal history of the Tianshan and West Kunlun Mountains has been studied by apatite fission track analysis of 7 granite outcrop samples. Fission-track ages for these samples range from 9.6±0.8 to 89.2±2.3 Ma with mean track lengths varying from 7.9±3.7 to 11.6±1.9 μm. The apatite fission track ages from various geographical regions suggest difference in styles of cooling during the Mesozoic-Cenozoic. The geological and apatite fission-track data from the Tianshan and West Kunlun indicate that there occurred an uplift the Tianshan in the Cretaceous and another uplift in the Tianshan and West Kunlun in the Miocene.%通过对天山独山子—库车公路、西昆仑山新疆—西藏公路出露的7个花岗岩样品的磷灰石裂变径迹分析,研究了天山、西昆仑山脉低温(<110℃)热历史。磷灰石裂变径迹年龄范围为(9.6±0.8)~(89.2±2.3)Ma,平均裂变径迹长度变化范围为(7.9±3.7)~(11.6±1.9)μm。磷灰石裂变径迹年龄反映冷却作用时代,地质资料和磷灰石裂变径迹分析数据表明,天山在白垩纪存在一次抬升作用,天山和西昆仑山在中新世发生另一次抬升作用。

  11. Meso-Cenozoic uplifting and exhumation on Yunkaidashan: Evidence from fission track thermochronology

    Institute of Scientific and Technical Information of China (English)

    LI Xiaoming; WANG Yuejun; TAN Kaixuan; PENG Touping

    2005-01-01

    Yunkaidashan, located at the southern South China block (SCB) and closely adjacent to the Indochina block, is an ideal region for better understanding the temporal and spatial framework of tectonothermal overprinting at the southern SCB since Mesozoic. Apatite and zircon fission track thermochronology of various-type rocks from Yunkaidashan is presented in this paper. The results show, no matter what rocks are, the apparent ages of zircon fission track range from 97.4 to 133.0 Ma, and those of apatite fission track from 43.2 to 68.4 Ma. The length of apatite fission track yields an average confined track length of ~13 μm and shows normal distribution of unimodal frequency. It is inferred that the uplifting amplitude has been more than 5 km in Yunkaidashan since late Mesozoic. The difference of fission track apparent ages at different locations in Yunkaidashan suggests a paleophysiognomic scenario of the heterogeneous uplift/denudation. These data of the fission track thermochronology provide new constraints for better understanding the tectonophysiognomic pattern of the SCB since late Mesozoic.

  12. MESOZOIC AND CENOZOIC UPLIFT-DENUDATION ALONG THE ALTYN TAGH FAULT,NORTHWESTERN CHINA: CONSTRAINTS FROM APATITE FISSION TRACK DATA%阿尔金断裂带中段中新生代隆升历史分析:裂变径迹年龄制约

    Institute of Scientific and Technical Information of China (English)

    张志诚; 郭召杰; 李建锋; 汤文豪

    2012-01-01

    The study area lies between latitudes 37°30'N and 40°20'N, and longitudes 86°00'E and 95°20'E, along the northwest margin of Qinghai-Tibetan Plateau. We has carried out zircon and apatite fission track analysis from sixteen samples of the Jurassic sandstones, granites, rhyolite and Neogene granitic breccias, along the Altyn Tagh Fault(ATF) between Tula and Subei. The zircon fission track ages of four Jurassic sandstone samples range from 115. 6±18. 3Ma to 179. 4 ±19. 7Ma. The zircon data show that all but one of the zircon ages represents a Jurassic cooling event. The apatite fission track ages range between 107. 2 ±9. 0Ma and 14. 1 ±1. 3Ma, showing a general increasing trend with distance from the western part at Tula to eastern area at Subei,and all are significantly younger than their host rock formation or sediment deposition ages. The confined mean track lengths of the samples range from 11. 3 ±0. 7μm to 13. 3 ±0. 2μm,with standard deviations between 1. 8μm and 2. 9μm. All of the samples can also be divided into two broad groups depending on their apatite fission track ages and structural position. Group A refers to samples with apatite fission track ages lower than 50Ma, mostly structurally associated with the southern side of ATF. Group B refers to samples with apatite fission track ages about or older than 50Ma, generally associated with areas on the northern side of the ATF or/and on the block between the main and a secondary fault at the growing triple junction site. Modelling of the apatite fission track data (Group A) from the granites and Jurassic sedimentary strata exposed on the 9outhem side of the Altyn Tagh fault show a two-stage regional cooling history during Cenozoic. The earliest cooling phase occurred at 33Ma,and the second phase of cooling took place from about 8 Ma. The thermal models of the apatite fission track (Group B)from the granite and granitic gravels on the northern side of the ATF show a period of slow cooling during

  13. Mesozoic-Cenozoic Tectonic Evolution of the Kuqa Basin:Evidence from Apatite Fission-Track Data%库车盆地中新生代构造演化:磷灰石裂变径迹证据

    Institute of Scientific and Technical Information of China (English)

    罗梦; 朱文斌; 郑碧海; 朱晓青

    2012-01-01

    Fourteen samples were collected from the Kuqa River section for apatite fission track analysis in order to investigate the thermal history of the Kuqa Basin and its sedimentary provenance. By comparing the apparent ages of samples with the related strata ages, the samples can be divided into two groups: the annealed group and the detrital group (unreset samples). The AFT ages become younger from 136 Ma to 93. 7 Ma from the Tianshan Mountain to the Kuqa Basin, probably recording a basin-ward propagation of the thrust-fold belt. Samples 09dk-6, 09dk-7, 09dk-8 and 09dk-ll failed the X2 test likely due to the subsequent tectonic deformation. The youngest ages extracted from these samples probably record the latest activities of the Kuruli Syncline, Jiesidelike Anticline and the A'ge Fault at 74. 4 Ma, 24. 2 Ma and 50. 8 Ma, respectively. The detrital samples have three peak ages at 250 Ma, 160 Ma and 100 Ma respectively. Thermal history modeling reveals four periods of denudation at 250 Ma, 160 Ma, 100 Ma and 20 Ma in the Kuqa basin and the Tianshan Mountains. The multi-stage denudation is linked to far-field effects resulted from the collision and accretion of terranes along the southern Asian continental margin.%通过对库车河剖面14个样品磷灰石裂变径迹的测试,研究了库车盆地及其源区的构造演化.根据表观年龄和地层年龄关系,将结果分成8个退火样品和6个碎屑样品.退火样品年龄从北向南从136~93.7Ma,记录了构造发育自造山带向盆地扩展的运动样式.其中09dk-6,09dk-7,09dk-8和09dk-11未通过x2检验,分析认为与后期构造活动有关,分解得到最年轻的年龄组记录了库如力向斜,捷斯德里克背斜和阿合断层分别在74.4Ma、24.2 Ma和50.8 Ma的最新一期活动.碎屑磷灰石得到了250Ma、160Ma和100 Ma3个明显的静态峰.结合热模拟研究表明,研究区存在250Ma、160Ma、100Ma和20 Ma四期构造隆升,是对亚洲南缘多期地体碰撞增生的响应.

  14. Reconstruction of the Phanerozoic tectono-thermal history of central and southern Madagascar, based on fission track thermochronology

    OpenAIRE

    Emmel, Benjamin

    2004-01-01

    Titanite and apatite fission track (FT) thermochronology on 127 basement and 18 sedimentary rock samples from central and southern Madagascar record a complex cooling and denudation history since the Early Palaeozoic. Titanite FT analyses gave ages ranging between 483 Ma and 266 Ma. Apatite FT ages vary between 460 Ma and 79 Ma. Samples from Late Carboniferous to Jurassic sediments from the Morondava basin gave apatite FT ages ranging between 462 Ma and 184 Ma. FT data argues for reactivation...

  15. Apatite as a Tool for Tracking Magmatic CO2 Contents

    Science.gov (United States)

    Riker, J.; Humphreys, M.; Brooker, R. A.

    2014-12-01

    CO2 plays a fundamental role in the evolution of magmatic and volcanic systems, but its low solubility in silicate melts means that direct records of magmatic CO2 concentrations remain elusive. The phosphate mineral apatite is unique among igneous minerals in its capacity to accommodate all major magmatic volatiles (H2O, F, Cl, CO2 and S). Although interest in apatite as a tool for tracking magmatic volatile contents (namely H2O, F, and Cl) has increased in recent years, its potential as a record of magmatic CO2contents remains untapped. We present the results of high-temperature, high-pressure experiments investigating the partitioning behaviour of CO2 between apatite and basaltic melt. Experiments were run in piston cylinder apparatus at 1 GPa and 1250 °C, with a slow initial cooling ramp employed to facilitate crystal growth. Each charge contained the starting basaltic powder doped with Ca-phosphate and variable proportions of H2O, CO2, and F. Run products are glass-rich charges containing 15-25 vol% large, euhedral apatite crystals (± cpx and minor biotite). Experimental apatites and glasses have been characterised by BSE imaging, electron microprobe, and ion microprobe. Apatites range in composition from near-endmember fluorapatite (3.0 wt% F), to near-endmember hydroxyapatite (1.7 wt% H2O), to carbon-rich apatite containing up to 1.6 wt% CO2. Apatite compositions are stoichiometric if all anions (F-, OH-, and CO32—) lie in the channel site, suggesting an "A-type" substitution under these conditions (i.e. CO32— + [] = 2X—, where X is another channel anion and [] is a vacancy; e.g. Fleet et al. 2004). Importantly, CO2 partitions readily into apatite at all fluid compositions considered here. CO2 is also more compatible in apatite than water at our run conditions, with calculated H2O-CO2 exchange coefficients close to or greater than 1. Our results indicate that when channel ions are primarily occupied by H2O and CO2 (i.e. F- and Cl-poor magmatic systems

  16. 山西吕梁山地区中-新生代隆升剥露过程:磷灰石裂变径迹证据%Mesozoic-Cenozoic Uplift-exhumation History in Luliangshan Area of Shanxi:Evidences from Apatite Fission Track

    Institute of Scientific and Technical Information of China (English)

    任星民; 朱文斌; 朱晓青; 王玺; 罗梦

    2015-01-01

    运用磷灰石裂变径迹热年代学方法研究了华北克拉通吕梁山地区前寒武系杂岩体及其周边盆地的构造热演化过程,这对于进一步探讨和认识华北克拉通演化和破坏等科学问题有重要意义.结果表明:山西吕梁山地区磷灰石裂变径迹年龄分布于40~138 Ma,记录了吕梁山地区早白垩世以来的冷却事件;裂变径迹年龄与海拔高程呈正相关关系,线性相关系数为0.789;磷灰石颗粒的围限径迹长度范围为10.62~12.99μm,远小于其初始长度(16.3μm),表明样品经历了长期的退火过程.磷灰石裂变径迹时间-温度模拟结果表明吕梁山地区经历了两期快速隆升:第1期冷却事件对应晚侏罗世—早白垩世吕梁山山体发生的剧烈冷却抬升,该事件使得样品进入部分退火带,随后长期处于部分退火带;第2期则表现为渐新世以来吕梁山地区出现伸展造山运动,与山西地堑系形成盆山耦合,山体快速隆升剥蚀.此外,中新世末(约9 Ma)以来,青藏高原快速隆升向东扩展的远程效应对吕梁山地区构造的影响不明显.%Tectonic-thermal evolution processes of Precambrian complex in Luliangshan area of North China Craton and its peripheral basin were studied by the means of apatite fission track thermochronology in order to further discuss and recognize the evolution and breakup of North China Craton.The results show that the apatite fission track ages in Luliangshan area of Shanxi are 40-138 Ma,recording the cooling events since Early Cretaceous;fission track ages are positively correlated with the altitudes,and the correlation coefficient is 0.789;the confined track lengths of apatite particles (10.62-12.99 μm)are much shorter than the original length (16.3μm),indicating that the samples suffer a long annealing process.The time-temperature simulation results of apatite fission track show that there are two rapid uplifts in Luliangshan area.For the

  17. Detrital apatite fission track analysis and geomorphologic evolution of the Nujiang River area%怒江河砂岩屑磷灰石裂变径迹结果与流域地貌演化

    Institute of Scientific and Technical Information of China (English)

    孙东霞; 季建清; 刘一多; 李宝龙; 陈建军; 钟大赉

    2013-01-01

    River sand as an averaged product of catchment can reflect the regional thermal histories of the entire river basin. Sampling in different segments of one river is able to obtain more accurate information of the thermal history evolutions. Seven detrital sand samples were collected from different locations of the Nujiang River in western Yunnan to attempt to reveal the thermal history of the entire river basin through the apatite fission track( AFT) method. The samples show the main age peaks of 12. 2 Ma, 12. 8 Ma, 7. 7 Ma, 5. 3 Ma, 4. 4 Ma, 4. 9 Ma, 7.3 Ma respectively, presenting an interesting and extremely special pattern of 'old on the sides and young in the center' . The younger results in the center means the middle segment of Nujiang River got through relative quicker thermal histories. The youngest and special region lies in the three rivers parallel flowing area and water vapor channel of southwest monsoon, resulting in the significantly difference in precipitation patterns between the different segments. We therefore conclude that climate led to its rapid landscape evolution and then caused the youngest samples exposed in the middle segment of Nujiang River. All the AFT age peaks can be divided into five groups; 5.3-4.4 Ma, 7.7-7.3 Ma, 12. 8 ~ 10. 7 Ma, 26. 8 -22. 2 Ma and 48. 7 ~ 30. 1 Ma, documenting the main stages of Cenozoic thermal histories in Nujiang River Basin, western Yunnan. Furthermore, the prominent characters of the detrital river sand are identified, as an indication of segmentation to get more accurate thermal information.%河流搬运沉积的河砂作为流域内地质体的平均产物,可以有效地揭示整个流域内区域性的地质体热史演化.对同一河流进行分段采样能够揭示更为详实的热史演化差异.本文对滇西境内怒江上游至下游采集了7个河砂样品进行磷灰石裂变径迹定年,主要年龄峰值依次为:12.2 Ma和12.8 Ma,7.7 Ma,5.3 Ma、4.4 Ma和4.9 Ma,7.3 Ma;总体上呈现

  18. 信息动态%Zircon Fission-Track Thermochronology (ZFT): Advances and Applications

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The Fission-track technique is a unique low-temperature thermochronology for assessment of timetemperature dependent evolution in various geological settings. Because of a higher closure temperature and partial annealing zone than apatite fission-track, zircon fission-track has a featured geological significance and application.Since the last decade of the 20th century, there has been a great number annealing research performed on zircon fission-track, including annealing properties, track measurement, annealing models, and annealing knowledge from samples of outcrops and boreholes. An investigation of zircon fission track has been made firstly in general covering various analytical procedures, measurement standards, experiment annealing models, coupled with a comparison between closure temperature and partial annealing zone obtained from different methods. Some major applications of zircon fission-track are summarized then, concerning analysis of sediment provenance and thermal history of the basin, cooling and exhumation of the orogen, and faulting thermal adjustment. It is pointed out that the combination of fission-track and (U-Th)/He is the future research trend.

  19. Age and Thermal History of the East Ore Section,Bayan,Obo Deposit—A Fission Track Study

    Institute of Scientific and Technical Information of China (English)

    张峰; 刘铁庚; 等

    1997-01-01

    Considerable attention has been paid in recent years to the study of geothermal history by using spontaneous fission tracks of 238U recorded in minerals.Apatite and zircon were used for fission track study in this paper because apatitie has been widely used as a natural geothermometer(Wang Shicheng et al., 1994) to reveal the thermal evolution of sedimentary rocks based on its low annealing temperature of fission tracks and zircon is characterized by a closing temperature above 700℃,The samples were collected from ferruginous,siliceous slate wall rock at the upper levels of the orebody and Nb-REE-Fe ores from deep tunnels.The age and thermal evolution of the orebody were discussed in terms of fission track characters and their length variations observed in the coexisting apatite and zircon in the same specimen.

  20. 孔雀河斜坡与库鲁克塔格隆起构造事件的裂变径迹证据%Detrital zircon and apatite fission track study of key tectonic events of Kongquehe slope and Kuruketage uplift, north-eastern Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)

    肖晖; 任战利; 王起琮; 赵靖舟

    2011-01-01

    文章以塔里木盆地东北缘库鲁克塔格隆起与孔雀河斜坡盆山系统为主要研究对象,在该地区露头和钻井样品开展碎屑磷灰石、锆石裂变径迹研究,对库鲁克塔格构造演化中关键构造事件提供热年代学约束.锫石样品在加里东晚期-早海西期达到最大古地温,之后经历了长期的抬升降温过程,锆石最小峰值年龄记录了371~392 Ma 和328~305.7 Ma二次构造抬升年龄;在晚侏罗-晚白垩世,样品逐渐退出磷灰石部分退火带底界,磷灰石裂变径迹记录了134.5~164 Ma、73~100 Ma和35.4 Ma三次构造抬升事件年龄,其中73~100 Ma为主要构造抬升年龄.海西期构造事件年龄反映了孔雀河斜坡由沉降转入剥蚀演化阶段,对油气藏的形成具有重要意义;晚白垩世构造事件则反映了库鲁克塔格山的强烈隆升.%This paper focuses on the study of basin-and-range relations about Kongquehe slope and Kuruketage uplift. Thermochronology constraints were made to the key tectonic events in the Kuruketage tectonic evolution history, using the methods of detrital zircon and apatite fission track, sampled from outcrop area and well cores. The time of the maximum palaeotemperature from zircon samples was determined during late-Caledonian to early-Hercynian cycle, and from then on, the samples experienced the procedure of tectonic uplifts and temperature drop times.Two thermochronology ages of zircon fission track were recorded, which reflect two tectonic events happened in 371~392 Ma and 328~305.7 Ma. Three later tectonic uplifting events were recorded by apatite fission track, whose thermochronology ages are 134.5~164 Ma, 73~100 Ma and 35.4 Ma respectively, after the palaeotemperature of samples was decreased out of the partial annealing zone's base level. The Hercynian ages from the zircon samples indicate the tectonic transformation from subsidence to uplift in the Kongquehe slope, which is significant to oil

  1. 伊犁盆地南缘沉积构造演化与砂岩型铀矿化的关系--来自磷灰石裂变径迹的证据%The Coupling Relationship Between Sandstone Type Uranium Mineralization and Sedimentary tectonic Evolution in the South Margin of Yili Basin---Evidence from Apatite Fission Track

    Institute of Scientific and Technical Information of China (English)

    潘澄雨; 刘红旭; 陈正乐; 张晓; 王永文; 孟云飞; 丁波

    2015-01-01

    Study of mountain basin coupling is an important part of continental dynamics research.This paper mainly presented the analyses results of apatite fission track both from western Tianshan range and the Yili basin to reveal the up roofing history of the western Tianshan and to explore the control effect of mountain basin coupling to mineralization.25 samples, including granite, volcanics, sandstones from middle western Tianshan,Chabuchaer mountain and the drilling wells in southern part of the Yili basin were collected,and apatite was selected for fission track dating in the lab.Temperature time modeling of apatite was also completed based on data measurements of fission track length and age.Analyses results revealed that the western Tianshan has probably experienced four phases of rapid cooling events during the Mesozoic to Cenozoic, i.e.from Late Triassic to Early Jurassic (220 ~180Ma),Middle Jurassic (1 70 ~ 140Ma ), Middle Cretaceous (1 10 ~ 80Ma ), and Late Cenozoic (since 24 Ma).Combined with regional data analysis,basin sedimentary tectonic evolution process, and basin sandstone type uranium mineralization stage research,samples test results in basin drilling revealed that sedimentary tectonic evolution and sandstone type uranium mineralization of Yili basin have good coupling relationship with tectonic uplift and denudation processes of western Tianshan.%盆山耦合研究是大陆动力学研究的一个重要组成部分。笔者主要通过磷灰石裂变径迹测年结果来限定西天山山脉的隆升剥露过程,探讨盆山耦合及其对成矿的控制作用。野外样品系统采集于西天山山脉及伊犁盆地南缘钻孔中,选磷灰石开展了裂变径迹测试分析,并开展了磷灰石的温度时间反演模拟研究。结果表明,西天山至少存在4个阶段的构造隆升剥露事件,时间上分别为:三叠纪末侏罗纪早期(220~180Ma)、侏罗纪中期(170~140Ma),白垩纪中期(110~80Ma)和新生代期间(24

  2. Apatite Fission Track Constraints on the Mesozoic Tectonic Activities in Shangdan Depression,Yin’e Basin,Inner Mongolia%内蒙古银额盆地尚丹凹陷中生代构造活动的磷灰石裂变径迹约束

    Institute of Scientific and Technical Information of China (English)

    韩伟; 卢进才; 魏建设; 张云鹏; 李玉宏; 李岩

    2015-01-01

    本文通过对银额盆地东南缘尚丹凹陷的三条剖面开展磷灰石裂变径迹研究,揭示了研究区中生代构造演化史。5个样品的中心年龄为129±10~159±11 Ma,径迹长度在12.5±2.0~13.3±1.7μm 之间,各样品径迹长度分布具有范围较宽、单峰的特征。反映了在晚侏罗世—早白垩世时期,受燕山Ⅲ幕构造运动影响,研究区遭受抬升、剥蚀的构造事件。该时期抬升速率约为40~55 m/Ma,且由北向南逐渐降低,是研究区主要抬升期,油气系统遭受破坏。此后至白垩纪末,研究区阿木山组始终处于生烃门限温度内,且构造背景稳定,有利于油气生成。结合与北部凹陷带所开展工作(磷灰石裂变径迹记录年龄为90~113 Ma),证明银额盆地中生代时期存在差异隆升,不同构造位置受不同期次构造运动的影响也存在差异,为银额盆地构造演化研究提供了依据。%Using to the apatite fission track of the three sections in the Shangdan depression,the southeastern margin of the Yin’e basin,the Mesozoic tectonic evolution history in the study area has been studied.The fission track ages of 5 samples range from 129 ±10 Ma to 159 ±1 1 Ma,and the track length range from 12.5±2.0 μm to 13.3±1.7μm.The track length in these samples is characterized by a wide range,and a unimodal pattern.The results show that the study area has undergone uplift-erosion events in the Late Jurassic-Early Cretaceous,which have been affected greatly by curtain Ⅲ of the Yanshan movement. Specifically,the depression has experienced a uplifting process at a uplift rate of 40 ~ 55m/Ma with decreasing from north to south.It was the major uplifting period of the study area,and the petroleum system was eventually damaged.Since then,to late Cretaceous the Amushan Formation in the study area came into hydrocarbon threshold,which made great contributions to hydrocarbon generation.Combined with the work undertaken in the northern depression

  3. Projected length annealing of etched {sup 152}Sm ion tracks in apatite

    Energy Technology Data Exchange (ETDEWEB)

    Alencar, I., E-mail: igorav@ifi.unicamp.br [Departamento de Raios Cosmicos e Cronologia, Instituto de Fisica ' Gleb Wataghin' , UNICAMP, Rua Sergio Buarque de Holanda 777, CEP 13083-859 Campinas-SP (Brazil); Guedes, S. [Departamento de Raios Cosmicos e Cronologia, Instituto de Fisica ' Gleb Wataghin' , UNICAMP, Rua Sergio Buarque de Holanda 777, CEP 13083-859 Campinas-SP (Brazil); Jonckheere, R. [Geologisches Institut, Technische Universitaet Bergakademie Freiberg, Bernhard-von-Cotta-Strasse 2, Freiberg (Sachsen) 09599 (Germany); Trautmann, C. [Gesselschaft fuer Schwerionenforschung, GSI, Planckstrasse 1, Darmstadt 64291 (Germany); Soares, C.J.; Moreira, P.A.F.P. [Departamento de Raios Cosmicos e Cronologia, Instituto de Fisica ' Gleb Wataghin' , UNICAMP, Rua Sergio Buarque de Holanda 777, CEP 13083-859 Campinas-SP (Brazil); Curvo, E.A.C. [Instituto de Fisica, UFMT, Av. Fernando Correa da Costa, S/N, CEP 78060-900 Cuiaba-MT (Brazil); Tello, C.A.; Nakasuga, W.M. [Departamento de Fisica, Quimica e Biologia, Faculdade de Ciencia e Tecnologia, UNESP, Rua Roberto Simonsen 305, CEP 19060-900 Presidente Prudente-SP (Brazil); and others

    2012-10-01

    Slices of apatite (cut {approx}45 Degree-Sign apart from c-axis) were irradiated with {sup 152}Sm ions and heated at different steps in order to investigate the thermal annealing property of tracks generated by these ions. The ions were impinged with 45 Degree-Sign and {approx}150 MeV at apatite surface. Samples were etched with diluted nitric acid. Results of annealed projected lengths are presented for isochronal 10, 100 and 1000 h thermal treatments (runs) for samples with and without pre-annealing preparation. For low annealing temperatures, a distinct behavior of these samples was observed: pre-annealed samples presented a faster annealing rate. At elevated temperatures, the behavior seems to be equal. A single activation energy model was fitted to data and the energy obtained is in agreement with literature. Finally, despite the different trend in comparison with annealing rates of confined fission tracks, extrapolation to geological timescales presents reasonable estimates, indicating small influence of surface effects and, in principle, the possibility to employ ion tracks as proxies for annealing kinetics.

  4. Thermal history from Pocos de Caldas alkaline massif, SP/MG , Brazil and dyke rich margins using apatite fission track analysis; Historia termica do macico alcalino de Pocos de Caldas (SP/MG) e adjacencias atraves da analise de datacao por tracos de fissao em apatitas

    Energy Technology Data Exchange (ETDEWEB)

    Franco, Ana Olivia Barufi; Godoy, Daniel Francoso de [UNESP, Rio Claro, SP (Brazil). Pos-Graduacao em Geociencias. Dept. de Petrologia e Metalogenia]. E-mail: aobf@rc.unesp.br; Hackspacher, Peter Christian; Ribeiro, Luis Felipe Brandini [UNESP, Rio Claro, SP (Brazil). Dept. de Petrologia e Metalogenia; Guedes, Sandro [Universidade Estadual de Campinas, SP (Brazil). Instituto de Fisica Gleb Wataghin

    2005-09-15

    The South American Platform in southeastern Brazil records a long history of tectonic magmatic and uplift events, which resulted from the opening of the South Atlantic Ocean, Cretaceous reactivation and epirogeneic processes. Specific manifestations include the basic magmatism of the Serra Geral Formation of the Parana Basin and alkaline magmatism of Pocos de Caldas - Cabo Frio Lineament, as well as the uplift of the Serra da Mantiqueira and Serra do Mar mountain ranges. Thermo tectonic and geochronological studies using the K-Ar method and apatite fission track analysis in samples of the Pocos de Caldas alkaline massif show an initial evolution beginning 89 Ma related to a tectonic uplift, interpreted as related to the intrusion's doming. This was followed by an important episode of rapid cooling related to the formation of the massif. At the same time, the mountains that surround the massif record heating events in response to the alkaline intrusion, between 70 and 50 Ma. Periods of slow uplift, probably related to the South American Erosion Cycle (between 50 and 30 Ma) and Velhas Erosion Cycle (from 25 Ma), indicate a strong manifestation of denudation in this area. (author)

  5. 滇西石鼓杂岩南部早白垩世以来剥露隆升的锆石和磷灰石裂变径迹证据%The exhumation and uplift of the southern Shigu complex since Early Cretaceous evidenced by zircon and apatite fission track

    Institute of Scientific and Technical Information of China (English)

    陈小宇; 刘俊来; 吴文斌

    2016-01-01

    石鼓杂岩位于青藏高原东南缘经历了多期变质变形作用叠加。为了揭示杂岩体的低温热演化与浅部剥露历史,采集了石鼓杂岩南段石鼓镇-拉巴支村剖面变质岩中的锆石和磷灰石,开展裂变径迹分析。结果表明,石鼓杂岩从早白垩世(133~145Ma)到渐新世(31Ma)经历了一次缓慢的剥露(1.08℃/Ma),而从渐新世开始,其南部经历了较快速的剥露过程(3.23℃/Ma)。磷灰石热史模拟也反映出第二阶段较为快速的冷却过程。结合区域构造分析认为,拉萨与羌塘板块碰撞的远程效应影响早白垩世以来藏东地区地壳结构的调整,导致石鼓杂岩南部出现了第一阶段的剥露作用;而印度与欧亚板块碰撞与后碰撞过程对于石鼓杂岩的新生代剥露具有重要影响。%The Shigu complex lies on the southeastern margin of the Tibetan Plateau, and is mainly distributed in Shigu and Zhongdi⁃an areas. The complex has experienced polyphase superposition of metamorphism and deformation. In order to reveal the low tem⁃perature thermal evolution and exhumation history at the shallow crustal level of the complex and correctly understand the exhuma⁃tion and tectonic evolution of the metamorphic dome in eastern Tibet, the authors collected zircon and apatite fission track samples for the fission track analysis along the Shigu Town-Labazhi section. The analytical results show that the Shigu complex firstly experi⁃enced a slow cooling and exhumation from Early Cretaceous (133~145Ma) to Oligocene (31Ma), and a relatively rapid cooling pro⁃cess started from Oligocene. Time-temperature history simulated by inverse modeling of apatite fission track also reflects a relatively rapid cooling process at the second stage. From regional structural analysis, it is suggested that the far-field effects of the collision be⁃tween the Lhasa and Qiangtang plates may have strongly affected the Early Cretaceous

  6. Absolute measurements of the uranium concentration in thick samples using fission-track detectors

    Science.gov (United States)

    Enkelmann, Eva; Jonckheere, Raymond; Ratschbacher, Lothar

    2005-04-01

    We propose an improved equation for calculating the uranium concentration in thick samples based on induced fission-track counts in an external detector that takes into consideration (1) the fission-fragment ranges in the sample and external detector, (2) the etchable track length and (3) the track counting efficiency in the external detector. The values of these parameters have been determined by calculation and experiment and are shown to have a significant effect on the calculated uranium concentrations. The new equation was tested by calculating the uranium concentrations in standard uranium glasses (CN-5; IRMM-540R) and apatite samples (Durango; horse tooth) in which the uranium content was also determined with independent methods (INAA; ENAA; TIMS). The results show that: (1) accurate measurements with the fission-track method are feasible within a broad range of uranium concentrations and (2) uranium determinations based on standards are only accurate if the standard and sample are made of the same material. Because the absolute fission-tack dating method is also based on accurate thermal neutron fluence measurements and similar correction factors for the track registration and counting efficiencies, this study provides a strong endorsement for the fact that absolute fission-track ages are accurate.

  7. 磷灰石裂变径迹研究新疆阿尔泰山南缘剥露历史及古地形再造%Apatite Fission Track Analyses of Exhumation History and Antiquated Topography Reconstruction in the Southern Margin of Altai, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    宋高; 袁万明; 赵文菊; 刘海涛

    2013-01-01

    Thirteen apatite samples from the Altai region were employed to reveal the history of uplifting and exhumation using fission track method and to reconstruct antiquated topography.History of cooling evolution is characterized with a model of three stages.Stage one from 120 Ma to 80 Ma or 70 Ma records the highest temperature and is in the bottom temperature of apatite fission track anneal strip,with THE dominant temperature of higher than 100℃.During late Late Cretaceous and early Paleogene periods,the Altai region had no distinct tectonic activity but just weak lifting and exhumation.Stage two lasting from 80~70 Ma to 20 Ma records rapid cooling with temperature decreasing from 120~100℃ to 35~30℃.Since mid-Palegene,especially from mid-late Miocene,Himalayan movement resulted in strong uplift and exhumation,with mountains uplifting and basins relatively lowering.The final stage from 30 Ma to 20 Ma and to present records slow cooling process,with temperature going down from 35 ~ 30℃ to the temperature of current Earth's surface (an average temperature of 20℃).The uplift rates of three stages are 0.025 mm/a,0.027 mm/a and 0.02 mm/a,respectively,while uplift magnitude of the three are correspondingly 1.14 km,1.34 km and 0.43 km.The surface uplift ranges between 634 and 2394 m.Average values for exhumation and uplift are 2168 m and 3318 m,and the balance of them (1150 m) is the average height of the mountain today.%本文应用裂变径迹技术对阿尔泰地区13个磷灰石裂变径迹样品进行分析研究,揭示了该地区的隆升剥露历史,并进行了古地形再造.热历史演化模式具有3个阶段的特征:①约120~80 Ma至70 Ma,温度较高,处于磷灰石裂变径迹退火带底部温度,主体高于100℃,晚白垩世末期和早第三纪初期,阿尔泰地区构造运动不明显,仅有微弱的升降运动,均夷作用显著;②从80~70 Ma至30~20 Ma,快速冷却,温度由85~75℃降至35~30℃,晚第三纪,自中新

  8. 库鲁克塔格南部山前带中-新生代构造演化史--来自磷灰石裂变径迹的证据%Meso-Cenozoic Tectonic Evolution History in the Southern Piedmont Zone of Kuruktag---the Evidence Taken from Apatite Fission Track

    Institute of Scientific and Technical Information of China (English)

    刘阵; 张洪美; 何金有; 何登发; 温佳霖; 马渭; 王永飞

    2016-01-01

    Based on analysis of apatite fission track data and thermal history modeling, and combined with field geological survey, the Meso—Cenozoic tectonic evolution history in the southern piedmont zone of Kuruktag has been studied. Results showed that the formation had the characteristics of keeping the Kelatong attitude from Kuruktag uplift to the southern pied-mont direction. The age of apatite in the southern piedmont zone of Kuruktag recorded the two tectonic cooling events in 182Ma and 167—142 Ma, and the simulation of fission track thermal history indicated that Hercynian tectonic uplifted, Early—Middle Jurassic formation descended, Late Jurassic—Early Cretaceous tectonic uplifted, and Late Cenozoic tectonic uplifted, etc. Comprehensive study showed that the southern piedmont zone had been affected commonly by the early tec-tonic uplift that created in Hercynian and Yanshan movement, the Himalaya movement mainly caused the strong thrust at the upper part of fault. From the viewpoint of deposition, the deposition center of early—middle Jurassic is located in the ancient position of Queerqueke mountain.%通过对磷灰石裂变径迹数据的分析和热史模拟,结合野外地质调查,研究了库鲁克塔格南部山前带中—新生代构造演化史。结果显示,从库鲁克塔格隆起到南部山前带方向,地层具有稳定克拉通地层产状的特征。库鲁克塔格南部山前带磷灰石年龄记录了182Ma和167—142Ma两期构造冷却事件,裂变径迹热史模拟反映出海西期构造抬升、早—中侏罗世埋藏沉降、晚侏罗世—白垩纪初构造抬升和新生代晚期构造抬升等演化阶段。综合研究表明,南部山前带普遍受到海西期和燕山运动早期构造抬升的影响,喜马拉雅运动主要造成了研究区断裂上盘的强烈逆冲推覆;早—中侏罗世埋藏沉降阶段,从沉积角度看,沉积中心位于却尔却克山所在的古位置。

  9. High temperature annealing of fission tracks in fluorapatite, Santa Fe Springs oil field, Los Angeles Basin, California

    Science.gov (United States)

    Naeser, Nancy D.; Crowley, Kevin D.; McCulloh, Thane H.; Reaves, Chris M.; ,

    1990-01-01

    Annealing of fission tracks is a kinetic process dependent primarily on temperature and to a laser extent on time. Several kinetic models of apatite annealing have been proposed. The predictive capabilities of these models for long-term geologic annealing have been limited to qualitative or semiquantitative at best, because of uncertainties associated with (1) the extrapolation of laboratory observations to geologic conditions, (2) the thermal histories of field samples, and (3) to some extent, the effect of apatite composition on reported annealing temperatures. Thermal history in the Santa Fe Springs oil field, Los Angeles Basin, California, is constrained by an exceptionally well known burial history and present-day temperature gradient. Sediment burial histories are continuous and tightly constrained from about 9 Ma to present, with an important tie at 3.4 Ma. No surface erosion and virtually no uplift were recorded during or since deposition of these sediments, so the burial history is simple and uniquely defined. Temperature gradient (???40??C km-1) is well established from oil-field operations. Fission-track data from the Santa Fe Springs area should thus provide one critical field test of kinetic annealing models for apatite. Fission-track analysis has been performed on apatites from sandstones of Pliocene to Miocene age from a deep drill hole at Santa Fe Springs. Apatite composition, determined by electron microprobe, is fluorapatite [average composition (F1.78Cl0.01OH0.21)] with very low chlorine content [less than Durango apatite; sample means range from 0.0 to 0.04 Cl atoms, calculated on the basis of 26(O, F, Cl, OH)], suggesting that the apatite is not unusually resistant to annealing. Fission tracks are preserved in these apatites at exceptionally high present-day temperatures. Track loss is not complete until temperatures reach the extreme of 167-178??C (at 3795-4090 m depth). The temperature-time annealing relationships indicated by the new data

  10. Emplacement time of the Loe-Shilman carbonatite from NW Pakistan: Constraints from fission-track dating

    Energy Technology Data Exchange (ETDEWEB)

    Khattak, N.U. [National Centre of Excellence in Geology, University of Peshawar (Pakistan)], E-mail: nimat_khattak@yahoo.com; Akram, M. [Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); Khan, M.A. [National Centre of Excellence in Geology, University of Peshawar (Pakistan); Khan, H.A. [COMSATS Headquarters, 4th Floor, Shahrah-e-Jamhuriat, G-5/2 Islamabad 44000 (Pakistan)

    2008-08-15

    The Loe-Shilman carbonatite complex is situated in the extreme west of the Peshawar Plain Alkaline Igneous Province (PAIP), near the Pakistan-Afghanistan border. It comprises sill-form bodies emplaced along an E-W trending and N dipping fault zone in Paleozoic to Precambrian metasedimentary rocks of Khyber Agency. Fission-track dating studies on the apatite crystals using the external detector method and age standard approach (the {zeta} method) yielded an age of 30.0{+-}1.5Ma for the Loe-Shilman carbonatite. Close agreement between the previously determined radiometric ages from the same as well as the neighboring carbonatite complexes of the PAIP and the fission-track apatite age of this study indicates that the Loe-Shilman carbonatite was emplaced at relatively shallow crustal level and quickly cooled to low temperatures (<60{sup 0}C) required for the complete retention of fission tracks in apatite and that the fission-track age of this study is the emplacement age of the Loe-Shilman carbonatite.

  11. Cenozoic Uplift and Denudation of the EW-trending Range of Northern Altun Mountains:Evidence from Apatite Fission Track Data%阿尔金北缘EW向山脉新生代隆升剥露的裂变径迹证据

    Institute of Scientific and Technical Information of China (English)

    孙岳; 陈正乐; 陈柏林; 韩凤彬; 周永贵; 郝瑞祥; 李松彬

    2014-01-01

    This paper mainly presents analytical results of apatite fission-track ages to constrain the uplifting characteristics of EW-trending range of Northern Altun Mountains. 22 rock mass samples were collected from Zhuoerbulake, Dapinggou, and Kaladawan in EW-trending mountain range of Northern Altun Mountains. Fission-track ages for these samples range from (62.6±3.5) to (28.3±1.7) Ma with mean track lengths varying from (13.25±0.15) to (14.29±0.1)μm. According to track lengths and measured age data, the authors carried out the inversion simulation on temperature and age of apatite. The results show a specific regularity of the uplifting of Northern Altun Mountains. In the SN direction, the fission-track ages display a uplifting trend from south to north. In the EW direction, the ages of Dapinggou area in the middle mountains were older than those of other areas and confined to Paleocene and Eocene, and imply an uplifting trend from the middle outwards. The similar thermal history simulation lines of all samples and the single peak of track lengths are considered to have been caused by rapid uplifting during the Paleocene-Eocene (63~28 Ma) and steadiness during the Miocene and later periods in the Northern Altun Mountains. A comparative study of the uplifting and exhumation of the whole Altun area shows that the mountains uplifting and denudation of this region had both global and unique features in Cenozoic: the uplifting of the Altun Mountains had universality and regional features in Paleogene, but uplifting and exhumation existed in NEE-trending and NE-trending mountain ranges in Miocene and subsequent period. It is held that the rapid strike-slip Altun fault has had no influence on uplifting and denudation of EW-trending mountain ranges in Northern Altun Mountains since Miocene.%本文主要利用磷灰石裂变径迹测年技术探讨了阿尔金北缘EW向山脉隆升的时空差异特征。22个岩体分别采自阿尔金北缘EW向山体中的卓尔布

  12. Fission track evidence on thermal history of Jiama polymetallic ore district, Tibet

    Institute of Scientific and Technical Information of China (English)

    袁万明; 侯增谦; 李胜荣; 王世成

    2001-01-01

    It is a new attempt to study thermal evolution related to mineralization using the fission track (FT) method. Apatite and zircon fission track data are reported for 6 samples collected from Jiama ore district as well as its periphery. The FT ages of apatites in the ore district are (16.1±0.9) Ma and (18.8±1.1) Ma and reflect the age of late period of hydrothermal mineralizing event. Apatite FT age of (22.0±4.3) Ma and zircon FT age of (20.9±2.0) Ma are related to the early period of mineralization. Another zircon FT age of (341.6±79.1) Ma, inheriting mineral source characteristic, has no connection with the mineralization. Based on the thermal history analysis, the mineralization began before 25-22 Ma. Cooling rate in the ore district is 5-6℃/Ma averagely, in which a slow cooling occurred at 90-80℃. About 2.7 km has been denuded and the denudation rate is higher than the uplifting rate.

  13. Apatite Fission Track Study of the Cretaceous-Cenozoic Stepwise Uplift of the Middle Segment of the Qilian Mountain%祁连山中段白垩纪以来阶段性构造抬升过程的磷灰石裂变径迹证据

    Institute of Scientific and Technical Information of China (English)

    戚帮申; 胡道功; 杨肖肖; 张耀玲; 谭成轩; 张鹏; 丰成君

    2016-01-01

    The Qilian Mountain constitutes the northeastern margin of the Tibetan Plateau, and hence characteristics of its tectonic activity recorded by apatite fission track (AFT) analysis play an important role in understanding the uplift and growth of the Tibetan Plateau. 22 samples collected for AFT analysis from the Qilian Mountain belt were located along NS-trending transect across southern Qilian fold belt, Shule Nanshan-Laji Shan suture zone, Central Qilian massif and North Qilian suture zone. AFT ages range from (13±2) Ma to (124±11) Ma, and mean track lengths range from (10.3±1.8)μm to (13.6±2.3)μm. Samples from the same tectonic unit have positive correlation between AFT ages and elevations, whereas samples with younger ages ((60±5) Ma to (13±2) Ma) are clustered around North Central Qilian fault. On the basis of the measured apatite fission track age data, the inversion simulation was used to analyze the thermal history of the Qilian Mountain. The best-fit line of the time-temperature modeling results suggest that at least three cooling periods have occurred since early Cretaceous: 1) Rapid cooling in the Qilian Mountain during early Cretaceous (>(129±14) Ma to (115±17) Ma). The cooling rates and exhumation rates of South Qilian fold belt and Shule Nanshan -Laji Shan suture zone were great, suggesting that the Qilian Mountain formed the northeastern margin of the Tibetan Plateau during early Cretaceous; 2) From middle Cretaceous to Miocene ((115±17) Ma to (25±7) Ma), the cooling rates and exhumation rates of South Qilian fold belt and Shule Nanshan-Laji Shan suture zone were quite low, implying that the tectonic activity of the Qilian Mountain was weak during middle Cretaceous to Miocene; 3) Since Miocene time, timing of both thrust activities and regional rapid cooling event shows that the Qilian Mountain experienced north-eastward rise and growth, which is in line with the hypothesis that the Qilian Mountain was formed by thrusting within the

  14. Unroofing history of a suture zone in the Himalaya of Pakistan by means of fission-track annealing ages

    Science.gov (United States)

    Zeitler, P.K.; Tahirkheli, R.A.K.; Naeser, C.W.; Johnson, N.M.

    1982-01-01

    The uplift history of the Swat Valley and Hazara region of northwestern Pakistan has been established using 22 fission-track dates on apatite, zircon and sphene. A major fault, the Main Mantle Thrust (MMT) strikes east-west across the Swat Valley, separates regions of markedly differing fission-track age regimesm, and may be a suture zone separating an extinct island arc terrane on the north from the Indian plate to the south. Fission-track ages ranging from about 55 to 58 m.y. for sphene, 18 to 53 m.y. for zircon, and 9 to 17 m.y. for apatite were obtained from the region north of the MMT. To the south the fission-track age ranges are 20 to 25 m.y. for sphene, 17 to 26 m.y. for zircon, and 16 to 23 m.y. for apatite. Disparate zircon and sphene ages on each side of the MMT imply different cooling histories for each side of the fault prior to 15 m.y. Similar apatite ages on both sides of the fault imply similar cooling histories during the past 15 m.y. This may indicate that faulting ceased by 15 m.y. Mean uplift rates have been derived from the fission-track data using mainly the mineral-pair method. Uplift rates in the region north of the MMT increased from 0.07 to 0.20 mm/yr during the period 55 to 15 m.y. South of the fault, uplift rates averaged in excess of 0.70 mm/yr for the period 25 to 15 m.y. During the past 15 m.y. uplift across the MMT in the Swat Valley showsno discontinuities, ranging from 0.16 mm/yr in the south to 0.39 mm/yr in the north. A plausible interpretation for the fission-track uplift data has the MMT verging to the south with overthrusting taking place at a depth between 3.5 and 6.0 km, juxtaposing two terranes that were originally separated by a substantial, but unknown distance. In this model, regional uplift followed cessation of faulting just prior to 15 m.y. ?? 1982.

  15. Thermal history of rocks in southern San Joaquin Valley, California: evidence from fission-track analysis

    Science.gov (United States)

    Naeser, N.D.; Naeser, C.W.; McCulloh, T.H.

    1990-01-01

    Fission-track analysis has been used to study the thermal and depositional history of the subsurface Tertiary sedimentary rocks on both sides of the active White Wolf reverse fault in the southern San Joaquin Valley. The distinctly different thermal histories of the rocks in the two structural blocks are clearly reflected in the apatite fission-track data, which suggest that rocks in the rapidly subsiding basin northwest of the fault have been near their present temperature for only about 1 m.y. compared with about 10 m.y. for rocks southeast of the fault. These estimates of heating time agree with previous estimates for these rocks. Zircon fission-track data indicate that the Tertiary sediments were derived from parent rocks of more than one age. However, from at least the Eocene to late Miocene or Pliocene, the major sediment source was rocks related to the youngest Sierra Nevada Mesozoic intrusive complexes, which are presently exposed east and south of the southern San Joaquin Valley. -from Authors

  16. 西藏羌塘盆地白垩纪中期构造事件的磷灰石裂变径迹证据%Apatite fission track thermochronology evidence for the Mid-Cretaceous tectonic event in the Qiangtang Basin, Tibet

    Institute of Scientific and Technical Information of China (English)

    王立成; 魏玉帅

    2013-01-01

    拉萨与羌塘地块于白垩纪中期的碰撞造山对羌塘原型盆地的热体制和构造演化有着重要影响.运用磷灰石裂变径迹方法,对羌塘盆地隆鄂尼夏里组和托纳木雪山组砂岩分析表明,裂变径迹年龄集中在120~ 80Ma之间,表明在白垩纪中期,羌塘盆地普遍发生了一次构造抬升事件,该期构造事件的年龄与盆地内早白垩世的岩浆热事件、主要构造变形作用发生在晚白垩世以及雪山组和阿布山组角度不整合的时代(125~75Ma)较一致,是拉萨与羌塘地块碰撞造山事件的记录.热历史模拟表明,白垩纪中期构造事件对羌塘盆地南部和北部的热演化历史有着差异影响,羌塘盆地南部降温速率相对不大,抬升剥蚀厚度约1500m,而北部古地温迅速降温到近地表温度,抬升剥蚀厚度近4000m.这种差异抬升剥蚀可能与班公湖-怒江洋壳向南俯冲使得因拉萨地块构造负载而导致羌塘地块的挠曲有关.%Collision and orogenesis between Lhasa and Qiangtang terrane in Early-Middle Cretaceous have significant impact on the thermal regime and tectonic evolution of the proto-Qiangtang Basin. Apatite fission track dating was applied to analyze the sandstone samples of the Xiali Formation from Longe' ni area in southern Qiangtang Basin and of the Xueshan Formation from Tuonamu area in northern Qiangtang Basin. The results show single population grain ages with a single mean age and associated central ages mainly ranging from 120Ma to 80Ma and indicate that there would be a tectonic event in middle Cretaceous. The ages coincide well with the ages of magmatism in the Early Cretaceous, main deformation occurred in the Late Cretaceous, and angular unconformity indicated by the Xueshan and Abushan formations. Therefore, the Mid-Cretaceous tectonic event is the result of collision between Lhasa and Qiangtang terrane. Thermal history modeling suggests a different thermal evolution of southern and

  17. Analysis of Basin-Mountain Evolution History in Northern Margin of Yilianhabierga Mountain by Using Apatite Fission-Track%运用磷灰石裂变径迹分析依连哈比尔尕山北缘盆山演化史

    Institute of Scientific and Technical Information of China (English)

    潘澄雨; 孟元库; 汪新文

    2012-01-01

    通过对准噶尔盆地磷灰石裂变径迹样品的表观年龄和封闭径迹长度分布特征的分析与正演模拟,定性、半定量地研究了该区相关岩石组合的地热演化史。研究结果表明,依连哈比尔尕山北缘主要经历了3个隆升-剥露阶段:第一阶段为晚侏罗世晚期-早白垩世初,剥蚀量在头屯河地区最大,为1.5-2.0km,柴窝堡南缘约1.0km,托斯台南缘约1.0km;第二阶段为晚白垩世-古近纪初,剥蚀量西大东小,托斯台南缘为1.5~2.0km,头屯河地区为1~1.5km,柴窝堡南缘为0.8~1.0km;第三阶段为渐新世末以来的大幅度隆升、剥露阶段,剥蚀量西大东小,托斯台南缘为4.0~5.0km,头屯河地区约3.0km,柴窝堡南缘为2.0—2.5km.%By analyzing the apatite fission track data and forward modeling, the thermal history of relevant rock assemblage is studied quali- tatively to semi-quantitatively in Junggar basin. The result shows that three uplifting-exhumating stages appeared in northern Yilianhabier- ga mountain: ① From the late stage of Late Jurassic to the early stage of Early Cretaceous, with denuded thiekness in Toutunhe of 1.5-2.0 km, in the south edge of Chaiwopu of about 1.0 km, and in the south edge of Tuositai of about 1.0 km; ② from the Late Cretaceous to the Early Paleogene, with denuded thickness reducing from the west to the east, in the south edge of Tuositai of 1.5-2.0 km, in Toutunhe of 1- 1.5 km, and in the south edge of Chaiwopu of 0.8-1.0 km; ③ since the end of Oligocene, being large uplifting and exhumation stage, with denuded thickness reducing from the west to the east, in the south edge of Tuositai of 4.0-5.0 km, in Toutunhe of about 3.0 km, and in the south edge of Chaiwopu of 2.0-2.5 km.

  18. 从裂变径迹分析新疆阿尔泰南部地区构造活动与古地形的变化%Apatite Fission Track Analysis on Tectonic Activities and Paleotopography in Southern Altai Region,Xinjiang,China

    Institute of Scientific and Technical Information of China (English)

    赵文菊; 袁万明; 刘海涛; 宋高

    2013-01-01

    This work engages apatite fission track evidences on thermotectonic history , rock uplift rate ,denudation extent in southeastern Altai region .Fission track ages of 14 samples range from (59.4 ± 5.8) Ma to (109.7 ± 8.1) Ma and the length is between (12.0 ± 2.5)μm and (13.7 ± 1.5)μm .Thermal modeling reveals that the samples have a three-stage of uplift-cooling history .The first stage is in an overall initial uplift before 108 Ma ,the second stage from 108 Ma to 28 Ma experiences a slow cooling phase ,and the last stage through a rapid-cooling process since 28 Ma with a cooling rate 1.25-1.61 ℃ /Ma and denudation amount 1.17-1.50 km ,the fast exhumation period in the area .The sample ages could be divided into 4 age groups ,reflecting multiple tectonic events with different uplift rates .The paleotopography altitude changes from 3 895 m to 821 m ,2 250 m to 762 m etc .,and the amplitude of changes reaches to 3 300-1 400 m since 90 Ma .The phenomenon of Alpine turning to valley and valley uplifting is visible in the studied area ,indicating various stages of paleotopography .Based on inversion of ancient landform and equilibrium correction , the equilibrium rebound would play an important role in the rock uplift during the Altai post-orogenic period.%对阿尔泰东南部地区磷灰石样品进行裂变径迹年龄分析及热历史演化模拟,分析计算岩体的隆升剥蚀速率及隆升剥蚀幅度,力求恢复古地形。裂变径迹年龄在(59.4±5.8)~(109.7±8.1)Ma之间变化,径迹长度为(12.0±2.5)~(13.7±1.5)μm。从热历史模拟结果可看出,总体上经历了三阶段的隆升-剥露热演化模式:108 M a之前的初始整体隆升阶段;108~28 M a的缓慢冷却阶段;28 M a以来的快速冷却过程,冷却速率为1.25~1.61℃/M a ,剥蚀量为1.17~1.50 km ,是本区剥露最快时期。对所有样品单颗粒年龄及混合年龄进行分析统计得到4组年龄,这种年龄不

  19. Measurement of solid state nuclear tracks in apatite by thermal analysis method

    Institute of Scientific and Technical Information of China (English)

    HE ShaoRong; YANG TongSuo; LI TianXiang; LU BaiZuo; JI ShuLi; HENG ShuYun

    2009-01-01

    A new measurement method of thermal analysis for solid state nuclear tracks is proposed. The an-nealing heat emitted by the unit mass of solid state nuclear tracks in heavy particles of the sample is determined via micro-thermal analysis method. Hence, the number of solid state nuclear tracks in the unit mass of sample is determined. In particular, this paper introduces the method and its significance to measure the number of a-particles nuclear tracks in apatite by measuring the annealing heat of a-particles nuclear tracks. In addition, the mechanism of the measurement and potential applications are discussed.

  20. Characteristics of diallyl phthalate resin as a fission track detector

    CERN Document Server

    Tsuruta, T

    1999-01-01

    Diallyl phthalate (DAP) resin plates were irradiated with fission fragments, and then etched in aqueous solution of KOH. Etched tracks were observed and counted by using an optical microscope. The detection efficiency of fission fragments was about 100% for both perpendicular and random incidence. DAP plates were insensitive to alpha particles and fast neutrons. These characteristics are suitable for detecting selected fission fragments, which coexist with alpha particles or fast neutrons. DAP plates are valuable for quantitative analysis of fissionable materials and neutron dosimetry. DAP and allyl diglycol carbonate (CR-39) were formed into copolymers in various ratios. The copolymers showed intermediate characteristics between DAP and CR-39. The fabrication of the copolymers made it possible to control the discrimination level for detection of heavy charged particles.

  1. Chrono-thermométrie par traces de fission : une perspective nouvelle pour la prospection pétrolière Chronothermometry by Fission-Track Dating: New Means for Petroleum Prospection

    Directory of Open Access Journals (Sweden)

    Storzer D.

    2006-11-01

    Full Text Available La propriété caractéristique des traces de fission d'enregistrer les paléotempératures offre la possibilité unique de caler des événements thermiques dans leur contexte géologique et donc de modéliser quantitativement les histoires thermiques des roches. Le thermomètre traces de fission-apatite enregistre les paléo-températures dans un intervalle compris entre 30 et 170°C, domaine qui inclut les températures généralement retenues pour la genèse optimale des hydrocarbures liquides. La formation, la maturation et la destruction des hydrocarbures, de la même façon que la guérison des traces latentes, sont fonction des deux paramètres temps et températures; en conséquence, l'étude détaillée de l'effacement progressif des traces latentes fossiles dans les apatites en fonction de leur profondeur dans un puits, conduit à des indications précises sur les variations de la température en fonction du temps à l'intérieur de la fenêtre à huile. Ces deux informations sont obtenues en combinant la datation traces de fission-isochrone et les analyses de longueurs des traces de fission. Le potentiel de la méthode des traces de fission dans son application à la reconstitution de l'histoire thermique des bassins sédimentaires est illustré à partir de l'analyse d'apatites détritiques provenant des bassins intérieur et côtier du Gabon d'une part et du bassin d'Otway en Australie du Sud d'autre part. The characteristic property of fission tracks to record paleotemperatures provides a unique possibility of setting thermal events in their geological context and hence of quantitatively modeling the thermal histories of rocks. The fission track apatite-thermometer records paleotemperatures in the interval between 30 and 170°C, a range that includes the temperatures generally considered to be required for the optimum formation of liquid hydrocarbons. The formation, maturation and destruction of hydrocarbons, as well as the

  2. Etchability of Latent Fission Fragment Tracks in CR-39

    Institute of Scientific and Technical Information of China (English)

    Mukhtar Ahmed Rana

    2007-01-01

    We report the chemical etching behaviour of the CR-39 polymer detector exposed to fission fragments of 252 Cf describing etchability of latent tracks, which are like nanocylinders. The fission fragment exposed detectors were etched in 1-7N NaOH water solutions at temperatures 50-80°C for 45 min in the case of track length and 180min in the case of track diameter measurements. The reduced etch rate S (called here etchability) is determined using experimental results for all etching conditions and the etching conditions with the highest reduced etch are obtained. Physics and energetics of bulk and track etching are discussed. Possible effects causing spurious changes in determination of activation energy of etching are investigated.

  3. Fission track dating of mesozoic sandstones and its tectonic significance in the Eastern Sichuan Basin, China

    Energy Technology Data Exchange (ETDEWEB)

    Shen Chuanbo, E-mail: cugshen@yahoo.c [Key Laboratory of Tectonics and Petroleum Resources, China University of Geosciences, Ministry of Education, Wuhan 430074 (China); Faculty of Earth Resources, China University of Geosciences, Wuhan, Hubei Province 430074 (China); Mei Lianfu [Key Laboratory of Tectonics and Petroleum Resources, China University of Geosciences, Ministry of Education, Wuhan 430074 (China); Xu Sihuang [Faculty of Earth Resources, China University of Geosciences, Wuhan, Hubei Province 430074 (China)

    2009-10-15

    To establish the tectonic evolution of the eastern Sichuan basin, apatite fission track dating and time-temperature thermal history modeling were carried to analyze on 11 samples collected from Jurassic sandstones. The results indicate that the cooling and exhumation process of the eastern Sichuan basin can be divided into three stages since Cretaceous, (1) a rapid cooling phase between approx100 and approx70 Ma, (2) following by a period of relative thermal stability phase between approx70 and approx15 Ma, (3) and then a new rapid cooling stage after approx15 Ma. Two rapid cooling events imply that the eastern Sichuan basin once underwent two tectonic movements since Cretaceous. The first rapid cooling is associated with Mesozoic tectonic reactivation beginning at 100 Ma, which result in folds and faults of the eastern Sichuan basin. The second tectonic movement occurred at 15 Ma, which is related to denudation by compression resulting from the eastward growth of Tibetan plateau uplift.

  4. Cooling age of Dabie orogen, China, determined by 40Ar-39Ar and fission track techniques

    Institute of Scientific and Technical Information of China (English)

    陈江峰; 谢智; 刘顺生; 李学明; K.A.Foland

    1995-01-01

    Based on 40Ar-39Ar results of hornblendes and biotites and fission track dating results of apatites separated from the same rock samples, cooling history of rocks from Dabie orogen is discussed. Rocks from both Southern Dabie Terrain (SDT) and Northern Dabie Terrain (NDT) have an early fast cooling followed by a more recent slow cooling. Rocks from SDT cooled to about 540℃ at about 190 Ma B.C., while rocks from NDT cooled to about 540℃ at 125 Ma B C. Until about 110-120 Ma B.C., rocks from both SDT and NDT cooled to about 100℃. This suggests that a relative movement among rocks from SDT, NDT and ul-Ira-high pressure metamorphic rocks exis-ts before 110-120 Ma B.C.

  5. Apatite Fission Track Evidence for the Mesozoic-Cenozoic Tectonic Uplift of Aqishan-Yamansu Area, East Tianshan:With Discussion of Tectonic Activity and Geological Disposal of Radioactive Waste%阿齐山--雅满苏地区中-新生代构造隆升裂变径迹证据:兼论构造活动对核废选址场的意义

    Institute of Scientific and Technical Information of China (English)

    刘红旭; 王永文; 赵建; 颜丹平; 何建国; 陈峰; 高洪雷; 所世鑫; 王勋; 张晓; 曹清艳

    2014-01-01

    Tectonic activity is a fundamental discriminant factor in site assessment for radioactive waste. The tectonic activity of geological repository of radioactive waste which is located at Aqishan-Yamasu in the East Tianshan was evaluated through model studying the uplift and exhumation history by the apatite fission track dating. The result shows that apatite fission track pool-age data range from 81.7 to 51.4 Ma which recorded a cooling event of the East Tianshan during the Late Cretaceous to Eocene, which is consistent with a tectonic uplift and denudation event in the Late Cretaceous in the Tianshan. The mean track lengths range from 13.60±0.11 to 14.36±0.10 μm with the standard deviations of 0.98 ~1.22 μm, which suggests that most tracks didn’ t experience thermal annealing process after they were formed. Based on evaluated geothermal gradient, the mean exhumation rate in the East Tianshan during the Late Cretaceous to Eocene was calculated to reach 270~580 m/Ma. The geological data and further temperature-time modeling of apatite was conducted, indicating that an exhumation event existed from the Late Cretaceous to Eocene (84~49 Ma); after 50 Ma, the crust of the east Tianshan has been in a steady state, and the Cenozoic tectonic activity in Aqishan-Yamansu area has become significantly weaker than other area of Tianshan. The study shows that the geomorphologic features of present Tianshan inherit that from the Late Cretaceous, and weak tectonic activity conforms to the tectonic requirements of geological disposal of radioactive waste.%构造活动性是核废处置场评价的一项基本判别要素。文中通过对东天山阿齐山-雅满苏地区磷灰石裂变径迹测年及构造隆升剥蚀过程的模拟来评价核废处置场的构造活动性。结果表明阿齐山-雅满苏地区样品磷灰石裂变径迹年龄集中分布在81.7~51.4 Ma之间,反映出东天山地区晚白垩世-始新世存在一次明显的构造冷却事件,这与

  6. Fission track studies on some minerals and water of the north-east India

    Science.gov (United States)

    Singh, Thoudam Nandababu

    The present work is aimed at the geochronological investigations of the minerals of some granitic rocks and estimation of uranium contents in minerals, rocks and water of some parts of the North-East India with the help of fission track (FT) technique. The study includes FT dating of minerals from granites of four different plutons and from pegmatites of two different regions of Meghalaya, annealing studies of the minerals including the correction of the observed mineral ages and calculation of the cooling and uplift rates of the rocks. Precision on the errors of the mineral ages has also been studied in detail in the present work. The experiment was carried out at the Research laboratories of the Physics and the Geology Departments, Gauhati University, Assam, India during 1981-1984. Experimental results show four different age groups of the minerals which would reflect meaningful geological events in the history of these rocks. Sphenes of the Nartiang and Dawki granites record the highest FT ages ~ 1120 m.y. which may be linked with a major plutonic event. Muscovites of the Nartiang and Jowai pegmatites measure ages ~ 690 m.y. which may correspond to the time of emplacements of these pegmatites. Apatites of the Nartiang granites show FT ages ~ 470 m.y. which falls within the period of Indian Ocean cycle event. But, apatites of the Jowai, Pynursla and Dawki granites record the youngest ages ~ 90 m.y. which lies within the period of extrusion of cretaceous lavas (Sylhet traps). Apatite age of the Nartiang granite and muscovite ages of the Nartiang and Jowai pegmatites were corrected to ~ 510 m.y., ~ 743 m.y. and ~ 741 m.y. respectively by applying the plateau method of age correction. However, insignificant corrections were found in the sphene ages of the Nartiang and Dawki granites and apatite ages of the Jowai and Dawki granites. An interesting finding of the present work is the wide discrepancy between the apatite ages ~ 90 m.y. (Cretaceous) of Jowai, Pynursla

  7. Simulated fissioning of uranium and testing of the fission-track dating method

    Science.gov (United States)

    McGee, V.E.; Johnson, N.M.; Naeser, C.W.

    1985-01-01

    A computer program (FTD-SIM) faithfully simulates the fissioning of 238U with time and 235U with neutron dose. The simulation is based on first principles of physics where the fissioning of 238U with the flux of time is described by Ns = ??f 238Ut and the fissioning of 235U with the fluence of neutrons is described by Ni = ??235U??. The Poisson law is used to set the stochastic variation of fissioning within the uranium population. The life history of a given crystal can thus be traced under an infinite variety of age and irradiation conditions. A single dating attempt or up to 500 dating attempts on a given crystal population can be simulated by specifying the age of the crystal population, the size and variation in the areas to be counted, the amount and distribution of uranium, the neutron dose to be used and its variation, and the desired ratio of 238U to 235U. A variety of probability distributions can be applied to uranium and counting-area. The Price and Walker age equation is used to estimate age. The output of FTD-SIM includes the tabulated results of each individual dating attempt (sample) on demand and/or the summary statistics and histograms for multiple dating attempts (samples) including the sampling age. An analysis of the results from FTD-SIM shows that: (1) The external detector method is intrinsically more precise than the population method. (2) For the external detector method a correlation between spontaneous track count, Ns, and induced track count, Ni, results when the population of grains has a stochastic uranium content and/or when the counting areas between grains are stochastic. For the population method no correlation can exist. (3) In the external detector method the sampling distribution of age is independent of the number of grains counted. In the population method the sampling distribution of age is highly dependent on the number of grains counted. (4) Grains with zero-track counts, either in Ns or Ni, are in integral part of

  8. Fission track ages and Exhumation mechanisms of the Tauern Window, Eastern Alps

    Science.gov (United States)

    Bertrand, Audrey; Rosenberg, Claudio; Garcia, Sebastian

    2010-05-01

    The Tauern Window (TW) is a thermal and structural dome which exposes Penninic basement, its cover units as well as parts of the overlying Austroalpine basement in the central part of the Eastern Alps. The peak of metamorphism was attained approximately at 30Ma (Selverstone et .al, 1992), followed by cooling and exhumation throughout Miocene time. Most of the tertiary exhumation of the Eastern Alps was localized in the TW, from Early Oligocene to late Miocene time. A current debate centers on the exhumation mechanisms of Penninic rocks in the core of the TW, namely to assess whether orogen-parallel extension (e.g., Selverstone, 1988) or a combination of folding and erosion (eg., Rosenberg et al., 2004) with subordinate extension were the controlling processes. E-W extension is well documented at the western (Brenner Fault) and eastern (Katschberg Fault) margins of the window (e.g., Behrmann, 1988; Selverstone, 1988; Genser and Neubauer, 1989). In contrast, upright folding dominates the internal structure of the dome, and in particular along its western part, where fold amplitudes, mostly eroded during folding, attained up to 10 km. This study attempts to assess the relative importance of folding and erosion and of orogen-parallel extension during exhumation by analyzing the spatial and temporal cooling patterns of apatite and zircon fission track ages. The compilation of published apatite and zircon fission track ages indicates a concentric younging of both the apatite and zircon ages toward the core of the TW. The concentric isochrones follow the map trace of the axial planes of the upright folds of the western and eastern TW. This cooling pattern is in contrast to the one expected by a process of extensional unroofing, which in map view would results in isochrons parallel to the extensional faults and progressively younging towards them (e.g., Foster et al., 2001). We therefore propose that folding and erosion were primarily responsible for exhuming the Penninic

  9. Fission-track analysis of meteorites: Dating of the Marjalahti pallasite

    Energy Technology Data Exchange (ETDEWEB)

    Bondar, Yu.V. [Institute of Environmental Geochemistry, 34a Palladin ave., Kiev 03142 (Ukraine)]. E-mail: juliavad@yahoo.com; Perelygin, V.P. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation)

    2005-11-15

    The results of the Marjalahti pallasite fission-track age determination are presented. Thorough examination of fossil tracks in the phosphate (whitlockite) crystals coupled with U-content determination in whitlockites can make it possible to estimate the contributions of all possible track sources to the total track density and to calculate a model fission-track age. It is found that whitlockite crystals of the Marjalahti pallasite contain fossil tracks due to galactic cosmic rays (VH, VVH nuclei); fission of U and Th induced by cosmic rays; spontaneous fission of {sup 238}U; and spontaneous fission of extinct, short-lived {sup 244}Pu present in significant quantities in the early solar system. A great track density attributed to the extinct {sup 244}Pu testifies to the high fission-track age. The model fission-track ages of (4.31+/-0.02)x10{sup 9}yr for the Marjalahti pallasite are calculated. Petrographic studies allow us to interpret the fission-track age as the time of the last shock/thermal event in the cosmic history of the pallasite.

  10. Lateral Variations of Fission-Track Cooling Ages along the Southern Peruvian Coast Reveal Coast-Parallel Extension during the Eocene and Oligocene.

    Science.gov (United States)

    Noury, M.; Bernet, M.; Jaillard, E.; Sempere, T.

    2014-12-01

    Proterozoic metamorphic rocks largely crop out between ~14 and ~17°S along the coast of southern Peru. Previous thermochronological studies in this belt focused on the Late Neogene cooling history and yielded Late Paleozoic to mid-Cretaceous zircon U-Th/He and fission-track ages, and Late Cretaceous to Early Paleocene apatite fission-track ages. Our study aims at extending the fission-track database in the ~300 km-long, high-grade metamorphic Atico-Mollendo Block (AMB; 15.8-17.1°S), in order to understand the lateral variations of thermochronologic ages along the Pacific coast of southern Peru. We present new apatite and zircon fission-track ages from the AMB and interpret them along with the previously published dates from this block and its surrounding areas. The apatite fission-track data show a longitudinal variation pattern with two localized shifts from younger (60 Ma) to older (~90 Ma) dates, corresponding to the northwestern and southeastern borders of the AMB. These shifts coincide in the field with two major normal fault zones that strike perpendicular to the coast and bound the AMB, and had been understated until now. Given the offsetted ages, the faults were active after 60 Ma, and tilted the AMB down to the NW. This interpretation is consistent with the fact that the metamorphic grade of the basement increases towards the SE, and with the deposition between ~55 and 30 Ma of forearc continental deposits (Lower Moquegua Group) that exhibit numerous synsedimentary extensional features. The zircon fission-track age pattern is more complicated but can be interpreted either as (i) reflecting a partial reset of the whole area due to burial during the Jurassic and Early Cretaceous, or (ii) as the reactivation of an important Carboniferous detachment fault during the ~100-80 Ma interval. We suggest that this coast-parallel Eocene-Oligocene extension accommodated the counterclockwise block rotation of the southern Peruvian forearc that accompanied the

  11. Absolute fission yields in the fast neutron induced fission of sup 2 sup 3 sup 3 U by track etch combined with gamma-ray spectrometry

    CERN Document Server

    Ramaswami, A; Kalsi, P C; Dange, S P

    2003-01-01

    The absolute fission yields of twenty seven fission products were determined in the fast neutron induced fission of sup 2 '3 sup 3 U, employing track etch in combination with gamma-ray spectrometry. The total number of fissions was measured by registering the fission tracks on a small strip of lexan, a solid state track detector. The fission products were analysed by gamma-ray spectrometry. The measured yield values were compared to the ENDF/B-VI compilation and show a good agreement. (author)

  12. Etching zircon age standards for fission-track analysis

    Energy Technology Data Exchange (ETDEWEB)

    Garver, J.I. E-mail: garverj@union.edu

    2003-02-01

    Nineteen laboratories that routinely measure fission-track ages in zircon were surveyed as to their principal methodology used for track revelation using chemical attack and counting procedures. The survey results show the following: (a) researchers in most labs count fission tracks with a optical microscope using at a total magnification between 1250x and 1600x ({approx}80%) with about an equal number using either a dry or oil objective (b) the majority of laboratories etch zircon with a KOH:NaOH eutectic heated in an oven between temperatures of 210 deg. C and 230 deg. C; (c) ag standards in zircon analysis do not have uniformly accepted etch times. Etching times for the widely used 28 Ma Fish Canyon Tuff (FCT) (4-60 h) and the lesser-used 16 Ma Buluk Tuff (13-55 h) vary significantly from lab to lab. Between {approx}220 deg. C and 230 deg. C, the principal range fo etching times for the FCT is between 20 and 30 h, and the mode for the Buluk Tuff is between 30 and 55 h. Three or fewer labs report etching times for the Tardee Rhyolite (22-40 h), the Bishop Tuff (10-46 h), and the Mt. Dromedary Banite (5-24 h). Variation in etching times may result in a bias in U-content which affects counting statistics. If etching is successful, strict criteria must be followed to ensure that the analyst only counts well-etched grains and that all tracks are successfully identified.

  13. 青藏高原东缘甘孜地区新生代隆升过程之磷灰石裂变径迹证据%Apatite fission track evidence for the Cenozoic uplift process in Garze area on the eastern margin of the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    王一伟; 梅刚; 谢启兴; 周晓珂; 王刚

    2015-01-01

    通过青藏高原东缘甘孜地区7件砂岩磷灰石样品裂变径迹分析,取得了测试样品的表观年龄,运用模拟退火法对所有样品进行了热史模拟,获得了样品的热演化史;分析出甘孜地区在新生代古近纪以来经历了相似的构造演化过程,强构造隆升阶段分别发生在古近纪46~30 Ma间和新近记9 Ma以来,平均抬升速率和平均抬升量分别为1261 m/Ma、2634 m和388 m/Ma、1043 m;甘孜地区构造隆升具有不平衡性、阶段性、地区性差异,冷却速率、抬升速率和抬升幅度也存在偏差。%Based on fission track analysis of seven samples from Garze area on the eastern margin of the Tibetan Plateau, the authors obtained the apparent ages of the analyzed samples. Using the simulated annealing method, the authors made thermal history simulation for all samples, and obtained the thermal evolution history of these samples. According to the results obtained, the Garze area has experienced similar tectonic evolutions since Palaeogene, and the tectonic uplift occurred in 46-30 Ma and since 9 Ma of Neogene, with the uplift rate and average uplift amount being 1261 m/Ma, 2634 m and 388 m/Ma, 1043 m respectively. The tectonic uplifts in the Garze area are characterized by imbalance as well as stage and regional differences; in addition, there also exist deviations in cooling rate, uplift rate and uplift amplitude.

  14. Fission Track Geochronology of Xiaonanchuan Pluton and the Morphotectonic Evolution of Eastern Kunlun since Late Miocene

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Apatite fission track (AFT) thermochronology of seven samples from the Xiaonanchuan(小南川) pluton in the Kunlun (昆仑) pass area was carried out, for the purpose of determining the timing of cooling and the relation between the exhumation and the morphotectonic processes. The AFT ages yield low denudation rates of 0.020-0.035 mm/ a during the late Miocene, which correspond to a stable geomorphic and weak tectonic uplifting environment. The low denudation rates can be considered as the approximate tectonic uplifting rates. The AFT geochronology shows paroxysmally rapid cooling since the Pliocene and an apparent material unroofing of more than 3 km in the Xiaonanchuan area. This was not the result of simple denudation. The rapid cooling was coupled with the intensive orogeny since the Pliocene, which was driven by tectonic uplifting. The accelerated relief building was accompanied by a series of faulting, which caused the basin and the valley formation and sinking. The space pattern of the AFT ages also shows differential uplifting, which decreases northwardly. This trend is supported by the regional AFT data, which indicate that the exhumation decreases northwardly in eastern Kunlun. This trend also exists in east-west orientation from the western Kunlun range to the eastern. The uplifting trend is also supported by geomorphic characteristics including the elevation and the relief differences as well as the distribution of the Late Cenozoic volcanism.

  15. Fission track evidence for the Mesozoic-Cenozoic tectonic uplift of Mt. Bogda, Xinjiang, Northwest China

    Institute of Scientific and Technical Information of China (English)

    SHEN Chuanbo; MEI Lianfu; PENG Lei; ZHANG Shiwan; LIU Lin; TANG Jiguang

    2006-01-01

    Fission-track dating evidence from 5apatite samples and 4 zircon samples, and modeled time-temperature thermal history indicate that since Late Jurassic-Cretaceous (150 -106 Ma), the uplift process of Mt. Bogda can be divided into four stages of thermal evolution: 150 - 106, 75 -65, 44 -24and 13 -9 Ma. Before 44- 24 Ma, the cooling rate and uplifting rate of the southern and northern segments of Mt. Bogda are almost the same, showing that the uplifting of Mt. Bogda is an overall process.Since 44 - 24 Ma, the uplifting of the southern and northern segments of Mt. Bogda has shown differences. During 42 - 11 Ma, the northern segment of Mt. Bogda was at a steady stage, with the cooling rate being 0.03℃/Ma and the uplifting rate being 0. 001 mm/a. From 11 Ma to the present, the northern segment of Mt. Bogda was at a rapid cooling and uplifting stage, with the cooling rate being 5.72℃/Ma and the uplifting rate being 0.19 mm/a. However, the southern segment of Mt. Bogda has been at a rapid cooling and uplifting stage since 26 Ma, with the cooling rate being 1.24℃/Ma and the uplifting rate being 0.041 mm/a during 26 -9 Ma; 4.88℃/Ma and 0. 163 mm/a from 9 Ma till now.

  16. Fission track dating of the Cenozoic uplift in Mabian area, southern Sichuan Province, China

    Institute of Scientific and Technical Information of China (English)

    AN YanFen; HAN ZhuJun; WAN JingLin

    2008-01-01

    The apparent ages of samples are obtained from fission track dating of apatite samples collected from the fault zones in Mabian area, southern Sichuan Province.In addition, thermal history is simulated from the obtained data by applying AFTSolve Program, to acquire the thermal evolution history of the samples.The result shows that tectonically the Mabian area was relatively stable between 25 and 3 Ma, compared to the inner parts and other marginal areas of the Tibetan Plateau.The studied area had little response to the rapid uplift events that occurred for several times in the Tibetan Plateau during 25-3 Ma.The latest thermal event related to the activity of the Lidian fault zone (about 8 Ma) is later than that of the Ebian fault zone (18-15 Ma ) to the west, indicating to some extent that the evolution of fault activity in the Mabian area has migrated from west to east.The latest extensive tectonic uplift occurred since about 3 Ma.As compared with the Xianshuihe fault zone, the Mabian area is closer to the eastern margin of the plateau, while the time of fast cooling event in this area is later than that in the southeast segment of the Xianshuihe fault zone (3.6-3.46 Ma).It appears to support the assumption of episodic uplift and stepwise outward extension of the eastern boundary of the Tibetan Plateau in late Cenozoic.

  17. Cenozoic pulsed deformation history of northeastern Tibetan Plateau reconstructed from fission-track thermochronology

    Science.gov (United States)

    Wang, Xiuxi; Song, Chunhui; Zattin, Massimiliano; He, Pengju; Song, Ai; Li, Jijun; Wang, Qiangqiang

    2016-03-01

    The synorogenic basin deposits and bedrocks of their source terranes within and along the Tibetan Plateau contain fundamental information regarding the spatiotemporal evolution of the largest orogenic plateau on Earth. The Guide-Xining region is located on the northeastern portion of the Tibet and its Eocene-early Pleistocene basin succession is well preserved. By integrating apatite fission-track thermochronology from sedimentary and basement samples, with heavy minerals and paleocurrent data, we decipher an almost complete sequence of exhumation and depositional events during the Cenozoic. Our data indicates that the initial deformation along the Guide-Xining region occurred since the Eocene, with the reorganization of the regional tectonomorphology and the formation of a broad basin. Thereafter, this single large basin was disrupted by multiple episodes of exhumation and deformation. Our study illuminate that the multiple-stage active processes (occurred at 49-42, 36-32, 23-19, 16-13 and 8-4 Ma) work together to produce the current NE Tibetan Plateau.

  18. Fission track dating of the Cenozoic uplift in Mabian area, southern Sichuan Province, China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The apparent ages of samples are obtained from fission track dating of apatite samples collected from the fault zones in Mabian area, southern Sichuan Province. In addition, thermal history is simulated from the obtained data by applying AFT Solve Program, to acquire the thermal evolution history of the samples. The result shows that tectonically the Mabian area was relatively stable between 25 and 3 Ma, compared to the inner parts and other marginal areas of the Tibetan Plateau. The studied area had little response to the rapid uplift events that occurred for several times in the Tibetan Plateau during 25-3 Ma. The latest thermal event related to the activity of the Lidian fault zone (about 8 Ma ) is later than that of the Ebian fault zone (18-15 Ma ) to the west, indicating to some extent that the evolution of fault activity in the Mabian area has migrated from west to east. The latest extensive tectonic uplift occurred since about 3 Ma. As compared with the Xianshuihe fault zone, the Mabian area is closer to the east- ern margin of the plateau, while the time of fast cooling event in this area is later than that in the southeast segment of the Xianshuihe fault zone (3.6-3.46 Ma ). It appears to support the assumption of episodic uplift and stepwise outward extension of the eastern boundary of the Tibetan Plateau in late Cenozoic.

  19. The evidence of fission-track data for the study of tectonic thermal history in Qinshui Basin

    Institute of Scientific and Technical Information of China (English)

    REN Zhanli; XIAO Hui; LIU Li; ZHANG Sheng; QIN Yong; WEI Chongtao

    2005-01-01

    The thermal history of the Qinshui Basin has been studied by using the fission-track analysis of apatite and zircon, integrated analysis of tectonic evolution, magmatic activity and other palaeogeothermal analysis data. Results indicate that the palaeogeothermal gradient between the latePaleozoic era and the medium-Mesozoic era is relatively low and the palaeogeothermal gradient in the late-Mesozoic is up to 5.56℃/100 m in the middle, and the values are relatively higher in the north and south margins of the basin, reaching over 8.00℃/100 m, which indicates that there was an anomalous tectonic thermal event in the thermal history of Qinshui Basin. This event happened in 110- 140 Ma, and the main peak value was between 120 and 140 Ma. This anomalous tectonic thermal event is controlled by the strengthening thermal mobility of the lithosphere and magmatic intrusion.The maturity of the Permo-Carboniferous coal series mainly was controlled by this anomalous thermal field. The apatite fission track date of samples across the basin shows that a rapid tectonic uplifting with cooling existed 26.2-11.5 Ma ago and the upliftings in the north and south of the basin happened earlier than that in the middle. The Permo-Carboniferous strata had been completely annealed in the early 50 Ma, palaeotemperature over 125℃. Since then, especially from Oligocene-Miocene epoch, the strata which experienced large-scale tectonic upliftings with rapid cooling have been kept out of the annealing belt (70-125℃) in a relative low temperature environment. The late Mesozoic tectonic thermal event control hydrocarbon production peak (late Jurassic to early Cretaceous period) of Permo-Carboniferous strata in Qinshui Basin. When the strata experienced upliftings with rapid cooling since Oligocene-Miocene epoch, the hydrocarbon generation of coal series had stopped.

  20. Cretaceous—Quaternary tectonic evolution of the Tatra Mts (Western Carpathians: constraints from structural, sedimentary, geomorphological, and fission track data

    Directory of Open Access Journals (Sweden)

    Králiková Silvia

    2014-08-01

    Full Text Available The Tatra Mts area, located in the northernmost part of Central Western Carpathians on the border between Slovakia and Poland, underwent a complex Alpine tectonic evolution. This study integrates structural, sedimentary, and geomorphological data combined with fission track data from the Variscan granite rocks to discuss the Cretaceous to Quaternary tectonic and landscape evolution of the Tatra Mts. The presented data can be correlated with five principal tectonic stages (TS, including neotectonics. TS-1 (~95-80 Ma is related to mid-Cretaceous nappe stacking when the Tatric Unit was overlain by Mesozoic sequences of the Fatric and Hronic Nappes. After nappe stacking the Tatric crystalline basement was exhumed (and cooled in response to the Late Cretaceous/Paleogene orogenic collapse followed by orogen-parallel extension. This is supported by 70 to 60 Ma old zircon fission track ages. Extensional tectonics were replaced by transpression to transtension during the Late Paleocene to Eocene (TS-2; ~80-45 Ma. TS-3 (~45-20 Ma is documented by thick Oligocene-lowermost Miocene sediments of the Central Carpathian Paleogene Basin which kept the underlying Tatric crystalline basement at elevated temperatures (ca. > 120 °C and < 200 °C. The TS-4 (~20-7 Ma is linked to slow Miocene exhumation rate of the Tatric crystalline basement, as it is indicated by apatite fission track data of 9-12 Ma. The final shaping of the Tatra Mts has been linked to accelerated tectonic activity since the Pliocene (TS-5; ~7-0 Ma.

  1. Spatiotemporal variation in exhumation of the Crystallines in the NW-Himalaya, India: Constraints from fission track dating analysis

    Science.gov (United States)

    Patel, R. C.; Adlakha, Vikas; Lal, Nand; Singh, Paramjeet; Kumar, Y.

    2011-05-01

    During Himalayan orogeny, coeval thrusting along the Main Central/Munsiari Thrust (MCT/MT) and extension along the South Tibetan-Detachment System (STDS) are widely responsible for rapid exhumation of the Higher Himalayan Crystalline (HHC) zone. Apatite and zircon fission-track data along the Kaliganga and Darma valleys in the Kumaon Himalaya serve to document the shallow bedrock exhumation history of the HHC. Taking into account sample location within the HHC with respect to the MCT/MT, the apatite fission track (AFT) data-sets along the Darma (1.0 ± 0.1 to 2.8 ± 0.3 Ma) and Kaliganga (1.4 ± 0.2 to 2.4 ± 0.3 Ma) which are sharing same structural setting and rock types and being separated by 40 km, show very similar patterns of exhumation histories since Plio-Quaternary in the Kumaon Himalaya. Data sets along Darma and Kaliganga are very similar to data set of adjacent traverse (50 km away) along the Goriganga valley studied by Patel and Carter (2009). Whole data sets within the HHC in Kumaon Himalaya provide clear evidence for Plio-Quaternary tectonic activity along the Vaikrita Thrust (VT). Precipitation in this region exerts a strong influence on erosional surface processes. Fluvial erosional unloading along the Himalaya is focused on the high mountainous region of the HHC, where the orographic barrier forces out the maximum percentage of annual rainfall. FT cooling ages reveal coincidence between rapid erosion and exhumation that is focused in a ~ 25-30 km wide sector of the HHC, rather than covering the entire orogen. Similarity of AFT age pattern and exhumation rates along all three major traverses (Goriganga, Darma and Kaliganga) indicates that the region has been experiencing constant rate of crustal uplift and erosion since long time. Comparison of fission track ages from the Kumaon Himalaya with other segments of the NW-Himalaya shows spatiotemporal variation in exhumation. It is described due to the development of local structures such as dome

  2. Obsidian dating by fission track method; Datacao de obsidianas com o metodo dos tracos de fissao

    Energy Technology Data Exchange (ETDEWEB)

    Araya, A.M.O.

    1990-12-01

    The fission track method was employed to obtain the age of twelve obsidian sample from Ecuador. By using the plateau-age correction method, we obtained the true age of each sample and were able to identify four groups of ages in the studied area. Thereafter we studied the fading of fission tracks in two obsidian samples with different origins: Yanaurcu, Ecuador and Monte Arci, Italy. We constructed Arrhenius plots and calculated activation energies for both samples. The results from thermal annealing experiments were compared with theoretical curves obtained by integrating an equation proposed by Shukolyukov et al (1965). (author). 43 refs, 20 figs, 10 tabs.

  3. A numerical model for the thermal history of rocks based on confined horizontal fission tracks

    DEFF Research Database (Denmark)

    Jensen, Peter Klint; Hansen, Kirsten; Kunzendorf, Helmar

    1992-01-01

    A numerical model for determination of the thermal history of rocks is presented. It is shown that the thermal history may be uniquely determined as a piece-by-piece linear function on the basis of etched confined, horizontal fission track length distributions, their surface densities, and the ur......A numerical model for determination of the thermal history of rocks is presented. It is shown that the thermal history may be uniquely determined as a piece-by-piece linear function on the basis of etched confined, horizontal fission track length distributions, their surface densities...

  4. Fission-track-age records of the Mesozoic tectonic-events in the southwest margin of the Ordos Basin, China

    Institute of Scientific and Technical Information of China (English)

    CHEN; Gang; SUN; JianBo; ZHOU; LiFa; ZHANG; HuiRuo; LI; XiangPing; WANG; ZhiWei

    2007-01-01

    Based on the analysis of apatite and zircon fission track (FT), the FT age distribution and the peck-ages of the Mesozoic tectonic events in the southwest margin of the Ordos Basin (OB) were discussed. (1) The early event mainly occurred at 213-194 Ma with a peck-age of 205 Ma, and corresponded to the tectonic uplift and the mega-clastic deposit in the southwest OB during the Late Triassic. (2) The middle event included at least two episodes. One was at 165-141 Ma with a peck-age of 150 Ma, and the other was at 115-113 Ma with a peck-age of 114 Ma, corresponding to the over-thrusting and the mega- clastic deposits in the southwest OB during the Late Jurassic to the Early Cretaceous. (3) The late event mainly demonstrated the regional uplifting and included at least two episodes. One was at 100-81 Ma with a peck-age of 90 Ma, and the other was at 66-59 Ma with a peck-age of 63 Ma. Additionally, the relationship analysis of the tectonic event and the mineralizing chronology revealed that the extreme environment of the peck-age event and the subsequent moderate activity could be the key factors of the multiple resources coupling and coexistence in the OB.

  5. Late Cretaceous-Cenozoic exhumation history of Tiantangzhai region of Dabieshan Orogen: Constraints from (U-Th)/He and fission track analysis

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Integrated fission track and (U-Th)/He analysis is carried out on 6 apatite and 6 zircon samples from a near vertical section in The Tiantangzhai region at the core of the present Dabieshan orogen. The result shows that the region experienced cooling/exhumation during the Late Cretaceous and Early Tertiary period. Age-elevation relationships for different dating systems and different minerals suggest a pulse of rapid exhumation at ~110 Ma before present, preserved in the structurally highest samples. At lower elevations, ages begin to decrease with decreasing elevation, suggesting lower exhumation rates since 90 Ma. Two periods of different exhumation rates are identified since 90 Ma. The average apparent exhumation rate for the period of 43.4-22.5 is 0.062 km/Ma, whereas that for the period of 76.4-47.4 Ma is 0.039 km/Ma.

  6. Late Mesozoic and Cenozoic thermotectonic evolution of the central Brooks Range and adjacent North Slope foreland basin, Alaska: Including fission track results from the Trans-Alaska Crustal Transect (TACT)

    Science.gov (United States)

    O'Sullivan, P. B.; Murphy, J.M.; Blythe, A.E.

    1997-01-01

    Apatite fission track data are used to evaluate the thermal and tectonic history of the central Brooks Range and the North Slope foreland basin in northern Alaska along the northern leg of the Trans-Alaska Crustal Transect (TACT). Fission track analyses of the detrital apatite grains in most sedimentary units resolve the timing of structures and denudation within the Brooks Range, ranging in scale from the entire mountain range to relatively small-scale folds and faults. Interpretation of the results indicates that rocks exposed within the central Brooks Range cooled rapidly from paleotemperatures 110?? to 50??C during discrete episodes at ???100??5 Ma, ???60??4 Ma, and ???24??3 Ma, probably in response to kilometer-scale denudation. North of the mountain front, rocks in the southern half of the foreland basin were exposed to maximum paleotemperatures 110??C in the Late Cretaceous to early Paleocene as a result of burial by Upper Jurassic and Cretaceous sedimentary rocks. Rapid cooling from these elevated paleotemperatures also occurred due to distinct episodes of kilometer-scale denudation at ???60??4 Ma, 46??3 Ma, 35??2 Ma, and ???24??3 Ma. Combined, the apatite analyses indicate that rocks exposed along the TACT line through the central Brooks Range and foreland basin experienced episodic rapid cooling throughout the Late Cretaceous and Cenozoic in response to at least three distinct kilometer-scale denudation events. Future models explaining orogenic events in northern Alaska must consider these new constraints from fission track thermochronology. Copyright 1997 by the American Geophysical Union.

  7. Fission track astrology of three Apollo 14 gas-rich breccias

    Science.gov (United States)

    Graf, H.; Shirck, J.; Sun, S.; Walker, R.

    1973-01-01

    The three Apollo 14 breccias 14301, 14313, and 14318 all show fission xenon due to the decay of Pu-244. To investigate possible in situ production of the fission gas, an analysis was made of the U-distribution in these three breccias. The major amount of the U lies in glass clasts and in matrix material and no more than 25% occurs in distinct high-U minerals. The U-distribution of each breccia is discussed in detail. Whitlockite grains in breccias 14301 and 14318 found with the U-mapping were etched and analyzed for fission tracks. The excess track densities are much smaller than indicated by the Xe-excess. Because of a preirradiation history documented by very high track densities in feldspar grains, however, it is impossible to attribute the excess tracks to the decay of Pu-244. A modified track method has been developed for measuring average U-concentrations in samples containing a heterogeneous distribution of U in the form of small high-U minerals. The method is briefly discussed, and results for the rocks 14301, 14313, 14318, 68815, 15595, and the soil 64421 are given.

  8. Low-temperature thermal evolution of the Azov Massif (Ukrainian Shield Ukraine) — Implications for interpreting (U Th)/He and fission track ages from cratons

    Science.gov (United States)

    Danišík, Martin; Sachsenhofer, Reinhard F.; Privalov, Vitaliy A.; Panova, Elena A.; Frisch, Wolfgang; Spiegel, Cornelia

    2008-08-01

    The low-temperature thermal evolution of the Azov Massif (eastern part of the Ukrainian Shield, Ukraine) is investigated by combined zircon fission track (ZFT), apatite fission track (AFT) and apatite (U-Th)/He (AHe) thermochronology. The data help to better understand the geodynamic evolution of the Azov Massif and the adjacent intra-cratonic rift basin (Dniepr-Donets Basin) as follows: ZFT data reveal that the Precambrian crystalline basement of the Azov Massif was heated to temperatures close to ˜ 240 °C during the Late Palaeozoic. The heating event is interpreted in terms of burial of the basement beneath a several kilometres thick pile of Devonian and Carboniferous sedimentary deposits of the adjacent Dniepr-Donets Basin. During Permo-Triassic times, large parts of the basement were affected by a thermal event related to mantle upwelling, associated magmatic activity and increased heat flow in the adjacent rift. The major part of the basement cooled to near-surface conditions in the Early to Middle Triassic and since then was thermally stable as suggested by AFT and AHe data. Further, AFT data confirm Late Triassic magmatic activity in the Azov Massif, which, however, did not influence regional thermal pattern. The northern part of the basement and its sedimentary cover record a cooling event in the Jurassic, which was probably related to erosion. However, although Ar-Ar data of Jurassic magmatic activity in the Donbas Foldbelt are about 20 My younger than the AFT data, thermal relaxation after elevated heat flow associated with this magmatic event cannot be completely ruled out. Our results reveal apparent inconsistencies between AFT and AHe data: the AHe ages corrected for alpha ejection according to the standard procedure [Farley, K.A., Wolf, R.A., Silver, L.T., 1996. The effect of long alpha-stopping distances on (U-Th)/He ages. Geochim. Cosmochim. Acta 60(21), 4223-4229.; Farley, K.A., 2002. (U-Th)/He dating: Techniques, calibrations, and applications

  9. Measurement of the energy spectra of fission fragments using nuclear track detectors and digital image processing

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa, Guillermo; Golzarri, Jose I. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A.P. 20-364, Mexico D.F. 01000 (Mexico); Castano, Victor M., E-mail: castano@fata.unam.m [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Boulevard Juriquilla 3001, Santiago de Queretaro, Queretaro 76230 (Mexico)

    2010-08-15

    Energy spectra of fission fragments were determined using a Nuclear Track Methodology (NTM) supported by digital image analysis and numerical data processing using a standard personal computer. The analysis of a californium ({sup 252}Cf) spectrum with this approach shows improvement compared with the values reported previously using the standard procedure, in terms of resolution and accuracy. This new method adds full automation to the technical advantages and cost effectiveness of an NTM.

  10. Response studies of fission track detectors within moderators in CAVE A at GSI

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, S., E-mail: Sabine.Mayer@psi.c [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Boschung, M.; Fiechtner, A.; Hohmann, E. [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Fehrenbacher, G.; Radon, T.; Pleskac, R.; Wengenroth, M. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Planckstrasse 1, 64291 Darmstadt (Germany)

    2010-12-15

    At the Paul Scherrer Institut (PSI) fission track detectors are routinely used in moderators for determining the ambient dose equivalent in stray radiation fields due to neutrons. At the high-energy field CERF (CERN EU high-energy reference field) at CERN, the response of fission track detectors within two different moderators, where one moderator has an inlay of Pb to increase the response of the detector to high-energy neutrons, was surprisingly similar. To confirm this unexpected behaviour, a measurement campaign in another high-energy field, i.e. CAVE A at the Helmholtzzentrum fuer Schwerionenforschung (GSI) was carried out. CAVE A at GSI is one of few facilities where a stray radiation field with neutrons above 20 MeV can be generated under controlled conditions. Reference doses were obtained by simulating the stray radiation field in the measurement positions. These simulations were carried out independently by GSI and PSI using two different Monte Carlo codes, i.e. Fluka and MCNPX, respectively. In this paper the measurements at GSI are described in detail. The results are then compared to previous measurement campaigns in the radiation field of CERF as well as {sup 241}Am-Be and {sup 252}Cf radionuclide sources, which all feature different neutron spectra. None of these campaigns confirm the improvement in sensitivity of the Pb enhanced moderator compared to the PSI standard moderator in combination with fission track detectors.

  11. A Constraining Thermal History of Basin Fission-track Technology%一种约束盆地低温热历史的裂变径迹技术

    Institute of Scientific and Technical Information of China (English)

    张向涛; 张青林; 王绪诚; 阙晓铭; 陈会霞

    2012-01-01

    裂变径迹(FT)技术是根据矿物中铀裂变产生的辐射损伤特性进行分析的低温热年代技术。随着对FT退火行为和实验退火模型研究的深入,使得这一技术成为约束沉积盆地低温热历史的重要手段。Laslett等、Crowley等和Ketcham等先后提出3个重要的磷灰石FT实验退火模型,其中以Ketcham等的退火模型研究最为深入,它分析了磷灰石类型、时间、温度和化学成分对其径迹退火的影响,使用c轴投射径迹长度和Dpar等参数,形成了描述磷灰石FT多元动力学退火的数学模型。锆石FT与U-Th/He技术、Ro值、地表温度和地层年龄等,均是约束磷灰石FT热历史重建的重要约束条件,HeFTy(2009)是进行低温热历史模拟的主要软件之一。%Fission-track(FT) thermochronology is a low-temperature dating technique utilizing the damage property produced by uranium fission decay.As the advanced researches of annealing behavior,and laboratory annealing models,this technique,especially apatite fission-track,has become an important measure to constrain the thermal history of sedimentary basin.Among three main apatite fission-track annealing models proposed by Laslett et al.(1987),Crowley et al.(1991) and Ketcham et al.(1999),respectively,the last one is the most significant and widely-applied annealing model,which integrated the influence of time,temperature and chemical composition to various types of apatite,together using the c-axis projected track-length and Dpar.This apatite multi-kinetic fission-track annealing model by Ketcham et al.(1999) can be applied well to make thermal modeling,describing the temperature-time relation in the development of basin.Zircon FT,(U-Th)/He,apatite(U-Th)/He,Ro value,surface temperature,and stratigraphic age are all as constraints for fission-track thermal modeling,while the HeFTy(2009) is an excellent software for reconstruction of low-temperature thermal history.

  12. Fission Track Dating of Authigenic Quartz in Red Weathering Crusts of Carbonate Rocks in Guizhou Province

    Institute of Scientific and Technical Information of China (English)

    LIU Xiuming; WANG Shijie; ZHANG Feng

    2004-01-01

    The Cenozoic evolution history of Guizhou Province, which is located on the southeastem flank of the Qinghai-Tibet Plateau, is unclear because of the lack of sedimentation records. The red weathering crusts widespread on the Yunnan-Guizhou Plateau may bear critical information about their evolution history. This work firstly determined the ages of four red weathering crusts in eastern, central and northern Guizhou. The material used in fission track dating is well-crystallized quartz occurring in many in-situ weathering crusts of carbonate rocks. The results showed that the fission track ages of quartz vary over a wide range from 1 to 25 Ma in the four profiles, significantly younger than the ages of the Triassic and Cambrian parent rocks. In combination with the evolution history of the regional geology during the period from 25 to 1 Ma, the ages of quartz can exclude the possibility that the origin of quartz has nothing to do with primary clastic minerals in parent rocks, authigenesis during diagenesis and hydrothermal precipitation or replacement by volcanic activities. It is deduced that the well-crystallized quartz was precipitated from Si-rich weathering fluids during the weathering process of carbonate rocks. The recorded ages of quartz from the four profiles are consistent with the episodes of the planation surfaces on the Qinghai-Tibet Plateau, the forming stages of red soil in the tropics of South China, the tectonically stable periods in Guizhou, and the ages of weathering in other parts of the world during the Cenozoic era. That is to say, the ages of authigenic quartz dated by the fission track method are well feasible and credible.

  13. Fission track dating using sphene. ; Example of the Hanawa pluton. Sphene wo mochiita fission track ho ni yoru nendai sokutei. ; Hanawa shinsei gantai no rei

    Energy Technology Data Exchange (ETDEWEB)

    Ohira, H. (Niigata University, Niigata (Japan)); Honda, T. (Musashi Institute of Technology, Tokyo (Japan). Atomic Energy Research Laboratory)

    1992-09-05

    As for the Hanawa pluton which distributes near the boundary between Fukushima and Ibaraki Prefectures, the fission track (FT) dating was conducted by using sphene. The inside surfaces of the polished samples of sphene crystal were stuck by outside detectors and the grain-by-grain method was used to determine the age by the calibration method where a Mount Dromedary Complex sphene was used as the age standard sample. The spontaneous track density differed greatly from a sample to another sample, and even in the same sample the number of crystal grains which could be the measuring subject was limited. The FT ages determined on 5 samples were 67.4Ma for mylonite-like subfacies, 91.9 Ma and 92.5Ma for large shpene bearing subfacies, and 92.5 Ma and 93.1 Ma for fine grained quartz diorite-tonalite. Furthermore, the effect of ratio of Th content to U content on the measured age was also studied. 24 refs., 5 figs., 3 tabs.

  14. Apatite Biominerals

    Directory of Open Access Journals (Sweden)

    Christèle Combes

    2016-04-01

    Full Text Available Calcium phosphate apatites offer outstanding biological adaptability that can be attributed to their specific physico-chemical and structural properties. The aim of this review is to summarize and discuss the specific characteristics of calcium phosphate apatite biominerals in vertebrate hard tissues (bone, dentine and enamel. Firstly, the structural, elemental and chemical compositions of apatite biominerals will be summarized, followed by the presentation of the actual conception of the fine structure of synthetic and biological apatites, which is essentially based on the existence of a hydrated layer at the surface of the nanocrystals. The conditions of the formation of these biominerals and the hypothesis of the existence of apatite precursors will be discussed. Then, we will examine the evolution of apatite biominerals, especially during bone and enamel aging and also focus on the adaptability of apatite biominerals to the biological function of their related hard tissues. Finally, the diagenetic evolution of apatite fossils will be analyzed.

  15. FISSION-TRACK DATING OF A TEPHRA LAYER IN THE ALAT FORMATION OF THE DANDIERO GROUP (DANAKIL DEPRESSION, ERITREA

    Directory of Open Access Journals (Sweden)

    GIULIO BIGAZZI

    2004-12-01

    Full Text Available Attempts to date a biotite separate from a tephra layer recognized near Buia (Danakil Depression, Eritrea in the liwer part of the Homo remains – bearing Dandiero group (formerly attributed to the Danakil Formation using the 39Ar/40Ar method failed because of xenocrystic contamination. For this reason it was applied the fission-track method on glass, since no other phases datable with this technique were present. The quality of glass was very poor for fission-track dating, because of the small size of grains. In addition, after polishing only few glass shards showed useful surfaces for track counting and only 25 spontaneous tracks were counted. The determined fission-track age - 0.75 +/- 0.16 Ma - is a rejuvenated age due to the presence of a certain amount of annealing of spontaneous tracks. An attempt to apply the plateau method for correcting this apparent age failed. A corrected age of 1.3 +/- 0.3 Ma was computed using the size-correction method. In spite of its low precision, this fission-track age represents a significant result, since it corroborates the attribution to Jaramillo Subchron of the normal magnetozone near the base of which the tephra is located. 

  16. Post-emplacement kinematics and exhumation history of the Almora klippe of the Kumaun-Garhwal Himalaya, NW India: revealed by fission track thermochronology

    Science.gov (United States)

    Singh, Paramjeet; Patel, R. C.

    2016-11-01

    Tectonically transported crystalline thrust sheet over the Lesser Himalayan meta-sedimentary zone along the Main Central Thrust (MCT) is represented by Almora, Baijnath, Askot and Chiplakot crystalline klippen. The Almora-Dadeldhura klippe in the Kumaun-Garhwal and western Nepal Himalaya is the witness and largest representative of these crystalline klippen, south of MCT. Here, we investigate the post-emplacement kinematics and exhumation history of the Almora klippe. The newly derived zircon fission track (ZFT) ages combined with published apatite fission track (AFT), 40Ar-39Ar ages from the Almora-Dadeldhura klippe and Ramgarh thrust sheet to quantify the temporal variation in cooling ages and exhumation rates. Using 1-D numerical modelling approach, we calculate the transient exhumation rates with respect to different time intervals. New ZFT cooling ages along 50-km-long orogeny perpendicular transect across the Almora klippe range between 13.4 ± 0.6 and 21.4 ± 0.9 Ma. Published AFT ages and 40Ar-39Ar ages from the Almora-Dadeldhura klippe range 3.7 ± 0.8-13.2 ± 2.7 and 18.20-25.69 Ma, respectively. AFT ages reported from Ramgarh thrust sheet range 6.3 ± 0.8-7.2 ± 1.0 Ma in Kumaun region and 10.3 ± 0.5-14.4 ± 2.2 Ma in western Nepal. The linear age trend along with youngest ZFT age ( 14 Ma) close to the North Almora Thrust (NAT) in its hanging wall suggests rapid uplift close to the NAT due to its reactivation as back thrust. The transient exhumation rates of Almora klippe agree that the erosion rate was rapid (0.58 mma-1) close to the NAT in its hanging wall and relatively slow (0.31 mma-1) close to the SAT in its hanging wall during 15-11 Ma. We interpret that the fission track ages and transient exhumation rate pattern of crystalline klippen show a dynamic coupling between tectonic and erosion processes in the Kumaun-Garhwal Himalaya. However, the tectonic processes play the major role in controlling the exhumation pattern.

  17. FISSION-TRACK DATING OF A TEPHRA LAYER IN THE ALAT FORMATION OF THE DANDIERO GROUP (DANAKIL DEPRESSION, ERITREA)

    OpenAIRE

    2004-01-01

    Attempts to date a biotite separate from a tephra layer recognized near Buia (Danakil Depression, Eritrea) in the liwer part of the Homo remains – bearing Dandiero group (formerly attributed to the Danakil Formation) using the 39Ar/40Ar method failed because of xenocrystic contamination. For this reason it was applied the fission-track method on glass, since no other phases datable with this technique were present. The quality of glass was very poor for fission-track dating, because of the sm...

  18. Thermotectonic history of Sulu UHP metamorphic rock:Apatite fission track constraints from MH and PP2 of CCSD%苏鲁超高压变质岩的构造热历史:中国大陆科学钻探工程(CCSD)主孔(MH)和先导孔(PP2)的磷灰石裂变径迹约束

    Institute of Scientific and Technical Information of China (English)

    刘顺生; GLASMACHER Ulrich; 许志琴; WEBER Ursula; WAGNER Günther; JONCKHEERE Raymond; 殷秀兰

    2009-01-01

    本文包括中国大陆科学钻(CCSD)主孔(MH)0~5000m和先导孔(PP2)0~1000m的磷灰石裂变径迹分折结果,先导孔PP2的裂变径迹表现年龄变化范围为79.5±5.1~50.4±6.2Ma,主孔的裂变径迹表观年龄变化范围为98.6±17.0~2.9±2.0Ma.主孔在4200m以下,磷灰石样品中实际上已不存在自发裂变径迹,表明裂变径迹时钟已经"置零".实验资料表明,裂变径迹表观年龄值随样品深度的增加而逐渐减少,直到一定深度,即达到磷灰石的裂变径迹封闭温度(~120℃)以后,年龄值为零.根据主孔0~2000m和先导孔0~1000m的裂变径迹年龄剖面,作为一级近似,计算出超高压变质岩体在90~30Ma期间,平均隆升速度为~35m/Ma.对主孔测定了9个样品的约束径迹(Confined track)长度,样品约束径迹平均长度的变化范围约为13.1~7.4μm,总的变化趋势是:约束径迹平均长度随样品深度的增加而逐渐减少.样品的约束径迹长度分布都具有双峰型特征.根据裂变径迹年龄和约束径迹长度的资料,应用计算机模拟得到了样品的时间-温度(t-T)轨迹.结果表明,岩体从早白垩世(~120Ma)快速冷却以后,在晚白垩世和始新世又经历了两次加热作用,始新世末岩体所达到的温度大约是80℃,随后岩体则一直上升和缓慢冷却到现今所处的位置.在最后~30Ma岩体的平均隆升速度为~53m/Ma.

  19. Cenozoic tectonics in the Buruanga Peninsula, Panay Island, Central Philippines, as constrained by U-Pb, 40Ar/39Ar and fission track thermochronometers

    Science.gov (United States)

    Walia, M.; Yang, T. F.; Knittel, U.; Liu, T.-K.; Lo, C.-H.; Chung, S.-L.; Teng, L. S.; Dimalanta, C. B.; Yumul, G. P.; Yuan, W. M.

    2013-01-01

    Buruanga Peninsula forms the westernmost part of Panay Island, Central Philippines and is a part of the Palawan Continental Terrane (PCT), which was formerly attached to south-eastern China. It acted as the leading edge of the continental fragment and collided with the Philippine Mobile Belt (PMB) followed by convergence beneath the latter. Dating of the collision is crucial for understanding the evolution of the archipelago. Samples collected from Buruanga Peninsula were dated using U-Pb, 40Ar/39Ar and fission track dating (FTD) techniques to constrain the timing of the tectonic events related to the collision of the PMB with the PCT. These techniques have enabled us to obtain ages over a range of closure temperatures from about 700 °C to about 110 °C. Paleoproterozoic and Permian zircon U-Pb ages from Saboncogon Formation emphasize derivation of the western part of Buruanga Peninsula from SE China; zircon and apatite fission track ages of 51 Ma and 16 Ma, respectively, constrain the exhumation of this formation. The age data suggest tectonic events at ~ 14 Ma, ~ 11-12 Ma and about 7-8 Ma following intrusive activity at about 18 Ma. Uplift and exhumation at ~ 14 Ma are thought to be the result of subduction of low-density crustal rocks, at 11 Ma to be the result of isostatic uplift as a consequence of crustal thickening and at ~ 8 Ma to be due to the isostatic re-equilibration of the sediments overlying the former suture. Hence, collision is constrained to have started at about 14-15 Ma and to have ended before 8 Ma. Multi-element patterns of the 18 Ma Patria-Diorite from Buruanga Peninsula show enrichment in LILE (Rb, Sr, and K) and LREE and depletion in HFSE elements (Ti, Nb, and Ta) similar to those from Luzon volcanics and the volcanic rocks of Negros Island. These arc-signatures indicate a subduction related environment for the emplacement of this intrusive body and show that the diorite belongs to the PMB. The age constraints of the present study neither

  20. Exhumation history of the NW Indian Himalaya revealed by fission track and 40Ar/39Ar ages

    Science.gov (United States)

    Schlup, M.; Steck, A.; Carter, A.; Cosca, M.; Epard, J.-L.; Hunziker, J.

    2011-01-01

    New fission track and Ar/Ar geochronological data provide time constraints on the exhumation history of the Himalayan nappes in the Mandi (Beas valley) - Tso Morari transect of the NW Indian Himalaya. Results from this and previous studies suggest that the SW-directed North Himalayan nappes were emplaced by detachment from the underthrusted upper Indian crust by 55. Ma and metamorphosed by ca. 48-40. Ma. The nappe stack was subsequently exhumed to shallow upper crustal depths (Elsevier Ltd.

  1. Exhumation history of the NW Indian Himalaya revealed by fission track and 40Ar/39Ar ages

    Science.gov (United States)

    Schlup, Micha; Steck, Albrecht; Carter, Andrew; Cosca, Michael; Epard, Jean-Luc; Hunziker, Johannes

    2011-01-01

    New fission track and Ar/Ar geochronological data provide time constraints on the exhumation history of the Himalayan nappes in the Mandi (Beas valley) — Tso Morari transect of the NW Indian Himalaya. Results from this and previous studies suggest that the SW-directed North Himalayan nappes were emplaced by detachment from the underthrusted upper Indian crust by 55 Ma and metamorphosed by ca. 48–40 Ma. The nappe stack was subsequently exhumed to shallow upper crustal depths (

  2. First fission-track dating of zircons from Mesozoic complexes of the Crimea

    Science.gov (United States)

    Solov'ev, A. V.; Rogov, M. A.

    2010-06-01

    The fission-track dating of detrital zircon from Mesozoic terrigenous complexes of the Crimean mountains has been carried out for the first time. A young zircon population from the Tavria Group of sandstones of the Yaman ravine was dated at 220.1 ± 12.6 Ma, and the zircon population from the same deposits of the Crimea’s southern coast, at 193.6 ± 13.1, 167.1 ± 12.1, and 154.0 ± 10.2 Ma. Sandstones from the lowermost parts of the Demerdzhi Formation on Mount Yuzhnaya Demerdzhi comprise the Middle Jurassic young zircon population (169.9 ± 8.6 Ma). The age of the young zircon population from the Chenka Formation in the region of the Settlement of Observatoriya corresponds to the initial Middle Jurassic (178.9 ± 9.1 Ma). The timing of the cooling of the Mount Kastel massif was established at 149.0 ± 10.9 Ma. In all the considered cases, the age of terrigenous complexes is close to the age of enclosed zircons. Volcanic and/or magmatic rocks that formed synchronously with accumulation of terrigenous complexes in the sedimentary basin are likely to have been sources of zircons. Hence, the data obtained allow the timing of the Triassic-Jurassic magmatism in the Crimean mountains to be refined and three stages of magmatism to be distinguished: Late Triassic (Carnian?), poorly expressed Early Jurassic, and Middle Jurassic (Aalenian-Bathonian).

  3. Long-Term Landscape Evolution of the Northparkes Region of the Lachlan Fold Belt, Australia: Constraints from Fission Track and Paleomagnetic Data.

    Science.gov (United States)

    O'Sullivan; Gibson; Kohn; Pillans; Pain

    2000-01-01

    Apatite fission track thermochronology (AFTT) and paleomagnetic (PM) results have been used to constrain the Late Paleozoic to Cenozoic landscape evolution of the Lachlan Fold Belt (LFB) around the Northparkes copper-gold deposit in east-central New South Wales. The present-day landscape of this region of the LFB is relatively flat with little expression of the underlying rock and has previously been interpreted to indicate long-term stability of the region since the end of LFB orogenesis in the Early Carboniferous. This was presumably borne out by PM analyses from thick weathered horizons within open pits at the mine, which suggested that significant periods of weathering, and hence relative landscape stability, prevailed during the Early to middle Carboniferous and at some time during the Cenozoic. Results from AFTT analyses, however, indicate that the region must have experienced significant episodes of cooling/denudation during the mid-Permian to mid-Triassic and during the early Cenozoic, as well as episodes of heating/burial during the Late Carboniferous to mid-Permian and during the late Mesozoic. When combined, the AFTT and PM results are in fact consistent and indicate that since the late Paleozoic the landscape of the LFB around the Northparkes deposit has evolved through multiple episodes of denudation and deposition as well as periods of relative stability during which the thick weathering horizons formed. Together these results establish a complementary chronological framework that constrains the Late Palaeozoic to Cenozoic landscape evolution of the Northparkes region and highlights the importance of using dual data sets in elucidating the long-term landscape evolution of similar "stable" terranes.

  4. Fission-track dating of South American natural glasses: an overview

    Energy Technology Data Exchange (ETDEWEB)

    Bigazzi, G. [Istituto di Geoscienze e Georisorse, C.N.R., Via G. Moruzzi, 1, 56124 Pisa (Italy)]. E-mail: g.bigazzi@igg.cnr.it; Hadler Neto, J.C. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, UNICAMP, 13083-970 Campinas SP (Brazil); Iunes, P.J. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, UNICAMP, 13083-970 Campinas SP (Brazil); Osorio Araya, A.M. [Departamento de Fisica, Quimica e Biologia, Universidade do Estado de Sao Paulo, UNESP, 19060-900 Presidente Prudente SP (Brazil)

    2005-12-01

    Although many glass-bearing horizons can be found in South American volcanic complexes or sedimentary series, only a relatively few tephra and obsidian-bearing volcanic fields have been studied using the fission-track (FT) dating method. Among them, the volcanics located in the Sierra de Guamani (east of Quito, Ecuador) were studied by several authors. Based upon their ages, obsidians group into three clusters: (1) very young obsidians, {approx}0.2Ma old (2) intermediate-age obsidians, {approx}0.4-{approx}0.8Ma old, and (3) older obsidians, {approx}1.4-{approx}1.6Ma old. The FT method is also an efficient alternative technique for identification of the sources of prehistoric obsidian artefacts. Provenance studies carried out in South America have shown that the Sierra de Guamani obsidian occurrences were important sources of raw material for tool making during pre-Columbian times. Glasses originated from these sources were identified in sites distributed over relatively wide areas of Ecuador and Colombia. Only a few systematic studies on obsidians in other sectors were carried out. Nevertheless, very singular glasses have been recognised in South America, such as Macusanite (Peru) and obsidian Quiron (Argentina), which are being proposed as additional reference materials for FT dating. Analyses of tephra beds interstratified with sedimentary deposits revealed the performance of FT dating in tephrochronological studies. A remarkable example is the famous deposit outcropping at Farola Monte Hermoso, near Bahia Blanca (Buenos Aires Province), described for the first time by the middle of the 19th century by Charles Darwin. Considering the large number of volcanic glasses that were recognised in volcanic complexes and in sedimentary series, South America is a very promising region for the application of FT dating. The examples given above show that this technique may yield important results in different disciplinary fields.

  5. Ultrasensitive detection and dose reconstruction for plutonium-239 through fission track analysis of urine

    Science.gov (United States)

    Krahenbuhl, Melinda Pearl

    1998-12-01

    This dissertation addresses a number of deficiencies in currently used Fission Track Analysis (FTA) methodology and introduces improvements to make FTA a more reliable research tool. The refined methodology, described herein, includes a chemically-induced precipitation phase followed by anion exchange chromatography and employs a chemical tracer, Plutonium236 (Pu236). An inverse correlation between Pu recovery and sample volume has been established, and tests confirm that larger sample volumes do not result in higher accuracy or lower detection limits. Subsequently, the optimal sample volume is determined to be approximately 2 liters and the detection limit for this volume is established at 2.8 muBq/L (76 aCi/L). In comparison, the detection limits of two alternate methodologies are 2 muBq (at Brookhaven National Lab) and 3.2 muBq (at the University Hospital in Lund, Sweden). A comparative review evaluates the strengths and weaknesses of these methodologies by comparing pivotal aspects of each laboratory's process. The obvious strength of FTA is the low detection limit for fissile materials. The greatest weakness is the lack of independent confirmation for the results of the three respective methodologies. Additionally, each laboratory's unique nomenclature has made comparison and evaluation problematic and has lead to occasional misinterpretation of numeric data. Addressing the scientific and engineering community's lack of confidence in FTA will require more complete disclosure of techniques and protocols, including documentation of experimental failures. In experiments detailed in this dissertation, the refined FTA methodology was used to determine the Pu236 concentration in urine for two unique populations, radiation workers and the general population. The results of this analysis were used to predict dose according to several different interpretations of the ICRP recommendations. These predictions focused on the liver, lung and skeletal systems. Predicted

  6. Measurement of the energy spectrum of {sup 252}Cf fission fragments using nuclear track detectors and digital image processing

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa, G.; Golzarri, J. I. [UNAM, Instituto de Fisica, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Castano, V. M. [UNAM, Centro de Fisica Aplicada y Tecnologia Avanzada, Boulevard Juriquilla 3001, Santiago de Queretaro, 76230 Queretaro (Mexico); Gaso, I. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico); Mena, M.; Segovia, N. [UNAM, Instituto de Geofisica, Circuito de la Investigacion Cientifica, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

    2010-02-15

    The energy spectrum of {sup 252}Cf fission fragments was measured using nuclear track detectors and digital image analysis system. The detection material was fused silica glass. The detectors were chemically etched in an 8% HF solution. After experimenting with various etching time, it was found that the best resolution of the track diameter distribution was obtained after 30 minutes of etching. Both Gaussian and Lorentzian curves were fit to the track diameter distribution histograms and used to determine the basic parameters of the distribution of the light (N{sub L}) and heavy (N{sub H}) formed peaks and the minimum of the central valley (N{sub V}). Advantages of the method presented here include the fully-automated analysis process, the low cost of the nuclear track detectors and the simplicity of the nuclear track method. The distribution resolution obtained by this method is comparable with the resolution obtained by electronic analysis devices. The descriptive variables calculated were very close to those obtained by other methods based on the use of semiconductor detectors. (Author)

  7. Evolution of the Latir volcanic field, Northern New Mexico, and its relation to the Rio Grande Rift, as indicated by potassium-argon and fission track dating

    Science.gov (United States)

    Lipman, Peter W.; Mehnert, Harald H.; Naeser, Charles W.

    1986-05-01

    Remnants of the Latir volcanic field and cogenetic plutonic rocks are exceptionally exposed along the east margin of the present-day Rio Grande rift by topographic and structural relief in the Sangre de Cristo Mountains of northern New Mexico. Evolution of the magmatic system associated with the Latir field, which culminated in eruption of a regional ash flow sheet (the Amalia Tuff) and collapse of the Questa caldera 26 m.y. ago, has been documented by 74 new potassium-argon (K-Ar) and fission track (F-T) ages. The bulk of the precaldera volcanism, ash flow eruptions and caldera formation, and initial crystallization of the associated shallow granitic batholith took place between 28 and 25 Ma; economically important molybdenum mineralization is related to smaller granitic intrusions along the south margin of the Questa caldera at about 23 Ma. Interpretation of the radiogenic ages within this relatively restricted time span is complicated by widespread thermal resetting of earlier parts of the igneous sequence by later intrusions. Many samples yielded discordant ages for different mineral phases. Thermal blocking temperatures decrease in the order: K-Ar sanidine > K-Ar biotite > F-T zircon ≫ F-T apatite. The F-T results are especially useful indicators of cooling and uplift rates. Upper portions of the subvolcanic batholith, that underlay the Questa caldera, cooled to about 100°C within about a million years of emplacement; uplift of the batholith increases to the south along this segment of the Sangre de Cristo Mountains. Activity in the Latir volcanic field was concurrent with southwest directed extension along the early Rio Grande rift zone in northern New Mexico and southern Colorado. The geometry of this early rifting is compatible with interpretation as back arc extension related to a subduction system dipping gently beneath the cordilleran region of the American plate. The Latir field lies at the southern end of a southward migrating Tertiary magmatic

  8. Dating by fission track method: study of neutron dosimetry with natural uranium thin films; Datacao com o metodo dos tracos de fissao: estudo da dosimetria de neutrons com filmes finos de uranio natural

    Energy Technology Data Exchange (ETDEWEB)

    Iunes, P.J.

    1990-06-01

    Fission track dating is described, focalizing the problem of the decay constant for spontaneous fission of {sup 238} U and the use of neutron dosimetry in fission track analysis. Experimental procedures using thin films of natural uranium as neutron dosimeters and its results are presented. The author shows a intercomparison between different thin films and between the dosimetry with thin film and other dosimetries. (M.V.M.). 52 refs, 12 figs, 9 tabs.

  9. Post 5Ma thrusting in the Northern Alpine Foreland Basin - insights from structural geology and new (U-Th)/He and Fission Track data

    Science.gov (United States)

    von Hagke, Christoph; Cederbom, Charlotte; Lindow, Julia; Oncken, Onno; Schlunegger, Fritz

    2010-05-01

    Several hypotheses for the driving mechanism(s) behind late Neogene erosion in the Alpine region have been argued for in the past, in particular climate, tectonic and geodynamic forcing. The aim of this study, which is part of the ThermoEurope initiative, is to investigate the significance of Pliocene tectonic forcing on the thrusted part of the North Alpine Foreland Basin (NAFB). We apply thermochronology and structural geology to constrain the timing, location and magnitude of tectonic reactivation and erosion in the thrusted part of the basin and the adjacent units. Kilometre-scale erosion and thrust reactivation in the NAFB during the Pliocene is argued for based on apatite fission-track (AFT) data from the Swiss part of the basin (Cederbom. et al., 2004; Cederbom et al., submitted). A pilot (U/Th)-He study, that was carried out in the Rigi area, in the thrusted part of the Molasse Basin partly confirms the AFT results (Lindow et al, 2009). Based on these studies several suitable horizontal and complementary vertical profiles, transecting the Swiss, Austrian and German part of the basin have been chosen for further investigations. Dense sampling for (U-Th)/He and FT dating has been combined with structural investigations. Additional to the first data set, so far 47 FT ages and 75 single grain (U-Th)/He ages have been produced. Here we present data from the Entlebuch and the Rigi profiles, which are the two westernmost horizontal transects. Both are crossing the triangle zone between the thrusted Subalpine Molasse and the flat-lying Plateau Molasse. Most of the ages are considerably younger than their depositional age. Samples located south of the triangle zone have been deposited between 35 and 25 Ma but have cooling ages between 3 and 15 Ma. The ages of the samples in the Plateau Molasse in contrast have been deposited between 25 and 17 Ma and show ages between 21 and 5 Ma. In the triangle zone itself a jump to older ages can be observed. First, the data set

  10. $\\bar{p}$-Induced Fission Studies with Plastic Track Detectors Using 4$\\pi$-Geometry

    CERN Multimedia

    2002-01-01

    % EMU20 \\\\ \\\\ The annihilation of a stopped antiproton on the surface of a target nucleus produces on the average five pions with a mean energy of 230~MeV. The high excitation of the nuclei with low angular momentum transfer can also be achieved by direct pion-nucleus interactions. The fission probabilities of highly excited nuclei can be explained on the basis of high energy limit of statistical theory. Previously the binary fission and higher multiplicity break-up of various nuclei caused by the absorption of pions has been studied by our group. The mechanism of nuclear excitation may still be the same when an antiproton annihilates in a nucleus and produces pions. It would be interesting to see whether the $\\bar{p}$ annihilation produces high enough excitation energies for nuclear phase-transition to take place. If so, then the fragmentation would overwhelm binary and ternary fission process. \\\\ \\\\The use of a highly sensitive plastic detector, CR-39, was made by our group in a number of studies involving ...

  11. 黄骅坳陷裂变径迹分析与古生代烃源岩受热演化%Fission track analysis and evolution of Paleozoic source rocks headed in Huanghua Depression

    Institute of Scientific and Technical Information of China (English)

    朱炎铭; 秦勇; 张有生; 李田忠

    2001-01-01

    烃源岩的构造-受热史是有机质成熟演化、烃源岩生烃演化的最重要控制因素. 在对磷灰石裂变径迹深入研究的基础上,探讨了黄骅坳陷古地温场的演化历史,揭示了古生代烃源岩自形成以来至少经历4期构造-热事件,导致其有机质生烃作用呈阶段性演进.%It is the most important that source rocks tectonicheated history to maturity of organic matter and controls on the hydrocarbongeneration of source rocks. Based on detailed researched of fission tracks in apatite, evolution history of paleogeothermal field in the Huanghua Depression is analysed. It reveals that the Paleozoic source rocks at least have gone through four episodes of tectonicheated evens, and led up to the hydrocarbon generation of organic matter advanced in discontinuous.

  12. Combined application of alpha-track and fission-track techniques for detection of plutonium particles in environmental samples prior to isotopic measurement using thermo-ionization mass spectrometry.

    Science.gov (United States)

    Lee, Chi-Gyu; Suzuki, Daisuke; Esaka, Fumitaka; Magara, Masaaki; Kimura, Takaumi

    2011-07-15

    The fission track technique is a sensitive detection method for particles which contain radio-nuclides like (235)U or (239)Pu. However, when the sample is a mixture of plutonium and uranium, discrimination between uranium particles and plutonium particles is difficult using this technique. In this study, we developed a method for detecting plutonium particles in a sample mixture of plutonium and uranium particles using alpha track and fission track techniques. The specific radioactivity (Bq/g) for alpha decay of plutonium is several orders of magnitude higher than that of uranium, indicating that the formation of the alpha track due to alpha decay of uranium can be disregarded under suitable conditions. While alpha tracks in addition to fission tracks were detected in a plutonium particle, only fission tracks were detected in a uranium particle, thereby making the alpha tracks an indicator for detecting particles containing plutonium. In addition, it was confirmed that there is a linear relationship between the numbers of alpha tracks produced by plutonium particles made of plutonium certified standard material and the ion intensities of the various plutonium isotopes measured by thermo-ionization mass spectrometry. Using this correlation, the accuracy in isotope ratios, signal intensity and measurement errors is presumable from the number of alpha tracks prior to the isotope ratio measurements by thermal ionization mass spectrometry. It is expected that this method will become an effective tool for plutonium particle analysis. The particles used in this study had sizes between 0.3 and 2.0 μm.

  13. The influence of burial heating on the (U-Th)/He system in apatite: Grand Canyon case study

    Science.gov (United States)

    Fox, Matthew; Shuster, David L.

    2014-07-01

    Thermochronological data can constrain the cooling paths of rocks exhumed through the uppermost 1-2 km of earth's crust, and have thus been pivotal in illuminating topographic development over timescales >0.1 Ma. However, in some cases, different methods have led to conflicting conclusions about timing of valley-scale exhumation. Here, we investigate the case of Western Grand Canyon, USA, where different thermochronological datasets have been interpreted to record very different timings of canyon incision (∼70 Ma versus ∼5 Ma). We present a method to assess key assumptions in these constraints and demonstrate that burial heating conditions of basement rocks in the Mesozoic can result in incomplete annealing of radiation damage in apatite. In turn, this has a dramatic effect on the temperature sensitivity of the apatite (U-Th)/He system and its ability to record post-burial exhumation. The possibility of incomplete annealing resolves the apparent conflict in time-temperature paths inferred over the last 70 Ma, although it requires temperatures during burial that are lower than predicted by apatite fission track data. A refinement of parameters that prescribe the kinetics of damage annealing and related control on 4He diffusivity in apatite would account for this discrepancy, specifically if alpha recoil damage anneals at a lower rate than fission tracks at a given temperature. These effects will be important for any application of the apatite (U-Th)/He system in geologic settings that experienced prolonged residence (>10 Ma) between 50-150 °C; the approaches developed here provide means to assess these effects.

  14. Discovery of Naturally Etched Fission Tracks and Alpha-Recoil Tracks in Submarine Glasses: Reevaluation of a Putative Biosignature for Earth and Mars

    Directory of Open Access Journals (Sweden)

    Jason E. French

    2016-01-01

    Full Text Available Over the last two decades, conspicuously “biogenic-looking” corrosion microtextures have been found to occur globally within volcanic glass of the in situ oceanic crust, ophiolites, and greenstone belts dating back to ~3.5 Ga. These so-called “tubular” and “granular” microtextures are widely interpreted to represent bona fide microbial trace fossils; however, possible nonbiological origins for these complex alteration microtextures have yet to be explored. Here, we reevaluate the origin of these enigmatic microtextures from a strictly nonbiological standpoint, using a case study on submarine glasses from the western North Atlantic Ocean (DSDP 418A. By combining petrographic and SEM observations of corrosion microtextures at the glass-palagonite interface, considerations of the tectonic setting, measurement of U and Th concentrations of fresh basaltic glass by ICP-MS, and theoretical modelling of the present-day distribution of radiation damage in basaltic glass caused by radioactive decay of U and Th, we reinterpret these enigmatic microtextures as the end product of the preferential corrosion/dissolution of radiation damage (alpha-recoil tracks and fission tracks in the glass by seawater, possibly combined with pressure solution etch-tunnelling. Our findings have important implications for geomicrobiology, astrobiological exploration of Mars, and understanding of the long-term breakdown of nuclear waste glass.

  15. Laboratory-Scale Bismuth Phosphate Extraction Process Simulation To Track Fate of Fission Products

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R. JEFFREY; Lindberg, Michael J.; Jones, Thomas E.; Schaef, Herbert T.; Krupka, Kenneth M.

    2007-02-28

    Recent field investigation that collected and characterized vadose zone sediments from beneath inactive liquid disposal facilities at the Hanford 200 Areas show lower than expected concentrations of a long-term risk driver, Tc-99. Therefore laboratory studies were performed to re-create one of the three processes that were used to separate the plutonium from spent fuel and that created most of the wastes disposed or currently stored in tanks at Hanford. The laboratory simulations were used to compare with current estimates based mainly on flow sheet estimates and spotty historical data. Three simulations of the bismuth phosphate precipitation process show that less that 1% of the Tc-99, Cs-135/137, Sr-90, I-129 carry down with the Pu product and thus these isotopes should have remained within the metals waste streams that after neutralization were sent to single shell tanks. Conversely, these isotopes should not be expected to be found in the first and subsequent cycle waste streams that went to cribs. Measurable quantities (~20 to 30%) of the lanthanides, yttrium, and trivalent actinides (Am and Cm) do precipitate with the Pu product, which is higher than the 10% estimate made for current inventory projections. Surprisingly, Se (added as selenate form) also shows about 10% association with the Pu/bismuth phosphate solids. We speculate that the incorporation of some Se into the bismuth phosphate precipitate is caused by selenate substitution into crystal lattice sites for the phosphate. The bulk of the U daughter product Th-234 and Np-237 daughter product Pa-233 also associate with the solids. We suspect that the Pa daughter products of U (Pa-234 and Pa-231) would also co-precipitate with the bismuth phosphate induced solids. No more than 1 % of the Sr-90 and Sb-125 should carry down with the Pu product that ultimately was purified. Thus the current scheme used to estimate where fission products end up being disposed overestimates by one order of magnitude the

  16. Fission-track dating of the punta de vacas glaciation in the Rı´o Mendoza valley, Argentina.

    Science.gov (United States)

    Espizua, L. E.; Bigazzi, G.

    Fission-track dating of three tephra samples related to mappable drifts and non-glacial sediments, including alluvium, in the Rı´o Mendoza valley, Argentina, places limiting ages on the oldest two glacial events. A tephra-layer interstratified with fan alluvium that surrounds and cuts the outermost Uspallata moraine has an age of 170,000±50,000 yr, implying that the drift predates marine oxygen isotope stage (OIS) 6. A tephra dated at 134,000±32,000 yr, that was deposited on alluvial fan sediments, underlies Punta de Vacas drift, which is inferred to equate with Isotope Stage 6. The Punta de Vacas outwash, which likely correlates with the Rı´o Colorado drift, overlies another tephra unit that dates to 260,000±150,000 yr. Although the error limits of the dates preclude definitive correlations, all three tephra units may have been deposited during an interval prior to the maximum advance of the Punta de Vacas glaciation during OIS 6 or maybe in the Stage 7 interglacial period.

  17. Use of fission track analysis technique for the determination of MicroBequerel level of 239Pu in urine samples from radiation workers handling MOX fuel.

    Science.gov (United States)

    Yadav, J R; Rao, D D; Kumar, Ranjeet; Aggarwal, S K

    2011-07-01

    Fission track analysis (FTA) technique for the determination of (239)Pu excreted through urine has been standardized using blank samples, tracer and (239)Pu spikes. Double stage anion exchange separation protocol has been applied and an average radiochemical recovery of (239)Pu of 18% was obtained. An average track registration efficiency of 11 tracks per μBq of (239)Pu, irradiated to 0.35×10(17) neutron fluence was established. Reagent blank urine samples from 11 controlled subjects were analyzed by FTA and an average of 149±14 tracks was obtained. Minimum detectable activity of 34μBqL(-1) of urine sample was obtained and will be useful for monitoring chronic exposure cases handling MOX fuel.

  18. Mesozoic - Cenozoic tectonic evolution of southwestern Tian Shan: Evidence from detrital zircon U/Pb and apatite fission track ages of the Ulugqat area, Northwest China

    NARCIS (Netherlands)

    Yang, W.; Jolivet, M.; Dupont-Nivet, G.; Guo, Z.

    2013-01-01

    The Late Tertiary tectonic and topographic evolution of the Tian Shan Range has beenwidely studied as it represents a key example of active intra-continentalmountain belts. Recent studies have shown that both the general tectonic framework of Tian Shan and some of its actual topographic features wer

  19. Fission Track Method to Date Fault Activity —As Exemplified by the Three Gorges Dam Area of the Yangtze River Valley,CHina

    Institute of Scientific and Technical Information of China (English)

    张峰; 翟鹏济; 等

    2000-01-01

    The Xiannushan and Jiuwanxi are the two major fracture belts adjacent to the Three Gorges Dam Site,ALpatites are selected from fracture clay and fracutre-cliff rock in the fracture belts and examined with the fission track dating method.Our study shows that the Xiannushan and Jiuwanxi fracture belts wer tectonically active at 0.60±0.04 Ma and 0.29±0.04Ma ago,respectively,Their ages are close to those obtained by the U-series method.

  20. Potentialities and practical limitations of absolute neutron dosimetry using thin films of uranium and thorium applied to the fission track dating

    CERN Document Server

    Bigazzi, G; Hadler-Neto, J C; Iunes, P J; Paulo, S R; Oddone, M; Osorio, A M A; Zúñiga, A G

    1999-01-01

    Neutron dosimetry using natural uranium and thorium thin films makes possible that mineral dating by the fission-track method can be accomplished, even when poor thermalized neutron facilities are employed. In this case, the contributions of the fissions of sup 2 sup 3 sup 5 U, sup 2 sup 3 sup 8 U and sup 2 sup 3 sup 2 Th induced by thermal, epithermal and fast neutrons to the population of tracks produced during irradiation are quantified through the combined use of natural uranium and thorium films. If the Th/U ratio of the sample is known, only one irradiation (where the sample and the films of uranium and thorium are present) is necessary to perform the dating. However, if that ratio is unknown, it can be determined through another irradiation where the mineral to be dated and both films are placed inside a cadmium box. Problems related with film manufacturing and calibration are discussed. Special attention is given to the utilization of thin films having very low uranium content. The problems faced sugg...

  1. 四川盆地东南缘中新生代构造隆升的裂变径迹证据%Fission track evidence for Mesozoic-Cenozoic uplifting in the southeastern margin of Sichuan basin

    Institute of Scientific and Technical Information of China (English)

    李双建; 李建明; 周雁; 沃玉进; 汪新伟

    2011-01-01

    Viewed from sedimentary records, the uplift and deformation in the southeastern margin of Sichuan basin occurred later than late Jurassic.Prior to this event, there existed a favorable petroleum geological conditions resulting in large scale hydrocarbon accumulation in this area.However, hydrocarbon accumulation was destroyed and adjusted by uplift and deformation of the sedimentary sequence.It is of great significance to determine the time limit of uplift and analyze its effect on hydrocarbon accumulation.Based on apatite fission track analysis of eight samples from different strata in the southeastern margin of Sichuan basin, the authors confirmed the Mesozoic-Cenozoic uplifting time limit and discussed its tectonic and petroleum geological significance.The apatite track lengths are distributed mostly in the single peak form, with a few in the double-peak form.The mean track length is between 10 μm and 13 μm., and standard error is between 1.5 μm and 2.5 μm.The distribution characteristics of fission tracks suggest that the samples have experienced a slow cooling process.The thermal history simulation results show that all the samples have not experienced obvious subsidence since they entered the partial annealing zone.Almost all the samples have experienced three uplift periods, i.e., fast uplift in the early period, gentle uplift in the middle period and fast uplift in the late period, with the uplift time being different in different areas.The first uplift period in the southeastern margin of Sichuan basin occurred at about 90 ~ 60 Ma, and the arrival at the margin of the basin occurred at 40~35 Ma after northward transmission.Almost all of the samples experienced fast uplift events in late Cenozoic, and the time limit of them are within 10 Ma, with most of them being younger than 5 Ma and a few of them younger than 2 Ma.From the angle of plate tectonics, the uplift of this area in Himalayan period was related to the uplift of Tibet.From the angel of

  2. Delayed fission

    Energy Technology Data Exchange (ETDEWEB)

    Hatsukawa, Yuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-07-01

    Delayed fission is a nuclear decay process that couples {beta} decay and fission. In the delayed fission process, a parent nucleus undergoes {beta} decay and thereby populates excited states in the daughter. If these states are of energies comparable to or greater than the fission barrier of the daughter, then fission may compete with other decay modes of the excited states in the daughter. In this paper, mechanism and some experiments of the delayed fission will be discussed. (author)

  3. Development of image capture system of fission tracks in plastic detectors; Desenvolvimento de sistema de captura de imagens de tracos nucleares em detectores plasticos

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Elder M. de; Melo, Vicente P. [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil). Dept. de Protecao Radiologica Ambiental

    2001-07-01

    Plastic detectors are appropriate for detection and registration of alpha particles and fission products. The interaction of these particles with the detector damage its molecular structure, leading to a latent track (visible only under an electronic microscope) with diameter in the nanometer magnitude order. There are two etching methods: the conventional and the electrochemistry one. In the conventional etching the usual conditions is to attack with NaOH 6M, producing a track of average diameter of 3 {mu} m. In the electrochemistry etching the diameter is {approx} 150 {mu}m. The aim of this work is to show the functionality of the scanner for the acquisition of these images in conditions of electrochemistry etching. We employed the following attack solution: KOH/C{sub 2}H{sub 5}OH 15% p/v, pre-etching of 30 minutes, etching with tension of 1000 V, frequency of 100 Hz, during an hour and another stage of an hour, with frequency of 8 kHz. The images were acquired with optical resolution of 400 dpi and amplification of 300%, what allows printing in paper or counting and observation of the tracks in the screen. Results have shown that the replacement of the conventional system by a scanner computer device can be performed without loss of reliability of confidence in the tracks measurement and observation. (author)

  4. Comparisons of fission track age-determination and radioactivation analysis among radiation fields. Characteristic values for pneumatic tube, JRR-3M PN2

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Tatsuro [Kagoshima Univ. (Japan). Faculty of Education; Tomura, Kenji

    1996-01-01

    It is necessary for Fission track age determination and radioactivation analysis to define the energy spectrum of a reactor neutron as the basis for calculating the nuclear reaction rate. This study was made aiming to define the spectrum for PN2 pneumatic tube of No. 3 plant of Japan Atomic Energy Research Institute (JAERI). Characteristics such as conventional flux, cross reaction, neutron temperature and integral fast flux were examined for 3 facilities; JRR-2, JRR-4 and JRR-3M. And the neutron spectrum for each facility was estimated based on the assumptions; Maxwell distribution for thermal neutrons, 1/E for intermediate neutrons and Watt`s formula for fast neutrons. The present results showed that the spectrum for JRR-3M, PN2 was discontinuous in the range from the intermediate to the fast neutron, whereas those for other facilities were found considerably improved. (M.N.)

  5. Hanford Apatite Treatability Test Report Errata: Apatite Mass Loading Calculation

    Energy Technology Data Exchange (ETDEWEB)

    Szecsody, James E.; Vermeul, Vincent R.; Williams, Mark D.; Truex, Michael J.

    2014-05-19

    The objective of this errata report is to document an error in the apatite loading (i.e., treatment capacity) estimate reported in previous apatite treatability test reports and provide additional calculation details for estimating apatite loading and barrier longevity. The apatite treatability test final report (PNNL-19572; Vermeul et al. 2010) documents the results of the first field-scale evaluation of the injectable apatite PRB technology. The apatite loading value in units of milligram-apatite per gram-sediment is incorrect in this and some other previous reports. The apatite loading in units of milligram phosphate per gram-sediment, however, is correct, and this is the unit used for comparison to field core sample measurements.

  6. Crystallization of Apatites

    DEFF Research Database (Denmark)

    Ibsen, Casper Jon Steenberg

    2014-01-01

    . Et af disse er mineralet hydroxylapatit (Ca5(PO4)3(OH)), som udgør den uorganiske del af vores knogler og tænder. Hovedbestanddelen af denne afhandling omhandler netop dette mineral. Som modelsystem på biomineralisering syntetiserer vi apatit nanokrystaller, der minder om dem, der findes i vores...... kraftigt påvirker stabiliteten af det amorfe forstadie. Derudover viser vi, at selve sammensætningen af den amorfe fase samt valget af mod-ion har ikke-trivielle konsekvenser for krystallisationsprocessen. Alt i alt giver disse resultater indsigt i de dynamiske processer, der ligger bag dannelse af apatit...

  7. Application of the dating by fission tracks to determine thermicity of basins within petroleum potentialities: example of Sbaa and Ahnet-North basins located in Western Saharan platform, Algeria; Application de la datation par traces de fission a l'analyse de la thermicite de bassins a potentialites petrolieres: exemple de la cuvette de Sbaa et du bassin de l'Ahnet-Nord (plate-forme saharienne occidentale, Algerie)

    Energy Technology Data Exchange (ETDEWEB)

    Akkouche, M

    2007-05-15

    The interpretation of old fundamental research works and the results obtained by this study based on: the analysis of apatite fission tracks (AFT), the burial evolution curves and the sequential analysis of outcrop section, as well as the curves of signal of gamma ray (GR) analysis from drilling wells, allow to precise that the geodynamic evolution of the studied Algerian sedimentary basins (Ahnet and Sbaa) have been occurred principally in the Paleozoic era. The analysis of burial evolution curves shows that during the Paleozoic period, the sedimentation is controlled by the tectonic subsidence, particularly at the end of Carboniferous in the favor of Ougarta folding. The curves indicate an uplift from the Permian to middle Jurassic, expressed by an important erosion of sedimentary series and is considered as a response of thermal convection of the Saharan platform followed by thermal subsidence. This can be explained by the halt motion of rift extension caused by the opening of the Atlantic Ocean. To bring the sequential analysis out, it appears that Ahnet and Sbaa basins present contrasted stratigraphic recordings, so much in time than in space, indicated the different effects from subsidence and erosions according to their sectors. In thermal point of view, temperatures are still moderate in Sbaa depression and favorite the preservation of organic matter and might generate hydrocarbons until now. However, these conditions are not similar to ones in the case of Ahnet basin. In the North part of Ahnet basin (MRS-1, MSL-1), the ages are around 50 Ma, attested that sedimentary layers have been sustained a post-Hercynian thermal phase. This phase could be estimated probably more than 100 C. This is also produced during the regional extension of the Triassic-Jurassic rifting. This episode could also be responsible of disappearance (total?) of pre-existence fission tracks in the Devonian layers of the well MSR-1, which exhibits at the depth 505 m under the Hercynian

  8. Modelling of low-temperature exhumation rate in Dabie Mountain based on (U-Th)/He and fission-track thermochronological data

    Institute of Scientific and Technical Information of China (English)

    DING Ruxin; ZHOU Zuyi; XU Changhai; LIU Yuzhu; CHENG Hao; XU Fei

    2006-01-01

    While the high-temperature exhumation process in the Dabie Mountain has been well documented, the low-temperature exhumation of this area since Cretaceous, especially since Late Cretaceous, is relatively less studied. Low-temperature thermochronology provides one of the important approaches to solve this problem. Based on the data of fission track and (U-Th)/He analysis of apaptites and zircons from the granitoid and metamorphic rocks in the Dabie Mountain, this paper applies Mancktelow's and Braun's methods to estimating the exhumation rates and to drawing the regional differential exhumation pattern since Cretaceous, especially since Late Cretaceous by taking into consideration factors such as heat transport, heat advection, topography and heat production,which could influence geothermal field in the shallow crust. Since Cretaceous, the exhumation rate (0.08-0.10 km/Ma) in the region around Tiantangzhai and in the south of Tanlu fault zone is larger than the rate (0.04-0.07 km/Ma) in other areas of the Dabie Mountain. The regional differential exhumation pattern might be related to the push-up effect caused by differential strike-slip movement along NNE-trending faults.

  9. Paleocene-Early Eocene uplift of the Altyn Tagh Mountain: Evidence from detrital zircon fission track analysis and seismic sections in the northwestern Qaidam basin

    Science.gov (United States)

    Wang, Yadong; Zheng, Jianjing; Zheng, Youwei; Liu, Xingwang; Sun, Guoqiang

    2015-12-01

    Most existing tectonic models suggest that the deformation and uplift of the northern Tibetan Plateau is the latest crustal response to the collision of the India Plate and Eurasian Plate. The tectonic evolution of Altyn Tagh Mountain (hereafter called simply the "Altyn Tagh"), on the northern margin of the Tibetan Plateau, has attracted considerable scientific attention. In this study, we use fission track age dates of detrital zircons from the northwestern Qaidam basin together with sedimentary observations to understand more fully the Cenozoic tectonic uplift of the Altyn Tagh. Detrital zircons from five borehole samples distributed in different folds in the northwestern Qaidam basin yielded ages mainly ranging from 88.5 to 49.2 Ma, older than their sedimentary deposition ages (43.8-22 Ma). The binomial distribution in grain age fitted peaks was generally dominated by one young peak, P1, which varied from 73.6 to 47.2 Ma. A thinning of the Cenozoic Lulehe Formation (53.5-43.8 Ma) stretched from the inner Qaidam basin to the slopes of the Altyn Tagh in the seismic sections of the northwestern Qaidam basin. Based on magnetostratigraphic dating, there was a hiatus in sedimentation in the Qaidam basin between 65 Ma and 54 Ma; this was confirmed by seismic profiles and borehole data, which show an unconformity between the Mesozoic Quanyagou Formation and the Lulehe Formation. Combined with an analysis of provenance, the detrital zircon young peak age and the sedimentary record revealed that the most significant regional uplift of the Altyn Tagh occurred during the Paleogene-Early Eocene, almost coinciding with the collision of the Indian and Eurasian plates between 65 Ma and 44 Ma.

  10. Late Eocene to Early Miocene Andean uplift inferred from detrital zircon fission track and U-Pb dating of Cenozoic forearc sediments (15-18°S)

    Science.gov (United States)

    Decou, A.; von Eynatten, H.; Dunkl, I.; Frei, D.; Wörner, G.

    2013-08-01

    Timing, amount, and mechanisms of uplift in the Central Andes have been a matter of debate in the last decade. Our study is based on the Cenozoic Moquegua Group deposited in the forearc basin between the Western Cordillera and the Coastal Cordillera in southern Peru from ˜50 to ˜4 Ma. The Moquegua Group consists mainly of mud-flat to fluvial siliciclastic sediments with upsection increasing grain size and volcanic intercalations. Detrital zircon U-Pb dating and fission track thermochronology allow us to refine previous sediment provenance models and to constrain the timing of Late Eocene to Early Miocene Andean uplift. Uplift-related provenance and facies changes started around 35 Ma and thus predate major voluminous ignimbrite eruptions that started at ˜25 by up to 10 Ma. Therefore magmatic addition to the crust cannot be an important driving factor for crustal thickening and uplift at Late Eocene to Early Oligocene time. Changes in subduction regime and the subducting plate geometry are suggested to control the formation of significant relief in the area of the future Western Cordillera which acts as an efficient large-scale drainage divide between Altiplano and forearc from at least 15.5 to 19°S already at ˜35 Ma. The model integrates the coincidence of (i) onset of provenance change no later than 35 Ma, (ii) drastic decrease in convergence rates at ˜40, (iii) a flat-subduction period at around ˜40 to ˜30 Ma leading to strong interplate coupling, and (iv) strong decrease in volcanic activity between 45 and 30 Ma.

  11. Genesis of Daba arcuate structural belt related to adjacent basement upheavals:Constraints from Fission-track and (U-Th)/He thermochronology

    Institute of Scientific and Technical Information of China (English)

    GUILLOT; Franois

    2010-01-01

    Fission-track, (U-Th)/He thermochronology, and cooling properties indicate that the southern Daba arcuate zone (SDBAZ) underwent a distinctive phase of rapid cooling in 153-100 Ma at a rate of 1.44-1.90°C/Ma. This rapid uplifting strongly contrasts with (1) the previous, rapid foreland subsidence during Early to Middle Jurassic in response to late-orogenic compression from the Qinling belt, (2) the succeeding long, slow cooling phase and relative thermal stability that occurred during the 100-45 Ma period. This rapid cooling event in the SDBAZ parallels those experienced by two adjacent upheavals of Huangling (HLUZ) and Hannan-Micang (HMUZ), with cooling rates of 2.22-3.17°C/Ma for the HLUZ in 160-126 Ma, 4.91°C/Ma for the southern HMUZ in 150-125 Ma, as well as 2.11°C/Ma for the northern HMUZ in 150-105 Ma. Comparing thermal histories among the SDBAZ, the HLUZ, the HMUZ, and the Wudang metamorphic zone (WDMZ), we infer that the Daba arcuate structural belt formed in 153-100 Ma. The combined dating data support a correlation with a low-angle arcuate south-thrusting of the Qinling orogen triggered by northward convergence of the Yangtze Craton, contemporaneously encountering rigid basement obstructions from the HLUZ and the HMUZ, respectively. Both the SDBAZ and neighboring domains additionally underwent a comparatively fast cooling and uplift since about 45 Ma.

  12. Evidence of Thermal Evolution History of Northeast Sichuan Basin (U-Th)/He Low Temperature Thermochronometry of Apatite and Zircon

    Institute of Scientific and Technical Information of China (English)

    Qin Jianzhong; Wang Jie; Qiu Nansheng

    2008-01-01

    (U-Th)/He dating is a newly developed low temperature thermochronometry,and it elaborately reflects cooling history of geologic body under low temperature.It can be applied to analyze thermal evolution of the sedimentary basin,combining with vitrinite reflectance and fission track.(U-Th)/He dating of apatite and zircon from drilling cores in Puguang (普光)-Maoba (毛坝) area and outcrops in Tongjiang (通江) area indicates that the Northeast Sichuan (四川) basin underwent great uplift and denudation during the Tertiary and the Quaternary.During the period,denudation rates changed from 74.8 to 172.5 m/Ma and denudation thickness was between 2 800 and 3 000 m,geotemperature gradually declined into the current temperature,passing through helium closure temperature of apatite.The uplift and denudation relate to new tectonic movement response in the Sichuan basin aroused by the Qinghai (青海)-Tibet plateau.Drilling samples above 4 000 m did not undergo closure temperature of zircon,but the samples nearly 4 000 m might approach closure temperature of zircon and all the samples underwent closure temperature of apatite.According to (U-Th)/He ages of zircon,it is concluded that the Northeast Sichuan basin began to uplift in the Late Jurassic.From the Late Jurassic to the Paleogene,Northeast Sichuan basin was in slow uplift and denudation,but the denudation of Puguang-Maoba area was earlier than that of Tongjiang area.(U-Th)/He ages of zircon indicate the denudation time of provenance areas.On the basis of paleodrainage characteristics,provenance transport and other related data,provenance areas of the clastic rocks are decided,which is worthy to be investigated further.

  13. Uranium-bearing francolites present in organic-rich limestones of NW Greece: a preliminary study using synchrotron radiation and fission track techniques

    DEFF Research Database (Denmark)

    Tzifas, I. T.; Glasmacher, U. A.; Misaelides, P.;

    2017-01-01

    Synchrotron radiation techniques (μ-XRF and μ-XANES) were applied to the study of organic-rich phosphatized limestones of NW Greece (Epirus). The results revealed uranium accumulation in areas of the material containing, among others, carbonate apatite (francolite) and organic matter. The UL3-edge...

  14. Thorium-uranium fission radiography

    Science.gov (United States)

    Haines, E. L.; Weiss, J. R.; Burnett, D. S.; Woolum, D. S.

    1976-01-01

    Results are described for studies designed to develop routine methods for in-situ measurement of the abundance of Th and U on a microscale in heterogeneous samples, especially rocks, using the secondary high-energy neutron flux developed when the 650 MeV proton beam of an accelerator is stopped in a 42 x 42 cm diam Cu cylinder. Irradiations were performed at three different locations in a rabbit tube in the beam stop area, and thick metal foils of Bi, Th, and natural U as well as polished silicate glasses of known U and Th contents were used as targets and were placed in contact with mica which served as a fission track detector. In many cases both bare and Cd-covered detectors were exposed. The exposed mica samples were etched in 48% HF and the fission tracks counted by conventional transmitted light microscopy. Relative fission cross sections are examined, along with absolute Th track production rates, interaction tracks, and a comparison of measured and calculated fission rates. The practicality of fast neutron radiography revealed by experiments to data is discussed primarily for Th/U measurements, and mixtures of other fissionable nuclei are briefly considered.

  15. Fission track constrain on mineralization time and tectonic events in Ganzi-Litang gold belt, Tibet Plateau%四川甘孜-理塘金成矿带成矿时代与构造活动的裂变径迹研究

    Institute of Scientific and Technical Information of China (English)

    郇伟静; 李娜; 袁万明; 龚庆杰; 张静; 王庆飞

    2013-01-01

    通过对甘孜-理塘金矿带内6个金矿区的11个磷灰石和锆石的裂变径迹数据分析,并对磷灰石数据进行热历史模拟,分析讨论了甘孜-理塘金矿带的成矿时代、构造热历史和构造事件.锆石裂变径迹结果显示金成矿时代主要为82~140Ma,属早白垩世成矿,并由南往北成矿时代具有变小的趋势,其中南段为124 ~ 140Ma,中段107Ma,北段约82Ma.磷灰石年龄亦具有同样趋势,矿石年龄为14 ~ 27Ma,围岩为88~ 95 Ma.金矿带自燕山期以来,主要经历3个演化阶段,200~ 140Ma处于退火带中,为缓慢降温期,140 ~ 30Ma为相对平缓降温阶段,30Ma以来为快速降温期.从南到北降温速率依次加快,从锆石封闭温度250℃降至磷灰石封闭温度100℃的平均速率分别为1.46℃/Ma、1.67℃/Ma和2.21℃/Ma,对应的隆升速率为48.7m/Ma、55.7m/Ma和73.7m/Ma;从100℃降至地表温度的速率为3.15℃/Ma、5℃/Ma和6.07℃/Ma,对应的隆升速率为104.9m/Ma、166.7m/Ma和202.4m/Ma.甘孜-理塘带的大规模陆内隆升主要在3Ma内,平均20℃/Ma,667m/Ma,属于快速隆升,隆升量约2km.%This paper applies fission track thermochronology to probe mineralization age for six gold deposits and reveal the evolution of geological thermal history and tectonic events in the last 200Ma in Ganzi-Litang gold belt, Tibet Plateau. The results of zircon fission track analysis suggest the main mineralization ages are about 82 ~ 140Ma, decreasing from south section to north section. The mineralization ages are 124 ~ 140Ma, 107Ma and 82Ma in the south section, the middle section and the north section respectively. The apatite fission track analysis shows the similar trend from south section to north section, in which the ore ages are about 14 ~27Ma and the wallrock ages are 88 ~95Ma. Thermal history modeling results show that three cooling stages since Yanshannian. The first stage occurred before 200 ~ 140Ma and the third stage after 30Ma. The

  16. Ternary fission

    Indian Academy of Sciences (India)

    M Balasubramaniam; K R Vijayaraghavan; C Karthikraj

    2015-09-01

    We present the ternary fission of 252Cf and 236U within a three-cluster model as well as in a level density approach. The competition between collinear and equatorial geometry is studied by calculating the ternary fragmentation potential as a function of the angle between the lines joining the stationary middle fragment and the two end fragments. The obtained results for the 16O accompanying ternary fission indicate that collinear configuration is preferred to equatorial configuration. Further, for all the possible third fragments, the potential energy surface (PES) is calculated corresponding to an arrangement in which the heaviest and the lightest fragments are considered at the end in a collinear configuration. The PES reveals several possible ternary modes including true ternary modes where the three fragments are of similar size. The complete mass distributions of Si and Ca which accompanied ternary fission of 236U is studied within a level density picture. The obtained results favour several possible ternary combinations.

  17. Fission Spectrum

    Science.gov (United States)

    Bloch, F.; Staub, H.

    1943-08-18

    Measurements of the spectrum of the fission neutrons of 25 are described, in which the energy of the neutrons is determined from the ionization produced by individual hydrogen recoils. The slow neutrons producing fission are obtained by slowing down the fast neutrons from the Be-D reaction of the Stanford cyclotron. In order to distinguish between fission neutrons and the remaining fast cyclotron neutrons both the cyclotron current and the pusle amplifier are modulated. A hollow neutron container, in which slow neutrons have a lifetime of about 2 milliseconds, avoids the use of large distances. This method results in much higher intensities than the usual modulation arrangement. The results show a continuous distribution of neutrons with a rather wide maximum at about 0.8 MV falling off to half of its maximum value at 2.0 MV. The total number of netrons is determined by comparison with the number of fission fragments. The result seems to indicate that only about 30% of the neutrons have energies below .8 MV. Various tests are described which were performed in order to rule out modification of the spectrum by inelastic scattering. Decl. May 4, 1951

  18. Isotopic evidence for trapped fissiogenic REE and nucleogenic Pu in apatite and Pb evolution at the Oklo natural reactor

    Science.gov (United States)

    Horie, Kenji; Hidaka, Hiroshi; Gauthier-Lafaye, François

    2004-01-01

    A part of the boundary layer of reactor zone 10 at the Oklo natural reactor shows a unique petrologic texture, which contains high-grade uraninite and massive apatite concretions. In order to study distribution behavior of fission products around the boundary between the reactor zone and the wall rock and to clarify the relation of migration mechanisms of fission products with geochemical factors, in-situ isotopic analyses of Nd, Sm, Gd, Pb and U in uraninite and apatite from the sample were performed by Sensitive High Resolution Ion Microprobe (SHRIMP). Sm and Gd isotopic ratios of uraninite and apatite show evidence of neutron irradiation with fluence between 4.4-6.8×10 19 n/cm 2. Judging from the isotopic anomalies of Nd and U, the apatite coexisting with the uraninite plays an important role in trapping fissiogenic LREE and nucleogenic 239Pu into the structure. Systematic Pb isotopic data from apatite, uraninite, galena and minium suggest the following chronological interpretations. The apatite formed 1.92±0.01 Ga ago and trapped fissiogenic light REE and nucleogenic 239Pu that migrated from the reactor during the criticality. The uraninite around the boundary between reactor and sandstone dissolved once 1.1˜1.2 Ga ago. Galena grains were formed by U-Pb mobilization in association with the intrusion of dolerite dyke 0.45˜0.83 Ga ago. Minium was derived from recent dissolution of galena under locally oxidizing conditions.

  19. Uplifting history of Meso-Cenozoic era in the central-southern part of Longmenshan region:Evidence from the fission-track ages%龙门山中、南段中-新生代隆升史:来自裂变径迹的证据

    Institute of Scientific and Technical Information of China (English)

    唐哲民; 郭宪璞; 乔秀夫

    2011-01-01

    Through fission track chronology method, we have analyzed apatite and zircon of the Mesozoic sequence in the central-southern Longmenshan and simulated the thermal history and got the following results: (1) the Mesozoic sequence at the Tianquan-Huaiyuan area in the central-southern Longmenshan had the strongest uplift in the Late Himalayan stage, coincident with the strong structure movement in the region. ( 2 ) For the profiles at southwestern and western Huaiyuan Town, the rapid uplift in Late Himalayan initiated from 20Ma in the west to 7 ~5Ma in the east and continued up to now, I. E. , the beginning time of the uplift became younger from west to east, which is well corresponding with the eastwards progressive thrusting of the Longmenshan orogeny. (3) Some of local uplift events occurred at 165 ~ 155Ma, 140 ~77Ma and 55 ~22Ma.%运用裂变径迹年代学方法对龙门山中、南段中生代地层内的磷灰石、锆石进行分析,并进行了热历史模拟,结果表明:①龙门山中、南段天全、怀远一带中生代地层最主要的强烈隆升阶段为喜山晚期,与该区的强烈构造运动时期相一致;②怀远镇西南侧及西侧剖面,喜山晚期强烈隆升阶段的时间自西侧的20Ma左右开始至东侧的7~5Ma开始并延续至今,开始强烈隆升的时间自西向东逐步变新;与龙门山造山带逆冲推覆作用在时空上具向东前展式渐进推覆的特点相对应;③部分地区存在163~155Ma、140~77 Ma、55~22Ma的隆升事件.

  20. New Apatite and Zircon (U-Th)/He Constraints on the Timing of Thrust-Related Exhumation in the Southern Bolivian (21˚S) Andes

    Science.gov (United States)

    Anderson, R. B.; Long, S. P.; Horton, B. K.; Calle, A.; Stockli, D. F.

    2014-12-01

    Data suggesting rapid middle Miocene uplift of the southern Altiplano prompts resolving disagreements over the geometry, magnitude, and timing of Andean deformation in southern Bolivia (21°S) in order to test geodynamic responses of the thrust belt predicted by the Cordilleran cyclicity model. New apatite and zircon (U-Th)/He data combined with published apatite fission track data (AFT), new 1:50:000-scale mapping, and in-progress drafting of a balanced cross-section provide new insight into the geometry and timing of deformation, and the timing and rates of exhumation. Mapping was focused along an east-west transect through the Subandean Zone (SAZ), Interandean Zone (IAZ), and Eastern Cordillera (EC). Regional-scale folds (~10-20 km wavelength, ~4-6 km amplitude) in the SAZ exhume rocks as deep as Carboniferous above a 10-12 km deep decollemont in Silurian rocks. In the IAZ, thinner (~1-4 km), closely-spaced thrust sheets exhume Devonian and Silurian rocks, and a regional-scale anticlinorium in the easternmost EC exhumes rocks as deep as Cambrian and Ordovician. 11 new apatite and 5 new zircon (U-Th)/He cooling ages provide timing constraints on the initiation of thrust-related exhumation. Zircon cooling ages (32.8±1.4 to 25.4±1.2 Ma) reveal initiation of exhumation in the easternmost EC as early as ~32 Ma, and an exhumed partial retention zone at the EC-IAZ boundary. Apatite ages in the IAZ range from 21.71±0.77 to 7.45±0.20 Ma, and consistently young to the east. Exhumation was previously thought to have begun in the IAZ at ~10 Ma, but our results show thrust-related exhumation as early as ~22 Ma, in agreement with published AFT data that show that deformation had propagated eastward into the IAZ by at least ~18 Ma. In the western SAZ, apatite cooling ages of 6.10±0.17 and 4.84±0.14 Ma demonstrate that thrust-related uplift and exhumation in the western SAZ had begun by at least the late Miocene. These new data show a consistent eastward propagation of

  1. Apatite fission track dating and thermal history of Qing-He Region in Altay Mountains%磷灰石裂变径迹法研究阿尔泰青河地区地质热历史

    Institute of Scientific and Technical Information of China (English)

    保增宽; 袁万明; 董金泉; 高绍凯

    2005-01-01

    对阿尔泰青河县城附近的闪长岩岩体进行了磷灰石裂变径迹研究,并探讨了该区的地质热历史.裂变径迹年龄为(78±5)-(95±5)Ma,平均径迹长度为(13.2±1.2)-(13.5±1.3)μm.热历史模拟结果表明,阿尔泰青河地区具有4阶段的热演化模式,其中115-85 Ma的快速冷却阶段反映了该地区在燕山期仍然存在着岩浆侵入活动和断裂带构造运动.

  2. THERMAL HISTORY OF CENTRAL AREA OF THE TARIM BASIN BY APATITE FISSION TRACK ANALYSIS%利用磷灰石裂变径迹研究塔里木盆地中部地区的热历史

    Institute of Scientific and Technical Information of China (English)

    李慧莉; 邱楠生; 金之钧

    2005-01-01

    利用磷灰石裂变径迹反演计算了塔里木中部地区3口井志留纪以来的热历史.研究认为,塔中地区志留纪以来的大地热流变化不大,为56~62 mW/m2.志留纪、泥盆纪大地热流较低,约为58 mW/m2;石炭纪大地热流略有增高,二叠纪时大地热流可能达到62 mW/m2;中生代期间,大地热流逐渐降低,中生代末约为57 mW/m2;新生代期间,大地热流略有增高,现今大地热流约为60 mW/m2.塔中地区的热历史与其构造演化史密切相关.

  3. A Research on Thermal Evolution History of Carboniferous in Bayanhaote Basin by Using Apatite Fission Track%应用磷灰石裂变径迹探讨巴彦浩特石炭系热演化史

    Institute of Scientific and Technical Information of China (English)

    曹新焰; 严永新; 林学庆; 李亚玉; 成新生; 周扬新

    2001-01-01

    巴彦浩特盆地石炭系磷灰石裂变径迹年龄研究分析认为,该盆地磷灰石裂变径迹退火年龄自侏罗纪以后,侏罗系再未经历高于120℃的温度,而石炭系在白垩纪末普遍达到磷灰石的最大退火温度.结合盆地地质情况,石炭系在地质历史上经历的古地温不会太高,一般没有超过120℃,所经历的最高地温时间是晚白垩世,大量有机质在这一时期进行生排烃,具有晚期成烃的特点.

  4. Thermal history of the Fangshan granodiorite intrusion, Beijing: Evidence from fission tracks of apatites and sphenes%从裂变径迹分析探讨房山岩体地质热历史

    Institute of Scientific and Technical Information of China (English)

    翟鹏济; 张峰; 赵云龙

    2003-01-01

    测定了房山岩体内部相的花岗闪长岩中磷灰石和榍石的裂变径迹年龄和磷灰石自发和诱发裂变封闭径迹长度.根据磷灰石自发裂变封闭径迹平均长度和年龄对岩体热历史进行了模拟和探讨,长度分布模拟特征和参数与实测结果基本一致.并依据磷灰石和榍石裂变径迹年龄和封闭温度探讨了岩体的冷却和上升速度.

  5. Negative Pion Induced Fission with Heavy Target Nuclei

    Institute of Scientific and Technical Information of China (English)

    G. Sher; Mukhtar A. Rana; S. Manzoor; M. I. Shahzad

    2011-01-01

    We investigate fission induced by negative pions in copper and bismuth targets using CR-39 dielectric track detectors. The target-detector assemblies in Air-geometric configuration were exposed at the AGS facility of Brookhaven National Laboratory, USA. The exposed detectors were chemically etched under appropriate etching conditions and scanned to collect data in the form of fission fragments tracks produced as a result of interaction of pions with the target nuclei. Using the track counts, the experimental fission cross sections for copper and bismuth have been measured at energies of 500, 672, 1068 and 1665 MeV and compared with the calculation using the Cascade-Exciton Model code (CEM95). The values of fission probability based on experimental fission cross-sections have been compared with the theoretically calculated values of fission probabilities obtained using the CEM95 code. Good agreement is observed between the measured and computed results.

  6. 随机占优精英裂变算法用于空中移动目标跟踪%Airborne Moving Target Tracking Based on Stochastic Dominance Elite Fission Algorithm

    Institute of Scientific and Technical Information of China (English)

    熊娟

    2013-01-01

    针对粒子群算法跟踪空中目标的缺点,提出随机占优精英裂变算法.首先对父体大权值粒子裂变,形成子代个体空间,覆盖小权值粒子;接着采用精英策略,计算个体在选择过程中被选中的概率,使大部分较优个体参与进化,用极小欧几里德距离计算拥挤距离;然后采用分布函数来确定采样数据的随机占优关系;最后给出了空中目标运动模型.实验仿真表明,滤波轨迹接近空中运动目标的轨迹,在整个观测区域内具有很好的跟踪效果,位置误差标准值小.%Considering the disadvantages of particle swarm optimization algorithm in aerial target tracking, stochastic dominance elite fission algorithm was proposed. After the fission of the parent body weight value particle, individual space was formed, which covered with small weight particle. Then, the elitist strategy was adopted for calculating the probability of an individual being selected, made the most of fine individuals participate in evolution. The crowding distance was calculated out with minimum Euclidean distance, and the distribution function was used to determine the sampling data of stochastic dominance relation. Finally, the aerial target motion model was given. The experimental simulation showed that: 1 ) the filtering trajectoriy is approximate to the aerial target moving trajectory; and 2) the tracking effect is satisfactory during the entire observation area.

  7. Ideological Fission

    DEFF Research Database (Denmark)

    Christiansen, Steen Ledet

    ; it is a materialisation of an ideological fission which attempts to excise certain ideological constructions, yet paradoxically casting them in a form that is recognizable and familiar. The monstrous metonomy which is used shows us glimpses of a horrid being, intended to vilify the attack on New York City. However......, it is a being which is reminiscent of earlier monsters - from Godzilla to The Blob. It is evident that the Cloverfield monster is a paradoxical construction which attempts to articulate fear and loathing about terrorism, but ends up trapped in an ideological dead-end maze, unable to do anything other than...

  8. Adherent apatite coating on titanium substrate using chemical deposition.

    Science.gov (United States)

    Rohanizadeh, R; LeGeros, R Z; Harsono, M; Bendavid, A

    2005-03-15

    Plasma-sprayed "HA" coatings on commercial orthopedic and dental implants consist of mixtures of calcium phosphate phases, predominantly a crystalline calcium phosphate phase, hydroxyapatite (HA) and an amorphous calcium phosphate (ACP) with varying HA/ACP ratios. Alternatives to the plasma-spray method are being explored because of some of its disadvantages. The purpose of this study was to deposit an adherent apatite coating on titanium substrate using a two-step method. First, titanium substrates were immersed in acidic solution of calcium phosphate resulting in the deposition of a monetite (CaHPO4) coating. Second, the monetite crystals were transformed to apatite by hydrolysis in NaOH solution. Composition and morphology of the initial and final coatings were identified using X-ray diffraction (XRD), Scanning Electron Microscopy, and Energy Dispersive Spectroscopy (EDS). The final coating was porous and the apatite crystals were agglomerated and followed the outline of the large monetite crystals. EDS revealed the presence of calcium and phosphorous elements on the titanium substrate after removing the coating using tensile or scratching tests. The average tensile bond of the coating was 5.2 MPa and cohesion failures were observed more frequently than adhesion failures. The coating adhesion measured using scratch test with a 200-microm-radius stylus was 13.1N. Images from the scratch tracks demonstrated that the coating materials were squashed without fracturing inside and/or at the border of the tracks until the failure point of the coating. In conclusion, this study showed the potential of a chemical deposition method for depositing a coating consisting of either monetite or apatite. This method has the advantage of producing a coating with homogenous composition on even implants of complex geometry or porosity. This method involves low temperatures and, therefore, can allow the incorporation of growth factors or biogenic molecules.

  9. Fission cross section measurements for minor actinides

    Energy Technology Data Exchange (ETDEWEB)

    Fursov, B. [IPPE, Obninsk (Russian Federation)

    1997-03-01

    The main task of this work is the measurement of fast neutron induced fission cross section for minor actinides of {sup 238}Pu, {sup 242m}Am, {sup 243,244,245,246,247,248}Cm. The task of the work is to increase the accuracy of data in MeV energy region. Basic experimental method, fissile samples, fission detectors and electronics, track detectors, alpha counting, neutron generation, fission rate measurement, corrections to the data and error analysis are presented in this paper. (author)

  10. Vertical tectonics at a continental crust-oceanic plateau plate boundary zone: Fission track thermochronology of the Sierra Nevada de Santa Marta, Colombia

    Science.gov (United States)

    Villagómez, Diego; Spikings, Richard; Mora, AndréS.; GuzmáN, Georgina; Ojeda, GermáN.; CortéS, Elizabeth; van der Lelij, Roelant

    2011-08-01

    The topographically prominent Sierra Nevada de Santa Marta forms part of a faulted block of continental crust located along the northern boundary of the South American Plate, hosts the highest elevation in the world (˜5.75 km) whose local base is at sea level, and juxtaposes oceanic plateau rocks of the Caribbean Plate. Quantification of the amount and timing of exhumation constrains interpretations of the history of the plate boundary, and the driving forces of rock uplift along the active margin. The Sierra Nevada Province of the southernmost Sierra Nevada de Santa Marta exhumed at elevated rates (≥0.2 Km/My) during 65-58 Ma in response to the collision of the Caribbean Plateau with northwestern South America. A second pulse of exhumation (≥0.32 Km/My) during 50-40 Ma was driven by underthrusting of the Caribbean Plate beneath northern South America. Subsequent exhumation at 40-25 Ma (≥0.15 Km/My) is recorded proximal to the Santa Marta-Bucaramanga Fault. More northerly regions of the Sierra Nevada Province exhumed rapidly during 26-29 Ma (˜0.7 Km/My). Further northward, the Santa Marta Province exhumed at elevated rates during 30-25 Ma and 25-16 Ma. The highest exhumation rates within the Sierra Nevada de Santa Marta progressed toward the northwest via the propagation of NW verging thrusts. Exhumation is not recorded after ˜16 Ma, which is unexpected given the high elevation and high erosive power of the climate, implying that rock and surface uplift that gave rise to the current topography was very recent (i.e., ≤1 Ma?), and there has been insufficient time to expose the fossil apatite partial annealing zone.

  11. Enhanced trigger for the NIFFTE fissionTPC in presence of high-rate alpha backgrounds

    Science.gov (United States)

    Bundgaard, Jeremy; Niffte Collaboration

    2015-10-01

    Nuclear physics and nuclear energy communities call for new, high precision measurements to improve existing fission models and design next generation reactors. The Neutron Induced Fission Fragment Tracking experiment (NIFFTE) has developed the fission Time Projection Chamber (fissionTPC) to measure neutron induced fission with unrivaled precision. The fissionTPC is annually deployed to the Weapons Neutron Research facility at Los Alamos Neutron Science Center where it operates with a neutron beam passing axially through the drift volume, irradiating heavy actinide targets to induce fission. The fissionTPC was developed at the Lawrence Livermore National Laboratory's TPC lab, where it measures spontaneous fission from radioactive sources to characterize detector response, improve performance, and evolve the design. To measure 244Cm, we've developed a fission trigger to reduce the data rate from alpha tracks while maintaining a high fission detection efficiency. In beam, alphas from 239Pu are a large background when detecting fission fragments; implementing the fission trigger will greatly reduce this background. The implementation of the cathode fission trigger in the fissionTPC will be presented along with a detailed study of its efficiency.

  12. Bioactivity of mica/apatite glass ceramics

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The bioactivity of mica/apatite glass ceramic composites, including the in vitro behavior in simulated body fluid and the histological appearance of the interface between the mica/apatite glass ceramics and the rabbit mandible defect in vivo under a dynamic condition. The results show that biological apatite layer forms on the surface of the mica/apatite glass ceramics after 1 d of immersion in the simulated body fluid, and becomes dense after 14 d. In vivo tests indicate that bone formation occurs after implantation for 14 d, and strong bonding of bone to the implant occurs after 42 d. No aseptic loosening occurs during 42 d of implantation. The finding shows that mica/apatite glass ceramics have good bioactivity and osteoconductivity for constructing bone graft, and can be promising for biomedical application.

  13. U-Pb Ages of Lunar Apatites

    Science.gov (United States)

    Vaughan, J.; Nemchin, A. A.; Pidgeon, R. T.; Meyer, Charles

    2006-01-01

    Apatite is one of the minerals that is rarely utilized in U-Pb geochronology, compared to some other U-rich accessory phases. Relatively low U concentration, commonly high proportion of common Pb and low closure temperature of U-Pb system of apatite inhibit its application as geochronological tool when other minerals such as zircon are widely available. However, zircon appear to be restricted to certain type of lunar rocks, carrying so called KREEP signature, whereas apatite (and whitlockite) is a common accessory mineral in the lunar samples. Therefore, utilizing apatite for lunar chronology may increase the pool of rocks that are available for U-Pb dating. The low stability of U-Pb systematics of apatite may also result in the resetting of the system during meteoritic bombardment, in which case apatite may provide an additional tool for the study of the impact history of the Moon. In order to investigate these possibilities, we have analysed apatites and zircons from two breccia samples collected during the Apollo 14 mission. Both samples were collected within the Fra Mauro formation, which is interpreted as a material ejected during the impact that formed the Imbrium Basin.

  14. To fission or not to fission

    CERN Document Server

    Pomorski, Krzysztof; Ivanyuk, Fedir A

    2016-01-01

    The fission-fragments mass-yield of 236U is obtained by an approximate solution of the eigenvalue problem of the collective Hamiltonian that describes the dynamics of the fission process whose degrees of freedom are: the fission (elongation), the neck and the mass-asymmetry mode. The macroscopic-microscopic method is used to evaluate the potential energy surface. The macroscopic energy part is calculated using the liquid drop model and the microscopic corrections are obtained using the Woods-Saxon single-particle levels. The four dimensional modified Cassini ovals shape parametrization is used to describe the shape of the fissioning nucleus. The mass tensor is taken within the cranking-type approximation. The final fragment mass distribution is obtained by weighting the adiabatic density distribution in the collective space with the neck-dependent fission probability. The neck degree of freedom is found to play a significant role in determining that final fragment mass distribution.

  15. Formation of Apatite in Simulated Body Fluid

    Institute of Scientific and Technical Information of China (English)

    FAN Dong-hui; XU Zheng; LI Shi-pu; YAN Yu-hua

    2002-01-01

    It is confirmed that the essential condition for glasses and glass-ceramics to bond to living bone is the formation of an apatite layer on their surfaces in the body. It is proposed that a hydrated silica formed on the surfaces of these materials in the body plays an important role in forming the surface apatite layer, which has noi been proved yet. It is shown experimentally that a pure hydrated silica gel can induce the apatite formation on its surface in a simulated body fluid when its starting pH is increased from 7.2 to 7.4.

  16. Cell Interactions within Biomimetic Apatite Microenvironments

    OpenAIRE

    Tsang, Eric

    2014-01-01

    Bioactive ceramics, such as calcium phosphate-based materials, have been studied extensively for the regeneration of bone tissue. Accelerated apatite coatings prepared from biomimetic methods is one approach that has had a history of success in both in vitro and in vivo studies for bone regeneration [1]-[4]. However, how cells interact within the apatite microenvironment remains largely unclear, despite the vast literature available today. In response, this thesis evaluates the in vitro i...

  17. Laser Ablation in situ (U-Th-Sm)/He and U-Pb Double-Dating of Apatite and Zircon: Techniques and Applications

    Science.gov (United States)

    McInnes, B.; Danišík, M.; Evans, N.; McDonald, B.; Becker, T.; Vermeesch, P.

    2015-12-01

    We present a new laser-based technique for rapid, quantitative and automated in situ microanalysis of U, Th, Sm, Pb and He for applications in geochronology, thermochronometry and geochemistry (Evans et al., 2015). This novel capability permits a detailed interrogation of the time-temperature history of rocks containing apatite, zircon and other accessory phases by providing both (U-Th-Sm)/He and U-Pb ages (+trace element analysis) on single crystals. In situ laser microanalysis offers several advantages over conventional bulk crystal methods in terms of safety, cost, productivity and spatial resolution. We developed and integrated a suite of analytical instruments including a 193 nm ArF excimer laser system (RESOlution M-50A-LR), a quadrupole ICP-MS (Agilent 7700s), an Alphachron helium mass spectrometry system and swappable flow-through and ultra-high vacuum analytical chambers. The analytical protocols include the following steps: mounting/polishing in PFA Teflon using methods similar to those adopted for fission track etching; laser He extraction and analysis using a 2 s ablation at 5 Hz and 2-3 J/cm2fluence; He pit volume measurement using atomic force microscopy, and U-Th-Sm-Pb (plus optional trace element) analysis using traditional laser ablation methods. The major analytical challenges for apatite include the low U, Th and He contents relative to zircon and the elevated common Pb content. On the other hand, apatite typically has less extreme and less complex zoning of parent isotopes (primarily U and Th). A freeware application has been developed for determining (U-Th-Sm)/He ages from the raw analytical data and Iolite software was used for U-Pb age and trace element determination. In situ double-dating has successfully replicated conventional U-Pb and (U-Th)/He age variations in xenocrystic zircon from the diamondiferous Ellendale lamproite pipe, Western Australia and increased zircon analytical throughput by a factor of 50 over conventional methods

  18. Apatite Formation: Why It May Not Work as Planned, and How to Conclusively Identify Apatite Compounds

    Directory of Open Access Journals (Sweden)

    Christophe Drouet

    2013-01-01

    Full Text Available Calcium phosphate apatites are inorganic compounds encountered in many different mineralized tissues. Bone mineral, for example, is constituted of nanocrystalline nonstoichiometric apatite, and the production of “analogs” through a variety of methods is frequently reported. In another context, the ability of solid surfaces to favor the nucleation and growth of “bone-like” apatite upon immersion in supersaturated fluids such as SFB is commonly used as one evaluation index of the “bioactivity” of such surfaces. Yet, the compounds or deposits obtained are not always thoroughly characterized, and their apatitic nature is sometimes not firmly assessed by appropriate physicochemical analyses. Of particular importance are the “actual” conditions in which the precipitation takes place. The precipitation of a white solid does not automatically indicate the formation of a “bone-like carbonate apatite layer” as is sometimes too hastily concluded: “all that glitters is not gold.” The identification of an apatite phase should be carefully demonstrated by appropriate characterization, preferably using complementary techniques. This review considers the fundamentals of calcium phosphate apatite characterization discussing several techniques: electron microscopy/EDX, XRD, FTIR/Raman spectroscopies, chemical analyses, and solid state NMR. It also underlines frequent problems that should be kept in mind when making “bone-like apatites.”

  19. A Time Projection Chamber for High Accuracy and Precision Fission Cross-Section Measurements

    Energy Technology Data Exchange (ETDEWEB)

    T. Hill; K. Jewell; M. Heffner; D. Carter; M. Cunningham; V. Riot; J. Ruz; S. Sangiorgio; B. Seilhan; L. Snyder; D. M. Asner; S. Stave; G. Tatishvili; L. Wood; R. G. Baker; J. L. Klay; R. Kudo; S. Barrett; J. King; M. Leonard; W. Loveland; L. Yao; C. Brune; S. Grimes; N. Kornilov; T. N. Massey; J. Bundgaard; D. L. Duke; U. Greife; U. Hager; E. Burgett; J. Deaven; V. Kleinrath; C. McGrath; B. Wendt; N. Hertel; D. Isenhower; N. Pickle; H. Qu; S. Sharma; R. T. Thornton; D. Tovwell; R. S. Towell; S.

    2014-09-01

    The fission Time Projection Chamber (fissionTPC) is a compact (15 cm diameter) two-chamber MICROMEGAS TPC designed to make precision cross-section measurements of neutron-induced fission. The actinide targets are placed on the central cathode and irradiated with a neutron beam that passes axially through the TPC inducing fission in the target. The 4p acceptance for fission fragments and complete charged particle track reconstruction are powerful features of the fissionTPC which will be used to measure fission cross-sections and examine the associated systematic errors. This paper provides a detailed description of the design requirements, the design solutions, and the initial performance of the fissionTPC.

  20. Thermal fission rates with temperature dependent fission barriers

    CERN Document Server

    Zhu, Yi

    2016-01-01

    \\item[Background] The fission processes of thermal excited nuclei are conventionally studied by statistical models which rely on inputs of phenomenological level densities and potential barriers. Therefore the microscopic descriptions of spontaneous fission and induced fission are very desirable for a unified understanding of various fission processes. \\item[Purpose] We propose to study the fission rates, at both low and high temperatures, with microscopically calculated temperature-dependent fission barriers and mass parameters. \\item[Methods] The fission barriers are calculated by the finite-temperature Skyrme-Hartree-Fock+BCS method. The mass parameters are calculated by the temperature-dependent cranking approximation. The thermal fission rates can be obtained by the imaginary free energy approach at all temperatures, in which fission barriers are naturally temperature dependent. The fission at low temperatures can be described mainly as a barrier-tunneling process. While the fission at high temperatures ...

  1. Microscopic modeling of mass and charge distributions in the spontaneous fission of 240Pu

    Science.gov (United States)

    Sadhukhan, Jhilam; Nazarewicz, Witold; Schunck, Nicolas

    2016-01-01

    We propose a methodology to calculate microscopically the mass and charge distributions of spontaneous fission yields. We combine the multidimensional minimization of collective action for fission with stochastic Langevin dynamics to track the relevant fission paths from the ground-state configuration up to scission. The nuclear potential energy and collective inertia governing the tunneling motion are obtained with nuclear density functional theory in the collective space of shape deformations and pairing. We obtain a quantitative agreement with experimental data and find that both the charge and mass distributions in the spontaneous fission of 240Pu are sensitive both to the dissipation in collective motion and to adiabatic fission characteristics.

  2. Fission Measurements with Dance

    Science.gov (United States)

    Jandel, M.; Bredeweg, T. A.; Fowler, M. M.; Bond, E. M.; Chadwick, M. B.; Clement, R. R.; Couture, A.; O'Donnell, J. M.; Haight, R. C.; Keksis, A. L.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Agvaanluvsan, U.; Dashdorj, D.; Macri, R. A.; Parker, W. E.; Wilk, P. A.; Wu, C. Y.; Becker, J. A.; Angell, C. T.; Tonchev, A. P.; Baker, J. D.

    2008-08-01

    Neutron capture cross section measurements on actinides are complicated by the presence of neutron-induced fission. An efficient fission tagging detector used in coincidence with the Detector for Advanced Neutron Capture Experiments (DANCE) provides a powerful tool in undertaking simultaneous measurements of (n,γ) and (n,f) cross sections. Preliminary results on 235U(n,γ) and (n,f) and 242mAm(n,f) cross sections measured with DANCE and a custom fission-tagging parallel plate avalanche counter (PPAC) are presented. Additional measurements of γ-ray cluster multiplicity distributions for neutron-induced fission of 235U and 242mAm and spontaneous fission of 252Cf are shown, as well as γ-ray energy and average γ-ray energy distributions.

  3. Structural properties of apatites from Finland studied by FTIR spectroscopy

    Directory of Open Access Journals (Sweden)

    Veiderma, M.

    1998-12-01

    Full Text Available Studies by XRD and FTIR analyses of the structure of Sokli and Siilinjärvi apatites and a comparison with the Kola and Kovdor apatites are presented. In the structure of apatites from Finland the occurrence of F...OH and F...OH...F bonds and the incorporation of (CO32- ions into A and B positions were established.

  4. Study of damage and helium diffusion in fluoro-apatites; Etude de l'endommagement et de la diffusion de l'helium dans des fluoroapatites

    Energy Technology Data Exchange (ETDEWEB)

    Miro, S

    2004-12-15

    This work lies within the scope of the study of the radionuclides containment matrices. The choice of the fluoro-apatites as potential matrices of containment was suggested by the notable properties of these latter (thermal and chemical stability even under radioactive radiation). By irradiations with heavy ions and a helium implantation we simulated the effects related to the alpha radioactivity and to the spontaneous nuclear fission of the radionuclides. Thanks to the study of Durango fluoro-apatite single crystals and fluoro-apatite sintered ceramics, we evidenced that the damage fraction as well as the unit cell deformations increase with the electronic energy loss and with the substitution. These effects are followed at high fluences by a phenomenon of re-crystallization. The study of the helium diffusion points out that the thermal diffusion process improves with the substitution and strongly increases with heavy ions irradiation. (author)

  5. CENOZOIC EXHUMATION OF THE ANTIOQUEÑO PLATEAU, NORTHERN ANDES, COLOMBIA, FROM APATITE LOW-TEMPERATURE THERMOCHRONOLOGY

    Science.gov (United States)

    Restrepo-Moreno, S. A.; Foster, D. A.; O'Sullivan, P. B.; Donelick, R.; Stockli, D. F.

    2009-12-01

    The Antioqueño plateau (AP), in the northernmost Cordillera Central, Colombia, is the most extensive and best preserved relict surface in the Northern Andes. Apatite (U-Th)/He (AHe) and fission track (AFT) results from twenty two samples, collected from paleocrustal depths along two vertical profiles in canyons dissecting the AP, constrain Cenozoic erosional exhumation of this segment of the Andean range. The two profiles exhibit excellent reproducibility of AHe and AFT data. Helium ages increase with elevation from ~22-49 Ma. A marked inflection point in the AHe age-elevation plots at 25 Ma defines the bottom of the post-Oligocene He partial retention zone (PRZ). Virtually invariant ages at ~25 Ma record onset of rapid exhumation in the AP. A more subtle slope change in the PRZ at ~43 Ma is interpreted as a minor exhumation pulse. AFT better defines timing and intensity of Eocene exhumation. AFT ages for both profiles vary from ~30-49 Ma and are consistently older than AHe ages. AFT data display invariant ages (±2σ) between 1500-2400 m elevations while confined track length data exhibit uni-modal distributions with a mean track length of ~14.2 μm. Both facts indicate rapid cooling. This is further supported by virtually concordant AFT and AHe ages for both profiles between 1500 to 2200 m implying that rocks were exhumed from temperatures >120°C to below AHe closure temperature 60°C. Assuming a geothermal gradient of ~25°C/km this corresponds to exhumation rates in the order of 0.5 mm/y, comparable in intensity to the Miocene pulse defined by AHe. Integrated thermal modeling show an episode of rapid cooling at ~43-49 Ma. AFT profiles show an apparent inflection point at ~1400 m, which defines the upper boundary of an apatite partial annealing zone (PAZ) exhumed during the 43-49 Ma cooling event. The position of the PAZ and PRZ relative to the present erosional surface point to average erosion rates of ~0.03 mm/yr, which constitute very low denudation rates

  6. Development of a fission track register dry-method for uranium determination in biological and environmental samples; Desenvolvimento do metodo a seco de registro de tracos de fissao a ser empregado na determinacao de uranio em diversos tipos de amostras biologicas e ambientais

    Energy Technology Data Exchange (ETDEWEB)

    Yamazaki, Ione Makiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil); Geraldo, Luiz Paulo [Universidade Catolica de Santos (UNISANTOS), SP (Brazil). Instituto de Pesquisas Cientificas

    2002-07-01

    In the present work, it was developed a relatively quick and reproducible method for the determination of uranium content, in the ppb level, to be employed in the study of several biological and environmental samples. The technique employed was the fission-track registration in a polycarbonate plastic sheet, commercially known as Makrofol KG (dry-method), together with an automatic discharge chamber system for fission-track counting, using as electrode an aluminized Mylar foil. 5{mu}l droplet of the standard sample solutions, in the form of uranyl nitrate, with U concentrations ranging from 12x10{sup -6} to 50x10{sup -6} g/l, were deposited on Makrofol KG plastic foils, together with 2{mu}l of a 1% cyastat solution (wetting agent), in order to reduce the droplet surface tension. During the deposition, the whole droplet was carefully scattered in such way that large deposit areas, around 7cm{sup 2} were obtained. After evaporation (7 minutes) under a bulb lamp (250 W), the samples were covered by an extremely thin layer (20 {mu}g/cm{sup 2}) of collodion (pyroxylin) in order to fix the dried deposits on the plastic foils. Sets of 12 piled up samples were simultaneously irradiated with neutrons produced by the IPEN IEA-R1 reactor, a 2 MW pool type research reactor. The calibration curve obtained is presented with a discussion of the experimental uncertainties involved. (author)

  7. Fission in a Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Younes, W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-26

    A three-year theory project was undertaken to study the fission process in extreme astrophysical environments, such as the crust of neutron stars. In the first part of the project, the effect of electron screening on the fission process was explored using a microscopic approach. For the first time, these calculations were carried out to the breaking point of the nucleus. In the second part of the project, the population of the fissioning nucleus was calculated within the same microscopic framework. These types of calculations are extremely computer-intensive and have seldom been applied to heavy deformed nuclei, such as fissioning actinides. The results, tools and methodologies produced in this work will be of interest to both the basic-science and nuclear-data communities.

  8. Thermal fission rates with temperature dependent fission barriers

    Science.gov (United States)

    Zhu, Yi; Pei, J. C.

    2016-08-01

    Background: The fission processes of thermal excited nuclei are conventionally studied by statistical models which rely on inputs of phenomenological level densities and potential barriers. Therefore the microscopic descriptions of spontaneous fission and induced fission are very desirable for a unified understanding of various fission processes. Purpose: We propose to study the fission rates, at both low and high temperatures, with microscopically calculated temperature-dependent fission barriers and collective mass parameters. Methods: The fission barriers are calculated by the finite-temperature Skyrme-Hartree-Fock+BCS method. The mass parameters are calculated by the temperature-dependent cranking approximation. The thermal fission rates can be obtained by the imaginary free energy approach at all temperatures, in which fission barriers are naturally temperature dependent. The fission at low temperatures can be described mainly as a barrier-tunneling process. While the fission at high temperatures has to incorporate the reflection above barriers. Results: Our results of spontaneous fission rates reasonably agree with other studies and experiments. The temperature dependencies of fission barrier heights and curvatures have been discussed. The temperature dependent behaviors of mass parameters have also been discussed. The thermal fission rates from low to high temperatures with a smooth connection have been given by different approaches. Conclusions: Since the temperature dependencies of fission barrier heights and curvatures, and the mass parameters can vary rapidly for different nuclei, the microscopic descriptions of thermal fission rates are very valuable. Our studies without free parameters provide a consistent picture to study various fissions such as that in fast-neutron reactors, astrophysical environments, and fusion reactions for superheavy nuclei.

  9. Modernizing the Fission Basis

    Science.gov (United States)

    Tonchev, Anton; Henderson, Roger; Schunck, Nicolas; Sroyer, Mark; Vogt, Ramona

    2016-09-01

    In 1939, Niels Bohr and John Wheeler formulated a theory of neutron-induced nuclear fission based on the hypothesis of the compound nucleus. Their theory, the so-called ``Bohr hypothesis,'' is still at the heart of every theoretical fission model today and states that the decay of a compound nucleus for a given excitation energy, spin, and parity is independent of its formation. We propose the first experiment to validate to 1-2% absolute uncertainties the practical consequences of the Bohr hypothesis during induced nuclear fission. We will compare the fission product yields (FPYs) of the same 240Pu compound nucleus produced via two different reactions (i) n+239Pu and (ii) γ+240 Pu. These high-precision FPYs measurements will be extremely beneficial for our fundamental understanding of the nuclear fission process and nuclear reactions from first principles. This work was performed under the auspices of US DOE by LLNL under Contract DE-AC52-07NA27344. Funding was provided via the LDRD-ERD-069 project.

  10. Fission waves can oscillate

    CERN Document Server

    Osborne, Andrew G

    2016-01-01

    Under the right conditions, self sustaining fission waves can form in fertile nuclear materials. These waves result from the transport and absorption of neutrons and the resulting production of fissile isotopes. When these fission, additional neutrons are produced and the chain reaction propagates until it is poisoned by the buildup of fission products. It is typically assumed that fission waves are soliton-like and self stabilizing. However, we show that in uranium, coupling of the neutron field to the 239U->239Np->239Pu decay chain can lead to a Hopf bifurcation. The fission reaction then ramps up and down, along with the wave velocity. The critical driver for the instability is a delay, caused by the half-life of 239U, between the time evolution of the neutron field and the production of 239Pu. This allows the 239Pu to accumulate and burn out in a self limiting oscillation that is characteristic of a Hopf bifurcation. Time dependent results are obtained using a numerical implementation of a reduced order r...

  11. Determination for β-delayed fission probability of 230Ac

    Institute of Scientific and Technical Information of China (English)

    袁双贵; 杨维凡; 徐岩冰; 肖永厚; 罗亦孝

    2002-01-01

    The 230Ra has been produced via 232Th-2p reaction induced by 60 MeV/u 18O ion irradia-tion of natural thorium. The radium was radiochemically separated from the mixture of thorium andreaction products. Thin Ra sources in which 230Ac was got through 230Ra β- → 230Ac were pre-pared for observing fission fragments from β-delayed fission of 230Ac. The sources were exposedto the mica fission track detectors and measured by the HPGe γ detector. The precursor 230Ac wasidentified by means of observed two fission events as well as γ spectra, and the β-delayed fissionprobability of 230Ac was obtained to be (1.19±0.85) × 10-8.

  12. Fission Product Library and Resource

    Energy Technology Data Exchange (ETDEWEB)

    Burke, J. T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Padgett, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-09-29

    Fission product yields can be extracted from an irradiated sample by performing gamma ray spectroscopy on the whole sample post irradiation. There are several pitfalls to avoid when trying to determine a specific isotope's fission product yield.

  13. RBS and RNRA studies on sorption of europium by apatite

    Energy Technology Data Exchange (ETDEWEB)

    Ohnuki, Toshihiko; Kozai, Naofumi; Isobe, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Murakami, Takashi; Yamamoto, Shunya; Aoki, Yasushi; Naramoto, Hiroshi

    1997-03-01

    The sorption mechanism of europium, alternative of trivalent TRU has been studied based on the depth profiles of elements obtained by Rutherford Backscattering Spectroscopy (RBS) and Resonant Nuclear Reaction Analysis (RNRA). The positive peak for Eu and the negative peak for Ca were observed in the subtracted RBS spectra of the apatites on which Eu was sorbed from that of the fresh apatite. This indicates that Eu was sorbed on apatite, while a fraction of Ca was released from apatite. The peak height for Eu in the RBS spectrum of the apatite obtained at 75degC was higher than that of the apatite at 40degC. The depth profile of hydrogen of the apatite on which Eu was sorbed was similar to that of the fresh apatite. The concentration of Eu in the solution decreased with increasing temperature. On the contrary, the concentration of Ca increased with increasing temperature. Thus, it is concluded that a fraction of Eu is exchanged for Ca in the structure of apatite. (author)

  14. Fission modelling with FIFRELIN

    Energy Technology Data Exchange (ETDEWEB)

    Litaize, Olivier; Serot, Olivier; Berge, Leonie [CEA, DEN, DER, SPRC, Saint Paul Lez Durance (France)

    2015-12-15

    The nuclear fission process gives rise to the formation of fission fragments and emission of particles (n,γ, e{sup -}). The particle emission from fragments can be prompt and delayed. We present here the methods used in the FIFRELIN code, which simulates the prompt component of the de-excitation process. The methods are based on phenomenological models associated with macroscopic and/or microscopic ingredients. Input data can be provided by experiment as well as by theory. The fission fragment de-excitation can be performed within Weisskopf (uncoupled neutron and gamma emission) or a Hauser-Feshbach (coupled neutron/gamma emission) statistical theory. We usually consider five free parameters that cannot be provided by theory or experiments in order to describe the initial distributions required by the code. In a first step this set of parameters is chosen to reproduce a very limited set of target observables. In a second step we can increase the statistics to predict all other fission observables such as prompt neutron, gamma and conversion electron spectra but also their distributions as a function of any kind of parameters such as, for instance, the neutron, gamma and electron number distributions, the average prompt neutron multiplicity as a function of fission fragment mass, charge or kinetic energy, and so on. Several results related to different fissioning systems are presented in this work. The goal in the next decade will be i) to replace some macroscopic ingredients or phenomenological models by microscopic calculations when available and reliable, ii) to be a support for experimentalists in the design of detection systems or in the prediction of necessary beam time or count rates with associated statistics when measuring fragments and emitted particle in coincidence iii) extend the model to be able to run a calculation when no experimental input data are available, iv) account for multiple chance fission and gamma emission before fission, v) account for

  15. Fission modelling with FIFRELIN

    Science.gov (United States)

    Litaize, Olivier; Serot, Olivier; Berge, Léonie

    2015-12-01

    The nuclear fission process gives rise to the formation of fission fragments and emission of particles (n,γ , e-) . The particle emission from fragments can be prompt and delayed. We present here the methods used in the FIFRELIN code, which simulates the prompt component of the de-excitation process. The methods are based on phenomenological models associated with macroscopic and/or microscopic ingredients. Input data can be provided by experiment as well as by theory. The fission fragment de-excitation can be performed within Weisskopf (uncoupled neutron and gamma emission) or a Hauser-Feshbach (coupled neutron/gamma emission) statistical theory. We usually consider five free parameters that cannot be provided by theory or experiments in order to describe the initial distributions required by the code. In a first step this set of parameters is chosen to reproduce a very limited set of target observables. In a second step we can increase the statistics to predict all other fission observables such as prompt neutron, gamma and conversion electron spectra but also their distributions as a function of any kind of parameters such as, for instance, the neutron, gamma and electron number distributions, the average prompt neutron multiplicity as a function of fission fragment mass, charge or kinetic energy, and so on. Several results related to different fissioning systems are presented in this work. The goal in the next decade will be i) to replace some macroscopic ingredients or phenomenological models by microscopic calculations when available and reliable, ii) to be a support for experimentalists in the design of detection systems or in the prediction of necessary beam time or count rates with associated statistics when measuring fragments and emitted particle in coincidence iii) extend the model to be able to run a calculation when no experimental input data are available, iv) account for multiple chance fission and gamma emission before fission, v) account for the

  16. Microscopic modeling of mass and charge distributions in the spontaneous fission of 240Pu

    CERN Document Server

    Sadhukhan, Jhilam; Schunck, Nicolas

    2016-01-01

    In this letter, we outline a methodology to calculate microscopically mass and charge distributions of spontaneous fission yields. We combine the multi-dimensional minimization of collective action for fission with stochastic Langevin dynamics to track the relevant fission paths from the ground-state configuration up to scission. The nuclear potential energy and collective inertia governing the tunneling motion are obtained with nuclear density functional theory in the collective space of shape deformations and pairing. We obtain a quantitative agreement with experimental data and find that both the charge and mass distributions in the spontaneous fission of 240Pu are sensitive both to the dissipation in collective motion and to adiabatic characteristics.

  17. Discoveries of isotopes by fission

    Indian Academy of Sciences (India)

    M Thoennessen

    2015-09-01

    Of the about 3000 isotopes presently known, about 20% have been discovered in fission. The history of fission as it relates to the discovery of isotopes as well as the various reaction mechanisms leading to isotope discoveries involving fission are presented.

  18. Fission dynamics of hot nuclei

    Indian Academy of Sciences (India)

    Santanu Pal; Jhilam Sadhukhan

    2014-04-01

    Experimental evidence accumulated during the last two decades indicates that the fission of excited heavy nuclei involves a dissipative dynamical process. We shall briefly review the relevant dynamical model, namely the Langevin equations for fission. Statistical model predictions using the Kramers’ fission width will also be discussed.

  19. Geochemistry of Apatite from the Apatite-rich Iron Deposits in the Ningwu Region, East Central China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Four types of apatite have been identified in the Ningwu region. The first type of apatite is widely distributed in the middle dark colored zones (i.e. iron ores) of individual deposits. The assemblage includes magnetite, apatite and actinolite (or diopside). The second type occurs within magnetite-apatite veins in the iron ores. The third type is seen in magnetite-apatite veins and (or)nodules in host rocks (i.e. gabbro-diorite porphyry or gabbro-diorite or pyroxene diorite).The fourth type occurs within apatite-pyrite-quartz veins filling fractures in the Xiangshan Group. Rare earth elements (REE) geochemistry of apatite of the four occurrences in porphyry iron deposits is presented. The REE distribution patterns of apatite are generally similar to those of apatites in the Kiruna-type iron ores, nelsonites. They are enriched in light REE, with pronounced negative Eu anomalies. The similarity of REE distribution patterns in apatites from various deposits in different locations in the world indicates a common process of formation for various ore types, e.g.immiscibility. Early magmatic apatites contain 3031.48-12080 ×10-6 REE. Later hydrothermal apatite contains 1958 ×10-6 REE, indicating that the later hydrothermai ore-forming solution contains lower REE. Although gabbro-diorite porphyry and apatite show similar REE patterns, gabbro-diorite porphyries have no europium anomalies or feeble positive or feeble negative europium anomalies,caused both by reduction environment of mantle source region and by fractionation and crystallization (immiscibility) under a high oxygen fugacity condition. Negative Eu anomalies of apatites were formed possibly due to acquisition of Eu2+ by earlier diopsite during ore magma cooling.The apatites in the Aoshan and Taishan iron deposits yield a narrow variation range of 87Sr/86Sr values from 0.7071 to 0.7073, similar to those of the volcanic and subvoicanic rocks, indicating that apatites were formed by liquid immiscibility and

  20. Fission modes of mercury isotopes

    CERN Document Server

    Warda, M; Nazarewicz, W

    2012-01-01

    Recent experiments on beta-delayed fission in the mercury-lead region and the discovery of asymmetric fission in $^{180}$Hg [1] have stimulated renewed interest in the mechanism of fission in heavy nuclei. Here we study fission modes and fusion valleys in $^{180}$Hg and $^{198}$Hg using the self-consistent nuclear density functional theory employing Skyrme and Gogny energy density functionals. We show that the observed transition from asymmetric fission in $^{180}$Hg towards more symmetric distribution of fission fragments in $^{198}$Hg can be explained in terms of competing fission modes of different geometries that are governed by shell effects in pre-scission configurations. The density distributions at scission configurations are studied and related to the experimentally observed mass splits.

  1. Dynamical features of nuclear fission

    Indian Academy of Sciences (India)

    Santanu Pal

    2015-08-01

    It is now established that the transition-state theory of nuclear fission due to Bohr and Wheeler underestimates several observables in heavy-ion-induced fusion–fission reactions. Dissipative dynamical models employing either the Langevin equation or equivalently the Fokker–Planck equation have been developed for fission of heavy nuclei at high excitations (T ∼1 MeV or higher). Here, we first present the physical picture underlying the dissipative fission dynamics. We mainly concentrate upon the Kramers’ prescription for including dissipation in fission dynamics. We discuss, in some detail, the results of a statistical model analysis of the pre-scission neutron multiplicity data from the reactions 19F+194,196,198Pt using Kramers’ fission width. We also discuss the multi-dimensional Langevin equation in the context of kinetic energy and mass distribution of the fission fragments.

  2. Analysis on the Difference between Synthetic Hydroxyapatite and Bone Apatite

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The composition and structure of bone apatite and synthetic hydroxyapatite powder prepared by precipitation method, sol-gel method was studied by FTIR, EMPA, AFM in this paper. The results showed that the composition and phase structure of apatite powder prepared by sol-gel method was most similar with that in the bone. The calcium phosphate ratios of apatite prepared by two kinds of wet precipitation was 1.69, and 1.73 respectively. The calcium phosphate ratio of apatite prepared by sol-gel methnd was 1.66. The apatite powder prepared by sol-gel method was hoped to be more bioactive and biocompatible compared with apatite powder prepared by wet precipitation method. The EMPA results proved that the bone consisted of Ca, P, O, Na, Mg, K, Cl,etc elements. The amount of apatite decreased while amount of collagen increased from the outer layer to inner layer of the bone. AFM results showed that HA particle, with the size about 150-450 nm in length, 100-150 nm in width, 15-40 nm in thickness, grown layer upon layer regularly. The long axis was not always parallel to the collagen fiber. The angle between collagen fiber and apatite lamellar was about 30-45 degree.

  3. IN SITU LEAD STABILIZATION USING NATURAL AND SYNTHETIC APATITE

    Directory of Open Access Journals (Sweden)

    T. Kaluđerović Radoičić

    2008-11-01

    Full Text Available In this work, mineral apatite was investigated for the remediation of lead contamination. Two different apatite minerals were used: synthetic apatite, Ca10(PO46(OH2 (hereafter denoted as HAP and natural apatite from Lisina, near Bosilegrad, Serbia (hereafter denoted as LA. Phosphate ore from Lisina deposit consists of 43.3 % apatite in the form of fluorapatite, Ca10(PO46(F2. Sorption properties of HAP and LA were investigated. The results show that both of these minerals are effective in lead removal from the water solution. Sorption capacity of HAP obtained in this experiment is 0.216 mmol Pb/g HAP, while the value for LA is 0.162 mmol Pb/g LA. Modeling of these systems was conducted using Visual Minteq computer program. The values obtained from the computer simulation were compared to experimental values.

  4. Strongly bound citrate stabilizes the apatite nanocrystals in bone

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Y.-Y.; Rawal, A.; Schmidt-Rohr, K.

    2010-10-12

    Nanocrystals of apatitic calcium phosphate impart the organic-inorganic nanocomposite in bone with favorable mechanical properties. So far, the factors preventing crystal growth beyond the favorable thickness of ca. 3 nm have not been identified. Here we show that the apatite surfaces are studded with strongly bound citrate molecules, whose signals have been identified unambiguously by multinuclear magnetic resonance (NMR) analysis. NMR reveals that bound citrate accounts for 5.5 wt% of the organic matter in bone and covers apatite at a density of about 1 molecule per (2 nm){sup 2}, with its three carboxylate groups at distances of 0.3 to 0.45 nm from the apatite surface. Bound citrate is highly conserved, being found in fish, avian, and mammalian bone, which indicates its critical role in interfering with crystal thickening and stabilizing the apatite nanocrystals in bone

  5. MDD法和裂变径迹法相结合模拟样品的低温热历史——以柴达木盆地北缘赛什腾山中新生代构造演化为例%MODELING THERMAL HISTORY DURING LOW TEMPERATURE BY K-FELDSPAR MDD AND FISSION TRACK:EXAMPLE FROM MESO-CENOZOIC TECTONIC EVOLUTION IN SAISHITENGSHAN IN THE NORTHERN MARGIN OF QAIDAM BASIN

    Institute of Scientific and Technical Information of China (English)

    万景林; 郑德文; 郑文俊; 王伟涛

    2011-01-01

    MDD法和裂变径迹法是2种最常用的低温热年代学方法.通过对它们的测试结果的模拟,揭示出样品经历的热历史,可以有效地延伸这2种方法的研究范围.但是由于模拟的多解性,使得如何制约模拟过程,获得合理的模拟结果显得尤为重要.通过柴达木盆地北缘的模拟过程,展示了模拟中可能存在的问题及提高模拟结果的方法.同时揭示了柴达木盆地北缘中新生代可能存在的3次冷却事件,分别发生在距今约130~150、30~40和5~10Ma.%K-Feldspar MDD( Multiple Diffusion Domain)and fission track are two commonly-used methods in low closure temperature thermal chronometry. By modeling both the feldspar 39Ar/40Ar data and the fission track age and track-length data, the thermal history that sample underwent can be revealed and the effective temperature range of both feldspar 39Ar/40Ar method and fission track method is extended.Because of the multiple resolution of modeling, it is important to restrict the modeling process to gain a reasonable result, though it seems difficult. The possible problem in modeling thermal history is presented in this paper, and the helpful method that can be used to improve the result is illustrated by the sample collected along Saishitengshan in the northern margin of Qaidam Basin. Three rapid cooling events, occurring at 130 ~ 150Ma,30 ~ 40Ma and 5 ~ 10Ma respectively, in northern margin of Qaidam Basin are revealed by feldspar MDD method and fission track method.

  6. Fission yield measurements at IGISOL

    Directory of Open Access Journals (Sweden)

    Lantz M.

    2016-01-01

    Full Text Available The fission product yields are an important characteristic of the fission process. In fundamental physics, knowledge of the yield distributions is needed to better understand the fission process. For nuclear energy applications good knowledge of neutroninduced fission-product yields is important for the safe and efficient operation of nuclear power plants. With the Ion Guide Isotope Separator On-Line (IGISOL technique, products of nuclear reactions are stopped in a buffer gas and then extracted and separated by mass. Thanks to the high resolving power of the JYFLTRAP Penning trap, at University of Jyväskylä, fission products can be isobarically separated, making it possible to measure relative independent fission yields. In some cases it is even possible to resolve isomeric states from the ground state, permitting measurements of isomeric yield ratios. So far the reactions U(p,f and Th(p,f have been studied using the IGISOL-JYFLTRAP facility. Recently, a neutron converter target has been developed utilizing the Be(p,xn reaction. We here present the IGISOL-technique for fission yield measurements and some of the results from the measurements on proton induced fission. We also present the development of the neutron converter target, the characterization of the neutron field and the first tests with neutron-induced fission.

  7. Fission approach to cluster radioactivity

    Indian Academy of Sciences (India)

    D N Poenaru; R A Gherghescu

    2015-09-01

    Fission theory is used to explain decay. Also, the analytical superasymmetric fission (ASAF) model is successfully employed to make a systematic search and to predict, with other models, cluster radioactivity. The macroscopic–microscopic method is illustrated for the superheavy nucleus 286Fl. Then a few results of the theoretical approach of decay (ASAF, UNIV and semFIS models), cluster decay (ASAF and UNIV) and spontaneous fission dynamics are described with Werner–Wheeler and cranking inertia. UNIV denotes universal curve and semFIS the fission-based semiempirical formula.

  8. Hidden systematics of fission channels

    Directory of Open Access Journals (Sweden)

    Schmidt Karl-Heinz

    2013-12-01

    Full Text Available It is a common procedure to describe the fission-fragment mass distributions of fissioning systems in the actinide region by a sum of at least 5 Gaussian curves, one for the symmetric component and a few additional ones, together with their complementary parts, for the asymmetric components. These components have been attributed to the influence of fragment shells, e.g. in the statistical scission-point model of Wilkins, Steinberg and Chasman. They have also been associated with valleys in the potential-energy landscape between the outer saddle and the scission configuration in the multi-channel fission model of Brosa. When the relative yields, the widths and the mean mass-asymmetry values of these components are fitted to experimental data, the mass distributions can be very well reproduced. Moreover, these fission channels are characterised by specific values of charge polarisation, total kinetic energy and prompt-neutron yields. The present contribution investigates the systematic variation of the characteristic fission-channel properties as a function of the composition and the excitation energy of the fissioning system. The mean position of the asymmetric fission channels in the heavy fragment is almost constant in atomic number. The deformation of the nascent fragments at scission, which is the main source of excitation energy of the separated fission fragments ending up in prompt-neutron emission, is found to be a unique function of Z for the light and the heavy fragment of the asymmetric fission channels. A variation of the initial excitation energy of the fissioning system above the fission saddle is only seen in the neutron yield of the heavy fragment. The charge polarisation in the two most important asymmetric fission channels is found to be constant and to appreciably exceed the macroscopic value. The variation of the relative yields and of the positions of the fission channels as a function of the composition and excitation energy

  9. A precursor of β-delayed fission:230Ac

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The 230Ra has been produced via multinucleon transfer and dissipativefragmentation of heavy target in the 60 MeV/u 18O ion reaction with natural thorium.The radium was radiochemically separated from irradiated thorium targets. 230Acwas obtained by 230Ra β-→ 230Ac. Thin Ra sources were prepared for observing fissionfragments from β-delayed fission of 230Ac. The sources were exposed to the micafission track detectors and measured by a HPGe γ detector. The two fission eventswere obtained and could been assigned to theβ-delayed fission of 230Ac. The β-delayedfission probability of 230Ac was determined to be (1.19+0.85) × 10-8.

  10. Measurement of Fission Product Yields from Fast-Neutron Fission

    Science.gov (United States)

    Arnold, C. W.; Bond, E. M.; Bredeweg, T. A.; Fowler, M. M.; Moody, W. A.; Rusev, G.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Henderson, R.; Kenneally, J.; Macri, R.; McNabb, D.; Ryan, C.; Sheets, S.; Stoyer, M. A.; Tonchev, A. P.; Bhatia, C.; Bhike, M.; Fallin, B.; Gooden, M. E.; Howell, C. R.; Kelley, J. H.; Tornow, W.

    2014-09-01

    One of the aims of the Stockpile Stewardship Program is a reduction of the uncertainties on fission data used for analyzing nuclear test data [1,2]. Fission products such as 147Nd are convenient for determining fission yields because of their relatively high yield per fission (about 2%) and long half-life (10.98 days). A scientific program for measuring fission product yields from 235U,238U and 239Pu targets as a function of bombarding neutron energy (0.1 to 15 MeV) is currently underway using monoenergetic neutron beams produced at the 10 MV Tandem Accelerator at TUNL. Dual-fission chambers are used to determine the rate of fission in targets during activation. Activated targets are counted in highly shielded HPGe detectors over a period of several weeks to identify decaying fission products. To date, data have been collected at neutron bombarding energies 4.6, 9.0, 14.5 and 14.8 MeV. Experimental methods and data reduction techniques are discussed, and some preliminary results are presented.

  11. The SPIDER fission fragment spectrometer for fission product yield measurements

    Energy Technology Data Exchange (ETDEWEB)

    Meierbachtol, K.; Tovesson, F. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Shields, D. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Colorado School of Mines, Golden, CO 80401 (United States); Arnold, C. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Blakeley, R. [University of New Mexico, Albuquerque, NM 87131 (United States); Bredeweg, T.; Devlin, M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hecht, A.A.; Heffern, L.E. [University of New Mexico, Albuquerque, NM 87131 (United States); Jorgenson, J.; Laptev, A. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Mader, D. [University of New Mexico, Albuquerque, NM 87131 (United States); O' Donnell, J.M.; Sierk, A.; White, M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2015-07-11

    The SPectrometer for Ion DEtermination in fission Research (SPIDER) has been developed for measuring mass yield distributions of fission products from spontaneous and neutron-induced fission. The 2E–2v method of measuring the kinetic energy (E) and velocity (v) of both outgoing fission products has been utilized, with the goal of measuring the mass of the fission products with an average resolution of 1 atomic mass unit (amu). The SPIDER instrument, consisting of detector components for time-of-flight, trajectory, and energy measurements, has been assembled and tested using {sup 229}Th and {sup 252}Cf radioactive decay sources. For commissioning, the fully assembled system measured fission products from spontaneous fission of {sup 252}Cf. Individual measurement resolutions were met for time-of-flight (250 ps FWHM), spacial resolution (2 mm FHWM), and energy (92 keV FWHM for 8.376 MeV). Mass yield results measured from {sup 252}Cf spontaneous fission products are reported from an E–v measurement.

  12. Energy from nuclear fission(*

    Directory of Open Access Journals (Sweden)

    Ripani M.

    2015-01-01

    Full Text Available The main features of nuclear fission as physical phenomenon will be revisited, emphasizing its peculiarities with respect to other nuclear reactions. Some basic concepts underlying the operation of nuclear reactors and the main types of reactors will be illustrated, including fast reactors, showing the most important differences among them. The nuclear cycle and radioactive-nuclear-waste production will be also discussed, along with the perspectives offered by next generation nuclear assemblies being proposed. The current situation of nuclear power in the world, its role in reducing carbon emission and the available resources will be briefly illustrated.

  13. Acid Vapor Weathering of Apatite and Implications for Mars

    Science.gov (United States)

    Hausrath, E. M.; Golden, D. C.; Morris, R. V.; Ming, D. W.

    2008-03-01

    Acid vapor experiments containing apatite, olivine, glass, and a mixture of these phases suggest that secondary phosphates brushite, strengite and others may have formed. Similar reactions may have formed similar minerals in Paso Robles.

  14. Development of Tributyl Phosphate Apatite for Uranium Removal

    Energy Technology Data Exchange (ETDEWEB)

    Kim, HyunJu; Kang, Jaehyuk; Kim, Jungjin; Uma, Wooyong [POSTECH, Daejeon (Korea, Republic of)

    2015-05-15

    The FTIR results showed that main peaks were shown at 3570 cm-1 in all materials. The band around at 3570 cm-1 indicates the stretching hydroxyl group from HA. Phosphate functional group was observed around at 1040 cm-1. The C-H containing functional group (3000-2950 cm-1) was found only in the TBP-apatite prepared at pH=10 condition. Uranium removal was evaluated under different reaction times, initial U concentrations, and background solution using synthesized HA and TBP-apatite. As NaHCO{sub 3} concentration increased, U removal decreased. In the same condition, TBP-apatite showed better U removal than HA, which indicates TBP-apatite can be used as U removal sorbent.

  15. Membrane biology: fission behind BARs.

    Science.gov (United States)

    Haucke, Volker

    2012-06-05

    Membrane bending is accomplished in part by amphipathic helix insertion into the bilayer and the assembly of BAR domain scaffolds preparing the membrane for fission. Two recent studies highlight the roles of amphipathic helices and BAR scaffolds in membrane fission and establish the structural basis of membrane bending by the N-BAR protein endophilin.

  16. Observations on the Apparent Solubility of Carbonate-Apatites.

    Science.gov (United States)

    Shellis; Lee; Wilson

    1999-10-15

    Previousreports indicating that the apparent solubilities of carbonate-apatites are low appear to conflict with findings that carbonate incorporation into the apatite structure tends to reduce stability. Carbonate-apatites were prepared by a precipitation method and by hydrolysis of monetite and brushite. Apparent solubility profiles were determined by measuring dissolution after exposure for 24 h to acetate buffers with known saturations with respect to hydroxyapatite. All preparations showed a range of apparent solubilities, in agreement with previous work. Precipitated samples had higher apparent solubilities than samples prepared by hydrolysis and this was correlated with differences in crystallinity. Further experiments showed that pyrophosphate ion reduced the apparent solubility, but it was concluded that pyrophosphate occurring naturally in synthetic apatites would be insufficient to cause low apparent solubilities. Microscopical observations showed that precipitated carbonate-apatites were composed of small crystals of uniform size, whereas carbonate-apatites prepared by hydrolysis consisted of both small crystals and very large crystals. The low apparent solubilities observed in the latter preparations are attributed to the large crystals. The surface phenomena possibly involved in apparent solubility behavior are discussed. Copyright 1999 Academic Press.

  17. The role of brushite and octacalcium phosphate in apatite formation.

    Science.gov (United States)

    Johnsson, M S; Nancollas, G H

    1992-01-01

    Studies of apatite mineral formation are complicated by the possibility of forming several calcium phosphate phases. The least soluble, hydroxyapatite (HAP), is preferentially formed under neutral or basic conditions. In more acidic solutions phases such as dicalcium phosphate dihydrate (Brushite, DCPD) and octacalcium phosphate (OCP) are often found. Even under ideal HAP precipitation conditions the precipitates are generally nonstoichiometric, suggesting the formation of calcium-deficient apatites. Both DCPD and OCP have been implicated as possible precursors to the formation of apatite. This may occur by the initial precipitation of DCPD and/or OCP followed by transformation to a more apatitic phase. Although DCPD and OCP are often detected during in vitro crystallization, in vivo studies of bone formation rarely show the presence of these acidic calcium phosphate phases. In the latter case the situation is more complicated, since a large number of ions and molecules are present that can be incorporated into the crystal lattice or adsorbed at the crystallite surfaces. In biological apatite, DCPD and OCP are usually detected only during pathological calcification where the pH is often relatively low. In normal in vivo calcifications these phases have not been found, suggesting the involvement of other precursors or the formation of an initial amorphous calcium phosphate phase (ACP) followed by transformation to apatite.

  18. Insight into Biological Apatite: Physiochemical Properties and Preparation Approaches

    Directory of Open Access Journals (Sweden)

    Quan Liu

    2013-01-01

    Full Text Available Biological apatite is an inorganic calcium phosphate salt in apatite form and nano size with a biological derivation. It is also the main inorganic component of biological hard tissues such as bones and teeth of vertebrates. Consequently, biological apatite has a wide application in dentistry and orthopedics by using as dental fillers and bone substitutes for bone reconstruction and regeneration. Given this, it is of great significance to obtain a comprehensive understanding of its physiochemical and biological properties. However, upon the previous studies, inconsistent and inadequate data of such basic properties as the morphology, crystal size, chemical compositions, and solubility of biological apatite were reported. This may be ascribed to the differences in the source of raw materials that biological apatite are made from, as well as the effect of the preparation approaches. Hence, this paper is to provide some insights rather than a thorough review of the physiochemical properties as well as the advantages and drawbacks of various preparation methods of biological apatite.

  19. 东昆仑东段哈拉郭勒-哈图一带中生代的岩石隆升剥露--锆石和磷灰石裂变径迹年代学证据%Uplift and Exhumation during Mesozoic in Halaguole-Hatu Area, East Segment of Eastern Kunlun Mountains: Evidence from Zircon and Apatite Fission-Track Ages

    Institute of Scientific and Technical Information of China (English)

    王国灿; 向树元; John I. Garver; Robert P. Wintsch; Mary Roden-Tice

    2003-01-01

    根据对东昆仑地区东段哈拉郭勒-哈图一带不同高度基岩的系列锆石裂变径迹年龄分析,结合磷灰石裂变径迹年龄分析和中酸性侵入岩角闪石压力计分析揭示了东昆仑东段中生代的岩石隆升剥露冷却历史.巴隆哈图一带中酸性侵入岩角闪石压力计分析结果反映晚海西-印支期以来的总体剥露幅度约8~9 km,早二叠世至晚三叠世初剥蚀作用极为缓慢,大约为20~40 m/Ma.不同高程样品的锆石裂变径迹年龄分析结果揭示了东昆仑地区东段在中晚侏罗世处于缓慢的岩石隆升剥露阶段,其中中侏罗世相对较快,抬升速率77~88 m/Ma,晚侏罗世相对较慢,抬升速率小于37 m/Ma,且呈减慢趋势,这种减慢趋势反映了早中侏罗世之交强构造抬升期后的逐渐衰退.锆石裂变径迹-磷灰石裂变径迹年龄分析结果反映了中侏罗世以来的剥蚀速率一般不超过55 m/Ma,岩石的剥蚀速率与岩石的抬升速率基本为同一量级,中侏罗世-白垩纪剥蚀作用与岩石抬升作用基本处于平衡状态.

  20. 西藏冈底斯地块尼木地区新第三纪构造热史的磷灰石裂变径迹约束%Apatite Fission Track Evidences for Neogene Tectono-Thermal History in Nimu Area, Southern Gangdese Terrane, Tibet Plateau

    Institute of Scientific and Technical Information of China (English)

    袁万明; 董金泉; 保增宽; 朱炳玉

    2008-01-01

    文章报道冈底斯地块尼木地区磷灰石裂变径迹研究新成果.获得的5个磷灰石裂变径迹年龄为(6.8±0.6)~(9.7±1.2) Ma,均属同一组年龄;径迹长度为(12.9±1.7)~(14.2±2.3) μm,具单峰分布.这与近期9~5 Ma挤压事件并导致藏北盆地快速沉积作用相一致.样品模拟揭示有3阶段地质热历史:从大于12 Ma到8 Ma,温度120~110 ℃,属于稳定阶段;8~4 Ma,约从110 ℃到15 ℃地表温度,是快速冷却阶段;4~0 Ma,处于地表演化阶段.受喜马拉雅碰撞作用的影响,第2阶段使本区急剧隆升剥露,形成现今的山貌特征.在8~4 Ma期间,平均隆升速率为1.41 mm/a,累计隆升量达5 940 m.

  1. MULTIKINETIC MODELLING FOR TIME-TEMPERATURE HISTORY BASED ON APATITE FISSION TRACK DATA%基于磷灰石裂变径迹分析数据的时间-温度历史的多元动力学模拟

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    磷灰石裂变径迹与结晶C轴平行的、与抛光面相交的裂变径迹蚀刻象的最大直径Dpar可以较好地反映磷灰石颗粒的裂变径迹的退火行为.按照Dpar的不同,将同一样品各个磷灰石颗粒的径迹分成几个具有不同动力学性质的成分,然后对这些成分多元动力学成分模拟,使原先"单一”的磷灰石时钟体系变成由若干个独立的热时钟构成的体系,这些独立的热时钟分别记录了样品通过不同温度段的历史,由它们综合而成的历史就更为全面、可靠.本文最后介绍了来自4个盆地的样品的模拟结果.

  2. A NEW APPROACH TO DETERMINE THE EXHUMATION HISTORY OF THE SEDIMENT PROVENANCE∶DETRITAL ZIRCON AND APATITE FISSION-TRACK THERMOCHRONOLOGY%沉积物源区剥露历史分析的一种新途径——碎屑锆石和磷灰石裂变径迹热年代学

    Institute of Scientific and Technical Information of China (English)

    王国灿

    2002-01-01

    介绍了碎屑颗粒锆石和磷灰石裂变径迹年龄法的基本原理、应用前提及方法学.碎屑锆石和磷灰石裂变径迹颗粒年龄法的核心是通过逐一测定计算单颗粒裂变径迹年龄,然后将获得的一批单颗粒年龄进行高斯拟合或二项式拟合,获取其最佳的颗粒年龄分布,从而反演样品的不同源区的热历史.碎屑锆石和磷灰石因其在风化剥蚀搬运过程中具有较高的化学和物理稳定性而成为目前进行颗粒裂变径迹年龄分析中最常用的矿物类型,特别是碎屑锆石的裂变径迹密度大,单颗粒的裂变径迹具有可定年的统计意义,从而成为颗粒裂变径迹测年方法的首选矿物.

  3. The application of the apatite fission track dating to the geothermal history in the northern piedmont zone of the Turpan depression, Xinjiang%吐鲁番坳陷北部山前带地质热历史--磷灰石裂变径迹法研究实例

    Institute of Scientific and Technical Information of China (English)

    金玮; 柳益群; 王成善

    2004-01-01

    笔者应用磷灰石裂变径迹法对吐鲁番坳陷北部山前带的地质热历史进行了综合研究.重点对恰1井、照2井、大步1井的裂变径迹测试结果进行研究,得出北部山前带总体上磷灰石裂变径迹表观年龄随温度增高而逐渐减小,北部山前带的地温梯度古高今低和东高西低的认识.研究结果表明,三叠纪、侏罗纪的烃源岩在侏罗纪开始成熟,两套烃源岩均在侏罗纪末期达生烃高峰,从而得出北部山前带可成为油气勘探可选区的结论.

  4. Thermal History of the Tiereketi Batholith in Altay Mountains, Northern Xinjiang:Evidence from Apatite Fission Track Analysis%新疆阿尔泰铁热克提岩体热历史的磷灰石裂变径迹法研究

    Institute of Scientific and Technical Information of China (English)

    袁万明; 董金泉; 汤云晖; 保增宽

    2004-01-01

    通过对新疆阿尔泰铁热克提岩体4个磷灰石裂变径迹样品分析研究表明,具有3个阶段的热演化模式:①大约 120 Ma之前,温度为105~130 ℃或90~120 ℃,属于较高温稳定期;②60~120 Ma,温度为90~120 ℃或20~65 ℃,系快速冷却与隆升期;③60 Ma以来为20~65 ℃或12~18 ℃,属低温稳定期.第2阶段(60~90 Ma期间),冷却速率为2.5~3.23 ℃/Ma,相当于抬升速率为83.3~107.7 m/Ma.60~120 Ma的快速隆升作用以及80.4~91.9 Ma的裂变径迹年龄,证实燕山晚期发生过新的陆内挤压造山活动.

  5. Fission modes in charged-particle induced fission

    Energy Technology Data Exchange (ETDEWEB)

    Matthies, A.; Kotte, R.; Seidel, W.; Stary, F.; Wohlfarth, D. (Zentralinstitut fuer Kernforschung, Rossendorf bei Dresden (German Democratic Republic))

    1990-12-01

    The population of the three fission modes predicted by Brosa's multi-channel fission model for the uranium region was studied in different fissioning systems. They were produced bombarding {sup 232}Th and {sup 238}U targets by light charged particles with energies slightly above the Coulomb barrier. Though the maximum excitation energy of the compound nucleus amounted to about 22 MeV, the influences of various spherical and deformed nuclear shells on the mass and total kinetic energy distributions of fission fragments are still pronounced. The larger variances of the total kinetic energy distributions compared to those of thermal neutron induced fission were explained by temperature dependent fluctuations of the amount and velocity of alteration of the scission point elongation of the fissioning system. From the ratio of these variances the portion of the potential energy dissipated among intrinsic degrees of freedom before scission was deduced for the different fission channels. It was found that the excitation remaining after pre-scission neutron emission is mainly transferred into intrinsic heat and less into pre-scission kinetic energy. (orig.).

  6. Immobilization of fission products in phosphate ceramic waste forms

    Energy Technology Data Exchange (ETDEWEB)

    Singh, D.; Wagh, A. [Argonne National Lab., IL (United States)

    1997-10-01

    Chemically bonded phosphate ceramics (CBPCs) have several advantages that make them ideal candidates for containing radioactive and hazardous wastes. In general, phosphates have high solid-solution capacities for incorporating radionuclides, as evidenced by several phosphates (e.g., monazites and apatites) that are natural analogs of radioactive and rare-earth elements. The phosphates have high radiation stability, are refractory, and will not degrade in the presence of internal heating by fission products. Dense and hard CBPCs can be fabricated inexpensively and at low temperature by acid-base reactions between an inorganic oxide/hydroxide powder and either phosphoric acid or an acid-phosphate solution. The resulting phosphates are extremely insoluble in aqueous media and have excellent long-term durability. CBPCs offer the dual stabilization mechanisms of chemical fixation and physical encapsulation, resulting in superior waste forms. The goal of this task is develop and demonstrate the feasibility of CBPCs for S/S of wastes containing fission products. The focus of this work is to develop a low-temperature CBPC immobilization system for eluted {sup 99}Tc wastes from sorption processes.

  7. Fission Fragment Angular Distributions measured with a Time Projection Chamber

    Energy Technology Data Exchange (ETDEWEB)

    Kleinrath, Verena [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-04-28

    The subject is presented in a series of slides with the following organization: Introduction (What is anisotropy? Relevance (Theory and ratio cross section), Previous measurements); Experiment (Particle tracking in the fissionTPC, Neutron time of flight, Data analysis & uncertainty calculation, Preliminary result for 235U); and Future Work (Refine 235U result, Process 239Pu data).

  8. Apatite trace element and halogen compositions as petrogenetic-metallogenic indicators: Examples from four granite plutons in the Sanjiang region, SW China

    Science.gov (United States)

    Pan, Li-Chuan; Hu, Rui-Zhong; Wang, Xin-Song; Bi, Xian-Wu; Zhu, Jing-Jing; Li, Chusi

    2016-06-01

    The abundances of trace elements including Sr, Ga and rare earth elements (REE) and halogens in apatite crystals from four intermediate-felsic plutons in the Zhongdian terrane in the Sanjiang region have been determined using electron microprobe and laser ablation inductively coupled plasma mass spectrometry to evaluate the potential of apatite as a petrogenic-metallogenic indicator. The selected plutons include one that is not mineralized (the Triassic Xiuwacu pluton, or the TXWC pluton), one that hosts a porphyry-type Cu deposit (the Pulang pluton, or the PL pluton), one that hosts a porphyry-type Mo deposit (the Tongchanggou pluton, or the TCG pluton), and one that hosts a vein-type Mo deposit (the Cretaceous Xiuwacu pluton, or the CXWC pluton). Except for the CXWC pluton, the other three plutons have adakite-like trace element signatures in whole rocks. The results from this study show that REE, Sr and halogens in apatite can be used to track magma compositions, oxidation states and crystallization history. Apatite crystals from the adakite-like plutons are characterized by much higher Sr/Y and δEu than the non-adakite-type pluton. This means that apatite, which is not susceptible to alteration, is a useful tool for identifying the adakite-like plutons that no longer preserve the initial Sr/Y ratios in whole rocks due to weathering and hydrothermal alteration. Based on apatite Ga contents and δEu values, it is inferred that the parental magmas for the two adakite-like plutons containing porphyry-type Cu and Mo mineralization are more oxidized than that for the non-adakite-type pluton containing vein-type Mo mineralization. Apatite crystals from the vein-type Mo deposit have much lower Cl/F ratios than those from the porphyry-type Cu and Mo deposits. Apatite crystals from the adakite-like pluton without Cu or Mo mineralization is characterized by much lower Cl/F ratios than those from the adakite-like plutons that host the porphyry-type Cu and Mo deposits. The

  9. Apatite at Olympic Dam, South Australia: A petrogenetic tool

    Science.gov (United States)

    Krneta, Sasha; Ciobanu, Cristiana L.; Cook, Nigel J.; Ehrig, Kathy; Kontonikas-Charos, Alkis

    2016-10-01

    The > 10,000 million tonne Olympic Dam Cu-Au-U-Ag deposit, (eastern Gawler Craton, South Australia) is one of the largest orebodies in the World. The deposit is hosted within the Olympic Dam Breccia Complex, placed at the centre of, and resulting from multiple brecciation and Fe-metasomatism of the Roxby Downs Granite (RDG). The latter is part of a larger batholith emplaced at ~ 1.6 Ga. Apatite petrography and chemistry were studied in non-mineralised RDG and coeval granitoids and dolerites, as well as in mineralised RDG from deep (> 2 km) and distal (2.7 km to NE) locations. In both latter cases, although the mineralisation corresponds to the same, early chalcopyrite-pyrite-magnetite ± hematite stage identified in the outer and deeper zones of the deposit itself, the character of granite alteration differs: sericite-chlorite alteration with all feldspar replaced in the deep location; and red-stained K-feldspar on top of prevailing albitization in the distal location. Close-to end-member fluorapatite is a key accessory mineral in all igneous rocks and a common product of early hydrothermal alteration within mineralised granite. Variations in habit, morphology and textures correlate with chemical trends expressed as evolving Cl/F ratios, and concentrations of REE + Y (hereafter REY), Sr, Mn, S, Si and Na. Magmatic apatite is unzoned in the dolerite but features core to REY-enriched rim zonation in the granitoids. Increases in Cl- and Sr-contents correlate with rock basicity. Calculation of Cl in the vapour phase relative to melt at the apatite saturation temperature for zoned apatite in the RDG shows higher values for grains with inclusion-rich cores associated with mafic enclaves, concordant with assimilation of exotic material during magma crystallisation. Hydrothermal alteration of magmatic apatite is most varied in the dolerite where interaction with fluids is expressed as subtle changes in Cl- versus F- and REY-enrichment, and most importantly, S-enrichment in

  10. The spectroscopy of fission fragments

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, W.R. [Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL (United Kingdom); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)

    1998-12-31

    High-resolution measurements on {gamma} rays from fission fragments have provided a rich source of information, unobtainable at the moment in any other way, on the spectroscopy of neutron-rich nuclei. In recent years important data have been obtained on the yrast- and near yrast-structure of neutron-rich fission fragments. We discuss the scope of measurements which can be made on prompt gamma rays from secondary fission fragments, the techniques used in the experiments and some results recently obtained. (author) 24 refs., 8 figs., 1 tab.

  11. Intrinsic energy partition in fission

    Directory of Open Access Journals (Sweden)

    Mirea M.

    2013-03-01

    Full Text Available The intrinsic energy partition between two complementary fission fragments is investigated microscopically. The intrinsic excitation energy of fission fragments is dynamically evaluated in terms of the time-dependent pairing equations. These equations are corroborated with two conditions. One of them fixes the number of particles and the other separates the pairing active spaces associated to the two fragments in the vicinity of the scission configuration. The excitation energy in a wide distribution of fission fragments is calculated for the 234U parent nucleus.

  12. UV photofunctionalization promotes nano-biomimetic apatite deposition on titanium

    Directory of Open Access Journals (Sweden)

    Saita M

    2016-01-01

    Full Text Available Makiko Saita,1 Takayuki Ikeda,1,2 Masahiro Yamada,1,3 Katsuhiko Kimoto,4 Masaichi Chang-Il Lee,5 Takahiro Ogawa1 1Division of Advanced Prosthodontics, Weintraub Center for Reconstructive Biotechnology, UCLA School of Dentistry, Los Angeles, CA, USA; 2Department of Complete Denture Prosthodontics, Nihon University School of Dentistry, Yokosuka, Japan; 3Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan; 4Department of Prosthodontics and Oral Rehabilitation, 5Yokosuka-Shonan Disaster Health Emergency Research Center and ESR Laboratories, Kanagawa Dental University Graduate School of Dentistry, Yokosuka, Japan Background: Although biomimetic apatite coating is a promising way to provide titanium with osteoconductivity, the efficiency and quality of deposition is often poor. Most titanium implants have microscale surface morphology, and an addition of nanoscale features while preserving the micromorphology may provide further biological benefit. Here, we examined the effect of ultraviolet (UV light treatment of titanium, or photofunctionalization, on the efficacy of biomimetic apatite deposition on titanium and its biological capability.Methods and results: Micro-roughed titanium disks were prepared by acid-etching with sulfuric acid. Micro-roughened disks with or without photofunctionalization (20-minute exposure to UV light were immersed in simulated body fluid (SBF for 1 or 5 days. Photofunctionalized titanium disks were superhydrophilic and did not form surface air bubbles when immersed in SBF, whereas non-photofunctionalized disks were hydrophobic and largely covered with air bubbles during immersion. An apatite-related signal was observed by X-ray diffraction on photofunctionalized titanium after 1 day of SBF immersion, which was equivalent to the one observed after 5 days of immersion of control titanium. Scanning electron microscopy revealed nodular apatite deposition

  13. Study on apatite compounds; Apataitokei kagobutsu ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-11-28

    To clarify the material properties of apatite compounds, the synthesis method, and the evaluation of physical properties of material and elementary technology were investigated. For the study on synthesis and crystal growth, a method of precipitating calcium phosphate on the surface of metal was investigated by means of relatively mild electrolytic method using liquid phase system. A new molding method of Ca defective apatite was established. Composite similar to vital bone was prepared by means of a new low-temperature sintering. For the study on chemical properties, from the model experiments, it was found that the self-organizing phenomenon, which is observed in the composite of apatite and collagen, happened between the organic single molecular film and crystal of apatite. For the study on evaluation of physical properties and elementary technology, the surface and interface of ceramics such as apatite were investigated by means of spectroscopy, the electronic state was analyzed by the quantum chemical calculation, and the crystalline structure was analyzed using X-ray equipment. 270 refs., 102 figs., 10 tabs.

  14. Interaction between a bisphosphonate, tiludronate, and biomimetic nanocrystalline apatites.

    Science.gov (United States)

    Pascaud, Patricia; Gras, Pierre; Coppel, Yannick; Rey, Christian; Sarda, Stéphanie

    2013-02-19

    Bisphosphonates (BPs) are well established as successful antiresorptive agents for the prevention and treatment of bone diseases such as osteoporosis and Paget's disease. The aim of this work was to clarify the reaction mechanisms between a BP molecule, tiludronate, and the nanocrystalline apatite surface. The adsorption of tiludronate on well-characterized synthetic biomimetic nanocrystalline apatites with homogeneous but different compositions and surface characteristics was investigated to determine the effect of the nanocrystalline apatite substrate on the adsorption behavior. The results show that the adsorption of tiludronate on nanocrystalline biomimetic apatite surfaces varies over a large range. The most immature apatitic samples exhibited the highest affinity and the greatest amount adsorbed at saturation. Maturation of the nanocrystals induces a decrease of these values. The amount of phosphate ion released per adsorbed BP molecule varied, depending on the nanocrystalline substrate considered. The adsorption mechanism, although associated with a release of phosphate ions, cannot be considered as a simple ion exchange process involving one or two phosphate ions on the surface. A two-step process is proposed consisting of a surface binding of BP groups to calcium ions associated with a proton release inducing the protonation of surface orthophosphate ions and their eventual solubilization.

  15. Advanced Space Fission Propulsion Systems

    Science.gov (United States)

    Houts, Michael G.; Borowski, Stanley K.

    2010-01-01

    Fission has been considered for in-space propulsion since the 1940s. Nuclear Thermal Propulsion (NTP) systems underwent extensive development from 1955-1973, completing 20 full power ground tests and achieving specific impulses nearly twice that of the best chemical propulsion systems. Space fission power systems (which may eventually enable Nuclear Electric Propulsion) have been flown in space by both the United States and the Former Soviet Union. Fission is the most developed and understood of the nuclear propulsion options (e.g. fission, fusion, antimatter, etc.), and fission has enjoyed tremendous terrestrial success for nearly 7 decades. Current space nuclear research and technology efforts are focused on devising and developing first generation systems that are safe, reliable and affordable. For propulsion, the focus is on nuclear thermal rockets that build on technologies and systems developed and tested under the Rover/NERVA and related programs from the Apollo era. NTP Affordability is achieved through use of previously developed fuels and materials, modern analytical techniques and test strategies, and development of a small engine for ground and flight technology demonstration. Initial NTP systems will be capable of achieving an Isp of 900 s at a relatively high thrust-to-weight ratio. The development and use of first generation space fission power and propulsion systems will provide new, game changing capabilities for NASA. In addition, development and use of these systems will provide the foundation for developing extremely advanced power and propulsion systems capable of routinely and affordably accessing any point in the solar system. The energy density of fissile fuel (8 x 10(exp 13) Joules/kg) is more than adequate for enabling extensive exploration and utilization of the solar system. For space fission propulsion systems, the key is converting the virtually unlimited energy of fission into thrust at the desired specific impulse and thrust

  16. Fission hindrance and nuclear viscosity

    Indian Academy of Sciences (India)

    Indranil Mazumdar

    2015-08-01

    We discuss the role of nuclear viscosity in hindering the fission of heavy nuclei as observed in the experimental measurements of GDR -ray spectra from the fissioning nuclei. We review a set of experiments carried out and reported by us previously [see Dioszegi et al, Phys. Rev. C 61, 024613 (2000); Shaw et al, Phys. Rev. C 61, 044612 (2000)] and argue that the nuclear viscosity parameter has no apparent dependence on temperature. However, it may depend upon the deformation of the nucleus.

  17. Electrochemical Studies of Paraquat Adsorbed onto Crystalline Apatite

    Directory of Open Access Journals (Sweden)

    Moulay Abderrahim EL MHAMMEDI

    2007-09-01

    Full Text Available The carbon paste electrode (CPE has been used to analyze the electrochemical behavior of paraquat (PQ adsorbed onto synthesized hydroxyapatite phosphocalcique (HAP in K2SO4 (0.1M. The cyclic voltammetry results obtained corrobate with square wave voltammetry. The influence of variables such as the concentration of paraquat adsorbed onto apatite (PQ/HAP, and the potential scan rate was tested.X-ray diffraction analysis (XRD, Fourier transformed infrared spectroscopy (FTIR analysis and inductively coupled plasma-atomic emission spectrometry (ICP, AES were used for characterization of the apatite.

  18. Apatite crystal in hard tissue of conodont fossils

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The present study was aimed at examining the nature of apatite crystal in the tooth apparatus of a conodont fossil using transmission electron microscopy (TEM),scanning electron microscopy (SEM),laser Raman microprobe spectrometry and electron-probe microanalysis (EPMA).The hard tissue of the condont consisted of 2 layers and the organization varied with the size of the crystal.Higher magnification showed that the crystals were observed in the lattice of (100) and the central dark lines were not present.Ca,P,and F were detected in the crystal using EPMA.Our results indicate that the apatite crystal in conodont fossils is not hydroxyapatite but fluorapatite.

  19. Science and technology with nuclear tracks in solids

    CERN Document Server

    Buford-Price, P

    2005-01-01

    Fission track dating has greatly expanded its usefulness to geology over the last 40 years. It is central to thermochronology—the use of shortened fission tracks to decipher the thermal history, movement, and provenance of rocks. When combined with other indicators, such as zircon color and (U–Th)/He, a range of temperatures from C to C can be studied. Combining fission track analysis with cosmogenic nuclide decay rates, one can study landscape development and denudation of passive margins. Technological applications have expanded from biological filters, radon mapping, and dosimetry to the use of ion track microtechnology in microlithography, micromachining by ion track etching, microscopic field emission tips, magnetic nanowires as magnetoresistive sensors, microfluidic devices, physiology of ion channels in single cells, and so on. In nuclear and particle physics, relatively insensitive glass detectors have been almost single-handedly responsible for our knowledge of cluster radioactivity, and plastic ...

  20. Depressing effect of sodium hexametaphosphate on apatite in flotation of rutile

    Institute of Scientific and Technical Information of China (English)

    Hao Ding; Hai Lin; Yanxi Deng

    2007-01-01

    The separation of mtile from apatite by flotation and the mechanism of depressing the apatite of sodium hexametaphosphate were studied. The results showed that rutile and apatite could be separated by using alkyl-imino-bismethylene phosphoric acid and sodium hexametaphosphate as a collector and a regulator, respectively. Sodium hexametaphosphate could selectively dissolve calcium ions on the apatite surface, and make calcium ions break away from lattice binding through combining.

  1. An apatite for progress:inclusions in zircon and titanite constrain petrogenesis and provenance

    OpenAIRE

    Bruand, Emilie; Storey, Craig Darryl; Fowler, Michael

    2016-01-01

    Apatite has recently gained considerable attention as a mineral with many uses within the Earth and planetary sciences. Apatite chemistry has recently given new insight into a wide range of geological processes and tools, for example, magmatism, metasomatism, planetary geochemistry, and geochronology. We expand the utility of apatite here by presenting a novel way to fingerprint magma chemistry and petrogenesis using apatite inclusions within robust titanite and zircon. We present trace eleme...

  2. Diallyl phthalate (DAP) solid state nuclear track detector

    CERN Document Server

    Koguchi, Y; Ashida, T; Tsuruta, T

    2003-01-01

    Diallyl phthalate (DAP) solid state nuclear track detector is suitable for detecting heavy ions such as fission fragments, because it is insensitive to right ions such as alpha particles and protons. Detection efficiency of fission tracks is about 100%, which is unaffected under conditions below 240degC lasting for 1h or below 1 MGy of gamma-ray irradiation. Optimum etching condition for the DAP detector for detection of fission fragments is 2-4 h using 30% KOH aqueous solution at 90degC or 8-15 min using PEW-65 solution at 60degC. DAP detector is useful in detecting induced fission tracks for dating of geology or measuring intense heavy ions induced by ultra laser plasma. The fabrication of copolymers of DAP and CR-39 makes it possible to control the discrimination level for detection threshold of heavy ions. (author)

  3. Assessment of fissionable material behaviour in fission chambers

    Energy Technology Data Exchange (ETDEWEB)

    Cabellos, O., E-mail: oscar.cabellos@upm.e [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, 28006 Madrid (Spain); Department of Nuclear Engineering, Universidad Politecnica de Madrid, 28006 Madrid (Spain); Fernandez, P. [Department of Nuclear Engineering, Universidad Politecnica de Madrid, 28006 Madrid (Spain); Rapisarda, D. [Laboratorio Nacional de Fusion, EURATOM-CIEMAT, 28040 Madrid (Spain); Garcia-Herranz, N. [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, 28006 Madrid (Spain); Department of Nuclear Engineering, Universidad Politecnica de Madrid, 28006 Madrid (Spain)

    2010-06-21

    A comprehensive study is performed in order to assess the pertinence of fission chambers coated with different fissile materials for high neutron flux detection. Three neutron scenarios are proposed to study the fast component of a high neutron flux: (i) high neutron flux with a significant thermal contribution such as BR2, (ii) DEMO magnetic fusion reactor, and (iii) IFMIF high flux test module. In this study, the inventory code ACAB is used to analyze the following questions: (i) impact of different deposits in fission chambers; (ii) effect of the irradiation time/burn-up on the concentration; (iii) impact of activation cross-section uncertainties on the composition of the deposit for all the range of burn-up/irradiation neutron fluences of interest. The complete set of nuclear data (decay, fission yield, activation cross-sections, and uncertainties) provided in the EAF2007 data library are used for this evaluation.

  4. Fission gas in thoria

    Science.gov (United States)

    Kuganathan, Navaratnarajah; Ghosh, Partha S.; Galvin, Conor O. T.; Arya, Ashok K.; Dutta, Bijon K.; Dey, Gautam K.; Grimes, Robin W.

    2017-03-01

    The fission gases Xe and Kr, formed during normal reactor operation, are known to degrade fuel performance, particularly at high burn-up. Using first-principles density functional theory together with a dispersion correction (DFT + D), in ThO2 we calculate the energetics of neutral and charged point defects, the di-vacancy (DV), different neutral tri-vacancies (NTV), the charged tetravacancy (CTV) defect cluster geometries and their interaction with Xe and Kr. The most favourable incorporation point defect site for Xe or Kr in defective ThO2 is the fully charged thorium vacancy. The lowest energy NTV in larger supercells of ThO2 is NTV3, however, a single Xe atom is most stable when accommodated within a NTV1. The di-vacancy (DV) is a significantly less favoured incorporation site than the NTV1 but the CTV offers about the same incorporation energy. Incorporation of a second gas atom in a NTV is a high energy process and more unfavourable than accommodation within an existing Th vacancy. The bi-NTV (BNTV) cluster geometry studied will accommodate one or two gas atoms with low incorporation energies but the addition of a third gas atom incurs a high energy penalty. The tri-NTV cluster (TNTV) forms a larger space which accommodates three gas atoms but again there is a penalty to accommodate a fourth gas atom. By considering the energy to form the defect sites, solution energies were generated showing that in ThO2-x the most favourable solution equilibrium site is the NTV1 while in ThO2 it is the DV.

  5. Nuclear fission and neutron-induced fission cross-sections

    CERN Document Server

    James, G D; Michaudon, A; Michaudon, A; Cierjacks, S W; Chrien, R E

    2013-01-01

    Nuclear Fission and Neutron-Induced Fission Cross-Sections is the first volume in a series on Neutron Physics and Nuclear Data in Science and Technology. This volume serves the purpose of providing a thorough description of the many facets of neutron physics in different fields of nuclear applications. This book also attempts to bridge the communication gap between experts involved in the experimental and theoretical studies of nuclear properties and those involved in the technological applications of nuclear data. This publication will be invaluable to those interested in studying nuclear fis

  6. Dynamics of rotationally fissioned asteroids: Source of observed small asteroid systems

    CERN Document Server

    Jacobson, Seth A

    2014-01-01

    We present a model of near-Earth asteroid (NEA) rotational fission and ensuing dynamics that describes the creation of synchronous binaries and all other observed NEA systems including: doubly synchronous binaries, high- e binaries, ternary systems, and contact binaries. Our model only presupposes the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, "rubble pile" asteroid geophysics, and gravitational interactions. The YORP effect torques a "rubble pile" asteroid until the asteroid reaches its fission spin limit and the components enter orbit about each other (Scheeres, D.J. [2007]. Icarus 189, 370-385). Non-spherical gravitational potentials couple the spin states to the orbit state and chaotically drive the system towards the observed asteroid classes along two evolutionary tracks primarily distinguished by mass ratio. Related to this is a new binary process termed secondary fission - the secondary asteroid of the binary system is rotationally accelerated via gravitational torques until it fissions, thu...

  7. Experimental approach to fission process of actinides

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Hiroshi [Osaka Univ., Toyonaka (Japan). Faculty of Science

    1997-07-01

    From experimental views, it seems likely that the mechanism of nuclear fission process remains unsolved even after the Bohr and Weeler`s study in 1939. Especially, it is marked in respect of mass distribution in unsymmetric nuclear fission. The energy dependency of mass distribution can be explained with an assumption of 2-mode nuclear fission. Further, it was demonstrated that the symmetrical fission components and the unsymmetrical ones have different saddle and fission points. Thus, the presence of the 2-mode fission mechanism was confirmed. Here, transition in the nuclear fission mechanism and its cause were investigated here. As the cause of such transition, plausible four causes; a contribution of multiple-chance fission, disappearance of shell effects, beginning of fission following collective excitation due to GDR and nuclear phase transition were examined in the condition of excitation energy of 14.0 MeV. And it was suggested that the transition in the nuclear fission concerned might be related to phase transition. In addition, the mechanism of nuclear fission at a low energy and multi-mode hypothesis were examined by determination of the energy for thermal neutron fission ({sup 233,235}U and {sup 239}Pu) and spontaneous nuclear fission ({sup 252}Cf). (M.N.)

  8. Lead Speciation and Bioavailability in Apatite-Amended Sediments

    Directory of Open Access Journals (Sweden)

    Kirk G. Scheckel

    2011-01-01

    Full Text Available The in situ sequestration of lead (Pb in sediment with a phosphate amendment was investigated by Pb speciation and bioavailability. Sediment Pb in preamendment samples was identified as galena (PbS with trace amounts of absorbed Pb. Sediment exposed to atmospheric conditions underwent conversion to hydrocerussite and anglesite. Sediments mixed with apatite exhibited limited conversion to pyromorphite, the hypothesized end product. Conversion of PbS to pyromorphite is inhibited under reducing conditions, and pyromorphite formation appears limited to reaction with pore water Pb and PbS oxidation products. Porewater Pb values were decreased by 94% or more when sediment was amended with apatite. The acute toxicity of the sediment Pb was evaluated with Hyalella azteca and bioaccumulation of Pb with Lumbriculus variegatus. The growth of H. azteca may be mildly inhibited in contaminated sediment, with apatite-amended sediments exhibiting on average a higher growth weight by approximately 20%. The bioaccumulation of Pb in L. variegatus tissue decreased with increased phosphate loading in contaminated sediment. The study indicates limited effectiveness of apatite in sequestering Pb if present as PbS under reducing conditions, but sequestration of porewater Pb and stabilization of near-surface sediment may be a feasible and alternative approach to decreasing potential toxicity of Pb.

  9. Biomimetic nanocrystalline apatites: Emerging perspectives in cancer diagnosis and treatment.

    Science.gov (United States)

    Al-Kattan, Ahmed; Girod-Fullana, Sophie; Charvillat, Cédric; Ternet-Fontebasso, Hélène; Dufour, Pascal; Dexpert-Ghys, Jeannette; Santran, Véronique; Bordère, Julie; Pipy, Bernard; Bernad, José; Drouet, Christophe

    2012-02-14

    Nanocrystalline calcium phosphate apatites constitute the mineral part of hard tissues, and the synthesis of biomimetic analogs is now well-mastered at the lab-scale. Recent advances in the fine physico-chemical characterization of these phases enable one to envision original applications in the medical field along with a better understanding of the underlying chemistry and related pharmacological features. In this contribution, we specifically focused on applications of biomimetic apatites in the field of cancer diagnosis or treatment. We first report on the production and first biological evaluations (cytotoxicity, pro-inflammatory potential, internalization by ZR-75-1 breast cancer cells) of individualized luminescent nanoparticles based on Eu-doped apatites, eventually associated with folic acid, for medical imaging purposes. We then detail, in a first approach, the preparation of tridimensional constructs associating nanocrystalline apatite aqueous gels and drug-loaded pectin microspheres. Sustained releases of a fluorescein analog (erythrosin) used as model molecule were obtained over 7 days, in comparison with the ceramic or microsphere reference compounds. Such systems could constitute original bone-filling materials for in situ delivery of anticancer drugs.

  10. Apatite accumulation enhances the mechanical property of anammox granules

    NARCIS (Netherlands)

    Lin, Y. M.; Lotti, T.; Sharma, P. K.; van Loosdrecht, M. C. M.

    2013-01-01

    The strength of granular sludge is essential for the mechanical stability of the granules. Inorganic precipitants form a major factor influencing the strength of the granules. To check the possibility of apatite accumulation in anammox granules, and study its contribution to the mechanical strength

  11. NIFFTE Time Projection Chamber for Fission Cross Section Measurements

    Science.gov (United States)

    Castillo, Ryan; Neutron Induced Fission Fragment Tracking Experiment Collaboration

    2011-10-01

    In order to design safer and more efficient Generation IV nuclear reactors, more accurate knowledge of fission cross sections is needed. The goal of the Time Projection Chamber (TPC) used by the Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration is to measure the cross sections of several fissile materials to within 1% uncertainty. The ability of the TPC to produce 3D ``pictures'' of charged particle trajectories will eliminate unwanted alpha particles in the data. Another important source of error is the normalization of data the U-235 standard. NIFFTE will use the H(n,n)H reaction instead, which is known to better than 0.2%. The run control and monitoring system will eventually allow for nearly complete automation and off-site monitoring of the experiment. This presentation will cover the need for precision measurements and an overview of the experiment. This work was supported by the U.S. Department of Energy Division of Energy Research.

  12. Search for Singlet Fission Chromophores

    Energy Technology Data Exchange (ETDEWEB)

    Havlas, Z.; Akdag, A.; Smith, M. B.; Dron, P.; Johnson, J. C.; Nozik, A. J.; Michl, J.

    2012-01-01

    Singlet fission, in which a singlet excited chromophore shares its energy with a ground-state neighbor and both end up in their triplet states, is of potential interest for solar cells. Only a handful of compounds, mostly alternant hydrocarbons, are known to perform efficiently. In view of the large number of conditions that a successful candidate for a practical cell has to meet, it appears desirable to extend the present list of high performers to additional classes of compounds. We have (i) identified design rules for new singlet fission chromophores and for their coupling to covalent dimers, (ii) synthesized them, and (iii) evaluated their performance as neat solids or covalent dimers.

  13. Spontaneous fission of superheavy nuclei

    Indian Academy of Sciences (India)

    R A Gherghescu; D N Poenaru

    2015-09-01

    The macroscopic–microscopic method is extended to calculate the deformation energy and penetrability for binary nuclear configurations typical for fission processes. The deformed two-centre shell model is used to obtain single-particle energy levels for the transition region of two partially overlapped daughter and emitted fragment nuclei. The macroscopic part is obtained using the Yukawa-plus-exponential potential. The microscopic shell and pairing corrections are obtained using the Strutinsky and BCS approaches and the cranking formulae yield the inertia tensor. Finally, the WKB method is used to calculate penetrabilities and spontaneous fission half-lives. Calculations are performed for the decay of 282,292120 nuclei.

  14. FIssion Product Prompt γ-ray spectrometer: Development of an instrumented gas-filled magnetic spectrometer at the ILL

    Science.gov (United States)

    Blanc, A.; Chebboubi, A.; Faust, H.; Jentschel, M.; Kessedjian, G.; Köster, U.; Materna, T.; Panebianco, S.; Sage, C.; Urban, W.

    2013-12-01

    Accurate thermal neutron-induced fission data are important for applications in reactor physics as well as for fundamental nuclear physics. FIPPS is the new FIssion Product Prompt γ-ray Spectrometer being developed at the Institut Laue Langevin for neutron-induced fission studies. FIPPS is based on the combination of a large Germanium detector array surrounding a fission target, a Time-Of-Flight detector and a Gas-Filled Magnet (GFM) to identify mass, nuclear charge and kinetic energy of one of the fission fragments. The GFM will be instrumented with a Time-Projection Chamber (TPC) for individual 3D tracking of the fragments. A conceptual design study of the new spectrometer is presented.

  15. Development of Biomimetic Needle-like Apatite Nanocrystals by a Simple New Method

    Institute of Scientific and Technical Information of China (English)

    Jie WEI; Yubao LI; Yi ZUO; Xueling PENG; Li ZHANG

    2004-01-01

    A new method of calcium nitrate and sodium phosphate as reactants was employed to prepare biomimetic apatite nanocrystals by a simple heating treatment in water. The structure and properties of the apatite crystals were investigated by TEM, XRD, IR, ICP and TG. It is found that the apatite nanocrystals contain OH-, CO32-, Na+ and HPO~- ions in their crystal structure. The crystal water is removed during heating from 200℃ to 400℃. CO32-and HPO~- are decomposed at 600℃ to 800℃, also there is lattice water lost at this temperature stage. The morphology of the apatite nanocrystals is needle-like with a length less than 80 nm. The size and crystallinity of the apatite nanocrystals increase with water treatment temperature and time. Compared to the apatite crystals sintered at 800℃, water treated apatite nanocrystals are poorly crystallized apatite. The results indicate that the apatite nanocrystals have similarity in composition, structure, morphology and crystallinity to that of bone apatite crystals. It can be used to make apatite crystals/polymer biomimetic bone repair materials or for other biomedical applications.

  16. Fission Track Dating on the Paodaoling Gold Deposit in the Middle-Lower Yangtze River Metallogenic Belt: Its significance to Tectonic Setting%长江中下游成矿带抛刀岭金矿裂变径迹研究及大地构造意义

    Institute of Scientific and Technical Information of China (English)

    田朋飞; 杨晓勇; 袁万明; 刘海涛; 薛斌

    2012-01-01

    抛刀岭金矿位于长江中下游成矿带中的安庆贵池矿集区,是长江中下游多金属成矿带中首次发现的斑岩型独立金矿床.通过磷灰石裂变径迹研究分析区内的构造演化特征,裂变径迹长度处于11.9±1.8μm和13.2±1.6μm之间,表明样品在后期受构造热事件的影响,样品长时间处于退火带温度,长度直方图总体呈现单峰特征,受隆升冷却作用控制明显.通过对同组年龄(x2检验值>5%)和混合年龄(x2检验值<5%)进行分析,所测年龄位于123Ma和19Ma之间,可以将年龄分为5组:123.0Ma,107Ma,86Ma,52Ma,19Ma.裂变径迹热历史可以分为4个时期:缓慢冷却期,从150~90Ma;快速冷却期,从90Ma至65~58Ma;缓慢冷却期,从65~58Ma至18~12Ma;快速降温期,从18~12Ma至今.自中侏罗世以来,江南隆起带受控于太平洋板块构造,太平洋板块在不同时期有着不同的活动,其运移方向和活动强度直接控制着中国东部的构造演化.研究地区所测裂变径迹年龄划分时代与太平洋形成后不同产状洋岛链出现的时代吻合,热历史模拟结果和太平洋板块不同期次活动相关.通过热历史模拟和构造分析,可推测热历史不同阶段的形成是不同时期太平洋板块运动的结果,样品混合年龄亦证明了构造活动的多期次性.可以推断贵池地区自白垩纪以来的构造运动与太平洋构造带活动密切相关,其多期构造演化是对太平洋板块活动的响应.%The Paodaoling gold deposit regarding as an independent prophyry gold deposit is firstly found in Anqing-Guichi ore district within the middle-lower Yangtze River polymetallic metallogenetic belt. One the study of fission tracks, we analyze the characteristics of structural evolution in the Paodaoling gold deposit. Results show that the mean track lengths range between 11. 9±1. 8μm and 13. 2 + 1. 6μm, respectively! Indicating that intrusions are infulenced by tectonic-thermal events

  17. Biomimetic synthesis and biocompatibility evaluation of carbonated apatites template-mediated by heparin

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Yi [Department of Oral and Maxillofacial Surgery, Laboratory of Interdisciplinary Studies, School and Hospital of Stomatology, Peking University, Beijing 100081 (China); Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Sun, Yuhua [Department of Oral and Maxillofacial Surgery, Laboratory of Interdisciplinary Studies, School and Hospital of Stomatology, Peking University, Beijing 100081 (China); Chen, Xiaofang [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Zhu, Peizhi, E-mail: pzzhu@umich.edu [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Wei, Shicheng, E-mail: sc-wei@pku.edu.cn [Department of Oral and Maxillofacial Surgery, Laboratory of Interdisciplinary Studies, School and Hospital of Stomatology, Peking University, Beijing 100081 (China); Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China)

    2013-07-01

    Biomimetic synthesis of carbonated apatites with good biocompatibility is a promising strategy for the broadening application of apatites for bone tissue engineering. Most researchers were interested in collagen or gelatin-based templates for synthesis of apatite minerals. Inspired by recent findings about the important role of polysaccharides in bone biomineralization, here we reported that heparin, a mucopolysaccharide, was used to synthesize carbonated apatites in vitro. The results indicated that the Ca/P ratio, carbon content, crystallinity and morphology of the apatites varied depending on the heparin concentration and the initial pH value. The morphology of apatite changed from flake-shaped to needle-shaped, and the degree of crystallinity decreased with the increasing of heparin concentration. Biocompatibility of the apatites was tested by proliferation and alkaline phosphatase activity of MC3T3-E1 cells. The results suggested that carbonated apatites synthesized in the presence of heparin were more favorable to the proliferation and differentiation of MC3T3-E1 cells compared with traditional method. In summary, the heparin concentration and the initial pH value play a key role in the chemical constitution and morphology, as well as biological properties of apatites. These biocompatible nano-apatite crystals hold great potential to be applied as bioactive materials for bone tissue engineering. - Highlights: • Heparin was used as a template to synthesize needle-shaped nano-apatite. • Changing the pH value and concentration led to different properties of apatite. • Apatite prepared by heparin was more favorable to the osteogenic differentiation. • Possible synthesis mechanism of apatite templated by heparin was described.

  18. Radiochemistry and the Study of Fission

    Energy Technology Data Exchange (ETDEWEB)

    Rundberg, Robert S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-11-14

    These are slides from a lecture given at UC Berkeley. Radiochemistry has been used to study fission since it’ discovery. Radiochemical methods are used to determine cumulative mass yields. These measurements have led to the two-mode fission hypothesis to model the neutron energy dependence of fission product yields. Fission product yields can be used for the nuclear forensics of nuclear explosions. The mass yield curve depends on both the fuel and the neutron spectrum of a device. Recent studies have shown that the nuclear structure of the compound nucleus can affect the mass yield distribution. The following topics are covered: In the beginning: the discovery of fission; forensics using fission products: what can be learned from fission products, definitions of R-values and Q-values, fission bases, K-factors and fission chambers, limitations; the neutron energy dependence of the mass yield distribution (the two mode fission hypothesis); the influence of nuclear structure on the mass yield distribution. In summary: Radiochemistry has been used to study fission since it’s discovery. Radiochemical measurement of fission product yields have provided the highest precision data for developing fission models and for nuclear forensics. The two-mode fission hypothesis provides a description of the neutron energy dependence of the mass yield curve. However, data is still rather sparse and more work is needed near second and third chance fission. Radiochemical measurements have provided evidence for the importance of nuclear states in the compound nucleus in predicting the mass yield curve in the resonance region.

  19. Development of Fission Chamber Assembly

    Institute of Scientific and Technical Information of China (English)

    YANGJinwei; ZHANGWei; SONGXianying; LIXu

    2003-01-01

    The fission chambers which are gas counters with fissile material inside chamber,provide essential information for plasma opcharacteristics. In conjunction with the neutron flux monitor system these provide time-resolved measurements of the global neutron source strength and fusion power from thermal nuclear fusion reactor as ITER for all plasma conditions for which neutrons are produced.

  20. Two neutron correlations in photo-fission

    Science.gov (United States)

    Dale, D. S.; Kosinov, O.; Forest, T.; Burggraf, J.; Stave, S.; Warren, G.; Starovoitova, V.

    2016-09-01

    A large body of experimental work has established the strong kinematical correlation between fission fragments and fission neutrons. Here, we report on the progress of investigations of the potential for strong two neutron correlations arising from the nearly back-to-back nature of the two fission fragments that emit these neutrons in the photo-fission process. In initial measurements, a pulsed electron linear accelerator was used to generate bremsstrahlung photons that impinged upon an actinide target, and the energy and opening angle distributions of coincident neutrons were measured using a large acceptance neutron detector array. A planned comprehensive set of measurements of two neutron correlations in the photo-fission of actinides is expected to shed light on several fundamental aspects of the fission process including the multiplicity distributions associated with the light and heavy fission fragments, the nuclear temperatures of the fission fragments, and the mass distribution of the fission fragments as a function of energy released. In addition to these measurements providing important nuclear data, the unique kinematics of fission and the resulting two neutron correlations have the potential to be the basis for a new tool to detect fissionable materials. A key technical challenge of this program arises from the need to perform coincidence measurements with a low duty factor, pulsed electron accelerator. This has motivated the construction of a large acceptance neutron detector array, and the development of data analysis techniques to directly measure uncorrelated two neutron backgrounds.

  1. Fission dynamics at low excitation energy

    CERN Document Server

    Aritomo, Y

    2013-01-01

    The origin of mass asymmetry in the fission of uranium at a low excitation energy is clarified by a trajectory analysis of the Langevin equation. The positions of the peaks in the mass distribution of fission fragments are mainly determined by fission saddle points originating from the shell correction energy. The widths of the peaks, on the other hand, result from a shape fluctuation around the scission point caused by the random force in the Langevin equation. We found that a random vibration in the oblate direction of fissioning fragments is essential for the fission process. According to this picture, fission does not occur with continuous stretching in the prolate direction, similarly to that observed in starch syrup. This is expected to lead to a new viewpoint of fission dynamics and the splitting mechanism.

  2. Fission yield studies at the IGISOL facility

    Energy Technology Data Exchange (ETDEWEB)

    Penttilae, H.; Elomaa, V.V.; Eronen, T.; Hakala, J.; Jokinen, A.; Kankainen, A.; Moore, I.D.; Rahaman, S.; Rinta-Antila, S.; Rissanen, J.; Saastamoinen, A.; Weber, C.; Aeystoe, J. [University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland); Rubchenya, V. [University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland); V.G. Khlopin Radium Institute, St. Petersburg (Russian Federation)

    2012-04-15

    Low-energy-particle-induced fission is a cost-effective way to produce neutron-rich nuclei for spectroscopic studies. Fission has been utilized at the IGISOL to produce isotopes for decay and nuclear structure studies, collinear laser spectroscopy and precision mass measurements. The ion guide technique is also very suitable for the fission yield measurements, which can be performed very efficiently by using the Penning trap for fission fragment identification and counting. The proton- and neutron-induced fission yield measurements at the IGISOL are reviewed, and the independent isotopic yields of Zn, Ga, Rb, Sr, Cd and In in 25MeV deuterium-induced fission are presented for the first time. Moving to a new location next to the high intensity MCC30/15 light-ion cyclotron will allow also the use of the neutron-induced fission to produce the neutron rich nuclei at the IGISOL in the future. (orig.)

  3. Delayed Fission Gamma-ray Characteristics of Th-232 U-233 U-235 U-238 and Pu-239

    Energy Technology Data Exchange (ETDEWEB)

    Lane, Taylor [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Parma, Edward J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-08-01

    Delayed fission gamma-rays play an important role in determining the time dependent ioniz- ing dose for experiments in the central irradiation cavity of the Annular Core Research Reactor (ACRR). Delayed gamma-rays are produced from both fission product decay and from acti- vation of materials in the core, such as cladding and support structures. Knowing both the delayed gamma-ray emission rate and the time-dependent gamma-ray energy spectrum is nec- essary in order to properly determine the dose contributions from delayed fission gamma-rays. This information is especially important when attempting to deconvolute the time-dependent neutron, prompt gamma-ray, and delayed gamma-ray contribution to the response of a diamond photo-conducting diode (PCD) or fission chamber in time frames of milliseconds to seconds following a reactor pulse. This work focused on investigating delayed gamma-ray character- istics produced from fission products from thermal, fast, and high energy fission of Th-232, U-233, U-235, U-238, and Pu-239. This work uses a modified version of CINDER2008, a transmutation code developed at Los Alamos National Laboratory, to model time and energy dependent photon characteristics due to fission. This modified code adds the capability to track photon-induced transmutations, photo-fission, and the subsequent radiation caused by fission products due to photo-fission. The data is compared against previous work done with SNL- modified CINDER2008 [ 1 ] and experimental data [ 2 , 3 ] and other published literature, includ- ing ENDF/B-VII.1 [ 4 ]. The ability to produce a high-fidelity (7,428 group) energy-dependent photon fluence at various times post-fission can improve the delayed photon characterization for radiation effects tests at research reactors, as well as other applications.

  4. Removal of lead by apatite and its stability in the presence of organic acids.

    Science.gov (United States)

    Katoh, Masahiko; Makimura, Akihiko; Sato, Takeshi

    2016-12-01

    In this study, lead sorption and desorption tests were conducted with apatite and organic acids (i.e. citric, malic, and formic acids) to understand lead removal by apatite in the presence of an organic acid and lead dissolution from the lead- and organic-acid-sorbed apatite by such organic acid exposure. The lead sorption test showed that the amount of lead removed by apatite in the presence of organic acid varied depending on the type of acid used. The molar amounts of calcium dissolved from apatite in the presence and absence of organic acid were exactly the same as those of lead removed even under different pH conditions as well as different organic acid concentrations, indicating that the varying amount of lead removal in the presence of different organic acids resulted from the magnitude of the dissolution of apatite and the precipitation of lead phosphate minerals. The percentages of lead dissolved from the organic-acid-sorbed and non-organic-acid-sorbed apatite by all the organic acid extractions were equal and higher than those by water extraction. In particular, the highest extractions were observed in the non-organic-acid-sorbed apatite by citric and malic acids. These results suggest that to immobilize lead by the use of apatite in the presence of organic acids, much more apatite must be added than in the absence of organic acid, and that measures must be taken to ensure that the immobilized lead is not dissolved.

  5. Synthesis and Sintering Character of Nanophase Calcium-deficient Apatite

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Nanophase calcium-deficient hydroxyapatite( CDHA ) with a Ca/P ratio about 1.5 synthesized by chemical wet method was sintered at different temperatures, and then its chemical composition, phase structure and morphology were analyzed with methods of FT- IR spectroscopy, X- ray diffraction (XRD) and field emission scanning microscopy (FESEM), respectively. Results shaw that when the sintering temperature is below 500 ℃ ,apatite crystal keeps a stable size with a diameter of 12-26 nm and a length of 30-66 nm. After being sintered at600 ℃ for 2 h, apatite crystal grows much larger with a diameter of 25-40 nm and a length of 75-100 nm. At the temperature of 700-800 ℃, this powder decomposes into Ca3 ( PO4 )2 - The crystal size of the Ca3 ( PO4 )2surpasses 200 nm in diameter and length. NH4+ ion can be removed at terrperature beyond 300 ℃ .

  6. Collagen-apatite nanocomposite membranes for guided bone regeneration.

    Science.gov (United States)

    Song, Ju-Ha; Kim, Hyoun-Ee; Kim, Hae-Won

    2007-10-01

    Collagen-apatite nanocomposite is regarded as a potential biomaterial because of its composition and structure, which are similar to those of human hard tissues. However, there have been few investigations of its mechanical and biological benefits in direct comparison with a collagen equivalent. Herein, we successfully produced a biomedical membrane made of a nanocomposite, and systemically evaluated the mechanical, chemical, and biological properties of the nanocomposite in comparison with those of pure collagen. The results showed that significant improvements were achieved by the nanocomposite approach, particularly in terms of the mechanical strength and chemical stability. The present findings point to the potential usefulness of the collagen-apatite nanocomposite membrane in the field of guided bone regeneration (GBR).

  7. Fission track Dating of Guangsi Tektite and Guangsy Paleoanthropolorcal S

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    4.11FissionTrackDatingofGuangxiTektiteandGuangxiPaleoanthropologicalSiteGuoShilun;HaoXiuhong;HuangWeiwen;ChenBaoliu(*Institut...

  8. In Situ Immobilization of Heavy Metals in Apatite Mineral Formulations

    Science.gov (United States)

    1995-04-01

    48-HOUR ADSORPTION ISOTHERMS .... 22 2.4 VERIFICATION OF PRECIPITATED METALS USING MINTEQ -A2 22 2.4.1 EXPERIMENTAL 23 2.4.2 RESULTS 23...residence time has no effect on the leaching behaviors of the metals after apatite treatment. Using the MINTEQ -A2 geochemical model, thermodynamic...speciation studies were used in the geochemical code MINTEQ to determine the stability relationships of soil minerals under varying conditions. Lead

  9. A fission fragment detector for correlated fission output studies

    Energy Technology Data Exchange (ETDEWEB)

    Mosby, S., E-mail: smosby@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Tovesson, F.; Couture, A. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Duke, D.L. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Colorado School of Mines, Golden, CO 80401 (United States); Kleinrath, V. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Idaho State University, Pocatello, ID 83201 (United States); Meharchand, R.; Meierbachtol, K.; O' Donnell, J.M.; Perdue, B.; Richman, D. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Shields, D. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Colorado School of Mines, Golden, CO 80401 (United States)

    2014-09-01

    A digital data acquisition system has been combined with a double Frisch gridded ionization chamber for use at both moderated and unmoderated neutron sources at the Los Alamos Neutron Science (LANSCE) facility. The high efficiency of the instrument combined with intense LANSCE beams and new acquisition system permits fission output measurements across 11 orders of magnitude incident neutron energy. The acquisition and analysis system is presented along with the first in-beam performance tests of the setup.

  10. Cluster fission from the standpoint of nuclear fission

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sangmoo [Tsukuba Univ., Ibaraki (Japan). Inst. of Physics

    1996-03-01

    Atomic nucleus belongs to a quantal finite many body system. Nucleus shows great resemblance to cluster, above all metal cluster, although the strength of interaction is different. The works of Brechignac group, Saunder, Martin and P. Froeblich are explained by the critical size Nc as the central term. The differences between cluster and nucleus are investigated and a future view of cluster fission is explained. (S.Y.)

  11. Status update on the NIFFTE high precision fission cross section measurement program

    Energy Technology Data Exchange (ETDEWEB)

    Laptev, Alexander B [Los Alamos National Laboratory; Tovesson, Fredrik [Los Alamos National Laboratory; Burgett, Eric [GEORGIA INSTITUTE OF TECH; Greife, Uwe [COLORADO SCHOOL OF THE MINES; Grimes, Steven [OHIO UNIV; Heffner, Michael D [LLNL; Hertel, Nolan E [GEORGIA INSTITUTE OF TECH; Hill, Tony [IDAHO NATIONAL LABORATORY; Isenhower, Donald [ABILENE CHRISTIN UNIV; Klay, Jennifer L [CALIFORNIA POLYTECHNIC STATE UNIV; Kornilov, Nickolay [OHIO UNIV; Kudo, Ryuho [CALIFORNIA POLYTECHNIC STATE UNIV; Loveland, Walter [OREGON STATE UNIV; Massey, Thomas [OHIO UNIV; Mc Grath, Chris [IDAHO NATIONAL LABORATORY; Pickle, Nathan [ABILENE CHRISTIAN UNIV; Qu, Hai [ABILENE CHRISTIAN UNIV; Sharma, Sarvagya [ABILENE CHRISTIAN UNIV; Snyder, Lucas [COLORADO SCHOOL OF THE MINES; Thornton, Tyler [ABILENE CHRISTIAN UNIV; Towell, Rusty S [ABILENE CHRISTIAN UNIV; Watson, Shon [ABILENE CHRISTIAN UNIV

    2010-01-01

    The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) program has been underway for nearly two years. The program's mission is to measure fission cross sections of the primary fissionable and fissile materials ({sup 235}U, {sup 239}Pu, {sup 238}U) as well as the minor actinides across energies from approximately 50 keV up to 20 MeV with an absolute uncertainty of less than one percent while investigating energy ranges from below an eV to 600 MeV. This basic nuclear physics data is being reinvestigated to support the next generation power plants and a fast burner reactor program. Uncertainties in the fast, resolved and unresolved resonance regions in plutonium and other transuranics are extremely large, dominating safety margins in the next generation nuclear power plants and power plants of today. This basic nuclear data can be used to support all aspects of the nuciear renaissance. The measurement campaign is utilizing a Time Projection Chamber or TPC as the tool to measure these cross sections to these unprecedented levels. Unlike traditional fission cross section measurements using time-of-flight and a multiple fission foil configurations in which fission cross sections in relation to that of {sup 235}U are performed, the TPC project uses time-of-flight and hydrogen as the benchmark cross section. Using the switch to hydrogen, a simple, smooth cross section that can be used which removes the uncertainties associated with the resolved and unresolved resonances in {sup 235}U.

  12. DSP Algorithms for Fission Fragment and Prompt Fission Neutron Spectroscopy

    Science.gov (United States)

    Zeynalova, O.; Zeynalov, Sh.; Hambsch, F.-J.; Oberstedt, S.; Fabry, I.

    2009-10-01

    Digital signal processing (DSP) algorithms are in high demand for modern nuclear fission investigation due to importance of increase the accuracy of fissile nuclear data for new generation of nuclear power stations. DSP algorithms for fission fragment (FF) and prompt fission neutron (PFN) spectroscopy are described in the present work. The twin Frisch-grid ionization chamber (GTIC) is used to measure the kinetic energy-, mass- and angular distributions of the FF in the 252Cf(SF) reaction. Along with the neutron time-of-flight (TOF) measurement the correlation between neutron emission and FF mass and energy is investigated. The TOF is measured between common cathode of the GTIC and the neutron detector (ND) pulses. Waveform digitizers (WFD) having 12 bit amplitude resolution and 100 MHz sampling frequency are used for the detector pulse sampling. DSP algorithms are developed as recursive procedures to perform the signal processing, similar to those available in various nuclear electronics modules, such as constant fraction discriminator (CFD), pulse shape discriminator (PSD), peak-sensitive analogue-to-digital converter (pADC) and pulse shaping amplifier (PSA). To measure the angle between FF and the cathode plane normal to the GTIC a new algorithm is developed having advantage over the traditional analogue pulse processing schemes. Algorithms are tested by comparing the numerical simulation of the data analysis of the 252Cf(SF) reaction with data available from literature.

  13. Formation of Ultrafine Apatite Fibers by Sol-gel/Electrospinning

    Institute of Scientific and Technical Information of China (English)

    DING Ya-mei; YUAN Xiao-yan; ZHAO Jin; GUO Wan-chun; WANG Xiu-kui

    2007-01-01

    Ultrafine apatite fibers were prepared by electrospinning of sol-gel precursor/poly(vinyl pyrrolidone)(PVP) solutions followed by subsequent calcination. The as-electrospun and calcinated fibers were observed under a scanning electron microscope and an optical polarizing microscope. Results show that the morphology and the diameter of as-electrospun fibers strongly depend on the viscosity and the surface tension of sol-gel precursor/PVP solutions. After calcination, the smooth as-electrospun fibers shrink and the fiber diameter decreases because of the removal of the polymer. The chemical evolution upon the transformation of the precursor from a gel to the final apatite fibers was investigated by thermogravimetric-differential thermal analysis, X-ray diffraction, and Fourier transform infrared spectroscopy. It is thus suggested that the crystalline structure of the calcined fibers is largely influenced by the calcination temperature. After being calcined at 600 ℃, the apatite fibers with a diameter of about 280 nm containing β-tricalcium phosphate were obtained.

  14. Fission properties for r-process nuclei

    CERN Document Server

    Erler, J; Loens, H P; Martínez-Pinedo, G; Reinhard, P -G

    2011-01-01

    We present a systematics of fission barriers and fission lifetimes for the whole landscape of super-heavy elements (SHE), i.e. nuclei with Z>100. The fission lifetimes are also compared with the alpha-decay half-lives. The survey is based on a self-consistent description in terms of the Skyrme-Hartree-Fock (SHF) approach. Results for various different SHF parameterizations are compared to explore the robustness of the predictions. The fission path is computed by quadrupole constrained SHF. The computation of fission lifetimes takes care of the crucial ingredients of the large-amplitude collective dynamics along the fission path, as self-consistent collective mass and proper quantum corrections. We discuss the different topologies of fission landscapes which occur in the realm of SHE (symmetric versus asymmetric fission, regions of triaxial fission, bi-modal fission, and the impact of asymmetric ground states). The explored region is extended deep into the regime of very neutron-rich isotopes as they are expec...

  15. Field Emission Electron Microprobe Analysis of Halogens in Apatite

    Science.gov (United States)

    Tacker, R. C.

    2011-12-01

    Field emission electron microprobe is capable of higher resolution and lower voltage than other microprobes, making it an ideal instrument for analysis of small accessory minerals in thin section such as apatite. In this study, the field emission electron microprobe was evaluated for analysis of fluorine and chlorine in apatite. Analysis was conducted on (001), (100) and an intermediate section of natural apatite crystals, using the JEOL JXA-8530F Hyperprobe, located at Fayetteville State University in Fayetteville, North Carolina. Conditions were beam current of 10 nanoamps, accelerating voltages from 5-20 kV, and spot sizes from 1-10 micrometers. Very short counting times were used, some as little as 2 seconds. Analytical strategies exploited the fact that excitation energies for fluorine Kα are much lower than for chlorine. Earlier studies (e.g. Stormer et al. 1993; Fialin and Chopin, 2006) documented the complex behavior of beam-driven migration, subsurface accumulation and desorption during fluorine analysis. The cumulative effect is increase and then fall of count rates with time and repeated analysis. The details of earlier studies were reproduced: (1) Apatite analysis by electron microprobe has two additional unknown variables, which are the crystallographic orientation of the unknown and of the standard. (2) The most reliable measure of fluorine cps is derived from a regression to zero time, accounting for crystal orientation; (3) Changing the analytical conditions (accelerating voltage, spot size, duration of analysis) changes only the time scale over which migration and desorption take place. New results from the JEOL Hyperprobe show that, for all crystal orientations, initial fluorine cps increase from 5 and 7 kV to 10 kV, but decrease systematically with further increases in kV, interpreted as loss of fluorine without concomitant excitation of X-rays. To date, fluorine analysis is routinely conducted at 15 and 20 kV. In contrast, chlorine initial

  16. The VERDI fission fragment spectrometer

    Directory of Open Access Journals (Sweden)

    Frégeau M.O.

    2013-12-01

    Full Text Available The VERDI time-of-flight spectrometer is dedicated to measurements of fission product yields and of prompt neutron emission data. Pre-neutron fission-fragment masses will be determined by the double time-of-flight (TOF technique. For this purpose an excellent time resolution is required. The time of flight of the fragments will be measured by electrostatic mirrors located near the target and the time signal coming from silicon detectors located at 50 cm on both sides of the target. This configuration, where the stop detector will provide us simultaneously with the kinetic energy of the fragment and timing information, significantly limits energy straggling in comparison to legacy experimental setup where a thin foil was usually used as a stop detector. In order to improve timing resolution, neutron transmutation doped silicon will be used. The high resistivity homogeneity of this material should significantly improve resolution in comparison to standard silicon detectors. Post-neutron fission fragment masses are obtained form the time-of-flight and the energy signal in the silicon detector. As an intermediary step a diamond detector will also be used as start detector located very close to the target. Previous tests have shown that poly-crystalline chemical vapour deposition (pCVD diamonds provides a coincidence time resolution of 150 ps not allowing complete separation between very low-energy fission fragments, alpha particles and noise. New results from using artificial single-crystal diamonds (sCVD show similar time resolution as from pCVD diamonds but also sufficiently good energy resolution.

  17. Bone-like apatite layer formation on the new resin-modified glass-ionomer cement.

    Science.gov (United States)

    Nourmohammadi, Jhamak; Sadrnezhaad, S K; Ghader, A Behnam

    2008-12-01

    In this study, the apatite-forming ability of the new resin-modified glass-ionomer cement was evaluated by soaking the cement in the simulated body fluid. The Fourier Transform Infrared (FTIR) spectrometer and X-Ray Diffraction (XRD) patterns of the soaked cement pointed to the creation of poorly crystalline carbonated apatite. It was found that the releasing of calcium ions from the soaked cement will dominate the undesirable effect of polyacrylic acid on apatite formation. Consequently, the ionic activity products (IAPs) of the apatite in the surrounding medium increased which accelerated apatite nucleation induced by the presence of the Si-OH and COOH groups. Accordingly, the apatite nuclei started to form via primary heterogeneous nucleation and continued by secondary nucleation. Therefore, nucleation and growth occurs as in the layer-by-layer mode so that finite numbers of monolayers are produced. Subsequent formation of film occurs by formation of discrete nuclei (layer-plus-island or SK growth).

  18. Technical Application of Nuclear Fission

    Science.gov (United States)

    Denschlag, J. O.

    The chapter is devoted to the practical application of the fission process, mainly in nuclear reactors. After a historical discussion covering the natural reactors at Oklo and the first attempts to build artificial reactors, the fundamental principles of chain reactions are discussed. In this context chain reactions with fast and thermal neutrons are covered as well as the process of neutron moderation. Criticality concepts (fission factor η, criticality factor k) are discussed as well as reactor kinetics and the role of delayed neutrons. Examples of specific nuclear reactor types are presented briefly: research reactors (TRIGA and ILL High Flux Reactor), and some reactor types used to drive nuclear power stations (pressurized water reactor [PWR], boiling water reactor [BWR], Reaktor Bolshoi Moshchnosti Kanalny [RBMK], fast breeder reactor [FBR]). The new concept of the accelerator-driven systems (ADS) is presented. The principle of fission weapons is outlined. Finally, the nuclear fuel cycle is briefly covered from mining, chemical isolation of the fuel and preparation of the fuel elements to reprocessing the spent fuel and conditioning for deposit in a final repository.

  19. Fusion-Fission Hybrid for Fissile Fuel Production without Processing

    Energy Technology Data Exchange (ETDEWEB)

    Fratoni, M; Moir, R W; Kramer, K J; Latkowski, J F; Meier, W R; Powers, J J

    2012-01-02

    Two scenarios are typically envisioned for thorium fuel cycles: 'open' cycles based on irradiation of {sup 232}Th and fission of {sup 233}U in situ without reprocessing or 'closed' cycles based on irradiation of {sup 232}Th followed by reprocessing, and recycling of {sup 233}U either in situ or in critical fission reactors. This study evaluates a third option based on the possibility of breeding fissile material in a fusion-fission hybrid reactor and burning the same fuel in a critical reactor without any reprocessing or reconditioning. This fuel cycle requires the hybrid and the critical reactor to use the same fuel form. TRISO particles embedded in carbon pebbles were selected as the preferred form of fuel and an inertial laser fusion system featuring a subcritical blanket was combined with critical pebble bed reactors, either gas-cooled or liquid-salt-cooled. The hybrid reactor was modeled based on the earlier, hybrid version of the LLNL Laser Inertial Fusion Energy (LIFE1) system, whereas the critical reactors were modeled according to the Pebble Bed Modular Reactor (PBMR) and the Pebble Bed Advanced High Temperature Reactor (PB-AHTR) design. An extensive neutronic analysis was carried out for both the hybrid and the fission reactors in order to track the fuel composition at each stage of the fuel cycle and ultimately determine the plant support ratio, which has been defined as the ratio between the thermal power generated in fission reactors and the fusion power required to breed the fissile fuel burnt in these fission reactors. It was found that the maximum attainable plant support ratio for a thorium fuel cycle that employs neither enrichment nor reprocessing is about 2. This requires tuning the neutron energy towards high energy for breeding and towards thermal energy for burning. A high fuel loading in the pebbles allows a faster spectrum in the hybrid blanket; mixing dummy carbon pebbles with fuel pebbles enables a softer spectrum in

  20. Determination of Uranium in Apatite Minerals by Solvent Extraction--Inductively Coupled Plasma Atomic Emission Spectrometry

    OpenAIRE

    1993-01-01

    [Abstract] Solvent, extraction-ICP atomic emission spectrometry was applied to the determination of uranium in apatite minerals. Apatite minerals were treated with nitric acid. After removing a small quantity of insoluble residue, uranium was extracted with 0.05 mol/dm^3 1-phonyl-3-mcthyl-4-trifluoroacetyl-5-pyrazolonc-diisobutyl kctone at pH 0.8. The uranium content in the apatite was found to be (20.3〜132.9)×10^%.

  1. 10 Towards a Safer Environment:(7)How apatite minerals remediate Pb, Zn and Mn from wastewater?

    Institute of Scientific and Technical Information of China (English)

    Samy Mohamed Abdallah

    2010-01-01

    To evaluate the effectiveness of apatite mineral in removing different contaminants from low quality water in the industrial city of abha,Asir region,southwestern of Saudi Arabia two phosphatic clay dominated by apatite mineral were selected.In situ remediation experiment proved that apatite mineral has the highest affinity for Pb and removed more than 94% from initial Pb concentration.The rest of contaminants followed the descending order of:Zn>Mn>Cu>Co>Ni.The sorption of Pb,Zn and Mn onto apatite mineral was well characterized by the Langmuir model.Ternary-metal addition induced competitive sorption among the three metals,with the interfering effect of Pb>Zn>Mn.Durlng metal retention by apatite mineral calcium and phosphate were determined in equilibrium solution.Calcium increased and phosphate decreased with increasing metal disappearance.The greatest increase of calcium and the largest phosphate reduction were found with Pb+2 sorption.This is suggested that Pb+2 retention by apatite was through the dissolution of apatite which mean release of Ca and P into solution and formation of pyromorphite(lead phosphate)as consuming of P.Obtained results suggested that there are two general mechanisms for the ability of apatite mineral to fake up Pb2+,Zn+2 and Mn+2.The first is(ion-ion exchange mechanism)concerned with adsorption of ions on the solid surface followed by their diffusion into apatite mineral and the release of cations originally contained within apatite.The second is(dissolution-precipitation mechanism)concerned to the dissolution of apatite in the aqueous solution containing Pb2+,Zn+2 and Mn+2 followed by the precipitation or coprecipitation.Pb+2 desorption responding to solution pH may indicate that not all the Pb+2 was chemisorbed and fraction of Pb+2 was weakly adsorbed or complexed on the surface of apatite mineral.

  2. Radiochemical studies on nuclear fission at Trombay

    Indian Academy of Sciences (India)

    Asok Goswami

    2015-08-01

    Since the discovery of nuclear fission in the year 1939, both physical and radiochemical techniques have been adopted for the study of various aspects of the phenomenon. Due to the ability to separate individual elements from a complex reaction mixture with a high degree of sensitivity and selectivity, a chemist plays a significant role in the measurements of mass, charge, kinetic energy, angular momentum and angular distribution of fission products in various fissioning systems. At Trombay, a small group of radiochemists initiated the work on radiochemical studies of mass distribution in the early sixties. Since then, radiochemical investigations on various fission observables have been carried out at Trombay in , , and heavy-ion-induced fissions. An attempt has been made to highlight the important findings of such studies in this paper, with an emphasis on medium energy and heavy-ion-induced fission.

  3. Collective spectra along the fission barrier

    Directory of Open Access Journals (Sweden)

    Pigni M. T.

    2012-12-01

    Full Text Available Discrete and continuous spectra of fissioning nuclei at the humps of fission barriers (Bohr transition states and in the intermediate wells (superdeformed and hyperdeformed states play a key role in the calculation of fission cross sections. A theoretical evaluation of the collective parts of the spectra is possible within the framework of the dinuclear system model, which treats the wave function of the fissioning nucleus as a superposition of a mononucleus configuration and two–cluster configurations in a dynamical way, permitting exchange of upper–shell nucleons between clusters. The impact of theoretical spectra on neutron–induced fission cross sections and, in combination with an improved version of the scission–point model, on angular distribution of fission fragments is evaluated for plutonium isotopes of interest to nuclear energy applications.

  4. Comparative evaluation of solar, fission, fusion, and fossil energy resources. Part 2: Power from nuclear fission

    Science.gov (United States)

    Clement, J. D.

    1973-01-01

    Different types of nuclear fission reactors and fissionable materials are compared. Special emphasis is placed upon the environmental impact of such reactors. Graphs and charts comparing reactor facilities in the U. S. are presented.

  5. Fission dynamics within time-dependent Hartree-Fock: deformation-induced fission

    CERN Document Server

    Goddard, P M; Rios, A

    2015-01-01

    Background: Nuclear fission is a complex large-amplitude collective decay mode in heavy nuclei. Microscopic density functional studies of fission have previously concentrated on adiabatic approaches based on constrained static calculations ignoring dynamical excitations of the fissioning nucleus, and the daughter products. Purpose: To explore the ability of dynamic mean-field methods to describe fast fission processes beyond the fission barrier, using the nuclide $^{240}$Pu as an example. Methods: Time-dependent Hartree-Fock calculations based on the Skyrme interaction are used to calculate non-adiabatic fission paths, beginning from static constrained Hartree-Fock calculations. The properties of the dynamic states are interpreted in terms of the nature of their collective motion. Fission product properties are compared to data. Results: Parent nuclei constrained to begin dynamic evolution with a deformation less than the fission barrier exhibit giant-resonance-type behaviour. Those beginning just beyond the ...

  6. Characterization of antiseptic apatite powders prepared at biomimetics temperature and pH

    Directory of Open Access Journals (Sweden)

    Soumia Belouafa

    2008-03-01

    Full Text Available Antiseptic apatite-based calcium phosphates were prepared as the single-phase powders. Phosphocalcic oxygenated apatites were synthesized from calcium salts and orthophosphate dissolved in oxygenated water solution at 30%, under the biomimetic conditions of 37 °C and pH 7.4. The characterization and chemical analysis of the synthesized biomimetic apatite powders were performed by scanning electron microscopy (SEM, powder X ray diffraction (XRD, Fourier-transformed infrared spectroscopy (FT-IR and chemical analysis. The obtained materials are a calcium deficient apatites with different morphologies.

  7. Molecular functionalization of tantalum oxide surface towards development of apatite growth

    Energy Technology Data Exchange (ETDEWEB)

    Aubry, D. [Laboratory of Chemistry and Electrochemistry of Surfaces (CES), University of Namur, FUNDP, Rue de Bruxelles 61, B-5000 Namur (Belgium); Volcke, C. [Research Center in Physics of Matter and Radiation (PMR), University of Namur, FUNDP, Rue de Bruxelles 61, B-5000 Namur (Belgium); Arnould, Ch. [Laboratory of Chemistry and Electrochemistry of Surfaces (CES), University of Namur, FUNDP, Rue de Bruxelles 61, B-5000 Namur (Belgium); Humbert, C.; Thiry, P.A. [Research Center in Physics of Matter and Radiation (PMR), University of Namur, FUNDP, Rue de Bruxelles 61, B-5000 Namur (Belgium); Delhalle, J. [Laboratory of Chemistry and Electrochemistry of Surfaces (CES), University of Namur, FUNDP, Rue de Bruxelles 61, B-5000 Namur (Belgium); Mekhalif, Z., E-mail: zineb.mekhalif@fundp.ac.be [Laboratory of Chemistry and Electrochemistry of Surfaces (CES), University of Namur, FUNDP, Rue de Bruxelles 61, B-5000 Namur (Belgium)

    2009-02-15

    We have studied the apatite growth dynamics on tantalum oxide surfaces. This nucleation is obtained via an organosilane intermediate layer between the apatite and the substrate surface. Four organosilane layers (differing by their terminal functionality) were investigated. Their characterization with atomic force microscopy and other techniques such as X-ray photoelectron spectroscopy (XPS) and wetting measurements highlighted the influence of the organosilane terminal groups on the apatite growth rates. Results revealed that apatite is indeed growing faster on phosphate terminal groups than on the three other groups studied (vinyl, hydroxyl and carboxyl).

  8. Molecular functionalization of tantalum oxide surface towards development of apatite growth

    Science.gov (United States)

    Aubry, D.; Volcke, C.; Arnould, Ch.; Humbert, C.; Thiry, P. A.; Delhalle, J.; Mekhalif, Z.

    2009-02-01

    We have studied the apatite growth dynamics on tantalum oxide surfaces. This nucleation is obtained via an organosilane intermediate layer between the apatite and the substrate surface. Four organosilane layers (differing by their terminal functionality) were investigated. Their characterization with atomic force microscopy and other techniques such as X-ray photoelectron spectroscopy (XPS) and wetting measurements highlighted the influence of the organosilane terminal groups on the apatite growth rates. Results revealed that apatite is indeed growing faster on phosphate terminal groups than on the three other groups studied (vinyl, hydroxyl and carboxyl).

  9. Biomimetic nanocrystalline apatite coatings synthesized by Matrix Assisted Pulsed Laser Evaporation for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Visan, A. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Grossin, D. [CIRIMAT – Carnot Institute, University of Toulouse, ENSIACET, 4 Allée Emile Monso, 31030 Toulouse Cedex 4 (France); Stefan, N.; Duta, L.; Miroiu, F.M. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Stan, G.E. [National Institute of Materials Physics, RO-077125, Magurele-Ilfov (Romania); Sopronyi, M.; Luculescu, C. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Freche, M.; Marsan, O.; Charvilat, C. [CIRIMAT – Carnot Institute, University of Toulouse, ENSIACET, 4 Allée Emile Monso, 31030 Toulouse Cedex 4 (France); Ciuca, S. [Politehnica University of Bucharest, Faculty of Materials Science and Engineering, Bucharest (Romania); Mihailescu, I.N., E-mail: ion.mihailescu@inflpr.ro [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania)

    2014-02-15

    Highlights: • We report the deposition by MAPLE of biomimetic apatite coatings on Ti substrates. • This is the first report of MAPLE deposition of hydrated biomimetic apatite films. • Biomimetic apatite powder was synthesized by double decomposition process. • Non-apatitic environments, of high surface reactivity, are preserved post-deposition. • We got the MAPLE complete transfer as thin film of a hydrated, delicate material. -- Abstract: We report the deposition by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique of biomimetic nanocrystalline apatite coatings on titanium substrates, with potential application in tissue engineering. The targets were prepared from metastable, nanometric, poorly crystalline apatite powders, analogous to mineral bone, synthesized through a biomimetic approach by double decomposition process. For the deposition of thin films, a KrF* excimer laser source was used (λ = 248 nm, τ{sub FWHM} ≤ 25 ns). The analyses revealed the existence, in synthesized powders, of labile non-apatitic mineral ions, associated with the formation of a hydrated layer at the surface of the nanocrystals. The thin film analyses showed that the structural and chemical nature of the nanocrystalline apatite was prevalently preserved. The perpetuation of the non-apatitic environments was also observed. The study indicated that MAPLE is a suitable technique for the congruent transfer of a delicate material, such as the biomimetic hydrated nanohydroxyapatite.

  10. Fission-product retention in HTGR fuels

    Energy Technology Data Exchange (ETDEWEB)

    Homan, F.J.; Kania, M.J.; Tiegs, T.N.

    1982-01-01

    Retention data for gaseous and metallic fission products are presented for both Triso-coated and Biso-coated HTGR fuel particles. Performance trends are established that relate fission product retention to operating parameters, such as temperature, burnup, and neutron exposure. It is concluded that Biso-coated particles are not adequately retentive of fission gas or metallic cesium, and Triso-coated particles which retain cesium still lose silver. Design implications related to these performance trends are identified and discussed.

  11. Rapid Separation of Fission Product 141La

    Institute of Scientific and Technical Information of China (English)

    XIA; Wen; YE; Hong-sheng; LIN; Min; CHEN; Ke-sheng; XU; Li-jun; ZHANG; Wei-dong; CHEN; Yi-zhen

    2013-01-01

    141La was separated and purified from fission products in this work for physical measurements aimed at improving the accuracy of its decay parameters.As the impact of 142La and other fission products,cesium(141Cs,142Cs included)was rapid separated from the fission products,141Cs and 142Ba separation was prepared after a cooling time about 25 s when 142Cs decays to daughter 142Ba,141La purification then

  12. Fission Product Decay Heat Calculations for Neutron Fission of 232Th

    Science.gov (United States)

    Son, P. N.; Hai, N. X.

    2016-06-01

    Precise information on the decay heat from fission products following times after a fission reaction is necessary for safety designs and operations of nuclear-power reactors, fuel storage, transport flasks, and for spent fuel management and processing. In this study, the timing distributions of fission products' concentrations and their integrated decay heat as function of time following a fast neutron fission reaction of 232Th were exactly calculated by the numerical method with using the DHP code.

  13. Effect of nuclear viscosity on fission process

    Energy Technology Data Exchange (ETDEWEB)

    Li Shidong; Kuang Huishun; Zhang Shufa; Xing Jingru; Zhuo Yizhong; Wu Xizhen; Feng Renfa

    1989-02-01

    According to the fission diffusion model, the deformation motion of fission nucleuses is regarded as a diffusion process of quasi-Brownian particles under fission potential. Through simulating such Brownian motion in two dimensional phase space by Monte-Carlo mehtod, the effect of nuclear visocity on Brownian particle diffusion is studied. Dynamical quanties, such as fission rate, kinetic energy distribution on scission, and soon are numerically calculated for various viscosity coefficients. The results are resonable in physics. This method can be easily extended to deal with multi-dimensional diffusion problems.

  14. Theoretical Description of the Fission Process

    Energy Technology Data Exchange (ETDEWEB)

    Witold Nazarewicz

    2003-07-01

    The main goals of the project can be summarized as follows: Development of effective energy functionals that are appropriate for the description of heavy nuclei. Our goal is to improve the existing energy density (Skyrme) functionals to develop a force that will be used in calculations of fission dynamics. Systematic self-consistent calculations of binding energies and fission barriers of actinide and trans-actinide nuclei using modern density functionals. This will be followed by calculations of spontaneous fission lifetimes and mass and charge divisions using dynamic adiabatic approaches based on the WKB approximation. Investigate novel microscopic (non-adiabatic) methods to study the fission process.

  15. Some aspects of fission and quasifission processes

    Indian Academy of Sciences (India)

    B B Back

    2015-08-01

    The discovery of nuclear fission in 1938–1939 had a profound influence on the field of nuclear physics and it brought this branch of physics into the forefront as it was recognized for having the potential for its seminal influence on modern society. Although many of the basic features of actinide fission were described in a ground-breaking paper by Bohr and Wheeler only six months after the discovery, the fission process is very complex and it has been a challenge for both experimentalists and theorists to achieve a complete and satisfactory understanding of this phenomenon. Many aspects of nuclear physics are involved in fission and it continues to be a subject of intense study even three quarters of a century after its discovery. In this talk, I will review an incomplete subset of the major milestones in fission research, and briefly discuss some of the topics that I have been involved in during my career. These include studies of vibrational resonances and fission isomers that are caused by the second minimum in the fission barrier in actinide nuclei, studies of heavy-ion-induced fission in terms of the angular distributions and the mass–angle correlations of fission fragments. Some of these studies provided evidence for the importance of the quasifission process and the attendant suppression of the complete fusion process. Finally, some of the circumstances around the establishment of large-scale nuclear research in India will be discussed.

  16. Roundness of heavy minerals (zircon and apatite) as a provenance tool for unraveling recycling: A case study from the Sefidrud and Sarbaz rivers in N and SE Iran

    Science.gov (United States)

    Zoleikhaei, Yousef; Frei, Dirk; Morton, Andrew; Zamanzadeh, S. Mohammad

    2016-08-01

    In order to improve techniques for provenance studies, and especially to address the question of sediment recycling, morphological changes of two minerals with contrasting durability (zircon and apatite) were tracked during both fluvial transport and littoral reworking. The Sefidrud river system in northern Iran, which drains the Alborz volcano-sedimentary range into the Caspian Sea, and the Sarbaz river system in southeastern Iran, which drains the Makran Accretionary Prism into the Oman Sea, were chosen for this study. To determine source rocks of the grains, and thus their nature in terms of sedimentary cycles, zircon geochronology was conducted on both rivers. The zircon data indicate that most of the Sefidrud sediments are first cycle, derived from crystalline rocks, and the Sarbaz sediments are generally recycled from older wedges of the Makran. Results from SEM analysis show significant differences between the roundness of associated zircon and apatite grains. Zircon grains remain unrounded through several cycles, while apatite grains show abrasion from the early stages of their first cycle.

  17. Evaluation of apatite silicates as solid oxide fuel cell electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Marrero-Lopez, D. [Dpto. de Fisica Aplicada I, Laboratorio de Materiales y Superficies (Unidad Asociada al C.S.I.C.), Universidad de Malaga, 29071 Malaga (Spain); Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Martin-Sedeno, M.C.; Aranda, M.A.G. [Dpto. de Quimica Inorganica, Universidad Malaga, 29071 Malaga (Spain); Pena-Martinez, J. [Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Instituto de Energias Renovables, Parque Tecnologico, Universidad de Castilla La Mancha, 02006 Albacete (Spain); Ruiz-Morales, J.C.; Nunez, P. [Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Ramos-Barrado, J.R. [Dpto. de Fisica Aplicada I, Laboratorio de Materiales y Superficies (Unidad Asociada al C.S.I.C.), Universidad de Malaga, 29071 Malaga (Spain)

    2010-05-01

    Apatite-type silicates have been considered as promising electrolytes for Solid Oxide Fuel Cells (SOFC); however studies on the potential use of these materials in SOFC devices have received relatively little attention. The lanthanum silicate with composition La{sub 10}Si{sub 5.5}Al{sub 0.5}O{sub 26.75} has been evaluated as electrolyte with the electrode materials commonly used in SOFC, i.e. manganite, ferrite and cobaltite as cathode materials and NiO-CGO composite, chromium-manganite and Sr{sub 2}MgMoO{sub 6} as anode materials. Chemical compatibility, area-specific resistance and fuel cell studies have been performed. X-ray powder diffraction (XRPD) analysis did not reveal any trace of reaction products between the apatite electrolyte and most of the aforementioned electrode materials. However, the area-specific polarisation resistance (ASR) of these electrodes in contact with apatite electrolyte increased significantly with the sintering temperature, indicating reactivity at the electrolyte/electrode interface. On the other hand, the ASR values are significantly improved using a ceria buffer layer between the electrolyte and electrode materials to prevent reactivity. Maximum power densities of 195 and 65 mWcm{sup -2} were obtained at 850 and 700 C, respectively in H{sub 2} fuel, using an 1 mm-thick electrolyte, a NiO-Ce{sub 0.8}Gd{sub 0.2}O{sub 1.9} composite as anode and La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} as cathode materials. This fuel cell was tested for 100 h in 5%H{sub 2}-Ar atmosphere showing stable performance. (author)

  18. Isoscaling of the Fission Fragments with Langevin Equation

    Institute of Scientific and Technical Information of China (English)

    WANG Kun; TIAN Wen-Dong; ZHONG Chen; ZHOU Xing-Fei; MA Yu-Gang; WEI Yi-Bin; CAI Xiang-Zhou; CHEN Jin-Gen; FANG De-Qing; GUO Wei; MA Guo-Liang; SHEN Wen-Qing

    2005-01-01

    @@ The Langevin equation is used to simulate the fission process of 112Sn + 112Sn and 116Sn + 116Sn. The mass distribution of the fission fragments are given by assuming the process of symmetric fission or asymmetric fission with the Gaussian probability sampling. The isoscaling behaviour has been observed from the analysis of fission fragments of both the reactions, and the isoscaling parameter α seems to be sensitive to the width of fission probability and the beam energy.

  19. Spectroscopy of heavy fissionable nuclei

    Indian Academy of Sciences (India)

    S K Tandel

    2015-09-01

    Structural studies of heavy nuclei are quite challenging due to increased competition from fission, particularly at high spins. Nuclei in the actinide region exhibit a variety of interesting phenomena. Recent advances in instrumentation and analysis techniques have made feasible sensitive measurements of nuclei populated with quite low cross-sections. These include isomers and rotational band structures in isotopes of Pu ( = 94) to Rf ( = 104), and octupole correlations in the Th ( = 90) region. The obtained experimental data have provided insights on various aspects like moments of inertia and nucleon alignments at high spins, quasiparticle energies and evolution of quadrupole and octupole collectivity, among others. An overview of some of these results is presented.

  20. Nuclear Power from Fission Reactors. An Introduction.

    Science.gov (United States)

    Department of Energy, Washington, DC. Technical Information Center.

    The purpose of this booklet is to provide a basic understanding of nuclear fission energy and different fission reaction concepts. Topics discussed are: energy use and production, current uses of fuels, oil and gas consumption, alternative energy sources, fossil fuel plants, nuclear plants, boiling water and pressurized water reactors, the light…

  1. Prompt fission neutron spectrum of actinides

    Energy Technology Data Exchange (ETDEWEB)

    Capote, R. [International Atomic Energy Agency, Vienna (Austria); Chen, Y. -J. [China Institute of Atomic Energy, Beijing (China); Hambsch, F. J. [European Commission, Joint Research Centre - IRRM, Geel (Belgium); Jurado, B. [CENBG, CNRS/IN2P3, Gradignan (France); Kornilov, N. [Ohio Univ., Athens, OH (United States); Lestone, J. P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Litaize, O. [CEA, DEN, DER, SPRC, Saint-Paul-Lez-Durance (France); Morillon, B. [CEA, DAM, DIF, Arpajon (France); Neudecker, D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oberstedt, S. [European Commission, Joint Research Centre - IRRM, Geel (Belgium); Ohsawa, T. [Kinki Univ., Osaka-fu (Japan); Otuka, N. [International Atomic Energy Agency, Vienna (Austria); Pronyaev, V. G. [Institute of Physics and Power Engineering, Obninsk (Russian Federation); Saxena, A. [Bhabha Atomic Research Centre, Mumbai (India); Schmidt, K. H. [CENBG, CNRS/IN2P3, Gradignan (France); Serot, O. [CEA, DEN, DER, SPRC, Saint-Paul-Lez-Durance (France); Shcherbakov, O. A. [Petersburg Nuclear Physics Institute of NRC " Kurchatov Institute" , Gatchina (Russian Federation); Shu, N. -C. [China Institute of Atomic Energy, Beijing (China); Smith, D. L. [Argonne National Lab. (ANL), Argonne, IL (United States); Talou, P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Trkov, A. [International Atomic Energy Agency, Vienna (Austria); Tudora, A. C. [Univ. of Bucharest, Magurele (Romania); Vogt, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of California, Davis, CA (United States); Vorobyev, A. S. [Petersburg Nuclear Physics Institute of NRC " Kurchatov Institute" , Gatchina (Russian Federation)

    2016-01-06

    Here, the energy spectrum of prompt neutron emitted in fission (PFNS) plays a very important role in nuclear science and technology. A Coordinated Research Project (CRP) "Evaluation of Prompt Fission Neutron Spectra of Actinides" was established by the IAEA Nuclear Data Section in 2009, with the major goal to produce new PFNS evaluations with uncertainties for actinide nuclei.

  2. Correlation measurements of fission-fragment properties

    Directory of Open Access Journals (Sweden)

    Oberstedt A.

    2010-10-01

    Full Text Available For the development of future nuclear fission applications and for a responsible handling of nuclear waste the a-priori assessment of the fission-fragments’ heat production and toxicity is a fundamental necessity. The success of an indispensable modelling of the fission process strongly depends on a good understanding of the particular mechanism of scission, the mass fragmentation and partition of excitation energy. Experimental observables are fission-fragment properties like mass- and energy-distributions, and the prompt neutron as well as γ-ray multiplicities and emission spectra. The latter quantities should preferably be known as a function of fragment mass and excitation energy. Those data are highly demanded as published by the OECD-NEA in its high priority data request list. With the construction of the double (v, E spectrometer VERDI we aim at measuring pre- and post-neutron masses directly and simultaneously to avoid prompt neutron corrections. From the simultaneous measurement of pre- and post-neutron fission-fragment data the prompt neutron multiplicity may then be inferred fully correlated with fragment mass yield and total kinetic energy. Using an ultra-fast fission event trigger spectral prompt fission γ-ray measurements may be performed. For that purpose recently developed lanthanum-halide detectors, with excellent timing characteristics, were coupled to the VERDI spectrometer allowing for a very good discrimination of fission γ-rays and prompt neutrons due to their different time-of-flight.

  3. Study of Thermal Activated CO2 Extraction Processes from Carbonate Apatites Using Gas Chromatography

    Directory of Open Access Journals (Sweden)

    V.N. Kuznetsov

    2015-10-01

    Full Text Available The study of carbonate in the structure of carbonate-containing apatites (CCA is an actual problem due to the similarity of such systems to natural apatites of mammalian bone tissue. The search of the optimal synthesis procedures was also carried out in order to obtain carbonate apatites with the highest rate of carbonate ions incorporation into the apatite structure. The analysis of carbonate-group temperature behavior in apatites of various origin helps to understand their structural and functional roles in biologically relevant apatite materials. The thermal extraction and accumulation of CO2 from biogenic and geological apatites is also of interest for the further carbon isotope analysis with accelerating mass-spectrometry. X-ray diffraction analysis, infrared spectroscopy and scanning electron microscopy as well as self-proposed gas chromatography method with thermo-programmed probe extraction were used for carbonate temperature behavior study. This new method allows determining CO2 concentration released from CCA during annealing. The defined changes in carbonate apatite structure depending on synthesis procedure were observed.

  4. Influence of local charge compensation on site occupation and luminescence of apatites

    NARCIS (Netherlands)

    Blasse, G.

    1975-01-01

    The apatite structure contains two different sites for the larger cations. It is shown that the principle of local charge compensation can predict the site occupation. This is especially important for an interpretation of the luminescence properties of a number of apatites. The predictions are compa

  5. Behaviour of apatite during partial melting of metapelites and consequences for prograde suprasolidus monazite growth

    Science.gov (United States)

    Yakymchuk, Chris

    2017-03-01

    The suprasolidus behaviour of apatite and monazite is examined for an average metapelite composition using phase equilibria modelling coupled with solubility equations of these minerals. Both closed- and open-system scenarios are considered. Partial melting above the solidus requires apatite and monazite breakdown in order to saturate the anatectic melt in phosphorus and the light rare earth elements. In general, melt loss is predicted to increase the stability of apatite and monazite at high temperature. Most apatite is predicted to survive up to ultrahigh temperature conditions except for rocks with low bulk phosphorus concentrations. By contrast, most monazite is expected to be consumed by UHT conditions. Thorium substitution in monazite is expected to increase the stability of monazite to higher temperatures. The presence of LREE-rich apatite decreases the stability of monazite above the solidus, but the breakdown of this apatite during anatexis may generate prograde monazite at the apatite-melt interface in local pockets of melt oversaturation. However, prograde suprasolidus monazite along grain boundaries is expected to be consumed during further partial melting or during melt homogenization when an interconnected melt network develops. Anatectic melts are predicted to be saturated with respect to apatite except at UHT conditions and for rocks with low initial P2O5 bulk concentrations.

  6. Heterotopic bone formation by nano-apatite conraining poly (D,L-lactide)composites

    NARCIS (Netherlands)

    Barbieri, D.; Renard, A.J.S.; Bruijn, de J.D.; Yuan, H.

    2010-01-01

    To render polymeric materials osteoinductive, nano-sized calcium phosphate apatite particles (CaP) were introduced into a low molecular weight poly(D,L-lactide). Homogenous composites were made with 10%, 20% and 40% by weight of apatite content while pure polylactide was used as control. Thereafter

  7. Effects of apatite particle size in two apatite/collagen composites on the osteogenic differentiation profile of osteoblastic cells

    OpenAIRE

    HATAKEYAMA, WATARU; TAIRA, Masayuki; Chosa, Naoyuki; KIHARA, HIDEMICHI; ISHISAKI,Akira; KONDO, HISATOMO

    2013-01-01

    The development of new osteoconductive bone substitute materials is expected in medicine. In this study, we attempted to produce new hydroxylapatite (HAP)/collagen (Col) composites using two HAP particles of different sizes and porcine type I collagen. The two HAP particles were either nano-sized (40 nm in average diameter; n-HAP) or had macro-pore sizes of 0.5–1.0 mm in length with fully interconnected pores (m-HAP). The aim of this study was to investigate the effects of apatite particle si...

  8. Theoretical Description of the Fission Process

    Energy Technology Data Exchange (ETDEWEB)

    Witold Nazarewicz

    2009-10-25

    Advanced theoretical methods and high-performance computers may finally unlock the secrets of nuclear fission, a fundamental nuclear decay that is of great relevance to society. In this work, we studied the phenomenon of spontaneous fission using the symmetry-unrestricted nuclear density functional theory (DFT). Our results show that many observed properties of fissioning nuclei can be explained in terms of pathways in multidimensional collective space corresponding to different geometries of fission products. From the calculated collective potential and collective mass, we estimated spontaneous fission half-lives, and good agreement with experimental data was found. We also predicted a new phenomenon of trimodal spontaneous fission for some transfermium isotopes. Our calculations demonstrate that fission barriers of excited superheavy nuclei vary rapidly with particle number, pointing to the importance of shell effects even at large excitation energies. The results are consistent with recent experiments where superheavy elements were created by bombarding an actinide target with 48-calcium; yet even at high excitation energies, sizable fission barriers remained. Not only does this reveal clues about the conditions for creating new elements, it also provides a wider context for understanding other types of fission. Understanding of the fission process is crucial for many areas of science and technology. Fission governs existence of many transuranium elements, including the predicted long-lived superheavy species. In nuclear astrophysics, fission influences the formation of heavy elements on the final stages of the r-process in a very high neutron density environment. Fission applications are numerous. Improved understanding of the fission process will enable scientists to enhance the safety and reliability of the nation’s nuclear stockpile and nuclear reactors. The deployment of a fleet of safe and efficient advanced reactors, which will also minimize radiotoxic

  9. Fission dynamics at low excitation energy. 2

    CERN Document Server

    Aritomo, Y; Ivanyuk, F A

    2014-01-01

    The mass asymmetry in the fission of U-236 at low excitation energy is clarified by the analysis of the trajectories obtained by solving the Langevin equations for the shape degrees of freedom. It is demonstrated that the position of the peaks in the mass distribution of fission fragments is determined mainly by the saddle point configuration originating from the shell correction energy. The width of the peaks, on the other hand, results from the shape fluctuations close to the scission point caused by the random force in the Langevin equation. We have found out that the fluctuations between elongated and compact shapes are essential for the fission process. According to our results the fission does not occur with continuous stretching in the prolate direction, similarly to that observed in starch syrup, but is accompanied by the fluctuations between elongated and compact shapes. This picture presents a new viewpoint of fission dynamics and the splitting mechanism.

  10. Cold fission as heavy ion emission

    Energy Technology Data Exchange (ETDEWEB)

    Poenaru, D.N.; Maruhn, J.A.; Greiner, W.; Ivascu, M.; Mazilu, D.; Gherghescu, R.

    1987-11-01

    The last version of the analytical superasymmetric fission model is applied to study cold fission processes. Strong shell effects are present either in one or both fission fragments. A smooth behaviour is observed when the proton or the neutron numbers are changed by four units. Increasing Z and N, in the transuranium region, a sharp transition from asymmetry with a large peak-to-valley ratio to symmetry at Z=100 and/or N=164 is obtained. The transition toward asymmetry at higher Z and N is much smoother. The most probable cold fission light fragments from /sup 234/U, /sup 236/U, /sup 239/Np and /sup 240/Pu are /sup 100/Zr, /sup 104/Mo, /sup 106/Mo and /sup 106/Mo, respectively, in good agreement with experimental data. The unified treatment of alpha decay, heavy ion radioactivities and cold fission is illustrated for /sup 234/U - the first nucleus in which all three groups have been already observed.

  11. Los Alamos National Laboratory Fission Basis

    Energy Technology Data Exchange (ETDEWEB)

    Keksis, A.L.; Chadwick, M.B.; Selby, H.D.; Mac Innes, M.R.; Barr, D.W.; Meade, R.A.; Burns, C.J.; Wallstrom, T.C. [Los Alamos National Laboratory, NM 87545 (United States)

    2011-07-01

    This report is an overview of two main publications that provide a comprehensive review of the Los Alamos National Laboratory (LANL) Fission Basis. The first is the experimental paper, {sup F}ission Product Data Measured at Los Alamos for Fission Spectrum and Thermal Neutrons on {sup 239}Pu, {sup 235}U, {sup 238}U, [Selby, H. D., et al., Nucl. Data Sheets, Vol. 111 2010, pp. 2891-2922] and the second is the theoretical paper, Fission Product Yields from Fission Spectrum n+ {sup 239}Pu for ENDF/B-VII.1, [Chadwick, M. B., et al., Nucl. Data Sheets, Vol. 111, 2010, pp. 2923-2964]. One important note is that none of this work would have been possible without the great documentation of the experimental details and results by G.W. Knobeloch, G. Butler, C.I. Browne, B. Erdal, B. Bayhurst, R. Prestwood, V. Armijo, J. Hasty and many others. (authors)

  12. Fission dynamics with systems of intermediate fissility

    Indian Academy of Sciences (India)

    E Vardaci; A Di Nitto; P N Nadtochy; A Brondi; G La Rana; R Moro; M Cinausero; G Prete; N Gelli; E M Kozulin; G N Knyazheva; I M Itkis

    2015-08-01

    A 4 light charged particle spectrometer, called 8 LP, is in operation at the Laboratori Nazionali di Legnaro, Italy, for studying reaction mechanisms in low-energy heavy-ion reactions. Besides about 300 telescopes to detect light charged particles, the spectrometer is also equipped with an anular PPAC system to detect evaporation residues and a two-arm time-of-flight spectrometer to detect fission fragments. The spectrometer has been used in several fission dynamics studies using as a probe light charged particles in the fission and evaporation residues (ER) channels. This paper proposes a journey within some open questions about the fission dynamics and a review of the main results concerning nuclear dissipation and fission time-scale obtained from several of these studies. In particular, the advantages of using systems of intermediate fissility will be discussed.

  13. Apatite bone cement reinforced with calcium silicate fibers.

    Science.gov (United States)

    Motisuke, Mariana; Santos, Verônica R; Bazanini, Naiana C; Bertran, Celso A

    2014-10-01

    Several research efforts have been made in the attempt to reinforce calcium phosphate cements (CPCs) with polymeric and carbon fibers. Due to their low compatibility with the cement matrix, results were not satisfactory. In this context, calcium silicate fibers (CaSiO3) may be an alternative material to overcome the main drawback of reinforced CPCs since, despite of their good mechanical properties, they may interact chemically with the CPC matrix. In this work CaSiO3 fibers, with aspect ratio of 9.6, were synthesized by a reactive molten salt synthesis and used as reinforcement in apatite cement. 5 wt.% of reinforcement addition has increased the compressive strength of the CPC by 250% (from 14.5 to 50.4 MPa) without preventing the cement to set. Ca and Si release in samples containing fibers could be explained by CaSiO3 partial hydrolysis which leads to a quick increase in Ca concentration and in silica gel precipitation. The latter may be responsible for apatite precipitation in needle like form during cement setting reaction. The material developed presents potential properties to be employed in bone repair treatment.

  14. On the development of an apatitic calcium phosphate bone cement

    Indian Academy of Sciences (India)

    Manoj Komath; H K Varma; R Sivakumar

    2000-04-01

    Development of an apatitic calcium phosphate bone cement is reported. 100 Particles of tetracalcium phosphate (TTCP) and dicalcium phosphate dihydrate (DCPD) were mixed in equimolar ratio to form the cement powder. The wetting medium used was distilled water with Na2HPO4 as accelerator to manipulate the setting time. The cement powder, on wetting with the medium, formed a workable putty. The setting times of the putty were measured using a Vicat type apparatus and the compressive strength was determined with a Universal Testing Machine. The nature of the precipitated cement was analyzed through X-ray diffraction (XRD), fourier transform infrared spectrometry (FTIR) and energy dispersive electron microprobe (EDAX). The results showed the phase to be apatitic with a calcium–to–phosphorous ratio close to that of hydroxyapatite. The microstructure analysis using scanning electron microscopy (SEM) showed hydroxyapatite nanocrystallite growth over particulate matrix surface. The structure has an apparent porosity of ∼ 52%. There were no appreciable dimensional or thermal changes during setting. The cement passed the in vitro toxicological screening (cytotoxicity and haemolysis) tests. Optimization of the cement was done by manipulating the accelerator concentration so that the setting time, hardening time and the compressive strength had clinically relevant values.

  15. beta-delayed fission from sup 2 sup 3 sup 0 Ac

    CERN Document Server

    Yang Wei Fan; Xu Yan Bing; Xong Bing; Pan Qiang Yan; He Jian Jun; Xiao Yong Hou; Li Yi

    2002-01-01

    ThO sub 2 is irradiated with 60 MeV/u sup 1 sup 8 O beams. sup 2 sup 3 sup 0 Ra is produced via the multi-nucleon transfer and dissipative fragmentation reactions of the target. sup 2 sup 3 sup 0 Ra is radio-chemical separated from ThO sub 2 and the other reaction products. The thin Ra sources are prepared. The mica fission track detectors are exposed to the Ra sources. gamma-rays of Ra decay in the sources are measured by a HPGe detector. The mica foil is etched in HF solution. The etched mica foil is scanned with an optical microscope. The fission tracks that should come from beta-delayed fission of sup 2 sup 3 sup 0 Ac are observed. The beta-delayed fission probability of sup 2 sup 3 sup 0 Ac is determined to be (1.19 +- 0.85) x 10 sup - sup 8

  16. Incorporation of iodine into apatite structure: a crystal chemistry approach using Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Jianwei eWang

    2015-06-01

    Full Text Available Materials with apatite crystal structure provide a great potential for incorporating the long-lived radioactive iodine isotope (129I in the form of iodide (I- from nuclear waste streams. Because of its durability and potentially high iodine content, the apatite waste form can reduce iodine release rate and minimize the waste volume. Crystal structure and composition of apatite was investigated for iodide incorporation into the channel of the structure using Artificial Neural Network. A total of 86 experimentally determined apatite crystal structures of different compositions were compiled from literature, and 46 of them were used to train the networks and 42 were used to test the performance of the trained networks. The results show that the performances of the networks are satisfactory for predictions of unit cell parameters a and c and channel size of the structure. The trained and tested networks were then used to predict unknown compositions of apatite that incorporates iodide. With a crystal chemistry consideration, chemical compositions that lead to matching the size of the structural channel to the size of iodide were then predicted to be able to incorporate iodide in the structural channel. The calculations suggest that combinations of A site cations of Ag+, K+, Sr2+, Pb2+, Ba2+, and Cs+, and X site cations, mostly formed tetrahedron, of Mn5+, As5+, Cr5+, V5+, Mo5+, Si4+, Ge4+, and Re7+ are possible apatite compositions that are able to incorporate iodide. The charge balance of different apatite compositions can be achieved by multiple substitutions at a single site or coupled substitutions at both A and X sites. The results give important clues for designing experiments to synthesize new apatite compositions and also provide a fundamental understanding how iodide is incorporated in the apatite structure. This understanding can provide important insights for apatite waste forms design by optimizing the chemical composition and synthesis

  17. Determination of the fission barrier height in fission of heavy radioactive beams induced by the (d,p)-transfer

    CERN Multimedia

    A theoretical framework is described, allowing to determine the fission barrier height using the observed cross sections of fission induced by the (d,p)-transfer with accuracy, which is not achievable in another type of low-energy fission of neutron-deficient nuclei, the $\\beta$-delayed fission. The primary goal is to directly determine the fission barrier height of proton-rich fissile nuclei, preferably using the radio-active beams of isotopes of odd elements, and thus confirm or exclude the low values of fission barrier heights, typically extracted using statistical calculations in the compound nucleus reactions at higher excitation energies. Calculated fission cross sections in transfer reactions of the radioactive beams show sufficient sensitivity to fission barrier height. In the probable case that fission rates will be high enough, mass asymmetry of fission fragments can be determined. Results will be relevant for nuclear astrophysics and for production of super-heavy nuclei. Transfer induced fission of...

  18. Biomimetic magnesium–carbonate-apatite nanocrystals endowed with strontium ions as anti-osteoporotic trigger

    Energy Technology Data Exchange (ETDEWEB)

    Iafisco, Michele, E-mail: michele.iafisco@istec.cnr.it; Ruffini, Andrea; Adamiano, Alessio; Sprio, Simone; Tampieri, Anna

    2014-02-01

    The present work investigates the preparation of biomimetic nanocrystalline apatites co-substituted with Mg, CO{sub 3} and Sr to be used as starting materials for the development of nanostructured bio-devices for regeneration of osteoporotic bone. Biological-like amounts of Mg and CO{sub 3} ions were inserted in the apatite structure to mimic the composition of bone apatite, whereas the addition of increasing quantities of Sr ions, from 0 up to 12 wt.%, as anti-osteoporotic agent, was evaluated. The chemical–physical features, the morphology, the degradation rates, the ion release kinetics as well as the in vitro bioactivity of the as-prepared apatites were fully evaluated. The results indicated that the incorporation of 12 wt.% of Sr can be viewed as a threshold for the structural stability of Mg–CO{sub 3}-apatite. Indeed, incorporation of lower quantity of Sr did not induce considerable variations in the chemical structure of Mg–CO{sub 3}-apatite, while when the Sr doping extent reached 12 wt.%, a dramatically destabilizing effect was detected on the crystal structure thus yielding alteration of the symmetry and distortion of the PO{sub 4}. As a consequence, this apatite exhibited the fastest degradation kinetic and the highest amount of Sr ions released when tested in physiological conditions. In this respect, the surface crystallization of new calcium phosphate phase when immersed in physiological-like solution occurred by different mechanisms and extents due to the different structural chemistry of the variously doped apatites. Nevertheless, all the apatites synthesized in this work exhibited in vitro bioactivity demonstrating their potential use to develop biomedical devices with anti-osteoporotic functionality. - Highlights: • Biomimetic nanocrystalline apatites co-substituted with Mg, CO{sub 3} and Sr were prepared. • Biological-like amounts of Mg and CO{sub 3} were inserted to mimic the composition of bone apatite. • The addition of increasing

  19. Temperature dependent fission fragment distribution in the Langevin equation

    Institute of Scientific and Technical Information of China (English)

    WANG Kun; MA Yu-Gang; ZHENG Qing-Shan; CAI Xiang-Zhou; FANG De-Qing; FU Yao; LU Guang-Cheng; TIAN Wen-Dong; WANG Hong-Wei

    2009-01-01

    The temperature dependent width of the fission fragment distributions was simulated in the Langevin equation by taking two-parameter exponential form of the fission fragment mass variance at scission point for each fission event. The result can reproduce experimental data well, and it permits to make reliable estimate for unmeasured product yields near symmetry fission.

  20. Recovery and use of fission product noble metals

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, G.A.; Rohmann, C.A.; Perrigo, L.D.

    1980-06-01

    Noble metals in fission products are of strategic value. Market prices for noble metals are rising more rapidly than recovery costs. A promising concept has been developed for recovery of noble metals from fission product waste. Although the assessment was made only for the three noble metal fission products (Rh, Pd, Ru), there are other fission products and actinides which have potential value. (DLC)

  1. Rearrangement of cluster structure during fission processes

    DEFF Research Database (Denmark)

    Lyalin, Andrey G.; Obolensky, Oleg I.; Solov'yov, Andrey V.

    2004-01-01

    Results of molecular dynamics simulations of fission reactions $Na_10^2+ -->Na_7^++ Na_3^+ and Na_18^2+--> 2Na_9^+ are presented. The dependence of the fission barriers on the isomer structure of the parent cluster is analysed. It is demonstrated that the energy necessary for removing homothetic...... groups of atoms from the parent cluster is largely independent of the isomer form of the parent cluster. The importance of rearrangement of the cluster structure during the fission process is elucidated. This rearrangement may include transition to another isomer state of the parent cluster before actual...

  2. Fission induced by nucleons at intermediate energies

    CERN Document Server

    Meo, Sergio Lo; Massimi, Cristian; Vannini, Gianni; Ventura, Alberto

    2014-01-01

    Monte Carlo calculations of fission of actinides and pre-actinides induced by protons and neutrons in the energy range from 100 MeV to 1 GeV are carried out by means of a recent version of the Li\\`ege Intranuclear Cascade Model, INCL++, coupled with two different evaporation-fission codes, GEMINI++ and ABLA07. In order to reproduce experimental fission cross sections, model parameters are usually adjusted on available (p,f) cross sections and used to predict (n,f) cross sections for the same isotopes.

  3. Fission dynamics within time-dependent Hartree-Fock: boost-induced fission

    CERN Document Server

    Goddard, P M; Rios, A

    2015-01-01

    Background: Nuclear fission is a complex large-amplitude collective decay mode in heavy nuclei. Microscopic density functional studies of fission have previously concentrated on adiabatic approaches based on constrained static calculations ignoring dynamical excitations of the fissioning nucleus, and the daughter products. Purpose: To explore the ability of dynamic mean-field methods to describe induced fission processes, using quadrupole boosts in the nuclide $^{240}$Pu as an example. Methods: Quadrupole constrained Hartree-Fock calculations are used to create a potential energy surface. An isomeric state and a state beyond the second barrier peak are excited by means of instantaneous as well as temporally extended gauge boosts with quadrupole shapes. The subsequent deexcitation is studied in a time-dependent Hartree-Fock simulation, with emphasis on fissioned final states. The corresponding fission fragment mass numbers are studied. Results: In general, the energy deposited by the quadrupole boost is quickl...

  4. Effects of fissioning nuclei distributions on fragment mass distributions for high energy fission

    Directory of Open Access Journals (Sweden)

    Rossi P C R

    2012-02-01

    Full Text Available We study the effects of fissioning nuclei mass- and energy-distributions on the formation of fragments for fission induced by high energy probes. A Monte Carlo code called CRISP was used for obtaining mass distributions and spectra of the fissioning nuclei for reactions induced by 660 MeV protons on 241Am and on 239Np, by 500 MeV protons on 208Pb, and by Bremsstrahlung photons with end-point energies at 50 MeV and 3500 MeV on 238U. The results show that even at high excitation energies, asymmetric fission may still contribute significantly to the fission cross section of actinide nuclei, while it is the dominante mode in the case of lead. However, more precise data for high energy fission on actinide are necessary in order to allow definite conclusions.

  5. Transformation of nacre coatings into apatite coatings in phosphate buffer solution at low temperature.

    Science.gov (United States)

    Guo, Yaping; Zhou, Yu

    2008-08-01

    Nacre coatings were deposited on Ti6Al4V substrates by electrophoretic technique, and subsequently converted into apatite coatings with hierarchical porous structures by treatment with a phosphate buffer solution. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma optical emission spectroscopy, X-ray photoelectron spectroscopy (XPS), and N(2) adsorption-desorption isotherms. The results show that the nacre coatings are converted into the plate-like apatite coatings via a dissolution-precipitation reaction, while the organic components of the nacre are reserved. The mesopores with pore size of 4.4 nm are formed within the plate-like structure, and the macropores are formed among the plate-like structure. Simulated body fluid (SBF) immersion tests reveal that the apatite coatings have a good in vitro bioactivity. Bone-like apatite crystals are formed on the surfaces of the apatite coatings after soaking in SBF for 12 h, and fill up the macropores on the coatings with increasing the soaking time. In addition, XPS indicates that a TiO(x) layer and PO(4) (3-) ions appear on the substrate surfaces by pretreatment with a H(3)PO(4)/HF solution. The TiO(x) layer and PO(4) (3-) ions can induce the formation of apatite crystals, resulting in a composition gradient from the oxide layer to the external apatite layer.

  6. In vitro growth of bioactive nanostructured apatites via agar-gelatin hybrid hydrogel.

    Science.gov (United States)

    Deng, Yi; Zhao, Xianghui; Zhou, Yongsheng; Zhu, Peizhi; Zhang, Li; Wei, Shicheng

    2013-12-01

    Biomimetic synthesis of bone-like carbonated apatite with good biocompatibility is a promising strategy for the development of novel biomaterials for bone engineering applications. Most research efforts have been focused on only protein-based or only polysaccharide-based template for synthesis of apatite minerals. To understand the cooperative roles of gelatin and polysaccharide playing in the biomineralization, agar hydrogel, gelatin and agar-gelatin hybrid hydrogel were respectively introduced as mineralization matrix for the in vitro growth of apatite in the study. It was shown that bundle-like carbonated apatite was successfully prepared in agar-gelatin hybrid hydrogel for the first time, through the interaction between apatite and matrix macromolecule under physiological temperature. Moreover, the in vitro biocompatibility of the prepared nanostructured apatite crystals was investigated using CCK-8 assay and alkaline phosphatase activity of osteoblast-like MC3T3-E1. Compared with HA synthesized by traditional method, the obtained apatite in agar-gelatin hybrid hydrogel could provide significantly higher cell viability and alkaline phosphatase activity. Through the study, we could better understand the role of gelatin and polysaccharide in bone formation process, and the product is a promising candidate to be used in bone tissue engineering.

  7. Biomimetic apatite-based composite materials obtained by spark plasma sintering (SPS): physicochemical and mechanical characterizations.

    Science.gov (United States)

    Brouillet, Fabien; Laurencin, Danielle; Grossin, David; Drouet, Christophe; Estournes, Claude; Chevallier, Geoffroy; Rey, Christian

    2015-08-01

    Nanocrystalline calcium phosphate apatites are biomimetic compounds analogous to bone mineral and are at the origin of the bioactivity of most biomaterials used as bone substitutes. Their unique surface reactivity originates from the presence of a hydrated layer containing labile ions (mostly divalent ones). So the setup of 3D biocompatible apatite-based bioceramics exhibiting a high reactivity requests the development of «low» temperature consolidation processes such as spark plasma sintering (SPS), in order to preserve the characteristics of the hydrated nanocrystals. However, mechanical performances may still need to be improved for such nanocrystalline apatite bioceramics, especially in view of load-bearing applications. The reinforcement by association with biopolymers represents an appealing approach, while preserving the advantageous biological properties of biomimetic apatites. Herein, we report the preparation of composites based on biomimetic apatite associated with various quantities of microcrystalline cellulose (MCC, 1-20 wt%), a natural fibrous polymer. The SPS-consolidated composites were analyzed from both physicochemical (X-ray diffraction, Fourier transform infrared, solid state NMR) and mechanical (Brazilian test) viewpoints. The preservation of the physicochemical characteristics of apatite and cellulose in the final material was observed. Mechanical properties of the composite materials were found to be directly related to the polymer/apatite ratios and a maximum crushing strength was reached for 10 wt% of MCC.

  8. Calcium Solubility In Zeolite Synthetic-Apatite Mixtures

    Science.gov (United States)

    Beiersdorfer, R.; Ming, D. W.

    1999-01-01

    Life support systems at a lunar or martian outpost will require the ability to produce food growing in 1) treated lunar or martian regolith; 2) a synthetic soil, or 3) some combination of both. Zeoponic soil, composed of NH4 (-) and K-exchanged clinoptilolite (Cp) and synthetic apatite (Ap), can provide slow-release fertilization via dissolution and ion-exchange. Equilibrium studies indicate that KNH4, P, and Mg are available to plants at sufficient levels, however, Ca is deficient. Ca availability can be increased by adding a second Ca-bearing mineral: calcite (Cal); dolomite (Dol); or wollastonite (Wol). Additions of Cal, Dol, and Wol systematically change the concentrations of Ca and P in solution. Cal has the greatest effect, Dol the least, and Wol is intermediate.

  9. Magnetic apatite for structural insights on the plasma membrane

    Science.gov (United States)

    Stanca, Sarmiza E.; Müller, Robert; Dellith, Jan; Nietzsche, Sandor; Stöckel, Stephan; Biskup, Christoph; Deckert, Volker; Krafft, Christoph; Popp, Jürgen; Fritzsche, Wolfgang

    2015-01-01

    The iron oxide-hydroxyapatite (FeOxHA) nanoparticles reported here differ from those reported before by their advantage of homogeneity and simple preparation; moreover, the presence of carboxymethyldextran (CMD), together with hydroxyapatite (HA), allows access to the cellular membrane, which makes our magnetic apatite unique. These nanoparticles combine magnetic behavior, Raman label ability and the property of interaction with the cellular membrane; they therefore represent an interesting material for structural differentiation of the cell membrane. It was observed by Raman spectroscopy, scanning electron microscopy (SEM) and fluorescence microscopy that FeOxHA adheres to the plasma membrane and does not penetrate the membrane. These insights make the nanoparticles a promising material for magnetic cell sorting, e.g. in microfluidic device applications.

  10. Magnetic apatite for structural insights on the plasma membrane.

    Science.gov (United States)

    Stanca, Sarmiza E; Müller, Robert; Dellith, Jan; Nietzsche, Sandor; Stöckel, Stephan; Biskup, Christoph; Deckert, Volker; Krafft, Christoph; Popp, Jürgen; Fritzsche, Wolfgang

    2015-01-21

    The iron oxide-hydroxyapatite (FeOxHA) nanoparticles reported here differ from those reported before by their advantage of homogeneity and simple preparation; moreover, the presence of carboxymethyldextran (CMD), together with hydroxyapatite (HA), allows access to the cellular membrane, which makes our magnetic apatite unique. These nanoparticles combine magnetic behavior, Raman label ability and the property of interaction with the cellular membrane; they therefore represent an interesting material for structural differentiation of the cell membrane. It was observed by Raman spectroscopy, scanning electron microscopy (SEM) and fluorescence microscopy that FeOxHA adheres to the plasma membrane and does not penetrate the membrane. These insights make the nanoparticles a promising material for magnetic cell sorting, e.g. in microfluidic device applications.

  11. Radionuclide Incorporation and Long Term Performance of Apatite Waste Forms

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jianwei [Louisiana State Univ., Baton Rouge, LA (United States); Lian, Jie [Rensselaer Polytechnic Inst., Troy, NY (United States); Gao, Fei [Univ. of Michigan, Ann Arbor, MI (United States)

    2016-01-04

    This project aims to combines state-of-the-art experimental and characterization techniques with atomistic simulations based on density functional theory (DFT) and molecular dynamics (MD) simulations. With an initial focus on long-lived I-129 and other radionuclides such as Cs, Sr in apatite structure, specific research objectives include the atomic scale understanding of: (1) incorporation behavior of the radionuclides and their effects on the crystal chemistry and phase stability; (2) stability and microstructure evolution of designed waste forms under coupled temperature and radiation environments; (3) incorporation and migration energetics of radionuclides and release behaviors as probed by DFT and molecular dynamics (MD) simulations; and (4) chemical durability as measured in dissolution experiments for long term performance evaluation and model validation.

  12. Biomimetic synthesis of calcium-strontium apatite hollow nanospheres

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this work,calcium-strontium apatite (Sr-HA) hollow nanospheres were synthesized by a facile biomimetic method.The structure and property of Sr-HA were characterized by FESEM,TEM,HRTEM,XRD and FT-IR spectroscopy.The influences of different ratios of calcium and strontium on the morphologies of the Sr-HA products were investigated.The experimental results revealed that the hollow spherical Sr-HA,with a size of 30-120 nm in diameter,could be synthesized when the molar ratio of Ca/Sr was 1:1.The possible formation mechanism of the hollow Sr-HA was proposed.The drug release experiments indicated that the hollow spherical Sr-HA had the property of sustained release.

  13. Nano-apatite/Polymer Biocomposite for Tissue Engineering

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A new kind of tissue engineering scaffold materials of nano-apatite ( NA ) and polyamide6( PA6) biocomposite was prepared by means of the co-solution method. The NA crystals uniformly distribute in the composite with a size of 10- 30 nm in diameter by 50- 90 nm in length. The NA/ PA6 composite has good homogeneity and high NA content, and excellent mechanical properties close to those of natural bone. The porous 3-D scaffold has not only macropores, but also micropores on the walls of macropores with porosity of about 80% and the size of pore diameter of about 300μm made by injection foam. The biocomposite can be used for bone repair and as scaffolds in tissue engineering.

  14. (d,p)-transfer induced fission of heavy radioactive beams

    CERN Document Server

    Veselsky, Martin

    2012-01-01

    (d,p)-transfer induced fission is proposed as a tool to study low energy fission of exotic heavy nuclei. Primary goal is to directly determine the fission barrier height of proton-rich fissile nuclei, preferably using the radio-active beams of isotopes of odd elements, and thus confirm or exclude the low values of fission barrier heights, typically extracted using statistical calculations in the compound nucleus reactions at higher excitation energies. Calculated fission cross sections in transfer reactions of the radioactive beams show sufficient sensitivity to fission barrier height. In the probable case that fission rates will be high enough, mass asymmetry of fission fragments can be determined. Results will be relevant for nuclear astrophysics and for production of super-heavy nuclei. Transfer induced fission offers a possibility for systematic study the low energy fission of heavy exotic nuclei at the ISOLDE.

  15. Mineralogical and geochemical studies on apatites and phosphate host rocks of Esfordi deposit, Yazd province, to determine the origin and geological setting of the apatite

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Rajabzadeh

    2014-10-01

    Full Text Available Introduction Iron-apatite ore deposits well known as Kiruna iron type formed in association with calc-alkaline volcanism from Proterozoic to Tertiary (Hitzman et al., 1992. Liquid immiscibility in an igneous system was proposed to explain the formation of the iron oxides accompanying apatite in mineralized zones (Förster and Jafarzadeh, 1994; Daliran, 1999. The mode of ore formation however, is a matter in debate. Bafq region in Central Iran is one of the greatest iron mining regions in Iran with 750 million tons of reservoir. The majority of the iron deposits contains apatite as minor mineral and underwent metamorphism-alteration in varying degrees. The mode of formation and geological setting of Esfordi iron-apatite deposit in this region with an average of 13.9 wt% apatite are discussed using geochemical and mineralogical data along with field description. Materials and methods Fifty-three samples of mineralized zones and host rocks collected from 7 cross sections were studied by conventional microscopic methods. Seven representative samples were determined by XRD at Department of Physics, Shiraz University. Fifteen and six samples were also analyzed for major and trace elements using XRF at Binaloud Co. Iran, and ICP-MS at Labwest Minerals Analysis, Australia, respectively. Microprobe analyses were carried out on apatite in Geo Forschungs Zentrum Telegrafenberg at Potsdam University, Germany. Results Field observation shows that igneous host rocks in Esfordi were intensively altered by hydrothermal fluids. The ores are surrounded by wide altered halos. Petrographic investigation indicated that the most important alterations are of potassic, carbonatitic and silicification types. Magnetite and apatite occur as major minerals, accompanied by minor hematite and goethite in the mineralized zones. Rare Earth Element (REE minerals are present as minor phases in the ores. Three apatite mineralization types (vein, massive, and disseminated were

  16. Fission fragment mass and angular distributions: Probes to study non-equilibrium fission

    Indian Academy of Sciences (India)

    R G Thomas

    2015-08-01

    Synthesis of heavy and superheavy elements is severely hindered by fission and fission-like processes. The probability of these fission-like, non-equilibrium processes strongly depends on the entrance channel parameters. This article attempts to summarize the recent experimental findings and classify the signatures of these non-equilibrium processes based on macroscopic variables. The importance of the sticking time of the dinuclear complex with respect to the equilibration times of various degrees of freedom is emphasized.

  17. Adsorption of nucleotides on biomimetic apatite: The case of adenosine 5‧ monophosphate (AMP)

    Science.gov (United States)

    Hammami, K.; Feki, H. El; Marsan, O.; Drouet, C.

    2015-10-01

    This work investigates the interaction between the nucleotide adenosine 5‧ monophosphate molecule (AMP) and a biomimetic nanocrystalline carbonated apatite as a model for bone mineral. The analogy of the apatite phase used in this work with biological apatite was first pointed out by complementary techniques. AMP adsorption isotherms were then investigated. Obtained data were fitted to a Sips isotherm with an exponent greater than one suggesting positive cooperativity among adsorbed molecules. The data were compared to a previous study relative to the adsorption of another nucleotide, cytidine monophosphate (CMP) onto a similar substrate, evidencing some effect of the chemical nature of the nucleic base. An enhanced adsorption was observed under acidic (pH 6) conditions as opposed to pH 7.4, which parallels the case of DNA adsorption on biomimetic apatite. An estimated standard Gibbs free energy associated to the adsorption process (ΔG°ads ≅ -22 kJ/mol) intermediate between "physisorption" and "chemisorption" was found. The analysis of the solids after adsorption pointed to the preservation of the main characteristics of the apatite substrate but shifts or enhancements of Raman bands attributed to AMP showed the existence of chemical interactions involving both the phosphate and adenine parts of AMP. This contribution adds to the works conducted in view of better understanding the interaction of DNA/RNA and their constitutive nucleotides and the surface of biomimetic apatites. It could prove helpful in disciplines such as bone diagenesis (DNA/apatite interface in aged bones) or nanomedicine (setup of DNA- or RNA-loaded apatite systems). Also, the adsorption of nucleic acids on minerals like apatites could have played a role in the preservation of such biomolecules in the varying conditions known to exist at the origin of life on Earth, underlining the importance of dedicated adsorption studies.

  18. Fission fragment angular distribution in heavy-ion-induced fission with anomalous behavior

    Science.gov (United States)

    Soheyli, S.; Feizi, B.

    2014-08-01

    Fission fragment angular distribution in heavy-ion-induced fission reactions is of particular importance. Transition state theory is provided to determine the angular distribution of fission fragments which includes standard saddle-point statistical and standard scission-point statistical models. The standard saddle-point statistical model was not able to reproduce the experimental fission fragment angular anisotropies for several heavy-ion-induced fission systems. In contrast to the standard saddle-point model, the standard scission-point statistical model was fairly successful in the prediction of angular anisotropy in heavy-ion-induced fission reaction systems with an anomalous behavior in angular anisotropy of fission fragments, but this model is not widely used as the standard saddle-point statistical model. In this research, a generalized model is introduced for the prediction of fission fragments angular anisotropy in the heavy-ion-induced fission reaction systems having an anomalous behavior. For this purpose, we study the N14,O16,F19+Th232;O16,F19+U238;Mg24,Si28,S32+Pb208;S32+Au197; and O16+Cm248 reaction systems. Finally, it is shown that the presented model is much more successful than previous models.

  19. Measurement of 235U Fission Yield Induced by 252Cf Fission Neutron

    Institute of Scientific and Technical Information of China (English)

    YANG; Yi; LIU; Shi-long; JIANG; Wen-gang

    2015-01-01

    We measured fission yields of 235U by 252Cf fission neutrons with the directγray spectrometric method.Square sample foils of 15 mm,abundance of 235U is 90.2%,mass of 0.7gram,covered by pure aluminum foil.After irradiations every sample was measured by HPGe spectrometry for about 2months.Based on 140Ba’s fission yield,we get relative fission yields and the results were shown in Fig.1.

  20. Structure and Phase State of Bone Apatite of Calcified Aortic Fragments with Osteoporosis

    Directory of Open Access Journals (Sweden)

    Ya.V. Khyzhnya

    2013-10-01

    Full Text Available The paper represents the results of the study on the structure and phase composition of bone apatite and fragments of calcified aorta of the same experimental animal with model osteoporosis. Examination by the X-ray and electron diffraction, electron microscopy and infrared spectroscopy reveals that pathological calcification of rabbit aorta with model osteoporosis in crystal-chemical terms is the imperfect calcium apatite Ca10(PO46(OH2. Temperature growth of ectopic apatite crystals during annealing at 900C is similar to bioapatite of bone.

  1. Energy from nuclear fission an introduction

    CERN Document Server

    De Sanctis, Enzo; Ripani, Marco

    2016-01-01

    This book provides an overview on nuclear physics and energy production from nuclear fission. It serves as a readable and reliable source of information for anyone who wants to have a well-balanced opinion about exploitation of nuclear fission in power plants. The text is divided into two parts; the first covers the basics of nuclear forces and properties of nuclei, nuclear collisions, nuclear stability, radioactivity, and provides a detailed discussion of nuclear fission and relevant topics in its application to energy production. The second part covers the basic technical aspects of nuclear fission reactors, nuclear fuel cycle and resources, safety, safeguards, and radioactive waste management. The book also contains a discussion of the biological effects of nuclear radiation and of radiation protection, and a summary of the ten most relevant nuclear accidents. The book is suitable for undergraduates in physics, nuclear engineering and other science subjects. However, the mathematics is kept at a level that...

  2. Development of fission Mo-99 production technology

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Ho; Choung, W. M.; Lee, K. I. and others

    2000-05-01

    Fission Mo-99 is the only parent nuclide of Tc-99m, an extremely useful tool for mdeical diagnosis, with an estimated usage of greater than 80% of nuclear medicine applicatons. HEU and LEU targets to optimize in HANARO irradiation condition suggested and designed for domestic production of fission Mo-99. The optimum process conditions are established in each unit process to meet quality requirements of fission Mo-99 products, and the results of performance test in combined process show Mo separation and purification yield of the above 97%. The concept of Tc generator production process is established, and the result of performance test show Tc production yield of 98.4% in Tc generator procuction process. The drafts is prepared for cooperation of technical cooperation and business investment with foreign country. Evaluation on economic feasibility is accompanied for fission Mo-99 and Tc-99m generator production.

  3. Advanced modeling of prompt fission neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Talou, Patrick [Los Alamos National Laboratory

    2009-01-01

    Theoretical and numerical studies of prompt fission neutrons are presented. The main results of the Los Alamos model often used in nuclear data evaluation work are reviewed briefly, and a preliminary assessment of uncertainties associated with the evaluated prompt fission neutron spectrum for n (0.5 MeV)+{sup 239}Pu is discussed. Advanced modeling of prompt fission neutrons is done by Monte Carlo simulations of the evaporation process of the excited primary fission fragments. The successive emissions of neutrons are followed in the statistical formalism framework, and detailed information, beyond average quantities, can be inferred. This approach is applied to the following reactions: {sup 252}Cf (sf), n{sub th} + {sup 239}Pu, n (0.5 MeV)+{sup 235}U, and {sup 236}Pu (sf). A discussion on the merits and present limitations of this approach concludes this presentation.

  4. "UCx fission targets oxidation test stand"

    CERN Document Server

    Lacroix, Rachel

    2014-01-01

    "Set up a rig dedicated to the oxidation of UCx and define a procedure for repeatable, reliable and safe method for converting UC2 fission targets into an acceptable uranium carbide oxide waste for subsequent disposal by the Swiss Authorities."

  5. New insight on the high radiation resistance of UO2 against fission fragments

    Science.gov (United States)

    Szenes, G.

    2016-12-01

    Track radii are derived for semiconductors from a temperature distribution Θ(r) in which the width of the distribution is the only materials parameter. Analysis of track data for GeS, InP, GaAs and GaN show that the projectile velocity has no effect on track radii in semiconductors. Due to the missing velocity effect, the threshold for track formation, Set = 20 keV/nm is high in semiconducting UO2 in the whole range of projectile velocities. This is the origin of the high radiation resistance for fission fragments. Consequences for the simulation experiments with insulating CeO2 are discussed. It is verified that sputtering is described accurately by the Arrhenius equation for various materials including UO2. The ion-induced surface potential has a strong effect on the activation energy.

  6. RMSRo

    DEFF Research Database (Denmark)

    Nielsen, S.B.; Clausen, O.R.; McGregor, Eoin David

    2014-01-01

    Geophysical Research Abstracts Vol. 16, EGU2014-12484, 2014 EGU General Assembly 2014 © Author(s) 2014. CC Attribution 3.0 License. RMSRo: A vitrinite reflectance model consistent with the temperature-apatite fission track system Søren B. Nielsen, Ole R. Clausen, and Eoin D. McGregor Department...... of Geoscience, Høegh-Guldbergsgade 2, 8000 Aarhus C, Denmark Observed temperature, vitrinite reflectance and apatite fission tracks provide different but related information regarding temperature history. Their combined use in borehole heat flow determination as well as thermal and tectonic reconstruction...... with the temperature-apatite fission track system. Keywords: vitrinite reflectance, basin analysis, thermal history, hydrocarbon exploration, apatite fission tracks Suggate, R.P., 1998. Relations between depth of burial, vitrinite reflectance and geothermal gradient. Jour- nal of Petroleum Geology, v. 21(1), January...

  7. A revised calculational model for fission

    Energy Technology Data Exchange (ETDEWEB)

    Atchison, F.

    1998-09-01

    A semi-empirical parametrization has been developed to calculate the fission contribution to evaporative de-excitation of nuclei with a very wide range of charge, mass and excitation-energy and also the nuclear states of the scission products. The calculational model reproduces measured values (cross-sections, mass distributions, etc.) for a wide range of fissioning systems: Nuclei from Ta to Cf, interactions involving nucleons up to medium energy and light ions. (author)

  8. Seventy-five years of nuclear fission

    Indian Academy of Sciences (India)

    S S Kapoor

    2015-08-01

    Nuclear fission process is one of the most important discoveries of the twentieth century. In these 75 years since its discovery, the nuclear fission related research has not only provided new insights in the physics of large scale motion, deformation and subsequent division of a heavy nucleus, but has also opened several new frontiers of research in nuclear physics. This article is a narrative giving an overview of the landmarks of the progress in the field.

  9. Detector instrumentation for nuclear fission studies

    Indian Academy of Sciences (India)

    Akhil Jhingan

    2015-09-01

    The study of heavy-ion-induced fusion–fission reactions require nuclear instrumentation that include particle detectors such as proportional counters, ionization chambers, silicon detectors, scintillation detectors, etc., and the front-end electronics for these detectors. Using the detectors mentioned above, experimental facilities have been developed for carrying out fusion–fission experiments. This paper reviews the development of detector instrumentation at IUAC.

  10. MCNP6 Fission Multiplicity with FMULT Card

    Energy Technology Data Exchange (ETDEWEB)

    Wilcox, Trevor [Los Alamos National Laboratory; Fensin, Michael Lorne [Los Alamos National Laboratory; Hendricks, John S. [Los Alamos National Laboratory; James, Michael R. [Los Alamos National Laboratory; McKinney, Gregg W. [Los Alamos National Laboratory

    2012-06-18

    With the merger of MCNPX and MCNP5 into MCNP6, MCNP6 now provides all the capabilities of both codes allowing the user to access all the fission multiplicity data sets. Detailed in this paper is: (1) the new FMULT card capabilities for accessing these different data sets; (2) benchmark calculations, as compared to experiment, detailing the results of selecting these separate data sets for thermal neutron induced fission on U-235.

  11. Modeling Fission Product Sorption in Graphite Structures

    Energy Technology Data Exchange (ETDEWEB)

    Szlufarska, Izabela [University of Wisconsin, Madison, WI (United States); Morgan, Dane [University of Wisconsin, Madison, WI (United States); Allen, Todd [University of Wisconsin, Madison, WI (United States)

    2013-04-08

    The goal of this project is to determine changes in adsorption and desorption of fission products to/from nuclear-grade graphite in response to a changing chemical environment. First, the project team will employ principle calculations and thermodynamic analysis to predict stability of fission products on graphite in the presence of structural defects commonly observed in very high- temperature reactor (VHTR) graphites. Desorption rates will be determined as a function of partial pressure of oxygen and iodine, relative humidity, and temperature. They will then carry out experimental characterization to determine the statistical distribution of structural features. This structural information will yield distributions of binding sites to be used as an input for a sorption model. Sorption isotherms calculated under this project will contribute to understanding of the physical bases of the source terms that are used in higher-level codes that model fission product transport and retention in graphite. The project will include the following tasks: Perform structural characterization of the VHTR graphite to determine crystallographic phases, defect structures and their distribution, volume fraction of coke, and amount of sp2 versus sp3 bonding. This information will be used as guidance for ab initio modeling and as input for sorptivity models; Perform ab initio calculations of binding energies to determine stability of fission products on the different sorption sites present in nuclear graphite microstructures. The project will use density functional theory (DFT) methods to calculate binding energies in vacuum and in oxidizing environments. The team will also calculate stability of iodine complexes with fission products on graphite sorption sites; Model graphite sorption isotherms to quantify concentration of fission products in graphite. The binding energies will be combined with a Langmuir isotherm statistical model to predict the sorbed concentration of fission

  12. Spontaneous fission of the heaviest elements

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, D.C.

    1989-04-01

    Although spontaneous fission was discovered in /sup 238/U in 1940, detailed studies of the process were first made possible in the 1960's with the availability of milligram quantities of /sup 252/Cf. The advent of solid-state detectors made it possible to perform measurements of coincident fission fragments from even very short-lived spontaneous fission activities or those available in only very small quantities. Until 1971 it was believed that the main features of the mass and kinetic-energy distributions were essentially the same as those for thermal neutron-induced fission and that all low-energy fission proceeded via asymmetric mass division with total kinetic energies which could be derived by linear extrapolation from those of lighter elements. In 1971, measurements of /sup 257/Fm showed an increase in symmetric mass division with anomalously high TKE's. Subsequent experiments showed that in /sup 258/Fm and /sup 259/Fm, the most probable mass split was symmetric with very high total kinetic energy. Measurements for the heavier elements have shown symmetric mass distributions with both high and low total kinetic energies. Recent results for spontaneous fission properties of the heaviest elements are reviewed and compared with theory. 31 refs., 8 figs., 1 tab.

  13. Characterization by infrared spectrometry of chlorine and fluorine ions in apatites. Detection des ions chlore et fluor dans les apatites par spectrometrie infrarouge

    Energy Technology Data Exchange (ETDEWEB)

    Baumer, A. (Nice Univ., 06 (France)); Guilhot, B.; Gibert, R.; Vernay, A.M. (Ecole Nationale Superieure des Mines, 42 - Saint-Etienne (France)); Ohnenstetter, D. (Centre National de la Recherche Scientifique (CNRS), 45 - Orleans-la-Source (France))

    1994-07-01

    Synthetic hydroxyapatites with low chlorine and fluorine contents have been prepared hydrothermally according to the reaction: Ca[sub 5] (PO[sub 4])[sub 3] OH + xNH[sub 4]Cl or + xNH[sub 4]F. The infrared spectra of these samples show that the 3,498 cm[sup -1] band of OH, CI apatites and 3,545 cm[sup -1] band of OH, F apatites make it possible to detect respectively 350 ppm of chlorine and 150 ppm of fluorine. A comparative infrared study of natural apatites confirms that the 3,485 and 3,480 cm[sup -1] bands must be attributed to the O-H...CI hydrogen bond. (authors). 3 tabs., 2 figs., 16 refs.

  14. Improvement of RVNRL film properties by adding fumed silica and hydroxy apatite

    Directory of Open Access Journals (Sweden)

    Adul Thiangchanya

    2003-01-01

    Full Text Available The effect of adding fumed silica and hydroxy apatite to Radiation Vulcanized Natural Rubber Latex (RVNRL for improving tear strength, aging properties, degradability and water-soluble protein content of rubber films has been investigated. The addition of fumed silica and hydroxy apatite in RVNRL improves tear strength and aging properties of rubber films, whereas tensile strength and degradability of rubber films were unchanged during storage at room temperature. The water-soluble protein content in rubber films was reduced by immobilization of the fumed silica and hydroxy apatite and enhanced by addition of ZnO. This may reduce allergy problems of natural rubber latex products caused by water-soluble protein. The MST of the RVNRL with fumed silica and hydroxy apatite indicated that the latex must be used within two months after mixing because of its stability.

  15. Preparation of low-crystalline apatite nanoparticles and their coating onto quartz substrates.

    Science.gov (United States)

    Kawashita, Masakazu; Taninai, Koji; Li, Zhixia; Ishikawa, Kunio; Yoshida, Yasuhiro

    2012-06-01

    We prepared low-crystalline apatite nanoparticles and coated them onto a surface of a Au/Cr-plated quartz substrate by the electrophoretic deposition (EPD) method or by using a self-assembled monolayer of 11-mercaptoundecanoic acid (SAM method). Low-crystalline apatite nanoparticles around 10 nm in size with extremely low contents of undesirable residual products were obtained by adding (NH(4))(2)HPO(4) aqueous droplets into a modified synthetic body fluid solution that contained Ca(CH(3)COO)(2). The apatite nanoparticles were successfully coated by either the EPD method or the SAM method; the nanoparticle coating achieved by the SAM method was more uniform than that achieved by the EPD method. The present SAM method is expected to be a promising technique for obtaining a quartz substrate coated with apatite nanoparticles, which can be used as a quartz crystal microbalance device.

  16. Bioceramics of apatites: an option for bone regeneration; Bioceramica de apatitas: uma opcao para regeneracao ossea

    Energy Technology Data Exchange (ETDEWEB)

    Arxer, Eliana Alves; Almeida Filho, Edson de; Guastaldi, Antonio Carlos, E-mail: iarxer@iq.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Araraquara, SP (Brazil). Instituto de Quimica

    2011-07-01

    The bioceramics of calcium phosphate called apatite, are widely used as material for bone replacement and regeneration, due to its similarity to the mineral component of bones and teeth. The apatites are biocompatible, bioactive and integrate with living tissue by the same active process of physiological bone remodeling. These bioceramics may be used in medical, dental and orthopedic applications. In this research, it was used the wet method for the synthesis of the powder and biomimetic method for coating the surface. The Solubility study was performed in the layer deposited, apatite, for possible application as a platform for inorganic drug delivery. The bioceramics were characterized by MEV, DRX, and EDS. The curves of solubility of apatite in coatings showed that the OCP phase had a higher rate of release in the short term (4 days) while the HA phase showed a gradual release throughout the experiment (16 days). (author)

  17. REE Geochemical Characteristics of Apatite,Sphene and Zircon from Alkaline Rocks

    Institute of Scientific and Technical Information of China (English)

    周玲棣; 王杨传

    1989-01-01

    The accessory minerals apatite and sphene are the main carriers of REE in alkaline rocks.Their chondrite-normalized REE patterns decline sharply to the right as those of the host rocks,In the patterns an obvious negative Eu anomaly and a positive Ce anomaly can be seen in apatite and sphene,respectively.Zircon from alkaline rocks is different in REE pattern,I,e,. a nearly symmetric"V"-shaped pattern with a maximum negative Eu anomaly.Compared with the equivalents from granites,apatite,sphene and zircon from alkaline rocks are all characterized by higher (La/Yb)N ratio and less Eu depletion,As to the relative contents of REE in minerals,apatite,sphene and zircon are enriched in LREE,MREE and HREE respectively,depending on their crystallochemical properties.

  18. Preparation of Laminin-apatite-polymer Composites Using Metastable Calcium Phosphate Solutions

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A synthetic polymer with a laminin-apatite composite layer on its surface would be useful as a percutaneous device. The preparation of such a composite was attempted in the present study using poly ( ethylene terephthalate ) (PET) and polyethylene ( PE ) as the synthetic polymer. PET and PE plates and those pretreated with an oxygen plasma were alternately dipped in calcium and phosphate ion solutions, and then immersed in a metastable ealcium phosphate solution supplemented with laminin ( LCP solution ). The PET and PE plates pretreated with an oxygen plasma formed a uniform and continuous layer of a laminin- apatite composite on their surfaces. In contrast, the PET and PE plates that had not been pretreated with an oxygen plasma did not form a continuous layer of a laminin-apatite composite on their surfaces. The hydrophilic functional groups on the PET and PE surfaces introduced by the plasma treatment were responsible for the successful laminin-apatite composite coating.

  19. U-Th-Pb Systematics in Zircon and Apatite from the Chicxulub Crater, Mexico

    Science.gov (United States)

    Kring, D. A.; Shaulis, B. J.; Schmieder, M.; Lapen, T. J.

    2016-08-01

    We probe the U-Th-Pb systematics in zircon and apatite to determine if post-impact hydrothermal activity produced discernible effects that are related to the duration, thermal evolution, and chemistry of the hydrothermal system.

  20. Geochemistry and genesis of apatite bearing Fe oxide Dizdaj deposit, SE Zanjan

    Directory of Open Access Journals (Sweden)

    Ghasem Nabatian

    2009-09-01

    Full Text Available Sorkheh-Dizaj apatite-iron oxide deposit is located 32 km southeast of Zanjan. The area is situated within the Tarom subzone of Western Alborz-Azarbaijan structural zone. The oldest units at the Sorkheh-Dizaj area are Eocene trachyte, trachyandesite, olivine basalt and volcanoclastic brecciate tuff and lapilli tuff which intruded by a quartz-monzonite, monzonite and granite subvolcanic pluton of Upper Eocene- Early Oligocene age. Subvolcanic plutonic rocks in the area show characteristics of the I-type granites. Magmatism of the area is of synorogenic to postorogenic related to magmatic arc environments. Mineralization at the area is divided into three main zones (A, B and C that all of which are located in the host subvolcanic pluton. These three zones are similar in terms of host rock, mineralogy, alteration, structure, texture and metal content. Mineralization in the volcanic rocks occurs as veins similar to those in three main zones, but less abundant. Geometry of the ore bodies is of vein type and their textures are stockwork, massive, banded, brecciate and vein-veinlet. The most important minerals at Sorkheh-Dizaj deposit are magnetite (low Ti and apatite that associated with them minor sulfide minerals such as chalcopyrite, bornite and pyrite. Minerals such as ilmenite, spinel (titanium magnetite, galena and sphalerite occur in low contents. The supergene minerals like chalcocite, malachite, azurite, covellite, hematite and goethite have been formed due to weathering and supergene processes. The main alterations at the deposit are K-feldspar metasomatism, actinolitization, argillic, sericitization, silicification, tourmalinization, and chlorite-epidotic. Rare earth elements (REE studies demonstrate that the deposit is more enriched in LREE than in HREE. The REE patterns in the apatite, magnetite and host rocks are similar suggesting a magmatic relationship. The REE contents of the apatites are higher than those of the host rocks and

  1. Fluoride enhances transfection activity of carbonate apatite by increasing cytoplasmic stability of plasmid DNA

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, E.H., E-mail: md.ezharul.hoque@med.monash.edu.my [Jeffrey Cheah School of Medicine and Health Sciences, Monash University Sunway Campus, Jalan Lagoon Selatan, Bandar Sunway, Selangor Darul Ehsan (Malaysia)

    2011-06-17

    Highlights: {yields} Cytoplasmic stability of plasmid DNA is enhanced by fluoride incorporation into carbonate apatite carrier. {yields} Fluoridated carbonate apatite promotes a robust increase in transgene expression. {yields} Controlled dissolution of fluoridated carbonate apatite in endosomal acidic environment might buffer the endosomes and prevent degradation of the released DNA. -- Abstract: Intracellular delivery of a functional gene or a nucleic acid sequence to specifically knockdown a harmful gene is a potential approach to precisely treat a critical human disease. The intensive efforts in the last few decades led to the development of a number of viral and non-viral synthetic vectors. However, an ideal delivery tool in terms of the safety and efficacy has yet to be established. Recently, we have developed pH-sensing inorganic nanocrystals of carbonate apatite for efficient and cell-targeted delivery of gene and gene-silencing RNA. Here we show that addition of very low level of fluoride to the particle-forming medium facilitates a robust increase in transgene expression following post-incubation of the particles with HeLa cells. Confocal microscopic observation and Southern blotting prove the cytoplasmic existence of plasmid DNA delivered by likely formed fluoridated carbonate apatite particles while degradation of plasmid DNA presumably by cytoplasmic nucleases was noticed following delivery with apatite particles alone. The beneficial role of fluoride in enhancing carbonate apatite-mediated gene expression might be due to the buffering potential of generated fluoridated apatite in endosomal acidic environment, thereby increasing the half-life of delivered plasmid DNA.

  2. Remediation of copper contaminated soil by using different particle sizes of apatite: a field experiment.

    Science.gov (United States)

    Xing, Jinfeng; Hu, Tiantian; Cang, Long; Zhou, Dongmei

    2016-01-01

    The particle size of apatite is one of the critical factors that influence the adsorption of heavy metals on apatite in the remediation of heavy metal contaminated soils using apatite. However, little research has been done evaluating the impact of different particle sizes of apatite on immobilization remediation of heavy metal polluted soils in field. In this study, the adsorption isothermal experiments of copper on three kinds of apatite was tested, and the field experiment by using different particle sizes apatite [nano-hydroxyapatite (NAP), micro-hydroxyapatite (MAP), ordinary particle apatite (OAP)] at a same dosage of 25.8 t/ha (1.16 %, W/W) was also conducted. Ryegrass was chosen as the test plant. The ryegrass biomass, the copper contents in ryegrass and the copper fractionations in soil were determined after field experiments. Results of adsorption experiments showed that the adsorption amounts of copper on OAP was the lowest among different particles. The adsorption amounts of copper on MAP was higher than NAP at high copper equilibrium concentration (>1 mmol L(-1)), an opposite trend was obtained at low copper concentration (soil pH, decrease the available copper concentration in soil, provide more nutrient phosphate and promote the growth of ryegrass. The ryegrass biomass and the copper accumulation in ryegrass were the highest in MAP among all treatments. The effective order of apatite in phytoremediation of copper contaminated field soil was MAP > NAP > OAP, which was attributed to the high adsorption capacity of copper and the strong releasing of phosphate by MAP.

  3. Influence of Microstructure and Sintering Routes on Transport Properties of Apatite Materials for Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    A.Chesnaud; C.Estournes; G.Dezannau

    2007-01-01

    1 Results Oxy-apatite materials are thought as zirconia-substitutes in Solid Oxide Fuel Cells due to their fast ionic conduction. However, the well known difficulties related to their densification prevent them from being used as such. This study presents strategies to obtain oxy-apatite dense materials and the influence of elaboration route on transport properties. Particular emphasis is put on the microstructure effect on ion conduction. By the combined use of freeze-drying and conventional or spark p...

  4. Dual-fission chamber and neutron beam characterization for fission product yield measurements using monoenergetic neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Bhatia, C.; Fallin, B. [Department of Physics, Duke University, Durham, NC 27708 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Gooden, M.E., E-mail: megooden@tunl.duke.edu [Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Department of Physics, North Carolina State University, Raleigh, NC 27605 (United States); Howell, C.R. [Department of Physics, Duke University, Durham, NC 27708 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Kelley, J.H. [Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Department of Physics, North Carolina State University, Raleigh, NC 27605 (United States); Tornow, W. [Department of Physics, Duke University, Durham, NC 27708 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Arnold, C.W.; Bond, E.M.; Bredeweg, T.A.; Fowler, M.M.; Moody, W.A.; Rundberg, R.S.; Rusev, G.; Vieira, D.J.; Wilhelmy, J.B. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Becker, J.A.; Macri, R.; Ryan, C.; Sheets, S.A.; Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); and others

    2014-09-01

    A program has been initiated to measure the energy dependence of selected high-yield fission products used in the analysis of nuclear test data. We present out initial work of neutron activation using a dual-fission chamber with quasi-monoenergetic neutrons and gamma-counting method. Quasi-monoenergetic neutrons of energies from 0.5 to 15 MeV using the TUNL 10 MV FM tandem to provide high-precision and self-consistent measurements of fission product yields (FPY). The final FPY results will be coupled with theoretical analysis to provide a more fundamental understanding of the fission process. To accomplish this goal, we have developed and tested a set of dual-fission ionization chambers to provide an accurate determination of the number of fissions occurring in a thick target located in the middle plane of the chamber assembly. Details of the fission chamber and its performance are presented along with neutron beam production and characterization. Also presented are studies on the background issues associated with room-return and off-energy neutron production. We show that the off-energy neutron contribution can be significant, but correctable, while room-return neutron background levels contribute less than <1% to the fission signal.

  5. Inclusive spectra of hadrons created by color tube fission; 1, Probability of tube fission

    CERN Document Server

    Gedalin, E V

    1997-01-01

    The probability of color tube fission that includes the tube surface small oscillation corrections is obtained with pre-exponential factor accuracy on the basis of previously constructed color tube model. Using these expressions the probability of the tube fission in $n$ point is obtained that is the basis for calculation of inclusive spectra of produced hadrons.

  6. Protein content of human apatite and brushite kidney stones: significant correlation with morphologic measures.

    Science.gov (United States)

    Pramanik, Rocky; Asplin, John R; Jackson, Molly E; Williams, James C

    2008-10-01

    Apatite and brushite kidney stones share calcium and phosphate as their main inorganic components. We tested the hypothesis that these stone types differ in the amount of proteins present in the stones. Intact stones were intensively analyzed by microcomputed tomography (micro CT) for both morphology (including the volume of voids, i.e., space devoid of X-ray dense material) and mineral type. To extract all proteins present in kidney stones in soluble form we developed a three-step extraction procedure using the ground stone powder. Apatite stones had significantly higher levels of total protein content and void volume compared to brushite stones. The void volume was highly correlated with the total protein contents in all stones (r2 = 0.61, P brushite stones contained significantly fewer void regions and proteins than did apatite stones (3.2 +/- 4.5% voids for brushite vs. 10.8 +/- 11.2% for apatite, P brushite vs. 6.0 +/- 2.4% for apatite, P brushite and apatite stones is higher than that was previously thought, and also suggest that micro CT-visible void regions are related to the presence of protein.

  7. Apatite deposition on titanium surfaces--the role of albumin adsorption.

    Science.gov (United States)

    Serro, A P; Fernandes, A C; Saramago, B; Lima, J; Barbosa, M A

    1997-07-01

    Titanium implant surfaces are known to spontaneously nucleate apatite layers when in contact with simulated body fluids. However, adsorption of proteins may influence the process of apatite layer formation. In this study the role of bovine serum albumin (BSA) adsorption in the process of apatite deposition on titanium substrates is investigated. Deposition of calcium phosphate was induced by immersing titanium substrates in a Hank's balanced salt solution (HBSS) for times ranging from 1 to 23 days. The resulting substrates were studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), wettability measurements and electrochemical impedance determinations. All these methods indicate the presence of a calcium phosphate layer. The same procedure was repeated substituting HBSS with a solution of BSA in HBSS. Although SEM, EDS and electrochemical impedance spectra do not reveal the presence of an apatite layer, XPS analysis strongly indicates that the inhibition of apatite formation by BSA is only partial. The competition between BSA adsorption and apatite deposition seems to lead to a mixed film where the protein co-exists with calcium phosphate. Wettability studies suggest that this surface film is heterogeneous and porous, similar to the thicker films formed in albumin-free HBSS.

  8. Diagenetic uptake of rare earth elements by conodont apatite

    Science.gov (United States)

    Zhang, L.; Algeo, T. J.; Cao, L.; Zhao, L.; Chen, Z. Q.; Li, Z.

    2015-12-01

    The rare earth element (REE) composition of bioapatite has long been used as a proxy for ancient seawater chemistry and paleomarine environmental reconstruction, based on the assumption of preservation of a hydrogenous (seawater-derived) REE signal. Recent work, however, has begun to question the provenance of REEs in conodonts, emphasizing the importance of REEs released by the lithogenous fraction of the sediment and subsequently adsorbed onto conodont apatite in the burial environment. Here, we investigate patterns of REE and trace-element abundance in conodonts and their host sediments from the Early to Late Ordovician Huanghuachang and Chenjiahe sections of Hubei Province, South China. Several lines of evidence indicate that REEs in the conodont samples were acquired mainly from clay minerals in the host sediment during burial diagenesis: (1) REEs in conodonts show a strong positive correlation to Th and other lithogenic elements; (2) conodonts and whole-rock samples show general patterns of REE and trace-element enrichment that are highly similar to each other and bear no resemblance to seawater elemental concentrations; (3) similar patterns are observed in Triassic conodonts and whole-rock samples; and (4) Y/Ho ratios in conodonts are mostly 90% of REEs from lithogenous sources. Conodonts show pronounced middle rare earth element (MREE) enrichment, a pattern that is unambiguously of diagenetic origin owing to its association with lower Y/Ho ratios. With increasing MREE enrichment of conodont samples, U concentrations and LaN/YbN ratios shift from high to low, and Mn concentrations from low to high. These patterns suggest that conodont diagenesis was initiated at shallow burial depths under suboxic conditions (i.e., in the zone of Mn(IV) and Fe(III) reduction) but continued at greater burial depths, with most acquisition of secondary REEs at later diagenetic stages. Our findings indicate that (1) conodont apatite frequently does not preserve a recognizable

  9. Cosmogenic and nucleogenic 3He in apatite, titanite, and zircon

    Science.gov (United States)

    Farley, K. A.; Libarkin, J.; Mukhopadhyay, S.; Amidon, W.

    2006-08-01

    Cosmogenic 3He was measured in apatite, titanite, and zircon and cosmogenic 21Ne in quartz at 13 depth intervals in a 2.7-m long drill core in a Miocene ignimbrite from the Altiplano of Bolivia. All three 3He depth profiles as well as the 21Ne profile attenuate exponentially with depth, indicating that both of these isotopes are cosmogenic in origin with no significant contribution from other sources. The attenuation lengthscale for 3He production of Λ = 180 ± 11 g/cm 2 is consistent with expectations for neutron spallation, and is identical to that found for the cosmogenic 21Ne in quartz. By normalizing the measured 3He concentrations to 21Ne and using the independently known cosmogenic 21Ne production rate, the apparent cosmogenic 3He production rates in apatite, titanite, and zircon were respectively found to be 112, 97, and 87 atoms/g/yr at sea-level and high latitude. The formal uncertainty on these estimates is ˜ 20% (2 σ), and arises in equal parts from uncertainties in the measured 3He/ 21Ne ratios and the uncertainty in the 21Ne production rate. However an additional factor affecting the apparent 3He production rate in these phases arises from the long stopping range of spalled 3He and tritium (which decays to 3He). Because all three accessory phases have higher mean atomic number than major rock-forming minerals, they will have lower 3He production rates than their surroundings. As a consequence the long stopping ranges will cause a net implantation of 3He and therefore higher apparent production rates than would apply for purely in-situ production. Thus these apparent production rates apply only to the specific grain sizes analyzed. Analysis of sieved zircon aliquots suggests that a factor of 2 increase in grain size (from ˜ 50 to ˜ 100 μm cross-section) yields a 10% decrease in apparent production rate. While this effect warrants further study, the grain sizes analyzed here are typical of the accessory phases commonly encountered, so the apparent

  10. Isotopic fission fragment distributions as a deep probe to fusion-fission dynamics

    CERN Document Server

    Farget, F; Delaune, O; Tarasov, O B; Derkx, X; Schmidt, K -H; Amthor, A M; Audouin, L; Bacri, C -O; Barreau, G; Bastin, B; Bazin, D; Blank, B; Benlliure, J; Caceres, L; Casarejos, E; Chibihi, A; Fernandez-Dominguez, B; Gaudefroy, L; Golabek, C; Grevy, S; Jurado, B; Kamalou, O; Lemasson, A; Lukyanov, S; Mittig, W; Morrissey, D J; Navin, A; Pereira, J; Perrot, L; Rejmund, M; Roger, T; Saint-Laurent, M -G; Savajols, H; Schmitt, C; Sherill, B M; Stodel, C; Taieb, J; Thomas, J -C; Villari, A C

    2012-01-01

    During the fission process, the nucleus deforms and elongates up to the two fragments inception and their final separation at scission deformation. The evolution of the nucleus energy with deformation is determined by the macroscopic properties of the nucleus, and is also strongly influenced by the single-particle structure of the nucleus. The fission fragment distribution is a direct consequence of the deformation path the nucleus has encountered, and therefore is the most genuine experimental observation of the potential energy landscape of the deforming nucleus. Very asymmetric fusion-fission reactions at energy close to the Coulomb barrier, produce well-defined conditions of the compound nucleus formation, where processes such as quasi-fission, pre-equilibrium emission and incomplete fusion are negligible. In the same time, the excitation energy is sufficient to reduce significantly structural effects, and mostly the macroscopic part of the potential is responsible for the formation of the fission fragmen...

  11. Genesis of iron-apatite ores in Posht-e-Badam Block (central Iran) using REE geochemistry

    Indian Academy of Sciences (India)

    Mir Ali Asghar Mokhtari; Ghader Hossein Zadeh; Mohamad Hashem Emami

    2013-06-01

    Rare earth elements in apatites of different ore types show characteristic patterns which are related to different modes of formation of the ores. Most of the apatite-bearing iron ores are associated with alkaline magmas with LREE/HREE fractionation varying from moderate to steep. Iron-apatite deposits in Posht-e-Badam Block (Central Iran) have a high concentration of REE (more than 1000 ppm up to 2.5%), and show a strong LREE/HREE ratio with a pronounced negative Eu anomaly. This REE pattern is typical of magmatic apatite and quiet distinct from sedimentary apatites (phosphorites) which have a low REE contents and Ce negative anomalies. On the other hand, they are comparable to the REE patterns of apatites in Kiruna-type iron ores in different parts of the world. The REE patterns of apatites, iron-apatite ores and iron ores are similar and only have different REE contents. This similarity indicates a genetic relation for these rocks. Most of the iron-apatite deposits in Central Iran have similar REE patterns too, which in turn show a genetic relation for all of these deposits. This similarity indicates a similar origin and processes in their genesis. There are some small intrusions around some of the iron-apatite deposits that are petrographically identified as syenite and gabbro. These intrusions also have REE patterns similar to that of iron-apatite ores. This demonstrates a genetic relation between these intrusions and iron-apatite ores. The REE patterns of apatites in different deposits of Posht-e-Badam Block iron-apatite ores show an affinity to alkaline to sub-alkaline magmas and rifting environment. The alkaline host rocks of Central Iran iron-apatite ores are clearly related to an extensional setting where rifting was important (SSE–NNW fault lines). A probable source for this large scale ore forming processes is relatively low partial melting of mantle rocks. The ores have originated by magmatic differentiation as a late phase in the volcanic cycle

  12. Lanthanum germanate-based apatites as electrolyte for SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Marrero-Lopez, D.; Diaz-Carrasco, P.; Ramos-Barrado, J.R. [Departamento de Fisica Aplicada I, Laboratorio de Materiales y Superficies (Unidad Asociada al C.S.I.C.), Universidad de Malaga, 29071 Malaga (Spain); Pena-Martinez, J. [Instituto de Energias Renovables, Parque Tecnologico, Universidad de Castilla La Mancha, 02006 Albacete (Spain); Ruiz-Morales, J.C. [Departamento de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain)

    2011-02-15

    Germanate apatites with composition La{sub 10-x}Ge{sub 5.5}Al{sub 0.5}O{sub 26.75-3x/2} have been evaluated for the first time as possible electrolytes for solid oxide fuel cells (SOFCs). Different electrode materials have been considered in this study, i.e. manganite, ferrite, nickelates and cobaltite as cathode materials; and NiO-CGO composite and chromium-manganite as anodes. The chemical compatibility and electrochemical performance of these electrodes with La{sub 9.8}Ge{sub 5.5}Al{sub 0.5}O{sub 26.45} have been studied by X-ray powder diffraction (XRPD) and impedance spectroscopy. The XRPD analysis did not reveal appreciable bulk reactivity with the formation of reaction products between the germanate electrolyte and these electrodes up to 1,200 C. However, a significant cation interdiffusion was observed by energy dispersive spectroscopy (EDS) at the electrode/electrolyte interface, which leads to a significant decrease of the performance of these electrodes. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Electrical properties of iron doped apatite-type lanthanum silicates

    Institute of Scientific and Technical Information of China (English)

    SHI Qingle; ZHANG Hua

    2012-01-01

    The effect of Fe doping on the electrical properties of lanthanum silicates was investigated.The apatite-type lanthanum silicates La10Si6-xFexO27-x/2 (x=0.2,0.4,0.6,0.8,1.0) were synthesized via sol-gel process.The unit cell volume increased with Fe doping because the ionic radius of Fe3+ ion is larger than that of Si4+ ion.The conductivities of La10Si6-xFexO27 x/2 first increased and then decreased with the increasing of Fe content.The increase of the conductivity might be attributed to the distortion of the cell lattice,which assisted the migration of the interstitial oxygen ions.The decrease of the conductivity might be caused by the lower concentration of interstitial oxygen ions.The optimum Fe doping content in lanthanum silicates was 0.6.La10Si5.4Fe0.6O26.7 exhibited the highest ionic conductivity of 2.712× 10-2 S/cm at 800 ℃.The dependence of conductivity on oxygen partial pressure p(O2) suggested that the conductivity of La10Si6-xFexO27-x/2 was mainly contributed by ionic conductivity.

  14. Constant composition kinetics study of carbonated apatite dissolution

    Science.gov (United States)

    Tang, Ruikang; Henneman, Zachary J.; Nancollas, George H.

    2003-03-01

    The carbonated apatites (CAP) may be more suitable models for biominerals such as bone and dental hard tissues than is pure hydroxyapatite (HAP) since they have similar chemical compositions. Although they contain only a relatively small amount of carbonate, the solubility and dissolution properties are different. The solubility product of the CAP particles used in this dissolution study, 2.88×10 -112 mol 18 l -18, was significantly greater than that of HAP, 5.52×10 -118 mol 18 l -18. The kinetics of dissolution of CAP has been studied using the constant composition (CC) method. At low undersaturations, the dissolution reaction appeared to be controlled mainly by surface diffusion with an effective reaction order of 1.9±0.1 with respect to the relative undersaturation. These results together with those obtained by scanning electron microscopy (SEM) suggest a dissolution model. Based on the surface diffusion theory of Burton, Cabrera and Frank (BCF). The interfacial tension between CAP and the aqueous phase calculated from this dissolution model, 9.0 m J m -2, was consistent with its relatively low solubility. An abnormal but interesting dissolution behavior is that the CAP dissolution rate was relatively insensitive to changes in calcium and phosphate concentrations at higher undersaturations, suggesting the importance of the carbonate component under these conditions.

  15. New ytterbium-doped apatite crystals for flexible laser design

    Energy Technology Data Exchange (ETDEWEB)

    Payne, S.A.; DeLoach, L.D.; Smith, L.K.; Krupke, W.F. [Lawrence Livermore National Lab., CA (United States); Chai, B.H.T.; Loutts, G. [Univ. of Central Florida, Orlando, FL (United States). Center for Research and Education in Optics and Lasers

    1994-03-01

    A new class of Yb-lasers is summarized in this article. The apatite family of crystals has been found to impose favorable spectroscopic and laser properties on the Yb{sup 3+} activator ion. Crystals of Yb-doped Ca{sub 5}(PO{sub 4}){sub 3}F, Sr{sub 5}(PO{sub 4}){sub 3}F, Ca{sub x}Sr{sub 5{minus}x}(PO{sub 4}){sub 3}F, and Sr{sub 5}(VO{sub 4}){sub 3}F have been grown and investigated. Several useful laser crystals have been identified which offer a variety of fundamental laser parameters for designing diode-pumped systems. In general, this class of materials is characterized by high emission cross sections (3.6--13.1 {times} 10{sup {minus}20} cm{sup 2}), useful emission lifetimes (0.59--1.26 msec), a strong pump band ({sigma}{sub abs} = 2.0--10.0 {times} 10{sup {minus}20} cm{sup 2}) and pump and extraction wavelengths near 900 and 1,045 nm, respectively. Efficient lasing has been demonstrated for several of the members of this class of materials, and high optical quality crystals have been grown by the Czochralski method.

  16. Anatomy of neck configuration in fission decay

    CERN Document Server

    Patra, S K; Satpathy, L

    2010-01-01

    The anatomy of neck configuration in the fission decay of Uranium and Thorium isotopes is investigated in a microscopic study using Relativistic mean field theory. The study includes $^{236}U$ and $^{232}Th$ in the valley of stability and exotic neutron rich isotopes $^{250}U$, $^{256}U$, $^{260}U$, $^{240}Th$, $^{250}Th$, $^{256}Th$ likely to play important role in the r-process nucleosynthesis in stellar evolution. Following the static fission path, the neck configurations are generated and their composition in terms of the number of neutrons and protons are obtained showing the progressive rise in the neutron component with the increase of mass number. Strong correlation between the neutron multiplicity in the fission decay and the number of neutrons in the neck is seen. The maximum neutron-proton ratio is about 5 for $^{260}$U and $^{256}$Th suggestive of the break down of liquid-drop picture and inhibition of the fission decay in still heavier isotopes. Neck as precursor of a new mode of fission decay li...

  17. Excitation-energy dependence of the nuclear fission characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Baba, H.; Saito, T.; Takahashi, N. [Osaka City Univ. (Japan). Faculty of Science] [and others

    1996-03-01

    It is known that the width parameter of the fragment mass yield distribution follows a beautiful systematics with respect to the excitation energy. According to this systematics, the fission characteristics following the systematics should disappear when the excitation energy Ex goes down to 14 MeV. The present purpose is to elucidate if, where, how and why a transition takes place in the fission characteristics of the asymmetric fission of light actinide elements. Two types of experiments are performed, one is the double-energy measurement of the kinetic energies of complementary fragments in the thermal-neutron fission of {sup 235,233}U and proton-induced fission of {sup 238}U at 13.3- and 15.7-MeV excitations, and the other is the radiochemical study of proton-induced fission and photofission of {sup 238}U at various excitation energies. In conclusion, it has demonstrated that there are two distinctive fission mechanisms in the low-energy fission of light actinide elements and the transition between them takes place around 14-MeV excitation. The characteristics of proton fission and photofission in the energy range lower than the above transition point are the essentially the same as those of thermal-neutron fission and also spontaneous fission. The results of GDR fission indicates the fission in the high-energy side starts from the nuclear collective states, whereas the lower-energy fission is of non-collective nature. It is likely that thermal-neutron fission is rather of the barrier-penetrating type like spontaneous fission than the threshold fission. (S.Y.)

  18. Fusion-fission study at IUAC: Recent results

    Science.gov (United States)

    Pullanhiotan, Sugathan

    2016-10-01

    Several properties observed in heavy ion induced fission led to the conclusion that fission is not always originated from fully equilibrated compound nucleus. Soon after the collision of two nuclei, it forms a di-nuclear system than can fission before a compound nucleus is formed. This process termed quasi-fission is a major hurdle to the formation of heavier elements by fusion. Fission originated before complete equilibration showed anomalously large angular anisotropy and mass distribution wider than what is expected from compound nucleus fission. The standard statistical model fails to predict the outcome of quasi-fission and currently no dynamical model is fully developed to predict all the features of quasi-fission. Though much progress has been made in recent times, a full understanding of the fission dynamics is still missing. Experiments identifying the influence of entrance channel parameters on dynamics of fusion-fission showed contrasting results. At IUAC accelerator facility many experiments have been performed to make a systematic study of fission dynamics using mass distribution, angular distribution and neutron multiplicity measurements in mass region around A ∼ 200. Recent measurement on mass distribution of fission fragment from reaction 19 F +206,208 Pb around fusion barrier energy showed the influence of multi-mode fission in enhancing the mass variance at low excitation energy. In this talk I will present some of these results.

  19. Karakteristik dan Aktivitas Antibakteri Scaffold Membran Cangkang Telur yang Diaktivasi Karbonat Apatit

    Directory of Open Access Journals (Sweden)

    Mirantini Aprilisna

    2015-06-01

    membran cangkang telur + karbonat apatit + SBF selama 7 hari, sampel D membran cangkang telur + karbonat apatit + SBF selama 14 hari, dan sampel E membran cangkang telur + karbonat apatit + SBF selama 21 hari. Uji sampel yaitu karakterisasi menggunakan ATR FTIR dan SEM, serta uji aktivitas antibakteri menggunakan metode difusi. Hasil karakterisasi SEM menunjukkan pori-pori serat 10-20μm pada semua sampel, ATR FTIR sampel B, C, D, E menunjukkan peningkatan gugus apatit dibanding sampel A. Pengujian antibakteri terhadap Staphylococcus aureus menunjukkan zona bening pada setiap sampel. Perhitungan jumlah koloni setiap sampel yaitu terbanyak koloninya sampel A ±78x105 CFU/ml, dan paling sedikit koloninya sampel B ±14x105 CFU/ml. Kesimpulan penelitian ini yaitu karakteristik dan aktivitas antibakteri scaffold membran cangkang telur yang diaktivasi karbonat apatit mengandung bahan bioaktif, bersifat biodegradasi dan menunjukkan aktivitas antibakteri.   Characteristic And Antibacterial Activity Of Egg-Shell Membrane Scaffold Activated By Carbonate Apatite. The loss of bone structure that can be caused by periodontal disease and trauma can be treated by installation of graft. The installation of graft is vulnerable to bacterial invasion, so that the alternative is to make a scaffold with antibacterial activity. Scaffold manufacturing in engineering system must have biocompatible, biodegradable, and bioactive properties. This research used egg-shell membrane (ESM as scaffold template, alginate, chitosan, carbonate apatite, and SBF solution. The purpose of this research is to know the characteristics, and antibacterial activity of eggshell membrane scaffold which is activated by carbonate apatite. This research used laboratory experimental method by dividing the samples into five groups that were ESM as sample A, ESM with carbonate apatite as sample B, ESM with carbonate apatite soaked in SBF sol for 7days as sample C, ESM with carbonate apatite soaked in

  20. Study on fission blanket fuel cycling of a fusion-fission hybrid energy generation system

    Science.gov (United States)

    Zhou, Z.; Yang, Y.; Xu, H.

    2011-10-01

    This paper presents a preliminary study on neutron physics characteristics of a light water cooled fission blanket for a new type subcritical fusion-fission hybrid reactor aiming at electric power generation with low technical limits of fission fuel. The major objective is to study the fission fuel cycling performance in the blanket, which may possess significant impacts on the feasibility of the new concept of fusion-fission hybrid reactor with a high energy gain (M) and tritium breeding ratio (TBR). The COUPLE2 code developed by the Institute of Nuclear and New Energy Technology of Tsinghua University is employed to simulate the neutronic behaviour in the blanket. COUPLE2 combines the particle transport code MCNPX with the fuel depletion code ORIGEN2. The code calculation results show that soft neutron spectrum can yield M > 20 while maintaining TBR >1.15 and the conversion ratio of fissile materials CR > 1 in a reasonably long refuelling cycle (>five years). The preliminary results also indicate that it is rather promising to design a high-performance light water cooled fission blanket of fusion-fission hybrid reactor for electric power generation by directly loading natural or depleted uranium if an ITER-scale tokamak fusion neutron source is achievable.

  1. Nuclear fission problem and Langevin equation

    Directory of Open Access Journals (Sweden)

    M Sakhaee

    2011-12-01

    Full Text Available  A combined dynamical and statistical model for fission was employed in our calculation. There is no doubt that a Langevin description plus a Monte Carlo treatment of the evaporation processes provide the most adequate dynamical description. In this paper, we would consider a strongly shaped dependent friction force and we use the numerical method rather than the analytical one. The objective of this article is to calculate the time dependent fission widths of the 224Th nucleus. The fission widths were calculated with both chaos-weighted wall friction (CWWF and wall friction (WF dissipations. The calculations are repeated for 100000 trajectories. The result was compared to the others' work. We use nuclear elongation coordinate with time and it is necessary to repeat the small steps many times to improve the accuracy.

  2. Energy partition in low energy fission

    CERN Document Server

    Mirea, M

    2011-01-01

    The intrinsic excitation energy of fission fragments is dynamically evaluated in terms of the time dependent pairing equations. These equations are corroborated with two conditions. One of them fixes the number of particles and the another separates the pairing active spaces associated to the two fragments in the vicinity of the scission configuration. The fission path is obtained in the frame of the macroscopic-microscopic model. The single particle level schemes are obtained within the two center Woods-Saxon shell model. It is shown that the available intrinsic dissipated energy is not shared proportionally to the masses of the two fission fragments. If the heavy fragment possesses nucleon numbers close to the magic ones, the accumulated intrinsic excitation energy is lower than that of the light fragment.

  3. Solar vs. Fission Surface Power for Mars

    Science.gov (United States)

    Rucker, Michelle A.; Oleson, Steve; George, Pat; Landis, Geoffrey A.; Fincannon, James; Bogner, Amee; Jones, Robert E.; Turnbull, Elizabeth; Martini, Michael C.; Gyekenyesi, John Z.; Colozza, Anthony J.; Schmitz, Paul C.; Packard, Thomas W.

    2016-01-01

    A multi-discipline team of experts from the National Aeronautics and Space Administration (NASA) developed Mars surface power system point design solutions for two conceptual missions. The primary goal of this study was to compare the relative merits of solar- versus fission-powered versions of each surface mission. First, the team compared three different solar power options against a fission power system concept for a sub-scale, uncrewed demonstration mission. The 4.5 meter (m) diameter pathfinder lander's primary mission would be to demonstrate Mars entry, descent, and landing techniques. Once on the Martian surface, the lander's In Situ Resource Utilization (ISRU) payload would demonstrate liquid oxygen propellant production using atmospheric resources. For the purpose of this exercise, location was assumed to be at the Martian equator. The three solar concepts considered included a system that only operated during daylight hours (at roughly half the daily propellant production rate of a round-the-clock fission design), a battery-augmented system that operated through the night (matching the fission concept's propellant production rate), and a system that operated only during daylight, but at a higher rate (again, matching the fission concept's propellant production rate). Including 30% mass growth allowance, total payload masses for the three solar concepts ranged from 1,116 to 2,396 kg, versus the 2,686 kg fission power scheme. However, solar power masses are expected to approach or exceed the fission payload mass at landing sites further from the equator, making landing site selection a key driver in the final power system decision. The team also noted that detailed reliability analysis should be performed on daytime-only solar power schemes to assess potential issues with frequent ISRU system on/off cycling. Next, the team developed a solar-powered point design solution for a conceptual four-crew, 500-day surface mission consisting of up to four landers per

  4. Prompt fission neutron emission: Problems and challenges

    Directory of Open Access Journals (Sweden)

    Hambsch F.-J.

    2013-12-01

    Full Text Available This paper presents some of the challenges ahead of us even after 75 years of the discovery of the fission process and large progress made since then. The focus is on application orientation, which requires improved measurements on fission cross-sections and neutron and γ-ray multiplicities. Experimental possibilities have vastly improved the past decade leading to developments of highly sophisticated detector systems and the use of digital data acquisition and signal processing. The development of innovative fast nuclear reactor technology needs improved respective nuclear data. Advancements in theoretical modelling also require better experimental data. Theory has made progress in calculating fission fragment distributions (i.e. GEF code as well as prompt neutron and γ-ray emission to catch up with the improved experiments.

  5. Antiproton Induced Fission and Fragmentation of Nuclei

    CERN Multimedia

    2002-01-01

    The annihilation of slow antiprotons with nuclei results in a large highly localized energy deposition primarily on the nuclear surface. \\\\ \\\\ The study of antiproton induced fission and fragmentation processes is expected to yield new information on special nuclear matter states, unexplored fission modes, multifragmentation of nuclei, and intranuclear cascades.\\\\ \\\\ In order to investigate the antiproton-nucleus interaction and the processes following the antiproton annihilation at the nucleus, we propose the following experiments: \\item A)~Measurement of several fragments from fission and from multifragmentation in coincidence with particle spectra, especially neutrons and kaons. \\item B)~Precise spectra of $\\pi$, K, n, p, d and t with time-of-flight techniques. \\item C)~Installation of the Berlin 4$\\pi$ neutron detector with a 4$\\pi$ Si detector placed inside for fragments and charged particles. This yields neutron multiplicity distributions and consequently distributions of thermal excitation energies and...

  6. Dissipative dynamics in quasi-fission

    CERN Document Server

    Oberacker, V E; Simenel, C

    2014-01-01

    Quasi-fission is the primary reaction mechanism that prevents the formation of superheavy elements in heavy-ion fusion experiments. Employing the time-dependent density functional theory approach we study quasi-fission in the systems $^{40,48}$Ca+$^{238}$U. Results show that for $^{48}$Ca projectiles the quasi-fission is substantially reduced in comparison to the $^{40}$Ca case. This partly explains the success of superheavy element formation with $^{48}$Ca beams. For the first time, we also calculate the repartition of excitation energies of the two fragments in a dynamic microscopic theory. The system is found in quasi-thermal equilibrium only for reactions with $^{40}$Ca. The differences between both systems are interpreted in terms of initial neutron to proton asymmetry of the colliding partners.

  7. Fission Enhanced diffusion of uranium in zirconia

    CERN Document Server

    Bérerd, N; Moncoffre, N; Sainsot, P; Faust, H; Catalette, H

    2005-01-01

    This paper deals with the comparison between thermal and Fission Enhanced Diffusion (FED) of uranium into zirconia, representative of the inner face of cladding tubes. The experiments under irradiation are performed at the Institut Laue Langevin (ILL) in Grenoble using the Lohengrin spectrometer. A thin $^{235}UO\\_2$ layer in direct contact with an oxidized zirconium foil is irradiated in the ILL high flux reactor. The fission product flux is about 10$^{11}$ ions cm$^{-2}$ s$^{-1}$ and the target temperature is measured by an IR pyrometer. A model is proposed to deduce an apparent uranium diffusion coefficient in zirconia from the energy distribution broadening of two selected fission products. It is found to be equal to 10$^{-15}$ cm$^2$ s$^{-1}$ at 480$\\circ$C and compared to uranium thermal diffusion data in ZrO$\\_2$ in the same pressure and temperature conditions. The FED results are analysed in comparison with literature data.

  8. Phase Transition Induced Fission in Lipid Vesicles

    CERN Document Server

    Leirer, C; Myles, V M; Schneider, M F

    2010-01-01

    In this work we demonstrate how the first order phase transition in giant unilamellar vesicles (GUVs) can function as a trigger for membrane fission. When driven through their gel-fluid phase transition GUVs exhibit budding or pearl formation. These buds remain connected to the mother vesicle presumably by a small neck. Cooling these vesicles from the fluid phase (T>Tm) through the phase transition into the gel state (Tfission of the neck, while the mother vesicle remains intact. Pearling tubes which formed upon heating break-up and decay into multiple individual vesicles which then diffuse freely. Finally we demonstrate that mimicking the intracellular bulk viscosity by increasing the bulk viscosity to 40cP does not affect the overall fission process, but leads to a significant decrease in size of the released vesicles.

  9. Research on Nuclear Reaction Network Equation for Fission Product Nuclides

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Nuclear Reaction Network Equation calculation system for fission product nuclides was developed. With the system, the number of the fission product nuclides at different time can be calculated in the different neutron field intensity and neutron energy spectra

  10. Solar Versus Fission Surface Power for Mars

    Science.gov (United States)

    Rucker, Michelle A.; Oleson, Steve; George, Pat; Landis, Geoffrey A.; Fincannon, James; Bogner, Amee; Jones, Robert E.; Turnbull, Elizabeth; McNatt, Jeremiah; Martini, Michael C.; Gyekenyesi, John Z.; Colozza, Anthony J.; Schmitz, Paul C.; Packard, Thomas W.

    2016-01-01

    A multi-discipline team of experts from the National Aeronautics and Space Administration (NASA) developed Mars surface power system point design solutions for two conceptual missions to Mars using In-situ resource utilization (ISRU). The primary goal of this study was to compare the relative merits of solar- versus fission-powered versions of each surface mission. First, the team compared three different solar-power options against a fission power system concept for a sub-scale, uncrewed demonstration mission. This “pathfinder” design utilized a 4.5 meter diameter lander. Its primary mission would be to demonstrate Mars entry, descent, and landing techniques. Once on the Martian surface, the lander’s ISRU payload would demonstrate liquid oxygen propellant production from atmospheric resources. For the purpose of this exercise, location was assumed to be at the Martian equator. The three solar concepts considered included a system that only operated during daylight hours (at roughly half the daily propellant production rate of a round-the-clock fission design), a battery-augmented system that operated through the night (matching the fission concept’s propellant production rate), and a system that operated only during daylight, but at a higher rate (again, matching the fission concept’s propellant production rate). Including 30% mass growth allowance, total payload masses for the three solar concepts ranged from 1,128 to 2,425 kg, versus the 2,751 kg fission power scheme. However, solar power masses increase as landing sites are selected further from the equator, making landing site selection a key driver in the final power system decision. The team also noted that detailed reliability analysis should be performed on daytime-only solar power schemes to assess potential issues with frequent ISRU system on/off cycling.

  11. The Identification and Synthesis of Lead Apatite Minerals Formed in Lead Water Pipes

    Directory of Open Access Journals (Sweden)

    Jeremy D. Hopwood

    2016-01-01

    Full Text Available Phosphate is added to drinking water in the UK to minimise the release of lead from lead water pipes. The phosphate encourages the formation of insoluble lead apatites on the walls of the pipe. Hydroxylpyromorphite Pb5(PO43OH is the lead apatite that is most often used to model lead levels in tap water; however, its presence has not been confirmed. Our aims were to identify the lead pipe apatite and synthesise it. The synthetic mineral would then be used in future solubility studies to produce better predictions of lead levels in tap water. XRD and FTIR were used to characterise the minerals on a range of lead pipes. Pyromorphite and hydroxylpyromorphite were absent and instead a range of mixed calcium lead apatites were present. For every five lead ions in the general formula Pb5(PO43X between one and two ions were replaced with calcium and there was evidence of substitution of PO43- by either CO32- or HPO42-. Calcium lead apatites with similar unit cell dimensions to those found on lead water pipes were then synthesised. The calcium : lead ratio in these reaction mixtures was in excess of 500 : 1 and the resulting crystals were shown by TEM to be nanosized rods and flakes. The synthetic apatites that most closely resembled the unit cell dimensions of the apatites on lead water pipes were shown to be Pb3.4Ca1.3(PO43Cl0.03OH0.97, Pb3.6Ca1.2(PO43Cl0.07OH0.93, and Pb3.6Ca1.2(PO43Cl0.27OH0.73.

  12. Amelogenin as a promoter of nucleation and crystal growth of apatite

    Science.gov (United States)

    Uskoković, Vuk; Li, Wu; Habelitz, Stefan

    2011-02-01

    Human dental enamel forms over a period of 2-4 years by substituting the enamel matrix, a protein gel mostly composed of a single protein, amelogenin with fibrous apatite nanocrystals. Self-assembly of amelogenin and the products of its selective proteolytic digestion are presumed to direct the growth of apatite fibers and their organization into bundles that eventually comprise the mature enamel, the hardest tissue in the mammalian body. This work aimed to establish the physicochemical and biochemical conditions for the growth of apatite crystals under the control of a recombinant amelogenin matrix (rH174) in combination with a programmable titration system. The growth of apatite substrates was initiated in the presence of self-assembling amelogenin particles. A series of constant titration rate experiments was performed that allowed for a gradual increase of the calcium and/or phosphate concentrations in the protein suspensions. We observed a significant amount of apatite crystals formed on the substrates following the titration of rH174 sols that comprised the initial supersaturation ratio equal to zero. The protein layers adsorbed onto the substrate apatite crystals were shown to act as promoters of nucleation and growth of calcium phosphates subsequently formed on the substrate surface. Nucleation lag time experiments have showed that rH174 tends to accelerate precipitation from metastable calcium phosphate solutions in proportion to its concentration. Despite their mainly hydrophobic nature, amelogenin nanospheres, the size and surface charge properties of which were analyzed using dynamic light scattering, acted as a nucleating agent for the crystallization of apatite. The biomimetic experimental setting applied in this study proves as convenient for gaining insight into the fundamental nature of the process of amelogenesis.

  13. BMP-2 gene-fibronectin-apatite composite layer enhances bone formation

    Directory of Open Access Journals (Sweden)

    Sogo Yu

    2011-08-01

    Full Text Available Abstract Background Safe and efficient gene transfer systems are needed for tissue engineering. We have developed an apatite composite layer including the bone morphogenetic protein-2 (BMP-2 gene and fibronectin (FB, and we evaluated its ability to induce bone formation. Methods An apatite composite layer was evaluated to determine the efficiency of gene transfer to cells cultured on it. Cells were cultured on a composite layer including the BMP-2 gene and FB, and BMP-2 gene expression, BMP-2 protein concentrations, alkaline phosphatase (ALP activity, and osteocalcin (OC concentrations were measured. A bone defect on the cranium of rats was treated with hydroxyapatite (HAP-coated ceramic buttons with the apatite composite layer including the BMP-2 gene and FB (HAP-BMP-FB. The tissue concentration of BMP-2, bone formation, and the expression levels of the BMP-2, ALP, and OC genes were all quantified. Results The apatite composite layer provided more efficient gene transfer for the cultured cells than an apatite composite layer without FB. The BMP-2 concentration was approximately 100~600 pg/mL in the cell-culture medium. Culturing the cells on the apatite composite layer for 27 days increased ALP activity and OC concentrations. In animal experiments, the tissue concentrations of BMP-2 were over 100 pg/mg in the HAP-BMP-FB group and approximately 50 pg/mg in the control groups. Eight weeks later, bone formation was more enhanced in the HAP-BMP-FB group than in the control groups. In the tissues surrounding the HAP button, the gene expression levels of ALP and OC increased. Conclusion The BMP-2 gene-FB-apatite composite layer might be useful for bone engineering.

  14. Fabrication and in vitro characterization of magnetic hydroxycarbonate apatite coatings with hierarchically porous structures.

    Science.gov (United States)

    Guo, Yaping; Zhou, Yu; Jia, Dechang; Meng, Qingchang

    2008-07-01

    Hydroxycarbonate apatite/Fe(3)O(4) composite coatings (MHACs) with hierarchically porous structures were fabricated by electrophoretic deposition of CaCO(3)/Fe(3)O(4) particles on Ti6Al4V substrates followed by treatment with phosphate buffer solution (PBS) at 37 degrees C. The effects of Fe(3)O(4) on the conversion rate of calcium carbonate to hydroxycarbonate apatite and the porous structures and in vitro bioactivity of MHACs were investigated. After soaking CaCO(3)/Fe(3)O(4) coatings in PBS, hydroxycarbonate apatite nucleates heterogeneously on the surfaces of CaCO(3)/Fe(3)O(4) particles and forms a plate-like structure. Fe(3)O(4) increases the velocity of nucleus formation of hydroxycarbonate apatite. After soaking for 1day, the percentage of unreacted calcium carbonate for MHACs is approximately 9.1%, lower than the approximately 41.0% for hydroxycarbonate apatite coatings (HCACs). As the CaCO(3)/Fe(3)O(4) coatings are converted to MHACs, macropores with a pore size of approximately 4mum on the coatings and mesopores with a pore size of approximately 3.9nm within the hydroxycarbonate apatite plates are formed. The mesopores remain in the MHACs after treatment with PBS for 9 days, while they disappear in the HCACs. Simulated body fluid immersion tests reveal that Fe(3)O(4) improves the in vitro bioactivity of biocoatings. The amount of bone-like apatite precipitated on the surfaces of MHACs is greater than that on the surfaces of HCACs.

  15. A fission-fragment-sensitive target for X-ray spectroscopy in neutron-induced fission

    CERN Document Server

    Ethvignot, T; Giot, L; Casoli, P; Nelson, R O

    2002-01-01

    A fission-fragment-sensitive detector built for low-energy photon spectroscopy applications at the WNR 'white' neutron source at Los Alamos is described. The detector consists of eight layers of thin photovoltaic cells, onto which 1 mg/cm sup 2 of pure sup 2 sup 3 sup 8 U is deposited. The detector serves as an active target to select fission events from background and other reaction channels. The fairly small thickness of the detector with respect to transmission of 20-50 keV photons permits the measurement of prompt fission-fragment X-rays. Results with the GEANIE photon spectrometer are presented.

  16. Uranium arc fission reactor for space propulsion

    Science.gov (United States)

    Watanabe, Yoichi; Maya, Isaac; Vitali, Juan; Appelbaum, Jacob; Schneider, Richard T.

    1991-01-01

    Combining the proven technology of solid core reactors with uranium arc confinement and non-equilibrium ionization by fission fragments can lead to an attractive propulsion system which has a higher specific impulse than a solid core propulsion system and higher thrust than an electric propulsion systems. A preliminary study indicates that a system with 300 MW of fission power can achieve a gas exhaust velocity of 18,000 m/sec and a thrust of 10,000 Newtons utilizing a magnetohydrodynamic generator and accelerator. An experimental program is underway to examine the major mass and energy transfer issues.

  17. Actinide and fission product separation and transmutation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-07-01

    The second international information exchange meeting on actinide and fission product separation and transmutation, took place in Argonne National Laboratory in Illinois United States, on 11-13 November 1992. The proceedings are presented in four sessions: Current strategic system of actinide and fission product separation and transmutation, progress in R and D on partitioning processes wet and dry, progress in R and D on transmutation and refinements of neutronic and other data, development of the fuel cycle processes fuel types and targets. (A.L.B.)

  18. Ionization Chamber for Prompt Fission Neutron Investigations

    OpenAIRE

    ZEYNALOV Sh.; ZEYNALOVA O. V.; Hambsch, Franz-Josef; Sedyshev, P.; SHVETSOV V.

    2014-01-01

    In this work we report recent achievements in design of twin back-to-back ionization chamber (TIC) for fission fragment (FF) mass and kinetic energy measurement. Correlated FF kinetic energies, their masses and the angle of FF in respect to the axes in 3D Cartesian coordinates can be determined from analysis of the heights and shapes of the pulses induced by the fission fragments on the anodes of TIC. Anodes of TIC were designed as consisting of isolated strips each having independent electro...

  19. Fission Yeast Cell Cycle Synchronization Methods.

    Science.gov (United States)

    Tormos-Pérez, Marta; Pérez-Hidalgo, Livia; Moreno, Sergio

    2016-01-01

    Fission yeast cells can be synchronized by cell cycle arrest and release or by size selection. Cell cycle arrest synchronization is based on the block and release of temperature-sensitive cell cycle mutants or treatment with drugs. The most widely used approaches are cdc10-129 for G1; hydroxyurea (HU) for early S-phase; cdc25-22 for G2, and nda3-KM311 for mitosis. Cells can also be synchronized by size selection using centrifugal elutriation or a lactose gradient. Here we describe the methods most commonly used to synchronize fission yeast cells.

  20. Alpha decay from fission isomeric states

    Energy Technology Data Exchange (ETDEWEB)

    Poenaru, D.N.; Ivascu, M. (Institutul de Fizica si Inginerie Nucleara, Bucharest (Romania))

    1981-07-01

    Alpha-decay half-lives from shape isomeric states of some even-even isotopes of U, Pu and Cm nuclei are calculated by using fission theory in the parametrisation of a spheroid intersected with a sphere. The potential barrier was calculated in the framework of the liquid-drop model of Myers and Swiatecki (Art. Fys.; 36: 343 (1967)) extended for systems with different charge densities; a phenomenological shell correction was introduced. The WKB computed lifetimes are many orders of magnitude longer than that of the spontaneous fission process, in agreement with experimental results.

  1. Optimally moderated nuclear fission reactor and fuel source therefor

    Science.gov (United States)

    Ougouag, Abderrafi M.; Terry, William K.; Gougar, Hans D.

    2008-07-22

    An improved nuclear fission reactor of the continuous fueling type involves determining an asymptotic equilibrium state for the nuclear fission reactor and providing the reactor with a moderator-to-fuel ratio that is optimally moderated for the asymptotic equilibrium state of the nuclear fission reactor; the fuel-to-moderator ratio allowing the nuclear fission reactor to be substantially continuously operated in an optimally moderated state.

  2. Energy Partition in n+233U Fission Reaction

    Institute of Scientific and Technical Information of China (English)

    CHEN; Yong-jing; LIU; Ting-jin; SHU; Neng-chuan

    2012-01-01

    <正>The partition of the total excitation energy between the fission fragments for the n+233U fission reactions are analyzed with a semi-empirical model, and it is a key point for calculating the prompt fission neutron spectrum, and it is still a long-standing problem for nuclear fission, and attracts more and more attention. With the available experimental data, such as the average total number of emitted neutrons, the

  3. Overview of research by the fission group in Trombay

    Indian Academy of Sciences (India)

    R K Chourdhury

    2015-08-01

    Nuclear fission studies in Trombay began nearly six decades ago, with the commissioning of the APSARA research reactor. Early experimental work was based on mass, kinetic energy distributions, neutron and X-ray emission in thermal neutron fission of 235U, which were carried out with indigenously developed detectors and electronics instrumentation. With the commissioning of CIRUS reactor and the availability of higher neutron flux, advanced experiments were carried out on ternary fission, pre-scission neutron emission, fragment charge distributions, quarternary fission, etc. In the late eighties, heavy-ion beams from the pelletron-based medium energy heavy-ion accelerator were available, which provided a rich variety of possibilities in nuclear fission studies. Pioneering work on fragment angular distributions, fission time-scales, transfer-induced fission, -ray multiplicities and mass–energy correlations were carried out, providing important information on the dynamics of the fission process. More recently, work on fission fragment -ray spectroscopy has been initiated, to understand the nuclear structure aspects of the neutron-rich fission fragment nuclei. There have also been parallel efforts to carry out theoretical studies in the areas of shell effects, superheavy nuclei, fusion–fission dynamics, fragment angular distributions, etc. to complement the experimental studies. This paper will provide a glimpse of the work carried out by the fission group at Trombay in the above-mentioned topics.

  4. Developing an "atomic clock" for fission lifetime measurements

    NARCIS (Netherlands)

    Wilschut, H.W.E.M.; Kravchuk, V.

    2004-01-01

    The relevance of measuring fission lifetimes of hot nuclei is briefly discussed. It is shown that K X-ray emission prior to fission can be used to measure fission lifetimes. The preparation of the K-shell hole, the simultaneous nuclear excitation, and the analysis of the X-ray spectra is described.

  5. SYMMETRICAL AND ASYMMETRIC TERNARY FISSION OF HOT NUCLEI

    NARCIS (Netherlands)

    SIWEKWILCZYNSKA, K; WILCZYNSKI, J; LEEGTE, HKW; SIEMSSEN, RH; WILSCHUT, HW; GROTOWSKI, K; PANASIEWICZ, A; SOSIN, Z; WIELOCH, A

    1993-01-01

    Emission of a particles accompanying fusion-fission processes in the Ar-40 + Th-232 reaction at E(Ar-40) = 365 MeV was studied in a wide range of in-fission-plane and out-of-plane angles. The exact determination of the emission angles of both fission fragments combined with the time-of-flight measur

  6. Mass Distribution Measurement of 252Cf Spontaneous Fission

    Institute of Scientific and Technical Information of China (English)

    LIU; Shi-long; YANG; Yi; ZHANG; Chun-li; HAN; Hong-yin

    2015-01-01

    The E-v method of measuring the kinetic energy(E)and velocity(v)of outgoing fission products has been utilized,with the goal of measuring the mass resolution better than 1atomic mass units(amu),and could identify every mass for light fission products of unsymmetrical fission.This work measured mass yield distribution

  7. Design and Simulation of High Radioactivity Fission Ionization Chamber

    Institute of Scientific and Technical Information of China (English)

    WANG; Qi

    2012-01-01

    <正>It is great effect that the fission neutron release in 239Pu(n, 2n) cross section measurement by using multi-unit gadolinium loaded liquid scintillation detector system, for the 239Pu fission cross section is larger than (n, 2n) cross section one order of magnitude. In order to deduct the effect of fission neutrons,

  8. Fission barrier heights in the A ∼ 200 mass region

    Indian Academy of Sciences (India)

    K Mahata

    2015-08-01

    Statistical model analysis is carried out for - and -induced fission reactions using a consistent description for fission barrier and level density in A ∼ 200 mass region. A continuous damping of shell correction with excitation energy is considered. Extracted fission barriers agree well with the recent microscopic–macroscopic model. The shell corrections at the saddle point were found to be insignificant.

  9. SPIDER Progress Towards High Resolution Correlated Fission Product Data

    Science.gov (United States)

    Shields, Dan; Meierbachtol, Krista; Tovesson, Fredrik; Arnold, Charles; Blackeley, Rick; Bredeweg, Todd; Devlin, Matt; Hecht, Adam; Jandel, Marian; Jorgenson, Justin; Nelson, Ron; White, Morgan; Spider Team

    2014-09-01

    The SPIDER detector (SPectrometer for Ion DEtermination in fission Research) is under development with the goal of obtaining high-resolution, high-efficiency, correlated fission product data needed for many applications including the modeling of next generation nuclear reactors, stockpile stewardship, and the fundamental understanding of the fission process. SPIDER simultaneously measures velocity and energy of both fission products to calculate fission product yields (FPYs), neutron multiplicity (ν), and total kinetic energy (TKE). A detailed description of the prototype SPIDER detector components will be presented. Characterization measurements with alpha and spontaneous fission sources will also be discussed. LA-UR-14-24875. The SPIDER detector (SPectrometer for Ion DEtermination in fission Research) is under development with the goal of obtaining high-resolution, high-efficiency, correlated fission product data needed for many applications including the modeling of next generation nuclear reactors, stockpile stewardship, and the fundamental understanding of the fission process. SPIDER simultaneously measures velocity and energy of both fission products to calculate fission product yields (FPYs), neutron multiplicity (ν), and total kinetic energy (TKE). A detailed description of the prototype SPIDER detector components will be presented. Characterization measurements with alpha and spontaneous fission sources will also be discussed. LA-UR-14-24875. This work is in part supported by LANL Laboratory Directed Research and Development Projects 20110037DR and 20120077DR.

  10. Fission Matrix Capability for MCNP Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Carney, Sean E. [Los Alamos National Laboratory; Brown, Forrest B. [Los Alamos National Laboratory; Kiedrowski, Brian C. [Los Alamos National Laboratory; Martin, William R. [Los Alamos National Laboratory

    2012-09-05

    In a Monte Carlo criticality calculation, before the tallying of quantities can begin, a converged fission source (the fundamental eigenvector of the fission kernel) is required. Tallies of interest may include powers, absorption rates, leakage rates, or the multiplication factor (the fundamental eigenvalue of the fission kernel, k{sub eff}). Just as in the power iteration method of linear algebra, if the dominance ratio (the ratio of the first and zeroth eigenvalues) is high, many iterations of neutron history simulations are required to isolate the fundamental mode of the problem. Optically large systems have large dominance ratios, and systems containing poor neutron communication between regions are also slow to converge. The fission matrix method, implemented into MCNP[1], addresses these problems. When Monte Carlo random walk from a source is executed, the fission kernel is stochastically applied to the source. Random numbers are used for: distances to collision, reaction types, scattering physics, fission reactions, etc. This method is used because the fission kernel is a complex, 7-dimensional operator that is not explicitly known. Deterministic methods use approximations/discretization in energy, space, and direction to the kernel. Consequently, they are faster. Monte Carlo directly simulates the physics, which necessitates the use of random sampling. Because of this statistical noise, common convergence acceleration methods used in deterministic methods do not work. In the fission matrix method, we are using the random walk information not only to build the next-iteration fission source, but also a spatially-averaged fission kernel. Just like in deterministic methods, this involves approximation and discretization. The approximation is the tallying of the spatially-discretized fission kernel with an incorrect fission source. We address this by making the spatial mesh fine enough that this error is negligible. As a consequence of discretization we get a

  11. Apatite formation behaviour during metasomatism in the Bathtub Intrusion (Babbitt deposit, Duluth Complex, USA)

    Science.gov (United States)

    Raič, Sara; Mogessie, Aberra; Krenn, Kurt; Hauzenberger, Christoph A.; Tropper, Peter

    2016-04-01

    The mineralized troctolitic Bathtub intrusion (Duluth Complex, NE-Minnesota) is known for its famous Cu-Ni-Sulfide±PGM Babbitt deposit, where platinum group minerals (PGMs) are either hosted by primary magmatic sulfides (base metal sulfides) or associated with hydrothermally altered portions. This secondary generation of PGMs is present in alteration patches and suggests the involvement of hydrothermal fluids in the mobilization of platinum-group elements (PGEs). Accessory fluorapatite in these samples reveals besides H2O- and CO2-rich primary fluid inclusions, textural and compositional variations that also record magmatic and metasomatic events. Based on detailed back-scattered electron imaging (BSE) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS), a primary magmatic origin is reflected by homogeneous or zoned grains, where zoning patterns are either concentric or oscillatory, with respect to LREE. Late magmatic to hydrothermal processes are indicated by grains with bright LREE-enriched rims or conversion textures with REE-enriched patches in the interior of the apatite. A metasomatic formation of monazite from apatite is documented by the presence of monazite inclusions in apatite and newly grown monazite at altered apatite rims. They formed by the release of REEs from the apatite during a fluid-induced alteration, based on the coupled substitution Ca2+ + P5+ = REE3+ + Si4+ (Rønsbo 1989; Rønsbo 2008). Samples with monazite inclusions in apatite further display occurrences of PGMs associated with hydrothermal alteration patches (chlorite + amphibole). The presence of H2O- and CO2-rich fluid inclusions in apatite, the metasomatically induced monazite growth, as well as the occurrence of PGMs in hydrothermally alteration zones, also suggest the involvement of aqueous chloride complexes in a H2O dominated fluid in the transportation of LREE and redistribution of the second generation of PGEs. Rønsbo, J.G. (1989): Coupled substitutions

  12. Bio-inspired citrate functionalized apatite coating on rapid prototyped titanium scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Peng [National engineering research center for tissue restoration and reconstruction, South China University of Technology, Guangzhou 510641 (China); Lu, Fang [School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006 (China); Zhu, Wenjun [Department of Prosthodontics, Guanghua School of Stomatology, Guang Dong Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055 (China); Wang, Di [National engineering research center for tissue restoration and reconstruction, South China University of Technology, Guangzhou 510641 (China); Zhu, Xiaojing [Department of Prosthodontics, Guanghua School of Stomatology, Guang Dong Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055 (China); Tan, Guoxin, E-mail: tanguoxin@126.com [Institute of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); Wang, Xiaolan [National engineering research center for tissue restoration and reconstruction, South China University of Technology, Guangzhou 510641 (China); Zhang, Yu; Li, Lihua [General Hospital of Guangzhou Military Command of PLA, Guangzhou 510010 (China); Ning, Chengyun, E-mail: imcyning@scut.edu.cn [National engineering research center for tissue restoration and reconstruction, South China University of Technology, Guangzhou 510641 (China)

    2014-09-15

    Highlights: • Designed and reproducible porous titanium scaffolds were produced. • Hydrophilic nanoporous film was built on scaffold. • Apatite coating was deposited on scaffold under the modulation of citrate ions. • Citrate ions could affect CO{sub 3}{sup 2−} incorporation in apatite coatings. - Abstract: Scaffold functionalized with appropriate osteogenic coatings can significantly improve implant-bone response. In this study, with designed model and optimized manufacture parameters, reproducible and precise titanium scaffolds were produced. Reconstructed three-dimensional image and sectional structure of the scaffold were examined by micro-computed tomography and relative software. Alkali treatment was carried out on these manufactured porous scaffolds to produce nanoporous hydrophilic film. After 6 days deposition in simulated body fluid (SBF) containing sodium citrate (SC-SBF), plate-like amorphous calcium phosphate (ACP) coating was deposited on scaffold surface. Ultrasonication tests qualitatively indicated an enhanced adhesion force of apatite coatings deposited in SC-SBF compared to that deposited in SBF. And the effect of citrate ions on the CO{sub 3}{sup 2−} incorporation rate in apatite coating was quantitatively examined by bending vibration of CO{sub 3}{sup 2−} at ∼874 cm{sup −1}. Results indicated the highest carbonate content was obtained at the citrate ion concentration of 6 × 10{sup −5} mol/L in SC-SBF. These three-dimensional porous titanium-apatite hybrid scaffolds are expected to find application in bone tissue regeneration.

  13. Simultaneous incorporation of magnesium and carbonate in apatite: effect on physico-chemical properties

    Directory of Open Access Journals (Sweden)

    Marcia S. Sader

    2013-01-01

    Full Text Available Synthetic apatites are widely used both in the dental and the orthopaedic fields due to their similarity in composition with the inorganic phase of hard tissues. Biologic apatites are not pure hydroxyapatite (HA, but are calcium-deficient apatites with magnesium and carbonate as minor but important substituents. The aim of the present study was to produce a more soluble biomaterial through the simultaneous substitution of magnesium and carbonate in the apatite structure to accelerate the degradation time in the body. The physico-chemical and dissolution properties of unsintered magnesium and carbonate-substituted apatite (MCAp with similar Mg/Ca molar ratio (0.03 and varying C/P molar ratio were evaluated. The resultant powders were characterised using several techniques, such as FTIR, TGA, XRD, ICP and SEM, while the release of calcium ions in a pH 6 solution was monitored using a Ca-ion selective electrode. The results showed a decrease of crystallite size and an increase in the release of calcium to the medium as the carbonate content in the samples increased.

  14. Formate incorporation in the structure of Ca-deficient apatite: Rietveld structure refinement

    Science.gov (United States)

    Wilson, R. M.; Elliott, J. C.; Dowker, S. E. P.

    2003-08-01

    Two sets of non-stoichiometric apatites (Ca-deficient apatites) were prepared from calcium phosphate solutions by homogeneous precipitation through the hydrolysis of formamide at 95°C. One set of products contained monetite (CaHPO 4) and apatite, whilst the second, with more formamide, contained only apatite. Rietveld whole pattern fitting structure refinements were undertaken on all samples, and chemical analyses, IR and NMR spectroscopy, on the second set of samples. The Ca/P mol ratio was 1.596. Rietveld analysis gave lattice parameters a=9.4729(20) and c=6.8855(9) Å and showed that Ca 2+ ions were lost exclusively from Ca2 sites, and that the PO 4 tetrahedron volume and P-O bonds were 4.4% and 1.4% smaller, respectively, than in hydroxyapatite (OHAp). Formate, HCO 2-, was clearly visible in the IR and NMR spectra, but the diffraction studies showed it was not present as a separate crystalline phase. Chemical analysis gave 5.8 wt % formate. We propose that the enlarged a-axis compared with OHAp ( a=9.4243(55) Å) and reduced PO 4 dimensions and P occupancy are, respectively, caused by the partial replacement of OH - and PO 43- ions in the structure by HCO 2- ions. These substitutions would parallel the similar known substitutions of CO 32- ions in precipitated carbonate apatites.

  15. Study of thermoluminescence properties of Eppawala apatite mineral and its suitability as a dosimetric material

    CERN Document Server

    Jayalath, A

    2000-01-01

    This study reports TL properties and the dosimetric properties of natural apatite mineral obtained from Eppawala Apatite ore in Sri Lanka. This mineral was used to study glow curve characteristics by using (a) the powder form of the raw mineral (b) sieved raw mineral and (c) the magnetically separated mineral. The glow curves of magnetically separated apatite showed two peaks. Low temperature peak at 120C, and a high temperature peak at 240C. The emission wavelength of the glow curve is 360 nm. The intensity of the 240C peak become stronger after annealing the mineral to about 180C. Apatite has glow peaks similar to other commonly used TL materials, such as synthetically prepared calcium sulphate:Dy and calcium sulphate:Tm show high intensity peak at 220C and low intensity peaks at 80C and 120C. However, the emission wavelengths of the main peaks are at 428nm and 452 nm for calcium sulphate:Dy and calcium sulphate: Tm respectively. Eppawala apatite mineral showed a linear response to both gamma and beta radia...

  16. High carbonate level of apatite in kidney stones implies infection, but is it predictive?

    Science.gov (United States)

    Englert, Kate M; McAteer, James A; Lingeman, James E; Williams, James C

    2013-10-01

    The presence of infectious microorganisms in urinary stones is commonly inferred from stone composition, especially by the presence of struvite in a stone. The presence of highly carbonated apatite has also been proposed as a marker of the presence of bacteria within a stone. We retrospectively studied 368 patients who had undergone percutaneous nephrolithotomy (PCNL), and who also had culture results for both stone and urine. Urine culture showed no association with stone mineral content, but stone culture was more often positive in struvite-containing stones (73 % positive) and majority apatite stones (65 %) than in other stone types (54 %, lower than the others, P carbonate content of apatite could be measured, carbonate in the apatite was weakly predictive of positive stone culture with an optimal cutoff value of 13.5 % carbonate (sensitivity 0.61, specificity 0.80). In positive cultures of stones (all mineral types combined), organisms that characteristically produce urease were present in 71 % of the cases, with no difference in this proportion among different types of stone. In summary, the type of mineral in the stone was predictive of positive stone culture, but this correlation is imperfect, as over half of non-struvite, non-apatite stones were found to harbor culturable organisms. We conclude that mineral type is an inadequate predictor of whether a stone contains infectious organisms, and that stone culture is more likely to provide information useful to the management of patients undergoing PCNL.

  17. Fission yeast meets a legend in Kobe: report of the Eighth International Fission Yeast Meeting.

    Science.gov (United States)

    Asakawa, Haruhiko; Yamamoto, Takaharu G; Hiraoka, Yasushi

    2015-12-01

    The Eighth International Fission Yeast Meeting, which was held at Ikuta Shrine Hall in Kobe, Japan, from 21 to 26 June 2015, was attended by 327 fission yeast researchers from 25 countries (190 overseas and 137 domestic participants). At this meeting, 124 talks were held and 145 posters were presented. In addition, newly developed database tools were introduced to the community during a workshop. Researchers shared cutting-edge knowledge across broad fields of study, ranging from molecules to evolution, derived from the superior model organism commonly used within the fission yeast community. Intensive discussions and constructive suggestions generated in this meeting will surely advance the understanding of complex biological systems in fission yeast, extending to general eukaryotes.

  18. Fission barriers and probabilities of spontaneous fission for elements with Z$\\geq$100

    CERN Document Server

    Baran, A; Reinhard, P -G; Robledo, L M; Staszczak, A; Warda, M

    2015-01-01

    This is a short review of methods and results of calculations of fission barriers and fission half-lives of even-even superheavy nuclei. An approvable agreement of the following approaches is shown and discussed: The macroscopic-microscopic approach based on the stratagem of the shell correction to the liquid drop model and a vantage point of microscopic energy density functionals of Skyrme and Gogny type selfconsistently calculated within Hartree-Fock-Bogoliubov method. Mass parameters are calculated in the Hartree-Fock-Bogoliubov cranking approximation. A short part of the paper is devoted to the nuclear fission dynamics. We also discuss the predictive power of Skyrme functionals applied to key properties of the fission path of $^{266}$Hs. It applies the standard techniques of error estimates in the framework of a $\\chi^2$ analysis.

  19. Fission Product Sorptivity in Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Tompson, Jr., Robert V. [Univ. of Missouri, Columbia, MO (United States); Loyalka, Sudarshan [Univ. of Missouri, Columbia, MO (United States); Ghosh, Tushar [Univ. of Missouri, Columbia, MO (United States); Viswanath, Dabir [Univ. of Missouri, Columbia, MO (United States); Walton, Kyle [Univ. of Missouri, Columbia, MO (United States); Haffner, Robert [Univ. of Missouri, Columbia, MO (United States)

    2015-04-01

    Both adsorption and absorption (sorption) of fission product (FP) gases on/into graphite are issues of interest in very high temperature reactors (VHTRs). In the original proposal, we proposed to use packed beds of graphite particles to measure sorption at a variety of temperatures and to use an electrodynamic balance (EDB) to measure sorption onto single graphite particles (a few μm in diameter) at room temperature. The use of packed beds at elevated temperature is not an issue. However, the TPOC requested revision of this initial proposal to included single particle measurements at elevated temperatures up to 1100 °C. To accommodate the desire of NEUP to extend the single particle EDB measurements to elevated temperatures it was necessary to significantly revise the plan and the budget. These revisions were approved. In the EDB method, we levitate a single graphite particle (the size, surface characteristics, morphology, purity, and composition of the particle can be varied) or agglomerate in the balance and measure the sorption of species by observing the changes in mass. This process involves the use of an electron stepping technique to measure the total charge on a particle which, in conjunction with the measured suspension voltages for the particle, allows for determinations of mass and, hence, of mass changes which then correspond to measurements of sorption. Accommodating elevated temperatures with this type of system required a significant system redesign and required additional time that ultimately was not available. These constraints also meant that the grant had to focus on fewer species as a result. Overall, the extension of the original proposed single particle work to elevated temperatures added greatly to the complexity of the proposed project and added greatly to the time that would eventually be required as well. This means that the bulk of the experimental progress was made using the packed bed sorption systems. Only being able to recruit one

  20. Fission in intermediate energy heavy ion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Wilhelmy, J.B.; Begemann-Blaich, M.; Blaich, T.; Boissevain, J.; Fowler, M.M.; Gavron, A.; Jacak, B.V.; Lysaght, P.S. (Los Alamos National Lab., NM (USA)); Britt, H.C.; Fields, D.J.; Hansen, L.F.; Lanier, R.G.; Massoletti, D.J.; Namboodiri, M.M.; Remington, B.A.; Sangster, T.C.; Struble, G.L.; Webb, M.L. (Lawrence Livermore National Lab., CA (USA)); Chan, Y.D.; Dacai, A.; Harmon, A.; Leyba, J.; Pouliot, J.; Stokstad, R.G. (Lawrence Berkeley Lab., CA (USA)); Hansen, O.; Levine, M.J.; Thorn, C.E.; Trautmann, W. (Brookhaven National Lab., Upton, NY (USA)); Dichter, B.; Kaufman, S.; Videbaek, F. (Argonne National Lab. (USA)); Fraenkel, Z.; Mamane, G. (Weizmann Inst. of Science, Rehovoth (Israel)); Cebra, D.; Westfall, G.D. (Michigan State Univ., East Lansing (USA))

    1989-10-09

    A systematic study of reaction mechanisms at intermediate energies (50-100 MeV/A) has been performed at the Lawrence Berkeley Laboratory's BeValac using medium weight projectiles on medium and heavy element targets. A gas and plastic phoswich detector system was employed which gave large geometric coverage and a wide dynamic response. The particles identified with the gas detectors could be characterized into three components - intermediate mass fragments (IMF), fission fragments (FF) and heavy residues (HR). Major observed features are: The reaction yields are similar in the 50 to 100 MeV/A range, central collisions have high multiplicty of IMF's with broad angular correlations consistent with a large participant region, effects of final state Coulomb interactions are observed and give information on the size and temporal behavior of the source, true fission yields are dependent on target fissility and correlated with relatively peripheral collisions. Analysis of fission and evaporation yields implies limiting conditions for which fission decay remains a viable deexcitation channel. (orig.).

  1. Propagation of a constant velocity fission wave

    Science.gov (United States)

    Deinert, Mark

    2011-10-01

    The ideal nuclear fuel cycle would require no enrichment, minimize the need fresh uranium, and produce few, if any, transuranic elements. Importantly, the latter goal would be met without the reprocessing. For purely physical reasons, no reactor system or fuel cycle can meet all of these objectives. However, a traveling-wave reactor, if feasible, could come remarkably close. The concept is simple: a large cylinder of natural (or depleted) uranium is subjected to a fast neutron source at one end, the neutrons would transmute the uranium downstream and produce plutonium. If the conditions were right, a self-sustaining fission wave would form, producing yet more neutrons which would breed more plutonium and leave behind little more than short-lived fission products. Numerical studies have shown that fission waves of this type are also possible. We have derived an exact solution for the propagation velocity of a fission wave through fertile material. The results show that these waves fall into a class of traveling wave phenomena that have been encountered in other systems. The solution places a strict conditions on the shapes of the flux, diffusive, and reactive profiles that would be required for such a phenomenon to persist. The results are confirmed numerically.

  2. Development of fission Mo-99 production technology

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Ho; Choung, W. M.; Lee, K. I. and others

    2001-05-01

    This R and D project is planed to supply domestic demands of Mo-99 through fission route, and consequently this project will be expected to rise up utilization of HANARO and KAERI's capability for marketing extension into domestic and oversea radiopharmaceutical market. HEU and LEU target types are decided and designed for fission Mo-99 production in domestic. Experimental study of target fabrication technology was performed and developed processing equipments. And conceptual design of target loading/unloading in/from HANARO device are performed. Tracer test of Mo-99 separation and purification process was performed, test results reach to Mo-99 recovery yield above 80% and decontamination factor above 1600. Combined Mo-99 separation and purification process was decided for hot test scheduled from next year, and performance test was performed. Conceptual design for modification of existing hot cell for fission Mo-99 production facility was performed and will be used for detail design. Assumption for the comparison of LEU and HEU target in fission Mo-99 production process were suggested and compared of merits and demerits in view of fabrication technology and economy feasibility.

  3. Actinide and fission product partitioning and transmutation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-07-01

    The third international information exchange meeting on actinide and fission product partitioning and transmutation, took place in Cadarache France, on 12-14 December 1994. The proceedings are presented in six sessions : an introduction session, the major programmes and international cooperation, the systems studies, the reactors fuels and targets, the chemistry and a last discussions session. (A.L.B.)

  4. UBA domain containing proteins in fission yeast

    DEFF Research Database (Denmark)

    Hartmann-Petersen, Rasmus; Semple, Colin A M; Ponting, Chris P;

    2003-01-01

    characterised on both the functional and structural levels. One example of a widespread ubiquitin binding module is the ubiquitin associated (UBA) domain. Here, we discuss the approximately 15 UBA domain containing proteins encoded in the relatively small genome of the fission yeast Schizosaccharomyces pombe...

  5. After Apollo: Fission Origin of the Moon

    Science.gov (United States)

    O'Keefe, John A.

    1973-01-01

    Presents current ideas about the fission process of the Moon, including loss of mass. Saturnian rings, center of the Moon, binary stars, and uniformitarianism. Indicates that planetary formation may be best explained as a destructive, rather than a constructive process. (CC)

  6. Formation of asteroid pairs by rotational fission.

    Science.gov (United States)

    Pravec, P; Vokrouhlický, D; Polishook, D; Scheeres, D J; Harris, A W; Galád, A; Vaduvescu, O; Pozo, F; Barr, A; Longa, P; Vachier, F; Colas, F; Pray, D P; Pollock, J; Reichart, D; Ivarsen, K; Haislip, J; Lacluyze, A; Kusnirák, P; Henych, T; Marchis, F; Macomber, B; Jacobson, S A; Krugly, Yu N; Sergeev, A V; Leroy, A

    2010-08-26

    Pairs of asteroids sharing similar heliocentric orbits, but not bound together, were found recently. Backward integrations of their orbits indicated that they separated gently with low relative velocities, but did not provide additional insight into their formation mechanism. A previously hypothesized rotational fission process may explain their formation-critical predictions are that the mass ratios are less than about 0.2 and, as the mass ratio approaches this upper limit, the spin period of the larger body becomes long. Here we report photometric observations of a sample of asteroid pairs, revealing that the primaries of pairs with mass ratios much less than 0.2 rotate rapidly, near their critical fission frequency. As the mass ratio approaches 0.2, the primary period grows long. This occurs as the total energy of the system approaches zero, requiring the asteroid pair to extract an increasing fraction of energy from the primary's spin in order to escape. We do not find asteroid pairs with mass ratios larger than 0.2. Rotationally fissioned systems beyond this limit have insufficient energy to disrupt. We conclude that asteroid pairs are formed by the rotational fission of a parent asteroid into a proto-binary system, which subsequently disrupts under its own internal system dynamics soon after formation.

  7. Brownian shape motion: Fission fragment mass distributions

    Directory of Open Access Journals (Sweden)

    Sierk Arnold J.

    2012-02-01

    Full Text Available It was recently shown that remarkably accurate fission-fragment mass distributions can be obtained by treating the nuclear shape evolution as a Brownian walk on previously calculated five-dimensional potential-energy surfaces; the current status of this novel method is described here.

  8. Energy-loss distributions of fission fragments

    Energy Technology Data Exchange (ETDEWEB)

    Demidovich, N.N.; Nakhutin, I.E.; Shatunov, V.G.

    1976-03-05

    The f-f coincidence method was used to investigate the change in the form of the energy-loss distributions of Cf/sup 252/ fission fragments in air, down to fragment energies approx.0.8 MeV. A theoretical model is considered for the estimate of the mean-squared deviations of the fragment energy-loss distributions. (AIP)

  9. Liquid uranium alloy-helium fission reactor

    Science.gov (United States)

    Minkov, V.

    1984-06-13

    This invention describes a nuclear fission reactor which has a core vessel and at least one tandem heat exchanger vessel coupled therewith across upper and lower passages to define a closed flow loop. Nuclear fuel such as a uranium alloy in its liquid phase fills these vessels and flow passages. Solid control elements in the reactor core vessel are adapted to be adjusted relative to one another to control fission reaction of the liquid fuel therein. Moderator elements in the other vessel and flow passages preclude fission reaction therein. An inert gas such as helium is bubbled upwardly through the heat exchanger vessel operable to move the liquid fuel upwardly therein and unidirectionally around the closed loop and downwardly through the core vessel. This helium gas is further directed to heat conversion means outside of the reactor vessels to utilize the heat from the fission reaction to generate useful output. The nuclear fuel operates in the 1200 to 1800/sup 0/C range, and even higher to 2500/sup 0/C.

  10. Fission neutron output measurements at LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Ronald Owen [Los Alamos National Laboratory; Haight, Robert C [Los Alamos National Laboratory; Devlin, Matthew J [Los Alamos National Laboratory; Fotiadis, Nikolaos [Los Alamos National Laboratory; Laptev, Alexander [Los Alamos National Laboratory; O' Donnell, John M [Los Alamos National Laboratory; Taddeucci, Terry N [Los Alamos National Laboratory; Tovesson, Fredrik [Los Alamos National Laboratory; Ullmann, J L [Los Alamos National Laboratory; Wender, Stephen A [Los Alamos National Laboratory; Bredeweg, T A [Los Alamos National Laboratory; Jandel, M [Los Alamos National Laboratory; Vieira, D J [Los Alamos National Laboratory; Wu, Ching - Yen [LLNL; Becker, J A [LLNL; Stoyer, M A [LLNL; Henderson, R [LLNL; Sutton, M [LLNL; Belier, Gilbert [BRUYERES-LE-CHATEL, FRANCE; Chatillon, A [BRUYERES-LE-CHATEL, FRANCE; Granier, Thierry [CEA, BRUYERES-LE-CHATEL, FRANCE; Laurent, Benoit [CEA, BRUYERES-LE-CHATEL, FRANCE; Taieb, Julien [CEA, BRUYERES-LE-CHATEL, FRANCE

    2010-01-01

    Accurate data for both physical properties and fission properties of materials are necessary to properly model dynamic fissioning systems. To address the need for accurate data on fission neutron energy spectra, especially at outgoing neutron energies below about 200 keV and at energies above 8 MeV, ongoing work at LANSCE involving collaborators from LANL, LLNL and CEA Bruyeres-le-Chatel is extending the energy range, efficiency and accuracy beyond previous measurements. Initial work in the outgoing neutron energy range from 1 to 7 MeV is consistent with current evaluations and provides a foundation for extended measurements. As part of these efforts, a new fission fragment detector that reduces backgrounds and improves timing has been designed fabricated and tested, and new neutron detectors are being assessed for optimal characteristics. Simulations of experimental designs are in progress to ensure that accuracy goals are met. Results of these measurements will be incorporated into evaluations and data libraries as they become available.

  11. Experimental effects of pressure and fluorine on apatite saturation in mafic magmas, with reference to layered intrusions and massif anorthosites

    Science.gov (United States)

    Tollari, N.; Baker, D. R.; Barnes, S.-J.

    2008-08-01

    Apatite is a cumulate phase in the upper parts of some mafic layered intrusions and anorthositic complexes. We investigated the effect of pressure and fluorine on apatite saturation in mafic magmas to better understand under which conditions this mineral crystallizes. Apatite saturation gives information about the formation of silicate rocks, and is of interest in explaining the formation of apatite-oxide-rich rocks (e.g. nelsonites comprising approximately, one-third apatite and two-third Fe-Ti oxide). Two models of formation are proposed for this rock type: crystal fractionation followed by accumulation of apatite and Fe-Ti oxides and liquid immiscibility. New experiments carried out with mafic compositions at 500 MPa confirm that the most important variables on phosphate saturation are SiO2 and CaO. Fluorine addition leads to apatite saturation at lower SiO2 and higher CaO concentrations. Comparison of our results with those of previous experimental studies on liquid-liquid immiscibility at upper-to-mid-crustal conditions allows us to investigate the relative importance of apatite saturation versus liquid-liquid immiscibility in the petrogenesis of nelsonites and similar rocks. The liquid line of descent of three natural examples studied (the Sept-Îles intrusive suite, the anorthositic Complex of the Lac-St-Jean and the Skaergaard layered intrusion) do not cross the liquid-liquid immiscibility field before they reach apatite saturation. Thus, the apatite-oxide-rich rock associated with these three intrusive suites are best explained by crystal fractionation followed by accumulation of apatite and Fe-Ti oxides.

  12. Neutron induced fission of 234U

    Directory of Open Access Journals (Sweden)

    Pomp S.

    2012-02-01

    Full Text Available The fission fragment properties of 234U(n,f were investigated as a function of incident neutron energy from 0.2 MeV up to 5 MeV. The fission fragment mass, angular distribution and kinetic energy were measured with a double Frisch-grid ionization chamber using both analogue and digital data acquisition techniques. The reaction 234U(n,f is relevant, since it involves the same compound nucleus as formed after neutron evaporation from highly excited 236U*, the so-called second-chance fission of 235U. Experimental data on fission fragment properties like fission fragment mass and total kinetic energy (TKE as a function of incident neutron energy are rather scarce for this reaction. For the theoretical modelling of the reaction cross sections for Uranium isotopes this information is a crucial input parameter. In addition, 234U is also an important isotope in the Thorium-based fuel cycle. The strong anisotropy of the angular distribution around the vibrational resonance at En = 0.77 MeV could be confirmed using the full angular range. Fluctuations in the fragment TKE have been observed in the threshold region around the strong vibrational resonance at En = 0.77 MeV. The present results are in contradiction with corresponding literature values. Changes in the mass yield around the vibrational resonance and at En = 5 MeV relative to En = 2 MeV show a different signature. The drop in mean TKE around 2.5 to 3 MeV points to pair breaking as also observed in 235,238U(n,f. The measured two-dimensional mass yield and TKE distribution have been described in terms of fission modes. The yield of the standard 1 (S1 mode shows fluctuations in the threshold of the fission cross section due to the influence of the resonance and levels off at about 20% yield for higher incident neutron energies. The S2 mode shows the respective opposite behaviour. The mean TKE of both modes decreases with En. The decrease in mean TKE overrules the increase in S1 yield, so the mean

  13. The partial fission of fast spinning asteroids

    Science.gov (United States)

    Tardivel, Simon; Sanchez, Paul; Scheeres, Daniel J.

    2016-10-01

    The spin rates of asteroids systematically change over time due the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. Above a certain spin rate that depends on the body's density, regions of an asteroid can enter in tension, with components held to the body by cohesive forces. When the body fails, deformation or fission can occur. Catastrophic fission leading to complete disruption has been directly observed in active asteroid P/2013 R3. Partial fission, the loss of only part of the body, has been proposed as a mechanism for the formation of binaries and is explored here.The equatorial cavities of (341843) 2008 EV5 and of (185851) 2000 DP107 (a binary system) are consistent with a localized partial fission of the body (LPSC 2016 #1036). The examination of the gravity field of these bodies reveals that a mass placed within these cavities could be shed. In this mechanism, the outward pull of inertial forces creates an average stress at the cavity interface of ≈1 Pa for 2008 EV5 and ≈3 Pa for 2000 DP107 at spin periods of ≈3.15 h for the assumed densities of 1.3 g/cm3.This work continues the study of this partial, localized fission. Specifically, it addresses the issue of the low cohesion necessary to the mechanism. These cohesion values are typically lower than global strength values inferred on other asteroids (10 - 200 Pa), meaning that partial fission may occur prior to larger-scale deformations. Yet, several processes can explain the discrepancy, as they can naturally segregate particles by size. For instance, landslides or granular convection (Brazil nut effect) could bring larger boulders to the equator of the body, while finer particles are left at higher latitudes or sink to the center. Conversely, failure of the interior could bring boulders to the surface. The peculiar profile shape of these asteroids, shared by many binaries (e.g. 1999 KW4, 1996 FG3) may also be a clue of this heterogeneity, as this "spin top" shape is obtained in simulations with

  14. Microscopic theory of nuclear fission: a review

    Science.gov (United States)

    Schunck, N.; Robledo, L. M.

    2016-11-01

    This article reviews how nuclear fission is described within nuclear density functional theory. A distinction should be made between spontaneous fission, where half-lives are the main observables and quantum tunnelling the essential concept, and induced fission, where the focus is on fragment properties and explicitly time-dependent approaches are often invoked. Overall, the cornerstone of the density functional theory approach to fission is the energy density functional formalism. The basic tenets of this method, including some well-known tools such as the Hartree-Fock-Bogoliubov (HFB) theory, effective two-body nuclear potentials such as the Skyrme and Gogny force, finite-temperature extensions and beyond mean-field corrections, are presented succinctly. The energy density functional approach is often combined with the hypothesis that the time-scale of the large amplitude collective motion driving the system to fission is slow compared to typical time-scales of nucleons inside the nucleus. In practice, this hypothesis of adiabaticity is implemented by introducing (a few) collective variables and mapping out the many-body Schrödinger equation into a collective Schrödinger-like equation for the nuclear wave-packet. The region of the collective space where the system transitions from one nucleus to two (or more) fragments defines what are called the scission configurations. The inertia tensor that enters the kinetic energy term of the collective Schrödinger-like equation is one of the most essential ingredients of the theory, since it includes the response of the system to small changes in the collective variables. For this reason, the two main approximations used to compute this inertia tensor, the adiabatic time-dependent HFB and the generator coordinate method, are presented in detail, both in their general formulation and in their most common approximations. The collective inertia tensor enters also the Wentzel-Kramers-Brillouin (WKB) formula used to extract

  15. Specific fission J-window and angular momentum dependence of the fission barrier

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Hiroshi; Saito, Tadashi; Takahashi, Naruto; Yokoyama, Akihiko [Osaka Univ., Suita (Japan); Shinohara, Atsushi

    1997-04-01

    A method to determine a unique J-window in the fission process was devised and the fissioning nuclide associated with thus extracted J-window was identified for each of the heavy-ion reaction systems. Obtained fission barriers at the resulting J-window were compared with the calculated values by the rotating finite range model (RFRM). The deduced barriers for individual nuclides were compared with the RFRM barriers to reproduce more or less the angular momentum dependence the RFRM prediction. The deduced systematic behavior of the fission barrier indicates no even-odd and shell corrections are necessary. The nuclear dissipation effect based on Kramer`s model revealed substantial reduction of the statistically deduced barrier heights and brought a fairly large scattering from the RFRM J-dependence. However, introduction of the temperature-dependent friction coefficient ({gamma} = 2 for T {>=} 1.0 MeV and 0.5 for T < 1.0 MeV) was found to bring about satisfactory agreement with both RFRM fission barriers and the pre-fission neutron multiplicity systematics. (author). 81 refs.

  16. The Oklo natural reactor: Cumulative fission yields and retentivity of the symmetric mass region fission products

    Science.gov (United States)

    De Laeter, J. R.; Rosman, K. J. R.; Smith, C. L.

    1980-10-01

    Solid source mass spectrometry has been used to determine the relative cumulative fission yields of five elements in three samples of uranium ore from reactor zones in the Oklo mine site. Eighteen fission chains covering the mass range from 105 ≤ A ≤ 130 have been measured for Pd, Ag, Cd, Sn and Te. These measurements have enabled a number of nuclear parameters to be calculated including the relative proportions of 235U, 238U and 239Pu involved in the fission process. The concentration of the five elements in the Oklo samples have also been measured using the stable isotope dilution technique. These values have then been compared to the estimates of the amount of these elements produced by fission under the conditions that are appropriate to the three samples. This procedure enables the retentivity of the elements in the reactor zones to be evaluated. Our work confirms the fact that Pd and Te are retained almost in their entirety in the samples, whereas the other three elements have been partially lost from the reactor site. Almost all the Cd fission products have been lost, and more than 50% of the Ag and Sn fission-produced material has been removed.

  17. Evolution of isotopic fission-fragment yields with excitation energy

    Directory of Open Access Journals (Sweden)

    Bazin D.

    2012-07-01

    Full Text Available Two fission experiments have been performed at GANIL using 238U beams at different energies and light targets. Different fissioning systems were produced with excitation energies from 10 to 230 MeV and their decay by fission was investigated with GANIL spectrometers. Preliminary fission-fragment isotopic distributions have been obtained. The evolution with impinging energy of their properties, the neutron excess and the width of the neutron-number distributions, gives important insights into the dynamics of fusion-fission mechanism.

  18. Application of the dinuclear system model to fission process

    Directory of Open Access Journals (Sweden)

    Andreev A. V.

    2016-01-01

    Full Text Available A theoretical evaluation of the collective excitation spectra of nucleus at large deformations is possible within the framework of the dinuclear system model, which treats the wave function of the fissioning nucleus as a superposition of a mononucleus configuration and two-cluster configurations in a dynamical way, permitting exchange of nucleons between clusters. In this work the method of calculation of the potential energy and the collective spectrum of fissioning nucleus at scission point is presented. Combining the DNS model calculations and the statistical model of fission we calculate the mass, total kinetic energy, and angular distribution of fission fragments for the neutron–induced fission of 239Pu.

  19. Apatite in carbonatitic rocks: Compositional variation, zoning, element partitioning and petrogenetic significance

    Science.gov (United States)

    Chakhmouradian, Anton R.; Reguir, Ekaterina P.; Zaitsev, Anatoly N.; Couëslan, Christopher; Xu, Cheng; Kynický, Jindřich; Mumin, A. Hamid; Yang, Panseok

    2017-03-01

    Apatite-group phosphates are nearly ubiquitous in carbonatites, but our understanding of these minerals is inadequate, particularly in the areas of element partitioning and petrogenetic interpretation of their compositional variation among spatially associated rocks and within individual crystals. In the present work, the mode of occurrence, and major- and trace-element chemistry of apatite (sensu lato) from calcite and dolomite carbonatites, their associated cumulate rocks (including phoscorites) and hydrothermal parageneses were studied using a set of 80 samples from 50 localities worldwide. The majority of this set represents material for which no analytical data are available in the literature. Electron-microprobe and laser-ablation mass-spectrometry data ( 600 and 400 analyses, respectively), accompanied by back-scattered-electron and cathodoluminescence images and Raman spectra, were used to identify the key compositional characteristics and zoning patterns of carbonatitic apatite. These data are placed in the context of phosphorus geochemistry in carbonatitic systems and carbonatite evolution, and compared to the models proposed by previous workers. The documented variations in apatite morphology and zoning represent a detailed record of a wide range of evolutionary processes, both magmatic and fluid-driven. The majority of igneous apatite from the examined rocks is Cl-poor fluorapatite or F-rich hydroxylapatite (≥ 0.3 apfu F) with 0.2-2.7 wt.% SrO, 0-4.5 wt.% LREE2O3, 0-0.8 wt.% Na2O, and low levels of other cations accommodated in the Ca site (up to 1000 ppm Mn, 2300 ppm Fe, 200 ppm Ba, 150 ppm Pb, 700 ppm Th and 150 ppm U), none of which show meaningful correlation with the host-rock type. Silicate, (SO4)2 - and (VO4)3 - anions, substituting for (PO4)3 -, tend to occur in greater abundance in crystals from calcite carbonatites (up to 4.2 wt.% SiO2, 1.5 wt.% SO3 and 660 ppm V). Although (CO3)2 - groups are very likely present in some samples, Raman micro

  20. Solid state 31NMR studies of the conversion of amorphous tricalcium phosphate to apatitic tricalcium phosphate.

    Science.gov (United States)

    Roberts, J E; Heughebaert, M; Heughebaert, J C; Bonar, L C; Glimcher, M J; Griffin, R G

    1991-12-01

    The hydrolytic conversion of a solid amorphous calcium phosphate of empirical formula Ca9 (PO4)6 to a poorly crystalline apatitic phase, under conditions where Ca2+ and PO4(3-) were conserved, was studied by means of solid-state magic-angle sample spinning 31P-NMR (nuclear magnetic resonance). Results showed a gradual decrease in hydrated amorphous calcium phosphate and the formation of two new PO4(3-)-containing components: an apatitic component similar to poorly crystalline hydroxyapatite and a protonated PO4(3-), probably HPO4(2-) in a dicalcium phosphate dihydrate (DCPD) brushite-like configuration. This latter component resembles the brushite-like HPO4(2-) component previously observed by 31P-NMR in apatitic calcium phosphates of biological origin. Results were consistent with previous studies by Heughebaert and Montel [18] of the kinetics of the conversion of amorphous calcium phosphate to hydroxyapatite under the same conditions.

  1. Échange terres rares légères Ca dans l'apatite

    Science.gov (United States)

    Iqdari, Abderrahmane; Velde, Bruce; Benalioulhaj, Noureddine; Dujon, Saint-Clair; El Yamine, Nacer

    2003-04-01

    Diffusion experiments were carried out on natural apatite crystals that were immersed in molten light rare earth element (REE) chloride salt at temperatures between 900 and 1150 °C for periods up to 35 days. Electron microprobe analysis of the crystals showed that light REEs replaced Ca according to electronic balance, i.e. 2 REE3+ for 3 Ca2+. These diffusion profiles indicate that a maximum amount of substitution in the structure occurs when two of the ten Ca ions in apatite are replaced by the REE diffusing elements. Anisotropic diffusion is observed between a and c crystallographic directions. Comparison of maximum distance indicates that the larger ions move more easily in the apatite structure. We conclude that the light REEs diffuse within the channel structures of the mineral, and that this diffusion is controlled by the substitution type of elements in the calcium sites. To cite this article: A. Iqdari et al., C. R. Geoscience 335 (2003).

  2. PNNL Apatite Investigation at 100-NR-2 Quality Assurance Project Plan

    Energy Technology Data Exchange (ETDEWEB)

    Fix, N. J.

    2009-04-02

    In 2004, the U.S. Department of Energy, Fluor Hanford, Inc., Pacific Northwest National Laboratory (PNNL), and the Washington Department of Ecology agreed that the long-term strategy for groundwater remediation at the 100-N Area would include apatite sequestration as the primary treatment, followed by a secondary treatment if necessary. Since then, the agencies have worked together to agree on which apatite sequestration technology has the greatest chance of reducing strontium-90 flux to the Columbia River. This Quality Assurance Project Plan provides the quality assurance requirements and processes that will be followed by staff working on the PNNL Apatite Investigation at 100-NR-2 Project. The plan is designed to be used exclusively by project staff.

  3. Carbon isotopes in eclogite and apatite separate from Huangzhen and Shima in SE Dabie

    Institute of Scientific and Technical Information of China (English)

    李一良; 郑永飞; 龚冰; 傅斌

    2000-01-01

    The carbon isotope compositions of high- and ultrahigh-pressure eclogite and apatite separate from Huangzhen and Shima in SE Dabie Mountains were analyzed by EA-MS online technique. The δ13C values of the eclogites cover a wide range of -30.7‰ - +1.5‰, whereasthose of apatites only have a small range of -28.1‰- -21.0‰. Some of the eclogites with thehigh δ13C values suffered retrogressive alteration by CO2-bearing fluids. The low δ13C values of the apatites indicate that the eclogites contain surficial carbon of organic origin. It is concluded that protoliths of the eclogites were exposed to the surface of the Earth, and that the carbon-bearing fluid was depleted in 13C during the eclogite-facies metamorphism.

  4. Carbon isotopes in eclogite and apatite separate from Huangzhen and Shima in SE Dabie

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The carbon isotope compositions of high- and ultrahigh-pressure eclogite and apatite separate from Huangzhen and Shima in SE Dabie Mountains were analyzed by EA-MS online technique. The δ13C values of the eclogites cover a wide range of -30.7‰ - +1.5‰, whereas those of apatites only have a small range of -28.1‰--21.0‰. Some of the eclogites with the high δ13C values suffered retrogressive alteration by CO2-bearing fluids. The low δ13C values of the apatites indicate that the eclogites contain surficial carbon of organic origin. It is concluded that protoliths of the eclogites were exposed to the surface of the Earth, and that the carbon-bearing fluid was depleted in 13C during the eclogite-facies metamorphism.

  5. Fifty years of nuclear fission: Nuclear data and measurements series

    Energy Technology Data Exchange (ETDEWEB)

    Lynn, J.E.

    1989-06-01

    This report is the written version of a colloquium first presented at Argonne National Laboratory in January 1989. The paper begins with an historical preamble about the events leading to the discovery of nuclear fission. This leads naturally to an account of early results and understanding of the fission phenomena. Some of the key concepts in the development of fission theory are then discussed. The main theme of this discussion is the topography of the fission barrier, in which the interplay of the liquid-drop model and nucleon shell effects lead to a wide range of fascinating phenomena encompassing metastable isomers, intermediate-structure effects in fission cross-sections, and large changes in fission product properties. It is shown how study of these changing effects and theoretical calculations of the potential energy of the deformed nucleus have led to broad qualitative understanding of the nature of the fission process. 54 refs., 35 figs.

  6. Tracking Porters

    DEFF Research Database (Denmark)

    Bruun, Maja Hojer; Krause-Jensen, Jakob; Nielsen, Margit Saltofte

    2015-01-01

    Anthropology attempts to gain insight into people's experiential life-worlds through long-term fieldwork. The quality of anthropological knowledge production, however, does not depend solely on the duration of the stay in the field, but also on a particular way of seeing social situations. The an...... the students followed the work of a group of porters. Drawing on anthropological concepts and research strategies the students gained crucial insights about the potential effects of using tracking technologies in the hospital....

  7. The study of geochemical behavior of rare earth elements in apatites from the Hormoz Island, Persian Gulf

    Directory of Open Access Journals (Sweden)

    Ali Rostami

    2014-04-01

    Full Text Available The study area is located about 3 km southwest of the Hormoz Island in the Hormozgan province, in the Persian Gulf. The main rock units in the region consist of a highly altered acidic pluton cratophyre, which is responsible for apatite formation, diabasic dike, marl and altered basalt. Apatite is the only phosphate mineral in the Hormoz Island, which has accumulated REE in its crystal structure. The amount of Na2O and SiO2 oxides in apatite are high and the average content of the main elements Fe, Mg, Al, Ca are 7.5 ppm, 365 ppm, 2880 ppm and 27.8%, respectively. The Y, Mn, Rb contents increase and Sr decreases with increasing magmatic differentiation. It shows that a moderate magmatic differentiation occurred during the crystallization of apatite. The total REE content in the Hormoz apatite is high (1.22-2.25%. LREE/HREE ratio is also high. This means that Hormoz apatites are enriched in light rare earth elements. The REE normalized pattern shows a negative slope with a negative Eu anomaly. According to various diagrams based on apatite composition, it is deduced that the Hormoz apatites belong to mafic I-type granitoids with high oxidation state (Fe2O3/FeO>1.

  8. Theoretical stability assessment of uranyl phosphates and apatites: Selection of amendments for in situ remediation of uranium

    Energy Technology Data Exchange (ETDEWEB)

    Raicevic, S. [Institute of Nuclear Sciences VINCA, Radiation and Environmental Protection Laboratory, P.O.Box 522, 11001 Belgrade (Serbia and Montenegro)]. E-mail: raich@beotel.yu; Wright, J.V. [PIMS NW, Inc., 201 North Edison, Suite 226, Richland, WA 99336 (United States); Veljkovic, V. [Institute of Nuclear Sciences VINCA, Center for Multidisciplinary Research and Engineering, P.O.Box 522, 11001 Belgrade (Serbia and Montenegro); Conca, J.L. [Los Alamos National Laboratory, 115 North Main Street, Carlsbad, NM 88220 (United States)

    2006-02-15

    Addition of an amendment or reagent to soil/sediment is a technique that can decrease mobility and reduce bioavailability of uranium (U) and other heavy metals in the contaminated site. According to data from literature and results obtained in field studies, the general mineral class of apatites was selected as a most promising amendment for in situ immobilization/remediation of U. In this work we presented theoretical assessment of stability of U(VI) in four apatite systems (hydroxyapatite (HAP), North Carolina Apatite (NCA), Lisina Apatite (LA), and Apatite II) in order to determine an optimal apatite soil amendment which could be used for in situ remediation of uranium. In this analysis we used a theoretical criterion which is based on calculation of the ion-ion interaction potential, representing the main term of the cohesive energy of the matrix/pollutant system. The presented results of this analysis indicate (i) that the mechanism of immobilization of U by natural apatites depends on their chemical composition and (ii) that all analyzed apatites represent, from the point of view of stability, promising materials which could be used in field remediation of U-contaminated sites.

  9. Theoretical stability assessment of uranyl phosphates and apatites: selection of amendments for in situ remediation of uranium.

    Science.gov (United States)

    Raicevic, S; Wright, J V; Veljkovic, V; Conca, J L

    2006-02-15

    Addition of an amendment or reagent to soil/sediment is a technique that can decrease mobility and reduce bioavailability of uranium (U) and other heavy metals in the contaminated site. According to data from literature and results obtained in field studies, the general mineral class of apatites was selected as a most promising amendment for in situ immobilization/remediation of U. In this work we presented theoretical assessment of stability of U(VI) in four apatite systems (hydroxyapatite (HAP), North Carolina Apatite (NCA), Lisina Apatite (LA), and Apatite II) in order to determine an optimal apatite soil amendment which could be used for in situ remediation of uranium. In this analysis we used a theoretical criterion which is based on calculation of the ion-ion interaction potential, representing the main term of the cohesive energy of the matrix/pollutant system. The presented results of this analysis indicate (i) that the mechanism of immobilization of U by natural apatites depends on their chemical composition and (ii) that all analyzed apatites represent, from the point of view of stability, promising materials which could be used in field remediation of U-contaminated sites.

  10. A new glance at ruthenium sorption mechanism on hydroxy, carbonate, and fluor apatites: Analytical and structural studies.

    Science.gov (United States)

    Tõnsuaadu, K; Gruselle, M; Villain, F; Thouvenot, R; Peld, M; Mikli, V; Traksmaa, R; Gredin, P; Carrier, X; Salles, L

    2006-12-15

    The sorption mechanism of Ru3+ ions on hydroxy (HAp), carbonate (CO3HAp), and fluor apatites (FAp) has been studied in detail. Ru apatites were obtained by reaction of the apatites with RuCl3 in aqueous solution. The structure and composition of the ruthenium-modified apatites were studied by several techniques: elemental analysis, XRD, EXAFS, IR, NMR, SEM-EDS, TEM, and thermal analysis. The amount of Ru in the modified apatite varies from 7.8 to 10.5 wt% and is not related to the initial composition or the specific surface area of the apatite. The different characterization techniques show that in the Ru-modified apatites Ru is surrounded by six oxygen atoms and do not contain any chlorine. For Ru-HAp and Ru-CO3HAp the new phase is amorphous whereas it is crystalline for FAp. The catalytic oxidation ability is higher for Ru-HAp and Ru-CO3HAp compared to Ru-FAp apatite in the oxidation of benzylic alcohol.

  11. Pacific Northwest National Laboratory Apatite Investigation at the 100-NR-2 Quality Assurance Project Plan

    Energy Technology Data Exchange (ETDEWEB)

    Fix, N. J.

    2008-03-28

    This Quality Assurance Project Plan provides the quality assurance requirements and processes that will be followed by staff working on the 100-NR-2 Apatite Project. The U.S. Department of Energy, Fluor Hanford, Inc., Pacific Northwest National Laboratory, and the Washington Department of Ecology agreed that the long-term strategy for groundwater remediation at 100-N would include apatite sequestration as the primary treatment, followed by a secondary treatment. The scope of this project covers the technical support needed before, during, and after treatment of the targeted subsurface environment using a new high-concentration formulation.

  12. Growth of apatite on chitosan-multiwall carbon nanotube composite membranes

    Science.gov (United States)

    Yang, Jun; Yao, Zhiwen; Tang, Changyu; Darvell, B. W.; Zhang, Hualin; Pan, Lingzhan; Liu, Jingsong; Chen, Zhiqing

    2009-07-01

    Bioactive membranes for guided tissue regeneration would be of value for periodontal therapy. Chitosan-multiwall carbon nanotube (CS-MWNT) composites were treated to deposit nanoscopic apatite for MWNT proportions of 0-4 mass%. Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction were used for characterization. Apatite was formed on the CS-MWNT composites at low MWNT concentrations, but the dispersion of the MWNT affects the crystallite size and the Ca/P molar ratio of the composite. The smallest crystallite size was 9 nm at 1 mass% MWNT.

  13. Growth of apatite on chitosan-multiwall carbon nanotube composite membranes

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jun; Yao Zhiwen [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China); Tang Changyu [Department of Polymer Science and Materials, Sichuan University (China); Darvell, B.W. [Dental Materials Science, Faculty of Dentistry, University of Hong Kong (Hong Kong); Zhang Hualin; Pan Lingzhan; Liu Jingsong [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China); Chen Zhiqing, E-mail: yangj0710@gmail.com [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China)

    2009-07-30

    Bioactive membranes for guided tissue regeneration would be of value for periodontal therapy. Chitosan-multiwall carbon nanotube (CS-MWNT) composites were treated to deposit nanoscopic apatite for MWNT proportions of 0-4 mass%. Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction were used for characterization. Apatite was formed on the CS-MWNT composites at low MWNT concentrations, but the dispersion of the MWNT affects the crystallite size and the Ca/P molar ratio of the composite. The smallest crystallite size was 9 nm at 1 mass% MWNT.

  14. Fisson-track constrains on superposed folding in the Beishan orogenic belt, southernmost Altaids

    Directory of Open Access Journals (Sweden)

    Zhonghua Tian

    2016-03-01

    Full Text Available The Hongyanjing inter-arc basin, is located at the central part of Beishan Orogenic College (BOC, Gansu Province, northwest China. Thick sequences of Permian sediments were strongly folded, forming extremely spectacular superposed folds. To better understand the thermal history of Hongyanjing inter-arc basin and to potentially constrain the timing of deformation, apatite fission track thermochronology method was applied on two superposed folds in the Hongyanjing Basin. Samples from the basin, yield central AFT ages ranging from ∼206 to 118 Ma. AFT peak ages were largely consistent between samples and can divided into three groups: 245, 204–170 and 112–131 Ma. Subsequent thermal history modeling of the samples from the Hongyanjing Basin can be summarized as follows: (1 thermal reheating by sedimentary burial at ∼ 260 to ∼220 Ma; (2 major cooling from ∼220 to ∼180 Ma; (3 an episode of very slow subsequent cooling from ∼180 to 65 Ma (∼80 °C to present-day outcrop temperatures. Sediments in the Hongyanjing Basin were folded forming F1 fold during the early to late Triassic (∼240–∼220 Ma, by regional stress, and at the time that the adjacent Xingxingxia shear zone started to become active. It is further suggested that the F2 folding occurred at ∼225–219 Ma. The deformation age of F2 should be extended to 180 Ma based on our thermal history modeling for the Hongyanjing Basin, which show a rapid exhumation and cooling at the late Triassic to early Jurassic (∼220–∼180 Ma. In our interpretations, the F1 folding is therefore thought to be related to the final closure of the Paleo-Asian Ocean, while the F2 folding occurred at ∼225–180 Ma associated with a major pulse of orogenesis in the BOC.

  15. Sub-library of Updated Fission Barrier Parameters(CENPL-FBP2)

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The fission barrier parameters are important to determine the fission character of a nucleus. The fission barrier parameters and fission level densities are key ingredients in calculations of not only fission cross section but also various cross sections, and spectra for the fissile nuclides, even heavy nuclides at higher incident energies. It is necessaries that the accuracy of fission barrier parameters requires even higher, and nuclides with fission barrier parameters can cover even wider nuclear range.

  16. Axisymmetric Magnetic Mirror Fusion-Fission Hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Moir, R. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Martovetsky, N. N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Molvik, A. W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Ryutov, D. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simonen, T. C. [Univ. of California, Berkeley, CA (United States)

    2011-05-13

    The achieved performance of the gas dynamic trap version of magnetic mirrors and today’s technology we believe are sufficient with modest further efforts for a neutron source for material testing (Q=Pfusion/Pinput~0.1). The performance needed for commercial power production requires considerable further advances to achieve the necessary high Q>>10. An early application of the mirror, requiring intermediate performance and intermediate values of Q~1 are the hybrid applications. The Axisymmetric Mirror has a number of attractive features as a driver for a fusion-fission hybrid system: geometrical simplicity, inherently steady-state operation, and the presence of the natural divertors in the form of end tanks. This level of physics performance has the virtue of low risk and only modest R&D needed and its simplicity promises economy advantages. Operation at Q~1 allows for relatively low electron temperatures, in the range of 4 keV, for the DT injection energy ~ 80 keV. A simple mirror with the plasma diameter of 1 m and mirror-to-mirror length of 35 m is discussed. Simple circular superconducting coils are based on today’s technology. The positive ion neutral beams are similar to existing units but designed for steady state. A brief qualitative discussion of three groups of physics issues is presented: axial heat loss, MHD stability in the axisymmetric geometry, microstability of sloshing ions. Burning fission reactor wastes by fissioning actinides (transuranics: Pu, Np, Am, Cm, .. or just minor actinides: Np, Am, Cm, …) in the hybrid will multiply fusion’s energy by a factor of ~10 or more and diminish the Q needed to less than 1 to overcome the cost of recirculating power for good economics. The economic value of destroying actinides by fissioning is rather low based on either the cost of long-term storage or even deep geologic disposal so most of the revenues of hybrids will come from electrical power. Hybrids that obtain revenues from

  17. Effects of apatite particle size in two apatite/collagen composites on the osteogenic differentiation profile of osteoblastic cells.

    Science.gov (United States)

    Hatakeyama, Wataru; Taira, Masayuki; Chosa, Naoyuki; Kihara, Hidemichi; Ishisaki, Akira; Kondo, Hisatomo

    2013-12-01

    The development of new osteoconductive bone substitute materials is expected in medicine. In this study, we attempted to produce new hydroxylapatite (HAP)/collagen (Col) composites using two HAP particles of different sizes and porcine type I collagen. The two HAP particles were either nano-sized (40 nm in average diameter; n-HAP) or had macro-pore sizes of 0.5‑1.0 mm in length with fully interconnected pores (m-HAP). The aim of this study was to investigate the effects of apatite particle size in two HAP/Col composites on the osteogenic differentiation profile in osteoblast-like cells (SaOS-2). We created a collagen control sponge (Col) and two HAP/Col composite sponges (n-HAP/Col and m-HAP/Col) using freeze-drying and dehydrothermal cross-linking techniques, and then punched out samples of 6 mm in diameter and 1 mm in height. The SaOS-2 cells were cultured on three test materials for 1, 2, 3 and 4 weeks. Total RNA was extracted from the cultured cells and the expression of osteogenic differentiation-related genes was evaluated by reverse transcription PCR (RT-PCR) using primer sets of alkaline phosphatase (ALP), type 1 collagen (COL1), bone sialoprotein (BSP) and osteocalcin precursor [bone gamma-carboxyglutamate (gla) protein (BGLAP)] genes, as well as the β-actin gene. The cells were also cultured on Col, n-HAP/Col and m-HAP/Col specimens for 1 and 4 weeks, and were then observed under a scanning electron microscope (SEM). The experimental results were as follows: RT-PCR indicated that osteogenic differentiation, particularly the gene expression of BSP, was most accelerated when the cells were cultured on n-HAP/Col specimens, followed by m-HAP/Col, whilst the weakest accelaeration was observed when the cells were cultured on Col specimens. As shown by the SEM images, the SaOS-2 cells were fibroblastic when cultured on Col specimens for up to 4 weeks; they were fibroblastic when cultured on n-HAP/Col specimens for 1 week, but appeared as spheroids

  18. Fission-fusion dynamics over large distances in raven non-breeders.

    Science.gov (United States)

    Loretto, Matthias-Claudio; Schuster, Richard; Itty, Christian; Marchand, Pascal; Genero, Fulvio; Bugnyar, Thomas

    2017-03-23

    The influence of fission-fusion dynamics, i.e., temporal variation in group size and composition, on social complexity has been studied in large-brained mammals that rely on social bonds. Little is known about birds, even though some species like ravens have recently received attention for their socio-cognitive skills and use of social bonds. While raven breeders defend territories year-round, non-breeders roam through large areas and form groups at food sources or night roosts. We here examined the fission-fusion patterns of non-breeding ravens over years, investigating whether birds meet repeatedly either at the same or at different locations. We combined four large datasets: presence-absence observations from two study sites (Austria, Italy) and GPS-tracking of ravens across two study areas (Austria, France). As expected, we found a highly dynamic system in which individuals with long phases of temporary settlement had a high probability of meeting others. Although GPS-tagged ravens spread out over thousands of square kilometres, we found repeated associations between almost half of the possible combinations at different locations. Such a system makes repeated interactions between individuals at different sites possible and likely. High fission-fusion dynamics may thus not hinder but shape the social complexity of ravens and, possibly, other long-term bonded birds.

  19. Recent studies in heavy ion induced fission reactions

    Science.gov (United States)

    Choudhury, R. K.

    2001-08-01

    Nuclear fission process involves large scale shape changes of the nucleus, while it evolves from a nearly spherical configuration to two separated fission fragments. The dynamics of these shape changes in the nuclear many body system is governed by a strong interplay of the collective and single particle degrees of freedom. With the availability of heavy ion accelerators, there has been an impetus to study the nuclear dynamics through the investigations of nucleus--nucleus collisions involving fusion and fission process. From the various investigations carried out in the past years, it is now well recognized that there is large scale damping of collective modes in heavy ion induced fission reactions, which in other words implies that nuclear motion is highly viscous. In recent years, there have been many experimental observations in heavy ion induced fission reactions at medium bombarding energies, which suggest possible occurrence of various non-equilibrium modes of fission such as quasi-fission, fast fission and pre-equilibrium fission, where some of the internal degrees of freedom of the nucleus is not fully equilibrated. We have carried out extensive investigations on the fission fragment angular distributions at near barrier bombarding energies using heavy fissile targets. The measured fragment anisotropies when compared with the standard saddle point model (SSPM) calculations show that for projectile-target systems having zero or low ground state spins, the angular anisotropy exhibits a peak-like behaviour at the sub barrier energies, which cannot be explained by the SSPM calculations. For projectiles or targets with large ground state spins, the anomalous peaking gets washed out due to smearing of the K-distribution by the intrinsic entrance channel spins. Recently studies have been carried out on the spin distributions of fission fragments through the gamma ray multiplicity measurements. The fission fragments acquire spin mainly from two sources: (i) due to

  20. A new approach to prompt fission neutron TOF data treatment

    Science.gov (United States)

    Zeynalov, Sh.; Zeynalova, O. V.; Hambsch, F.-J.; Oberstedt, S.

    The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics along with associated digital signal processing algorithms. A new mathematical approach, applicable to single events, was developed for prompt fission neutron (PFN) time-offlight distribution unfolding. The main goal was to understand the reasons of the long existing discrepancy between theoretical calculations and the measurements of prompt fission neutron (PFN) emission dependence on the total kinetic energy (TKE) of the fission fragments (FF). Since the 252Cf (sf) reaction is one of the main references for nuclear data the understanding of the PFN emission mechanism is very important both for nuclear fission theory and nuclear data. The experimental data were taken with a twin Frisch-grid ionization chamber and a NE213-equivalent neutron detector in an experimental setup similar to the well known work of C. Budtz-Jorgensen and H.-H. Knitter. About 2.5 × 105 coincidences between fission fragment (FF) and neutron detector response to prompt fission neutron detection have been registered (∼ 1.6 × 107 of total recorded fission events). Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12-bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. The main goal of this work was a detailed description of the prompt fission neutron treatment.

  1. A new role for myosin II in vesicle fission.

    Science.gov (United States)

    Flores, Juan A; Balseiro-Gomez, Santiago; Cabeza, Jose M; Acosta, Jorge; Ramirez-Ponce, Pilar; Ales, Eva

    2014-01-01

    An endocytic vesicle is formed from a flat plasma membrane patch by a sequential process of invagination, bud formation and fission. The scission step requires the formation of a tubular membrane neck (the fission pore) that connects the endocytic vesicle with the plasma membrane. Progress in vesicle fission can be measured by the formation and closure of the fission pore. Live-cell imaging and sensitive biophysical measurements have provided various glimpses into the structure and behaviour of the fission pore. In the present study, the role of non-muscle myosin II (NM-2) in vesicle fission was tested by analyzing the kinetics of the fission pore with perforated-patch clamp capacitance measurements to detect single vesicle endocytosis with millisecond time resolution in peritoneal mast cells. Blebbistatin, a specific inhibitor of NM-2, dramatically increased the duration of the fission pore and also prevented closure during large endocytic events. Using the fluorescent markers FM1-43 and pHrodo Green dextran, we found that NM-2 inhibition greatly arrested vesicle fission in a late phase of the scission event when the pore reached a final diameter of ∼ 5 nm. Our results indicate that loss of the ATPase activity of myosin II drastically reduces the efficiency of membrane scission by making vesicle closure incomplete and suggest that NM-2 might be especially relevant in vesicle fission during compound endocytosis.

  2. Detection of fission fragments by secondary emission; Detection des fragments de fission par emission secondaire

    Energy Technology Data Exchange (ETDEWEB)

    Audias, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    This fission fragment detecting apparatus is based on the principle that fragments traversing a thin foil will cause emission of secondary electrons. These electrons are then accelerated (10 kV) and directly detected by means of a plastic scintillator and associated photomultiplier. Some of the advantages of such a detector are, its rapidity, its discriminating power between alpha particles and fission fragments, its small energy loss in detecting the fragments and the relatively great amount of fissionable material which it can contain. This paper is subdivided as follows: a) theoretical considerations b) constructional details of apparatus and some experimental details and c) a study of the secondary emission effect itself. (author) [French] Le detecteur de fragments de fission que nous avons realise est base sur le principe de l&apo