Uranium content of petroleum by fission track technique

International Nuclear Information System (INIS)

Paschoa, A.S.; Mafra, O.Y.; Oliveira, C.A.N. de; Pinto, L.R.

1981-03-01

The feasibility of the fission track registration technique to investigate the natural uranium concentration in petroleum is examined. The application of this technique to petroleum is briefly described and discussed critically. The results obtained so far indicate uranium concentrations in samples of Brazilian petroleum which are over the detect ion limit of fission track technique. (Author) [pt

Automatic counting of fission fragments tracks using the gas permeation technique

CERN Document Server

Yamazaki, I M

1999-01-01

An automatic counting system for fission tracks induced in a polycarbonate plastic Makrofol KG (10 mu m thickness) is described. The method is based on the gas transport mechanism proposed by Knudsen, where the gas permeability for a porous membrane is expected to be directly related to its track density. In this work, nitrogen permeabilities for several Makrofol films, with different fission track densities, have been measured using an adequate gas permeation system. The fission tracks were produced by irradiating Makrofol foils with a 252Cf calibrated source in a 2 pi geometry. A calibration curve fission track number versus nitrogen permeability has been obtained, for track densities higher than 1000/cm sup 2 , where the spark gap technique and the visual methods employing a microscope, are not appropriate for track counting.

Obsidian dating by fission track method

International Nuclear Information System (INIS)

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

Optical efficiency for fission fragment track counting in Muscovite solid state track recorders

International Nuclear Information System (INIS)

Roberts, J.H.; Ruddy, F.H.; Gold, R.

1984-01-01

In order to determine absolute fission rates from thin actinide deposits placed in direct contact with Muscovite Solid State Track Recorders, it is necessary to know the efficiency with which fission fragment tracks are recorded. In this paper, a redetermination of the 'optical efficiency', i.e. the fraction of fission events recorded and observed in the Muscovite is reported. The value obtained from a well-calibrated thin deposit of 252 Cf and Muscovite etched about 90 min. in 49% HF at room temperature, is 0.9875 +- 0.0085. Manual counting was used. Preliminary results from a deposit of 242 Pu are also reported, along with preliminary comparisons of track counting with an automated system. Reasons for the discrepancy of the optical efficiency reported here with an earlier measurement are also reported. (author)

Fission-track studies of uranium distribution in geological samples

International Nuclear Information System (INIS)

Brynard, H.J.

1983-01-01

The standard method of studying uranium distribution in geological material by registration of fission tracks from the thermal neutron-induced fission of 235 U has been adapted for utilisation in the SAFARI-1 reactor at Pelindaba. The theory of fission-track registration as well as practical problems are discussed. The method has been applied to study uranium distribution in a variety of rock types and the results are discussed in this paper. The method is very sensitive and uranium present in quantities far below the detection limit of the microprobe have been detected

Optical efficiency for fission-fragment track counting in Muscovite Solid-State Track Recorders

International Nuclear Information System (INIS)

Roberts, J.H.; Ruddy, F.H.; Gold, R.

1983-07-01

In order to determine absolute fission rates from thin actinide deposits placed in direct contact with Muscovite Solid-State Track Recorders, it is necessary to know the efficiency with which fission-fragment tracks are recorded. In this paper, a redetermination of the optical efficiency, i.e., the fraction of fission events recorded and observed in the Muscovite, is reported. The value obtained from a well-calibrated thin deposit of 252 Cf and Muscovite etched about 90 min. in 49% HF at room temperature, is 0.9875 +- 0.0085. Manual counting was used. Preliminary results from a deposit of 242 Pu are also reported, along with preliminary comparisons of track counting with an automated system. Reasons for the discrepancy of the optical efficiency reported here with an earlier measurement are also reported. 5 references, 1 figure, 3 tables

Muon induced fission and fission track dating of minerals

International Nuclear Information System (INIS)

Marques, A.

1988-01-01

The effects of muon induced fission on geological dating of samples by the fission track method are evaluated for the case of muscovite minerals. It is found a small but significant effect, greater for the longer ages. Since calculations are developped under the hypothesis of constant atmosphere and primary cosmic ray flux it is suggested that any discrepancy found in ages of very old material that cannot be accounted for by well known environmental influences, be taken as an indication of variation on either the atmospheric stopping power or the intensity of cosmic radiation along the ages. (author) [pt

Dating by fission tracks in archaeology. 1. Principles and experimental methods

International Nuclear Information System (INIS)

Poupeau, G.; Zuleta, E.

1984-01-01

The principles of dating method by uranium fission tracks are shortly exposed. The conditions of application to the archaeology are discussed, in particular for the volcanic glasses, where the fossil fission tracks are often affected of a beginning of effacement. (L.C.) [pt

The fission track method

International Nuclear Information System (INIS)

Hansen, K.

1990-01-01

During the last decade fission track (FT) analysis has evolved as an important tool in exploration for hydrocarbon resources. Most important is this method's ability to yield information about temperatures at different times (history), and thus relate oil generation and time independently of other maturity parameters. The purpose of this paper is to introduce the basics of the method and give an example from the author's studies. (AB) (14 refs.)

The fission-track analysis: An alternative technique for provenance studies of prehistoric obsidian artefacts

CERN Document Server

Bellot-Gurlet, L; Dorighel, O; Oddone, M; Poupeau, G; Yegingil, Z

1999-01-01

Comparison of fission-track parameters - age and track densities - is an alternative tool for correlating obsidian artefacts with their potential natural sources. This method was applied by different fission-track groups in various regions and results were compared with those obtained using the more popular provenance identification techniques based on chemical composition studies. Hundreds of analyses prove that fission-track dating is a complementary technique which turns out to be very useful, specially when the chemical composition does not fully discriminate different sources. Archaeologically significant results were obtained applying the fission-track analysis in various regions of earth.

The fission-track analysis: An alternative technique for provenance studies of prehistoric obsidian artefacts

International Nuclear Information System (INIS)

Bellot-Gurlet, L.; Bigazzi, G.; Dorighel, O.; Oddone, M.; Poupeau, G.; Yegingil, Z.

1999-01-01

Comparison of fission-track parameters - age and track densities - is an alternative tool for correlating obsidian artefacts with their potential natural sources. This method was applied by different fission-track groups in various regions and results were compared with those obtained using the more popular provenance identification techniques based on chemical composition studies. Hundreds of analyses prove that fission-track dating is a complementary technique which turns out to be very useful, specially when the chemical composition does not fully discriminate different sources. Archaeologically significant results were obtained applying the fission-track analysis in various regions of earth

Fission tracks diameters in glasses

International Nuclear Information System (INIS)

Garzon Ruiperez, L.; Veiguela, J.

1974-01-01

Standard glass microscope slides have been irradiated with fission fragments from the uranium. The etching track conditions have been the same for the series, having changed the etching time only for each specimen. For each glass, a minimum of 250 measurements of the tracks diameters have been made, the distributions of which are the bimodal type. Diameters-etching dependence with time is roughly lineal. Energy determinations have been made with the help of the diameters-energy relations. The calculated values agree very well with the know ones. (author) [es

Fission track dating evidence on tectonic activities of northern Himalaya block

International Nuclear Information System (INIS)

Yuan Wanming; Wang Shicheng; Wang Lanfen

2002-01-01

Fission track ages (FTA) of 4 apatite samples collected from Langkazi to Yarlung Zangbo thrust zone range between 13.6 and 17.2 Ma, reflecting the time of continent-continent collision and differing from previous data. The negative correlation between the FTA and sample elevations shows there was rapid uplifting during the continent-continent collision with uplifting rate of 176 m/Ma. Denudation degree, denudation rate and cooling rate were ∼2.9 km, 213 m/Ma and 7 degree C/Ma respectively since 13.6 Ma. FTA of 3 zircon samples are different significantly and have x 2 test value of < 0.1%, confirming the orogeny within continent went under low temperature

Fission track imaging of the Australian continent

International Nuclear Information System (INIS)

Gleadow, A.; Kohn, B.; O'Sullivan, P.; Brown, R.; Gallagher, K.

1999-01-01

Full text: Techniques to reconstruct the thermal histories of rocks in the low-temperature environment of the upper crust have previously found important applications in such areas as sedimentary basin analysis, the evolution of convergent orogenic belts and studies of extensional tectonic environments. Increasingly large sets of thermochronology data are now becoming available on an even larger scale from the apatite fission-track system (for temperatures <∼110 deg C). Additional information is also now starting to emerge at even lower temperatures (<∼75 deg C) from the apatite (U-Th)/He system. The results from such systems can be used in novel ways to examine and visualise the evolution of the upper part of the continental crust. Quantitative modelling has brought a new dimension to this work and forward-modelling procedures are now well established which give 'best fit' thermal histories for temperatures less than about 110 deg C. In many cases the modelled thermal histories provide a proxy for rock transport towards the surface as overlying material is removed by denudation. Such information allows a reconstruction of the denudation history of the land surface. Applying these modelling procedures to large regional arrays of fission-track data means that the thermal history information can now be integrated with other regional data sets to provide an important new perspective on crustal and surface evolution. Apatite fission track analysis has now been completed on nearly 3000 surface outcrop samples across Australia under an AGCRC project to image the thermotectonic evolution of the exposed basement rocks of the continent. The samples analysed are mostly from rocks of broadly granitic composition and the apatites separated from these are overwhelmingly fluorapatites, which are consistent in their fission-track annealing properties with those on which the numerical annealing models are based. By interpolating the calculated thermal histories a series of

Age and significance of core complex formation in a very curved orogen: Evidence from fission track studies in the South Carpathians (Romania)

Science.gov (United States)

Fügenschuh, B.; Schmid, S. M.

2005-07-01

Twenty-four new zircon and apatite fission track ages from the Getic and Danubian nappes in the South Carpathians are discussed in the light of a compilation of published fission track data. A total of 101 fission track ages indicates that the Getic nappes are generally characterized by Cretaceous zircon and apatite fission track ages, indicating cooling to near-surface temperatures of these units immediately following Late Cretaceous orogeny. The age distribution of the Danubian nappes, presently outcropping in the Danubian window below the Getic nappes, depends on the position with respect to the Cerna-Jiu fault. Eocene and Oligocene zircon and apatite central ages from the part of the Danubian core complex situated southeast of this fault monitor mid-Tertiary tectonic exhumation in the footwall of the Getic detachment, while zircon fission track data from northwest of this fault indicate that slow cooling started during the Latest Cretaceous. The change from extension (Getic detachment) to strike-slip dominated tectonics along the curved Cerna-Jiu fault allowed for further exhumation on the concave side of this strike-slip fault, while exhumation ceased on the convex side. The available fission track data consistently indicate that the change to fast cooling associated with tectonic denudation by core complex formation did not occur before Late Eocene times, i.e. long after the cessation of Late Cretaceous thrusting. Core complex formation in the Danubian window is related to a larger-scale scenario that is characterized by the NNW-directed translation, followed by a 90° clockwise rotation of the Tisza-Dacia "block" due to roll-back of the Carpathian embayment. This led to a complex pattern of strain partitioning within the Tisza-Dacia "block" adjacent to the western tip of the rigid Moesian platform. Our results suggest that the invasion of these southernmost parts of Tisza-Dacia started before the Late Eocene, i.e. significantly before the onset of Miocene

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.

Induced fission track distribution from highly radioactive particles in fallout materials

International Nuclear Information System (INIS)

Hashimoto, Tetsuo; Okada, Tatemichi

1987-01-01

Some highly radioactive fallout particles (GPs) from the 19th Chinese nuclear detonation were followed to the neutron irradiation in a reactor after sandwiched with mica detectors. The interesting star-like fission track patterns were revealed on the etched surface of the mica detectors. The simple chemical separation procedure for the GPs was applied for the separation of U and Pu as fissile elements and the both resultant fractions were examined with the similar high sensitive fission tracking detection. Subsequently, a representative track pattern from a black spherical particle was subjected to the determination of fissile nuclide content; comparing the total fission events evaluated on the basis of the numerical calculation of track densities with the total thermal neutron fluence. The results implied that the uranium is responsible for the main fissile nuclide remaining within a particle as unfissioned fractions and should be certainly enriched with respect to U-235 within such small fallout particles. This sophisticated method was also applied to determine the dead GPs, which have been highly radioactive particles just after the detonations, in the rain and snow-residual materials. Many induced star-like fission tracks verified certainly that there remains a lot of dead particles in the atmosheric environment till nowadays. (author)

Characterization of aerosols containing fissionable elements using solid-state track recorders

International Nuclear Information System (INIS)

Roberts, J.H.; Kafalenos, V.P.; Yule, T.J.

1976-01-01

An aerosol of U 3 O 3 highly enriched in 235 U was generated with a nebulizer from a suspension of U 3 O 8 powder in distilled water. The aerosol was collected on a membrane filter. Polycarbonate plastic, placed in good contact with the filter, was used to record fission tracks when the package was exposed to known fluences of slow neutrons. Fission-track stars associated with individual particles of U 3 O 8 were observed in the plastic. The fission-track distributions were converted to a particle size distribution for the aerosol. For a log normal distribution the geometric mean and standard deviation can be determined with better than 5% accuracy. This method can be applied to plutonium and other transuranic aerosols. (orig.) [de

Denudation history of the Snowy Mountains: constraints from apatite fission track thermochronology

International Nuclear Information System (INIS)

Kohn, B.P.; Gleadow, A.J.W.; Cox, S.J.D.

1999-01-01

Apatite fission track thermo chronology from Early Palaeozoic granitoids centred around the Kosciuszko massif of the Snowy Mountains, records a denudation history that was episodic and highly variable. The form of the apatite fission track age profile assembled from vertical sections and hydro-electric tunnels traversing the mountains, together with numerical forward modelling, provide strong evidence for two episodes of accelerated denudation, commencing in Late Permian - Early Triassic (ca 270 250 Ma) and mid-Cretaceous (ca 110-100 Ma) times, and a possible third episode in the Cenozoic. Denudation commencing in the Late Permian - Early Triassic wins widespread in the eastern and Central Snowy Mountains area, continued through much of the Triassic, and amounted to at least ∼2.0-2,4 km. This episode was probably the geomorphic response to the Hunter-Bowen Orogeny. Post-Triassic denudation to the present in these areas amounted to ∼2.0-2.2 km. Unambiguous evidence for mid-Cretaceous cooling and possible later cooling is confined to a north-south-trending sinuous belt, up to ∼15km wide by at least 35km long, of major reactivated Palaeozoic faults on the western side of the mountains. This zone is the most deeply exposed area of the Kosciuszko block. Denudation accompanying these later events totalled up to ∼1.8-2.0 km and ∼2.0 2.25 km respectively. Mid-Cretaceous denudation marks the onset of renewed tectonic activity in the south-eastern highlands following a period of relative quiescence since the Late Triassic, and establishes a temporal link with the onset of extension related to the opening of the Tasman Sea. Much of the present day relief of the mountains resulted from surface uplift which disrupted the post-mid-Cretaceous apatite fission track profile by variable offsets on faults. Copyright (1999) Geological Society of Australia

Fission distribution measurements of Atucha's fuel pellets with solid state track detectors

International Nuclear Information System (INIS)

Ricabarra, M.D. Bovisio de; Waisman, Dina.

1979-08-01

Distribution of fissions in a UO 2 rod has been measured by means of solid state detectors. Mica muscovite and Makrofol-N detectors were used in the experiment. The merits of mica muscovite relative to the Makrofol-N for the detection of fission fragments have been verified. However both fission track detectors closely agree (0,5%) in the final fission distribution of the UO 2 rod. Sensitivity of the detectors shows to be linear in the range between 50.000and 360.000 fission tracks per square centimeter. Due to the high spatial resolution this method is better than any other technique. Determination were made in UO 2 pellets similar to the fuel element of the Atucha reactor. The average fission rate in the rod has been measured within 0,8% error, and provides an accurate determination for the distribution of fissions in the rod wich is needed for the determination of energy liberated per fission in the natural uranium rod.(author) [es

Fission track thermochronology : reconstructing the thermal and tectonic evolution of the crust

International Nuclear Information System (INIS)

Gleadow, A.J.W.

1990-01-01

The basis and current status of fission track analysis is reviewed showing the kinds of patterns of fission track parameters which result from a variety of thermal and tectonic histories. Fission track thermochronology is a well established method for reconstructing the thermal histories of rocks with particularly important applications in tectonic studies. Quantitative modelling of the thermal annealing of tracks in apatite shows that distinctive profiles of apparent fission track age can be related to a number of simple thermal history styles. The main types of profiles observed tend to be either an essentially linear decrease of apparent age with increasing depth, which relates to continuous uplift and denudation, or a concave-upwards profile produced by partial annealing in environments of tectonic stability or burial. More complex thermal histories produce compound profiles which are essentially just combinations of these two elements. Track length information allows the apparent age profiles to be interpreted in much greater detail. Examples of the major profile types have been identified in various geological environments and can be analysed to give information about, for example, uplift and denudation rates, the timing of uplift or low-grade thermal events and maximum palaeotemperatures experienced during burial. 25 refs., 8 figs

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.

The thermal history of the Bowen Basin: a comparison of apatite fission track analysis and vitrinite reflectance

International Nuclear Information System (INIS)

Marshallsea, S.J.

1987-01-01

Vitrinite reflectance and apatite fission-track analysis (AFTA) are two techiques widely used to assess paleotemperatures of the order of 20-120 deg.C. in sedimentary basins. Whereas vitrinite reflectance is essentially a qualitative technique that gives an integrated measure of the entire thermal history, AFTA can reveal information on the variation of paleotemperatures through time because fission-tracks in apatite are continually produced throughout geological time. An apatite fission track study of the Upper Permian units of the Bowen Basin has offered the opportunity to compare the two paleotemperature indicators and place constraints on the timing of maximum paleotemperatures. The regional pattern of apatite fission-track ages closely coincides with the vitrinite reflectance indicating that maximum paleotemperatures have varied across the Basin with the central region of the Bowen Basin experiencing highest paleotemperatures. The reduction in apatite reflectance fission-track age with increasing reflectance represents the progressive annealing at temperatures around 60-120 deg. C. of those fission-tracks formed prior to the time of maximum temperatures. In those samples giving the youngest apatite fission-track ages all tacks were totally annealed at this time, and the fission-track age in these samples, in the range 90-120 Myr, indicate the time of cooling from the thermal maximum in the Early Cretaceous. 1 ref

Studies on fission tracks and distributions of uranium and rare earths in granite materials

International Nuclear Information System (INIS)

Matsuda, Hiroshi; Sakanoue, Masanobu

1987-01-01

Many materials contain fossil records of the slow spontaneous fission of uranium they contain as an impurity. Fission fragments, heavy charged particles released in each fission event, produce microscopic trails of radiation damage that may persist over geological times and may be developed to a size observable under an optical microscope by a suitable etching treatment. Such tracks are also produced by fissions induced by thermal neutron irradiation of the uranium. When the material is heated sufficiently, it anneals and the the microscopic trails become shorter and narrower. The track density decreases, because the chemical etchant will not reach some of the shortened tracks. Measurements of track densities before and after annealing can be used, along with laboratory studies of annealing rates, to determine the annealing temperature. Also, the track density of induced fissions is related to the concentration of uranium and the fluence of neutrons to which it was exposed. If the track density due to induced fissions can be distinguished from that due to fossil tracks, estimates of either the concentration or the fluence can be made if the other is known. Two such materials (one a fragment of a granite paving stone, the other a piece of stained glass from a cathedral window) that had been exposed to the atomic bomb at Nagasaki were used in the present work. The fossil record in zircons in the granite was used to estimate the temperature to which it had been exposed in the bombing. Induced fissions were used to estimate the concentration of uranium in the zircons. Nonuniform heating and cooling and nearly uniform exposure to the neutrons make the granite sample unsuitable for determining the neutron fluence from the bomb. Induced fissions in the stained glass were used to estimate the concentration of uranium and the thermal neutron fluence from the A-bomb. Annealing of tracks in glass was also studied

Thermal significance of fission-track length distributions

International Nuclear Information System (INIS)

Crowley, K.D.

1985-01-01

The semi-analytical solution of an equation describing the production and shortening of fission tracks in apatite suggests that certain thermal histories have unique length-distribution 'signatures'. Isothermal-heating histories should be characterized by flattened, length-shortened distributions; step-heating histories should be characterized by bimodal track length distributions; and linear-cooling histories should be characterized by negatively skewed, length-shortened distributions. The model formulated here to investigate track length distributions can be used to constrain the thermal histories of natural samples for which unbiased track length data are available - provided that the geologic history of the system of interest can be used to partially constrain one of the unknowns in the model equations, time or temperature. (author)

Fission tracks dating for obsidian

International Nuclear Information System (INIS)

Picon, C.

1991-01-01

Obsidian from South America are dated by fission tracks methods. Samples are irradiated in a nuclear reactor with a flux of 10 15 n/cm 2 . Results, corrected by 'Plateau' methods, are the following: obsidian from Bolivia: 4.14 x 10 6 yr., Ecuador: 8.79 x 10 5 yr., Colombia: 3.52 x 10 6 yr., Peru: 6.55 x 10 6 yr., Chile: 1.13 x 10 6 yr. (MMZ). 5 refs., 3 tabs

Apatite fission track dating and thermal history of Qing-He region in Altay Mountains

International Nuclear Information System (INIS)

Bao Zengkuan; Chinese Academy of Sciences, Beijing; Yuan Wanming; Dong Jinquan; Gao Shaokai

2005-01-01

Fission track ages (FTA) and track lengths of apatite from Qing-He diorite intrusion in Altay Mountains are measured. Apatite fission track ages of three diorite samples is range from (78±5) Ma to (95 ± 5) Ma, and the lengths of horizontal confined spontaneous fission tracks are (13.2 ± 1.2)-(13.5 ±1.3) μm. The distribution of the track length is narrow and symmetrical with a mean length of approximately 13.3 μm and a standard deviation of around 0.1 μm. The inverse modeling results show that thermal history of this region has four stages, two rapid uplift of this region still existed magmatic intrusion and tectonic movements in Yanshanian. (authors)

Technique of neutron-induced (fission-track) autoradiography with histological detail

International Nuclear Information System (INIS)

Smith, J.M.; Taylor, G.N.; Jee, W.S.S.

1980-01-01

The primary advantage of neutron-induced or fission-track autoradiography compared with conventional autoradiography is that for low concentrations of fissile nuclides prohibitively long exposure times may be avoided. However, it is difficult to produce imaging of biological structures on the neutron-induced autoradiograph which would allow localization of the nuclide histologically. The technique presented circumvents this difficulty using a thin polycarbonate film applied to the histologically stained tissue section mounted on a quartz substrate. After irradiation of the tissue section with an appropriate thermal neutron flux, the fission fragment tracks are revealed by etching the film with KOH. The tracks, superimposed on the stained tissue, may be observed under the light microscope in the same manner as for conventional nuclear emulsion autoradiography

Observations of fission-tracks in zircons by atomic force microscope

International Nuclear Information System (INIS)

Ohishi, Shinnosuke; Hasebe, Noriko

2012-01-01

The fission-track (FT) method is a dating technique based on the observation of damage (tracks) by spontaneous fission of 238 U left in a mineral. The date is calculated from the track density and the uranium concentration in the mineral. This is possible because the number of tracks is a function of uranium concentration and time since the start of track accumulation. Usually, the number of tracks is counted under an optical microscope after etching (chemical expansion of a track). However, as FT density per unit area rises, it becomes difficult to count the number of tracks. This is due to the fact that FTs overlap one another and are unable to be readily distinguished. This research examines the potential of atomic force microscope (AFM) for FT dating using zircons, which are likely to show higher FT density than other minerals due to their high U concentrations. To obtain an AFM image for a sample prepared for FT dating, removing the static electricity of the sample is essential to avoid an unexpected movement of the cantilever. A grain should be wider than about 30 μm to bring the cantilever on the mineral surface. Polishing with a fine grained compound is very important. There is not much difference in sharpness between images by AC mode (scanning with vibrating cantilever at a constant cycle) and Contact mode (scanning with the cantilever always in close contact with the surface). To confirm how tracks can be identified with the AFM, an AFM image was compared with an image obtained with the optical microscope. When change in the number of tracks and their shapes were observed through stepwise etching, the track expanded as the etching time increased. In addition, the etching rate was slower for large tracks than those for small tracks. This implied that the AFM can be used to observe etching of zircons with different degrees of nuclear fission damage. A track that could not be seen with the optical microscope due to insufficient etching could be observed by

Dating by fission track method: study of neutron dosimetry with natural uranium thin films

International Nuclear Information System (INIS)

Iunes, P.J.

1990-06-01

Fission track dating is described, focalizing the problem of the decay constant for spontaneous fission of 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

Contribution of the fission-track method to the study of the Alpine chains: relationship between tectonics and metamorphism

International Nuclear Information System (INIS)

Carpena, J.

1984-01-01

The fission-track method allows geologists to date rocks and to get information on the thermal history of rocks. Fission tracks in minerals are essentially due to the spontaneous fission of uranium 238. The knowledge of the density of tracks and the concentration of uranium 238 lead to the determination of the age of the rock. The irradiation in a neutron flux of a sample of the rock allows the determination of the concentration of uranium. The age obtained is in fact an apparent age that does not take into account possible geological annealing process that may erase fission tracks, some corrections are then necessary. The first part of this work details the fission-track method, its scope and limitations. It is shown that fission-track method on apatites can reveal the thermal evolution of the rock and that the same method used on zircons can give information of the setting of volcanic rocks. The second part is dedicated to the contribution of the fission-track method to a both dating and thermal evolution study of a french-italian part of the Alpine chain

Inverse modelling of thermal histories with apatite fission tracks

International Nuclear Information System (INIS)

El Lmrani, A.; Zine El Abidine, H.; Limouri, M.; Essaid, A.; POupeau, G.

1998-01-01

The problem of modelling thermal histories lies in the exploration of a time-temperature space, usually so broad, in order to identify the optimal paths. For overcoming this difficulty, many approaches were proposed, using linear and non-linear optimisation algorithms. Generally, these approaches do not take into account the experimental data (fission track age [FTA] and fission track length distribution [FTLD]) to better aim the search strategy. The present work shows that experimental data hold some precious information, for which it should be known how to extract it. In fact, it allows us to tighten the time-temperature space of search, supposed to contain the optimal solutions. A genetic algorithm is also used in this work to perform the search for these optimal solutions. (authors)

Etching of fission tracks in silicate glasses by means of deionized water

International Nuclear Information System (INIS)

Dran, J.C.; Petit, J.C.

1985-09-01

Fission tracks have been revealed in silicate glasses with deionized water. Their sharp conical shape implies a marked enhancement of the dissolution rate along their core and consequently a cone angle and an etching efficiency (close to 100%) much higher than previously reported for glasses. We show that etching of fission tracks in natural environments has generally very limited geochemical implications except in specific cases such as that found in the Oklo uranium ores

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.

On the frequency distributions per unit area of the projected and etchable lengths of surface-intersecting fission tracks: influences of track revelation, observation and measurement

International Nuclear Information System (INIS)

Jonckheere, R.; Haute, P. van den

1999-01-01

In addition to the statistical bounds discussed, thermal history analysis based on the projected and etchable length distributions of surface intersecting fission tracks is limited by systematic factors related to track revelation, observation and measurement. The effects of track revelation, in particular, distort these distributions in the length intervals of interest. An observation threshold poses a problem if it is described by a critical angle θ c , but not if it is described by other criteria proposed in the literature. Measurement imprecisions, predictably, blur the thermal history information contained in these distributions. Measurements of semi-confined tracks, added as a result of surface etching, are a more promising alternative to confined track length measurements for accessing the thermal history record in the fission track length distribution. On the other hand, measurements of the projected lengths of surface intersecting tracks offer the theoretical possibility of determining the true volumetric density N and true mean length m of an arbitrary population of fission tracks, thus allowing direct determination of the corrected age of samples with complex thermal histories. On a methodical level, knowledge of N and m allows to determine the efficiency with which fission tracks are counted under the optical microscope under exactly the same conditions as those under which fission track counts for routine dating purposes are performed

Fission-track dating of apatite from deep borehole ATK-1 at Atikokan, Ontario

International Nuclear Information System (INIS)

Naeser, C.W.; Crowley, K.D.

1990-01-01

Fission-track age and lengths have been determined on apatite separated from core recovered from the ATK-1 deep borehole at Atikokan, Ontario. The apatite ages decrease down the borehole, from 515 ± 72 Ma at the top to 376 ± 46 Ma at a depth of 993 m. The mean confined track length for fossil fission tracks in the apatite is 12.4 μm. Within the limits of the measurement the track lengths are the same for all the samples. The results of this study indicate that the rocks found currently at the surface have never been heated above ∼100C since Upper Cambrian time

Critical angles for fission fragment registrations in some solid state track detectors

Energy Technology Data Exchange (ETDEWEB)

Belyaev, A D; Bahromi, I I; Beresina, N V [AN Uzbekskoj SSR, Tashkent. Inst. Yadernoj Fiziki; and others

1980-03-01

In studies of the registration efficiency of various solid state track detectors (polycarbonate, polyethyleneterephthalate, cellulose nitrate and muscovite) the detectors were irradiated with spontaneous fission fragments from /sup 252/Cf and with fission fragments from /sup 235/U separated according to mass and energy. Experimental details are given. Critical angles for the registration of fission fragments in the various detectors are given for specified energies and masses.

The changing face of fission track dating: recent advances

International Nuclear Information System (INIS)

Green, P.F.; Duddy, I.R.; Gleadow, A.J.W.; Laslett, G.M.; Hegarty, K.A.; Lovering, J.F.

1985-01-01

Fission Track Dating has undergone something of a renaissance in recent years. What began as a rather unreliable method of geochronology has now become a rigorous and dependable means of measuring not only geological time but also paleotemperatures. Developments such as the zeta calibration technique, rigorous satistical data analysis, investigation of confined track lengths and detailed studies of annealing behaviour have all contributed to advances in the technique

Fission track dating: methodology and thermo-chronological applications in alpine and continental margin contexts

International Nuclear Information System (INIS)

Sabil, N.

1995-06-01

The fission track dating method has proved to be unique in thermo-chronology by its capability to describe the final phases of the cooling history and denudation of metamorphic massifs, like the thermal history of sedimentary formations or the dating of some volcanic materials. In this work we describe this method and present a series of new analytic techniques and calibrations which we realised in the aim of further use in geology. We discuss a few examples of such applications. In the french Occidental Alps, the analysis of fission track on apatite samples from the granites of the Sept Laux (Belledonne massif), in the Eau d' Olle valley, suggests that this method could bring a contribution to the actual discussion about the origin of some alpine valleys. The fission track method suggests that the opening of this valley could be the consequence of an active faulting from the middle Miocene until the present. The characterization of fluvial deposits through their detrital apatites fission tracks record could eventually be used to study river captures related to changes tectonic regimes. Therefore we studied the apatites of a paleo-delta located in the Isere middle valley at the sub-alpine 'sillon' level, and of two valleys, those of the Arc and of the Breda, located up the delta. The distribution of the fission track ages of those mineraIs has not confirmed a previously suggested model, which proposed that the studied paleo-delta could be associated with a paleo-Arc rather than a paleo-Breda. In the Moroccan Occidental Meseta, three granitic massifs located in the Rehamna have been selected for a thermo-chronological study. The analysis of the fission track in zircons and apatites of these granites recorded the thermo-tectonic events which have affected the Meseta ever since the opening of the Central Atlantic Ocean some 200 Ma ago. We show how a numerical simulation model recently (1994) proposed for the analysis of fission track in apatites allows us to specify

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.

Irradiation positions for fission-track dating in the University of Pavia TRIGA Mark II nuclear reactor

International Nuclear Information System (INIS)

Oddone, Massimo; Meloni, Sandro; Balestrieri, Maria Laura; Bigazzi, Giulio

2002-01-01

An irradiation position arranged is described in the present paper for fission-track dating in the Triga Mark II reactor of the University of Pavia. Fluence values determined using the NIST glass standard SRM 962a for fission-track dating and the traditional metal foils are compared. Relatively good neutron thermalization (φ th /φ f = 0.956) and lack of significant fluence spatial gradients are good factors for fission-track dating. Finally, international age standards (or putative age standards) irradiated in this new position yielded results consistent with independent reference ages. (author)

Solid state nuclear track detectors in the measurement of alpha to fission branching ratios of heavy actinides

International Nuclear Information System (INIS)

Pandey, A.K.; Sharma, R.C.; Padalkar, S.K.; Kalsi, P.C.; Iyer, R.H.

1992-01-01

A sequential etching procedure for revelation of alpha and fission tracks in CR-39 was developed and optimized. Using this technique alpha and fission tracks can be differentiated unambiguously because of significant differences in their sizes and etching times. This registration and revelation procedure for alpha and fission tracks may be used for the studies of half lives, alpha to fission branching ratios and identification of radionuclides based on their decay schemes. It has the added advantage that both alpha decay and fission events can be studied using one detector and hence uncertainties related to efficiency, registration geometry, registration times, amount of radionuclides etc can be eliminated or minimized. The effects of neutron, gamma and alpha radiations on the alpha and fission fragment tracks registration and revelation properties of CR-39 detectors [CR-39, CR-39 (DOP)] were also studied. The IR spectra were also studied to find out the nature of chemical changes produced by these radiations on CR-39. (author). 32 refs., 7 figs., 4 tabs

Natural uranium impurities in fission track detectors and associated geocronological parameters

International Nuclear Information System (INIS)

Ricabarra, G.H.; Bovisio de Ricabarra, M.D.; Waisman, Dina; Faradjie de Turjanski, Rosa

1981-01-01

A technique, based in counting neutron induced fission tracks, has been developed for the measurement of uranium impurities in mica. Uranium concentrations of 10 -10 and 10 -9 (U atom/mica atom) have been measured. As a part of the development of this technique, the mica geological age was also measured, by fossil and induced track detection. The agreement obtained by this method, T = (472+-52) x 10 6 years with that of (450+-15) x 10 6 years obtained by the Ar-K technique is satisfactory and is an indirect test of the fission track technique used. A careful analysis of the neutron field parameters and nuclear data used in the age determination was made. This analysis is useful for applications in geocronology. According to this analysis a value of lambdasub(f)=(7.1+-0.1) x 10 -17 years -1 is recommended for the spontaneous fission of U238. However, in order to compare the results, the quoted age, T=(472+-52) x 10 6 years, was obtained with the generally accepted value of lambdasub(f)=(6.85-0.20) x 10 -17 years -1 (Fleischer and Price 1964). (author) [es

The quantitative determination of uranium in human hair by fission track measurements

International Nuclear Information System (INIS)

Wilson, D.J.; Bentley, K.W.

1985-01-01

Human hairs containing a uranium burden were placed in contact with a mica sheet as the recording matrix and irradiated in a thermal neutron flux. The fission fragment tracks penetrating the mica were etched and counted. Calculations have been made to show the losses due to the fission fragment range being less than the diameter of the hair and for the variation of track density with distance from the line of contact between the hair and the mica. Experimental data from 50 μm diameter hair and those derived by calculation were compared. (author)

A new look at statistics in fission-track dating

International Nuclear Information System (INIS)

Green, P.F.

1981-01-01

Poissonian errors, as routinely applied in fission-track dating, represent a limiting case, which may not always be attainable in practice. Other experimental factors may introduce additional non-Poissonian errors, which must be taken into account. In the population method, sampling of non-homogeneous uranium distributions introduces experimental error. In the external detector method (EDM), many factors exist to introduce such error. Simply quoting total numbers of spontaneous and induced fission tracks obtained by the EDM may disguise the possible influence of experimental variation. The present work concentrates on the EDM, and describes a test which has recently been proposed to detect the presence of experimental error in EDM analyses. The question of an alternative analysis for cases where such error is present is also considered. A method of presenting EDM data is suggested, which allows assessment of the importance of experimental errors. (author)

Mesozoic-Cenozoic tectonic evolution and its relation to sandstone-type uranium mineralization in northern Tarim area--Evidence from apatite fission track

International Nuclear Information System (INIS)

Liu Hongxu; Dong Wenming; Liu Zhangyue; Chen Xiaolin

2009-01-01

The apatite fission track dating and inversion result of geological thermal history of four rock specimens from Sawafuqi area and Talike area in northern Tarim Basin show that two areas uplifted at different ages. The apatite fission track ages of Sawafuqi range from 3.5 to 3.9 Ma, while the ages of Talike range from 53 to 59 Ma. The thermal history recorded by rock samples reveals that there are at least three prominent cooling phases since Late Cretaceous epoch. Detailed study was made on the division of uplifting stages during Mesozoic and Cenozoic tectonic evolution with the existing data in northern Tarim area. And new ideas on tectonic evolution and sandstone-type uranium mineralization have been put forward by combining with the sandstone-type uranium mineralization ages in this area.(authors)

Quantitative Identification of the Annealing Degree of Apatite Fission Tracks Using Terahertz Time Domain Spectroscopy (THz-TDS).

Science.gov (United States)

Wu, Hang; Wu, Shixiang; Qiu, Nansheng; Chang, Jian; Bao, Rima; Zhang, Xin; Liu, Nian; Liu, Shuai

2018-01-01

Apatite fission-track (AFT) analysis, a widely used low-temperature thermochronology method, can provide details of the hydrocarbon generation history of source rocks for use in hydrocarbon exploration. The AFT method is based on the annealing behavior of fission tracks generated by 238 U fission in apatite particles during geological history. Due to the cumbersome experimental steps and high expense, it is imperative to find an efficient and inexpensive technique to determinate the annealing degree of AFT. In this study, on the basis of the ellipsoid configuration of tracks, the track volume fraction model (TVFM) is established and the fission-track volume index is proposed. Furthermore, terahertz time domain spectroscopy (THz-TDS) is used for the first time to identify the variation of the AFT annealing degree of Durango apatite particles heated at 20, 275, 300, 325, 450, and 500 ℃ for 10 h. The THz absorbance of the sample increases with the degree of annealing. In addition, the THz absorption index is exponentially related to annealing temperature and can be used to characterize the fission-track volume index. Terahertz time domain spectroscopy can be an ancillary technique for AFT thermochronological research. More work is urgently needed to extrapolate experimental data to geological conditions.

Disintegration constant of uranium-238 by spontaneous fission redetermined by glass track method

International Nuclear Information System (INIS)

Lima Medeiros, E. de.

1978-01-01

The disintegration constant of U 238 by spontaneous fission using glass as fission fragment detector was redetermined. A film of natural uranium (UO 3 ) prepared by chemical methods on the glass lamina was used in a long time experience of exposure (about 16 years). The good conditions of sample preparation and storage allow to observe, after chemical etching, fission fragment tracks. (M.C.K.) [pt

U and Th thin film neutron dosimetry for fission-track dating: application to the age standard Moldavite

International Nuclear Information System (INIS)

Iunes, P.J.; Bigazzi, G.; Hadler Neto, J.C.; Laurenzi, M.A.; Balestrieri, M.L.; Norelli, P.; Osorio Araya, A.M.; Guedes, S.; Tello S, C.A.; Paulo, S.R.; Moreira, P.A.F.P.; Palissari, R.; Curvo, E.A.C.

2005-01-01

Neutron dosimetry based on U and Th thin films was used for fission-track dating of the age standard Moldavite, the central European tektite, from the Middle Miocene deposit of Jankov (southern Bohemia, Czech Republic). Our fission-track age (13.98+/-0.58Ma) agrees with a recent 40 Ar/ 39 Ar age, 14.34+/-0.04Ma, based on several determinations on Moldavites from different sediments, including the Jankov deposit. This result indicates that the U and Th thin film neutron dosimetry represents a reliable alternative for an absolute approach in fission-track dating

Fission track dating method: I. Study of neutron flux uniformity in some irradiation positions of IEA-R1 reactor

International Nuclear Information System (INIS)

Osorio, A.M.; Hadler, J.C.; Iunes, P.J.; Paulo, S.R. de

1993-06-01

In order to use the fission track dating method the flux gradient was verified within the sample holder, in some irradiation positions of the IEA-R1 reactor at IPEN/CNEN, Sao Paulo. The fission track dating method considers only the thermal neutron fission tracks, to subtract the other contributions sample irradiations with a cadmium cover was performed. The neutron flux cadmium influence was studied. (author)

Studies on the Th biodistribution in internal contamination by the fission track method using animals

International Nuclear Information System (INIS)

Ciubotariu, M.; Danis, A.; Dumitrescu, G.; Cucu, M.

1998-01-01

In our previous studies on the U internal contamination, qualitative and quantitative results were obtained by using the fission track methods. In order to obtain complete data on the fissionable element internal contamination using animals, we started a similar study using Th as contaminating element and Wistar London breed rats as laboratory animals. Different ways to obtain internal contaminations were investigated: ingestion, inhalation, absorption by skin and through wounds. In this stage, Wistar-London breed rats of the same sex, weight and age were internal contaminated by 1 ml Th solution ingestion for each rat corresponding to an Annual Limit Intake.The animals were kept in normal life conditions and under permanent medical surveillance up to their sacrifice. Also, their evacuations where sampled every 24 hours. They were sacrificed at different time intervals after their contamination: 2 days (RAT 1), 7 days (RAT 2) and 14 days (RAT 3). After sacrifice, their vital organs were sampled, weighed, calcined, reweighed and finally analysed by track detection using the fission track micromapping technique. This technique was used in the following conditions: - mica-muscovite as track detector pre-etched for fossil tracks 18 h in HF; - the neutron irradiations were performed in the nuclear reactor VVR-S Bucharest at the neutron fluences of 3x10 15 - 2x10 16 fast neutrons/cm 2 . In order to check whether there is any U contribution to the fission track densities obtained in track detectors, U existing in the rat body due to food and water, the neutron irradiations of the ensembles were performed with and without 1 mm Cd shielding; - the visualization of the Th induced fission tracks were obtained by chemical etching in HF, 3 h at room temperature; - the Th track micromappings obtained in track detectors were studied by optical microscopy using a stereomicroscope WILD M7S for ensemble study (X6-X31) and a binocular ZEISS JENA microscope for qualitative and

Chemical etching of fission tracks in ethylene-tetrafluoroethylene copolymer

International Nuclear Information System (INIS)

Komaki, Y.; Tsujimura, S.; Seguchi, T.

1979-01-01

The chemical etching of fission tracks in ethylene-tetrafluoroethylene copolymer was studied. Etched holes 3000 to 4000 A in diameter were recognized by electron microscopy for a film bombarded by fission fragments in oxygen and etched in a 12N sodium hydroxide solution at 125 0 C. The radial etching rate at 125 0 C was 6 to 8 A/hr, which is less than 17 A/hr for polyvinylidene fluoride in the same sodium hydroxide concentration at 85 0 C. The smaller rate is a reflection of the larger chemical resistivity of ethylene-tetrafluoroethylene copolymer than polyvinylidene fluoride. (author)

Radiation damage studies of mineral apatite, using fission tracks and thermoluminescence techniques

International Nuclear Information System (INIS)

Al-Khalifa, I.J.M.

1988-01-01

In a uranium (/thorium)-rich mineral sample which has not suffered a recent geological high-temperature excursion, the fossil fission track density (FFTD) will give a good indication of its natural radiation damage, provided that its U/Th ratio is known. From our studies of FFTD and thermoluminescence (TL) properties of several samples of apatite from different locations, and containing varying degrees of natural-radiation damage, an anti-correlation is observed between FFTD and TL sensitivity. It is also found that an anti-correlation exists between TL sensitivity and the amount of damage produced artificially by bombarding apatite crystals with different fluences of ∼30 MeV α-particles from a cyclotron. These results indicate that the presence of radiation damage in this mineral (viz., fluorapatite) can severely affect its TL sensitivity (i.e. TL output per unit test dose). The effect of crystal composition on the thermoluminescence and fission track annealing properties of mineral apatite is also reported. We have found that fission track annealing sensitivity and TL sensitivity are both significantly lower in samples of chlorapatite than in samples consisting predominantly of fluorapatite. (author)

Determination of the uranium concentration in soil solutions by the fission track registration technique

International Nuclear Information System (INIS)

Fernandes, G.P.

1980-02-01

The fission tracks registration technique was used to determine the uranium concentration in soil solutions. The Makrofol KG, a synthetic plastic manufactured by Bayer, was used as a detector and the wet method was applied. From the calibration curves obtained, it was possible to determine uranium concentrations in soil solutions, from 90 to 320 μg U/l, with an error between 9.4% and 4.0%, respectively. The method was applied to a few soil samples from Pocos de Caldas, Minas Gerais in Brazil. The uranium concentrations in the sample and residues were also determined by other methods to compare the results obtained; only one sample showed deviation from the results obtained by the fission tracks method. And this discrepancy was explained in a reasonable way. It was shown that the fission tracks technique can be used with sucess for application in soil solutions. (Author) [pt

Fission-track ages of Neogene and Quaternary volcanic ashes in south of Osaka, Japan

International Nuclear Information System (INIS)

Yokoyama, Takuo; Nakagawa, Yonosuke; Danhara, Tohru.

1984-01-01

A calculation method is proposed for the fission-track ages of zircon crystals in volcanic material. In this method, it is checked whether the spontaneous fission-track number of respective zircon crystals follows the Poisson distribution. If it does, the age is calculated by population method with all crystals, and if not, only with those crystals following the Poisson distribution, eliminating abnormal crystals. Extraneous zircon crystals are thus excluded and crystals with spontaneous fission-track number zero are not ignored. The following ages were obtained: Tamateyama volcanic ash in the Nijo group, 14.0 +- 0.6 Ma; pink volcanic ash in the Osaka group, 1.0 +- 0.2 Ma; Matsuo volcanic ash in the Ko-Osaka group, 1.5 +- 0.4 Ma; pumice volcanic ash in the Ko-Osaka group, 2.3 +- 0.4 Ma; Asashiro volcanic ash in the Ko-Osaka group, 2.9 +- 0.6 Ma. (Mori, K.)

Application of fission track and other new technics in the study of geothermal history for Liaohe Basin

International Nuclear Information System (INIS)

Xia Yuliang; Zhu Jiechen; Zheng Maogong; Zhao Yunlong; Hu Zhenduo; Guo Xiuying; Gao Shangkui

1994-11-01

Mainly based on the study of fission track of the apatites, as well as geochronology, stable isotope composition and inclusion analysis, the principle and method of studying the geothermal history of sedimentary basin have been expounded systematically, and the source of sediment materials, and the geothermal characteristics of five section areas in Liaohe Basin were determined. The results of apatites and zircons U-Pb dating indicate that the materials of Shahejie Group in Liaohe Basin derived from the Shanhaiguan old land, and the record time of fission track of the apatites started at 172 Ma ago. On the basis of the studies of fission track characters of 100 apatite samples, stable isotopes and inclusion analysis, the annealing zone of fission track, oil generation zone and the old geothermal gradient were determined respectively in the western slope, southern part of western depression, Niuju area, Huangjindai area of eastern depression and Shallow sea area. It has provided the important scientific basis of reevaluating oil resources in Liaohe Basin. (2 tabs.)

Solid State Track Recorder fission rate measurements at high neutron fluence and high temperature

International Nuclear Information System (INIS)

Ruddy, F.H.; Roberts, J.H.; Gold, R.

1985-01-01

Solid State Track Recorder (SSTR) techniques have been used to measure 239-Pu, 235-U, and 237-Np fission rates for total neutron fluences approaching 5 x 10 17 n/cm 2 at temperatures in the range 680 to 830 0 F. Natural quartz crystal SSTRs were used to withstand the high temperature environment and ultra low-mass fissionable deposits of the three isotopes were required to yield scannable track densities at the high neutron fluences. The results of these high temperature, high neutron fluence measurements are reported

Dating method by fission tracks: some Brazilian examples

International Nuclear Information System (INIS)

Fonseca, Ariadne do Carmo

1996-01-01

The Fission Track method (TF) complements the dating of a interval of tectonic events occurred in low temperatures not detected by another radiometric methods. In the South part of Craton of Sao Francisco the dating of apatites of archaean rocks produced ages TF between 900 and 500 Ma, reflecting the progressive acting of the Brazilian margin mobile belts in the archaean craton areas. Apatite of some igneous and metamorphic rocks of the Braziliana age, in the Faixa Ribeira segment, between the Rio de Janeiro and Salvador cities, produced TF ages between 140 and 80 Ma. The basaltic and alkaline volcanism related to the Atlantic Ocean opening dated from this interval. The TF dating in apatites of the continental margin rocks allowed to date the event. In the Cabo Frio region (Southeastern part of Rio de Janeiro State), titanite and apatite of the Transamazonic orthognaisses produced TF dates between 190 and 80 to 40 Ma. The age around 190 Ma date previously the rift formation precursor of the South Atlantic Ocean opening, while the ages between 80 and 40 Ma were related to the alkaline rocks intrusion. The examples mentioned demonstrate the event diversity which may be dated by the Fission Tracks method, mainly in the craton area and margin belts study

Obsidian ages from Ecuador by the fission track dating

International Nuclear Information System (INIS)

Osorio, A.M.; Hadler, J.C.; Bigazzi, G.; Norelli, P.; Coltelli, M.; Salazar, E.

1991-01-01

Fission track dating was applied in order to study obsidian samples originated from Mullumica and Callejones flows, Oyacachi, Ecuador. Preliminary data show that the ratio between the mean diameter os spontaneous and induced tracks is about 0.9, an indication that the analysed samples were submitted to small fading during their geological histories. Ages were obtained around 0.2 x 10 6 a, in agreement with Miller and Wagners's results. Ages ranging from 0.17 x 10 6 a up to 0.23 x 10 6 a were obtained correcting the apparent ages by means of the plateau method. (author)

Studies of isothermal annealing of fission fragment and alpha particle tracks in Cr-39 polymer detectors

International Nuclear Information System (INIS)

Zaky, M.F.; Youssef, A.A.

2002-01-01

Two groups of CR-39 detectors samples are exposed to two types of charged particle radiation. The first group are severe damaged with fission fragment tracks from 2 52C f source. The second accepted alpha particles resulting from the interaction of highly energetic 1 9F -ions and a copper disk with thickness 1 cm, which are of less damage tracks than fission fragments. , The isothermal annealing of tracks in the temperature range from 175 to 300 degree C in step 25 degree C for annealing time of 10,15,20,25 and 30 minutes has been investigated. The changes introduced in the track density and track diameter for two types of irradiation in the detector have been observed and compared between them. The results indicate that the track density and the size of the tracks are considerably changed due to annealing

Development of the fission fragment track registration technique for the determination of the uranium contamination

International Nuclear Information System (INIS)

Tanaka, E.M.

1979-01-01

The Fission Fragment Track Registration Technique is developed to measure the uranium concentration about microgram of uranium per litre of liquid samples. The drying method of drops on the detector (Makrofol KG) and a special sampling procedure to avoid the cumbersome high density of tracks formation at the edge of the deposition surface as a 'ring' is adopted. The samples are irradiated by neutrons produced by the IEA-R1 Reactor (thermal neutron flux about 10 12 neutrons/cm 2 .s) inducing the uranium fission. The tracks registered by the fission fragments in the detector are chemically enlarged and counted by an automatic couting system. By this method the uranium concentrations ranging from 0,9 to 7,6 microgram of uranium per litre, can be determined with precisions between 2,7% the greater and 23% to the lower concentration. The uranium concentration measurements in human hair and urine are made showing that this method is very useful to control and detect eventual uranium contamination [pt

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

Thorium content of a mineral ore from Morro do Ferro by fission track technique

International Nuclear Information System (INIS)

Oliveira, C.A.N. de.

1980-10-01

The feasibility to determine thorium concentrations by fission track technique in samples of mineral ore has been demonstrated. The literature registers only the application of the fission track technique to mineral ore in the case where the fissionable element is uranium. The technique was applied to determine the thorium concentration of an ore sample from Morro do Ferro, taking advantage of the high thorium to uranium ratio in that mineral. The sample analysed presented a thorium concentration of 2467 +- 400 mg Th/Kg ore. The so called wet method was adopted by using the Bayer made Makrofol KG 10μm thick, as the detector foil, immersed in the thorium solution. The technique is also useful to determine thorium concentrations in environmental samples because of the following aspects: high sensitivity; fast chemical separation of interfering elements; low cost; and operational simplicity. (Author) [pt

On the fission track dating and annealing behaviour of accessory minerals of Eastern Ghats (Andhra Pradesh, India)

International Nuclear Information System (INIS)

Koul, S.L.

1978-01-01

Use of the etching of fission fragment damage tracks for an estimation of the uranium content of apatite and zircon crystals is described. The etching conditions have been studied for which visible tracks are developed. Fission track determined ages of 25 samples of apatite and zircon crystals from four widely separated regions of India; the Borra mines (Vishakapatanam), Kashipatnam (Vishakapatnam), the Khamam area (Andhra Pradesh) and the Kodrama mines (Bihar) have been determined. Mean ages for these regions are 456 +- 5, 389 +- 4, 486 +- 7 and 664 +- 7 million years respectively. It is concluded that the fission track ages of the minerals date the last metamorphic event of the Eastern Ghats, known as the Indian Ocean Cycle. Annealing studies confirm that radiation damaged fossil tracks can be erased in minerals under intense metamorphic episodes, thus resetting the geological clock. Extrapolation of the experimentally determined temperatures for annealing suggest that a temperature of 170 0 C in 10 6 years will erase all the tracks in the apatite mineral. The uranium concentration has been estimated to be approximately 10 -8 gm/gm in apatite and approximately 10 -6 gm/gm in zircon. (Auth.)

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...

Determination in soils of soluble uranium fraction in acid medium by fission tracks registration techniques

International Nuclear Information System (INIS)

Fernandes, G.P.

1980-01-01

The fission tracks registration technique was used to determine the concentration of uranium in soil solutions. The Makrofol KG, a synthetic plastic manufactured by Bayer, was used as a detector and the wet method was applied. The method was applied to a few samples of soils from Pocos de Caldas, Minas Gerais in Brazil. The concentrations of uranium in the samples and residues were also determined by other methods to compare the results obtained; only one sample showed deviation among the results obtained by the fission tracks method. (author)

Fission track dating and estimation of uranium in some garnets of Rajasthan (India)

Energy Technology Data Exchange (ETDEWEB)

Singh, S; Virk, H S [Punjabi Univ., Patiala (India). Dept. of Physics

1978-09-01

The experimental procedure, involving the preparation, etching, thermal neutron irradiation and scanning of the garnet samples, is described. The calculated fission track ages and uranium concentration are tabulated.

Estimation of trace levels of plutonium in urine samples by fission track technique

International Nuclear Information System (INIS)

Sawant, P.D.; Prabhu, S.; Pendharkar, K.A.; Kalsi, P.C.

2009-01-01

Individual monitoring of radiation workers handling Pu in various nuclear installations requires the detection of trace levels of plutonium in bioassay samples. It is necessary to develop methods that can detect urinary excretion of Pu in fraction of mBq range. Therefore, a sensitive method such as fission track analysis has been developed for the measurement of trace levels of Pu in bioassay samples. In this technique, chemically separated plutonium from the sample and a Pu standard were electrodeposited on planchettes and covered with Lexan solid state nuclear track detector (SSNTD) and irradiated with thermal neutrons in APSARA reactor of Bhabha Atomic Research Centre, India. The fission track densities in the Lexan films of the sample and the standard were used to calculate the amount of Pu in the sample. The minimum amount of Pu that can be analyzed by this method using doubly distilled electronic grade (E. G.) reagents is about 12 μBq/L. (author)

Fission track dating and thermal history of Habahe rock body in Altai

International Nuclear Information System (INIS)

Liu Shunsheng; Tan Kaixuan

2002-01-01

The fission track ages (FTA) of several apatite and zircon samples from Habahe rock body in Altai were determined. The FTA of apatites were 51.1-76.9 Ma, and FTA of zircons were 141-149 Ma. Modelling of the palaeo-temperature evolution [T(t)-path] of rock body relies on confined track length measurements and the annealing equations of Laslett et al. (1987). The thermal and uplift history of this region was discussed

Liquid nitrogen enhancement of partially annealed fission tracks in glass; and reply

International Nuclear Information System (INIS)

Wagner, G.A.; Carpenter, B.S.; Pilione, L.J.; Gold, D.P.

1977-01-01

Pilione and Gold (Nature 262: 773 (1976)) stated that it was possible to reveal partially annealed fission tracks in glass by immersion in liquid N 2 , and that it was possible to increase the total number of etchable tracks by increasing the immersion time. The present authors attempted to duplicate the work of the former authors using the same glass. They found no significant change in the number of etchable tracks after immersion in liquid N 2 , and they concluded that the latter has no effect on annealed tracks in glass. Any observed enhancement of partially annealed tracks is probably a surface effect and has no effect on the interior matrix of the glass. A reply by Pilione and Gold is appended. (U.K.)

Study on the technical feasibility of Fission-Track dating at two irradiation positions of the RA-6 research reactor

International Nuclear Information System (INIS)

Dorval, Eric

2005-01-01

The method of Fission-Track dating is based upon the detection of the damage caused by fission fragments from the Uranium contained in geological samples.In order to determine the age of a sample, both the amount of spontaneous fissions occurred and the Uranium concentration must be known.The latter requires the irradiation of the samples inside a reactor with a well-thermalized flux, so that fissions are induced over 235 U targets only. Therefore, the Uranium concentration may be determined.The main inconvenient presented by the irradiation sites at the RA-6 MTR-type reactor is that neutron flux is not completely thermal there, which means that fissions due to epithermal and fast neutrons will not be negligible.In the same way, tracks due to fissions of 238 U and 232 Th will be detected. In order to know the corrections that must be applied to those measurements performed in this reactor, it is necessary to characterize fast flux.Because of it, this laboratory's gamma spectrometry equipment had to be calibrated. After that, several activation detectors were irradiated and results were analyzed. Finally, it was determined that it is feasible to Fission-Track date at the I6 position. However, limitations associated to this method were analyzed for the values of flux measured in the different sites

Estimation of U content in coffee samples by fission-track counting

International Nuclear Information System (INIS)

Sharma, P.K.; Lal, N.; Nagpaul, K.K.

1985-01-01

Because coffee is consumed in large quantities by humans, the authors undertook the study of the uranium content of coffee as a continuation of earlier work to estimate the U content of foodstuffs. Since literature on this subject is scarce, they decided to use the well-established fission-track-counting technique to determine the U content of coffee

Detection of fission fragments using thick samples in contact with solid state nuclear track detectors

International Nuclear Information System (INIS)

Lima, D.A. de; Martins, J.B.; Tavares, O.A.P.

1987-01-01

Whenever use is made of thick samples in contact with solid state nuclear track detectors for determining fission yields, one of the fundamental problems is the evaluation of the effective number of target nuclei which contributes to the fraction of the number of fission events that will be recorded. The evaluation of the effective number of target nuclei which contributes to recorded events is based on the effective thickness of the sample. A method for evaluating effective thickness of thick samples for binary fission modes, is presented. A cross section equation which takes into account all the necessary corrections due to fragment attenuation effects by a thick target for calculation induced fission yields, was obtained. (Author) [pt

LENMODEL: A forward model for calculating length distributions and fission-track ages in apatite

Science.gov (United States)

Crowley, Kevin D.

1993-05-01

The program LENMODEL is a forward model for annealing of fission tracks in apatite. It provides estimates of the track-length distribution, fission-track age, and areal track density for any user-supplied thermal history. The program approximates the thermal history, in which temperature is represented as a continuous function of time, by a series of isothermal steps of various durations. Equations describing the production of tracks as a function of time and annealing of tracks as a function of time and temperature are solved for each step. The step calculations are summed to obtain estimates for the entire thermal history. Computational efficiency is maximized by performing the step calculations backwards in model time. The program incorporates an intuitive and easy-to-use graphical interface. Thermal history is input to the program using a mouse. Model options are specified by selecting context-sensitive commands from a bar menu. The program allows for considerable selection of equations and parameters used in the calculations. The program was written for PC-compatible computers running DOS TM 3.0 and above (and Windows TM 3.0 or above) with VGA or SVGA graphics and a Microsoft TM-compatible mouse. Single copies of a runtime version of the program are available from the author by written request as explained in the last section of this paper.

Dating by fission tracks in archaeology. 2. Characterization and dating of obsidian artefact

International Nuclear Information System (INIS)

Poupeau, G.; Zuleta, E.

1984-01-01

The ways of obsidian characterization presently used in archaeology are presented. The possibilities of the fission track method are more specially discussed, with two examples of works done in Japan and on any samples of andine America. (L.C.) [pt

Sequential fission process observed in the reaction (16.7 MeV/u) 238U + nat.Au using mica as dielectric track detector

International Nuclear Information System (INIS)

Shahzad, Muhammad Ikram; Qureshi, Imtinan Elahi; Manzoor, Shahid; Khan, Hameed Ahmed

1999-01-01

The evidence of sequential fission has been found in the heavy-ion reaction (16.7 MeV/u) 238 U + nat. Au, using muscovite mica as Dielectric Track Detector (DTD) placed in a 2π-geometry configuration. The reaction products originating from the interactions of 238 U ions with the atoms of gold were registered in the detector in the form of tracks and identified for performing a detailed kinematical analysis. For this purpose the spherical polar coordinates of the correlated tracks of the multipronged events have been analyzed on an event-by-event basis. Automatic, semi-automatic and manual measuring methods have been employed to collect and manipulate the track data. The known characteristics of binary and ternary events observed in the reaction have been used for the calibration of the detectors. The computed masses, Q-values and relative velocities of the reaction products determined in this analysis are compared with theoretical predictions based on sequential fission process. Agreement within one standard deviation with respect to the experimental values has been found for the majority of analyzed events. Therefore, it is concluded that three particles in the exit channel of the reaction are produced in two successive steps. In the first step of the reaction, two intermediate nuclei are formed as a result of an inelastic collision between projectile and target atoms while in the second step the fission of one of the intermediate nuclei of the previous step takes place. Furthermore no proximity effects have been observed

Measurement of uranium in human teeth and kidney stones with the fission track technique

International Nuclear Information System (INIS)

Vartanian, R.

1986-01-01

The measurement of uranium in human teeth and in kidney stones was carried out using the fission track activation technique. In this determination 2759 and 2205 absolute counts of tracks for teeth samples and 1689 tracks for kidney stone samples were performed, respectively. The results are as follows: xsub(tooth) (1)=(0.227+-0.006) ppm, xsub(tooth) (2)=(0.143+-0.007) ppm and xsub(kidney)=(0.568+-0.020) ppm. The experimental method is described and the results are discussed. (author)

A fission track technique used for hydrogeochemical prospecting in Northern India

International Nuclear Information System (INIS)

Singh, N.P.; Singh, S.; Virk, H.S.

1988-01-01

A fission track technique is employed to determine the uranium content of water samples collected from different locations of the middle and outer Himalayas. The regional threshold for the uranium content is determined for water samples of different areas. The identification of anomalies in an area of uranium mineralization confirmed that the hydrogeochemical technique could successfully be used for uranium exploration. (author)

Absolute measurement of thermal neutron fluence and its application for fission track dating

International Nuclear Information System (INIS)

Ganzawa, Yoshihiro; Honda, Teruyuki; Nozaki, Tetsuya.

1988-01-01

The absolute measurements of thermal neutron fluence for fission track dating have been developed after the proceeding results of Honda et al. (1987). The 2,200 m/sec activation cross section of 197 Au (98.8 barn) is corrected to 87.4 barn (σa) by the three factors of the neutron temperature, Maxwellian distribution of thermal neutrons and non 1/v correction factor for the above absolute measurement. The calibrated factor (B th ) of standard glasses (SRM613, SRM962a, CN-1 and CN-2) and zeta-a (ζa) values for fission track dating are determined on the basis of these experimental results. The values of B th , (7.47 ± 0.29) x 10 9 for SRM613, (7.43 ± 0.34) x 10 9 for SRM962a, (2.50 ± 0.06) x 10 9 for CN-1 and (2.74 ± 0.06) x 10 9 for CN-2 closely agree with those reported previously by Honda et al. (1987). Further, the ζa values of 392.3 ± 16.5 for SRM962a and SRM613, 131.4 ± 3.1 for CN-1 and 144.1 ± 3.3 for CN-2 calculated from B th , effective thermal neutron fission cross-section σf (497.4 barn), isotopic abundance ratio 235 U/ 239 U, I (7.2527 x 10 -3 ) and spontaneous fission decay constant of 238 U, λ f (6.85 x 10 -17 a -7 ) show close agreement with ζ b values (392.5 ± 10.0, 131.6 ± 3.3, 140.1 ± 3.5) derived from the absolute age of Fish Canyon Tuff (27.9 ± 0.7 Ma) respectively. The fission track dating of zircons separated from Oligocene-Miocene tuff distributed in Eastern Hokkaido have been carried out by the external detector method using ζ a . The obtained ages are 28.6 ± 0.7 Ma (1 - 2) and 23.3 ± 0.7 Ma (3 - 2). These results agree well with the geologic age supported from Ashoro Fossil Fauna, K-Ar ages of volcanic rocks and stratigraphy in this area. (author)

Comparison through fission-track analysis of portions of Australia and Antarctica adjacent prior to continental drift

International Nuclear Information System (INIS)

Stump, E.; Fitzgerald, P.G.

1990-01-01

Australia and Antarctica have been reconstructed by the matching of three terranes in western Victoria with three terranes in northern Victoria Land. Apparent fission-track ages from granitic rocks of these matched regions are compared. In western Victoria, Australia, data reflect a history of slow cooling following intrusion in early to middle Paleozoic time. In northern Victoria Land, Antarctica, a complex history of cooling and uplift is indicated, with uplift of the present-day mountains commencing approximately 50 Ma. Fission tracks in apatites from most samples from northern Victoria Land were completely re-set to zero by the thermal effects of Jurassic tholeiitic magmatism. Apatite in three samples however, predate the Jurassic and were only partially re-set by this event. Apparent sphene fission-track ages indicate that the three terranes in northern Victoria Land have shared a common thermal history since the Devonian. With the exception of one small area in western Victoria, neither western Victoria nor northern Victoria Land data show a clear influence of rifting and breakup in the late Cretaceous. Overall, the data indicate that once the breakup of Australia and Antarctica had occurred, their thermal and tectonic histories evolved independently along differing paths. (author)

Fission track ages on apatite of Bergell rocks from central Alps and Bergell boulders in Oligocene sediments

International Nuclear Information System (INIS)

Wagner, G.A.; Miller, D.S.

1979-01-01

Previous radiometric dating studies indicated that the Bergell region, in contrast to other regions of the Central Alps, experienced an early, rapid uplift, but with decreasing rate. Furthermore, there is also a geological record of the early uplift history of the Bergell granite by the existence of boulders which were derived from this granite and which occur in the Late Oligocene sediments of the Po plain. In this work the uplift history of the Bergell is studied in more detail by fission track dating of additional apatites from the Bergell region. Secondly, by determining apatite fission track ages the granitic boulders of the Po plain can be re-assigned to their original vertical position within the Bergell intrusive before erosion removed them in Late Oligocene time. A rather conservative estimate replaces them 6 km above the present morphology of the Bergell massif. Thus, the thickness of the Bergell granite must have been at least 8 km. Generally, fission track studies on boulders may become an important tool to study the vertical extent of mountain chains during the geological past. (Auth.)

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.

Thermal annealing of fission tracks in fluorapatite, chlorapatite, manganoanapatite, and Durango apatite: experimental results

International Nuclear Information System (INIS)

Ravenhurst, C.E.; Roden-Tice, M.K.; Miller, D.S.

2003-01-01

It is well known that the optically measured lengths of fission tracks in apatite crystals are a function of etching conditions, crystallographic orientation of the track, composition of the crystal, and the state of thermal annealing. In this study we standardize etching conditions and optimize track length measurability by etching until etch pits formed at the surface of each apatite crystal reached widths of about 0.74 μm. Etching times using 5M HNO 3 at 21 o C were 31 s for Otter Lake, Quebec, fluorapatite; 47 s for Durango, Mexico, apatite; 33 s for Portland, Connecticut, manganoanapatite; and 11 s for Bamle, Norway, chlorapatite. An etching experiment using two etchant strengths (5M and 1.6M HNO 3 ) revealed that, despite significant differences in etch pit shape, fission-track length anisotropy with respect to crystallographic orientation of the tracks is not a chemical etching effect. A series of 227 constant-temperature annealing experiments were carried out on nuclear reactor induced tracks in oriented slices of the apatites. After etching, crystallographic orientations of tracks were measured along with their lengths. The 200-300 track lengths measured for each slice were ellipse-fitted to give the major (c crystallographic direction) and minor (a crystallographic direction) semi-axes used to calculate equivalent isotropic lengths. The equivalent isotropic length is more useful than mean length for thermal history analysis because the variation caused by anisotropy has been removed. Using normalized etching procedures and equivalent isotropic length data, we found that the fluorapatite anneals most readily, followed by Durango apatite, manganoanapatite, and lastly chlorapatite. (author)

Apatite fission-track dating of erosion in the eastern Andes, Bolivia

International Nuclear Information System (INIS)

Crough, S.T.

1983-01-01

Three samples from a Triassic-age batholith in the eastern Andes northeast of La Paz, Bolivia yield apatitic fission-track ages of 11-13 Ma. Interpreting these young ages as due to uplift and erosion requires approximately 2.5-5.0 km of erosion in the past 12 Ma, an amount which is consistent with the known geology and which is typical of many active mountain ranges. (orig.)

Liquid nitrogen enhancement of partially annealed fission tracks in glass

International Nuclear Information System (INIS)

Pilione, L.J.; Gold, D.P.

1976-01-01

It is known that the number density of fission tracks in solids is reduced if the sample is heated before chemical etching, and the effect of annealing must be allowed for before an age can be assigned to the sample. The extent of annealing can be determined by measuring the reduction of track parameters (diameter and/or length) and comparison with unannealed tracks. Correct ages can be obtained by careful calibration studies of track density reduction against track diameter or length reduction at different annealing temperatures and times. For crystallised minerals, however, the resulting correction techniques are not generally valid. In the experimental work described glass samples were partially annealed and then immersed in liquid N 2 for various periods, and it was shown that the properties of the glass and the track parameters could be altered so as to observe tracks that would normally be erased by annealing. The results of track density measurements against liquid N 2 immersion times are shown graphically. A gain of about 40% was achieved after 760 hours immersion time. The size of the tracks was not noticeably affected by the immersion. It was thought that thermal shock might be the cause of the track enhancement, but it was found that repeated immersion for about 2 hours did not lead to an increase in track density. Other studies suggest that the mechanism that erases the tracks through annealing may be partially reversed when the temperature of the sample is significantly lowered for a sufficient length of time. Further work is under way to find whether or not the process of enhancement is a reversal of the annealing process. Similar enhancement effects using liquid N 2 have been observed for d-particle tracks in polycarbonate detectors. (U.K.)

Convection methodology for fission track annealing: direct and inverse numerical simulations in the multi-exponential case

International Nuclear Information System (INIS)

Miellou, J.C.; Igli, H.; Grivet, M.; Rebetez, M.; Chambaudet, A.

1994-01-01

In minerals, the uranium fission tracks are sensitive to temperature and time. The consequence is that the etchable lengths are reduced. To simulate the phenomenon, at the last International Conference on Nuclear Tracks in solids at Beijing in 1992, we proposed a convection model for fission track annealing based on a reaction situation associated with only one activation energy. Moreover a simple inverse method based on the resolution of an ordinary differential equation was described, making it possible to retrace the thermal history in this mono-exponential situation. The aim of this paper is to consider a more involved class of models including multi-exponentials associated with several activation energies. We shall describe in this framework the modelling of the direct phenomenon and the resolution of the inverse problem. Results of numerical simulations and comparison with the mono-exponential case will be presented. 5 refs. (author)

Sequential fission process observed in the reaction (16.7 MeV/u) {sup 238}U + {sup nat.}Au using mica as dielectric track detector

Energy Technology Data Exchange (ETDEWEB)

Shahzad, Muhammad Ikram; Qureshi, Imtinan Elahi; Manzoor, Shahid; Khan, Hameed Ahmed

1999-01-04

The evidence of sequential fission has been found in the heavy-ion reaction (16.7 MeV/u) {sup 238}U + {sup nat.}Au, using muscovite mica as Dielectric Track Detector (DTD) placed in a 2{pi}-geometry configuration. The reaction products originating from the interactions of {sup 238}U ions with the atoms of gold were registered in the detector in the form of tracks and identified for performing a detailed kinematical analysis. For this purpose the spherical polar coordinates of the correlated tracks of the multipronged events have been analyzed on an event-by-event basis. Automatic, semi-automatic and manual measuring methods have been employed to collect and manipulate the track data. The known characteristics of binary and ternary events observed in the reaction have been used for the calibration of the detectors. The computed masses, Q-values and relative velocities of the reaction products determined in this analysis are compared with theoretical predictions based on sequential fission process. Agreement within one standard deviation with respect to the experimental values has been found for the majority of analyzed events. Therefore, it is concluded that three particles in the exit channel of the reaction are produced in two successive steps. In the first step of the reaction, two intermediate nuclei are formed as a result of an inelastic collision between projectile and target atoms while in the second step the fission of one of the intermediate nuclei of the previous step takes place. Furthermore no proximity effects have been observed.

An early cretaceous phase of accelerated erosion on the south-western margin of Africa: evidence from apatite fission track analysis and the offshore sedimentary record

International Nuclear Information System (INIS)

Brown, R.W.; Gleadow, A.J.W.; Rust, D.J.; Summerfield, M.A.; De Wit, M.C.J.

1990-01-01

Apatite fission track ages and confined track length distributions have been determined for rock samples from the south-western continental margin of Africa. The apatite ages fall into two groups, one having early Cretaceous ages and mean confined track lengths of ∼ 14 μm with very few short tracks, and the other having older ages with confined track length distributions containing a significant proportion of strongly annealed tracks (<10 μm). In any particular area the older apatite ages only occur above a critical threshold elevation, forming a regional pattern in the data and indicating cooling of the upper few kilometres of the crust during the early cretaceous. This episode of cooling is shown to have been the consequence of an accelerated phase of erosion associated with the early stages of rifting and break-up of Gondwana, and correlates with sedimentation patterns derived from borehole data for the adjacent offshore basin. (author)

An early cretaceous phase of accelerated erosion on the south-western margin of Africa: evidence from apatite fission track analysis and the offshore sedimentary record

Energy Technology Data Exchange (ETDEWEB)

Brown, R.W.; Gleadow, A.J.W. (La Trobe Univ., Bundoora (Australia)); Rust, D.J.; Summerfield, M.A. (Edinburgh Univ. (UK)); De Wit, M.C.J. (De Beers Consolidated Mines Ltd., Kimberley (South Africa))

1990-01-01

Apatite fission track ages and confined track length distributions have been determined for rock samples from the south-western continental margin of Africa. The apatite ages fall into two groups, one having early Cretaceous ages and mean confined track lengths of {approx} 14 {mu}m with very few short tracks, and the other having older ages with confined track length distributions containing a significant proportion of strongly annealed tracks (<10 {mu}m). In any particular area the older apatite ages only occur above a critical threshold elevation, forming a regional pattern in the data and indicating cooling of the upper few kilometres of the crust during the early cretaceous. This episode of cooling is shown to have been the consequence of an accelerated phase of erosion associated with the early stages of rifting and break-up of Gondwana, and correlates with sedimentation patterns derived from borehole data for the adjacent offshore basin. (author).

Superheavy-element fission tracks in iron meteorites, and reply by Bull, R.K

International Nuclear Information System (INIS)

Runcorn, S.K.

1980-01-01

Comment is made on the lack of superheavy element (SHE) fission tracks observed in silicates from the class IA Odessa iron meteorite by Bull (Nature; 282:393 (1979)). Two explanations are suggested. Firstly, a thermal history for Odessa can be constructed in which the meteorite reaches track retention temperatures only after a time corresponding to many half lives for the SHEs (taken to be approximately 100 Myr) has elapsed and secondly that the IA irons never took up many SHEs. These suggestions are discussed in a reply by Bull. (U.K.)

The thermal evolution and timing of hydrocarbon generation in the Maritimes Basin of eastern Canada: evidence from apatite fission track data

International Nuclear Information System (INIS)

Grist, A.M.; Zentilli, M.

1995-01-01

Sandstone drill core and/or cuttings from six wells in the Gulf of St. Lawrence and cabot Strait have been analyzed using the apatite fission track (AFT) method. Measured AFT ages for the late Paleozoic sandstones range from 26 ±7 to 184 ±28 Ma (2-σ errors). The AFT data indicate that most Maritimes Basin strata were heated to temperatures in excess of 100-150 o C very soon after their deposition. The strata also attained significant vitrinite reflectance (R 0 ) levels (i.e., reaching the oil window) early in the burial history. These findings imply the generation of hydrocarbons and coalbed methane in the early basin history (pre-250 Ma). In the Maritimes Basin AFT and R 0 data provide complementary information about the integrated thermal history, including maximum burial temperatures (from R 0 data), and information on the subsequent cooling history from AFT analysis. The present study also supports the proposal made previously by others that substantial erosion of the Eastern Canadian margin (up to 4 km) has occurred since the Permian and extends the AFT evidence for this erosional event to include the southern Gulf of St. Lawrence area. Thermal models of the AFT data demonstrate that they are consistent with a history of exhumation of basin strata since late Permian time. The model-predicted AFT age and track length histograms closely correspond to the measured AFT parameters. AFT analysis also indicates present-day geothermal gradients of less than 40 o C/km. (author). 42 refs.,3 tabs., 7 figs

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.

International Union of Geological Sciences Subcommission on Geochronology recommendation for the standardization of fission track dating calibration and data reporting

International Nuclear Information System (INIS)

Hurford, A.J.

1990-01-01

Because of the difficulties of calibration in fission track (FT) dating over the last 20 yr, including uncertainty of the absolute λ f value, complexities of neutron dosimetry, complexities of neutron irradiation, correction factors necessary in some methodological procedures, and personal factors in track counting, the Working Group elected at the Cambridge ICOG meeting in 1986 recommended to FT workers meeting at the 6th International Fission Track Dating Workshop in Besancon on 9 September 1988, a uniform approach to system calibration, sample irradiation, calculation of FT age, and presentation of data. After discussion and modification, the recommendation was accepted. This modified recommendation is presented. (author)

The Comparison Study of Neutron Activation Analysis and Fission Track Technique for Uranium Determination

International Nuclear Information System (INIS)

Sirinuntavid, Alice; Rodthongkom, Chouvana

2007-08-01

Full text: Comparison between Neutron Activation Analysis (NAA) and fission track technique for uranium determination in solid samples was studied by use of standard reference materials, i.e., ore, coal fly ash, soil. For NAA, the epithermal neutron was applied for activated irradiation. Then, the 74.5 keV gamma from U-239 or 277.7 keV gamma from Np-239 was measured. For high Uranium content samples, NAA method with 74.5 keV gamma measurement, gave higher precision result than the 277.7 keV gamma measurement method. NAA method with 277.7 keV gamma measurement, gave higher sensitivity and precision result for low Uranium content samples and the uranium contained less than 10 ppm samples. Nevertheless, the latter procedure needed longer time for neutron irradiation and analysis procedure. In comparison the results of Uranium analysis between NAA and fission track, it was found that no significant difference within 95 % of confidence level

Understanding the uplift pattern in Mesozoic and Cenozoic,, eastern Dabie area, China using fission track dating of apatite

International Nuclear Information System (INIS)

Wu Qianhong; Liu Shunsheng

2002-01-01

By using the fission track dating technique, a preliminary study was carried out on the fission track ages (FTA) of apatite, their distribution patterns and hints over the tectonics activities during Mesozoic and Cenozoic in the east Dabie area. Attempts were also made to improve the conventional statistical method for the tracks. Ranging from 59.4 +- 3.4 Ma to 105.6 +- 9.8 Ma, the FTA results of apatite spread in the wide range and increased rapidly from the east to the west area. Sine 95 Ma, the uplift rate has been quite slow and asymmetry. The FTA value in the middle area of Xiaotian-Mozitan Fault may imply its uplift in Cretaceous. The faulting should be the main control factor for the uplift of this area

Development of nuclear microfilters using the fission tracks registration technique

International Nuclear Information System (INIS)

Yamasaki, I.M.; Geraldo, L.P.

1990-10-01

Nuclear microfilters with mean pores diameter in the range from 1.9 to 10.6 μm have been produced using the fission tracks registration technique in Makrofol KG (8 μm thickness). Fluctuations around 11% and 10% were obtained respectively for the pores size and pores uniformity in the analysis of a typical sample of microfilter. The essential features of the microfilters were similar to those ones, commercially known as Nuclepore and thus they may be routinely employed in the several applications areas of the Industry and Biology. (author)

Fission track dating and uranium estimation in pegmatitic minerals of Rajasthan state (India)

Energy Technology Data Exchange (ETDEWEB)

Singh, S; Virk, H S [Punjabi Univ., Patiala (India). Dept. of Physics

1978-12-01

Fission track geochronology of muscovite samples collected from some pegmatitic mines of Bhilwara and Ajmer districts of Rajasthan state (India) has been discussed. The ages obtained suggest the occurrence of Delhi Orogenic Cycle as the last major metamorphic activity in the region. The atomic fraction of uranium in muscovite samples is less than 1 p.p.b.

Apatite fission track analysis: geological thermal history analysis based on a three-dimensional random process of linear radiation damage

International Nuclear Information System (INIS)

Galbraith, R.F.; Laslett, G.M.; Green, P.F.; Duddy, I.R.

1990-01-01

Spontaneous fission of uranium atoms over geological time creates a random process of linearly shaped features (fission tracks) inside an apatite crystal. The theoretical distributions associated with this process are governed by the elapsed time and temperature history, but other factors are also reflected in empirical measurements as consequences of sampling by plane section and chemical etching. These include geometrical biases leading to over-representation of long tracks, the shape and orientation of host features when sampling totally confined tracks, and 'gaps' in heavily annealed tracks. We study the estimation of geological parameters in the presence of these factors using measurements on both confined tracks and projected semi-tracks. Of particular interest is a history of sedimentation, uplift and erosion giving rise to a two-component mixture of tracks in which the parameters reflect the current temperature, the maximum temperature and the timing of uplift. A full likelihood analysis based on all measured densities, lengths and orientations is feasible, but because some geometrical biases and measurement limitations are only partly understood it seems preferable to use conditional likelihoods given numbers and orientations of confined tracks. (author)

Uranium fission track length distribution modelling for retracing chronothermometrical history of minerals

International Nuclear Information System (INIS)

Rebetez, M.

1987-01-01

Spontaneous fission of uranium 238 isotope contained in certain minerals creates damage zones called latent tracks, that can be etched chemically. The observation of these etched tracks and the measurement of their characteristics using an optical microscope are the basis of several applications in the domain of the earth sciences. First, the determination of their densities permits dating a mineral and establishing uranium mapping of rocks. Second, the measurement of their lengths can be a good source of information for retracing the thermal and tectonic history of the sample. The study of the partial annealing of tracks in apatite appears to be the ideal indicator for the evaluation of petroleum potential of a sedimentary basin. To allow the development of this application, it is necessary to devise a theoretical model of track length distributions. The model which is proposed takes into account the most realistic hypotheses concerning registration, etching and observation of tracks. The characteristics of surface tracks (projected lengths, depths, inclination angles, real lengths) and confined tracks (Track IN Track and Track IN Cleavage) are calculated. Surface tracks and confined tracks are perfectly complementary for chrono-thermometric interpretation of complex geological histories. The method is applied to the case of two samples with different tectonic history, issued from the cretaceous alcalin magmatism from the Pyrenees (Bilbao, Spain). A graphic method of distribution deconvolution is proposed. Finally, the uranium migration, depending on the hydrothermal alteration, is studied on the granite from Auriat (France) [fr

The spark counting of etched fission-fragment tracks in polycarbonate for a personal neutron dosimetry system

International Nuclear Information System (INIS)

Harrison, K.G.; Hancock, I.B.; Holt, P.D.; Wylie, J.W.

1977-10-01

A new type of personal neutron dosimeter, in which neutron-induced fissions in a thin 237 Np foil are detected by a polycarbonate track-detector, is under development at Harwell for use in a nuclear-fuel reprocessing plant. As part of the development programme, an experimental dosimeter, etching facility and spark counter have been used to study the spark-counting method for counting fission-fragment tracks in polycarbonate. Emphasis has been placed on developing operating procedures for the counter consistent with good overall reproducibility. Existing methods for the optimizing and testing of spark counters is briefly reviewed and a practical operational testing procedure is devised. The optimized system is found to be relatively foolproof in operation and gives good results in unskilled use as well as under carefully-controlled laboratory conditions. (author)

The potential of apatite fission track dating of vertical profiles in Namibia and the implications for passive margin evolution

International Nuclear Information System (INIS)

Raab, M.J.; Brown, R.W.; Cockburn, H.A.P.

1999-01-01

Full text: The on- and offshore geology of the Namibian passive continental margin has experienced kilometer scale erosion since South Atlantic opening in Lower Cretaceous times. A vertical apatite fission track profile of four samples in the Namibian highland has been analysed to constrain the low temperature thermal history of that area since the Pan-African Damara Orogeny at about 550 Ma. As a temperature sensitive thermochronological technique apatite fission track analysis is a powerful tool in constraining the low temperature history of rocks over a range of 60-110 deg C. These temperatures, depending on the geothermal gradient, equal a burial depth of 3-5 km so the method can reconstruct the cooling history of rocks as they approached the surface in response to erosion and tectonic processes. The four apparent apatite cooling ages are taken over a vertical distance of 300 m from the Windhoek Graben 40 km north of Windhoek. Forward modelling of the age and track length distribution has shown that these samples experienced high palaeotemperatures from ca. 90 to 95 deg C in the Late Cretaceous. This information was used to calculate the palaeogeothermal gradient at that time (20 deg C/km) which gives an estimate of the sedimentary cover of about 4.5 km which has been removed over a few million years in the Late Cretaceous. It was previously thought that the Namibian highland has been exposed at the surface more or less since the Permo-Carboniferous. In fact the samples provide evidence for a post Carboniferous reburial history of several kilometers followed by a short period of accelerated denudation in the Late Cretaceous at about 70 Ma. This might imply a far larger extent of the Etendeka flood basalts (132 Ma) and/or an underestimated sedimentary Karoo (Permian to Jurassic) thickness. The wider importance of these four data is that they detect the geomorphic impact of a global change of plate motion along the passive margin of Namibia which is known from a

A method for the measurement of fission rates in fast neutron fields using solid state track detectors

International Nuclear Information System (INIS)

Hansen, W.; Vogel, W.

1984-04-01

Solid state track detectors (SSTDs) are increasingly used for the registration of radiation in different fields of nuclear physics. Because of their small sizes and masses and the absence of any electronics during exposure SSTDs do not cause distortions in the system to be investigated and are useful for measurements at such places being difficult of access. The elaboration of a method is described for fission rate measurements in fast neutron fields applying SSTDs and different fissionable isotopes which were electrodeposited on stainless steel backings. Experiences of the electrodeposition and results of quality checks are presented. The evaluation of the etched tracks is performed with spark counter technique. The dependence of the counting result on essential influence parameters is discussed. (author)

Use of fission track for deciphering the dissolution mechanism of silicates glasses

International Nuclear Information System (INIS)

Petit, J.C.; Brousse, C.

1985-09-01

Polished sections of silicate glasses containing latent or pre-etched fission tracks have been subjected to corrosion in deionized water or NaCl brines at 20, 50 and 100 0 C. The evolution of glass surface helps deciphering among reported dissolution models. We show that ion-exchange is dominant in simple glasses while in complex ones, dissolution involves several steps including an in-situ transformation of the pristine material and a reprecipitation of dissolved species

Mass distribution of fission fragments using SSNTDs based image analysis system

International Nuclear Information System (INIS)

Kolekar, R.V.; Sharma, D.N.

2006-01-01

Lexan polycarbonate track detector was used to obtain mass distribution of fission fragments from 252 Cf planchette source, Normally, if the fission fragments are incident perpendicular to the lexan surface, the diameter of heavy fragment is greater than that of lighter fragment. In practical problems fission fragments are incident on the detector at all angles. So, in the present experiment, lexan detector was exposed to 252 Cf planchette source in 2π geometry. Fission fragments were incident on the detector with various angles. So the projected fission track length for fission fragment of same energy is different because of different angle of incidence. Image analysis software was used to measure the projected track length. But the problem is that for fission fragment having greater angle of incidence the entire track length is not focused on the surface. So reduced track length is measured. This problem is solved by taking two images, one at the surface and one at the tip of track and then overlapping both the images using image analysis software. The projected track length and the depth of the track were used to get the angle of incidence. Fission track lengths were measured for same angle of incidence. In all 500 track lengths were measured and plot for mass distribution for fission fragment was obtained.(author)

Identification of the source of manufacture of obsidian through the dating with the method of fission track

International Nuclear Information System (INIS)

Arias, C.; Bigazzi, G.; Bonadonna, F.P.; Radi, G.; Bernardes, C.; Hadler Neto, J.C.; Lattes, C.M.G.; Araya, A.M.O.; Oliveira, J.X.

1986-01-01

Identification of the source of manufacture of obsidian through the dating with the method of fission track. After a brief description of fission track dating method and of the problems related to its application to volcanic glasses, we show and discuss data about obsidians of geological origin from Mediterranean basin and Latin America and of archaeological origin found in prehistoric sites from Italian peninsula. The analysis of the results shows the excellent performance of fission track method to identify the provenance of obsidians of archaeological origin, provided important constributions both from the methodological pointo of view-excellent agreement between the two correction techniques of apparent ages, size-correction technique and plateau age -, as from the archaeological point of view - we could identify four possible sources of provenance in Italy, the obsidian from Monte Arci, Sardinia, the obsidian from Pahnarola island, the obsidian from Gabelloto, Lipari island and the obsidian from Balata dei Turchi, Pantelleria island; and it ca be shown that Lipari obsidian began to be used at a very antique phase of neolithic period. The data about Latin American samples, though fragmented, constitute in an inicial study promissing perpectives as it can be observed by the comparisions made with the data published by others authors about geologic and archaeologic samples from the same area. (Author) [pt

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

Evidence for bimodal fission in the heaviest elements

International Nuclear Information System (INIS)

Hulet, E.K.; Wild, J.F.; Lougheed, R.W.

1987-08-01

We have measured the mass and kinetic-energy partitioning in the spontaneous fission of five heavy nuclides: 258 Fm, 259 Md, 260 Md 258 No, and 260 [104]. Each was produced by heavy-ion reactions with either 248 Cm, 249 Bk, or 254 Es targets. Energies of correlated fragments from the isotopes with millisecond half lives, 258 No and 260 [104], were measured on-line by a special rotating-wheel instrument, while the others were determined off-line after mass separation. All fissioned with mass distributions that were symmetric. Total-kinetic-energy distributions peaked near either 200 or 235 MeV. Surprisingly, because only a single Gaussian energy distribution had been observed previously in actinide fission, these energy distributions were skewed upward or downward from the peak in each case, except for 260 [104], indicating a composite of two energy distributions. We were able to fit accurately two Gaussian curves to the gross energy distributions from the four remaining nuclides. From the multiple TKE distributions and the shapes of the mass distributions, we conclude that there is a low-energy fission component with liquid-drop characteristics which is admixed with a much higher-energy component due to closed fragment shells. We now have further evidence for this conclusion from measurements of the neutron multiplicity in the spontaneous fission of 260 Md. 25 refs., 9 figs

Dating of zircons by the fission track method

International Nuclear Information System (INIS)

Tenorio Hernandez, L.M.

1992-01-01

This work describes the methodology to date zircons by the Fission Track Method. A brief discussion is made of the physical principles of the method, physical properties of zircons and the geochemical properties of uranium. When starting with a hand sample, a mineral separation is required; to do this the following steps are needed: crushing and sieving of the sample, washing and drying, magnetic separation, heavy liquid separation (Bromoform 2.89 g/cm 3 , Diyodomethane = 3.31 g/cm 3 ), and manual separation on a stereoscopic microscope. Once the zircon concentrate is obtained, these are mounted on a FEP teflon mount, then polished and etched on an eutectic mix of 10 g. of KOH + 7.2 g. of NaOH, heated to 210 Centigrade degrees. Afterwards the mounts are prepared for irradiation, sterilizing and putting on top of them an external detector (a thin sheet of muscovite poor in uranium content). The package is then wrapped in plastic and sent to the reactor together with standard zircons of known age (Fish Canyon Tuff: Naeser et.al., 1981), mounted in the same way, plus standard glasses of known uranium content. The package was irradiated in a site known as SIRCA (Rotatory Capsules Irradiation System). Then the package is left to decay for several days, and then the external detectors are etched in a 48% concentrated hydrofluoric acid for 5 minutes. Once the samples are processed through the mentioned steps, spontaneous tracks appear in the zircons and induced tracks appear in the external detectors. On counting the tracks one obtains ρ s (spontaneous track density) and ρ 1 (induced track density). These two parameters together with another one called '#zeta #' (obtained from the standard zircons and glasses), are used to obtain the age of the sample. Zircons from Cerro de Mercado, Durango were dated and the age obtained was 30 ±5 Ma. This date is in agreement with similar results obtained by Fleisher and Naeser (1975) for zircons of the same locality and dated by the

Application of fission track detectors to californium-252 neutron dosimetry in tissue near the radiation source

International Nuclear Information System (INIS)

Oswald, R.A.; Lanzl, L.H.; Rozenfeld, M.

1981-01-01

Fission track detectors were applied to a unique problem in neutron dosimetry. Measurements of neutron doses were required at locations within a tumor of 1 cm diameter implanted on the back of a mouse and surrounded by a square array of four 252 Cf medical sources. Measurements made in a tissue-equivalent mouse phantom showed that the neutron dose rate to the center of the tumor was 2.18 rads mg -1 h -1 +- 8.4%. The spatial variation of neutron dose to the tumor ranged from 1.88 to 2.55 rads mg -1 h -1 . These measurements agree with calculated values of neutron dose to those locations in the phantom. Fission track detectors have been found to be a reliable tool for neutron dosimetry for geometries in which one wishes to know neutron dose values which may vary considerably over distances of 1 cm or less

Application of fission track detectors to californium-252 neutron dosimetry in tissue near the radiation source

International Nuclear Information System (INIS)

Oswald, R.A.; Lanzl, L.H.; Rozenfeld, M.

1981-01-01

Fission track detectors were applied to a unique problem in neutron dosimetry. Measurements of neutron doses were required at locations within a tumor of 1 cm diameter implanted on the back of a mouse and surrounded by a square array of four 252 Cf medical sources. Measurements made in a tissue-equivalent mouse phantom showed that the neutron dose rate to the center of the tumor was 2.18 rads micrograms-1 h-1 +/- 8.4%. The spatial variation of neutron dose to the tumor ranged from 1.88 to 2.55 rads micrograms-1 h-1. These measurements agree with calculated values of neutron dose to those locations in the phantom. Fission track detectors have been found to be a reliable tool for neutron dosimetry for geometries in which one wishes to know neutron dose values which may vary considerably over distances of 1 cm or less

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

International Nuclear Information System (INIS)

Jensen, P.K.; Kunzendorf, Helmar; Hansen, Kirsten

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 uranium content. The initial track length distribution is taken into account. A relation between the measured track length distribution and age is given which includes correction for partial annealing. The annealing model used is the fanning Arrhenius plot. It is shown that track length distributions measured in transmitted light are biased favouring short tracks compared with measurements in reflected light. Testing of the model is performed on apatites from a tuffaceous sandstone from Bornholm (Denmark) yielding an estimate of the thermal history for the period of about 280 Ma back in time. (author)

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.

Thorium determination in water and biological materials by fission track

International Nuclear Information System (INIS)

Melo Ferreira, A.C. de.

1989-01-01

As a segment of a research programme on the study of bioaccumulation of radionuclides, in animals and vegetables from Morro do Ferro, Pocos de Caldas, MG, a fission track method for the determination of low levels of thorium in environmental samples was developed as an alternative for alpha spectroscopy. The study was carried out in early alpha spectroscopy samples, containing high levels of 228 Th activity, which makes difficult the 232 Th determination. A dry way method for thorium evaluation was developed. Pieces of membrane filters, containing La F 3 (Th), coupled to Makrofol detectors, were irradiated in the core of a research reactor, IEA-R1 (IPEN). (author)

Observations on the geometries of etched fission and alpha-recoil tracks with reference to models of track revelation in minerals

International Nuclear Information System (INIS)

Jonckheere, R.; Enkelmann, E.; Stuebner, K.

2005-01-01

The kinetic and atomistic theories of crystal growth and dissolution are used to interpret the shapes and orientations of fission-track, recoil-track and dislocation etch pits in tri-octahedral phlogopite and di-octahedral muscovite. An atomistic approach combined with symmetry considerations lead to the identification of the periodic bond chains that determine the etch pit morphologies and relative etch rates at a chemical level: O-Mg-O in phlogopite, O-Mg-O-Fe in biotite and O-Al-O in muscovite. Using first-order estimates of the bond strengths, it is possible to account for the relative track etch rates in these minerals. The reported, sometimes simultaneous, occurrence of triangular, polygonal and hexagonal etch pit contours in phlogopite, some of which violate the crystal symmetry, suggests that the cohesion of the phlogopite lattice is lost over a much larger radius than that of the track core around the trajectories of particles for which the energy loss exceeds a threshold value. This is interpreted as an indication of pronounced sublattice and anisotropic effects during track registration

Fission track ages and uranium concentration of apatites of different rocks of South India

International Nuclear Information System (INIS)

Nand Lal; Nagpaul, K.K.; Nagpal, M.K.

1975-01-01

The uranium concentration and ages of apatite grains of various rocks of South India have been measured by fission track technique. The ages range from 100 m.y. to 730 m.y. whereas uranium concentrations vary from 0.5 to 23.8 atom/million atoms of the apatite mineral. The ages agree well with the Deccan volcanic and Ocean Cycle activities. (author)

Timing of tertiary extension in the Southern Canadian Cordillera: constraints from fission-track analysis in the Shuswap metamorphic complex

International Nuclear Information System (INIS)

Lorencak, M.; Seward, D.; Burg, J.-P.

1999-01-01

Full text: Nine zircon and eighteen apatite fission-track analyses have been made in order to determine the low temperature cooling history of the Shuswap metamorphic core complex, western Canada. The zircons vary in apparent age from 53.9 ± 5.6 to 37.5 ± 5.0 Ma and the apatites from 48.5 ± 3.2 to 27.7 ± 3.4 Ma. In the footwall of the detachment faults defining the core complex, the cooling histories show a similarity until temperatures of ∼250 C were reached at about 45 Ma. From then on, activity on two normal faults, the Columbia River Fault and the Victor Creek Fault, controlled the regional cooling pattern. The ages and the combination of ages fall into four groups and on the basis of the fission-track data, we suggest that the region can now be divided into four thermotectonic units which are the result of differing tectonic controls during regional extension. Additionally, a complete cooling history of the Shuswap core complex can now be reconstructed, using constraints from U-Pb, Rb-Sr and K-Ar age data from several authors as well as the fission track results presented here. Copyright (1999) Geological Society of Australia

Determination of the effective range of fission fragments in UO2 and of the disintegration constant for the spontaneous fission of Uranium 238

International Nuclear Information System (INIS)

Spaggiari, E.R.V.

1980-01-01

Results are presented of measurements realized aiming to determine the disintegration constant of spontaneous fission of U-238, with a discussion of the method utilized in the detection of fission tracks in muscovite. Several blades of mica were placed between two cylinders of Uo 2 to be irradiated with the fragments of spontaneous fission of U-238, and the fission tracks duly enlarged after a convenient chemical action were observed with a projection optical microscope. The effective thickness of UO 2 contributing to the observed tracks was measured through the irradiation of mica samples juxtaposed to the UO 2 cylinder, with 14,0 MeV neutrons from the (d,t 2 ) reaction. The detection efficiency of fission tracks originated in that thickness is practically 100% [pt

Fission track analysis of Pu in small specimens of biological material: Technical progress report, August 1, 1987--July 31, 1988

International Nuclear Information System (INIS)

Wrenn, M.E.

1988-01-01

The objective of this research is to develop a highly specific and ultrasensitive method capable of detecting 100 aCi/liter of 239 Pu in human urine. The method using neutron induced fission track analysis is to be made free of interference from uranium, the only naturally occurring element with an isotope which fissions with thermal neutrons. A simplified flow diagram for the method is shown in Figure 1. Briefly 239 Pu is coprecipitated quantitatively from urine with rhodozonic acid. The precipitate containing the 239 Pu is dissolved in HCl and is sequentially passed through two ion exchange columns and reduced in volume. The element is then deposited in a circular area on a thick polycarbonate detector and a thinner detector is placed over the circular deposit. The plastic detectors are then irradiated to a high thermal neutron fluence in a research reactor. The detectors are etched in a caustic solution for controlled times and temperatures in order to develop the fission tracks. Images of tracks are formed both on the thin and thick plastic detectors. Total tracks in the thinner detector are measured with a locally developed spark counter and in the thick plastic are measured by counting with a microscope. The results will be made quantitative by constructing a calibration curve for 239 Pu. 3 refs., 9 figs., 3 tabs

Fission track dating of tuffaceous eocene formations of the North Bakony Mountains (Transdanubia, Hungary)

International Nuclear Information System (INIS)

Dunkl, I.

1990-01-01

Fission track dating was performed in accessory minerals of strongly altered, clay mineralized tuffite strata lying in the upper part of the Eocene sequence of the North Bakony Mountains. The homogeneity of the fission track (FT) ages measured on apatite and zircon refers only to insignificant redeposition, no remarkable mingling of the detrital matter vould be stated. The average of the FT-ages falls to the Bartonian, into the time interval determined by nannoplankton guide horizons for the volcanic activity (41.9 ± 4.1 Ma). As to their biostratigraphic age the Middle Eocene samples show an FT-average of 44.2 ± 3.4 Ma, the average of the Upper Eocene group is 39.9 ± 4.1 Ma. The difference between the two groups refers to the two phases of the volcanic activity. The first maximum of volcanism generated the Upper Lutetian to Bartonian glauconitic sequence while the second maximum at the Bartonian-Priabonian boundary produced the tuff strata. The strata in the neighbouring areas relate to continuous volcanism in the Upper Eocene, in the studied area, however, the upper part of the Priabonian was eroded. (author) 51 refs.; 4 figs.; 1 tab

Determination of the uranium concentration in water samples by the technique of fission track recording

International Nuclear Information System (INIS)

Geraldo, L.P.

1979-01-01

The technique of fission track register was developed for the determination of micrograms of uranium. The Makrofol KG, a synthetic plastic made by Bayer, was used as the detector and the wet method was utilized. The detector calibration curve allows the determination of the uranium concentration in a sample within an interval from 8.0 to 0.4μgU/L, the total error ranging from 3.3% to 29.0% respectively. The method was used in the determination of the uranium content in various water samples, obtained from various sources like rivers, sea etc. in the state of Sao Paulo, Brazil. Results were compared with those obtained by other authors using different methods. The average concentration found in sea waters (3.27 +- 9.12μgU/l) by this method is compatible with the international average accepted value of 3.3μgU/l, irrespective of site and depth. The determination of the uranium content by fission track counting has proved to be very convenient. (Author) [pt

Evidence of pair correlations in actinide neutron-induced fission cross sections

International Nuclear Information System (INIS)

Maslov, V.M.

2000-01-01

It is shown that irregularities in fission cross sections in MeV incident neutron energy region could be attributed to the interplay of few-quasiparticle excitations in the level density of the fissioning and residual nuclei. It is suggested the intrinsic quasiparticle state density modelling approach both at stable and saddle-point deformations. The experimental manifestation of few-quasiparticle irregularities in the level density depends on the fission barrier structure and internal excitation energy at the saddle point, corresponding to the higher barrier hump. The explicit evidence is observed in case of fissile and non-fissile target nuclides [ru

The etching property of the surface of CR-39 and the track core radius of fission fragment

CERN Document Server

Mineyama, D; Yamauchi, T; Oda, K; El-Rahman, A

2002-01-01

The etch pits of fission fragments in CR-39 detector have been observed carefully using an atomic force microscope (AFM) after extremely short chemical etching in stirred 6N KOH solution kept at 70degC. It was found that there existed a thin layer where the bulk etch rate is relativity from large the etch-pit growth curve for the etching duration between 10 and 1800 seconds. The track core radius of fission fragment was evaluated to be about 6 nm from the extrapolation of the growth curve in a thinner region. (author)

Fission track dating of authigenic quartz in red weathering crusts of carbonate rocks in Guizhou province

International Nuclear Information System (INIS)

Liu Xiuming; Wang Shijie; Zhang Feng

2004-01-01

The Cenozoic evolution history of Guizhou Province, which is located on the southeastern 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 Ma to 25 Ma in the four profiles, significantly younger than the ages of Triassic and Cambrian parent rocks. In combination with the regionally geological evolution history during the period from 25 Ma 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 weathering processes of carbonate rocks. The recorded ages of quartz from the four profiles are consistent with the episodes of planation surfaces on the Qinghai-Tibet Plateau, the 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. (authors)

Thermal history of the multi-well experiment (MWX) site, Piceance Creek Basin, Northwestern Colorado, derived from fission-track analysis

International Nuclear Information System (INIS)

Kelley, S.A.; Blackwell, D.D.

1990-01-01

Fission-track analysis of apatite and zircon from 19 depth intervals in two drill holes at the MWX site in the Piceance Creek Basin, Colorado, is used to determine the burial and subsequent cooling history of the Upper Cretaceous Mesaverde Group and the Paleocene Wasatch Formation. The fission-track data, as well as available temperature, vitrinite reflectance, and geological information, indicate that the sampled sediments attained maximum burial at approximately 10 Ma, with maximum temperatures in the 150-200 0 C range. After 10 Ma the sediments began to cool during erosion related to the downcutting of the Colorado River, which lies just to the north of the MWX site. The heat flow in this area has remained relatively constant for the past 10 Ma. (author)

Inverted Apatite (U-Th)/He and Fission-track Dates from the Rae craton, Baffin Island, Canada and Implications for Apatite Radiation Damage-He Diffusivity Models

Science.gov (United States)

Ault, A. K.; Reiners, P. W.; Thomson, S. N.; Miller, G. H.

2015-12-01

Coupled apatite (U-Th)/He and fission-track (AFT) thermochronology data from the same sample can be used to decipher complex low temperature thermal histories and evaluate compatibility between these two methods. Existing apatite He damage-diffusivity models parameterize radiation damage annealing as fission-track annealing and yield inverted apatite He and AFT dates for samples with prolonged residence in the He partial retention zone. Apatite chemistry also impacts radiation damage and fission-track annealing, temperature sensitivity, and dates in both systems. We present inverted apatite He and AFT dates from the Rae craton, Baffin Island, Canada, that cannot be explained by apatite chemistry or existing damage-diffusivity and fission track models. Apatite He dates from 34 individual analyses from 6 samples range from 237 ± 44 Ma to 511 ± 25 Ma and collectively define a positive date-eU relationship. AFT dates from these same samples are 238 ± 15 Ma to 350 ± 20 Ma. These dates and associated track length data are inversely correlated and define the left segment of a boomerang diagram. Three of the six samples with 20-90 ppm eU apatite grains yield apatite He and AFT dates inverted by 300 million years. These samples have average apatite Cl chemistry of ≤0.02 wt.%, with no correlation between Cl content and Dpar. Thermal history simulations using geologic constraints, an apatite He radiation damage accumulation and annealing model, apatite He dates with the range of eU values, and AFT date and track length data, do not yield any viable time-temperature paths. Apatite He and AFT data modeled separately predict thermal histories with Paleozoic-Mesozoic peaks reheating temperatures differing by ≥15 °C. By modifying the parameter controlling damage annealing (Rmr0) from the canonical 0.83 to 0.5-0.6, forward models reproduce the apatite He date-eU correlation and AFT dates with a common thermal history. Results imply apatite radiation damage anneals at

Experimental study of a methodology for Fission-track Dating without neutron irradiation

International Nuclear Information System (INIS)

Hadler, J.C.; Iunes, P.J.; Tello, C.A.; Chemale, F.; Kawashita, K.; Curvo, E.A.C.; Santos, F.G.S.; Gasparini, T.E.; Moreira, P.A.F.P.; Guedes, S.

2009-01-01

To carry out the dating by the Fission Track Method (FTM) the international community that works with this method employs methodologies in which the mineral to be dated must be irradiated with neutrons. Such irradiation, performed in a nuclear reactor, demand a relatively long waiting time so that the activity of the sample attain a proper level for handling. The present work aims to establish a methodology that makes possible the dating by FTM using a mass spectrometer instead of a nuclear reactor. This methodology was applied to apatite samples from Durango, Mexico.

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

The obsidian from Quiron (Salta Province, Argentina): a new reference glass for fission-track dating

Energy Technology Data Exchange (ETDEWEB)

Bigazzi, G. [Istituto di Geoscienze e Georisorse, C.N.R., Area della Ricerca di Pisa, V.G. Moruzzi, 1, 56124 Pisa (Italy)]. E-mail: g.bigazzi@igg.cnr.it; Laurenzi, M.A. [Istituto di Geoscienze e Georisorse, C.N.R., Area della Ricerca di Pisa, V.G. Moruzzi, 1, 56124 Pisa (Italy); Viramonte, J.G. [Instituto Geonorte, Universidad Nacional de Salta and Conicet, Buenos Aires 177, 4400 Salta (Argentina)

2005-12-01

In the course of a geochronological study of the volcanic activity in the Andean Cordillera in northern Argentina, we have found in the El Quevar volcanic complex (24 deg. 19{sup '}S/66 deg. 43{sup '}W,6180m) a phenocryst poor obsidian (Quiron obsidian) showing an unusually high spontaneous track density. Defects which might produce 'spurious' tracks are virtually absent. Application of fission-track dating using an absolute approach, based on the IRMM-540 standard glass for neutron fluence measurements, yielded an apparent age of 7.27+/-0.29Ma(1{sigma}) and a plateau age of 8.99+/-0.31Ma(1{sigma}). A {sup 40}Ar-{sup 39}Ar isochron age on biotite of 8.61+/-0.04Ma(1{sigma}) was already available for the Quiron rhyolite. We determined further {sup 40}Ar-{sup 39}Ar ages on several chips of the glass itself using two analytical approaches: total fusion with a focussed laser beam (LTFA) and a step-heating approach using a de-focussed laser beam (LSHA). We have obtained a weighted average of 8.77+/-0.09Ma, an isochron age of 8.71+/-0.12Ma and an integrated age of 8.77+/-0.09Ma for LTF analyses, and a w.a. of 8.75+/-0.09Ma, an iso.a. of 8.77+/-0.09Ma and an int.a. of 8.77+/-0.09Ma for LSH analyses (all age errors are 2{sigma}). The Quiron obsidian is very easy to analyse for its high spontaneous track density and because microlites which might produce spurious tracks are very rare. Independent reference {sup 40}Ar-{sup 39}Ar ages determined in different laboratories are available. For these reasons we believe that this glass may be very useful for testing fission-track system calibrations and apparent age correction procedures. Splits of obsidian Quiron will be distributed upon request to colleagues who intend to test it.

Cumulative fission yield of Ce-148 produced by thermal-neutron fission of U-235

International Nuclear Information System (INIS)

Hasan, A.A.

1984-12-01

Cumulative fission yield of 148 cesium isotopes and some other fission products produced by thermal-neutron fission of 235 uranium is determined by Germanium/Lithium spectroscopic methods. The measuremets were done at Tsing-Hua open pool reactor using 3 to 4 mg of 93.15% enriched 235 uranium samples. Gamma rays are assigned to the responsible fission products by matching gamma rays energies and half lives. Fission rate is calculated by fission track method. Cumulative fission yields of 148 cesium, 90 krypton, 130 iodine, 144 lanthanum, 89 krypton, 136 xenon, 137 xenon and 140 cesium are calculated. This values are compared with previously predicted values and showed good agreement. 21 Ref

Response study of fission track detectors using two different moderator designs in a high-energy radiation field

Energy Technology Data Exchange (ETDEWEB)

Mayer, S. [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)], E-mail: Sabine.Mayer@psi.ch; Boschung, M.; Fiechtner, A. [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Fuerstner, M. [CERN, CH-1211 Geneva 23 (Switzerland); Wernli, C. [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

2008-02-15

Fission track detectors in the center of moderating spheres are routinely used to measure the ambient dose equivalent due to neutrons in the environmental dosimetry at Paul Scherrer Institut (PSI). Originally, the system was designed to cope with neutrons from skyshine effects. Later, the system was also adapted behind the shielding of PSI's accelerators. Nowadays, as a consequence of continuously upgrading accelerator energies and intensities, the neutron energy behind thick shielding can range from fractions of eV to about 1 GeV (e.g. at CERN). For this reason a measurement campaign in a high-energy stray radiation field at CERN's High-Energy Reference Field Facility (CERF) was initiated to study and compare the response of the already existing detector-moderator configuration and a new design, the 'GSI ball'. Employing an additional lead layer in a moderator sphere of 32.5 cm diameter, the GSI ball was primarily designed for the use with thermoluminescent based dosimeters in its center in order to optimize the response for the measurement of H*(10) to higher neutron energies. In this work, the measurement results for fission track detectors using two different radiator materials in the PSI and the GSI moderator are presented. Based on these studies, on the one hand, field calibration factors for the use in presumably similar high-energy fields around accelerators could be deduced. On the other hand, it could be shown that there is no need to replace the established PSI moderator by the GSI moderator since the combination of fission track detector and GSI moderator does not result in a significant sensitivity improvement.

Response study of fission track detectors using two different moderator designs in a high-energy radiation field

International Nuclear Information System (INIS)

Mayer, S.; Boschung, M.; Fiechtner, A.; Fuerstner, M.; Wernli, C.

2008-01-01

Fission track detectors in the center of moderating spheres are routinely used to measure the ambient dose equivalent due to neutrons in the environmental dosimetry at Paul Scherrer Institut (PSI). Originally, the system was designed to cope with neutrons from skyshine effects. Later, the system was also adapted behind the shielding of PSI's accelerators. Nowadays, as a consequence of continuously upgrading accelerator energies and intensities, the neutron energy behind thick shielding can range from fractions of eV to about 1 GeV (e.g. at CERN). For this reason a measurement campaign in a high-energy stray radiation field at CERN's High-Energy Reference Field Facility (CERF) was initiated to study and compare the response of the already existing detector-moderator configuration and a new design, the 'GSI ball'. Employing an additional lead layer in a moderator sphere of 32.5 cm diameter, the GSI ball was primarily designed for the use with thermoluminescent based dosimeters in its center in order to optimize the response for the measurement of H*(10) to higher neutron energies. In this work, the measurement results for fission track detectors using two different radiator materials in the PSI and the GSI moderator are presented. Based on these studies, on the one hand, field calibration factors for the use in presumably similar high-energy fields around accelerators could be deduced. On the other hand, it could be shown that there is no need to replace the established PSI moderator by the GSI moderator since the combination of fission track detector and GSI moderator does not result in a significant sensitivity improvement

A study of the effect of natural radiation damage in a zircon crystal using thermoluminescence, fission track etching and X-ray diffraction

International Nuclear Information System (INIS)

Amin, Y.M.

1989-01-01

The natural radiation damage in zircon caused by the decay of uranium and thorium, present as impurities, is studied. The radiation damage is first gauged by etching the fission tracks. It is found that thermoluminescence (TL) sensitivity (defined as light output per unit test-dose) decreases as the radiation damage increases, suggesting a destruction of TL centers. The spacing d of the (112)-plane is also measured. It is also found that the d-value increases with radiation damage, suggesting the displacement of atoms from their normal lattice sites. However, as the track density increases beyond ≅ 3x10 6 tracks/cm 2 , the d-value remains at ≅ 2.52 A. By annealing the crystal, the displaced atoms are found to return to the original lattice sites, and this is followed by a reduction in d-value as well as the recovery of TL sensitivity. The fission track density also decreases and all the tracks disappear at the annealing temperature of ≅ 800 0 C. (orig.)

Relationship between thermotectonic evolution of Serra do Mar mountain range and Santos Basin, SP, Brazil, accessed through fission track analysis in apatite

International Nuclear Information System (INIS)

Hadler, J.C; Tello, S.C.A; Iunes, P.J.; Guedes, S; Hackspacher, P; Paulo, S.R; Ribeiro, L.F.B

2001-01-01

Thermal evolution of tectonic units and its reflection on neighbouring basins adds importance to the study of some geological regions because this kind of process can be related to the origin of petroleum fields. During the last decade, thermochronology using the fission track method (FTM) in apatite was set up as an useful tool to obtain information from thermal histories (for instance, Rhorman et al., 1996; Amaral et al., 1997; Guedes et al., 2000). Thermal instability of fission tracks in some minerals is the basis of thermochronology by the FTM. In the case of apatite, there is a concordance in the temperature-time interval (∼70-110 o C for several tens of Ma) in which prehistoric forests were transformed in underground petroleum and a measurable shortening of fossil tracks. When spontaneous fission of a 238 U nucleus take place inside a mineral, a disarranged zone is created in the neighboring crystalline lattice (the latent track). This phenomenon is reversible since the atoms that were dislocated due to fission can come back to their original positions as consequence of thermal episodes of geological origin. This process can lead to partial or total reconstruction of the crystalline lattice around a latent track; it is named annealing in the literature. Fission tracks are continuously produced in apatite. Then, those prior to a thermal episode should present shorter lengths than those produced after it. In this way, by measuring the track length distribution at the optical microscope, after a suitable etching, one can obtain information about the thermal history of the region where an apatite sample was collected (Amaral et al., 1997). In spite of the effort carried out to understand track annealing kinetics (for instance, Carlson, 1990; Hadler et al., 2001), this phenomenon is not well known yet. To avoid this difficulty, annealing has been described using empirical models based on the best fitting of experimental data obtained in times compatible with

Enlarging the fission fragment tracks in glass detectors by etching in weak solutions of HF - a safe etchant

International Nuclear Information System (INIS)

Singh, V.P.; Sharma, A.P.

1982-01-01

The effect of etchant concentration and temperature on track revelation properties of soda glass detectors has been studied. Etch rate ratio, maximum observable diameter and the energy resolution of the fission fragment tracks of 252 Cf in glasses are increased when the samples are etched in 1.25 vol% HF as compared to higher concentrations of HF and other etching solutions. The critical angle of etching is found to decrease with decrease in etchant concentration. The activation energies for bulk etching and track etching have also been estimated. Better results were obtained by using lower etching temperatures. (author)

Nuclear tracks in the Angra dos Reis and Moore County meteorites

International Nuclear Information System (INIS)

Carver, E.A.; Anders, E.

1976-01-01

Charged particle tracks were studied in the Angra dos Reis and Moore County meteorites, both of which contain an unexplained excess of He 4 . A selective annealing method was used to resolve cosmic-ray tracks from fission tracks. It gave the following cosmic-ray and fission-track densities, in units of 10 6 cm -2 : Angra dos Reis 1.3 to 4.4 and 7.8; Moore Co. feldspar 1.9 to 3.0 and 0.51; Moore Co. pigeonite 2.0 to 2.9 and 0.078 to 0.35. The fission-track densities are 10 to 100 times higher than expected from U 238 ; the excess is probably due to extinct Pu 244 . The Pu 244 /U 238 ratios at the start of track retention were 0.003 for Angra dos Reis and 0.002 to 0.03 got Moore Co. No evidence was found for fission tracks attributable to the unknown progenitor of excess He 4 in these meteorites; the fission branch of this progenitor comprises less than 10 -5 the α-branch. A search for pleochroic halos also gave negative results. The preatmospheric radii of the two meteorites are >= 13 and >= 7 cm. According to meteor theory, this implies geocentric velocities of >19 and >= 6 km/sec. The etching behaviour of Angra dos Reis augite is highly anomalous, giving rise to spurious angular anisotropies and skewed length distributions. This confirms similar observation by Fleischer et al (Proc. Apollo II Lunar Sci. Conf. Geochem. Cosmochim. Acta Suppl.; 1:2103 (1970)) on lunar augite. (author)

Thermo chronology by the fission track method of a passive marge (Ponta Grossa dome in south-eastern Brazil) and within a collision chain (external zone of the alpine arch in France)

International Nuclear Information System (INIS)

Medeiros Vignol Lelarge, M.L.

1993-01-01

The dating method by counting fission tracks on apatite (this rock is a geo-thermometer sensitive to weak temperature changes below 150 Celsius degrees) is an efficient tool for the thermal history of rocks. We have used this method in 2 different geological contexts: the Ponta Grossa dome in south-eastern Brazil and the alpine mountain in France. This dating method is based on the fact that some rocks like mica keep fossil remains of the passage of the fission products emitted during the simultaneous fission of uranium 238 present in the rock. This method requires the irradiation in a slow neutron flux of the sample because the initial quantity of uranium is unknown. The age t of the sample is given by the formula: t=(1/l 1 )*ln[1+(r s /r i )*(l 2 /l 1 )*F*σ*I] where: l 1 is the alpha decay constant of U 238 ; l 2 is the simultaneous fission decay constant of U 238 , r s is the number of fission tracks in the sample before the irradiation; r i is the number of fission tracks induced by the irradiation; F is the thermal neutron flux; σ is the thermal fission cross-section of U 235 ; and I is the isotopic rate U 235 /U 238 . This document is divided into 4 chapters. The first chapter presents the general principle of the method, the mechanisms capable of producing fission tracks and the techniques used to make these tracks visible with an optical microscope. The second chapter deals with the conditions of the irradiation and the calibration of the method. The 2 last chapters are dedicated to the applications to the 2 geological contexts. (A.C.)

Apatite fission track dating of the Northern Western Shield, Western Australia

International Nuclear Information System (INIS)

Weber, U.D.; Kohn, B.P.; Gleadow, A.J.W.

1999-01-01

Full text:The investigation of the thermotectonic evolution of the northern part of the Precambrian Western Shield of Western Australia using apatite fission track (AFT) thermochronology is the main focus of this study. The study area encompasses Precambrian rocks of the Pilbara Craton and the northern part of the Yilgarn Craton including the Narryer Gneiss Complex. AFT data, mostly from the Archaean cratons reveal cooling ages ranging between 260±8 Ma and 400±20 Ma. Mean confined horizontal track lengths fall between ∼12 and 13 μm with standard deviations ranging from 1.1-2.2 μm. Forward modelling of time-temperature history paths for representative samples reveals a period of regional cooling of at least ∼50 deg C in the late Palaeozoic. Most paths also show a second period of cooling of 25 deg C from temperatures of ∼80-85 deg C. This later cooling episode occurred in the Mesozoic but its timing is less well constrained. Assuming that the average present day geothermal gradient of ∼18±2 deg C per km - 1 was prevalent since the late Palaeozoic, then the minimum of ∼75 deg C of cooling predicted by the fission track modelling suggests overall denudation of at least ∼ 3.7-4.6 km of section since that time. Phanerozoic basins (Perth, Carnarvon and Canning) adjacent to the north and west of the northern Western Shield mostly continue offshore and form complex structures containing up to ∼ 15 km of predominantly clastic sediments of early Ordovician to late Cretaceous age. The basins are likely to have been depocentres for much of the detritus derived from the denudation inferred from the cooling recorded by the AFT. Possible causative events which could be linked to the observed late Palaeozoic cooling are tectonism related to the collision of Gondwanaland with Laurussia in Carboniferous time forming the supercontinent Pangea or a possible far-field effect related to the Alice Springs Orogeny. Further low temperature thermochronological studies

Apatite fission-track evidence of widespread Eocene heating and exhumation in the Yukon-Tanana Upland, interior Alaska

Science.gov (United States)

Dusel-Bacon, C.; Murphy, J.M.

2001-01-01

We present an apatite fission-track (AFT) study of five plutonic rocks and seven metamorphic rocks across 310 km of the Yukon-Tanana Upland in east-central Alaska. Samples yielding ???40 Ma AFT ages and mean confined track lengths > 14 ??m with low standard deviations cooled rapidly from >120??C to 40 Ma suggest partial annealing and, therefore, lower maximum temperatures (???90-105??C). A few samples with single-grain ages of ???20 Ma apparently remained above ???50??C after initial cooling. Although the present geothermal gradient in the western Yukon-Tanana Upland is ???32??C/km, it could have been as high as 45??C/km during a widespread Eocene intraplate magmatic episode. Prior to rapid exhumation, samples with ???40 Ma AFT ages were >3.8-2.7 km deep and samples with >50 Ma AFT ages were >3.3-2.0 km deep. We calculate a 440-320 m/Ma minimum rate for exhumation of all samples during rapid cooling. Our AFT data, and data from rocks north of Fairbanks and from the Eielson deep test hole, indicate up to 3 km of post-40 Ma vertical displacement along known and inferred northeast-trending high-angle faults. The predominance of 40-50 Ma AFT ages throughout the Yukon-Tanana Upland indicates that, prior to the post-40 Ma relative uplift along some northeast-trending faults, rapid regional cooling and exhumation closely followed the Eocene extensional magmatism. We propose that Eocene magmatism and exhumation were somehow related to plate movements that produced regional-scale oroclinal rotation, northward translation of outboard terranes, major dextral strike-slip faulting, and subduction of an oceanic spreading ridge along the southern margin of Alaska.

Measurements of the effective range of fission fragments in UO2 and the disintegration constant for spontaneous fission of 238U

International Nuclear Information System (INIS)

Spaggiari, E.R.V.

1978-01-01

The results of measuments of the disintegration constant for spontaneous fission in 238 U are presented, with a discussion on the method used for the detection of fission tracks in muscovite mica. Samples of muscovite mica sandwiched between two natural uranium dioxide cylinders were irradiated with fragments of spontaneous fission and the etched tracks counted with projetion optical microscope. The effective thickness of the UO 2 layer which contributed to the observed tracks was measured through irradiation of mica samples, in contact with the UO 2 cylinder with 14,0 MeV neutrons from a (d,t) reaction. (Author) [pt

Detection alpha particles and Cf-252 fission fragments with track solid detectors and with surface barrier detectors: efficiency determination

International Nuclear Information System (INIS)

Khouri, M.T.F.C.; Koskinas, M.F.; Andrade, C. de; Vilela, E.C.; Hinostroza, H.; Kaschiny, J.R.A.; Costa, M.S. da; Rizzo, P.; Santos, W.M.S.

1990-01-01

The technique of particle detection by solid track detectors, types of developing and analysis of results are presented. Efficiency measurements of alpha particle detection with Makrofol e and surface barrier detector are made. Detection of Cf-252 fission fragments is shown. (L.C.)

Trace uranium determination in beverages and mineral water using fission track techniques

International Nuclear Information System (INIS)

Cheng, Y.L.; Lin, J.Y.; Hao, X.H.

1993-01-01

The uranium contents of beverages and mineral water have been estimated using the technique of fission track analysis with polycarbonate detector. The U contents in beverages have been found to vary from 0.26 ± 0.03 to 1.65 ± 0.07 ppb, the average value is 0.93 ± 0.05 ppb. The mean U content in mineral water is 9.20 ± 0.16 ppb, which is ∼ 10 times higher than the mean U content of beverages. The present study shows the high U content in mineral water, indicating need for further investigation of U content in mineral water for the studies of radiation health hazards. (Author)

Fission studies of gold induced by (1665 MeV) π- using a CR-39 detector

International Nuclear Information System (INIS)

Muhammad Ikram Shahzad; Yasin, Zafar; Sher, Gul

2012-01-01

The fission cross section and fission probability of 197 Au, induced by (1665 MeV) π'-, have been studied using CR-39 track detectors. A 4π-geometry was used to count track statistics. A beam of negative pions of 1665 MeV was produced at AGS of Brookhaven National Laboratory, USA, and allowed to fall normally on the stack. Two detectors from the stack were scanned for fission fragment tracks after etching in 6N NaOH at 70 ℃. The statistics of fission fragment tracks in both detectors were obtained. It was found that there was a marked asymmetry of registered tracks with respect to the forward and backward hemispheres. This asymmetry could be partly accounted for on the basis of momentum transfer to the struck nucleus. On the basis of counting statistics fission cross section was measured, and fission probability was determined by dividing the fission cross section with the reaction cross section. The fission cross-section and fission probability were compared with the computed values using the cascade-exciton model code CEM95. (authors)

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.

Detection of alpha particles and Cf-252 fission fragments with solid track detectors and surface barrier detector. Efficiency calculation

International Nuclear Information System (INIS)

Khouri, M.T.F.C.; Koskinas, M.F.; Andrade, C. de; Vilela, E.C.; Hinostroza, H.; Kaschiny, J.E.A.; Costa, M.S. da; Rizzo, P.; Santos, W.M.S.

1990-01-01

A technique for particle detection by using track solid detector and also types of revealing and result analysis are presented concerned to Cf-252 fission fragments detection. Measurements of alpha particles detection efficiency using Makrofol E and surface barrier detector are performed. (L.C.J.A.)

On the use of thin natural uranium film dosimetry in mineral dating by the fission track method

International Nuclear Information System (INIS)

Hadler Neto, J.C.; Iunes, P.J.; Khouri, M.C.

1993-01-01

Three obsidian samples were irradiated in a neutron facility and their age was measured by the fission track method; using a thin uranium film dosemeter. The results were compared to others made previously on the same type of rock using conventional neutron dosimetry. The use of thin uranium film for age determination is discussed. (F.E.). 20 refs, 4 tabs

Reconstructing Post-Carboniferous History of the Krkonoše Piedmont Basin Using Detrital Apatite Fission-Track Data

Czech Academy of Sciences Publication Activity Database

Martínek, K.; Svojtka, Martin; Filip, Jiří

2006-01-01

Roč. 20, - (2006), s. 91-92 ISSN 1210-9606. [Meeting of the Central European Tectonic Studies Group /4./. Zakopane, 19.04.2006-22.04.2006] Institutional research plan: CEZ:AV0Z30130516 Keywords : fission-track * Krkonoše * apatite Subject RIV: DB - Geology ; Mineralogy http://geolines.gli.cas.cz/fileadmin/volumes/volume20/G20-091b.pdf

Femtosecond stimulated Raman evidence for charge-transfer character in pentacene singlet fission.

Science.gov (United States)

Hart, Stephanie M; Silva, W Ruchira; Frontiera, Renee R

2018-02-07

Singlet fission is a spin-allowed process in which an excited singlet state evolves into two triplet states. We use femtosecond stimulated Raman spectroscopy, an ultrafast vibrational technique, to follow the molecular structural evolution during singlet fission in order to determine the mechanism of this process. In crystalline pentacene, we observe the formation of an intermediate characterized by pairs of excited state peaks that are red- and blue-shifted relative to the ground state features. We hypothesize that these features arise from the formation of cationic and anionic species due to partial transfer of electron density from one pentacene molecule to a neighboring molecule. These observations provide experimental evidence for the role of states with significant charge-transfer character which facilitate the singlet fission process in pentacene. Our work both provides new insight into the singlet fission mechanism in pentacene and demonstrates the utility of structurally-sensitive time-resolved spectroscopic techniques in monitoring ultrafast processes.

Determination of the uranium concentration in samples of raw, retorted and spent shale from Irati, Parana-Brazil, by the fission track registration technique

International Nuclear Information System (INIS)

Cabral, R.G.

1981-02-01

The feasibility of the determination of uranium in oil shale, by the fission track registration technique is studied. The wet and dry methods were employed, using a Bayer policarbonate, Makrofol KG, as detector. It was created a new variant of the dry method. The fission track registration technique was used in samples of raw, retorted and spent shale from Irati, Parana in Brazil, 16 μg U/g, 20 μg U/g and 20μg U/g were found, respectively, with a total error ranging from 19% to 20%. Some experimental results were included for illustration and comparison. The feasibility of the determination of uranium in oil shale from Irati was verified. (Author) [pt

Trace uranium analysis in Indian coal samples using the fission track technique

International Nuclear Information System (INIS)

Jojo, P.J.; Rawat, A.; Kumar, Ashavani; Prasad, Rajendra

1993-01-01

The ever-growing demand for energy has resulted in the extensive use of fossil fuels, especially coal, for power generation. Coal and its by-products often contain significant amounts of radionuclides, including uranium, which is the ultimate source of the radioactive gas Radon-222. The present study gives the concentration of uranium in coal samples of different collieries in India, collected from various thermal power plants in the state of Uttar Pradesh. The estimates were made using the fission track technique. Latent damage tracks were not found to be uniformly distributed but showed sun bursts and clusters. Non-uniform distributions of trace elements are a very common phenomenon in rocks. The levels of uranium in the coal samples were found to vary from 2.0 to 4.9 ppm in uniform distributions and from 21.3 to 41.0 ppm in non-uniform distributions. Measurements were also made on fly ash samples where the average uranium concentration was found to be 8.4 and 49.3 ppm in uniform and non-uniform distributions, respectively. (author)

Fission-track dating of pumice from the KBS Tuff, East Rudolf, Kenya

Science.gov (United States)

Hurford, A.J.; Gleadow, A.J.W.; Naeser, C.W.

1976-01-01

Fission-track dating of zircon separated from two pumice samples from the KBS Tuff in the Koobi Fora Formation, in Area 131, East Rudolf, Kenya, gives an age of 2.44??0.08 Myr for the eruption of the pumice. This result is compatible with the previously published K-Ar and 40Ar/ 39Ar age spectrum estimate of 2.61??0.26 Myr for the KBS Tuff in Area 105, but differs from the more recently published K-Ar date of 1.82??0.04 Myr for the KBS Tuff in Area 131. This study does not support the suggestion that pumice cobbles of different ages occur in the KBS Tuff. ?? 1976 Nature Publishing Group.

Application of fission track method in the development study of coalbed methane

International Nuclear Information System (INIS)

Li Xiaoming; Peng Gelin

2002-01-01

In order to explore potential resource of coalbed methane in Xinji coal deposit of Huainan coalfield, its tectonic-thermal evolution history was studied by using fission track technique. The results showed that there had been 3 or more times of significant thermal events occurred in this area since the late Paleozoic Era. The paleo-geothermal gradient was higher than that of the present. It was estimated that the denudation thickness in this area should be over 2000 m. Mainly formed between 240-140 Ma, no abundant methane could be generated in such condition. Furthermore, the tectonic-thermal events would release the most of methane gases. So, the potential resource of the coalbed methane in this are might be limited

Rapid Late Miocene Exhumation in the Central Alps, Constrained by (U-Th)/He and Fission Track Thermochronology

Science.gov (United States)

Aramowicz, A.; Cosca, M.; Stockli, D.; Farley, K.; Seward, D.

2007-12-01

Zircon and apatite (U-Th)/He thermochronological data together with apatite fission track analyses are used to explore uplift and exhumation of the western part of the Aar massif in the central Swiss Alps. A total of 27 samples were collected from the surface and underground, from the world's deepest tunnel (Loetschberg NEAT), with an overall elevation difference of almost 2500 m. Zircon (U-Th)/He ages range from 5.5 to 7.6 Ma, apatite fission track ages range from 5.7 to 6.5 Ma and apatite (U-Th)/He ages range from 3 to 5.5 Ma. All zircon age-elevation profiles from three traverses, show distinct brakes in slope that mark a drastic, 10-fold acceleration of exhumation at 6 ± 0.5 Ma ago (from 0.3 km/Ma to 3 km/Ma). The trend of fast exhumation appears to be maintained in the apatite fission track data while apatite (U-Th)/He ages suggest a return to moderate, apparent exhumation rates of 0.5 km/Ma. We propose that the accelerated exhumation may be linked to the Messinian desiccation of the Mediterranean. During that event, Mediterranean sea level dropped locally by as much as 3 km which accelerated erosion in the Alps. Consequently, the erosion in the Alps must have increased. If wedge mechanics are considered, the increased erosional flux reduced the active width of the orogen and, during latest convergence, deformation focused in the internal parts of the Alps, i.e. Aar massif. This interpretation implies a strong and prompt feedback between external forcing and tectonic response of the orogen. The slower exhumation rate apparent from the apatite (U-Th)/He data may reflect a decline in deformation. Alternatively, due to its low closure temperature, this system is prone to resetting by heat advected through hydrothermal circulation. This scenario needs further investigation but abundant hot-water (ca. 50 °C) discharge in the sampled tunnel is not uncommon.

Apatite fission track analysis for revealing tectonic events of the Bayinguole area in the west section of Eastern Kunlun Mountains, northern Qinghai-Tibet Plateau

International Nuclear Information System (INIS)

Chen Xiaoning; Yuan Wanming; Hao Nana; Duan Hongwei; Feng Yunlei; Zhang Aikui

2014-01-01

Background: Qimantage is an important tectonic metallogenic belt in western part of East Kunlun Mountain. It has experienced complex geological evolution, and significant mineralization. However, because of the plateau climate and inaccessibility, fewer research works have been done on this area, especially after Indo-sinian epoch. Purpose: Our work is to research tectonic activity, thermal history and uplifting around Bayinguole river in Qimantage belt. Methods: The apatite fission-track method was applied to research the tectonic setting, simulate the thermal history and calculate the uplift size and uplift speed. Results: A series of apatite fission track ages from granitoid samples in Bayinguole area of Eastern Kunlun Mountain were obtained, ranging from 120 Ma to 47 Ma that might be divided into three groups': 120-100 Ma, 67 Ma and 54-47 Ma. These ages reflected tectonic events in this area very well. Conclusions: The 120-100 Ma and 67 Ma ages present collision-convergences of Gangdese terrane and Himalayan terrane with their north-side terranes in Early Cretaceous and Late Cretaceous respectively. The ages of 54-47 Ma reflect post-orogenic stretching events in Eocene. Three stages of thermal evolution history are revealed by apatite fission track modeling in this area. Stage one 180-140 Ma is in the bottom temperature of apatite fission track anneal zone. Stage two 140-13 Ma records slow cooling. The last stage after 13 Ma records rapid cooling with temperature dropped 50℃. The uplifting ranges for these three stages are 1.0 km, 0.6 km and 1.4 km, respectively. The cumulative amount of uplift is about 3.0 km. The formula calculations for the 3 samples have their rock uplifts of 3623 m, 3317 m and 3769 m, respectively, averaging 3570 m, in accordance with the results based on the 3 stage thermal history. (authors)

Measurement of the 235U/238U fission cross section ratio in the 235U fission neutron spectrum

International Nuclear Information System (INIS)

Azimi-Garakani, D.; Bagheri-Darbandi, M.

1983-06-01

Fission cross section ratio of 235 U to 238 U has been measured in the fast neutron field generated by the 235 U fission plate installed on the thermal column of the Tehran Research Reactor (TRR) with a Makrofol solid state nuclear track detector. The experiments were carried out with a set of total six enriched 235 U and depleted 238 U deposits with different masses and Makrofol films of 0.025mm and 0.060mm thicknesses. The chemically etched tracks were counted by an optical microscope. No significant differences were observed with the thin and the thick films. The results showed that the average fission cross section ratio is 3.83+-0.25. (author)

Determination of the uranium content in phosphate fertilizers by the fission track registration technique

International Nuclear Information System (INIS)

Rocha, A.C.S. da.

1983-01-01

The application of fission track registration technique (SSNTD) to determine the uranium contents in phosphate fertilizers is dealt with. Samples were prepared by the wet method and the detector used was Makrofol Kg 10μm thick. The determination of uranium in phosphate fertilizer industry is of considerable interest in environmental control. The roots of vegetables tend to absorb and accumulate uranium form soil and so the human body could be contaminated. The phosphate fertilizers were originated from the phosphate-rich apatite deposits located in the high naturally radioactive areas of Araxa and Tapira in the state of Minas Gerais, Brazil. The results obtained ranged from 11.1 to 100ppm of uranium with a total error from 8.2 to 15.7%. The thorium contributions to the total track counting were discounted, though the actual concentrations of thorium in the samples were not determined. (Author) [pt

Why tracks

International Nuclear Information System (INIS)

Burchart, J.; Kral, J.

1979-01-01

A comparison is made of two methods of determining the age of rocks, ie., the krypton-argon method and the fission tracks method. The former method is more accurate but is dependent on the temperature and on the grain size of the investigated rocks (apatites, biotites, muscovites). As for the method of fission tracks, the determination is not dependent on grain size. This method allows dating and the determination of uranium concentration and distribution in rocks. (H.S.)

Mass dependence of positive pion-induced fission

International Nuclear Information System (INIS)

Khan, H.A.; Khan, N.A.; Peterson, R.J.

1991-01-01

Fission cross sections for a range of targets have been measured by solid-state track detectors following 80 and 100 MeV π + bombardment. Fission probabilities have been inferred by comparison to computed reaction cross sections. Fission probabilities for heavy targets agree with those for other probes of comparable energy and with statistical calculations. Probabilities for lighter targets are much above those previously observed or computed. Ternary fission cross sections and multiplicities of light fragments have also been determined

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.

New fission-track ages of mio-pliocene tuffs in the Sierras Pampeanas and Precordillera of Argentina

International Nuclear Information System (INIS)

Tabbutt, K.; Naeser, C.W.; Jordan, T.E.; Cerveny, P.F.

1989-01-01

Fission-track dates were determined for 18 volcanic tuff horizons located in nine Neogene foreland basin sequences distributed throughout the Precordillera and Sierras Pampeanas of Northwestern Argentina, an area of nearly horizontal subduction. These and other data indicate that a lower age limit for the sedimentary sequences studied is approximately 17 Ma. Therefore these fission-track dates constrain both the history of volcanic activity and the time of deposition in several foreland basins from the middle Miocene to Recent. Although the dates range from 3.6±0.8 Ma to 17.0±1.9 Ma, there is a marked increase in the number of ashes younger than 9 Ma. This implies that two distinct episodes of volcanic activity affected the region. The source of some of these tuffs is unknown but they are probably limited to the 'flat-slab' region between 27 deg and 32 deg S. Tuffs at Rio Blanco and Santa Florentina that are spatially associated with the Mogotes dacite domes of the Famatina Range represented magmatism bracketed from about 7 to 4 Ma in the region underlain by the flat-subducted plate. The stratigraphic relations in the basins show that the faulting that uplifted Sierra de Famatina was contemporaneous with the volcanism which reached the surface along the bounding faults. (Author) [es

Application of fission track technique for estimation of uranium concentration in drinking waters of Punjab

International Nuclear Information System (INIS)

Prabhu, S.P.; Sawant, P.D.; Raj, S.S.; Kumar, A.; Sarkar, P.K.; Tripathi, R.M.

2012-01-01

Drinking water samples were collected from four different districts, namely Bhatinda, Mansa, Faridkot and Firozpur, of Punjab for ascertaining the U(nat.) concentrations. All samples were preserved, processed and analyzed by laser fluorimetry (LF). To ensure accuracy of the data obtained by LF, few samples (10 nos) from each district were analyzed by alpha spectrometry as well as by fission track analysis (FTA) technique. For FTA technique few μl of water sample was transferred to polythene tube, lexan detector was immersed in it and the other end of the tube was also heat-sealed. Two samples and one uranium standard were irradiated in DHRUVA reactor. Irradiated detectors were chemically etched and tracks counted using an optical microscope. Uranium concentrations in samples ranged from 3.2 to 60.5 ppb and were comparable with those observed by LF. (author)

Emplacement time of Salai Patai carbonatite, Malakand, Pakistan, from fission track dating of zircon and apatite

International Nuclear Information System (INIS)

Qureshi, A.A.; Khan, H.A.

1991-01-01

Based on fission track dating of zircon and apatite, the emplacement history of Salai Patai carbonatite has been traced. It has been estimated that the carbonatite was emplaced along the thrust plane associated with the Indian-Eurasian plate collision during the Oligocene period followed by some thermal/tectonic episode during Early Miocene. This negates the previous proposal that all carbonatites found in Pakistan are a part of a 200 km long alkaline province associated with the rifting of Peshawar Valley during Late Cretaceous or early tertiary. (author)

Concentration of uranium in human cancerous tissues of Southern Iraqi patients using fission track analysis

International Nuclear Information System (INIS)

Al-Hamzawi, A.A.; Al-Qadisiyah University, Qadisiyah; Jaafar, M.S.; Tawfiq, N.F.

2015-01-01

The technique of nuclear fission track analysis with solid state nuclear track detectors CR-39 has been applied to determine concentrations of uranium in cancerous samples of human tissues that excised from patients in the three key southern Iraqi governorates namely, Basrah, Dhi-Qar, and Muthanna. These provinces were the sites of intensive military events during the Gulf Wars in 1991 and 2003. The investigation was based on the study of 24 abnormal samples and 12 normal samples for comparing the results. These samples include four types of soft tissues (kidney, breast, stomach and uterus). The results show that uranium concentrations in the normal tissues ranged between (1.42-4.76 μg kg -1 ), whereas in the cancerous tissues ranged between (3.37-7.22 μg kg -1 ). The uranium concentrations in the normal tissues were significantly lower than in the abnormal tissues (P < 0.001). (author)

Coulomb fission and transfer fission at heavy ion collisions

International Nuclear Information System (INIS)

Himmele, G.

1981-01-01

In the present thesis the first direct evidence of nuclear fission after inelastic scattering of heavy ions (sup(183,184)W, 152 Sm → 238 U; 184 W → 232 Th; 184 W, 232 Th → 248 Cm) is reported. Experiments which were performed at the UNILAC of the Gesellschaft fuer Schwerionenforschung in Darmstadt show the observed heavy ion induced fission possesses significant properties of the Coulomb fission. The observed dependence of the fission probability for inelastic scattering on the projectile charge proves that the nuclear fission is mediated by the electromagnetic interaction between heavy ions. This result suggests moreover a multiple Coulomb-excitation preceding the fission. Model calculations give a first indication, that the Coulomb fission proceeds mainly from the higher β phonons. In the irradiation with 184 W the fission probability of 232 Th is for all incident energies about 40% smaller that at 238 U. The target dependence of the Coulomb fission however doesn't allow, to give quantitative statements about the position and B(E2)-values of higher lying β phonons. (orig./HSI) [de

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 (

Cooling and erosion history of the Krkonoše Piedmont Basin (Bohemian Massif, Czech Republic) interpreted from apatite fission-track analysis

Czech Academy of Sciences Publication Activity Database

Svojtka, Martin; Filip, Jiří; Martínek, K.

2005-01-01

Roč. 7, - (2005), s. 4925-4926 ISSN 1607-7962. [European Geosciences Union, General Assembly. 24.04.2005-29.04.2005, Wien] R&D Projects: GA AV ČR KJB3111305 Institutional research plan: CEZ:AV0Z30130516 Keywords : Krkonoše * apatite * fission-track Subject RIV: DB - Geology ; Mineralogy

The effects of radiation damage accumulation and annealing on fission-track dating of titanite

International Nuclear Information System (INIS)

Enkelmann, Eva; Jonckheere, Raymond; Ratschbacher, Lothar

2005-01-01

Fission-track dating of titanite is hindered by the fact that track etching is anisotropic in fresh titanites and becomes isotropic with increasing radiation damage. Independent age determinations with the population method are problematic due to different track counting efficiencies (Q) for ρ s in unannealed and ρ i in annealed titanite. Independent age determinations with the external detector method depend on correction factors for the track registration geometries (G = 0.5), counting efficiencies (Q) and range deficit (R = 1.38); however, Q is unaffected by annealing. It was attempted to determine GQR through calculation, direct experiment and on the basis of age standards. The direct experiment involves measurements of the ratio of the induced-track densities in titanite and a co-irradiated external detector. The track densities in the internal titanite surfaces could not be measured but the results for the external surfaces confirm that this approach leads to a significant overestimation of GQR, due to prior annealing. The GQR-values determined on the basis of age standards are consistent with that obtained by calculation assuming that Q ∼ 1, although there is no experimental confirmation for this fact apart from their isotropic etching characteristics. The fact that identical GQR-factors were obtained on standards of different age and uranium content suggests that a single GQR-value is appropriate for dating titanites within a broad range of radiation damage. In terms of the ζ-calibration this implies that a single ζ-factor is also suitable for dating different titanites. These findings suggest that other factors besides the accumulation of alpha-recoil damage, such as a phase transition, could be co-responsible for the different etching characteristics of annealed and unannealed titanites

Detrital zircon fission-track thermochronology and magnetic fabric of the Amaga Formation (Colombia): Intracontinental deformation and exhumation events in the northwestern Andes

Czech Academy of Sciences Publication Activity Database

Piedrahita, V. A.; Bernet, M.; Chadima, Martin; Sierra, G. M.; Marín-Cerón, M. I.; Toro, G. E.

2017-01-01

Roč. 356, JUL 1 2017 (2017), s. 26-42 ISSN 0037-0738 Institutional support: RVO:67985831 Keywords : Panama-Choco Block * Northern Andean Block * Amaga Formation * zircon fission track * anisotropy of magnetic susceptibility Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 2.373, year: 2016

Neogene tectonic evolution and exhumation of the southern Ecuadorian Andes: a combined stratigraphy and fission-track approach

Science.gov (United States)

Steinmann, Michael; Hungerbühler, Dominik; Seward, Diane; Winkler, Wilfried

1999-06-01

Coastal marine and continental sedimentary facies of Middle to Late Miocene age are exposed in the Andes of southern Ecuador (Cuenca, Girón-Santa Isabel, Loja, Malacatos-Vilcabamba and Catamayo-Gonzanamá Basins). The chronostratigraphy of the basin series was established by zircon fission-track dating on a total of 120 tephra layers. Subsequently, the timing of tectonic events was estimated through the well-dated stratigraphic sequences and intervening unconformities. Sedimentation from ≈15 to 9 Ma (termed Pacific Coastal Stage) was dominantly of coastal marine type, extending over an area far greater than the present basin perimeters. It ended when a period of east-west-oriented compression at ≈9.5-8 Ma exhumed the region, and sedimentation was then restricted to smaller basins (termed Intermontane Stage). These Late Miocene continental sediments were for the first time sourced from the west in the rising Western Cordillera. Apatite fission-track analysis was applied to some of the tephras in the Cuenca Basin and also to the older (Eocene, 42-35 Ma) Quingeo Basin series in order to quantify the basin histories with respect to timing and amount of burial and later exhumation. In the Quingeo Basin burial of the oldest sediments reached temperatures of ˜100°C at 18 Ma, when they started to cool down during a period of exhumation. This process preceded the Pacific Coastal Stage development of the other basins. In the Cuenca Basin, the oldest sediments were buried to temperatures of ca. 120°C by 9 Ma, when a period of inversion began and a phase of erosion was dominant. This timing correlates well with that estimated from structural evidence. At ca. 6 Ma the cooling rate slowed down and maybe even reverted to a small increase in temperature until 3 Ma, when the final stages of exhumation took place. Assuming a geothermal gradient of 35°C/km, total uplift for this part for Ecuador is about 6100 m over the last 9 million years. Assuming a steady state

Zircon fission-track technique: a laboratory procedure adopted at the Institute of Geology, Academy of Sciences of the Czech Republic, v.v.i

Czech Academy of Sciences Publication Activity Database

Murakami, M.; Svojtka, Martin

2007-01-01

Roč. 20, - (2007), s. 13-19 ISSN N R&D Projects: GA MŠk 1K05030 Institutional research plan: CEZ:AV0Z30130516 Keywords : fission-track * zircon * Institute of Geology AS CR, v. v. i. Subject RIV: DB - Geology ; Mineralogy

New approaches in fission track geochronology as a tectonic tool: examples from the Transantarctic Mountains

International Nuclear Information System (INIS)

Fitzgerald, P.G.

1990-01-01

Apatite fission track analysis has been applied to study the uplift history and tectonics of the Transantarctic Mountains. An uplifted fossil apatite annealing zone has been identified in the apatite age vs elevation profile and is confirmed by track length data. A ''break in slope'' in the apatite age profile marks the base of the uplifted partial annealing zone and approximates the time of initiation of uplift of the mountains. Samples below the ''break in slope'' give information on the rate(s) of uplift. Samples above the break have apatite ages that vary significantly with elevation, but the gradient is not equal to an apparent uplift rate. Rather, it is due to inherited characteristics from the pre-existing partial annealing zone. These samples above the ''break in slope'' can be used as indicators of paleo-depth in the pre-uplift crust to determine the structure of an area and the displacement across faults. (author)

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)

Provenance and post-depositional low-temperature evolution of the James Ross Basin sedimentary rocks (Antarctic Peninsula) based on fission track analysis

Czech Academy of Sciences Publication Activity Database

Svojtka, Martin; Nývlt, D.; Murakami, Masaki; Vávrová, J.; Filip, Jiří; Mixa, P.

2009-01-01

Roč. 21, č. 6 (2009), s. 593-607 ISSN 0954-1020 R&D Projects: GA MŠk 1K05030 Institutional research plan: CEZ:AV0Z30130516 Keywords : James Ross Island * Seymour Island * Cretaceous–Palaeogene succession * fission track dating * zircon * apatite Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.496, year: 2009

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...

Shaping the Australian crust over the last 300 million years: insights from fission track thermotectonic imaging and denudation studies of key terranes

International Nuclear Information System (INIS)

Kohn, B.P.; Gleadow, A.J.W.; Brown, R.W.; O'Sullivan, P.B.; Foster, D.A.; Gallagher, K.

2002-01-01

Apatite fission track thermochronology is a well-established tool for reconstructing the low-temperature thermal and tectonic evolution of continental crust. The variation of fission track ages and distribution of fission track lengths are primarily controlled by cooling, which may be initiated by earth movements and consequent denudation at the Earth's surface and/or by changes in the thermal regime. Using numerical forward-modelling procedures these parameters can be matched with time-temperature paths that enable thermal and tectonic processes to be mapped out in considerable detail. This study describes extensive Australian regional fission track datasets that have been modelled sequentially and inverted into time-temperature solutions for visualisation as a series of time-slice images depicting the cooling history of present-day surface rocks during their passage through the upper crust. The data have also been combined with other datasets, including digital elevation and heat flow, to image the denudation history and the evolution of palaeo-topography. These images provide an important new perspective on crustal processes and landscape evolution and show how important tectonic and denudation events over the last 300 million years can be visualised in time and space. The application of spatially integrated denudation-rate chronology is also demonstrated for some key Australian terranes including the Lachlan and southern New England Orogens of southeastern Australia, Tasmania, the Gawler Craton, the Mt lsa lnlier, southwestern Australian crystalline terranes (including the Yilgarn Craton) and the Kimberley Block. This approach provides a readily accessible framework for quantifying the otherwise undetectable, timing and magnitude of long-term crustal denudation in these terranes, for a part of the geological record previously largely unconstrained. Discrete episodes of enhanced denudation occurred principally in response to changes in drainage, base

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)

A note on frequency distributions of fission tracks in apatite

International Nuclear Information System (INIS)

He, Z.; Lerche, I.

1989-01-01

Two different formulae, both purportedly describing track length reduction in apatite, are converted to forms useful in prediction of track length distributions along sedimentary burial history paths. Using the formalism, track length distribution data from four NW Canning Basin wells are inverted to determine the physical (chemical) parameters associated with the models as well as the heat flux variation with time. For each formula the resulting physical parameters are consistent among the wells tested but differ from laboratory-derived parameter values, and the thermal histories are consistent with those inferred from geological data. Comparison of the two models shows no evidence that one model should be favored over the other based on the data available. It is also shown that the resolution of the parameters is dependent not only on the quantity of the data but also on the ''quality'' -explicitly upon the variation and distribution with depth. (author)

Uranium distribution and age pattern of some deep-sea basalts from the Entrecasteaux area, South-western Pacific: a fission-track analysis

International Nuclear Information System (INIS)

Selo, M.; Storzer, D.

1981-01-01

The eight glass samples analysed by means of the fission-track method were recovered from deep-sea dredge sites 314D, 316D, 323D and 325D in the SW Pacific. The bulk uranium contents of the fresh remnants of unweathered glasses range between 51 ppb and 108 ppb. One glass from site 316D with a U-content of 227 ppb might be part of a dike intrusion. The basalts from all four sites are altered to various extents. Ambient temperatures prevailing during these alteration processes are estimated to have been 1 to 5 0 C at sites 314D and 325D; about 10 0 C at site 323D; but 40 to 110 0 C at site 316D. The measured fission-track ages of sites 314D, 323D and 325D scatter between 34 Ma in the north and 20 Ma in the south. At site 316D, they are exceedingly low, being from 4.4 to =< 0.7 Ma. All these ages are thermally lowered and required correction. The ages corrected for thermally induced partial track-loss are given. From these ages and the site positions, a spreading rate is deduced for the northern part of the North Loyalty Plateau, which comes close to values estimated for slow-spreading ridges. (author)

Thermal and exhumation history of Sakhalin Island (Russia) constrained by apatite U-Pb and fission track thermochronology

Science.gov (United States)

Glorie, Stijn; Alexandrov, Igor; Nixon, Angus; Jepson, Gilby; Gillespie, Jack; Jahn, Bor-Ming

2017-08-01

Sakhalin Island represents a key locality to study the tectonic evolution of the western Pacific. The island is located at the Amur-Okhotsk plate margin and records a complex thermotectonic history. Apatite double dating (U-Pb and fission track) and thermal history modelling were applied to three late Eocene granitoid massifs within central and southern Sakhalin: the Aniva, Okhotsk and Langeri complexes. Apatite U-Pb results yield consistent late Eocene (∼40-37 Ma) ages, suggesting rapid post-magmatic cooling. Apatite fission track results reveal bimodal age distributions with late Eocene - early Oligocene (∼38-33 Ma) and early Miocene (∼20-17 Ma) age populations that can be correlated with variations in Uranium and Chlorine concentrations. Thermal history modelling translates the AFT age bimodality into two-phase cooling histories. The timing of the early cooling phase (∼38-33 Ma) corresponds with the apatite U-Pb ages, indicating rapid cooling to at least ∼100 °C during the late Oligocene. The second cooling phase at ∼20-17 Ma cooled the samples to near-surface temperatures. Both cooling phases correspond with regional unconformities and subsequent accelerations in sedimentation rate, suggesting that cooling was a response to rapid exhumation. In addition, our data suggests that the studied terranes record differential exhumation with respect to the structural architecture. The Miocene exhumation pulse is coeval with the timing of transpressional fault displacement and the subsequent opening of the Kuril Basin.

Determination of trace uranium in atmospheric precipitation of the Xiangjiang river valley by fission track method

International Nuclear Information System (INIS)

Zhai Pengji; Kang Tiesheng

1986-01-01

In this work the uranium contents in atmospheric precipitations in the region of the Xiangjiang River valley have been measured by fission track method, which range from 0.008 to 1.5 ppb. The majority of them are below 0.1 ppb. The uranium contents in the samples form different geographical positions are obviously different. Sometimes the differences in uranium contents of the samples from the same area collected at different times are also great. A preliminary discussion is given on the sources of uranium in atmospheric precipitation and on the reason of the difference in contents

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

Multiphase cooling and exhumation of the Krkonoše Piedmont Basin during Mesozoic - Cenozoic basin inversion based on apatite fission track analysis

Czech Academy of Sciences Publication Activity Database

Martínek, K.; Svojtka, Martin; Filip, Jiří

2008-01-01

Roč. 34, 4/6 (2008), s. 1353003-1353003 ISSN 0161-6951. [International Geological Congress /33./. 06.08.2008-14.08.2008, Oslo] R&D Projects: GA AV ČR KJB3111305 Institutional research plan: CEZ:AV0Z30130516 Keywords : fission track * apatite * Krkonoše Piedmont basin Subject RIV: DB - Geology ; Mineralogy

Tracking of fission products release during refueling operations

International Nuclear Information System (INIS)

Agarwal, Sharad; Prajapat, M.K.; Vyas, Shyam; Hussain, S.A.

2001-01-01

It has been always observed that the release of fission products increase during refueling operations. At RAPP-3 and 4 an attempt has been made to follow-up the change in fission products activity release at each stage of refueling operation and quantification of concentrations of various radionuclides. This exercise was also extended to refueling operation of the channels containing suspected failed fuel. A level of FPNG ( 133 Xe) was observed to increase by a factor of about 10-40 during refueling of failed channel as compared to healthy channel. It can be concluded that by monitoring FPNG levels in exhaust status of the healthiness of spent fuel can be found out. This report discusses in detail the experiment conducted for this purpose. (author)

Determination of the uranium concentration in apatite by the fission - track registration technique

International Nuclear Information System (INIS)

D'Oliveira Cardoso, D.

1983-01-01

The feasibility of using the fission-track registration technique to determine the uranium content in the phosphate rock beneficiation steps carried on by CompanhiA Arafertil, Araxa, Minas Gerais, Brazil is studied. This determination is of considerable interest to the environmental control of the Arafertil installations as well as of its surroundings or of the areas where these products will be used. The so called wet method was adopted and a 10 μm polycarbonate foil, fabricated by Bayer under the trade name Makrofol KG was used as detector. From the calibration curve obtained, it was possible to determine uranium contents in sample solutions ranging from 21 to 212 μg U/1 with an accuracy of 8 to 14.7%, respectively. The results obtained demonstrated that the technique used is appropriate to the purposes previously aimed at. (Author) [pt

An extensive apatite fission-track study throughout the Northern Apennines Nappe belt

International Nuclear Information System (INIS)

Abbate, E.; Balestrieri, M.L.; Bigazzi, G.; Ventura, B.; Zattin, M.; Zuffa, G.G.

1999-01-01

This paper takes into consideration more than 100 apatite fission-track analyses on samples coming from an approximately west-east cross-section throughout the Northern Apennines. This collisional chain is made of structural units and nappes (Ligurian and Tuscan Nappe) accreted to the Adriatic Foreland during the Neogene, which overthrust the Miocene turbiditic successions of the Cervarola and Marnoso-arenacea Formations. Different cooling ages and degrees of annealing delineate different evolution histories for these units. Exhumation of the western outcrops of the Ligurian Nappe can be placed at 8 Ma and follows a first denudation event occurred in Eocene times. Timing of exhumation decreases eastwards. A break in this general trend is shown by the Apuan Alps, that occupy an intermediate position and yielded the youngest cooling ages. In the external part of the Marnoso-arenacea foredeep deposits this tendency could not be tested because total annealing of the apatite system has not been reached. In this case, modeling of data allows evaluating maximum burial temperatures

Chemical Production using Fission Fragments

International Nuclear Information System (INIS)

Dawson, J. K.; Moseley, F.

1960-01-01

Some reactor design considerations of the use of fission recoil fragment energy for the production of chemicals of industrial importance have been discussed previously in a paper given at the Second United Nations International Conference on the Peaceful Uses of Atomic Energy [A/Conf. 15/P.76]. The present paper summarizes more recent progress made on this topic at AERE, Harwell. The range-energy relationship for fission fragments is discussed in the context of the choice of fuel system for a chemical production reactor, and the experimental observation of a variation of chemical effect along the length of a fission fragment track is described for the irradiation of nitrogen-oxygen mixtures. Recent results are given on the effect of fission fragments on carbon monoxide-hydrogen gas mixtures and on water vapour. No system investigated to date shows any outstanding promise for large-scale chemical production. (author) [fr

Improving process methodology for measuring plutonium burden in human urine using fission track analysis

International Nuclear Information System (INIS)

Krahenbuhl, M.P.; Slaughter, D.M.

1998-01-01

The aim of this paper is to clearly define the chemical and nuclear principles governing Fission Track Analysis (FTA) to determine environmental levels of 239 Pu in urine. The paper also addresses deficiencies in FTA methodology and introduces improvements to make FTA a more reliable research tool. Our refined methodology, described herein, includes a chemically-induced precipitation phase, followed by anion exchange chromatography and employs a chemical tracer, 236 Pu. We have been able to establish an inverse correlation between Pu recovery and sample volume and our data confirms that increases in sample volume do not result in higher accuracy or lower detection limits. We conclude that in subsequent studies, samples should be limited to approximately two liters. The Pu detection limit for a sample of this volume is 2.8 μBq/l. (author)

CR-39 as induced track detector in reactor: irradiation effect

International Nuclear Information System (INIS)

Zylberberg, H.

1989-07-01

A systematic study about reactor's neutrons radiation effect and gamma radiation effect on the properties of CR-39 that are significant for its use as induced fission track detector is showed. The following studies deserved attention: kinetics of the fission track chemical development; efficiency to register and to develop fission track; losses of developable tracks; variation in the number of developable tracks and variation in the visible and ultraviolet radiation spectrum. The dissertation is organized in seven specific chapters: solid state nuclear tracks (SSNT); CR-39 as SSNT; objectives and problems presentation; preparation and characterization of CR-39 as SSNT; gamma irradiation effect on the properties of CR-39 as SSNT; reactor neutron irradiation effect on the properties of CR-39 as SSNT and, results discussions and conclusions. The main work contributions are the use of CR-39 in the determination of fissionable nuclide as thorium and uranium in solid and liquid samples; gamma radiation damage on CR-39 as well as the reactor's neutron damage on CR-39. (B.C.A.) 62 refs, 53 figs, 21 tabs

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 ...

An international research project on Armenian archaeological sites: fission-track dating of obsidians

Energy Technology Data Exchange (ETDEWEB)

Badalian, R.; Bigazzi, G. E-mail: g.bigazzi@iggi.pi.cnr.it; Cauvin, M.-C.; Chataigner, C.; Jrbashyan, R.; Karapetyan, S.G.; Oddone, M.; Poidevin, J.-L

2001-06-01

In the Mediterranean and adjacent regions, the Caucasus is one of the less studied areas in relation to provenance studies of prehistoric obsidian artefacts. In the frame of an international INTAS research project, an extensive surveying and sampling campaign was carried out in the numerous obsidian bearing volcanic complexes of Armenia. 33 obsidian samples were analysed using the fission-track dating method in order to characterise the potential sources of the numerous artefacts found in prehistoric sites. Ages cluster into five groups--Upper Neopleistocene Q{sub III}, Middle Neopleistocene Q{sub II}, Lower Neopleistocene Q{sub I}, Lower Eopleistocene Q{sub EI} and Lower Pliocene N{sub 3}{sup 1} groups. This research represents a significant contribution to a better knowledge of chronology of Armenian volcanism for which only few data were available. The resulting data-set appears to be a solid base for future provenance studies.

Thermal and tectonic history of the Barrandian Lower Paleozoic, Czech Republic: is there a fission-track evidence for Carboniferous-Permian overburden and pre-Westphalian alpinotype thrusting? (Critical comments on the paper by Ulrich Mann and Günter A. Wagner)

Czech Academy of Sciences Publication Activity Database

Filip, Jiří; Suchý, V.

2004-01-01

Roč. 79, č. 2 (2004), s. 107-112 ISSN 1214-1119 R&D Projects: GA AV ČR(CZ) IAA3012703 Grant - others:DFG(DE) Ma 1861/1-1 Keywords : apatite fission-track analysis * Barrandian * Variscan Orogeny Subject RIV: DB - Geology ; Mineralogy http://www.geology.cz/bulletin/contents/2004/vol79no2/bullgeosci200402107.pdf

Tracking the multi-stage exhumation history of the western Chinese Tianshan by Apatite Fission Track (AFT) dating - Implications for the preservation of epithermal deposits in ancient orogenic belt

Science.gov (United States)

Wang, Yannan; Cai, Keda

2017-04-01

The western Chinese Tianshan, located in the southern domain of the Central Asian Orogenic Belt (CAOB), was originally constructed by multiple accretion-collision processes in the Paleozoic, and was superimposed by complex intracontinental tectonic evolution in the Mesozoic-Cenozoic. Understanding the timing and mechanism of the latter geological processes is critical to unravel the preservation conditions of the epithermal deposits in the western Chinese Tianshan. This work presents new apatite fission track (AFT) data for three mountain ranges of the western Chinese Tianshan to track their exhumation history. Our AFT data gave a wide range of ages from 76.8 ± 5.5 Ma to 182.3 ± 9.9 Ma, and the mean confined fission track lengths are between 9.8 ± 0.5 μm and 12.3 ± 0.2 μm. The new data, in combination with the thermal history modeling，enable us to attribute the exhumation history to three primary stages, including Early Permian (300-280 Ma), Late Triassic-Early Cretaceous (230-130 Ma), and Late Oligocene-Early Miocene (30-20 Ma). The first stage may be caused by the terrane accretion-collision in the late Paleozoic. The second stage was likely related to the closure of the Mongol-Okhotsk Ocean during the Mesozoic. The last one is regarded as the result of the collision between the Indian Plate and the Eurasia Plate in the Cenozoic. The extraordinary exhumation processes of these three major mountain ranges might have been responsible for sediment supply to the corresponding intra-mountain basins in the western Chinese Tianshan, and the particularly mountain-basin coupling evolution is ascribed to an essential condition for the preservation of epithermal deposits in ancient orogenic belt.

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)

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

Study of uranium mineralization in rock samples from marwat range bannu basin by fission track analysis technique

International Nuclear Information System (INIS)

Qureshi, A.Z.; Ullah, K.; Ullah, N.; Akram, M.

2004-07-01

The Geophysics Division, Atomic Energy Minerals Centre (AEMC), Lahore has planned a uranium exploration program in Marwat Range, Bannu Basin. In this connection 30 thin sections of rock samples, collected from four areas; namely, Darra Tang, Simukili, Karkanwal and Sheikhillah from Marwat Range, and one from Salt Range were provided to Nuclear Geology Group of Physics Research Division, PINSTECH for the study of nature and mechanism of uranium mineralization These studies are aimed to help in designing uranium exploration strategy by providing the loci of uranium sources in the Marwat and Salt Ranges. The samples have been studied using fission track analysis technique. (author)

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

Energy Technology Data Exchange (ETDEWEB)

Yadav, J.R., E-mail: yadav_jogendra@rediffmail.co [Health Physics Laboratory, Health Physics Division, BARC, Tarapur 401502 (India); Rao, D.D.; Kumar, Ranjeet [Health Physics Laboratory, Health Physics Division, BARC, Tarapur 401502 (India); Aggarwal, S.K. [Fuel chemistry Division, BARC, Trombay, Mumbai 400085 (India)

2011-07-15

Fission track analysis (FTA) technique for the determination of {sup 239}Pu excreted through urine has been standardized using blank samples, tracer and {sup 239}Pu spikes. Double stage anion exchange separation protocol has been applied and an average radiochemical recovery of {sup 239}Pu of 18% was obtained. An average track registration efficiency of 11 tracks per {mu}Bq of {sup 239}Pu, irradiated to 0.35x10{sup 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 34 {mu}Bq L{sup -1} of urine sample was obtained and will be useful for monitoring chronic exposure cases handling MOX fuel.

Photofission observations in reactor environments using selected fission-product yields

International Nuclear Information System (INIS)

Gold, R.; Ruddy, F.H.; Roberts, J.H.

1982-01-01

A new method for the observation of photofission in reactor environments is advanced. It is based on the in-situ observation of fission product yield. In fact, at a given in-situ reactor location, the fission product yield is simply a weighted linear combination of the photofission product yield, Y/sub gamma/, and the neutron induced fission product yield, Y/sub n. The weight factors arising in this linear combination are the photofission fraction and neutron induced fission fraction, respectively. This method can be readily implemented with established techniques for measuring in-situ reactor fission product yield. For example, one can use the method based on simultaneous irradiation of radiometric (RM) and solid state track recorder (SSTR) fission monitors. The sensitivity and accuracy and current knowledge of fission product yields. Unique advantages of this method for reactor applications are emphasized

Neutron emission as a probe of fusion-fission and quasi-fission dynamics

International Nuclear Information System (INIS)

Hinde, D.J.

1991-01-01

Pre- and post scission neutron yeilds have been measured as a function of projectile mass, compound nucleus fissility, and fission mass-split and total kinetic energy (TKE) for 27 fusion-fission and quasi-fission reactions induced by beams of 16,18 O, 40 Ar and 64 Ni. A new method of interpretation of experimental pre-scission neutron multiplicities ν-pre and mean kinetic energies ε ν allows the extraction of fission time scales with much less uncertainty than previously, all fusion-fission results being consistent with a dynamical time scale of (35±15) x 10 -21 s for symmetric fission. All reactions show that ν-pre falls quite rapidly with increasing mass-asymmetry; evidence is presented that for fusion-fission reactions this is partly due to a reduction of the dynamical fission time scale with mass-asymmetry. For quasi-fission, the data indicate that the pre-scission multiplicity and mean neutron kinetic energy are very sensitive to the final mass-asymmetry, but that the time scale is virtually independent of mass-asymmetry. It is concluded that for fusion-fission there is no dependence of ν-pre on TKE, whilst for 64 Ni-induced quasi-fission reactions, a strong increase of ν-pre with decreasing TKE is observed, probably largely caused by neutron emission during the acceleration time of the fission fragments in these fast reactions. Interpretation of post-scission multiplicities in terms of fragment excitation energies leads to deduced time scales consistent with those determined from the pre-scission data. 54 refs., 17 tabs., 25 figs

A criticism of the paper entitled 'A practical method of estimating standard error of the age in the Fission Track Dating method' by Johnson, McGee and Naeser

International Nuclear Information System (INIS)

Green, P.F.

1981-01-01

It is stated that the common use of Poissonian errors to assign uncertainties in fission-track dating studies has led Johnson, McGee and Naeser (1979) to the mistaken assumption that such errors could be used to measure the spatial variation of track densities. The analysis proposed by JMN 79, employing this assumption, therefore leads to erroneous assessment of the error in an age determination. The basis for the statement is discussed. (U.K.)

Fission of intermediate mass nuclei by photons of stopping radiation in the maximum energy range 0,8 - 1,8 MeV

International Nuclear Information System (INIS)

Lima, D.A. de.

1983-07-01

The fission of intermediate mass nuclei in Al - Ta interval, induced by stopping radiation phtons of maximum energies between 0,8 and 1.8 GeV is studied. Nd and Sm thin targets and Al, Ti, Co, Zr, Nb, Ag, In and Ta thick targets were used, considering all peculiarities inherent to absorption of fission fragments in the target. The samples were exposed into the 2.5 GeV Electron Synchrotron in Bonn Univerity. The fission fragment tracks were registered in foil type detectors using mica muscovite for Sm and Nd, CR-39 for Al and Ti and makrofol for Co, Zr; Nb, Ag, In, Nd and Ta. The track length and track depth angle distributions were measured for determining fission efficiencies. The fission cross sections and nuclear fissionable of the studied elements were evaluated. (M.C.K.) [pt

New insight on the high radiation resistance of UO{sub 2} against fission fragments

Energy Technology Data Exchange (ETDEWEB)

Szenes, G., E-mail: szenesgyorgy@caesar.elte.hu

2016-12-15

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, S{sub et} = 20 keV/nm is high in semiconducting UO{sub 2} 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 CeO{sub 2} are discussed. It is verified that sputtering is described accurately by the Arrhenius equation for various materials including UO{sub 2}. The ion-induced surface potential has a strong effect on the activation energy. - Highlights: • Uniform features of track formation are demonstrated. • Semiconductors are more stable than insulators against fission fragments. • Melting point and width of the thermal spike control the track size. • High threshold for tracks S{sub et} = 20 keV/nm for fission fragments in semiconducting UO{sub 2}. • An Arrhenius equation describes the inelastic sputtering in UO{sub 2} and other solids.

Determination Of Uranium Concentration In Teeth Female Samples Using Fission Tracks In CR-39 From Different Countries

International Nuclear Information System (INIS)

Hummadi, S.S

2010-01-01

The present study was under taken to measure the uranium concentration in female teeth samples collected from different nationalities.The determination of uranium concentration in these samples has been done by using CR-39 track detector.The nuclear reaction is used as a source of nuclear fission fragments is (n, f) obtained by the bombardment of U-235 with thermal neutrons with flux (5*10 3 n/cm 2 .s) was used from (Am-Be) neutron source.The obtained results show the concentration is ranging from (0.58±0.7ppm) in Oman and Uae to (0.35±0.03ppm)in Iraqi for male, the uranium concentration was the highest in Oman and Uae for female

Unstable isotopes in a stable landscape?- Untangling Southern Africa's geological history with fission tracks and cosmogenic nuclides

International Nuclear Information System (INIS)

Belton, D.; Brown, R.; Fink, D.

1998-01-01

Full text: In the absence of direct evidence for burial and subsequent exposure of the land surface in the interior of Africa, researchers have argued for surface ages of several hundred million years. The proposition that landforms may have persisted at the surface for these extensive periods of time has a number of important implications. It suggests that the processes of tectonics and geomorphic evolution have been essentially absent for a period of up to 500 Ma. As a consequence, the persistence of these landscapes would require extremely low rates of weathering and erosion. Although this view of continental evolution has been widely held for several decades, recent studies suggest that continental interiors in Africa, Australia, Brazil and north America, have been subject to denudation in the order of several kilometres during the last 60 Ma. This study applies the complimentary techniques of apatite fission track and cosmogenic nuclide analysis, in an effort to measure both the long-term crustal-scale denudation and the short-term erosion rates, of which denudation is a function. We present preliminary data from the Zimbabwe Craton that illustrates the utility of such techniques in addressing both local and regional geological questions. The study provides a detailed picture of complex tectonic responses as well as large scale denudation over extended periods of time

Alkaline glass as induced fission fragment detectors

International Nuclear Information System (INIS)

Amorim, A.M.M.

1986-01-01

The slide glass, registered trade marks INLAB, INVICT and PERFECTA were compared. For the three kinds of glasses the following studies were done: chemical composition; general dissolution rate for hydrofluoric acid solutions of concentrations between 1 and 10M, at 30 0 C and ultrasound shaking; relative efficiency for recording fission fragment tracks from 252 Cf. The INLAB glass was selected due to the better quality of its surface after chemical etching. The HF concentration 2.5M was determined for chemical etching of INLAB glass, and the optimum etching time was chosen between 8 and 10 minutes. The thermal attenuation of latent tracks in the environmental temperature was observed for intervals uo to 31 days between the detector exposure to the fission fragment source and etching of tracks. Several methods were used for determining the detector parameters, such as: critical angle, angle of the cone and efficiency of etching. The effects of gamma irradiation from 60 Co and reactor neutrons in material properties as track detector were studied. Attenuation of latent tracks and saturation of color centers were observed for doses over 100M Rad. Since this kind of material contains uranium as impurity, uniformely distributed, slide glass were calibrated to be applied as a monitor of thermal neutron flux in nuclear reactor. (Author) [pt

The analysis of projected fission track lengths

International Nuclear Information System (INIS)

Laslett, G.M.; Galbraith, R.F.; Green, P.F.

1994-01-01

This article deals with the question of how features of the thermal history can be estimated from projected track length measurements, i.e. lengths of the remaining parts of tracks that have intersected a surface, projected onto that surface. The appropriate mathematical theory is described and used to provide a sound basis both for understanding the nature of projected length measurements and for analysing observed data. The estimation of thermal history parameters corresponding to the current temperature, the maximum palaeotemperature and the time since cooling, is studied using laboratory data and simulations. In general the information contained in projected track lengths and angles is fairly limited, compared, for example, with that from a much smaller number of confined tracks, though we identify some circumstances when such measurements may be useful. Also it is not straightforward to extract the information and simple ad hoc estimation methods are generally inadequate. (author)

Solid state nuclear track detectors

International Nuclear Information System (INIS)

Medeiros, J.A.; Carvalho, M.L.C.P. de

1992-12-01

Solid state nuclear track detectors (SSNTD) are dielectric materials, crystalline or vitreous, which registers tracks of charged nuclear particles, like alpha particles or fission fragments. Chemical etching of the detectors origin tracks that are visible at the optical microscope: track etching rate is higher along the latent track, where damage due to the charged particle increase the chemical potential, and etching rate giving rise to holes, the etched tracks. Fundamental principles are presented as well as some ideas of main applications. (author)

Fission fragment angular distributions and fission cross section validation

International Nuclear Information System (INIS)

Leong, Lou Sai

2013-01-01

The present knowledge of angular distributions of neutron-induced fission is limited to a maximal energy of 15 MeV, with large discrepancies around 14 MeV. Only 238 U and 232 Th have been investigated up to 100 MeV in a single experiment. The n-TOF Collaboration performed the fission cross section measurement of several actinides ( 232 Th, 235 U, 238 U, 234 U, 237 Np) at the n-TOF facility using an experimental set-up made of Parallel Plate Avalanche Counters (PPAC), extending the energy domain of the incident neutron above hundreds of MeV. The method based on the detection of the 2 fragments in coincidence allowed to clearly disentangle the fission reactions among other types of reactions occurring in the spallation domain. I will show the methods we used to reconstruct the full angular resolution by the tracking of fission fragments. Below 10 MeV our results are consistent with existing data. For example in the case of 232 Th, below 10 MeV the results show clearly the variation occurring at the first (1 MeV) and second (7 MeV) chance fission, corresponding to transition states of given J and K (total spin and its projection on the fission axis), and a much more accurate energy dependence at the 3. chance threshold (14 MeV) has been obtained. In the spallation domain, above 30 MeV we confirm the high anisotropy revealed in 232 Th by the single existing data set. I'll discuss the implications of this finding, related to the low anisotropy exhibited in proton-induced fission. I also explore the critical experiments which is valuable checks of nuclear data. The 237 Np neutron-induced fission cross section has recently been measured in a large energy range (from eV to GeV) at the n-TOF facility at CERN. When compared to previous measurements, the n-TOF fission cross section appears to be higher by 5-7 % beyond the fission threshold. To check the relevance of n-TOF data, we simulate a criticality experiment performed at Los Alamos with a 6 kg sphere of 237 Np. This

Extrapolation of zircon fission-track annealing models

International Nuclear Information System (INIS)

Palissari, R.; Guedes, S.; Curvo, E.A.C.; Moreira, P.A.F.P.; Tello, C.A.; Hadler, J.C.

2013-01-01

One of the purposes of this study is to give further constraints on the temperature range of the zircon partial annealing zone over a geological time scale using data from borehole zircon samples, which have experienced stable temperatures for ∼1 Ma. In this way, the extrapolation problem is explicitly addressed by fitting the zircon annealing models with geological timescale data. Several empirical model formulations have been proposed to perform these calibrations and have been compared in this work. The basic form proposed for annealing models is the Arrhenius-type model. There are other annealing models, that are based on the same general formulation. These empirical model equations have been preferred due to the great number of phenomena from track formation to chemical etching that are not well understood. However, there are two other models, which try to establish a direct correlation between their parameters and the related phenomena. To compare the response of the different annealing models, thermal indexes, such as closure temperature, total annealing temperature and the partial annealing zone, have been calculated and compared with field evidence. After comparing the different models, it was concluded that the fanning curvilinear models yield the best agreement between predicted index temperatures and field evidence. - Highlights: ► Geological data were used along with lab data for improving model extrapolation. ► Index temperatures were simulated for testing model extrapolation. ► Curvilinear Arrhenius models produced better geological temperature predictions

Uranium content and fission track ages of some basalts from the FAMOUS area

International Nuclear Information System (INIS)

Storzer, Dieter; Selo, Madeleine

1976-01-01

The uranium contents of basalts from the rift valley in the Atlantic ocean near 37 deg N range between 75 ppb and 450 ppb. The fission track ages of these basalts range between 3x10 3 years and 6x10 5 years. They increase with distance from the axis of the median valley. Therefore, the locus of accretion of new crust seems to be restricted to a relatively narrow zone along the valley floor. In addition, the ages indicate that during the last 10 5 years the rate of accretion has been slower to the west than to the east. This indicates a migration of the active spreading center to the west by at least 1 km. the sea-floor spreading rates are high, up to 9cm/year, near the center of actual magmatic activity. They decrease with distance from the valley axis to 0.7 cm/year at about 2 km in the west respectively 1.5 cm/year at about 4 km in the east

Annealing behavior of alpha recoil tracks in phlogopite

International Nuclear Information System (INIS)

Gao Shaokai; Yuan Wanming; Dong Jinquan; Bao Zengkuan

2005-01-01

Alpha recoil tracks (ARTs) formed during the a-decay of U, Th as well as their daughter nuclei are used as a new dating method which is to some extent a complementarity of fission track dating due to its ability to determine the age of young mineral. ARTs can be observable under phase-contrast interference microscope through chemical etching. In order to study the annealing behavior of ARTs in phlogopite, two methods of annealing experiments were executed. Samples were annealed in the electronic tube furnace at different temperatures ranging from 250 degree C to 450 degree C in steps of 50 degree C. For any given annealing temperature, different annealing times were used until total track fading were achieved. It is found that ARTs anneal much more easily than fission tracks, the annealing ratio increase non-linearly with annealing time and temperature. Using the Arrhenius plot, an activation energy of 0.68ev is finally found for 100% removal of ARTs, which is less than the corresponding value for fission tracks (FTs). Through extending the annealing time to geological time, a much lower temperature range of the sample's cooling history can be got.

Fission/milligram of 235U in BIG-10 Tests A, C, E, and B

International Nuclear Information System (INIS)

Gilliam, D.M.; Grundl, J.A.; Hansen, G.E.

1976-01-01

The entire series of dosimetry foil tests at BIG-10 (including the preliminary Test A, five fission foil set irradiations--Tests C, five non-fission foil set irradiations--Tests E, and five track-etch detector irradiations--Tests B) were monitored continuously by the NBS double fission chamber PP5 in the central test cavity. The accuracy of the absolute fission counting data (fissions/milligram of 235 U) is estimated to be 1.4% for Tests A, C, and E and 1.5% for Test B. Deposit mass assay uncertainties remain the dominant error

Isotopic Determination of Nuclear Materials Using Nuclear Fission Track Registration Technique and Thermal Ionization Mass Spectrometric Technique

International Nuclear Information System (INIS)

Jeon, Young Sin; Pyo, Hyeong Yeol; Park, Yong Joon; Song, Kyu Seok; Kim, Won Ho; Jee, Kwang Yong

2007-05-01

It is very important to develope the technology for the determination of isotopic ratios of hot particles( 234 U, 235 U, 236 U etc.) detected from swipe samples of various nuclear facilities. This technology is highly competitive internationally and has to be established independently as long as our government maintains atomic energy and treats nuclear materials. In this text, sample pretreatment procedure, gamma-ray counting, alpha or fission track techniques, isotopic analysis of U and Pu, background problems and detection limits for mass determination, and their application to the real swipe sample were described with detailed procedure. This technology would contribute to the Korean economy's high growth rate as well as to superiority of government's leading research and development programs if successfully established

Imprints left by natural radioactivity in geological materials: uranium fission tracks and thermoluminescence applications in earth sciences

International Nuclear Information System (INIS)

Broquet, P.; Chambaudet, A.; Rebetez, M.; Charlet, J.M.

1994-01-01

In a rock, all minerals which contain uranium are host to a number of spontaneous fission phenomena forming a single damaged area called a ''latent track'', observations of which may lead to dating, uranium mapping and finding paleo-geo-thermometers (thermal history, used in oil exploration). The radioactive elements during the decay process release energy which is trapped as electrons into the physical or chemical defects of the crystalline lattice; this energy can be later released by heating the mineral (thermic stimulated luminescence); the thermoluminescence is characterized by a glow which spectrum constitutes a typical feature of the mineral, its crystallization conditions and the subsequent evolution of the material. Natural and induced glow curve may be produced. 6 figs., 52 refs

Annealing effects in solid-state track recorders

International Nuclear Information System (INIS)

Gold, R.; Roberts, J.H.; Ruddy, F.H.

1981-01-01

Current analyses of the annealing process in Solid State Track Recorders (SSTR) reveal fundamental misconceptions. The use of the Arrhenius equation to describe the decrease in track density resulting from annealing is shown to be incorrect. To overcome these deficiencies, generalized reaction rate theory is used to describe the annealing process in SSTR. Results of annealing experiments are used to guide this theoretical formulation. Within this framework, the concept of energy per etchable defect for SSTR is introduced. A general correlation between sensitivity and annealing susceptibility in SSTR is deduced. In terms of this general theory, the apparent correlation between fission track size and fission track density observed under annealing is readily explained. Based on this theoretical treatment of annealing phenomena, qualitative explanations are advanced for current enigmas in SSTR cosmic ray work

Reliable method for fission source convergence of Monte Carlo criticality calculation with Wielandt's method

International Nuclear Information System (INIS)

Yamamoto, Toshihiro; Miyoshi, Yoshinori

2004-01-01

A new algorithm of Monte Carlo criticality calculations for implementing Wielandt's method, which is one of acceleration techniques for deterministic source iteration methods, is developed, and the algorithm can be successfully implemented into MCNP code. In this algorithm, part of fission neutrons emitted during random walk processes are tracked within the current cycle, and thus a fission source distribution used in the next cycle spread more widely. Applying this method intensifies a neutron interaction effect even in a loosely-coupled array where conventional Monte Carlo criticality methods have difficulties, and a converged fission source distribution can be obtained with fewer cycles. Computing time spent for one cycle, however, increases because of tracking fission neutrons within the current cycle, which eventually results in an increase of total computing time up to convergence. In addition, statistical fluctuations of a fission source distribution in a cycle are worsened by applying Wielandt's method to Monte Carlo criticality calculations. However, since a fission source convergence is attained with fewer source iterations, a reliable determination of convergence can easily be made even in a system with a slow convergence. This acceleration method is expected to contribute to prevention of incorrect Monte Carlo criticality calculations. (author)

Progress in the application of solid-state track recorders to reactor physics experiments

International Nuclear Information System (INIS)

Besant, C.B.; Ipson, S.S.

1969-03-01

Heavily ionising particles passing through insulating materials cause tracks due to damage. These strain energy fields may be observed directly with an electron microscope or, after etching, the tracks may be seen with an optical microscope. The etching solution penetrates the damaged portion of the material and enlarges the hole if the etching is continued. This technique has been applied to detecting fission fragments from fissions taking place in a thin source of fissile material. The source, together with the insulating material is called a Solid-State Track Recorder and has been applied to the measurement of fission ratios in the fast critical assembly ZEBRA at Winfrith. The main disadvantage of the technique has been in counting tracks by eye which is laborious and subject to the human element. This has been overcome by counting tracks with a 'Quantimet' Computer Image Analyser. Absolute fission rate measurements are also discussed and it has been shown that measurements to an accuracy of better than ± 1% should be possible with this technique. (author)

Dynamic of an intra-continental orogenic prism: thermo-chronologic (apatite fission tracks) and tectonic evolution of the axial zone and the piedmont of the west-central Pyrenees

International Nuclear Information System (INIS)

Meresse, F.

2013-02-01

This work illustrates the application of thermo chronology to the study of the following geologic issue: the tectonic evolution of the Pyrenean oncologic prism. Thermo-chronology gives information on the vertical movements at the scale of geological eras. Thermo-chronology is based on the following principle: the decay of a nucleus gives birth to a daughter nucleus. Above a specific temperature named closure temperature, the daughter element can diffuse outside the system while below the closure temperature, diffusion is not possible. Consequently thermo-chronology can be considered to date the moment when a mineral goes below a a specific closure temperature. Minerals have different closure temperatures and so by using a suite of thermo-chronometers on a single sample, its cooling path through the crust can be reconstructed. This work focuses on apatite fission track (AFT)analysis which is a low temperature thermo-chronometer. In apatites the temperature range between 60 and 120 Celsius degrees corresponds to the partial annealing zone. The spontaneous fission of one U 238 nucleus entails the formation of one fission track. The determination of the initial quantity of U 238 is based on the natural steady ratio U 238 /U 235 which equals 137.88. The initial quantity of U 235 is determined through the neutron irradiation of the sample. The knowledge of the initial quantity of U 238 and the number of tracks in the sample allows the dating of the sample. In this work we combine AFT thermo- chronology with a detailed structural analysis to describe vertical movements related to the thrusting system evolution, and to determine the influence of the latter on the sedimentation/burial/exhumation cycle of the syn-orogenic deposits of the southern fore-land basin

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.

Alpha and fission autoradiography of uranium rods

International Nuclear Information System (INIS)

Copic, M.; Ilicj, R.; Najzher, M.; Rant, J.

1977-01-01

Macro and micro-distribution of uranium minerals in ore bodies are investigated by alpha autoradiography and by neutron induced fission autoradiography using LR 115 solid state track detector. Optimal conditions are determined experimentally for both methods and examples presented. For field applications the alpha autoradiography (author)

Exhumation of Basement-cored Uplifts: Example of the Kyrgyz Range Quantified with Apatite Fission-track Thermochronology

Science.gov (United States)

Sobel, Edward R.; Oskin, Michael; Burbank, Douglas; Mikolaichuk, Alexander

2005-01-01

The Kyrgyz Range, the northernmost portion of the Kyrgyzstan Tien Shan, displays topographic evidence for lateral propagation of surface uplift and exhumation. The highest and most deeply dissected segment lies in the center of the range. To the east, topography and relief decrease, and preserved remnants of a Cretaceous regional erosion surface imply minimal amounts of bedrock exhumation. The timing of exhumation of range segments defines the lateral propagation rate of the range-bounding reverse fault and quantifies the time and erosion depth needed to transform a mountain range from a juvenile to a mature morphology. New apatite fission-track (AFT) data from three transects from the eastern Kyrgyz Range, combined with published AFT data, demonstrate that the range has propagated over 110 km eastwards over the last 7-11 Myr. Based on the thermal and topographic evolutionary history, we present a model for a time-varying exhumation rate driven by rock uplift and changes in erodability and the time scale of geomorphic adjustment to surface uplift. Easily eroded, Cenozoic sedimentary rocks overlying resistant basement control early, rapid exhumation and slow surface upliftrates. As increasing amounts of resistant basement are exposed, exhumation rates decrease while surface uplift rates are sustained or increase, thereby growing topography. As the range becomes high enough to cause ice accumulation and develop steep river valleys, fluvial and glacial erosion become more powerful and exhumation rates once again increase. Independently determined range-noma1 shortening rates have also varied over time, suggesting a feedback between erosional efficiency and shortening rate.

A new technique to measure fission-product diffusion coefficients in UO2 fuel

International Nuclear Information System (INIS)

Hocking, W.H.; Verrall, R.A.; Bushby, S.J.

1999-01-01

This paper describes a new out-reactor technique for the measurement of fission-product diffusion rates in UO 2 . The technique accurately simulates in-reactor fission-fragment effects: a thermal diffusion that is due to localized mixing in the fission track, radiation-enhanced diffusion that is due to point-defect creation by fission fragments, and bubble resolution. The technique utilizes heavy-ion accelerators - low energy (40 keV to 1 MeV) for fission-product implantation, high energy (72 MeV) to create fission-fragment damage effects, and secondary ion mass spectrometry (SIMS) for measuring the depth profile of the implanted species. Preliminary results are presented from annealing tests (not in the 72 MeV ion flux) at 1465 deg. C and 1650 deg. C at low and high concentrations of fission products. (author)

Tectonic setting and uplift analysis of the Pangani rift basin in northern Tanzania using apatite fission track thermochronology

International Nuclear Information System (INIS)

Mbede, E.I.

2001-01-01

Thirty four new Apatite Fission Track (AFT) ages and 32 track length distributions from samples of basement rocks flanking the Pangani rift, East African Rift System (EARS) are presented, in an attempt to elucidate the uplift and erosion of the rift flanks. The ages fall in the range of 207±15 to 48±4 Ma, spanning from Early Jurassic to Early Tertiary. These ages are much younger than the last thermal event in the Mozambique belt that form the basement complex and are interpreted to represent the most recent tectonic events. Track length (TL) distributions suggest that uplift and erosion of the rift flanks are related to three different tectonic events, which are also recorded by the sedimentary units within the adjacent coastal basins. These included the Triassic/Early Jurassic, Late Cretaceous and Early Tertiary tectonic events. Erosion and isostatic rebound have modified the tectonically induced topographic patterns and the highly elevated plateaus flanking the Pangani rift represent an erosional surface referred to as the 'Gondwana surface' of eastern and central Africa. T he present AFT data suggest that initial exhumation of the 'Gondwana surface' from temperatures above 383.15 K to temperatures less than 333.15 K, in this area, took place during Early Jurassic times, but the final sub-aerial exposure of the surface did not take place until Early Tertiary. (author)

Distribution of uranium in dental porcelains by means of the fission track method

International Nuclear Information System (INIS)

Shimizu, Masami; Noguchi, Kunikazu; Moriwaki, Kazunari; Sairenji, Eiko

1980-01-01

Porcelain teeth, some of which contain uranium compounds for aesthetic purpose, have been widely used in dental clinics. Hazardous effects due to uranium radiation have been suggested by recent publications. In the previous study, the authors reported the uranium content of porcelain teeth and radiation dose by it. In this study, using the fission track method, the authors examined spatial distribution of uranium in dental porcelain teeth (4 brands) which were marketed in Japan. From each sample of porcelain tooth, a 1-mm-thick specimen was sliced, and uranium content was measured at every 0.19 mm from labial side to lingual side for making a uranium distribution chart. Higher uranium concentration was found in Trubyte Bioblend porcelain teeth (USA) and they showed almost uniform distribution of uranium, while those of the Japanese three brands indicated, in most case, comparatively lower concentration and found to be non-uniform distributions. Range of uranium concentration in these brands were N.D. -- 5.2 ppm (Shofu-Ace), N.D. -- 342 ppm (Shofu-Real), N.D. -- 47 ppm (G.C. Livdent) and N.D. -- 235 ppm (Trubyte Bioblend), respectively. (author)

Fission times of excited nuclei: An experimental overview

International Nuclear Information System (INIS)

Morjean, M.; Morjean, M.; Jacquet, D.

2009-01-01

An overview of selected recent experimental results on fission times is presented. Evidences for over-damped motion up to saddle point during the fission process of highly excited nuclei have been obtained independently through fission probability, pre-scission multiplicity and direct time measurements. In addition, strong clues have been found for a temperature dependency of friction. Experiments probing transient effects through fission probabilities are presented and the counterbalanced effects of friction and level density parameters are discussed. Promising perspectives for super-heavy stability studies, based on fission time measurements, are presented. (authors)

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 its 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 its 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.

Radiochemistry and the Study of Fission

International Nuclear Information System (INIS)

Rundberg, Robert S.

2016-01-01

These are slides from a lecture given at UC Berkeley. Radiochemistry has been used to study fission since its 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 its 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.

Pion-induced fission of 209Bi and 119Sn: measurements, calculations, analyses and comparison

International Nuclear Information System (INIS)

Rana, M.A.; Sher, G.; Manzoor, S.; Shehzad, M.I.

2011-01-01

Cross-sections for the π - -induced fission of 209 Bi and 119 Sn have been measured using the most sensitive CR-39 solid-state nuclear track detector. In experiments, target–detector stacks were exposed to negative pions of energy 500, 672, 1068, and 1665 MeV at the Brookhaven National Laboratory, USA. An important aspect of the present paper is the comparison of pion-induced fission fragment spectra of above mentioned nuclei with the spontaneous fission fragment spectra of 252 Cf. This comparison is made in terms of fission fragment track lengths in the CR-39 detectors. Measurement results are compared with calculations of Monte Carlo and statistical weight functions methods using the computer code CEM95. Agreement between measurements and calculations is fairly good for 209 Bi target nuclei whereas it is indigent for the case of 119 Sn. The possibilities of the trustworthy calculations, using the computer code CEM95, comparable with measurements of pion-induced fission in intermediate and heavy nuclei are explored by employing various systematics available in the code. Energy dependence of pion-induced fission in 119 Sn and 209 Bi is analyzed employing a newly defined parameter geometric-size-normalized fission cross-section (χ f g ). It is found that the collective nuclear excitations, which may lead to fission, become more probable for both 209 Bi and 119 Sn nuclei with increasing energy of negative pions from 500 to 1665 MeV. (author)

Fission theory and actinide fission data

Energy Technology Data Exchange (ETDEWEB)

Michaudon, A.

1975-06-01

The understanding of the fission process has made great progress recently, as a result of the calculation of fission barriers, using the Strutinsky prescription. Double-humped shapes were obtained for nuclei in the actinide region. Such shapes could explain, in a coherent manner, many different phenomena: fission isomers, structure in near-threshold fission cross sections, intermediate structure in subthreshold fission cross sections and anisotropy in the emission of the fission fragments. A brief review of fission barrier calculations and relevant experimental data is presented. Calculations of fission cross sections, using double-humped barrier shapes and fission channel properties, as obtained from the data discussed previously, are given for some U and Pu isotopes. The fission channel theory of A. Bohr has greatly influenced the study of low-energy fission. However, recent investigation of the yields of prompt neutrons and γ rays emitted in the resonances of {sup 235}U and {sup 239}Pu, together with the spin determination for many resonances of these two nuclei cannot be explained purely in terms of the Bohr theory. Variation in the prompt neutron and γ-ray yields from resonance to resonance does not seem to be due to such fission channels, as was thought previously, but to the effect of the (n,γf) reaction. The number of prompt fission neutrons and the kinetic energy of the fission fragments are affected by the energy balance and damping or viscosity effects in the last stage of the fission process, from saddle point to scission. These effects are discussed for some nuclei, especially for {sup 240}Pu.

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.

New insights on the geological evolution of the continental margin of Southeastern 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

2017-04-01

New insights on the geological evolution of the continental margin of Southeastern Brazil derived from zircon and apatite (U-Th-Sm)/He and fission-track data Krob, F.C.1, Stippich, C. 1, Glasmacher, U.A.1, Hackspacher, P.C.2 (1) Institute of Earth Sciences, Research Group Thermochronology and Archaeometry, Heidelberg University, INF 234, 69120, Heidelberg, Germany (2) Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista, Av. 24-A, 1515 Rio Claro, SP, 13506-900, Brazil 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

The Carboniferous to Jurassic evolution of the pre-Alpine basement of Crete: Constraints from U-Pb and U-(Th)-Pb dating of orthogneiss, fission-track dating of zircon, structural and petrological data

Czech Academy of Sciences Publication Activity Database

Romano, S. S.; Brix, M. R.; Dörr, K.; Fiala, Jiří; Krenn, E.; Zulauf, G.

2006-01-01

Roč. 260, - (2006), s. 69-90 ISSN 0375-6440 Institutional research plan: CEZ:AV0Z30130516 Keywords : tectonic-evolution * Carboniferous * Jurassic * uranium-lead-dating * orthogneiss * fission-track-dating * zircon * structural-geology * petrology * metamorphism * high-temperature Subject RIV: DB - Geology ; Mineralogy

Solid State Track Recorder fission rate measurements in low power light water reactor pressure vessel mockups

International Nuclear Information System (INIS)

Ruddy, F.H.; Roberts, J.H.; Kellogg, L.S.

1985-01-01

The results of extensive SSTR measurements made at the Pool Critical Assembly (PCA) facility at Oak Ridge National Laboratory have been reported previously. Measurements were made at key locations in PCA which is an idealized mockup of the water gap, thermal shield, pressure vessel geometry of a light water reactor. Recently, additional SSTR fission rate measurements have been carried out for 237-Np, 238-U, and 235-U in key locations in the NESTOR Shielding and Dosimetry Improvement Program (NESDIP) mockup facility located at Winfrith, England. NESDIP is a replica of the PCA facility, and comparisons will be made between PCA and NESDIP measurements. The results of measurements made at the engineering mockup at the VENUS critical assembly at CEN/SCK, Mol, Belgium will also be reported. Measurements were made at selected radial and azimuthal locations in VENUS, which models the in-core and near-core regions of a pressurized water reactor. Comparisons of absolute SSTR fission rates with absolute fission rates made with the Mol miniature fission chamber will be reported. Absolute fission rate comparisons have also been made between the NBS fission chamber, radiometric fission foils, and SSTRs, and these results will be summarized

SSNTD study of the probable influence of alpha activity on the mass distribution of sup 2 sup 5 sup 2 Cf fission fragments

CERN Document Server

Paul, D; Sastri, R C; Ghose, D

1999-01-01

The SSNTD has come a long way in its application for the study of nuclear phenomena. Spontaneous fission of transuranic elements is one such phenomena wherein use of SSNTD offers easy registration of the signature of the fission fragments. The object of the present study is to explore whether any one of the track parameters such as the diameter can be used to estimate the atomic mass ratios of the spontaneous fission fragments. The spontaneous fission data from sup 2 sup 5 sup 2 Cf recorded almost at the end of one and four half-life periods for alpha decay are analysed, taking a plot of the number of tracks versus the track diameter. From these plots it is seen that initially, when significant alpha activity of sup 2 sup 5 sup 2 Cf persists, the fission fragments appear to cluster into two predominant groups as indicated by two peaks. The ratio of the diameters at these peak positions appear to be related to the ratio of average mass numbers of the light and heavy groups of fission fragments. However, absenc...

I. Fission Probabilities, Fission Barriers, and Shell Effects. II. Particle Structure Functions

Energy Technology Data Exchange (ETDEWEB)

Jing, Kexing [Univ. of California, Berkeley, CA (United States)

1999-05-01

In Part I, fission excitation functions of osmium isotopes ^{185,186, 187, 189} Os produced in ³He +^{182,183, 184, 186}W reactions, and of polonium isotopes ^{209,210, 211, 212}Po produced in ³He/⁴He + ^{206, 207, 208}Pb reactions, were measured with high precision. These excitation functions have been analyzed in detail based upon the transition state formalism. The fission barriers, and shell effects for the corresponding nuclei are extracted from the detailed analyses. A novel approach has been developed to determine upper limits of the transient time of the fission process. The upper limits are constrained by the fission probabilities of neighboring isotopes. The upper limits for the transient time set with this new method are 15x 10^–21 sec and 25x 10^–21 sec for 0s and Po compound nuclei, respectively. In Part II, we report on a search for evidence of the optical modulations in the energy spectra of alpha particles emitted from hot compound nuclei. The optical modulations are expected to arise from the ~-particle interaction with the rest of the nucleus as the particle prepares to exit. Some evidence for the modulations has been observed in the alpha spectra measured in the 3He-induced reactions, ³He + ^natAg in particular. The identification of the modulations involves a technique that subtracts the bulk statistical background from the measured alpha spectra, in order for the modulations to become visible in the residuals. Due to insufficient knowledge of the background spectra, however, the presented evidence should only be regarded as preliminary and tentative.

Influence of tracks densities in solid state nuclear track detectors

International Nuclear Information System (INIS)

Guedes O, S.; Hadler N.; Lunes, P.; Saenz T, C.

1996-01-01

When Solid State Nuclear Track Detectors (SSNTD) is employed to measure nuclear tracks produced mainly by fission fragments and alpha particles, it is considered that the tracks observation work is performed under an efficiency, ε 0 , which is independent of the track density (number of tracks/area unit). There are not published results or experimental data supporting such an assumption. In this work the dependence of ε 0 with track density is studied basing on experimental data. To perform this, pieces of CR-39 cut from a sole 'mother sheet' were coupled to thin uranium films for different exposition times and the resulting ratios between track density and exposition time were compared. Our results indicate that ε 0 is constant for track densities between 10 3 and 10 5 cm -2 . At our etching conditions track overlapping makes impossible the counting for densities around 1.7 x 10 5 cm -2 . For track densities less than 10 3 cm -2 , ε 0 , was not observed to be constant. (authors). 4 refs., 2 figs

Uranium content of coal ashes from Southern Brazil coal fueled power stations, by the fission track registration technique

International Nuclear Information System (INIS)

Morales, R.K.

1981-01-01

The feasibility of the application of the fission track registration technique for the determination of uranium in coal ashes was shown. The wet method was employed using as detector the Makrofol KG=10 μm, manufactured by Bayer. The coal ashes were originated from coal-fueled power stations localized in Southern Brazil. The results obtained ranged from 10 to 27 mg U/kg. Since the total error variation was from 18,4% to 23,8%, the method used was considered excellent. The determination of the uranium content in coal ashes is of considerable interest in environmental control in power stations, in their vicinity and wherever these ashes are used or stored. The technique used is the work proved to be very appropriate for the purpose aimed at. (Author) [pt

Geochronology and geochemistry by nuclear tracks method: some utilization examples in geologic applied

International Nuclear Information System (INIS)

Poupeau, G.; Soliani Junior, E.

1988-01-01

This article discuss some applications of the 'nuclear tracks method' in geochronology, geochemistry and geophysic. In geochronology, after rapid presentation of the dating principles by 'Fission Track' and the kinds of geological events mensurable by this method, is showed some application in metallogeny and in petroleum geolocy. In geochemistry the 'fission tracks' method utilizations are related with mining prospecting and uranium prospecting. In geophysics an important application is the earthquake prevision, through the Ra 222 emanations continous control. (author) [pt

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

International Nuclear Information System (INIS)

Shen Chuanbo; Mei Lianfu; Xu Sihuang

2009-01-01

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 ∼100 and ∼70 Ma, (2) following by a period of relative thermal stability phase between ∼70 and ∼15 Ma, (3) and then a new rapid cooling stage after ∼15 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.

Summary of theory and techniques, sample selection and project organization for potassium-argon, rubidium-strontium and fission track dating and strontium isotope studies

International Nuclear Information System (INIS)

Adams, C.J.; Graham, I.J.; Seward, D.

1987-02-01

A brief outline is given of the theory and techniques of the potassium-argon, rubidium-strontium and fission-track dating methods and related isotope studies which are currently in use at the Institute of Nuclear Sciences, DSIR. Some limitations of each technique are set out in terms of age range and materials for dating, and the appropriate choice of various mineral and rock types and subsequent age interpretations are discussed. The organisation of project proposals and categories is described and procedures for sample submission and documentation are given

RIBD-IRT, Isotope Buildup and Isotope Decay from Fission Source

International Nuclear Information System (INIS)

1990-01-01

1 - Description of problem or function: RIBD-IRT calculates isotopic concentrations resulting from two fission sources with normal down- chain decay by beta emission and isomeric transfers and inter-chain coupling resulting from (n,gamma) reactions. Calculations can be made to follow an irradiation history through an unlimited number of step changes of unrestricted duration and variability including shutdown periods, restarts at different power levels and/or any other level changes. In addition, the program permits to track and modify the concentration of individual elements as they decay with time following reactor shutdown. Tracking individual elements enables one to estimate time-dependent source terms for a hypothetical LOCA based on known or postulated fission product release mechanisms. 2 - Method of solution: RIBD-IRT is a grid processor. It organizes the various members described by the fission product library data into a grid with the various linkages established from chain branching data, yield data, and neutron capture cross sections with their branching ratios. Radioactive decay includes not only the simple member-to-member cascade but also the more complex forms where branching may be partially or completely skip one or two intervening members

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.

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

International Nuclear Information System (INIS)

Bigazzi, G.; Hadler Neto, J.C.; Iunes, P.J.; Osorio Araya, A.M.

2005-01-01

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, ∼0.2Ma old (2) intermediate-age obsidians, ∼0.4-∼0.8Ma old, and (3) older obsidians, ∼1.4-∼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

Monte-Carlo Generation of Time Evolving Fission Chains

Energy Technology Data Exchange (ETDEWEB)

Verbeke, Jerome M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kim, Kenneth S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Prasad, Manoj K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Snyderman, Neal J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2013-08-01

About a decade ago, a computer code was written to model neutrons from their “birth” to their final “death” in thermal neutron detectors (³He tubes): SrcSim had enough physics to track the neutrons in multiplying systems, appropriately increasing and decreasing the neutron population as they interacted by absorption, fission and leakage. The theory behind the algorithms assumed that all neutrons produced in a fission chain were all produced simultaneously, and then diffused to the neutron detectors. For cases where the diffusion times are long compared to the fission chains, SrcSim is very successful. Indeed, it works extraordinarily well for thermal neutron detectors and bare objects, because it takes tens of microseconds for fission neutrons to slow down to thermal energies, where they can be detected. Microseconds are a very long time compared to the lengths of the fission chains. However, this inherent assumption in the theory prevents its use to cases where either the fission chains are long compared to the neutron diffusion times (water-cooled nuclear reactors, or heavily moderated object, where the theory starts failing), or the fission neutrons can be detected shortly after they were produced (fast neutron detectors). For these cases, a new code needs to be written, where the underlying assumption is not made. The purpose of this report is to develop an algorithm to generate the arrival times of neutrons in fast neutron detectors, starting from a neutron source such as a spontaneous fission source (²⁵²Cf) or a multiplying source (Pu). This code will be an extension of SrcSim to cases where correlations between neutrons in the detectors are on the same or shorter time scales as the fission chains themselves.

Efficiency calibration of solid track spark auto counter

International Nuclear Information System (INIS)

Wang Mei; Wen Zhongwei; Lin Jufang; Liu Rong; Jiang Li; Lu Xinxin; Zhu Tonghua

2008-01-01

The factors influencing detection efficiency of solid track spark auto counter were analyzed, and the best etch condition and parameters of charge were also reconfirmed. With small plate fission ionization chamber, the efficiency of solid track spark auto counter at various experiment assemblies was re-calibrated. The efficiency of solid track spark auto counter at various experimental conditions was obtained. (authors)

Resolving the age of the first-order topography of southern Africa: new insight from joint (U-Th)/He and fission track dating of samples from deep boreholes

Science.gov (United States)

Beucher, R.; Brown, R. W.; Persano, C.; Stuart, F.; Gallagher, K.

2011-12-01

and to quantify the dispersion of single crystal ages. The shallowest borehole is 0.8 km and the deepest is 1.6, with most of them deeper than one kilometer. A spatial pattern is clearly evidenced with boreholes located above the escarpment showing older ages those located below. Thermal history inversion was performed using QTQt that enables a joint modelling of AHe, AFTA and fission track lengths. The data provide robust well-constrained evidence for a major period of cooling during the late Cretaceous (circa 90 Ma). From local measurement of the geothermal gradient and estimation of palaeo-thermal gradient we show that these data are best explained by an erosion event which could have led to removal of about 3.5 kilometers in the central part of the plateau. These estimates agree with the offshore sedimentary records on the eastern craton margin. We discuss the perspectives offered by joint analyses of thermochronological data and the utilization of surface erosion models based on CASCADE to provide new insight into south-African uplift and role of mantle dynamics.

Neutron activation analysis of uranium by means of electrochemical etching of tracks in lawsan detectors

International Nuclear Information System (INIS)

Kim Son Chun; Chuburkov, Yu.T.; Zvara, I.I.

1982-01-01

The method of neutron activation analysis of uranium in natural and artificial materials using track lavsan detectors of fission fragments has been developed. The method of electrochemical etching (etching reagent NaOH) of fragment tracks in lavsan is improved. Using statistical method of experiment planning the equation, describing the dependence of diometer value of fission fragment tracks on parameters of etching process, is obtained. The analysis sensitivity is 10 - 7 g/g - 10 - 8 g/g

Fusion barrier distributions and fission anisotropies

International Nuclear Information System (INIS)

Hinde, D.J.; Morton, C.R.; Dasgupta, M.; Leigh, J.R.; Lestone, J.P.; Lemmon, R.C.; Mein, J.C.; Newton, J.O.; Timmers, H.; Rowley, N.; Kruppa, A.T.

1995-01-01

Fusion excitation functions for 16,17 O+ 144 Sm have been measured to high precision. The extracted fusion barrier distributions show a double-peaked structure interpreted in terms of coupling to inelastic collective excitations of the target. The effect of the positive Q-value neutron stripping channel is evident in the reaction with 17 O. Fission and evaporation residue cross-sections and excitation functions have been measured for the reaction of 16 O+ 208 Pb and the fusion barrier distribution and fission anisotropies determined. It is found that the moments of the fusion l-distribution determined from the fusion and fission measurements are in good agreement. ((orig.))

Temporal constraints on the tectonic evolution of Sierra De Famatina, northwestern Argentina, using the fission-track method to date tuffs interbedded in synorogenic clastic sedimentary strata

Energy Technology Data Exchange (ETDEWEB)

Tabbutt, K.D. (Dartmouth College, Hanover, NH (USA))

1990-07-01

Fission-track dates from seven volcaniclastic units allow time constraints to be placed on synorogenic clastic strata exposed along the flanks of Sierra de Famatina, northwest Argentina. Four formations are exposed along the western margin of Sierra de Famatina. The El Abra conglomerate is composed of clasts eroded from the basement exposed just to the west of Cadena de Paiman. The El Buey Formation contains sediments probably derived from the Precordillera fold and thrust belt to the west. Fission-track dates give a maximum age of 6 Ma for the deposition of both of these formations. The El Durazno Formation, deposited between 6 and 4 Ma, contains proximal volcaniclastic and other clastic rocks derived from the core of Sierra de Famatina. The Santa Florentina conglomerate was derived from the rising Sierra de Famatina and deposited in the past 4 m.y. Sierra de Famatima probably became a positive topographic feature approximately 6 Ma. Prior to that time this region was receiving fine-grained sediments from a distal fold and thrust belt and conglomerates from local basement uplifts. Minor extrusive events (Mogote Formation) coincide both spatially and temporally with deformation along the major reverse faults that control the uplift of Sierra de Famatina. Minimum mean uplift rates calculated for Sierra de Famatina are 0.8 {plus minus} 0.1 mm/yr over a 6.8 m.y. interval.

Use of 236Pu and 242Pu as a radiochemical tracer for estimation of Pu in bioassay samples by fission track analysis

International Nuclear Information System (INIS)

Sawant, Pramilla D.; Prabhu, Supreetha P.; Kalsi, P.C.

2008-01-01

236 Pu and 242 Pu are routinely used as radiochemical yield monitors in India for bioassay monitoring of occupational workers by alpha spectrometry. Fission Track Analysis (FTA) is also being standardized for trace level determination of Pu in bioassay samples. The present study, reports the utility of 236 Pu and 242 Pu as radiochemical tracers in estimation of Pu in bioassay samples by FTA technique. The advantages of using 236 Pu tracer in FTA over 242 Pu as well as the interference caused due to presence of 241 Pu in the bioassay samples of occupational workers handling power reactor grade Pu is discussed. (author)

Cross section of ternary fission of Al, Ti, Co and Zr nuclei induced by 0,8 - 1,8 Gev photons

International Nuclear Information System (INIS)

Lima, D.A. de; Sousa, E.V. de; Milomen, W.C.C.; Tavares, O.A.P.

1988-01-01

A research on ternary fission of Al, Ti, Co, and Zr nuclei induced by bremsstrahlung photons of 0,8, 1,0, 1,4, and 1,8 Gev end-point energies has been carried out using makrofol polycarbonate and CR-39 polymer as fission-track detectors. Results are discussed and compared with other ternary fission data. (M.W.O.) [pt

$\\bar{p}$-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 ...

Fast-track Orthognathic Surgery: An Evidence-based Review

Science.gov (United States)

Otero, Joel Joshi; Detriche, Olivier; Mommaerts, Maurice Yves

2017-01-01

The aim of this study was to establish a fast-track protocol for bimaxillary orthognathic surgery (OGS). Fast-track surgery (FTS) is a multidisciplinary approach where the pre-, intra-, and postoperative management is focusing maximally on a quick patient recovery and early discharge. To enable this, the patients’ presurgical stress and postsurgical discomfort should be maximally reduced. Both referral patterns and expenses within the health-care system are positively influenced by FTS. University hospital-literature review through Medline, Embase, and the Cochrane Library (January 2000–July 2016) using the following words – “fast track, enhanced recovery, multimodal, and perioperative care” – to define a protocol evidence based for OGS, as well as evidenced-based medicine search of every term added to the protocol during the same period. The process has resulted in an OGS protocol that may improve the outcome of the patient through several nonoperative and operative measures such as preoperative patient education and intra/postoperative measures that should improve overall patient satisfaction, decrease morbidity such as postoperative nausea, headache, dizziness, pain, and intubation discomfort, and shorten hospital stay. A literature review allowed us to fine-tune a fast-track protocol for uncomplicated OGS that can be prospectively studied against currently applied ones. PMID:29264281

Thermodynamics of nuclear track chemical etching

Science.gov (United States)

Rana, Mukhtar Ahmed

2018-05-01

This is a brief paper with new and useful scientific information on nuclear track chemical etching. Nuclear track etching is described here by using basic concepts of thermodynamics. Enthalpy, entropy and free energy parameters are considered for the nuclear track etching. The free energy of etching is determined using etching experiments of fission fragment tracks in CR-39. Relationship between the free energy and the etching temperature is explored and is found to be approximately linear. The above relationship is discussed. A simple enthalpy-entropy model of chemical etching is presented. Experimental and computational results presented here are of fundamental interest in nuclear track detection methodology.

Novel mitochondrial extensions provide evidence for a link between microtubule-directed movement and mitochondrial fission

International Nuclear Information System (INIS)

Bowes, Timothy; Gupta, Radhey S.

2008-01-01

Mitochondrial dynamics play an important role in a large number of cellular processes. Previously, we reported that treatment of mammalian cells with the cysteine-alkylators, N-ethylmaleimide and ethacrynic acid, induced rapid mitochondrial fusion forming a large reticulum approximately 30 min after treatment. Here, we further investigated this phenomenon using a number of techniques including live-cell confocal microscopy. In live cells, drug-induced fusion coincided with a cessation of fast mitochondrial movement which was dependent on microtubules. During this loss of movement, thin mitochondrial tubules extending from mitochondria were also observed, which we refer to as 'mitochondrial extensions'. The formation of these mitochondrial extensions, which were not observed in untreated cells, depended on microtubules and was abolished by pretreatment with nocodazole. In this study, we provide evidence that these extensions result from of a block in mitochondrial fission combined with continued application of motile force by microtubule-dependent motor complexes. Our observations strongly suggest the existence of a link between microtubule-based mitochondrial trafficking and mitochondrial fission

Fission 2009 4. International Workshop on Nuclear Fission and Fission Product Spectroscopy - Compilation of slides

International Nuclear Information System (INIS)

2009-01-01

This conference is dedicated to the last achievements in experimental and theoretical aspects of the nuclear fission process. The topics include: mass, charge and energy distribution, dynamical aspect of the fission process, nuclear data evaluation, quasi-fission and fission lifetime in super heavy elements, fission fragment spectroscopy, cross-section and fission barrier, and neutron and gamma emission. This document gathers the program of the conference and the slides of the presentations

Geochronologic (K-Ar/Fission track) east-west profile of the Rio Grande do Sul shield

International Nuclear Information System (INIS)

Poupeau, G.; Baitelli, R.; Berbert, M.

1985-01-01

An E-W sampling was executed from Pelotas to Dom Pedrito, Rio Grande do Sul state, for K-Ar and Fission-track (FT) dating. Within the Dom Feliciano Orogenic Belt, from pelotas to Pinheiro Machado, K-Ar in biotites increase from 530m.y. to 655 m.y., with a discontinuity at the level of the approx.10Km wide Cangacu cataclastic Zone. In two samples from the Rio de La Plata Craton, at the western end of our profile, hornblendes present K-Ar ages of 1.555m.y. and 1.594m.y. FT ages in apatites record cooling of these minerals below 120 + - 20 0 C. From Pelotas to Pinheiro Machado, four sample present concordant ages at 270 + - 10m.y., whiel western most sample records a later event at 216 m.y. From the structure of plateau-ages it is suggested that the events dated are two positive tectonic pulses. Examination of the sedimentary of the Parana Basin confirms this interpretation. We therefore dated isotopically, for the firts time in Rio Grande do Sul basement, the ages of the two tectonic pulses wich affected the sedimentation in the Parana Basin. (Author) [pt

Geochronologic (K-Ar/Fission Track) east-west profile of the Rio Grande do Sul shield

International Nuclear Information System (INIS)

Poupeau, G.; Baitelli, R.; Berbert, M.; Kawashita, K.

1985-01-01

An E-W sampling was executed from Pelotas to Dom Pedrito, Rio Grande do Sul State, for K-Ar and fission-track (FT) dating. Within the Dom Feliciano Orogenic Belt, from Pelotas to Pinheiro Machado, K-Ar in biotites increase from 530 m.y. to 655 m.y., with a discontinuity at the level of the 10 km wide Cangacu cataclastic Zone. In two samples from the Rio de La Plata Craton, at the Western end of our profile, hornblendes present K-Ar ages of 1.555 m.y and 1.594 m.y. FT ages in apatites record the cooling of these minerals below 120+- 20 0 C. From Pelotas to Pinheiro Machado, four samples present concordant ages at 270+ -10 m.y., while the western sample records a later event at 216 m.y. From the structure of plateau-ages it is suggested that the events dated are two positive tectonic pulses. Examination of the sedimentary of the Parana Basin confirms this interpretation. We therefore dated isotopically, for the first time in Rio Grande do Sul basement, the ages of the two tectonic pulses which affected the sedimentation in the Parana Basin. (Author) [pt

Assessment of plutonium exposures in Rongelap and Utirik populations by fission track analysis of urine

International Nuclear Information System (INIS)

Sun, L.C.; Moorthy, A.R.; Kaplan, E.; Baum, J.W.; Meinhold, C.B.

1994-01-01

A nuclear device, code-named Bravo, detonated at Bikini Atoll at 6:45 a.m. on 1 March 1954, unexpectedly released a large amount of radioactivity. Over 40 years after this incident, the study of its impact on the radiological health and environmental safety of the residents of Rongelap and Utirik Atolls continues. In 1987, researchers at Brookhaven National Laboratory established a fission track analysis (FTA) method for low-level 239 Pu urinalysis. Two years later, a new shipboard protocol was developed for collecting 24-h radiologically clean urine samples. The purpose of this paper is to update information on the FTA method for measuring low-levels of plutonium, and to summarize results on the distribution of 239 Pu in the populations of Rongelap and Utirik between 1981--1991. Plutonium detection levels (99% confidence level) in these samples were 2--3 μBq, which is equivalent to 0.2--0.3 mSv effective dose equivalent (EDE) to age 70 for Marshallese. The latest 1991 FTA data indicate average EDE of 0.62 mSv and 1.6 mSv for the people of Rongelap and Utirik, respectively, which both are the highest values since 1988

Assessment of plutonium exposures in Rongelap and Utirik populations by fission track analysis of urine

International Nuclear Information System (INIS)

Sun, L.C.; Moorthy, A.R.; Kaplan, E.; Baum, J.W.; Meinhold, C.B.

1995-01-01

A nuclear device, code-named Bravo, detonated at Bikini Atoll at 6.45 a.m. on 1 March 1954, unexpectedly released a large amount of radioactivity. Over 40 years after this incident, the study of its impact on the radiological health and environmental safety of the residents of Rongelap and Utirik Atolls continues. In 1987, researchers at Brookhaven National Laboratory established a fission track analysis (FTA) method for low-level 239 Pu urinalysis. Two years later, a new shipboard protocol was developed for collecting 24-h radiologically clean urine samples. The purpose of this paper is to update information on the FTA method for measuring low-levels of plutonium, and to summarize results on the distribution of 239 Pu in the populations of Rongelap and Utirik between 1981-1991. Plutonium detection levels (99% confidence level) in these samples were 2-3 μBq, which is equivalent to 0.2-0.3 mSv effective dose equivalent (EDE) to age 70 for Marshallese. The latest 1991 FTA data indicate average EDE of 0.62 mSv and 1.6 mSv for the people of Rongelap and Utirik, respectively, which both are the highest values since 1988. (author)

Nuclear fission and neutron-induced fission cross-sections

Energy Technology Data Exchange (ETDEWEB)

James, G.D.; Lynn, J.E.; Michaudon, A.; Rowlands, J.; de Saussure, G.

1981-01-01

A general presentation of current knowledge of the fission process is given with emphasis on the low energy fission of actinide nuclei and neutron induced fission. The need for and the required accuracy of fission cross section data in nuclear energy programs are discussed. A summary is given of the steps involved in fission cross section measurement and the range of available techniques. Methods of fission detection are described with emphasis on energy dependent changed and detector efficiency. Examples of cross section measurements are given and data reduction is discussed. The calculation of fission cross sections is discussed and relevant nuclear theory including the formation and decay of compound nuclei and energy level density is introduced. A description of a practical computation of fission cross sections is given.

Comparison of fission probabilities with emission of long range particles under the action of slow and fast neutrons on various materials; Probabilites comparees de fission avec emission de particules de long parcours pour divers materiaux sous l'action des neutrons lents et rapides

Energy Technology Data Exchange (ETDEWEB)

Netter, F; Faraggi, H; Garin-Bonnet, A; Julien, J; Corge, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Turkiewicz, J [Institut de Recherches Nucleaire de Varsovie (Poland)

1958-07-01

The authors describe relative cross-section measurements of fission of the isotopes of uranium and plutonium (more particularly {sup 235}U, {sup 238}U, {sup 239}Pu), with emission of long range particles, under the action of neutrons of various energies: thermal neutrons, pile neutrons, neutrons produced with the Van de Graaff accelerator by reaction of protons on tritium. The measurements are carried out: 1) with the aid of photographic plates, by submitting to the action of the neutrons a layer of fissile material coupled with an Ilford nuclear emulsion of 200 microns; a tin sheet laying between the plate and the layer stops the {alpha} particles and the fission fragments. By an appropriate development the tracks of the long range particles can be distinguished in the emulsion, from the tracks of the recoil protons resulting of fission neutrons, or of the last primary neutrons. For neutrons of energy under 1 MeV, the compared frequency of the tracks of long range particles and of the recoils caused by the fission neutrons gives a measurement of the fission cross-section with emission of long range particles relative to the product of the fission cross-section by the mean number of neutrons emitted by fission. For neutrons of higher energy, one measures only the frequency of the tracks of long range particles, comparatively with the flux of primary neutrons. Some precautions are taken to eliminate the action of thermal neutrons in the measurements with fast neutrons. 2) with the aid of a system of ionization chamber and proportional counter, the rate of coincidence between the impulsions caused by the long range particles and the impulsions provided by one of the fission fragments is measured comparatively with the counting rate of fission fragme (author) [French] Les auteurs decrivent des mesures relatives a la section efficace de fission des isotopes de l'uranium et du plutonium (notamment {sup 235}U, {sup 238}U, {sup 239}Pu) avec emission de particules de long

Thermochronology of the South American platform in the state of Sao Paulo, Brazil, through apatite fission tracks

International Nuclear Information System (INIS)

Tello Saenz, C.A.; Hadler Neto, J.C.; Iunes, P.J.; Guedes, S.; Hackspacher, P.C.; Ribeiro, L.F.B.; Paulo, S.R.; Osorio A, A.M.

2005-01-01

The fission-track method (FTM) in apatite was applied to 45 samples collected in the Serra da Mantiqueira (Mantiqueira mountain range), the Serra do Mar (Mar mountain range), regions next to these mountain ranges and the coastal region between Ubatuba and Santos in the State of Sao Paulo, Brazil, to study the thermochronology of the South American Platform in southeast Brazil and its influence on Santos and Campos basins. The data presented in this work complement the previously presented data on the same region (Tello Saenz et al., 2003. J. S. Am. Earth Sci. 15, 765-774) with 31 new samples analyzed. The weighted mean of the corrected ages from high Mantiqueira (around 1000m), (121+/-6)Ma, coincides with the South Atlantic opening. The fact that its thermal history starts at a relatively low temperature (∼80 deg. C) suggests that the age of ∼120Ma would be the formation age of Serra da Mantiqueira due to a rapid pulse, in which tracks had no time to be retained at the closure temperature, that is ∼120 deg. C. The Serra do Mar presents a more complicated thermal history, with several reactivations indicated by the changes in the slope of its cooling curve. The thermal histories obtained in the regions next to these mountain ranges are compatible with the results mentioned above. The Santos Basin has unconformities that agree with changes in the slope thermal histories of the studied region

Nuclear fission and fission-product spectroscopy: 3. International workshop on nuclear fission and fission-product spectroscopy

International Nuclear Information System (INIS)

Goutte, Heloise; Fioni, Gabriele; Faust, Herbert; Goutte, Dominique

2005-01-01

The present book contains the proceedings of the third workshop in a series of workshops previously held in Seyssins in 1994 and 1998. The meeting was jointly organized by different divisions of CEA and two major international laboratories. In the opening address, Prof. B. Bigot, the French High Commissioner for Atomic Energy, outlined France's energy policy for the next few decades. He emphasized the continuing progress of nuclear fission in both technical and economic terms, allowing it to contribute to the energy needs of the planet even more in the future than it does today. Such progress implies a very strong link between fundamental and applied research based on experimental and theoretical approaches. The workshop gathered the different nuclear communities studying the fission process, including topics as the following: - nuclear fission experiments, - spectroscopy of neutron rich nuclei, - fission data evaluation, - theoretical aspects of nuclear fission, - and innovative nuclear systems and new facilities. The scientific program was suggested by an International Advisory Committee. About 100 scientists from 13 different countries attended the conference in the friendly working atmosphere of the Castle of Cadarache in the heart of the Provence. The proceedings of the workshop were divided into 11 sections addressing the following subject matters: 1. Cross sections and resonances (5 papers); 2. Fission at higher energies - I (5 papers); 3. Fission: mass and charge yields (4 papers); 4. Light particles and cluster emission (4 papers); 5. Spectroscopy of neutron rich nuclei (5 papers); 6. Resonances, barriers, and fission times (5 papers); 7. Fragment excitation and neutron emission (4 papers); 8. Mass and energy distributions (4 papers); 9. Needs for nuclear data and new facilities - I (4 papers); 10. Angular momenta and fission at higher Energies - II (3 papers); 11. New facilities - II (2 papers). A poster session of 8 presentations completed the workshop

Fission of Al, Ti, Co, Zr, Nb, Ag, In, Nd, Sm, and Ta nuclei induced by 0.8-1.8 GeV photons

International Nuclear Information System (INIS)

Lima, D.A. de; Martins, J.B.; Tavares, O.A.P.

1989-01-01

Samples of Al, Ti, Co, Zr, Nb, Ag, In, Nd, Sm, and Ta elements in contact with solid state nuclear track detectors were exposed to 0.8-1.8 GeV bremsstrahlung beams at the 2.5-GeV Electron Synchrotron of the Bonn University. The detectors were processed to produce visible fission tracks for track analysis with optical microscopes. Absolute mean cross section per photon and fissility were evaluated. Results are discussed and compared with other photofission data as well as with estimates from the current fission models. A broad minimum found for nuclear fissility of 10 -4 -10 -3 covering the range 15 approx Z 2 /A approx 25 seems to confirm the predictions from the models. For Al and Ti nuclei the probability of fission amounts to approx 10 -1 . (author) [pt

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)

Low-energy nuclear fission and our understanding of the nucleus

International Nuclear Information System (INIS)

Hall, H.L.; Hoffman, D.C.

1990-01-01

The interactions between experimental discoveries in low-energy nuclear fission and the theoretical understanding of the structure of the nucleus are reviewed. The history of this synergistic relationship begins with the discovery of fission, the development of the liquid-drop model and the experimental evidence for magic numbers, continues through the development of the shell model, the experimental discovery of shape isomerism, the double-humped fission barrier the spontaneous fission half-life disaster, the discovery of symmetric mass division in spontaneous fission and theoretical treatments based on different paths to scission. It concludes with a brief review of current experimental and theoretical understanding of low-energy fission and the prospects for future developments. (author) 150 refs.; 5 figs.; 1 tab

Use of combined alpha-spectrometry and fission track analysis for the determination of 240Pu/239Pu ratios in human tissue

International Nuclear Information System (INIS)

Love, S.F.; Filby, R.H.; Glover, S.E.; Stuit, D.B.; Kathren, R.L.

1998-01-01

Plutonium and other actinides were determined in human autopsy tissues of occupationally exposed workers who were registrants of the United States Transuranium and Uranium Registries (USTUR). In this study, Pu was purified and isolated from Am, U and Th, after drying and wet-ashing of the tissues, and the addition of 238 Pu as a radiotracer. After electrodeposition onto vanadium planchets, the 239+240 Pu activity was determined by alpha-spectrometry. A fission track method was developed to determine 239 Pu in the presence of 238 Pu and 240 Pu, using Lexan TM polycarbonate detectors. Combining the two techniques allowed the determination of the 240 Pu/ 239 Pu activity and atom ratios. Data from selected USTUR cases are presented. (author)

Fission track and petrostructural analysis of carbonatic massif of Tamazert ( high central Atlas, Morocco) and neogene reactivation of the north-atlasic fault

International Nuclear Information System (INIS)

Ziad, N.; Khazrouni, S.; Tayebi, M.; Bouabdli, A.; Poupeau, G.

2001-01-01

The uranium fission-track dating method is used in geochronological survey of basic apatites extracted from the Tamazert complex. The result of this survey coupled with those of petrostructural analysis of this massif enabled as to distinguish three age groups: 32.4 Myr, 23.3 Myr and 12.6 Myr. The first age corresponds to the setting up of the massif, whereas the two other ages indicate later emissions. The setting up of the sill whose age is 12.6 Myr induced a partial rejuvenation of the emission age og the massif. This late volcanic emission is probably related to the north-atlasic fault activity. 4 figs., 1 tab., 30 refs. (au)

Cretaceous to present paleothermal gradients, central Negev, Israel: constraints from fission track dating

International Nuclear Information System (INIS)

Kohn, B.P.; Feinstein, S.; Eyal, M.

1990-01-01

Apatite and zircon fission track ages (FTA), vitrinite reflectance (VR) data and burial history curves were integrated for reconstruction of Early Cretaceous to present maximum thermal gradients in four deep boreholes in the central Negev, Isreal. The most complete data set is available from the Ramon 1 borehole. Supplementary data were obtained from Hameishar 1, Makhtesh Qatan 2, and Kurnub 1 boreholes. Between ca. 122-90 Ma the constraints on thermal gradient obtained from apatite FTA overlap with those derived from zircon FT and VR data, restricting them to 0 C km -l . Apatite FTA between 90 and 80 Ma in Ramon 1 and Hameishar 1 suggest rapid cooling at the time recorded or earlier. Constraints on thermal gradient history derived from these ages are considerably strengthened over a short time span. From 80 Ma to the present, FTA data indicate that gradients had probably decayed to present-day regional levels (ca. 20 0 C km -1 ) by Early Tertiary time. Thermal constraints derived from apatite FTA and VR data in Makhtesh Qatan 2 and Kurnub 1 boreholes are consistent with those obtained post-56 Ma for Ramon 1. For pre-56 Ma, only VR data are available and these indicate considerably lower maximum gradients than those obtained for the same time period from Ramon 1. This dichotomy reflects different Early Cretaceous-Early Tertiary thermal regimes between the northern and southern parts of the study area. (author)

Dynamics in heavy ion fusion and fission

International Nuclear Information System (INIS)

Bjoernholm, S.

1972-01-01

Dynamical aspects of heavy ion fussion and fission, mainly the aspect of damping which is meant as the dissipation of kinetic energy and the aspect of the effective mass of the fission motion, are discussed. Two categories of evidence of damping effects are given. One relates to the damping of the fission motion for the ground state shape and for the isomeric more elongated shape. The other relates to the damping of the fission motion from the last barrier to the scission point. The dependence of the effective mass associated with the fission motion on the deormation of nucleus is shown. As the elongation of the nucleus increases the effective mass of the fission motion varies strongly from being about forty times greater than the reduced mass in the beta-vibrational state of the ground state shape to being equal to the reduced mass in the moment of scission. Damping effects are expected to be propartional to the difference between the effective mass and the reduced mass. It is concluded that the damping in fussion reactions is relatively weak for lighter products and quite strong for superheavy products like 236 U or 252 Cf. (S.B.)

Detection of fission fragments and alpha particles using the solid trace detector CR-39

International Nuclear Information System (INIS)

Santos, R.C.

1988-01-01

The technique of detecting charged particles using the solid track detector CR-39 is employed to establish some characteristics of fission fragments and alpha particles emitted from a Cf-252 source. Results are presented and discussed on the following aspects i) distribution of the track diameters; ii) variations on the track diameters to the chemical attack; iii) variations of the chemical attack velocity with respect to concentration and temperature. iv) activation energy of the developping process; v) induction time; vi) critical angle and efficiency on track developping. (A.C.A.S.) [pt

Simulating fission product transients via the history-based local-parameter methodology

International Nuclear Information System (INIS)

Jenkins, D.A.; Rouben, B.; Salvatore, M.

1993-01-01

This paper describes the fission-product-calculation capacity of the history-based local-parameter methodology for evaluating lattice properties for use in core-tracking calculations in CANDU reactors. In addition to taking into account the individual past history of each bundles flux/power level, fuel temperature, and coolant density and temperature that the bundle has seen during its stay in the core, the latest refinement of the history-based method provides the capability of fission-product-drivers. It allows the bundle-specific concentrations of the three basic groups of saturating fission products to be calculated in steady state or following a power transient, including long shutdowns. The new capability is illustrated by simulating the startup period following a typical long-shutdown, starting from a snapshot in the Point Lepreau operating history. 9 refs., 7 tabs

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)

Fission track analysis method of urine plutonium and estimation of plutonium-239 internal dose to Marshallese

International Nuclear Information System (INIS)

Zhao Shixuan

1995-01-01

Bravo detonated at Bikini Atoll on the morning of March 1, 1954, unexpectedly released a large amount of radioactive fallout on the areas. Impact studies on the radiological health and safety of the residents living in the contaminated environments are still undergoing. For plutonium dose assessment, researchers at Brookhaven National Laboratory established a fission track analysis (FTA) method for low-level 239 Pu measurement. Furthermore, a new shipboard protocol was developed for collecting 24-h radiologically clean urine samples. The purposes of this paper are to update information on the FTA processes and to present a set of results on the 239 Pu measurements in the Marshallese populations (Rongelap and Utirik) between 1981-1991. The detection sensitivity of FTA method (99% confidence level) in these samples was 2-3 μBq which is equivalent to 0.2-0.3 mSv effective dose equivalent (EDE) to age 70 for the Marshallese. The latest 1991 FTA data indicate average EDE of 0.62 mSv and 1.6 mSv for the people of Rongelap and Utirik, respectively, which both are the highest values since 1988

Device for glass detector tracks processing

International Nuclear Information System (INIS)

Zhukov, A.V.; Mikheev, V.P.; Pis'mennyj, G.V.; Pribytov, V.I.; Rozov, B.S.

1974-01-01

The authors describe a semi-automatic installation for measuring angular distribution of tracks from nuclear fission fragments. The measurements were performed on glass detectors represented by a cylinder surface section with central angle 110-120 deg, height 20 mm and radius 45 mm. The tracks were in the form of lunes, 10/25 mm deep. Treatment of one detector lasted 10-15 min. The installation affords the possibility of finding the angular distribution of tracks by counting them in zones, whose sizes may vary from 1 to 90 deg. Data output was performed on a digitizer [ru

Evidence-based surgical care and the evolution of fast-track surgery

DEFF Research Database (Denmark)

Kehlet, H.; Wilmore, D.W.

2008-01-01

, randomized studies, and meta-analyses, the concept of the "fast-track methodology" has uniformly provided a major enhancement in recovery leading to decreased hospital stay and with an apparent reduction in medical morbidity but unaltered "surgery-specific" morbidity in a variety of procedures. However......BACKGROUND: Optimization of postoperative outcome requires the application of evidence-based principles of care carefully integrated into a multimodal rehabilitation program. OBJECTIVE: To assess, synthesize, and discuss implementation of "fast-track" recovery programs. DATA SOURCES: Medline MBASE...... (January 1966-May 2007) and the Cochrane library (January 1966-May 2007) were searched using the following keywords: fast-track, enhanced recovery, accelerated rehabilitation, and multimodal and perioperative care. In addition, the synthesis on the many specific interventions and organizational...

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.

Growth of fine holes in polyethyleneterephthalate film irradiated by fission fragments

International Nuclear Information System (INIS)

Komaki, Y.; Tsujimura, S.

1975-01-01

Growth of fine holes by chemical etching in polyethyleneterephthalate films exposed to fission fragments were followed by measuring gas flow through films. The etching rate along tracks and the radial etching rate were determined at hole diameters of 100--3000 A and hole densities of 10 6 --10 8 /cm 2

Fission track analysis and evolution of mesozoic-paleozoic hydrocarbon resource-rocks headed in Northern Jiangsu-South Yellow sea basin

International Nuclear Information System (INIS)

Xu Hong; Cai Qianzhong; Sun Heqing; Guo Zhenxuan; Yan Guijing; Dai Jing; Liu Dongying

2008-01-01

Fission track data of different geologic epoches from Binhai salient, Yancheng sag, Haian sag, Baiju sag, Gaoyou sag, Hongze sag and Jinhu sag of northern Jiangsu basin and seismic data from Laoshan uplift in South Yellow Sea basin and evolution of Paleozoic hydrocarbon resource-rocks headed in the Northern Jiangsu-South Yellow Sea basin were studied. Results indicate that Binhai salient uplifted in 38-15 Ma, forming 'structure uplifting model', Paleozoic hydrocarbon resource-rocks have the appearance of 'different layers but identical mature, different layers but identical temperature' with Laoshan uplift. All sags have the characters of 'long time heating model', and sedimentations in Cenozoic were exploited by 2 km. Mesozoic-Paleozoic hydrocarbon resource- rocks of Laoshan uplift get ahead of 10 km. Structure evolution was compared with Binhai salient. According to the modeling results of secondary hydrocarbon generation, Mesozoic-Paleozoic hydrocarbon resource-rocks of Laoshan uplift have the good reservoir potentiality and probably become an important new window for sea oil and gas exploration. (authors)

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.

Effect of gamma-ray and electron irradiation on the response of solid-state track detectors

International Nuclear Information System (INIS)

Fukuda, Kyue

1980-01-01

Specimens of muscovite mica were first exposed to fission fragments and then to various gamma-ray fields from a 60 Co source ranging from 1.9 x 10 3 to 1.6 x 10 4 Mrad dose. The results show that the average etched width of fission-fragment tracks decreases with increasing gamma-ray dose. Shallow pits were observed in etched specimens when the gamma-ray dose exceeded 5 x 10 3 Mrad. Numerous shallow etch pits caused by the gamma-ray irradiation interfered with the observation of fission tracks in the specimens. No shallow etch pits were observed in the specimen annealed for 100 min at 600 0 C before the gamma-ray irradiation. Pre-annealing extends the ''safety limits'' of gamma background below which muscovite mica can be used to observe fission tracks without any gamma-ray interference. Gamma-ray and electron irradiation caused significant increase of the resistance to thermal decomposition of muscovite mica. The resistance increased markedly in the dose range from 5 x 10 3 to 8 x 10 3 Mrad. These phenomena suggest the use of mica to assess radiation doses of gamma rays and electrons up to several thousand megarads. (author)

Mapping of uranium and thorium in radioactive rocks using nuclear track solid detectors

International Nuclear Information System (INIS)

Bouch, C.M.

1982-01-01

α-Autoradiography and studies of induced fission in a research nuclear reactor (IEA-R1, IPEN, Sao Paulo) were done, employing Solid-State Nuclear Track detectors, in order to study the distribution of α-emitters, U and Th in rocks. Polished sections of rocks were prepared and photographed. Etching conditions were studied in order to adapt the detectors to the studies of microdistribution and macrodistribution of tracks. Polycarbonate foils (Bayer, Makrofol) were chosen as fission-fragments detectors and the technique of fission induced with reactor neutrons to obtain the distribution of U and Th were studied. Uranium and thorium standards evaporated on the surface of the detectors, as well as thorite and uraninite grains, were irradiated in order to measure the integrated flux of neutrons, the effective cross sections for fission with reactor neutrons for 232 Th(0,05b) and 238 U(0,30b) and to study the contribution of 238 U fission in thorium mapping. A technique for determination of uranium and thorium in minerals was studied and applied to Mica, for which were determined the contents of 4,2 ppb U e 58 ppb Th. (Author) [pt

60 years controlled nuclear fission: CP-1

International Nuclear Information System (INIS)

Anon.

2002-01-01

On December 2, 1942, the Chicago Pile 1 (CP-1) went critical for the first time. In this way, the scientists and engineers involved in the project under the leadership of Enrico Fermi succeeded in demonstrating that a self-sustaining nuclear reaction with nuclear fission processes was technically feasible. Only four years after the discovery and proof of nuclear fission by Otto Hahn, Fritz Strassmann, and Lise Meitner, the experiment consisting of graphite blocks as the moderator and uranium dioxide pellets as the fuel, as well as instrumentation and control devices, had been set up in the former squash court of the field and track stadium of the University of Chicago. Precisely at 3.36 a.m. Chicago time, after control rods had been withdrawn, the instruments showed the chain reaction by the neutron flux they indicated. An important cornerstone in the use of nuclear power had thus been laid. (orig.)

[Fission product yields of 60 fissioning reactions]. Final report

International Nuclear Information System (INIS)

Rider, B.F.

1995-01-01

In keeping with the statement of work, I have examined the fission product yields of 60 fissioning reactions. In co-authorship with the UTR (University Technical Representative) Talmadge R. England ''Evaluation and Compilation of Fission Product Yields 1993,'' LA-UR-94-3106(ENDF-349) October, (1994) was published. This is an evaluated set of fission product Yields for use in calculation of decay heat curves with improved accuracy has been prepared. These evaluated yields are based on all known experimental data through 1992. Unmeasured fission product yields are calculated from charge distribution, pairing effects, and isomeric state models developed at Los Alamos National Laboratory. The current evaluation has been distributed as the ENDF/B-VI fission product yield data set

Some aspects of the nuclear fission process; Quelques aspects du processus de fission nucleaire

Energy Technology Data Exchange (ETDEWEB)

Netter, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-07-01

In the following report one can find first a short general view on the present situation of our knowledge concerning the nuclear fission process, namely on the nucleus going through the saddle-point. Then there are some aspects connected with the excitation energy of the fissioning nucleus. The measurements made at Saclay on the fast neutron fission cross-section of U{sup 233}, U{sup 235}, Pu{sup 239}, U{sup 238} are described at the beginning of this work. It appears that for U{sup 233} there is some characteristic shape modulation of the cross-section curve, in relation with the collective excited state of the deformed nucleus at the saddle-point. Good evidence of this is also given by the study of the relative fission rate with emission of long-range particles; it appears also that this ternary fission rate does not change substantially for neutron between thermal energy and 2 MeV, but that is very lower for the compound nucleus U{sup 239} than for even-even compound nuclei. At the end there are some experiments on the strong 4,5 MeV gamma-ray originated by slow neutron absorption in U{sup 235}. Time-of-flight device is used to establish that this 4,5 MeV gamma-ray seems mostly connected with radiative capture. (author) [French] Le present travail debute par un apercu de l'etat actuel de nos connaissances sur le processus de fission nucleaire, notamment sur le passage par le point-seuil. Puis sont evoques des aspects lies au niveau d'energie d'excitation auquel est porte le noyau qui subit la fission. Les mesures de sections efficaces de fission induite dans {sup 233}U, {sup 235}U, {sup 239}Pu et {sup 238}U par des neutrons rapides effectuees a Saclay sont decrites en premier lieu; elles font apparaitre pour {sup 233}U une ondulation caracteristique du role des etats collectifs d'excitation du noyau deforme au point-seuil. Des experiences sur la fission avec emission de particules de long parcours confirment cet aspect tout en demontrant que la frequence

Influence of the particle discriminator for producing the microporous nuclear track etched membrane

International Nuclear Information System (INIS)

Thongphud, Apaporn; Ratanatongchai, Wichian; Supaphol, Pitt; Visal-athaphand, Pinpan

2005-10-01

The particle discriminator was used to focus the fission fragments from nuclear fission reaction between thermal neutron from the Thai Research Reactor and U-235 in uranium screen to strike almost normally to the polycarbonate (PC) film. The latent tracks in the thin 15 mm PC film were revealed after etching in 6N NaOH solution at 70 o C for 60 min. It was found that the tracks were porous. The porosity was more discrete and the pore shape was more circular as well. The track diameter was measured 3.73 +- 0.32 mm. It was also found that using particle discriminators with increasing thickness during exposure gives fewer pores in the PC film, after chemical etching under the same condition as above

Thermal history of the Krishna-Godavari basin, India: Constraints from apatite fission track thermochronology and organic maturity data

Science.gov (United States)

Sahu, Himansu S.; Raab, Matthias J.; Kohn, Barry P.; Gleadow, Andrew J. W.; Bal, Kiron D.

2013-09-01

The Krishna-Godavari (KG) basin, a passive margin Late Carboniferous to Holocene basin along the rifted east coast of India, includes the deltaic and inter-deltaic regions of the Krishna and Godavari rivers onshore and extends into the offshore. It is one of India's premier hydrocarbon-bearing basins. In an attempt to better understand the thermal history of the basin, apatite fission track (AFT) data has been obtained from six exploration wells (five onshore and one offshore). AFT thermal history models as well as other thermal indicators e.g. vitrinite reflectance (VR), Rock-Eval Tmax data reveal that the host rocks are currently at their maximum post-depositional temperatures and that any possible heating related to small-scale tectonism or rifting episodes in the basin bears little significance on the maturation of the sediments. In the case of one borehole (M-1) however, the organic maturity data reveals a period of Oligocene cooling across an unconformity when ∼1000 m of section was eroded due to falling sea-level. This information offers the potential for improved basin modeling of the KG basin.

Solid state track recorder measurements in the poolside critical assembly

International Nuclear Information System (INIS)

Ruddy, F.H.; Gold, R.; Roberts, J.H.

1979-01-01

Fission rate measurements using solid state track recorders (SSTR) have been performed at the PCA. A schematic representation of a cross-section of the PCA is shown. Fission rates were measured in the pressure vessel simulator at the T/4, T/2 and 3T/4 positions and in the void box (VB). SSTR measurements were carried out with 232 Th, 235 U (bare and cadmium covered), 238 U and 237 Np fissionable deposits. Midplane only measurements were carried out for 235 U and 237 Np, while 5 axial locations at 1/4T and 1/2T and 3 axial locations at 3/4T and in the VB were sampled for 232 Th and 238 U. The HEDL SSTR fission rate measurements reported herein for both configurations together with NBS and CEN/SCK fission chamber measurements will be used to establish absolute and relative fission reaction rates, and ratios for the PCA pressure vessel Benchmark Facility

Plutonium and surrogate fission products in a composite ceramic waste form

International Nuclear Information System (INIS)

Esh, D. W.; Frank, S. M.; Goff, K. M.; Johnson, S. G.; Moschetti, T. L.; O'Holleran, T.

1999-01-01

Argonne National Laboratory is developing a ceramic waste form to immobilize salt containing fission products and transuranic elements. Preliminary results have been presented for ceramic waste forms containing surrogate fission products such as cesium and the lanthanides. In this work results from scanning electron microscopy/energy dispersive spectroscopy and x-ray diffraction are presented in greater detail for ceramic waste forms containing surrogate fission products. Additionally, results for waste forms containing plutonium and surrogate fission products are presented. Most of the surrogate fission products appear to be silicates or aluminosilicates whereas the plutonium is usually found in an oxide form. There is also evidence for the presence of plutonium within the sodalite phase although the chemical speciation of the plutonium is not known

Ternary fission

International Nuclear Information System (INIS)

Wagemans, C.

1991-01-01

Since its discovery in 1946, light (charged) particle accompanied fission (ternary fission) has been extensively studied, for spontaneous as well as for induced fission reactions. The reason for this interest was twofold: the ternary particles being emitted in space and time close to the scission point were expected to supply information on the scission point configuration and the ternary fission process was an important source of helium, tritium, and hydrogen production in nuclear reactors, for which data were requested by the nuclear industry. Significant experimental progress has been realized with the advent of high-resolution detectors, powerful multiparameter data acquisition systems, and intense neutron and photon beams. As far as theory is concerned, the trajectory calculations (in which scission point parameters are deduced from the experimental observations) have been very much improved. An attempt was made to explain ternary particle emission in terms of a Plateau-Rayleigh hydrodynamical instability of a relatively long cylindrical neck or cylindrical nucleus. New results have also been obtained on the so-called open-quotes trueclose quotes ternary fission (fission in three about-equal fragments). The spontaneous emission of charged particles has also clearly been demonstrated in recent years. This chapter discusses the main characteristics of ternary fission, theoretical models, light particle emission probabilities, the dependence of the emission probabilities on experimental variables, light particle energy distributions, light particle angular distributions, correlations between light particle accompanied fission observables, open-quotes trueclose quotes ternary fission, and spontaneous emission of heavy ions. 143 refs., 18 figs., 8 tabs

Measurement of {sup 238}Np fission cross-section by neutrons near thermal point (preliminary results)

Energy Technology Data Exchange (ETDEWEB)

Abramo; vich, S.N.; Andreev, M.F.; Bol`shakov, Y.M. [Institute of Experimental Physics, Arzamas (Russian Federation)] [and others

1995-10-01

Measurements have been carried out of {sup 238}Np fission cross-section by thermal neutrons. The isotope {sup 238}Np was built up through the reaction {sup 238}U(p,n) on an electrostatic accelerator. Extraction and cleaning of the sample were done by ion-exchange chromatography. Fast neutrons were generated on the electrostatic accelerator through the reaction {sup 9}Be(d,n); a polyethylene block was used to slow down neutrons. Registration of fission fragments was performed with dielectric track detectors. Suggesting that the behavior of {sup 238}Np and {sup 238}U. Westscott`s factors are indentical the fission cross-section of {sup 238}Np was obtained: {sigma}{sub fo}=2110 {plus_minus} 75 barn.

Fission level densities

International Nuclear Information System (INIS)

Maslov, V.M.

1998-01-01

Fission level densities (or fissioning nucleus level densities at fission saddle deformations) are required for statistical model calculations of actinide fission cross sections. Back-shifted Fermi-Gas Model, Constant Temperature Model and Generalized Superfluid Model (GSM) are widely used for the description of level densities at stable deformations. These models provide approximately identical level density description at excitations close to the neutron binding energy. It is at low excitation energies that they are discrepant, while this energy region is crucial for fission cross section calculations. A drawback of back-shifted Fermi gas model and traditional constant temperature model approaches is that it is difficult to include in a consistent way pair correlations, collective effects and shell effects. Pair, shell and collective properties of nucleus do not reduce just to the renormalization of level density parameter a, but influence the energy dependence of level densities. These effects turn out to be important because they seem to depend upon deformation of either equilibrium or saddle-point. These effects are easily introduced within GSM approach. Fission barriers are another key ingredients involved in the fission cross section calculations. Fission level density and barrier parameters are strongly interdependent. This is the reason for including fission barrier parameters along with the fission level densities in the Starter File. The recommended file is maslov.dat - fission barrier parameters. Recent version of actinide fission barrier data obtained in Obninsk (obninsk.dat) should only be considered as a guide for selection of initial parameters. These data are included in the Starter File, together with the fission barrier parameters recommended by CNDC (beijing.dat), for completeness. (author)

Preliminary study of geotectonic evolution of the southern region of Sao Francisco (MG, Brazil) craton: an interpretation based on Rb-Sr, K-Ar, Pb-Pb and fission track data

International Nuclear Information System (INIS)

Teixeira, W.; Fonseca, A.C.; Poupeau, G.; Padilha, A.V.; Zapparolli, L.H.; Kawashita, K.; Khoury, M.C.

1985-01-01

The results obtained from isotopic dating techniques (Rb-Sr, K-Ar, Pb-Pb and fission tracks) applied to samples from the southern region of Sao Francisco craton (Mg, Brazil) are discussed. Rb-Sr and Pb-Pb ages, in total rock, allowed the determination of crust enlargement, with eventual modifications of the pre-existing crust, during the Late Archean period (3000 to 2600 million years) and the Inferior Proterozoic period (2400 to 2100 m.y.). Three main cooling periods of time were determined by K-Ar dating of mica, amphiboles and total rock at the craton border: 2200 to 1700 m.y., 1300 to 1100 m.y. and 900 to 400 m.y. related, respectively, to superposition of three cycles: Transamazonico, Uruacuano and Brasiliano. Cooling below 110 0 C, detected by the fission track method applied to apatites, pointed out an age of 850 m.y. at the internal parts and 550 m.y. at the craton periphery, thus showing a progressive action of Brazilian marginal movable zones in the studied region. The application of these two techniques together enabled the evaluation of the rocks cooling shape. Cooling of these samples was complex between 2700 and 2200 m.y. and slow from 2000 m.y. onwards. The integrated treatment of data from the various dating techniques is of great importance to know the geotectonic evolution of ancient polycyclic sites. (C.L.B.) [pt

Fission product behavior in the Molten Salt Reactor Experiment

International Nuclear Information System (INIS)

Compere, E.L.; Kirslis, S.S.; Bohlmann, E.G.; Blankenship, F.F.; Grimes, W.R.

1975-10-01

Essentially all the fission product data for numerous and varied samples taken during operation of the Molten Salt Reactor Experiment or as part of the examination of specimens removed after particular phases of operation are reported, together with the appropriate inventory or other basis of comparison, and relevant reactor parameters and conditions. Fission product behavior fell into distinct chemical groups. Evidence for fission product behavior during operation over a period of 26 months with 235 U fuel (more than 9000 effective full-power hours) was consistent with behavior during operation using 233 U fuel over a period of about 15 months (more than 5100 effective full-power hours)

Some aspects of the nuclear fission process

International Nuclear Information System (INIS)

Netter, F.

1961-01-01

In the following report one can find first a short general view on the present situation of our knowledge concerning the nuclear fission process, namely on the nucleus going through the saddle-point. Then there are some aspects connected with the excitation energy of the fissioning nucleus. The measurements made at Saclay on the fast neutron fission cross-section of U 233 , U 235 , Pu 239 , U 238 are described at the beginning of this work. It appears that for U 233 there is some characteristic shape modulation of the cross-section curve, in relation with the collective excited state of the deformed nucleus at the saddle-point. Good evidence of this is also given by the study of the relative fission rate with emission of long-range particles; it appears also that this ternary fission rate does not change substantially for neutron between thermal energy and 2 MeV, but that is very lower for the compound nucleus U 239 than for even-even compound nuclei. At the end there are some experiments on the strong 4,5 MeV gamma-ray originated by slow neutron absorption in U 235 . Time-of-flight device is used to establish that this 4,5 MeV gamma-ray seems mostly connected with radiative capture. (author) [fr

Nuclear fission - the great discovery of the nuclear chemistry 50 years ago

International Nuclear Information System (INIS)

Eichler, B.

1988-01-01

A scientific discovery only seldom in that extent has influenced the scientific-technical progress and the historical development of mankind as the discovery of nuclear fission. The investigation of the reactions at irradiation of the uranium with neutrons was historically the order of the day. In 1938, the radiochemical proof of the nuclear fission succeeded by coprecipitation, fractional crystallization and application of the tracer method. To be master of these methods as well as their profound physico-chemical insight enabled O. Hahn and F. Strassmann to give reliable evidence of fission by identifying the fission product barium. (author)

Yields of some fragments on 235U, 238U and 239Pu fission due to the neutrons of the SBR-1 reactors

International Nuclear Information System (INIS)

Yurova, L.N.; Bushuev, A.V.; Ozerkov, V.N.; Chachin, V.V.; Zvonarev, A.V.; Liforov, Yu.G.; Koleganov, Yu.V.; Miller, V.V.; Gorbatyuk, O.V.

1979-01-01

Determined are the values of the yields of fission fragments in spectrum close to that of the neutron fission using the data on yields at fission by thermal neutrons. The relation between the activities of fragments in samples irradiated in the BR-1 center and in the thermal colomn of the same reactor was measured with the help of the Ge(Li). The relative rate of fissions in uranium and plutonium samples in the center or in thermal colomn were measured by track detectors. The comparison of the yields obtained and the data of other authors is being made

Characterization of the fusion-fission process in light nuclear systems

International Nuclear Information System (INIS)

Anjos, R.M. dos.

1992-01-01

Fusion cross sections measurements of highly damped processes and elastic scattering were performed for the 16, 17, 18 O + 10, 11 B and 19 F + 9 Be, in the incident energy interval 22 ≤ E LAB ≤ 64 MeV. Evidences are presented that highly damped binary processes observed in these systems are originated from a fusion-fission process rather than a dinuclear ''orbiting'' mechanism. The relative importance of the fusion-fission process in these very light systems is demonstrated both by the experimental results, which indicate a statistically balanced compound nucleus fission process occurrence, and theoretical calculations. (L.C.J.A.)

Post-scission fission theory: Neutron emission in fission

International Nuclear Information System (INIS)

Madland, D.G.

1997-01-01

A survey of theoretical representations of two of the observables in neutron emission in fission is given, namely, the prompt fission neutron spectrum N (E) and the average prompt neutron multiplicity bar ν p . Early representations of the two observables are presented and their deficiencies are discussed. This is followed by summaries and examples of recent theoretical models for the calculation of these quantities. Emphasis is placed upon the predictability and accuracy of the recent models. In particular, the dependencies of N (E) and bar ν p upon the fissioning nucleus and its excitation energy are treated. Recent work in the calculation of the prompt fission neutron spectrum matrix N (E, E n ), where E n is the energy of the neutron inducing fission, is then discussed. Concluding remarks address the current status of our ability to calculate these observables with confidence, the direction of future theoretical efforts, and limitations to current (and future) approaches

Fission products collecting devices

International Nuclear Information System (INIS)

Matsumoto, Hiroshi

1979-01-01

Purpose: To enable fission products trap with no contamination to coolants and cover gas by the provision of a fission products trap above the upper part of a nuclear power plant. Constitution: Upon fuel failures in a reactor core, nuclear fission products leak into coolants and move along the flow of the coolants to the coolants above the reactor core. The fission products are collected in a trap container and guided along a pipeline into fission products detector. The fission products detector monitors the concentration of the fission products and opens the downstream valve of the detector when a predetermined concentration of the fission products is detected to introduce the fission products into a waste gas processing device and release them through the exhaust pipe. (Seki, T.)

Nuclear fission and reactions

International Nuclear Information System (INIS)

Anon.

1975-01-01

The nuclear fission research programs are designed to elucidate basic features of the fission process. Specifically, (1) factors determining how nucleons of a fissioning nucleus are distributed between two fission fragments, (2) factors determining kinetic energy and excitation energies of fragments, and (3) factors controlling fission lifetimes. To these ends, fission studies are reported for several heavy elements and include investigations of spontaneous and neutron-induced fission, heavy ion reactions, and high energy proton reactions. The status of theoretical research is also discussed. (U.S.)

Hemi-fused structure mediates and controls fusion and fission in live cells.

Science.gov (United States)

Zhao, Wei-Dong; Hamid, Edaeni; Shin, Wonchul; Wen, Peter J; Krystofiak, Evan S; Villarreal, Seth A; Chiang, Hsueh-Cheng; Kachar, Bechara; Wu, Ling-Gang

2016-06-23

Membrane fusion and fission are vital for eukaryotic life. For three decades, it has been proposed that fusion is mediated by fusion between the proximal leaflets of two bilayers (hemi-fusion) to produce a hemi-fused structure, followed by fusion between the distal leaflets, whereas fission is via hemi-fission, which also produces a hemi-fused structure, followed by full fission. This hypothesis remained unsupported owing to the lack of observation of hemi-fusion or hemi-fission in live cells. A competing fusion hypothesis involving protein-lined pore formation has also been proposed. Here we report the observation of a hemi-fused Ω-shaped structure in live neuroendocrine chromaffin cells and pancreatic β-cells, visualized using confocal and super-resolution stimulated emission depletion microscopy. This structure is generated from fusion pore opening or closure (fission) at the plasma membrane. Unexpectedly, the transition to full fusion or fission is determined by competition between fusion and calcium/dynamin-dependent fission mechanisms, and is notably slow (seconds to tens of seconds) in a substantial fraction of the events. These results provide key missing evidence in support of the hemi-fusion and hemi-fission hypothesis in live cells, and reveal the hemi-fused intermediate as a key structure controlling fusion and fission, as fusion and fission mechanisms compete to determine the transition to fusion or fission.

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

International Nuclear Information System (INIS)

Laptev, Alexander B.; Tovesson, Fredrik; Burgett, Eric; Greife, Uwe; Grimes, Steven; Heffner, Michael D.; Hertel, Nolan E.; Hill, Tony; Isenhower, Donald; Klay, Jennifer L.; Kornilov, Nickolay; Kudo, Ryuho; Loveland, Walter; Massey, Thomas; McGrath, Chris; Pickle, Nathan; Qu, Hai; Sharma, Sarvagya; Snyder, Lucas; Thornton, Tyler; Towell, Rusty S.; Watson, Shon

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 ( 235 U, 239 Pu, 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 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 235 U.

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...

Structure of heavy-ion tracks in zircon

International Nuclear Information System (INIS)

Braunshausen, G.; Bursill, L.A.; Vetter, J.; Spohr, R.

1990-01-01

Gem quality zirconas (ZrSiO 4 ) were irradiated with 14MeV/u Pb ions. Observations of heavy-ion tracks confirmed that fission or heavy-ion irradiation damage is confined to a 50-100 Aangstroem core region, which has undergone a crystalline-glass phase transition. 3 refs., 3 figs

Fission-product yields for thermal-neutron fission of curium-243

International Nuclear Information System (INIS)

Breederland, D.G.

1982-01-01

Cumulative fission yields for 25 gamma rays emitted during the decay of 23 fission products produced by thermal-neutron fission of 243 Cm have been determined. Using Ge(Li) spectroscopy, 33 successive pulse-height spectra of gamma rays emitted from a 77-ng sample of 243 Cm over a period of approximately two and one-half months were analyzed. Reduction of these spectra resulted in the identification and matching of gamma-ray energies and half-lives to specific radionuclides. Using these results, 23 cumulative fission-product yields were calculated. Only those radionuclides having half-lives between 6 hours and 65 days were observed. Prior to this experiment, no fission-product yields had been recorded for 243 Cm

Correlation of recent fission product release data

International Nuclear Information System (INIS)

Kress, T.S.; Lorenz, R.A.; Nakamura, T.; Osborne, M.F.

1989-01-01

For the calculation of source terms associated with severe accidents, it is necessary to model the release of fission products from fuel as it heats and melts. Perhaps the most definitive model for fission product release is that of the FASTGRASS computer code developed at Argonne National Laboratory. There is persuasive evidence that these processes, as well as additional chemical and gas phase mass transport processes, are important in the release of fission products from fuel. Nevertheless, it has been found convenient to have simplified fission product release correlations that may not be as definitive as models like FASTGRASS but which attempt in some simple way to capture the essence of the mechanisms. One of the most widely used such correlation is called CORSOR-M which is the present fission product/aerosol release model used in the NRC Source Term Code Package. CORSOR has been criticized as having too much uncertainty in the calculated releases and as not accurately reproducing some experimental data. It is currently believed that these discrepancies between CORSOR and the more recent data have resulted because of the better time resolution of the more recent data compared to the data base that went into the CORSOR correlation. This document discusses a simple correlational model for use in connection with NUREG risk uncertainty exercises. 8 refs., 4 figs., 1 tab

Probability of ternary fission of 93Nb andnat Ag nuclei induced by 0.8-1.8 GeV photons

International Nuclear Information System (INIS)

Lima, D.A. de; Milomen, W.C.C.; Tavares, O.A.P.

1989-01-01

The yields of ternary fission of 93 Nb and nat Ag nuclei induced by bremsstrahlung photons of 0.8, 1.0, 1.4 and 1.8 GeV end-point energies have been measured by using the 2 Π-forward geometry with thick target metal foils in contact with makrofol polycarbonate sheets as fission-track detectors. Absolute mean cross sections per photon in the range 0.8-1.8 GeV have been obtained as 0.3 ± 0.3 μb and 0.5 ± μb, respectively, for 93 Nb and nat Ag nuclei. These correspond to a probability of ternary fission of approx. 10 -5 for both nuclei. Results are discussed and compared with previous ternary fission data obtained for nuclei of A [pt

Energy released in fission

International Nuclear Information System (INIS)

James, M.F.

1969-05-01

The effective energy released in and following the fission of U-235, Pu-239 and Pu-241 by thermal neutrons, and of U-238 by fission spectrum neutrons, is discussed. The recommended values are: U-235 ... 192.9 ± 0.5 MeV/fission; U-238 ... 193.9 ± 0.8 MeV/fission; Pu-239 ... 198.5 ± 0.8 MeV/fission; Pu-241 ... 200.3 ± 0.8 MeV/fission. These values include all contributions except from antineutrinos and very long-lived fission products. The detailed contributions are discussed, and inconsistencies in the experimental data are pointed out. In Appendix A, the contribution to the total useful energy release in a reactor from reactions other than fission are discussed briefly, and in Appendix B there is a discussion of the variations in effective energy from fission with incident neutron energy. (author)

The evaluation for reference fission yield of 238U fission

International Nuclear Information System (INIS)

Liang Qichang; Liu Tingjin

1998-01-01

In the fission yield data evaluation and measurement, the reference yield is very important, good or poor recommended or measurement values depend upon the reference data to a great extent. According to the CRP's requirement, the evaluation of reference fission yields have been and will be carried out in CNDC, as a part of the whole work (contract No.9504/R 0 /Regular Budget Fund), the evaluation for 29 reference fission yields of 15 product nuclides from 238 U fission have been completed

Study of electron-capture delayed fission in Am-232

International Nuclear Information System (INIS)

Kreek, S.A.; Hall, H.L.; Hoffman, D.C.; Strellis, D.; Gregorich, K.E.

1996-01-01

An automated x-ray-fission coincidence system was designed and constructed by LLNL and Lawrence Berkeley National Laboratory (LBNL) for use inside the Gammasphere high efficiency gamma-ray detector array at LBNL. The x-ray-fission coincidence apparatus detection station consists of two surface barrier detectors (for detection of fission fragments) and two high-purity Ge (HPGe) planar x-ray detectors (for measurement of x-rays and low-energy gamma rays). The detection station is placed inside Gammasphere at the 88-Inch Cyclotron at LBNL and used in conjunction with Gammasphere to measure the x-rays, low-energy gamma-rays and fission fragments resulting from the ECDF process. A series of collaborative experiment between LLNL, LBNL, and LANL utilizing various components of the x-ray-fission coincidence apparatus to measure x-rays and gamma-rays in the decay of a stationary 252 Cf source were performed to test the various components of the x-ray-fission coincidence apparatus. The test experiments have been completed and the data is currently being analyzed by LBNL. Preliminary test results indicate that the system performed better than expected (e.g., the x-ray detectors performed better than expected with no evidence of microphonic noise that would reduce the photon energy resolution)

Denudation and uplift of the Mawson Escarpment (eastern Lambert Graben, Antarctica) as indicated by apatite fission track data and geomorphological observation

Science.gov (United States)

Lisker, F.; Gibson, H.; Wilson, C.J.; Läufer, A.

2007-01-01

Analysis of three vertical profiles from the southern Mawson Escarpment (Lambert Graben) reveals apatite fission track (AFT) ages ranging from 102±20 to 287±23 Ma and mean lengths of 12.2 to 13.0 μm. Quantitative thermal histories derived from these data consistently indicate onset of slow cooling below 110°C began sometime prior to 300 Ma, and a second stage of rapid cooling from paleotemperatures up to ≤100°C to surface temperatures occurred in the Late Cretaceous – Paleocene. The first cooling phase refers to Carboniferous – Jurassic basement denudation up to 5 km associated with the initial rifting of the Lambert Graben. The presence of the ancient East Antarctic Erosion Surface and rapid Late Cretaceous – Paleocene cooling indicate a second denudational episode during which up to 4.5 km of sedimentary cover rocks were removed, and that is likely linked to the Cretaceous Gondwana breakup between Antarctica and India and subsequent passive continental margin formation.

Fission yield covariance generation and uncertainty propagation through fission pulse decay heat calculation

International Nuclear Information System (INIS)

Fiorito, L.; Diez, C.J.; Cabellos, O.; Stankovskiy, A.; Van den Eynde, G.; Labeau, P.E.

2014-01-01

Highlights: • Fission yield data and uncertainty comparison between major nuclear data libraries. • Fission yield covariance generation through Bayesian technique. • Study of the effect of fission yield correlations on decay heat calculations. • Covariance information contribute to reduce fission pulse decay heat uncertainty. - Abstract: Fission product yields are fundamental parameters in burnup/activation calculations and the impact of their uncertainties was widely studied in the past. Evaluations of these uncertainties were released, still without covariance data. Therefore, the nuclear community expressed the need of full fission yield covariance matrices to be able to produce inventory calculation results that take into account the complete uncertainty data. State-of-the-art fission yield data and methodologies for fission yield covariance generation were researched in this work. Covariance matrices were generated and compared to the original data stored in the library. Then, we focused on the effect of fission yield covariance information on fission pulse decay heat results for thermal fission of 235 U. Calculations were carried out using different libraries and codes (ACAB and ALEPH-2) after introducing the new covariance values. Results were compared with those obtained with the uncertainty data currently provided by the libraries. The uncertainty quantification was performed first with Monte Carlo sampling and then compared with linear perturbation. Indeed, correlations between fission yields strongly affect the uncertainty of decay heat. Eventually, a sensitivity analysis of fission product yields to fission pulse decay heat was performed in order to provide a full set of the most sensitive nuclides for such a calculation

Computer program FPIP-REV calculates fission product inventory for U-235 fission

Science.gov (United States)

Brown, W. S.; Call, D. W.

1967-01-01

Computer program calculates fission product inventories and source strengths associated with the operation of U-235 fueled nuclear power reactor. It utilizes a fission-product nuclide library of 254 nuclides, and calculates the time dependent behavior of the fission product nuclides formed by fissioning of U-235.

Separation of fission products by the use of recoil; Separation des produits de fission par utilisation du recul

Energy Technology Data Exchange (ETDEWEB)

Henry, R; Beydon, J; Bardy, A [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

We have studied fission recoil in U{sub 3}O{sub 8} organic solvent mixtures. The organic phase chosen was first naphtalene then terphenyl. Graphite and activated carbon were also tried out as recoil media. We first verified that the fission fragments are ejected from the uranium oxide particles under our experimental conditions. The retention phenomenon observed is due to an adsorption occurring either during irradiation or during the chemical treatment. Using naphthalene or terphenyl, the individual separation of the fission products has made it possible to show the influence of the chemical nature of the recoil medium on the retention of each fission product. We put forward a hypothesis concerning this phenomenon: experiments carried out using 'scavengers', together with kinetic studies make it possible to explain the retention phenomenon and to choose the most favorable conditions for reducing this retention to a low value. The thermal recombination kinetics demonstrate the influence of the fission ion charge on the final value of the retention for a given temperature. The origins of this thermal recombination are discussed. (author) [French] On a etudie le recul de fission dans les melanges U{sub 3}0{sub 8}, phase organique. La phase organique choisie a ete le naphtalene puis le terphenyle. Le graphite et le charbon actif ont egalement ete essayes comme milieux de recul. On a d'abord determine que les fragments de fission sortent des particules d'oxyde d'uranium avec un rendement de 100 pour cent dans nos conditions experimentales. Le phenomene de retention observe est du a une adsorption ayant lieu pendant l'irradiation ou pendant le traitement chimique. Dans le naphtalene et le terphenyle, la separation individuelle des produits de fission a permis de mettre en evidence l'influence de la nature chimique du milieu de recul sur la retention de chaque produit de fission. On avance une hypothese sur ce phenomene: des experiences effectuees avec des 'scavengers

Application of fission track technique for estimation of uranium concentration in drinking waters of Punjab

International Nuclear Information System (INIS)

Prabhu, S.P.; Raj, Sanu S.; Sawant, P.D.; Kumar, Ajay; Sarkar, P.K.; Tripathi, R.M.

2010-01-01

Full text: Drinking water samples were collected from four different districts, namely Bhatinda, Mansa, Faridkot and Firozpur, of Punjab for ascertaining the U(nat.) concentrations. The samples were collected from bore wells, hand pumps, tube wells and treated municipal water supply. All these samples (235 nos.) collected were preserved and processed by following the international standard protocol and analyzed by Laser Fluorimetry. Results of analysis by laser fluorimetry have been already reported. To ensure accuracy of the data obtained by laser fluorimetry, few samples (10 nos) from each district were analyzed by alpha spectrometry as well as by fission track analysis (FTA) technique. FTA in solution media for uranium has been already standardized in Bioassay laboratory of Health Physics Division. Few of drinking water sample was directly transferred to polythene tube sealed at one end. Lexan detector with proper identification mark was immersed in the samples and the other open end of the tube was also heat-sealed. Two tubes containing samples and one containing uranium standard (80 ppb) were irradiated in the Pneumatic Carrier Facility (PCF) of DHRUVA reactor. The Lexan detectors were then chemically etched and tracks were counted under an optical microscope at 400X magnification. Concentration of uranium in sample was determined by comparison technique. Quality assurance was carried out by replicate analysis and by analysis of standard reference materials. Uranium concentration in these samples ranged from 3.2 to 60.5 ppb with an average of 28.8 ppb. A t-test analysis for paired data was done to compare the results obtained by FTA and those obtained by laser fluorimeter. The calculated value for t is -1.19, which is greater than the tabulated value of t for 40 observations (-2.02 at 95% confidence level). This shows that the results of the measurements carried out by the FTA and laser fluorimetry are not significantly different. The preliminary studies

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.)

Experimental examination of ternary fission in nuclear track emulsion

Czech Academy of Sciences Publication Activity Database

Mamatkulov, K. Z.; Ambrožová, Iva; Artemenkov, D. A.; Bradnova, V.; Firu, E.; Haiduc, M.; Kákona, Martin; Kattabekov, R. R.; Marey, A.; Neagu, A.; Ploc, Ondřej; Rusakova, V. V.; Stanoeva, R.; Turek, Karel; Zaitsev, A. A.; Zarubin, P. I.; Zarubina, I. G.

2017-01-01

Roč. 48, č. 6 (2017), s. 910-913 ISSN 1063-7796 Institutional support: RVO:61389005 Keywords : angular correlation * nuclear track emulsion Subject RIV: BF - Elementary Particles and High Energy Physics OBOR OECD: Particles and field physics Impact factor: 0.681, year: 2016

Mica fission detectors

International Nuclear Information System (INIS)

Wong, C.; Anderson, J.D.; Hansen, L.; Lehn, A.V.; Williamson, M.A.

1977-01-01

The present development status of the mica fission detectors is summarized. It is concluded that the techniques have been refined and developed to a state such that the mica fission counters are a reliable and reproducible detector for fission events

Fission-track constraints on the thermal and tectonic evolution of the Apuseni Mountains (Romania)

Science.gov (United States)

Kounov, Alexandre; Schmid, Stefan M.

2013-01-01

New zircon and apatite fission-track (FT) data, including apatite thermal modelling, are combined with an extensive literature survey and reconnaissance-type structural fieldwork in the Eastern Apuseni Mountains. This leads to a better understanding of the complex structural and thermal history of a key area at the boundary between two megatectonic units in the Balkan peninsula, namely the Tisza and Dacia Mega-Units. Following Late Jurassic obduction of the Transylvanian ophiolites onto a part of the Dacia Mega-Unit, that is, the Biharia nappe system, both units were buried to a minimum of 8 km during late Early Cretaceous times when these units were underthrust below the Tisza Mega-Unit consisting of the present-day Codru and Bihor nappe systems. Tisza formed the upper plate during Early Cretaceous (`Austrian') east-facing orogeny. Turonian to Campanian zircon FT cooling ages (95-71 Ma) from the Bihor and Codru nappe systems and the Biharia and Baia de Arieş nappes (at present the structurally lowest part of the Dacia Mega-Unit) record exhumation that immediately followed a second Cretaceous-age (i.e. Turonian) orogenic event. Thrusting during this overprinting event was NW-facing and led to the overall geometry of the present-day nappe stack in the Apuseni Mountains. Zircon FT ages, combined with thermal modelling of the apatite FT data, show relatively rapid post-tectonic cooling induced by a third shortening pulse during the latest Cretaceous (`Laramian' phase), followed by slower cooling across the 120°-60 °C temperature interval during latest Cretaceous to earliest Paleogene times (75-60 Ma). Cenozoic-age slow cooling (60-40 Ma) was probably related to erosional denudation postdating `Laramian' large-scale updoming.

Measurements of fission yields

International Nuclear Information System (INIS)

Denschlag, H.O.

2000-01-01

After some historical introductory remarks on the discovery of nuclear fission and early fission yield determinations, the present status of knowledge on fission yields is briefly reviewed. Practical and fundamental reasons motivating the pursuit of fission yield measurements in the coming century are pointed out. Recent results and novel techniques are described that promise to provide new interesting insights into the fission process during the next century. (author)

Radiochemical studies on fission

Energy Technology Data Exchange (ETDEWEB)

None

1973-07-01

Research progress is reported on nuclear chemistry; topics considered include: recoil range and kinetic energy distribution in the thermal neutron ftssion of /sup 245/Cm; mass distribution and recoil range measurements in the reactor neutron-induced fission of /sup 232/U; fission yields in the thermal neutron fission of /sup 241/PU highly asymmetric binary fission of uranium induced by reactor neutrons; and nuclear charge distribution in low energy fission. ( DHM)

Geology and zircon fission track ages of volcanic rocks in the western part of Hoshino gold area, Fukuoka Prefecture, Japan

Energy Technology Data Exchange (ETDEWEB)

Belhadi, Ahmed; Himeno, Osamu; Watanabe, Koichiro; Izawa, Eiji [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering

1999-12-01

The Hoshino gold area is located in the western part of the Hohi volcanic zone, northern Kyushu. Volcanic rocks in this area vary from andesitic rocks in the north to dacite and rhyolite in the South. The basement is constituted by metamorphic rocks of pre-Cretaceous age. The volcanic rocks of Pliocene age were subdivided into eight volcanic units. Seven fission track ages of zircons from five volcanic units have been determined, using the external detector method. The age data obtained, combined with some previously reported ages, show that two main volcanic activities have occurred in the area. The first volcanic activity took place around 4.3 Ma, and resulted into the deposition of the Hoshino Andesite and the Ikenoyama Conglomerate. The second main volcanism started around 3.5 Ma, and was characterized by the eruption of the Shakadake Andesite and the Reiganji Andesite at the early stage, then, by more acidic rocks of the Takeyama Andesite, the Hyugami Dacite and the Kuroki Rhyolite at the later stage. The main volcanism in the area ceased around 2.6 Ma. (author)

Measurement of prompt fission gamma-ray spectra in fast neutron-induced fission

International Nuclear Information System (INIS)

Laborie, J.M.; Belier, G.; Taieb, J.

2012-01-01

Knowledge of prompt fission gamma-ray emission has been of major interest in reactor physics for a few years. Since very few experimental spectra were ever published until now, new measurements would be also valuable to improve our understanding of the fission process. An experimental method is currently being developed to measure the prompt fission gamma-ray spectrum from some tens keV up to 10 MeV at least. The mean multiplicity and total energy could be deduced. In this method, the gamma-rays are measured with a bismuth germanate (BGO) detector which has the advantage to present a high P/T ratio and a high efficiency compared to other gamma-ray detectors. The prompt fission neutrons are rejected by the time of flight technique between the BGO detector and a fission trigger given by a fission chamber or a scintillating active target. Energy and efficiency calibration of the BGO detector were carried out up to 10.76 MeV by means of the Al-27(p, gamma) reaction. First prompt fission gamma-ray spectrum measurements performed for the spontaneous fission of Cf-252 and for 1.7 and 15.6 MeV neutron-induced fission of U-238 at the CEA, DAM, DIF Van de Graaff accelerator, will be presented. (authors)

Nuclear tracks, Sm isotopes and neutron capture effects in the Elephant Morraine shergottite

International Nuclear Information System (INIS)

Rajan, R.S.; Lugmair, G.; Tamhane, A.S.; Poupeau, G.

1986-01-01

Nuclear track studies, uranium concentration measurements and Sm-isotope studies have been performed on both lithologies A and B of the Elephant Morraine shergottite, EETA 79001. Track studies show that EETA 79001 was a rather small object in space with a preatmospheric radius of 12+-2 cm, corresponding to a preatmospheric mass of 28+-13 kg. Phosphates have U-concentrations ranging from 0.3 to 1.3 ppm. There are occasional phosphates with excess fission tracks, possibly produced from neutron induced fission of U and Th, during the regolith exposure in the shergottite parent body (SPB). Sm-isotope studies, while not showing any clear cut excess in 150 Sm, enable us to derive meaningful upper limits to thermal neutron fluences of 2 to 3x10 15 n/cm 2 , during a possible regolith irradiation. These limits are consistent with the track data and also enable us to derive an upper limit to the neutron exposure age of EETA 79001 of 55 Myr in the SPB regolith. (author)

Nuclear tracks, Sm isotopes and neutron capture effects in the Elephant Morraine shergottite

International Nuclear Information System (INIS)

Rajan, R.S.; Lugmair, G.; Tamhane, A.S.; Poupeau, G.

1985-01-01

Nuclear track studies, uranium concentration measurements and Sm-isotope studies have been performed on both lithologies A and B of the Elephant Morraine Shergottite, EETA 79001. Track studies show that EETA 79001 was a rather small object in space with a preatmospheric radius of 12 +-2cm, corresponding to a preatmospheric mass of 28 +- 13 kg. U-concentrations measurements indicate that phosphates have concentrations ranging from 0.3 to 1.3 ppm. There are occasional phosphates with excess fission tracks, possibly produced from neutron induced fission of U and Th, during the regolith exposure in the shergottite parent body (SPB). Sm-isotope studies, while not showing any clear cut excess in 150 Sm, enable us to derive meaningful upper limits to thermal neutron fluences of 2 to 3x10 15 n/cm 2 , during a possible regolith irradiation. These limits are consistent with that required to explain the track data and also enable us to derive an upper limit to the neutron exposure age of EETA 79001 of 55 Myr in the SPB regolith. (Author) [pt

Nuclear track radiography of 'hot' aerosol particles

CERN Document Server

Boulyga, S F; Kievets, M K; Lomonosova, E M; Zhuk, I V; Yaroshevich, O I; Perelygin, V P; Petrova, R I; Brandt, R; Vater, P

1999-01-01

Nuclear track radiography was applied to identify aerosol 'hot' particles which contain elements of nuclear fuel and fallout after Chernobyl NPP accident. For the determination of the content of transuranium elements in radioactive aerosols the measurement of the alpha-activity of 'hot' particles by SSNTD was used in this work, as well as radiography of fission fragments formed as a result of the reactions (n,f) and (gamma,f) in the irradiation of aerosol filters by thermal neutrons and high energy gamma quanta. The technique allowed the sizes and alpha-activity of 'hot' particles to be determined without extracting them from the filter, as well as the determination of the uranium content and its enrichment by sup 2 sup 3 sup 5 U, sup 2 sup 3 sup 9 Pu and sup 2 sup 4 sup 1 Pu isotopes. Sensitivity of determination of alpha activity by fission method is 5x10 sup - sup 6 Bq per particle. The software for the system of image analysis was created. It ensured the identification of track clusters on an optical imag...

Nuclear track radiography of 'hot' aerosol particles

International Nuclear Information System (INIS)

Boulyga, S.F.; Kievitskaja, A.I.; Kievets, M.K.; Lomonosova, E.M.; Zhuk, I.V.; Yaroshevich, O.I.; Perelygin, V.P.; Petrova, R.; Brandt, R.; Vater, P.

1999-01-01

Nuclear track radiography was applied to identify aerosol 'hot' particles which contain elements of nuclear fuel and fallout after Chernobyl NPP accident. For the determination of the content of transuranium elements in radioactive aerosols the measurement of the α-activity of 'hot' particles by SSNTD was used in this work, as well as radiography of fission fragments formed as a result of the reactions (n,f) and (γ,f) in the irradiation of aerosol filters by thermal neutrons and high energy gamma quanta. The technique allowed the sizes and alpha-activity of 'hot' particles to be determined without extracting them from the filter, as well as the determination of the uranium content and its enrichment by 235 U, 239 Pu and 241 Pu isotopes. Sensitivity of determination of alpha activity by fission method is 5x10 -6 Bq per particle. The software for the system of image analysis was created. It ensured the identification of track clusters on an optical image of the SSNTD surface obtained through a video camera and the determination of size and activity of 'hot' particles

Estimation of the geological age of oceanic basalts by track method

International Nuclear Information System (INIS)

Komarov, A.N.; Krylov, A.Ya.

1977-01-01

The method is described of the determination of the thermostability of tracks applied to oceanic basalts and the comparison is carried out of age values obtained for the same samples by the track method and by the potassium-argon method. The obtained results allow to consider that the track method is quite practicable for the dating of oceanic basalts on the condition that natural annealing of a part of tracks of the spontaneous uranium fission is taken into accout. For glasses of the other origin - tektites - such approach results in the agreement of the obtained values with the results of potassium-argon method

Fast fission phenomena

International Nuclear Information System (INIS)

Gregoire, Christian.

1982-03-01

Experimental studies of fast fission phenomena are presented. The paper is divided into three parts. In the first part, problems associated with fast fission processes are examined in terms of interaction potentials and a dynamic model is presented in which highly elastic collisions, the formation of compound nuclei and fast fission appear naturally. In the second part, a description is given of the experimental methods employed, the observations made and the preliminary interpretation of measurements suggesting the occurence of fast fission processes. In the third part, our dynamic model is incorporated in a general theory of the dissipative processes studied. This theory enables fluctuations associated with collective variables to be calculated. It is applied to highly inelastic collisions, to fast fission and to the fission dynamics of compound nuclei (for which a schematic representation is given). It is with these calculations that the main results of the second part can be interpreted [fr

What can we learn from the fission time of the super-heavy elements?

OpenAIRE

Boilley, D.; Marchix, A.; Wilgenbus, D.; Lallouet, Y.; Gimbert, F.; Abe, Y.

2007-01-01

International audience; Recent experiments performed at GANIL with a crystal blocking technique have shown direct evidences of long fission times in the Super-Heavy Elements (SHE) region. Aimed to localize the SHE island of stability, can these experiments give access to the fission barrier and then to the shell-correction energy? In this paper, we calculate the fission time of heavy elements by using a new code, KEWPIE2, devoted to the study of the SHE.We also investigate the effect of poten...

Interaction of 80 MeV PI+ with different targets: Track detector studies

Energy Technology Data Exchange (ETDEWEB)

Tabassum, L; Chohan, A S [Government Coll., Lahore. (Pakistan) Deptt. of Physics Khan, H.A. (Pakistan Inst. of Nuclear Science and Technology, Islamabad (Pakistan). Nuclear Engineering Div.)

1990-04-01

CR-39 and mica track detectors have been used in the study of the interactions of 80 MeV PI+ with thin targets of Bi, Pb, Ho, Sb. The binary fission cross sections, the length and angular distributions of etched tracks have been obtained. The cross-section values obtained by using CR-39 are higher as compared to those obtained with mica. (author).

Interaction of 80 MeV PI+ with different targets: Track detector studies

International Nuclear Information System (INIS)

Tabassum, L.; Chohan, A.S.

1990-01-01

CR-39 and mica track detectors have been used in the study of the interactions of 80 MeV PI+ with thin targets of Bi, Pb, Ho, Sb. The binary fission cross sections, the length and angular distributions of etched tracks have been obtained. The cross-section values obtained by using CR-39 are higher as compared to those obtained with mica. (author)

Nuclear fission

International Nuclear Information System (INIS)

Kodama, T.

1981-01-01

The nuclear fission process is pedagogically reviewed from a macroscopic-microscopic point of view. The Droplet model is considered. The fission dynamics is discussed utilizing path integrals and semiclassical methods. (L.C.) [pt

Experimental survey of the potential energy surfaces associated with fission

International Nuclear Information System (INIS)

Britt, H.C.

1980-01-01

Progress in the experimental determination of the properties of the potential energy surface associated with fission is reviewed. The importance of nuclear symmetry effects on the calculation of fission widths is demonstrated. Evidence is presented for the fragmentation of the mass-asymmetric second barrier in the thorium region and the axial asymmetric first barrier in the californium region. Detailed analyses of experimental data suggest the presence of two parallel second barriers; the normal mass-asymmetric, axial-symmetric barrier and a slightly higher mass-symmetric, axial-asymmetric barrier. Experimental barrier parameters are determined systematically and compared with calculations from various theoretical models. Techniques for expanding fission probability measurements to higher energies are discussed. (author)

Electromagnetic fission of 238U at 600 and 1000 MeV per nucleon

International Nuclear Information System (INIS)

Rubehn, T.; Mueller, W.F.J.; Bassini, R.; Begemann-Blaich, M.; Blaich, T.; Gross, C.; Imme, G.; Iori, I.; Kunde, G.J.; Kunze, W.D.; Lindenstruth, V.; Lynen, U.; Moehlemkamp, T.; Moretto, L.G.; Ocker, B.; Pochodzalla, J.; Raciti, G.; Reito, S.; Sann, H.; Schuettauf, A.; Serfling, V.; Trautmann, W.; Trzcinski, A.; Verde, G.; Woerner, A.; Zude, E.; Zwieglinski, B.

1995-05-01

Electromagnetic fission of 238 U projectiles at E/A=600 and 1000 MeV was studied with the ALADIN spectrometer at the heavy-ion synchrotron SIS. Seven different targets (Be, C, Al, Cu, In, Au and U) were used. By considering only those fission events where the two charges added up to 92, most of the nuclear interactions were excluded. The nuclear contributions to the measured fission cross sections were determined by extrapolating from beryllium to the heavier targets with the concept of factorization. The obtained cross sections for electromagnetic fission are well reproduced by extended Weizsaecker-Williams calculations which include E1 and E2 excitations. The asymmetry of the fission fragments' charge distribution gives evidence for the excitation of the double giant-dipole resonance in uranium. (orig.)

Prompt fission neutron spectra of n + 235U above the (n, nf) fission threshold

International Nuclear Information System (INIS)

Shu Nengchuan; Chen Yongjing; Liu Tingjin; Jia Min

2015-01-01

Calculations of prompt fission neutron spectra (PFNS) from the 235 U(n, f) reaction were performed with a semi-empirical method for En = 7.0 and 14.7 MeV neutron energies. The total PFNS were obtained as a superposition of (n, xnf) pre-fission neutron spectra and post-fission spectra of neutrons which were evaporated from fission fragments, and these two kinds of spectra were taken as an expression of the evaporation spectrum. The contributions of (n, xnf) fission neutron spectra on the calculated PFNS were discussed. The results show that emission of one or two neutrons in the (n, nf) or (n, 2nf) reactions influences the PFNS shape, and the neutron spectra of the (n, xnf) fission-channel are soft compared with the neutron spectra of the (n, f) fission channel. In addition, analysis of the multiple-chance fission component showed that second-chance fission dominates the PFNS with an incident neutron energy of 14.7 MeV whereas first-chance fission dominates the 7 MeV case. (authors)

Fission product yields

International Nuclear Information System (INIS)

Valenta, V.; Hep, J.

1978-01-01

Data are summed up necessary for determining the yields of individual fission products from different fissionable nuclides. Fractional independent yields, cumulative and isobaric yields are presented here for the thermal fission of 235 U, 239 Pu, 241 Pu and for fast fission (approximately 1 MeV) of 235 U, 238 U, 239 Pu, 241 Pu; these values are included into the 5th version of the YIELDS library, supplementing the BIBFP library. A comparison is made of experimental data and possible improvements of calculational methods are suggested. (author)

Modifications in track registration response of PADC detector by energetic protons

CERN Document Server

Dwivedi, K K; Fink, D; Mishra, R; Tripathy, S P; Kulshreshtha, A; Khathing, D T

1999-01-01

It has been well established that different ionising radiations modify the track registration properties of dielectric solids. In an effort to study the response of Polyallyl diglycol carbonate (PADC Homalite) detector towards fission fragment, PADC detectors were exposed to 10 sup 4 Gy dose of 62 MeV protons and then one set of samples were exposed to fission fragments from a sup 2 sup 5 sup 2 Cf source. Two of these detectors were containing a thin layer of Buckminsterfullerene (C sub 6 sub 0). The study of the etched tracks by Leitz Optical Microscope reveals that the track diameters are enhanced by more than 70% in the proton irradiated zone as compared to that in the unirradiated zone. Scanning Electron Microscopy was performed after etching the sample in 6 N NaOH at 55 deg. C for different etching times, to study the details of the surface modifications due to proton irradiation of PADC detectors with and without C sub 6 sub 0 layer. Our observations revealed that the diameters and density of proton tra...

HAC and fission reactors

International Nuclear Information System (INIS)

Fujiwara, I.; Moriyama, H.; Tachikawa, E.

1984-01-01

In the fission process, newly formed fission products undergo hot atom reactions due to their energetic recoil and abnormal positive charge. The hot atom reactions of the fission products are usually accompanied by secondary effects such as radiation damage, especially in condensed phase. For reactor safety it is valuable to know the chemical behaviour and the release behaviour of these radioactive fission products. Here, the authors study the chemical behaviour and the release behaviour of the fission products from the viewpoint of hot atom chemistry (HAC). They analyze the experimental results concerning fission product behaviour with the help of the theories in HAC and other neighboring fields such as radiation chemistry. (Auth.)

Pb, U, Ti, Hf and Zr distributions in zircons determined by proton microprobe and fission track techniques

International Nuclear Information System (INIS)

Clark, G.J.; Gulson, B.L.; Cookson, J.A.

1979-01-01

A proton microprobe has been used to determine Pb, Tl, Hf and Zr distributions across four single zircon crystals separated from a 'rapakivi' granite. The Pb and Zr data are quantitative: Pb and Tl concentrations were below the measurable limits for determinations in situ by most other techniques. The distribution of U in the same crystals was determined by the fission track technique. Limits on precision of U allow only a qualitative correlation of U and Pb, whereas the Tl and Pb correlation is more exactly determined. Zircons with distinct cores and overgrowths exhibited uniform Zr and Hf concentrations across the crystals, whereas the high U rims and 'inclusions' (domains) also had high Tl and Pb contents. Since almost all the Pb in these zircons is derived by radioactive decay of U, the Tl substitution has paralleled that of U. The results indicate that the high U domains are 'hot spots' rather than a separate mineral phase. The strong positive correlation of U and Pb indicates that there is little U daughter product migration relative to U, within the crystal. However, for the zircon population investigated here, the data are equivocal on the question of whether U addition to zircon crystals is associated with new zircon growth or not. In either case, the heterogeneous U and Pb distributions complicate any interpretations of U-Pb isotopic analysis for such zircon populations. (author)

Fission cross-section calculations and the multi-modal fission model

International Nuclear Information System (INIS)

Hambsch, F.J.

2004-01-01

New, self consistent, neutron-induced reaction cross section calculations for 235,238 U, 237 Np have been performed. The statistical model code STATIS was improved to take into account the multimodality of the fission process. The three most dominant fission modes, the two asymmetric standards I (S1) and standard II (S2) modes and the symmetric superlong (SL) mode have been taken into account. De-convoluted fission cross sections for those modes for 235,238 U(n,f) and 237 Np(n,f) based on experimental branching ratios, were calculated for the first time up to the second chance fission threshold. For 235 U(n,f), the calculations being made up to 28 MeV incident neutron energy, higher fission chances have been considered. This implied the need for additional calculations for the neighbouring isotopes. As a side product also mass yield distributions could be calculated at energies hitherto not accessible by experiment. Experimental validation of the predictions is being envisaged

Fission Research at IRMM

Directory of Open Access Journals (Sweden)

Al-Adili A.

2010-03-01

Full Text Available Fission Research at JRC-IRMM has a longstanding tradition. The present paper is discussing recent investigations of fission fragment properties of 238 U(n,f, 234 U(n,f, prompt neutron emission in fission of 252 Cf(SF as well as the prompt fission neutron spectrum of 235 U(n,f and is presenting the most important results.

Study on the effect factor of the absolute fission rates measured by depleted uranium fission chamber

International Nuclear Information System (INIS)

Jiang Li; Liu Rong; Wang Dalun; Wang Mei; Lin Jufang; Wen Zhongwei

2003-01-01

The absolute fission rates was measured by the depleted uranium fission chamber. The efficiency of the fission fragments recorded in the fission chamber was analyzed. The factor influencing absolute fission rates was studied in the experiment, including the disturbing effect between detectors and the effect of the structural of the fission chamber, etc

Assessment of the high temperature fission chamber technology for the French fast reactor program

Energy Technology Data Exchange (ETDEWEB)

Jammes, C.; Filliatre, P.; Geslot, B.; Domenech, T.; Normand, S. [Commissariat a l' Energie Atomique, CEA (France)

2011-07-01

High temperature fission chambers are key instruments for the control and protection of the sodium-cooled fast reactor. First, the developments of those neutron detectors, which are carried out either in France or abroad are reviewed. Second, the French realizations are assessed with the use of the technology readiness levels in order to identify tracks of improvement. (authors)

Investigation of short-living fission products from the spontaneous fission of Cf-252

International Nuclear Information System (INIS)

Klonk, H.

1976-01-01

In this paper, a method of separating and measuring fission products of Cf-252 is presented. The measurement was achieved by means of γ-spectrometry and thus provides a quantitative analysis with a good separation of the fission products with respect to both atomic number Z and mass number A. The separation of the fission products from the fission source was achieved by means of solid traps. An automatic changing apparatus made it possible to keep irradiation and measuring times short, so even very short-lived fission products could be registered. The quantitative evaluation of primary fission products was made possible by correction according to Bateman equations. With that, the yields of single nuclides and the dispersion of charge can be determined. (orig./WL) [de

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

Studies on the characteristics of nuclear track spark counting for neutron monitoring

International Nuclear Information System (INIS)

Kawai, H.; Koga, T.; Morishima, H.; Niwa, T.; Nishiwaki, Y.

1979-01-01

The fission-track counting method using polycarbonate foil is known to be very effective for neutron monitoring. The detection system consists of a track detector foil placed in contact with a thin layer of fissile material. When the unit is irradiated with neutrons, fission fragments from the fissile material produce tracks in the foil. The foil is then etched chemically to enlarge the tracks to etch-pits, which are counted by an automatic spark counting method suggested by Cross and Tommasino. Spark counting characteristics of the above system using polycarbonate detector foils of different thicknesses and aluminized polyester sheets having different thicknesses of the aluminium which serves as an electrode, and etch-pit sizes in relation to spark counting have been studied. The results obtained are summarized as follows: 1. A growth in etch-pit sizes was observed for etching times of 10 to 50 minutes with Makrofol KG (10 μm thick) and Panlite foils (18 μm thick). As the etching time increased, the number of etch-pits which appeared as round pits increased and the number which appeared rod-like decreased; 2. Round etch-pits seemed to be easily spark-punched; 3. Major and minor diameters of etch-pits produced by fission fragments from the uranium fissile target were larger than those from the thorium target; 4. As the thickness of the Makrofol KG foil increased, the minor diameters of the etch-pits appeared to become smaller and major diameters larger; 5. The foils that appeared to be best suited for routine use were 10 μm thick Makrofol KG or 6 μm thick Lumirror foils. (author)

Cosmic ray-induced spallation recoil tracks in meteoritic phosphates: simulation at the CERN synchrocyclotron

Energy Technology Data Exchange (ETDEWEB)

Perron, C [Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France). Inst. d` Astrophysique; [Museum National d` Histoire Naturelle, 75 - Paris (France)

1994-12-31

Annealed meteoritic phosphate crystals have been irradiated by 600 MeV protons to simulate cosmic ray irradiation in space. Spallation recoil tracks were then revealed, which mimic fission tracks, specially when observed in the SEM. A production yield of 9.3 {+-} 2.2 x 10{sup 8} spallation track per proton has been obtained for merrillite, and a substantially lower value (2.5 per proton) for apatite. A nominal production yield in space of 6 tracks per year has been derived, which may be used for a rough estimate of spallation track densities in chondritic merrillite. (Author).

Signatures of fission dynamics in highly excited nuclei produced in 197AU(800 A MeV) on proton collisions

International Nuclear Information System (INIS)

Benlliure, J.; Armbruster, P.; Bernas, M.

2001-09-01

197 Au(800 A MeV)-on-proton collisions are used to investigate the fission dynamics at high excitation energy. The kinematic properties together with the isotopic identification of the fission fragments allow to determine the mass, charge and excitation energy of the fissioning nucleus at saddle. The comparison of these observables and the measured total fission cross section with model calculations evidences a clear hindrance of fission at high excitation energy that can be explained in terms of nuclear dissipation. Assuming a statistical evaporation for other de-excitation channels than fission, an estimated value of the transient time of fission of (3 ± 1) . 10 -21 s is obtained. (orig.)

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.

The nuclear fission process

International Nuclear Information System (INIS)

Wagemans, C.

1991-01-01

Fifty years after its discovery, the nuclear fission phenomenon is of recurring interest. When its fundamental physics aspects are considered, fission is viewed in a very positive way, which is reflected in the great interest generated by the meetings and large conferences organized for the 50th anniversary of its discovery. From a purely scientific and practical point of view, a new book devoted to the (low energy) nuclear fission phenomenon was highly desirable considering the tremendous amount of new results obtained since the publication of the book Nuclear Fission by Vandenbosch and Huizenga in 1973 (Academic Press). These new results could be obtained thanks to the growth of technology, which enabled the construction of powerful new neutron sources, particle and heavy ion accelerators, and very performant data-acquisition and computer systems. The re-invention of the ionization chamber, the development of large fission fragment spectrometers and sophisticated multiparameter devices, and the production of exotic isotopes also contributed significantly to an improved understanding of nuclear fission. This book is written at a level to introduce graduate students to the exciting subject of nuclear fission. The very complete list of references following each chapter also makes the book very useful for scientists, especially nuclear physicists. The book has 12 chapters covering the fission barrier and the various processes leading to fission as well as the characteristics of the various fission reaction products. In order to guarantee adequate treatment of the very specialized research fields covered, several distinguished scientists actively involved in some of these fields were invited to contribute their expertise as authors or co-authors of the different chapters

Intermediate energy nuclear fission

International Nuclear Information System (INIS)

Hylten, G.

1982-01-01

Nuclear fission has been investigated with the double-kinetic-energy method using silicon surface barrier detectors. Fragment energy correlation measurements have been made for U, Th and Bi with bremsstrahlung of 600 MeV maximum energy. Distributions of kinetic energy as a function of fragment mass are presented. The results are compared with earlier photofission data and in the case of bismuth, with calculations based on the liquid drop model. The binary fission process in U, Yb, Tb, Ce, La, Sb, Ag and Y induced by 600 MeV protons has been investigated yielding fission cross sections, fragment kinetic energies, angular correlations and mass distributions. Fission-spallation competition calculations are used to deduce values of macroscopic fission barrier heights and nuclear level density parameter values at deformations corresponding to the saddle point shapes. We find macroscopic fission barriers lower than those predicted by macroscopic theories. No indication is found of the Businaro Gallone limit expected to occur somewhere in the mass range A = 100 to A = 140. For Ce and La asymmetric mass distributions similar to those in the actinide region are found. A method is described for the analysis of angular correlations between complementary fission products. The description is mainly concerned with fission induced by medium-energy protons but is applicable also to other projectiles and energies. It is shown that the momentum and excitation energy distributions of cascade residuals leading to fission can be extracted. (Author)

A study of commercially-available polyethylene terephthalate (PET) and polycarbonate as nuclear track detector materials

Science.gov (United States)

Espinosa, G.; Golzarri, J. I.; Vazquez-Lopez, C.; Trejo, R.; Lopez, K.; Rickards, J.

2014-07-01

In the study of the sensitivity of materials to be used as nuclear track detectors, it was found that commercial polyethylene terephthalate (PET) from Ciel® water bottles, commercial roof cover polycarbonate, and recycled packaging strips (recycled PET), can be used as nuclear track detectors. These three commercial materials present nuclear tracks when bombarded by 2.27 MeV nitrogen ions produced in a Pelletron particle accelerator, and by fission fragments from a 252Cf source (79.4 and 103.8 MeV), after a chemical etching with a 6.25M KOH solution, or with a 6.25M KOH solution with 20% methanol, both solutions at 60±1°C. As an example, the nitrogen ions deposit approximately 1 keV/nm in the form of ionization and excitation at the surface of PET, as calculated using the SRIM code. The fission fragments deposit up to 9 keV/nm at the surface, in both cases generating sufficient free radicals to initiate the track formation process. However, 5 MeV alpha particles, typical of radon (222Rn) emissions, deposit only 0.12 keV/nm, do not present tracks after the chemical etching process. This valuable information could be very useful for further studies of new materials in nuclear track methodology.

Determination of uranium content in dental porcelains by means of the fission track method and estimation of radiation dose to oral mucosa by radioactive elements

International Nuclear Information System (INIS)

Sairenji, E.; Moriwaki, K.; Shimizu, M.; Noguchi, K.

1980-01-01

Porcelain teeth, some of which contain uranium compounds for aesthetic purpose, have been widely used in dental clinics. Hazardous effects due to uranium radiation have been suggested in recent publications. In the present study uranium concentrations were determined in four major brands of porcelain teeth marketed in Japan using the fission track method, and the absorbed doses to oral tissued were calculated. Average uranium concentrations of the brands studied were determined to be 3.6 ppm (0.33-10 ppm, Japan), 18 ppm (0.69-81 ppm, Japan), 9.4 ppm (2.5-14 ppm, Japan) and 82 ppm (11-205 ppm, U.S.), respectively. The corresponding dose equivalents at the surface of oral mucosal membrane were 2.9 rem yr -1 . 14 rem yr -1 , 7.6 rem yr -1 and 66 rem yr -1 . (author)

Solid-state track recorder neutron dosimetry in light water reactor pressure vessel surveillance mockups

International Nuclear Information System (INIS)

Ruddy, F.H.; Roberts, J.H.; Gold, R.; Preston, C.C.

1984-09-01

Solid-State Track Recorder (SSTR) measurements of neutron-induced fission rates have been made in several pressure vessel mockup facilities as part of the US Nuclear Regulatory Commission's (NRC) Light Water Reactor Pressure Vessel Surveillance Dosimetry Improvement Program (LWR-PV-SDIP). The results of extensive physics-dosimetry measurements made at the Pool Critical Assembly (PCA) at Oak Ridge National Laboratory (ORNL) in Oak Ridge, TN are summarized. Included are 235 U, 238 U, 237 Np and 232 Th fission rates in the PCA 12/13, 8/7, and 4/12 SSC configurations. Additional low power measurements have been made in an engineering mockup at the VENUS critical assembly at CEN-SCK, Mol, Belgium. 237 Np and 238 U fission rates were made at selected locations in the VENUS mockup, which models the in-core and near-core regions of a pressurized water reactor (PWR). Absolute core power measurements were made at VENUS by exposing solid-state track recorders (SSTRs) to polished fuel pellets within in-core fuel pins. 8 references, 4 figures, 10 tables

Progress in fission product nuclear data

International Nuclear Information System (INIS)

Lammer, M.

1984-09-01

This is the tenth issue of a report series on Fission Product Data, which informs us about all the activities in this field, which are planned, ongoing, or have recently been completed. The types of activities included are measurements, compilations and evaluations of: fission product yields (neutron induced and spontaneous fission), neutron reaction cross sections of fission products, data related to the radioactive decay of fission products, delayed neutron data of fission products, lumped fission product data (decay heat, absorption, etc.). There is also a section with recent references relative to fission product nuclear data

New Burnup Calculation System for Fusion-Fission Hybrid System

International Nuclear Information System (INIS)

Isao Murata; Shoichi Shido; Masayuki Matsunaka; Keitaro Kondo; Hiroyuki Miyamaru

2006-01-01

Investigation of nuclear waste incineration has positively been carried out worldwide from the standpoint of environmental issues. Some candidates such as ADS, FBR are under discussion for possible incineration technology. Fusion reactor is one of such technologies, because it supplies a neutron-rich and volumetric irradiation field, and in addition the energy is higher than nuclear reactor. However, it is still hard to realize fusion reactor right now, as well known. An idea of combination of fusion and fission concepts, so-called fusion-fission hybrid system, was thus proposed for the nuclear waste incineration. Even for a relatively lower plasma condition, neutrons can be well multiplied by fission in the nuclear fuel, tritium is thus bred so as to attain its self-sufficiency, enough energy multiplication is then expected and moreover nuclear waste incineration is possible. In the present study, to realize it as soon as possible with the presently proven technology, i.e., using ITER model with the achieved plasma condition of JT60 in JAEA, Japan, a new calculation system for fusion-fission hybrid reactor including transport by MCNP and burnup by ORIGEN has been developed for the precise prediction of the neutronics performance. The author's group already has such a calculation system developed by them. But it had a problem that the cross section libraries in ORIGEN did not have a cross section library, which is suitable specifically for fusion-fission hybrid reactors. So far, those for FBR were approximately used instead in the analysis. In the present study, exact derivation of the collapsed cross section for ORIGEN has been investigated, which means it is directly evaluated from calculated track length by MCNP and point-wise nuclear data in the evaluated nuclear data file like JENDL-3.3. The system realizes several-cycle calculation one time, each of which consists of MCNP criticality calculation, MCNP fixed source calculation with a 3-dimensional precise

On the reproducibility of apatite fission-track plateau-age dating

International Nuclear Information System (INIS)

Poupeau, G.; Baitelli, R.; Berbert, M.; Fonseca, A.

1985-01-01

Duplicate measurements as well as published data show that plateau-age measurements on apatites have a reproducibility - when made in optical microscopy - generally better than +- 5%, which may be accounted for by statistical errors on track density measurement. (Author) [pt

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.

Fission-track ages of the Tokai Group and associate formations in the east coast areas of Ise Bay and their significance in geohistory

International Nuclear Information System (INIS)

Makinouchi, Takeshi; Danhara, Toru; Isoda, Kunitoshi.

1983-01-01

Fission-track ages of volcanic ash layers within the Tokai Group and associate formations in the east coast areas of Ise Bay are obtained by grain-by-grain method with which individual ages for the respective zircon grains are measured. They are as follows; 1) a volcanic ash layer in the Karayama Formation (tentative age: 1.9 +- 0.4 Ma). Among the zircon grains in this layer, essential ones occupy only 1 per cent, and the others are accidental. 2) Ohtani volcanic ash layer (4.3 +- 0.6 Ma). 3) Kosugaya volcanic ash layer (4.0 +- 0.5 Ma). 4) Kaminoma volcanic ash layer (5.3 +- 0.4 Ma). 5) A volcanic ash layer in the Toyoura Formation seems to be older than 10 Ma. 6) Zircon grains in the Kofu volcanic ash layer (Tokai Group) include two types of spontaneous namely track, clear and vague ones. The latter vague tracks are shorter and thiner, and seem to suffer thermal annealing. The ages obtained have clarified the following Points; a) The tentative age, 1.9 Ma, of the ''Karayama'' volcanic ash layer suggests the existence of unknown Plio-Pleistocene sediment in the Nagoya area. b) The sedimentary basin of Lake Tokai was formed in the latest Miocene, about 6.5 Ma. Generation of the basin coincides approximately with the stage of synchronous and abrupt change in sedimentation rate in sedimentary basins on the Pacific side of central and southern Japan. c) The Tokai Group in Chita (Tokoname Group) intercalates the Gilbert/Epoch 5 boundary in the paleomagnetic chronology in the middle horizon of the group. d) Average rate of sedimentation is about 1 m/10 4 yrs in the marginal areas of the basin, and 3-5 m/10 4 yrs in the central areas. (author)

Angular momenta of fission fragments in the {alpha}-accompanied fission of {sup 252}Cf

Energy Technology Data Exchange (ETDEWEB)

Jandel, M.; Kliman, J.; Krupa, L.; Morhac, M. [Slovak Academy of Sciences, Department of Nuclear Physics, Bratislava (Slovakia); Joint Institute for Nuclear Research, Flerov Laboratory for Nuclear Reactions, Dubna (Russian Federation); Hamilton, J.H.; Kormicki, J.; Ramayya, A.V.; Hwang, J.K.; Luo, Y.X.; Fong, D.; Gore, P. [Vanderbilt University, Department of Physics, Nashville, TN (United States); Ter-Akopian, G.M.; Oganessian, Yu.Ts.; Rodin, A.M.; Fomichev, A.S.; Popeko, G.S. [Joint Institute for Nuclear Research, Flerov Laboratory for Nuclear Reactions, Dubna (Russian Federation); Daniel, A.V. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Rasmussen, J.O.; Macchiavelli, A.O.; Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Donangelo, R.; Cole, J.D.

2005-06-01

For the first time, average angular momenta of the ternary fission fragments {sup 100,102}Zr, {sup 106}Mo, {sup 144,146}Ba and {sup 138,140,142}Xe from the {alpha}-accompanied fission of {sup 252}Cf were obtained from relative intensities of prompt {gamma}-ray transitions with the use of the statistical model calculation. Average values of the angular momenta were compared with the corresponding values for the same fission fragments from the binary fission of {sup 252}Cf. Results indicate the presence of a decreasing trend in the average values of angular momenta induced in ternary fission fragments compared to the same binary fission fragments. On the average, the total angular momentum extracted for ternary fission fragments is {proportional_to}1.4{Dirac_h} lower than in binary fission. Consequently, results indicate that the mechanism of the ternary {alpha}-particles emission may directly effect an induction of angular momenta of fission fragments, and possible scenarios of such mechanisms are discussed. Further, the dependence of the angular momenta of {sup 106}Mo and {sup 140}Xe on the number of emitted neutrons from correlated pairs of primary fragments was obtained also showing a decreasing dependence of average angular momenta with increasing number of emitted neutrons. Consequences are briefly discussed. (orig.)

Growth of fine holes in polyethylenenaphthalate film irradiated by fission fragments

International Nuclear Information System (INIS)

Komaki, Y.; Tsujimura, S.

1976-01-01

Growth of fine holes by chemical etching in polyethylenenaphthalate films exposed to fission fragments were examined by measuring gas flow through the films. The etching rate along tracks, the radial etching rate, and the bulk etching rate were determined at effective hole diameters of 100 to 1000 A and hole densities of approximately 10 8 cm -2 . The effects of ethanol and surfactants on the etching rates were studied from the viewpoint of attaining less-tapered holes

Theories of fission gas behaviour

Energy Technology Data Exchange (ETDEWEB)

Dias, J W.C. [Companhia Brasileira de Tecnologia Nuclear, Rio de Janeiro (Brazil). Diretoria de Tecnologia e Desenvolvimento; Merckx, K R

1976-01-01

A review is presented of the theoretical developments and experimental evidence that have helped to evolve current models used to describe the behavior of inert fission gases created during the irradiation of reactor fuel materials. The phenomena which are stressed relate primarily to steady state behavior of fuel elements but are also relevant to an understanding of transient behavior. The processes considered include gas atom solubility; gas atom diffusivity; bubble nucleation; and bubble growth by bubble coalescence.

Goodness of isospin in neutron rich systems from the fission fragment distribution

Science.gov (United States)

Garg, Swati; Jain, Ashok Kumar

2017-09-01

We present the results of our calculations for the relative yields of neutron-rich fission fragments emitted in 208Pb (18O, fission) reaction by using the concept of the conservation of isospin and compare with the experimental data. We take into account a range of isospin values allowed by the isospin algebra and assume that the fission fragments are formed in isobaric analog states. We also take into account the neutron multiplicity data for various neutron-emission channels in each partition, and use them to obtain the weight factors in calculating the yields. We then calculate the relative yields of the fission fragments. Our calculated results are able to reproduce the experimental trends reasonably well. This is the first direct evidence of the isospin conservation in neutron-rich systems and may prove a very useful tool in their studies.

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.

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

International Nuclear Information System (INIS)

Akkouche, M.

2007-05-01

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

Neutron-induced fission cross sections

International Nuclear Information System (INIS)

Weigmann, H.

1991-01-01

In the history of fission research, neutron-induced fission has always played the most important role. The practical importance of neutron-induced fission rests upon the fact that additional neutrons are produced in the fission process, and thus a chain reaction becomes possible. The practical applications of neutron-induced fission will not be discussed in this chapter, but only the physical properties of one of its characteristics, namely (n,f) cross sections. The most important early summaries on the subject are the monograph edited by Michaudon which also deals with the practical applications, the earlier review article on fission by Michaudon, and the review by Bjornholm and Lynn, in which neutron-induced fission receives major attention. This chapter will attempt to go an intermediate way between the very detailed theoretical treatment in the latter review and the cited monograph which emphasizes the applied aspects and the techniques of fission cross-section measurements. The more recent investigations in the field will be included. Section II will survey the properties of cross sections for neutron-induced fission and also address some special aspects of the experimental methods applied in their measurement. Section Ill will deal with the formal theory of neutron-induced nuclear reactions for the resolved resonance region and the region of statistical nuclear reactions. In Section IV, the fission width, or fission transmission coefficient, will be discussed in detail. Section V will deal with the broader structures due to incompletely damped vibrational resonances, and in particular will address the special case of thorium and neighboring isotopes. Finally, Section VI will briefly discuss parity violation effects in neutron-induced fission. 74 refs., 14 figs., 3 tabs

Uranium analysis in water flowing by the nuclear track detection method on solid dielectric materials

International Nuclear Information System (INIS)

Arambula, H.

1981-01-01

The objective of this experiment was threefold: to study the content of uranium in tap and spring water, to establish a technique for the quantitative analysis for the presence of uranium in liquids, and to test the qualities as detector fission fragments of three solid insulator materials using the nuclear tracks register method. The latter allows for the measurement of concentrations of fissile elements up to 10 -12 gr/gm employing (n, f.f.) reactions. The test samples were of tap water and of water from six fresh water springs located in San Luis Potosi and Guanajuato. Glass, lexan polycarbonate and muscovite mica were the detector materials used. The technique consisted in evaporating the water from the test samples, which had been previously placed upon the detector materials, and in doing the same for the standard control sample solutions having known concentrations of uranium. All the samples were then irradiated with thermal neutrons, and the 235 U, present in the samples, fissioned. The fission fragments produced permanent damage on the detectors, known as latent tracks. A specific corroding chemical was then applied to each detector which caused the latent tracks to dissolve into grooves. Known as etching tracks, these grooves were microscopically visible and could be measured for track density (tracks/mm 2 ). The concentrations of uranium present in the test samples were measured by comparing the track densities of the test samples with those of the standard control samples. The concentration of uranium found in the spring water samples ranged from 0.09 to 0.89 μqr.U/1, and those of tap water, from 0.18 to 0.19 μqr U/1. Lexan polycarbonate and muscovite mica proved to be better, as detectors, than glass. Glass for quantitative analysis, we found not recommendable as a detector material because of its alterable composition in the presence of uranium. (author)

Correlation of errors in the Monte Carlo fission source and the fission matrix fundamental-mode eigenvector

International Nuclear Information System (INIS)

Dufek, Jan; Holst, Gustaf

2016-01-01

Highlights: • Errors in the fission matrix eigenvector and fission source are correlated. • The error correlations depend on coarseness of the spatial mesh. • The error correlations are negligible when the mesh is very fine. - Abstract: Previous studies raised a question about the level of a possible correlation of errors in the cumulative Monte Carlo fission source and the fundamental-mode eigenvector of the fission matrix. A number of new methods tally the fission matrix during the actual Monte Carlo criticality calculation, and use its fundamental-mode eigenvector for various tasks. The methods assume the fission matrix eigenvector is a better representation of the fission source distribution than the actual Monte Carlo fission source, although the fission matrix and its eigenvectors do contain statistical and other errors. A recent study showed that the eigenvector could be used for an unbiased estimation of errors in the cumulative fission source if the errors in the eigenvector and the cumulative fission source were not correlated. Here we present new numerical study results that answer the question about the level of the possible error correlation. The results may be of importance to all methods that use the fission matrix. New numerical tests show that the error correlation is present at a level which strongly depends on properties of the spatial mesh used for tallying the fission matrix. The error correlation is relatively strong when the mesh is coarse, while the correlation weakens as the mesh gets finer. We suggest that the coarseness of the mesh is measured in terms of the value of the largest element in the tallied fission matrix as that way accounts for the mesh as well as system properties. In our test simulations, we observe only negligible error correlations when the value of the largest element in the fission matrix is about 0.1. Relatively strong error correlations appear when the value of the largest element in the fission matrix raises

The Growth of Sea cucumber Stichopus herrmanni After Transverse Induced Fission in Two and Three Fission Plane

Directory of Open Access Journals (Sweden)

Retno Hartati

2016-06-01

Full Text Available Transverse induced fission proven could be done in Teripang Tril, Stichopus herrmanni. This present works aimed to analyze wound recovery, regeneration period and growth of Teripang Trill  after asexual reproduction by fission using two and three fission plane. Observations were made every day until the sea cucumber body separated into two or more (depending on treatment and reared for 16 weeks.  The results showed that there are differences in wound recovery, regeneration period and growth of S. herrmanni depend on their different fission plane. The wound recovery and regeneration period (days of anterior, middle and posterior individu S. herrmanni resulted from two and three fission plane were varied but the two fission plane the anterior individu recover for longer period than posterior part and  the wound recover process in both end for thee fission plane was same. Average growth of anterior and posterior fragment were longer for two fission plane than three fission plane.  The middle fragment (M1 and M2 both fission plane was able to grow but very low.  It showed that three fission plane gave very slow growth in every fragment of the body. Keywords: growth, post-fission, fission plane, Stichopus herrmanni

Effect of fission dynamics on the spectra and multiplicities of prompt fission neutrons

International Nuclear Information System (INIS)

Nix, J.R.; Madland, D.G.; Sierk, A.J.

1985-01-01

With the goal of examining their effect on the spectra and multiplicities of the prompt neutrons emitted in fission, we discuss recent advances in a unified macroscopic-microscopic description of large-amplitude collective nuclear dynamics. The conversion of collective energy into single-particle excitation energy is calculated for a new surface-plus-window dissipation mechanism. By solving the Hamilton equations of motion for initial conditions appropriate to fission, we obtain the average fission-fragment translational kinetic energy and excitation energy. The spectra and multiplicities of the emitted neutrons, which depend critically upon the average excitation energy, are then calculated on the basis of standard nuclear evaporation theory, taking into account the average motion of the fission fragments, the distribution of fission-fragment residual nuclear temperature, the energy dependence of the cross section for the inverse process of compound-nucleus formation, and the possibility of multiple-chance fission. Some illustrative comparisons of our calculations with experimental data are shown

Equilibrium fission model calculations

International Nuclear Information System (INIS)

Beckerman, M.; Blann, M.

1976-01-01

In order to aid in understanding the systematics of heavy ion fission and fission-like reactions in terms of the target-projectile system, bombarding energy and angular momentum, fission widths are calculated using an angular momentum dependent extension of the Bohr-Wheeler theory and particle emission widths using angular momentum coupling

Fusion-fission type collisions

International Nuclear Information System (INIS)

Oeschler, H.

1980-01-01

Three examples of fusion-fission type collisions on medium-mass nuclei are investigated whether the fragment properties are consistent with fission from equilibrated compound nuclei. Only in a very narrow band of angular momenta the data fulfill the necessary criteria for this process. Continuous evolutions of this mechnism into fusion fission and into a deep-inelastic process and particle emission prior to fusion have been observed. Based on the widths of the fragment-mass distributions of a great variety of data, a further criterion for the compound-nucleus-fission process is tentatively proposed. (orig.)

Fission neutron multiplicity calculations

International Nuclear Information System (INIS)

Maerten, H.; Ruben, A.; Seeliger, D.

1991-01-01

A model for calculating neutron multiplicities in nuclear fission is presented. It is based on the solution of the energy partition problem as function of mass asymmetry within a phenomenological approach including temperature-dependent microscopic energies. Nuclear structure effects on fragment de-excitation, which influence neutron multiplicities, are discussed. Temperature effects on microscopic energy play an important role in induced fission reactions. Calculated results are presented for various fission reactions induced by neutrons. Data cover the incident energy range 0-20 MeV, i.e. multiple chance fission is considered. (author). 28 refs, 13 figs

Fission yield measurements at IGISOL

Science.gov (United States)

Lantz, M.; Al-Adili, A.; Gorelov, D.; Jokinen, A.; Kolhinen, V. S.; Mattera, A.; Moore, I.; Penttilä, H.; Pomp, S.; Prokofiev, A. V.; Rakopoulos, V.; Rinta-Antila, S.; Simutkin, V.; Solders, A.

2016-06-01

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.

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.

Signatures of Coulomb fission: a theoretical study

International Nuclear Information System (INIS)

Oberacker, V.; Kruse, H.; Pinkston, W.T.; Greiner, W.

1979-01-01

Evidence for Coulomb fission (CF) is noted first. Then the Hamiltonian is set down and explained, and an expression for the CF probability of CF is obtained. Results are summarized. Figures show the CF probability of 238 U as a function of projectile charge number and the excitation functions for CF of 238 U by 184 W and 136 Xe. 3 figures

Study of hypernuclei fission

International Nuclear Information System (INIS)

Malek, F.

1990-01-01

This work is about PS177 experience made on LEAR machine at CERN in 1988. The annihilation reaction of anti protons on a target of Bismuth or Uranium is studied. Lambda particles are produced by this reaction, in the nucleus in 2% of cases 7.1 10 -3 hypernuclei by stopped antiproton in the target are produced. The prompt hypernucleus fission probability of uranium is 75% and that of Bismuth 10%. The mass distribution of fission fragments is symmetrical ((≡ the excitation energy of the nucleus is very high). If the nucleus hasn't fissioned, the non-mesonic lambda decay, gives it an energy of 100 MeV, what allows to fission later. This fission is delayed because the hypernucleus lifetime is 1.3 +0.25 -0.21 10 -10 sec for Bismuth [fr

Irradiation effects in fused quartz 'Suprasil' as a detector of fission fragments under high flux of reactor neutrons

International Nuclear Information System (INIS)

Moraes, O.M.G. de.

1984-01-01

A systematic study about the registration characteristics of synthetic fused quartz 'Suprasil I' use as a detector of fission fragments under high flux of reactor neutrons and the effects of irradiation on it was performed. Fission fragments of 252 Cf, gamma radiation doses of of 60 Co up to 150 MGy, and integrated neutrons fluxes up to 10 20 n/cm 2 were used. A model to explain the effects on track registration and development characteristics of 'Suprasil I' irradiated on reactors were proposed, based on the obtained results for efficiency an for annealing. (C.G.C.) [pt

Elastocapillary Instability in Mitochondrial Fission

Science.gov (United States)

Gonzalez-Rodriguez, David; Sart, Sébastien; Babataheri, Avin; Tareste, David; Barakat, Abdul I.; Clanet, Christophe; Husson, Julien

2015-08-01

Mitochondria are dynamic cell organelles that constantly undergo fission and fusion events. These dynamical processes, which tightly regulate mitochondrial morphology, are essential for cell physiology. Here we propose an elastocapillary mechanical instability as a mechanism for mitochondrial fission. We experimentally induce mitochondrial fission by rupturing the cell's plasma membrane. We present a stability analysis that successfully explains the observed fission wavelength and the role of mitochondrial morphology in the occurrence of fission events. Our results show that the laws of fluid mechanics can describe mitochondrial morphology and dynamics.

Determination of uranium content in dental porcelains by means of the fission track method and estimation of radiation dose to oral mucosa by radioactive elements

International Nuclear Information System (INIS)

Sairenji, Eiko; Moriwaki, Kazunari; Shimizu, Masami; Noguchi, Kunikazu; Anzai, Ikuro.

1979-01-01

Porcelain teeth, some of which contained uranium compounds for aesthetic purpose, have been widely used in dental clinics. Recently, the hazardous effects by uranium radiation were suggested. In the present study, the authors carried out the determination of uranium concentrations of four major brands of porcelain teeth marketed in Japan using the fission track method, and the absorbed doses of oral tissues were calculated by the authors' introduced formula for calculation of alpha radiation. Average uranium concentrations of the brands studied were determined 3.6 ppm (0.33 - 10 ppm, Japan), 18 ppm (0.69 - 81 ppm, Japan), 9.4 ppm (2.5 - 14 ppm, Japan) and 82 ppm (11 - 205 ppm, U.S.A.), respectively. The corresponding dose equivalents at the surface of oral mucosal membrane were 2.9 rem y -1 , 14 rem y -1 , 7.6 rem y -1 and 66 rem y -1 . (author)

Determination of the fission products yields, lanthanide and yttrium, in the fission of 238U with neutrons of fission spectra

International Nuclear Information System (INIS)

Nicoli, I.G.

1981-06-01

A radiochemical investigation is performed to measure the cumulative fission product yields of several lantanides and yttrium nuclides in the 238 U by fission neutron spectra. Natural and depleted uranium are irradiated under the same experimental conditions in order to find a way to subtract the contribution of the 235 U fission. 235 U percentage in the natural uranium was 3.5 times higher than in the depleted uranium. Uranium oxides samples are irradiated inside the core of the Argonaut Reactor, at the Instituto de Engenharia Nuclear, and the lantanides and yttrium are chemically separated. The fission products gamma activities were detected, counted and analysed in a system constituted by a high resolution Ge(Li) detector, 4096 multichannel analyser and a PDP-11 computer. Cumulative yields for fission products with half-lives between 1 to 33 hours are measured: 93 Y, 141 La, 142 La, 143 Ce and 149 Nd. The chain total yields are calculated. The cumulative fission yields measured for 93 Y, 141 La, 142 La, 143 Ce and 149 Nd are 4,49%, 4,54%, 4,95%, 4,16% and 1,37% respectively and they are in good agreement with the values found in the literature. (Author) [pt

Barium 139 as Fission Indicator

Energy Technology Data Exchange (ETDEWEB)

Broda, E.

1943-07-01

This report is based on a measurement performed at the Cavendish Laboratory (Cambridge) by E. Broda in December 1943 where a technique has been worked out for measuring the fission density in a uranium containing medium in relative units by determining the amount of a suitable fission product formed. Generally a given fission product will be formed in natural uranium by slow neutron fission of U235 or by fast neutron fission of either U235 or U238. It is intended to translate the relative units into absolute units by comparison of the Ba yield with the indication of UF6 fission chamber in the same medium. This has to be done separately for fast and slow neutron fission as the yields may be different. Another application of the technique developed is the measurement of thermal neutron density in an uraniferous medium without using a detector subject to variations of sensitivity according to the properties of the medium. (nowak)

Radiationless decay, fission and fusion of excitons in irradiated molecular crystals

International Nuclear Information System (INIS)

Klein, Gerard.

1977-01-01

The creation and evolution of excited states in ionizing particle tracks were investigated. The passage of high energy ionizing particles in molecular crystals results in the formation of highly excited states which energy is generally above the molecular ionization potential. The theory of non radiative transitions, which describes the transitions from the highly excited states to the lowest singlet and triplet excitons S 1 and T 1 is developed. Among these non radiative transitions, the fission of singlet excitons into two singlet or triplet excitons of lower energies is studied experimentally. These results and a kinematics study of the S 1 and T 1 excitons in ionizing particle tracks were used to get a complete description of the scintillation. These results are in good agreement with the experimental measurements on the scintillation [fr

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...

Fission fragment distributions within dynamical approach

Energy Technology Data Exchange (ETDEWEB)

Mazurek, K. [Institute of Nuclear, Physics Polish Academy of Sciences, Krakow (Poland); Nadtochy, P.N. [Omsk State Technical University, Omsk (Russian Federation); Ryabov, E.G.; Adeev, G.D. [Omsk State University, Physics Department, Omsk (Russian Federation)

2017-04-15

The review covers recent developments and achievements in the dynamical description of fission process at high excitation energy. It is shown that the dynamical approach based on multidimensional Langevin equations combined with the statistical description of nuclear decay by particles evaporation is capable of fairly well describing the formation of fission fragment mass-energy, charge, and angular distributions of fission fragments in coincidence with the pre- and post-scission particle emission. The final yields of fission and evaporation residues channels products could be obtained. The detailed description of fission dynamics allows studying different stages of fission process, indicating the most important ingredients governing fission process and studying in detail such fundamental nuclear properties as nuclear viscosity and fission timescale. The tasks and perspectives of multidimensional dynamical approach are also discussed. (orig.)

New isomeric states in 152,154,156Nd produced by spontaneous fission of 252Cf

International Nuclear Information System (INIS)

Gautherin, C.; Houry, M.; Korten, W.; Le Coz, Y.; Lucas, R.; Phan, X.H.; Theisen, C.; Belier, G.; Girod, M.; Meot, V.; Peru, S.; Astier, A.; Ducroux, L.; Meyer, M.; Redon, N.

1998-01-01

Isomeric states have been observed in fission-fragments produced by spontaneous fission of 252 Cf. These states are found in neutron rich nuclei of different structure and deformations. About 50 isomeric nuclei have been observed using coincidences between γ-rays identified in EUROGAM II and fission fragments detected in photovoltaic cells (SAPhIR). Lifetimes in the range from 20 ns to 2μs have been measured. Presented calculations based on HFB+D1S force on new measured isomeric states in the 152,154,156 Nd show evidence for K-isomers. (orig.)

Tip model of cold fission

International Nuclear Information System (INIS)

Goennenwein, F.; Boersig, B.

1991-01-01

Cold fission is defined to be the limiting case of nuclear fission where virtually all of the available energy is converted into the total kinetic energy of the fragments. The fragments have, therefore, to be born in or at least close to their respective ground states. Starting from the viewpoint that cold fission corresponds to most compact scission configurations, energy constraints have been exploited to calculate minimum tip distances between the two nascent fragments in binary fission. Crucial input parameters to this tip model of cold fission are the ground-state deformations of fragment nuclei. It is shown that the minimum tip distances being compatible with energy conservation vary strongly with both the mass and charge fragmentation of the fission prone nucleus. The tip distances refer to nuclei with equivalent sharp surfaces. In keeping with the size of the surface width of leptodermous nuclei, only configurations where the tip distances are smaller than a few fm may be considered as valid scission configurations. From a comparison with experimental data on cold fission this critical tip distance appears to be 3.0 fm for the model parameters chosen. Whenever the model calculation yields tip distances being smaller than the critical value, a necessary condition for attaining cold fission is considered to be fulfilled. It is shown that this criterion allows to understand in fair agreement with experiment which mass fragmentations are susceptible to lead to cold fission and which fragment-charge divisions are the most favored in each isobaric mass chain. Being based merely on energy arguments, the model cannot aim at predicting fragment yields in cold fission. However, the tip model proposed appears well suited to delineate the phase space where cold fission phenomena may come into sight. (orig.)

Asymmetric fission of 47V induced by the 23Na+24Mg reaction

International Nuclear Information System (INIS)

Beck, C.; Djerroud, B.; Haas, F.; Freeman, R.M.; Hachem, A.; Heusch, B.; Morsad, A.; Vuillet-A-Cilles, M.; Sanders, S.J.

1993-01-01

The properties of fully energy-damped processes (deep-inelastic orbiting, fusion-evaporation, and fusion-fission processes) have been investigated in the nearly mass-symmetric entrance-channel 23 Na + 24 Mg reaction leading to the 47 V compound nucleus. By comparison with previous data for the mass-asymmetric 35 Cl + 12 C reaction forming the same compound system at the same excitation energy, no entrance-channel effects are observed in either the evaporation residue or the fusion-fission yields. This is in contrast to the situation with the 28 Si + 12 C and 24 Mg + 16 O reactions where an orbiting process is evident. The asymmetrical elemental distributions of the fusion-fission fragments of the massA=47 system are well described by a transition-state model that accounts for the spin and mass-asymmetry dependence of the fission saddle point

A review of selected aspects of the effect of water vapor on fission gas release from uranium oxycarbide

International Nuclear Information System (INIS)

Myers, B.F.

1994-04-01

A selective review is presented of previous measurements and the analysis of experiments on the effect of water vapor on fission gas release from uranium oxycarbide. Evidence for the time-dependent composition of the uranium oxycarbide fuel; the diffusional release of fission gas; and the initial, rapid and limited release of stored fission gas is discussed. In regard to the initial, rapid release of fission gas, clear restrictions on mechanistic hypotheses can be deduced from the experimental data. However, more fundamental experiments may be required to establish the mechanism of the rapid release

A threshold for dissipative fission

International Nuclear Information System (INIS)

Thoennessen, M.; Bertsch, G.F.

1993-01-01

The empirical domain of validity of statistical theory is examined as applied to fission data on pre-fission data on pre-fission neutron, charged particle, and γ-ray multiplicities. Systematics are found of the threshold excitation energy for the appearance of nonstatistical fission. From the data on systems with not too high fissility, the relevant phenomenological parameter is the ratio of the threshold temperature T thresh to the (temperature-dependent) fission barrier height E Bar (T). The statistical model reproduces the data for T thresh /E Bar (T) thresh /E Bar (T) independent of mass and fissility of the systems

Cooling, exhumation, and deformation in the Hindu Kush, NW Pakistan: New constraints from preliminary 40Ar/39Ar and fission track analyses

Science.gov (United States)

Faisal, Shah; Larson, Kyle P.; Camacho, Alfredo; Coutand, Isabelle

2018-06-01

Asian crust in the Hindu Kush region in northern Pakistan records a protracted history of rifting, subduction and collision not commonly preserved within the Himalaya. Because of this, it is key to understanding the development of the southern Eurasian margin both prior to and after collision with India. New mica 40Ar/39Ar and apatite fission track geochronologic data from this region provide constraints on the kinematics of the Hindu Kush. 40Ar/39Ar muscovite and biotite ages from the late Cambrian Kafiristan pluton are 379.7 ± 1.7 Ma and 47.2 ± 0.3 Ma, respectively. The muscovite age may record cooling or partial resetting, while the biotite age is interpreted to record a thermal disruption associated with the early stages of continental collision in the Himalayan system. A 111.0 ± 0.6 Ma muscovite age from the northern part of the Tirich Mir pluton (∼123 Ma old; U-Pb) is interpreted to indicate a recrystallization event ∼12 Myrs after its intrusion. In addition, a younger muscovite age of 47.5 ± 0.2 Ma was derived from the opposite side of the same pluton in the immediate hanging wall of the Tirich Mir fault. This Eocene age is interpreted to represent the time of recrystallization during fault (re)activation in the early stages of India-Asia continent-continent collision. 40Ar/39Ar biotite analysis from the Buni-Zom pluton yields an age of 61.6 ± 1.1 Ma and is interpreted to reflect cooling at mid-upper crustal levels subsequent to the pluton's emplacement in the middle Cretaceous. Finally, 17.1-21.3 Ma 40Ar/39Ar ages from the Garam Chasma pluton and surrounding metapelites indicate cooling immediately following crystallization of the leucogranite body in the earliest Miocene/latest Oligocene. The younger cooling history is resolved by fission track dating of apatite (AFT). In the vicinity of the bounding Tirich Mir fault, the Tirich Mir pluton yields an AFT age of 1.4 ± 0.3 Ma, which is consistent with active exhumation associated with the surface

Insights into nuclear structure and the fission process from spontaneous fission

Energy Technology Data Exchange (ETDEWEB)

Hamilton, J.H.; Butler-Moore, K.; Ramayya, A.V. [Vanderbilt Univ., Nashville, TN (United States)] [and others

1993-12-31

The {gamma}-rays emitted following spontaneous and induced fission are rich sources of information about the structure of neutron-rich nuclei and about the fission process itself. The study of spontaneous fissioning isotopes with large Ge detector arrays are providing a wealth of such information as seen, for example, in recent reports. In this paper we present some of our most recent results on nuclear structure studies and conclusions on the fission process itself. In our work, we have employed in spontaneous fission, a triple gamma coincidence study for the first time and a high resolution, X-ray detector-{gamma}-coincidence study. These data provide powerful ways of separating the gamma rays which belong to a particular nucleus. The triple coincidence technique was used to uniquely identify the levels in {sup 136}Te and higher spin states in its N=84 isotones, {sup 138}Xe and {sup 140}Ba{sup 171}. Some other examples of the level structures observed in the low and high mass partners are presented, including a detailed analysis of the backbending of the moment of inertia in {sup 112,114,116}Pd. Finally, we present the first examples of how our analysis allows one to extract a detailed picture of the dependence of the angular momentum on the mass and atomic numbers of the fission fragments and of the long-sought neutron multiplicity distribution from zero-n to ten-n as a function of the charge and mass asymmetry.

Dual-fission chamber and neutron beam characterization for fission product yield measurements using monoenergetic neutrons

Science.gov (United States)

Bhatia, C.; Fallin, B.; Gooden, M. E.; Howell, C. R.; Kelley, J. H.; Tornow, W.; 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.; Becker, J. A.; Macri, R.; Ryan, C.; Sheets, S. A.; Stoyer, M. A.; Tonchev, A. P.

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.

Preparation of Track Etch Membrane Filters Using Polystyrene Film

International Nuclear Information System (INIS)

Kaewsaenee, Jerawut; Ratanatongchai, Wichian; Supaphol, Pitt; Visal-athaphand, Pinpan

2007-08-01

Full text: Polystyrene nuclear track etch membrane filters was prepared by exposed 13 .m thin film polystyrene with fission fragment. Nuclear latent track was enlarged to through hole on the film by etching with 80 o C 40% H 2 SO 4 with K 2 Cr 2 O 7 solution for 6-10 hour. The hole size was depend on concentration of etching solution and etching time with 1.3-3.4 .m hole diameter. The flow rate test of water was 0.79-1.56 mm cm-2 min-1 at 109.8-113.7 kPa pressure

Reexamination of fission fragment angular distributions and the fission process: Formalism

International Nuclear Information System (INIS)

Bond, P.D.

1985-01-01

The theory of fission fragment angular distributions is examined and the universally used expression is found to be valid only under restrictive assumptions. A more general angular distribution formula is derived and applied to recent data of high spin systems. At the same time it is shown that the strong anisotropies observed from such systems can be understood without changing the essential basis of standard fission theory. The effects of reaction mechanisms other than complete fusion on fission fragment angular distributions are discussed and possible angular distribution signatures of noncompound nucleus formation are mentioned

Process for treating fission waste

International Nuclear Information System (INIS)

Rohrmann, C.A.; Wick, O.J.

1983-01-01

A method is described for the treatment of fission waste. A glass forming agent, a metal oxide, and a reducing agent are mixed with the fission waste and the mixture is heated. After melting, the mixture separates into a glass phase and a metal phase. The glass phase may be used to safely store the fission waste, while the metal phase contains noble metals recovered from the fission waste

Investigation of the heavy nuclei fission with anomalously high values of the fission fragments total kinetic energy

Science.gov (United States)

Khryachkov, Vitaly; Goverdovskii, Andrei; Ketlerov, Vladimir; Mitrofanov, Vecheslav; Sergachev, Alexei

2018-03-01

Binary fission of 232Th and 238U induced by fast neutrons were under intent investigation in the IPPE during recent years. These measurements were performed with a twin ionization chamber with Frisch grids. Signals from the detector were digitized for further processing with a specially developed software. It results in information of kinetic energies, masses, directions and Bragg curves of registered fission fragments. Total statistics of a few million fission events were collected during each experiment. It was discovered that for several combinations of fission fragment masses their total kinetic energy was very close to total free energy of the fissioning system. The probability of such fission events for the fast neutron induced fission was found to be much higher than for spontaneous fission of 252Cf and thermal neutron induced fission of 235U. For experiments with 238U target the energy of incident neutrons were 5 MeV and 6.5 MeV. Close analysis of dependence of fission fragment distribution on compound nucleus excitation energy gave us some explanation of the phenomenon. It could be a process in highly excited compound nucleus which leads the fissioning system from the scission point into the fusion valley with high probability.

Interactive and automated systems for nuclear track measurements with applications to fast neutron dosimetry

International Nuclear Information System (INIS)

Roberts, J.H.; Gold, R.; McNeece, J.P.; Preston, C.C.; Ruddy, F.H.

1983-12-01

Interactive and automatic track measuring systems have been developed primarily for fast neutron dosimetry in and around reactors. The interactive system is used for proton recoil measurements in nuclear research emulsions and the automatic systems for counting fission fragment tracks in Muscovite mica. The status of these systems, along with illustrative applications, are presented, particularly with regard to their relationship to neutron personnel dosimetry. 16 references, 12 figures

Fifty years with nuclear fission

International Nuclear Information System (INIS)

Behrens, J.W.; Carlson, A.D.

1989-01-01

The news of the discovery of nuclear fission, by Otto Hahn and Fritz Strassmann in Germany, was brought to the United States by Niels Bohr in January 1939. Since its discovery, the United States, and the world for that matter, has never been the same. It therefore seemed appropriate to acknowledge the fifieth anniversary of its discovery by holding a topical meeting entitled, ''Fifty Years with Nuclear Fission,'' in the United States during the year 1989. The objective of the meeting was to bring together pioneers of the nuclear industry and other scientists and engineers to report on reminiscences of the past and on the more recent development in fission science and technology. The conference highlighted the early pioneers of the nuclear industry by dedicated a full day (April 26), consisting of two plenary sessions, at the National Academy of Sciences (NAS) in Washington, DC. More recent developments in fission science and technology in addition to historical reflections were topics for two fully days of sessions (April 27 and 28) at the main site of the NIST in Gaithersburg, Maryland. The wide range of topics covered in this Volume 1 by this topical meeting included plenary invited, and contributed sessions entitled: Preclude to the First Chain Reaction -- 1932 to 1942; Early Fission Research -- Nuclear Structure and Spontaneous Fission; 50 Years of Fission, Science, and Technology; Nuclear Reactors, Secure Energy for the Future; Reactors 1; Fission Science 1; Safeguards and Space Applications; Fission Data; Nuclear Fission -- Its Various Aspects; Theory and Experiments in Support of Theory; Reactors and Safeguards; and General Research, Instrumentation, and By-Product. The individual papers have been cataloged separately

Study of α-particle multiplicity in 16O+196Pt fusion-fission reaction

International Nuclear Information System (INIS)

Kapoor, K.; Kumar, A.; Bansal, N.

2016-01-01

Study of dynamics of fusion-fission reaction is one of the interesting parts of heavy-ion-induced nuclear reaction. Extraction of fission time scales using different probes is of central importance for understanding the dynamics of fusion-fission process. In the past, extensive theoretical and experimental efforts have been made to understand the various aspects of the heavy ion induced fusion-fission reactions. Compelling evidences have been obtained from the earlier studies that the fission decay of hot nuclei is protracted process i.e. slowed down relative to the expectations of the standard statistical model, and large dynamical delays are required due to this hindrance. Nuclear dissipation is assumed to be responsible for this delay and more light particles are expected to be emitted during the fission process. One of neutron multiplicity measurements have been performed for the 16,18 O+ 194,198 Pt populating the CN 210,212,214,216 Rn and observed fission delay due to nuclear viscosity. In order to have complete understanding for the dynamics of 212 Rn nucleus, we measured the charged particle multiplicity for 16 O+ 196 Pt system. Study of charged particles will give us more information about the emitter in comparison to neutrons as charged particles faces Coulomb barrier and are more sensitive probe for understanding the dynamics of fusion-fission reactions. In the present work, we are reporting some of the preliminary results of charged particle multiplicity

A Preliminary Study on Time Projection Chamber Simulation for Fission Cross Section Measurements with Geant4

International Nuclear Information System (INIS)

Kim, Jong Woon; Lee, Youngouk; Kim, Jae Cheon

2014-01-01

We present the details of the TPC simulation with Geant4 and show the results. TPC can provide more information than a fission chamber in that it is possible to distinguish different particle types. Simulations are conducted for uranium and plutonium targets with 20MeV neutrons. The simulation results are compared with the reference and show reasonable results. This is the first phase of study for realizing a TPC in the NFS at RAON, and we have more work to do, such as applying an electric field, signal processing in the simulation, and manufacturing of a TPC. The standard in fission cross section measurement is a fission chamber. It is basically just two parallel plates separated by a few centimeters of gas. A power supply connected to the plates sets up a moderate electric field. The target is deposited onto one of the plates. When fission occurs, the fragments ionize the gas, and the electric field causes the produced electrons to drift to the opposite plate, which records the total energy deposited in the chamber. A Time Projection Chamber (TPC) is a gas ionization detector similar to a fission chamber. However, it can measure the charged particle trajectories in the active volume in three dimensions by adding several readouts on the pad plane (fission chamber has only one readout one a pad plane). The specific ionization for each particle track enables the TPC to distinguish different particle types. A TPC will be used for fission cross section measurements in the Neutron Science Facility (NSF) at RAON. As a preliminary study, we present details of TPC simulation with Geant4 and discuss the results

Muon-induced fission

International Nuclear Information System (INIS)

Polikanov, S.

1980-01-01

A review of recent experimental results on negative-muon-induced fission, both of 238 U and 232 Th, is given. Some conclusions drawn by the author are concerned with muonic atoms of fission fragments and muonic atoms of the shape isomer of 238 U. (author)

Modeling fission gas release in high burnup ThO2-UO2 fuel

International Nuclear Information System (INIS)

Long, Y.; Yuan, Y.; Pilat, E.E.; Rim, C.S.; Kazimi, M.S.

2001-01-01

A preliminary fission gas release model to predict the performance of thoria fuel using the FRAPCON-3 computer code package has been formulated. The following modeling changes have been made in the code: - Radial power/burnup distribution; - Thermal conductivity and thermal expansion; - Rim porosity and fuel density; - Diffusion coefficient of fission gas in ThO 2 -UO 2 fuel and low temperature fission gas release model. Due to its lower epithermal resonance absorption, thoria fuel experiences a much flatter distribution of radial fissile products and radial power distribution during operation as compared to uranian fuel. The rim effect and its consequences in thoria fuel, therefore, are expected to occur only at relatively high burnup levels. The enhanced conductivity is evident for ThO 2 , but for a mixture the thermal conductivity enhancement is small. The lower thermal fuel expansion tends to negate these small advantages. With the modifications above, the new version of FRAPCON-3 matched the measured fission gas release data reasonably well using the ANS 5.4 fission gas release model. (authors)

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

Energy production using fission fragment rockets

International Nuclear Information System (INIS)

Chapline, G.; Matsuda, Y.

1991-08-01

Fission fragment rockets are nuclear reactors with a core consisting of thin fibers in a vacuum, and which use magnetic fields to extract the fission fragments from the reactor core. As an alternative to ordinary nuclear reactors, fission fragment rockets would have the following advantages: Approximately twice as efficient if one can directly convert the fission fragment energy into electricity; by reducing the buildup of a fission fragment inventory in the reactor one could avoid a Chernobyl type disaster; and collecting the fission fragments outside the reactor could simplify the waste disposal problem. 6 refs., 4 figs., 2 tabs

Optimization of the recoil-shadow projection method for the investigation of short-lived fission isomers

Energy Technology Data Exchange (ETDEWEB)

Helmecke, M.; Thirolf, P.G.; Habs, D.; Gartzke, E.; Kolhinen, V.; Lang, C.; Szerypo, J.; Trepl, L. [Fakultaet f. Physik, LMU Muenchen (Germany); Maier-Leibnitz Laboratory, Garching (Germany)

2009-07-01

Spectroscopic studies of super- and hyperdeformed actinide nuclei offer the possibility to gain insight into the multiple-humped fission barrier landscape. With the identification of deep third minima in {sup 234}U and {sup 236}U the systematics of fission isomers in light actinides was revisited, especially searching for isomers in light uranium isotopes with half-lives in the pico-second range. Using the recoil-shadow projection method and solid state nuclear track detectors, an experimental search for their observation has been started. This well-established detection technique nowadays benefits from an efficient analysis technology based on a PC-controlled auto-focus microscope and a CCD camera together with pattern recognition software. The flatness and the definition of the shadow edge of the target is the critical point of this method: Due to the energy loss of the beam the target carrier foil (1{mu}m Ni) may develop thermal distortions in the {mu}m range, leading to misinterpretations of isomeric fission fragments. Therefore the flatness of the target foil is continuously monitored via a capacitance measurement. First results applying this method to the search of a fission isomer in {sup 234}U via the {sup 232}Th({alpha},2n) reaction are presented.

Fission dynamics of hot nuclei

Indian Academy of Sciences (India)

2014-04-05

Apr 5, 2014 ... across the fission barrier is very small or in other words, the fission barrier is much ... of this shape evolution, the gross features of the fissioning nucleus can be described ..... [7] Y Abe, C Gregoire and H Delagrange, J. Phys.

Study on fission blanket fuel cycling of a fusion-fission hybrid energy generation system

International Nuclear Information System (INIS)

Zhou, Z.; Yang, Y.; Xu, H.

2011-01-01

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.

Physics and chemistry of fission

International Nuclear Information System (INIS)

1979-01-01

Full text: In the pleasant and hospitable atmosphere of the Kernforschungsanlage Juelich in the Federal Republic of Germany, the IAEA symposium on the Physics and Chemistry of Fission took place. Almost 200 scientists attended, 154 abstracts were submitted, and 57 papers presented, but more important than the numbers was the quality of the contributions and the progress reported at the symposium. The neutron was discovered almost 50 years ago; 40 years ago the idea of nuclear fission was born. Since then, a number of laboratories have worked hard to explain the phenomenon of fission One would expect that by now scientists would know exactly what happens in a nucleus before and during the process of fission, particularly as there are hundreds of power and research reactors in operation, and fission of uranium isotopes is the basis of their functioning. At first glance, fission seems a simple process: a neutron hits and penetrates the uranium nucleus which becomes excited, i.e. has a surplus of energy. One way to get rid of this energy is for the nucleus to split into two parts; additional products of this process are energy and more neutrons. Nature, however, seems to dislike such straightforward explanations. In the case of fission, scientists have observed a number of phenomena which disagree with a simple model. Sometimes, a nucleus will split into two parts without being 'attacked' by a neutron; this spontaneous fission opens up a new line of fission research and several contributions at the symposium reported on sophisticated experiments designed to unravel some of its specific details. Sometimes, a fissioning nucleus will emit another particle: ternary fission has become a powerful tool for studying the properties of nuclei during the fission process. For the scientist, it is fascinating to observe how the nucleus behaves during fission. They invent models which are supposed to reproduce the most probable course of events leading to fission. In one of these

Theoretical Description of the Fission Process

International Nuclear Information System (INIS)

Nazarewicz, Witold

2009-01-01

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

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.)

Resolution of the nature of the coupling in subthreshold fission in 238U+n

International Nuclear Information System (INIS)

Auchampaugh, G.F.; de Saussure, G.; Olsen, D.K.; Ingle, R.W.; Perez, R.B.; Macklin, R.L.

1986-01-01

The analysis of a recent high-resolution neutron capture measurement at 152 m has provided the first evidence that the strong fission resonance at 721 eV is a class-II resonance. This conclusion is based on the measured capture width of 4.7 +- 0.6 MeV, which is considerably smaller than the average capture width of 23.5 MeV for the neighboring resonances. Furthermore, after analyzing the fission widths for the 721- and 1211-eV clusters, we conclude for the J/sup π/ = 1/2 + fission barrier in 239 U that the inner barrier is lower than the outer barrier by approx.1.5 MeV

Dynamic of fission and quasi-fission revealed by pre-scission neutron evaporation

International Nuclear Information System (INIS)

Hinde, D.J.

1991-06-01

The dependence of pre-scission neutron multiplicities (ν-pre) on the mass-split and total kinetic energy (TKE) in fusion-fission and quasi-fission has been measured for a wide range of projectile-target combinations. the data indicate that the fusion-fission time scale is shorter for asymmetric splits than for symmetric splits, whilst there is no dependence on TKE. For quasi-fission reactions induced using 64 Ni projectiles, ν-pre falls rapidly with increasing TKE, indicating that these neutrons are emitted near to or after scission. A new interpretation of both neutron multiplicities and mean energies (the neutron clock-thermometer) allows the extraction of time scales with much less uncertainty than previously, and also gives information about the deformation from which the neutrons are emitted. 15 refs., 13 figs

Measurements of fission cross-sections and of neutron production rates; Mesures de sections efficaces de fission et du nombre de neutrons prompts emis par fission

Energy Technology Data Exchange (ETDEWEB)

Billaud, P; Clair, C; Gaudin, M; Genin, R; Joly, R; Leroy, J L; Michaudon, A; Ouvry, J; Signarbieux, C; Vendryes, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

a) Measurements of neutron induced fission cross-sections in the low energy region. The variation of the fission cross sections of several fissile isotopes has been measured and analysed, for neutron energies below 0,025 eV. The monochromator was a crystal spectrometer used in conjunction with a mechanical velocity selector removing higher order Bragg reflections. The fissile material was laid down on the plates of a fission chamber by painting technic. An ionization chamber, having its plates coated with thin {sup 10}B layers, was used as the neutron flux monitor. b) Measurement of the fission cross section of {sup 235}U. We intend to measure the variation of the neutron induced fission cross section of {sup 235}U over the neutron energy range from 1 keV by the time of flight method. The neutron source is the uranium target of a pulsed 28 MeV electron linear accelerator. The detector is a large fission chamber, with parallel plates, containing about 10 g of {sup 235}U (20 deposits of 25 cm diameter). The relative fission data were corrected for the neutron spectrum measured with a set of BF{sub 3} proportional counters. c) Mean number {nu} of neutrons emitted in neutron induced fission. We measured the value of {nu} for several fissile isotopes in the case of fission induced by 14 MeV neutrons. The 14 MeV neutrons were produced by D (t, n) {alpha} reaction by means of a 300 kV Cockcroft Walton generator. (author)Fren. [French] a) Mesures de sectionficaces de fission a basse energie. Nous avons mesure et analyse la variation de la section efficace de fission de divers isotopes fissiles pour des neutrons d'energie inferieure a 0,025 eV. Le monochromateur est constitue par un spectrometre a cristal auquel est associe un selecteur mecanique destine a eliminer les diffractions de Bragg d'ordre superieur au premier. Le materiau fissile est contenu dans une chambre a fission sous forme de depots realises par peinture; une chambre d'ionisation a depots minces de B{sub 10

Theory of nuclear fission: a review

International Nuclear Information System (INIS)

Mosel, U.

1976-01-01

General properties of nuclear fission are reviewed and related to our present knowledge of fission theory. For this purpose the basic reasons for the shape of the fission barriers are discussed and their consequences compared with experimental results on barrier shapes and structures. Special emphasis is put on the asymmetry of the fission barriers and mass-distributions and its relation to the shells of the nascent fragment shells. Finally the problem of calculating fission cross sections is discussed

Registration of alpha particles in Makrofol-E nuclear track detectors

Energy Technology Data Exchange (ETDEWEB)

Rammah, Y.S. [Physics Department, Faculty of Science, Menoufia University, Shebin El-Koom (Egypt); Abdalla, Ayman M., E-mail: aymanabdalla62@hotmail.com [Physics Department, Faculty of Sciences and Arts, Najran University, P. O. Box. 11001, Najran (Saudi Arabia); Promising Centre for Sensors and Electronic Devices, Faculty of Arts and Sciences, Najran University (Saudi Arabia); Ashraf, O., E-mail: osama.ashraf@edu.asu.edu.eg [Physics Department, Faculty of Education, Ain Shams University, Cairo 11575 (Egypt); Ashry, A.H. [Physics Department, Faculty of Education, Ain Shams University, Cairo 11575 (Egypt)

2016-06-15

Highlights: • Makrofol-E detectors have been irradiated with alpha particles and fission fragments. • Fast detection of alpha particles in Makrofol-E detectors. • Bulk etching rate was calculated from fission track diameters. - Abstract: Fast detection of alpha particles in the range from 1 to 5 MeV in Makrofol-E polycarbonate nuclear track detectors (PCTDs) using a new chemical etchant was investigated. {sup 252}Cf and {sup 241}Am-thin open sources were used for irradiating Makrofol-E detectors with fission fragments and alpha particles in air at normal pressure and temperature (NPT). A chain of experimental work has been carried out using new etchants to register alpha particle in short time in Makrofol-E polycarbonate detectors. The etching efficiency were exhibited a clear dependence on the amount of methanol in the etching solution and etching time. The optimized chemical condition obtained at this stage of development for 200 μm Makrofol-E detectors are (8 ml of 10 N NaOH + 2 ml CH{sub 3}OH) etching solutions at 60 °C for 3 h. In this study; it is possible to observe energy detection windows for Makrofol-E detectors according to applied etching duration. Makrofol-E introduced the characteristic Bragg peak, which indicates the advantages of this detector as alpha spectrometer. Consequently, the suggested new etchant can be developed for heavy ions detection and monitoring radon levels and its daughters.

Neutron rich clusters and the dynamics of fission and fusion

International Nuclear Information System (INIS)

Armbruster, P.

1988-07-01

In this lecture I want to discuss experimental evidence for the appearance of cluster aspects in the dynamics of large rearrangement processes, as fusion and fission. Clusters in the sense as used in my lecture are the strongly bound doubly magic nuclei as 20 Ca 28 48 , 28 Ni 50 78 , 132 50 Sn 82 , and 208 82 Pb 126 and the superheavy nucleus 298 114 184 . Two of these nuclei, 78 Ni and 298 114 have not yet been identified. I discuss first the experimental findings from heavy element production. Then I cover the stability of cluster aspects to intrinsic excitation energy in fusion and fission. (orig./HSI)

Nuclear track radiography of 'hot' aerosol particles

Energy Technology Data Exchange (ETDEWEB)

Boulyga, S.F.; Kievitskaja, A.I.; Kievets, M.K.; Lomonosova, E.M.; Zhuk, I.V.; Yaroshevich, O.I.; Perelygin, V.P.; Petrova, R.; Brandt, R.; Vater, P

1999-06-01

Nuclear track radiography was applied to identify aerosol 'hot' particles which contain elements of nuclear fuel and fallout after Chernobyl NPP accident. For the determination of the content of transuranium elements in radioactive aerosols the measurement of the {alpha}-activity of 'hot' particles by SSNTD was used in this work, as well as radiography of fission fragments formed as a result of the reactions (n,f) and ({gamma},f) in the irradiation of aerosol filters by thermal neutrons and high energy gamma quanta. The technique allowed the sizes and alpha-activity of 'hot' particles to be determined without extracting them from the filter, as well as the determination of the uranium content and its enrichment by {sup 235}U, {sup 239}Pu and {sup 241}Pu isotopes. Sensitivity of determination of alpha activity by fission method is 5x10{sup -6} Bq per particle. The software for the system of image analysis was created. It ensured the identification of track clusters on an optical image of the SSNTD surface obtained through a video camera and the determination of size and activity of 'hot' particles00.

Solid state nuclear track detection: a useful geological/geophysical tool

International Nuclear Information System (INIS)

Khan, H.A.; Qureshi, A.A.

1994-01-01

Solid State Nuclear Track Detection (SSNTD) is a relatively new nuclear particle detection technique. Since its inception, it has found useful application in almost every branch of science. This paper gives a very brief review of the role it has played in solving some geological/geophysical problems. Since the technique has been found useful in a wide spectrum of geological/geophysical applications, it was simply not possible to discuss all of these in this paper due to severe space restrictions. However, an attempt has been made to discuss the salient features of some of the most prominent applications in the geological and geophysical sciences. The paper has been divided into two parts. Firstly, applications based on radon measurements by SSNTDs have been described. These include: Uranium/thorium and mineral exploration, search for geothermal energy sources, study of volcanic processes, location of geological faults and earthquake prediction, for example. Secondly, applications based on the study of spontaneous fission tracks in geological samples have been described briefly. The second group of applications includes: fission track dating (FTD) of geological samples, FTD in the study of emplacement times, provenance studies, and thermal histories of minerals. Necessary references have been provided for detailed studies of (a) the applications cited in this paper, and (b) other important geological/geophysical applications, which unfortunately could not be covered in the present paper. (author)