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Sample records for accumulation fluence monitor

  1. Accuracy of helium accumulation fluence monitor for fast reactor dosimetry

    Ito, Chikara; Aoyama, Takafumi [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1998-03-01

    A helium (He) accumulation fluence monitor (HAFM) has been developed for fast reactor dosimetry. In order to evaluate the measurement accuracy of neutron fluence by the HAFM method, the HAFMs of enriched boron (B) and beryllium (Be) were irradiated in the Fast Neutron Source Reactor `YAYOI`. The number of He atoms produced in the HAFMs were measured and compared with the calculated values. As a result of this study, it was confirmed that the neutron fluence could be measured within 5 % by the HAFM method, and that met the required accuracy for fast reactor dosimetry. (author)

  2. Calibration of a He accumulation fluence monitor for fast reactor dosimetry

    Ito, Chikara [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1997-03-01

    The helium accumulation fluence monitor (HAFM) has been developed for a fast reactor dosimetry. The HAFM measurement system was calibrated using He gas and He implanted samples and the measurement accuracy was confirmed to be less than 5%. Based on the preliminary irradiation test in JOYO, the measured He in the {sup 10}B type HAFM agreed well with the calculated values using the JENDL-3.2 library. (author)

  3. Standard Test Method for Application and Analysis of Helium Accumulation Fluence Monitors for Reactor Vessel Surveillance, E706 (IIIC)

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This test method describes the concept and use of helium accumulation for neutron fluence dosimetry for reactor vessel surveillance. Although this test method is directed toward applications in vessel surveillance, the concepts and techniques are equally applicable to the general field of neutron dosimetry. The various applications of this test method for reactor vessel surveillance are as follows: 1.1.1 Helium accumulation fluence monitor (HAFM) capsules, 1.1.2 Unencapsulated, or cadmium or gadolinium covered, radiometric monitors (RM) and HAFM wires for helium analysis, 1.1.3 Charpy test block samples for helium accumulation, and 1.1.4 Reactor vessel (RV) wall samples for helium accumulation. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  4. Fluence

    Harker, Alexander

    2011-01-01

    Thoughts crystallise, become atmosphere. Ambiences contract, seize up, splinter. Everything within; the eye sees in all directions. Garrett Sholdice & Benedict Schlepper-Connolly Clarinet on Fluence: Jonathan Sage Electric guitars and source recordings on Fractures: Alexander Harker Sound engineering, production and mastering: Alexander Harker Executive Producers: Garrett Sholdice & Benedict Schlepper-Connolly Design: Benedict Schlepper-Connolly Fluence was commissio...

  5. Review of the Palisades pressure vessel accumulated fluence estimate and of the least squares methodology employed

    This report provides a review of the Palisades submittal to the Nuclear Regulatory Commission requesting endorsement of their accumulated neutron fluence estimates based on a least squares adjustment methodology. This review highlights some minor issues in the applied methodology and provides some recommendations for future work. The overall conclusion is that the Palisades fluence estimation methodology provides a reasonable approach to a open-quotes best estimateclose quotes of the accumulated pressure vessel neutron fluence and is consistent with the state-of-the-art analysis as detailed in community consensus ASTM standards

  6. Review of the Palisades pressure vessel accumulated fluence estimate and of the least squares methodology employed

    Griffin, P.J.

    1998-05-01

    This report provides a review of the Palisades submittal to the Nuclear Regulatory Commission requesting endorsement of their accumulated neutron fluence estimates based on a least squares adjustment methodology. This review highlights some minor issues in the applied methodology and provides some recommendations for future work. The overall conclusion is that the Palisades fluence estimation methodology provides a reasonable approach to a {open_quotes}best estimate{close_quotes} of the accumulated pressure vessel neutron fluence and is consistent with the state-of-the-art analysis as detailed in community consensus ASTM standards.

  7. The development report of an intelligent neutron fluence integration monitor

    An intelligent neutron fluence integration monitor is introduced. It is used to measure the received neutron fluence of the monocrystalline silicon in reactor radiation channel. The significance of study and specifications of the instrument are briefly described. The emphasis is on the working principle, structure and characteristics of the instrument is intelligent due to use of monolithic microcomputer. It has many advantages proved in the actual practice, such as powerful function, high accuracy, diversity of application, high level automatization, easy to operate, high reliability, etc. After using this instrument the monocrystalline silicon radiation technology is improved and the efficiency of production is raised. (1 fig.)

  8. The vessel fluence; Fluence cuve

    NONE

    2001-07-01

    This book presents the proceedings of the technical meeting on the reactors vessels fluence. They are grouped in eight sessions: the industrial context and the stakes of the vessels control; the organization and the methodology for the fluence computation; the concerned physical properties; the reference computation methods; the fluence monitoring in an industrial context; vessels monitoring under irradiation; others methods in the world; the research and development programs. (A.L.B.)

  9. Development and applications of energy-specific fluence monitor for field monitoring

    A portable energy-specific fluence monitor is developed for field monitoring as well as to serve as stand-alone data acquisition system to measure dose rate due to routine releases at various locations in and around Nuclear Power Reactors. The data from an array of such monitors deployed over a region of interest would help in evolving a methodology to arrive at the source term evaluation in the event of a postulated nuclear incident. The other method that exists for this purpose is by conducting tracer experiments using known release of a gas like SF6 into the atmosphere and monitoring their concentrations downwind. The above instrument enables one to use the routine release of 41Ar as a tracer gas. The Argon fluence monitor houses a CsI(Tl) detector and associated miniature electronics modules for conditioning the signal from the detector. Data logging and in-situ archival of the data are controlled by a powerful web enabled communication controller preloaded with Microsoft Windows Compact Edition (WIN CE). The application software is developed in Visual Basic.NET under Compact Framework and deployed in the module. The paper gives an outline of the design aspects of the instrument, associated electronics and calibration of the instrument, including the preliminary results obtained using the instrument. The utility of the system is established by carrying out field survey around Madras Atomic Power Station (MAPS), consisting of two Pressurized Heavy Water Reactors (PHWR), by mapping the 41Ar plume. Additional features such as enhancing the monitor capability with embedded GPS along with real-time linking using wireless networking techniques are also being incorporated.

  10. Correction of Ra(α, n)Be neutron source fluence in long-time experiments due to accumulation of polonium 210

    Consideration is being given to distinctive features of the process of variation of the neutron fluence of the Ra(α, n)Be ampouled neutron sources as a function of 210Po accumulation describing the variation of the fluence is derived. It is shown that using this source as a reference in the experiment lasting for 5 years, the uncertainty in the value of the neutron fluence calculated from the formula proposed is estimated at no more than 0.1%. 15 refs.; 2 tabs

  11. Fast reactor fluence dosimetry. Technical progress report, October 1978-March 1979

    Information is presented concerning the development and performance testing of helium accumulation fluence monitors and the measurement of helium distribution in irradiated unfueled Type 316 stainless steel fuel cans

  12. Real-time verification of multileaf collimator-driven radiotherapy using a novel optical attenuation-based fluence monitor

    Purpose: Multileaf collimator (MLC)-driven conformal radiotherapy modalities [e.g., such as intensity-modulated radiotherapy (IMRT), intensity-modulated arc therapy, and stereotactic body radiotherapy] are more subject to delivery errors and dose calculation inaccuracies than standard modalities. Fluence monitoring during treatment delivery could reduce such errors by allowing an independent interface to quantify and assess measured difference between the delivered and planned treatment administration. We developed an optical attenuation-based detector to monitor fluence for the on-line quality control of radiotherapy delivery. The purpose of the current study was to develop the theoretical background of the invention and to evaluate the detector's performance both statistically and in clinical situations. Methods: We aligned 60 27-cm scintillating fibers coupled to a photodetector via clear optical fibers in the direction of motion of each of the 60 leaf pairs of a 120 leaves Millenium MLC on a Varian Clinac iX. We developed a theoretical model to predict the intensity of light collected on each side of the scintillating fibers when placed under radiation fields of varying sizes, intensities, and positions. The model showed that both the central position of the radiation field on the fiber (xc) and the integral fluence passing through the fiber (Φint) could be assessed independently in a single measurement. We evaluated the performance of the prototype by (1) measuring the intrinsic variation of the measured values of xc and Φint, (2) measuring the impact on the measured values of xc and Φint of random leaf positioning errors introduced into IMRT fields, and (3) comparing the predicted values of xc and Φint calculated with the treatment planning software to the measured values of xc and Φint in order to assess the predictive effectiveness of the developed theoretical model. Results: We observed a very low intrinsic dispersion, dominated by Poisson statistics

  13. A novel wide range, real-time neutron fluence monitor based on commercial off the shelf gallium arsenide light emitting diodes

    Displacement damage produced by high-energy neutrons in gallium arsenide (GaAs) light emitting diodes (LED) results in the reduction of light output. Based on this principle we have developed a simple, cost effective, neutron detector using commercial off the shelf (COTS) GaAs-LED for the assessment of neutron fluence and KERMA at critical locations in the vicinity of the 230 MeV proton therapy cyclotron operated by Westdeutsches Protonentherapiezentrum Essen (WPE). The LED detector response (mV) was found to be linear within the neutron fluence range of 3.0x108-1.0x1011 neutron cm-2. The response of the LED detector was proportional to neutron induced displacement damage in LED; hence, by using the differential KERMA coefficient of neutrons in GaAs, we have rescaled the calibration curve for two mono-energetic sources, i.e. 1 MeV neutrons and 14 MeV neutrons generated by D+T fusion reaction. In this paper we present the principle of the real-time GaAs-LED based neutron fluence monitor as mentioned above. The device was calibrated using fast neutrons produced by bombarding a thick beryllium target with 14 MeV deuterons from a TCC CV 28 medical cyclotron of the Strahlenklinik University Hospital Essen.

  14. Monitoring water accumulation in a glacier using magnetic resonance imaging

    A. Legchenko

    2013-05-01

    Full Text Available Tête Rousse is a small polythermal glacier located in the Mont Blanc area (French Alps at an altitude of 3100 to 3300 m. Recent accumulation of melt water in the glacier was assumed to occur, but such accumulation had yet to be confirmed. Using Surface Nuclear Magnetic Resonance imaging (3-D-SNMR, we showed that the temperate part of the Tête Rousse glacier contains two separate water-filled caverns (central and upper caverns. In 2009, the central cavern contained about 55 000 m3 of water. Since 2010, the cavern is drained every year. Using 3-D-SNMR, we monitored the changes caused by this pumping in the water distribution within the glacier body. Twice a year, we carried out magnetic resonance imaging of the entire glacier and estimated the volume of water accumulated in the central cavern. Our results show the changes in cavern geometry and recharge rate: in two years, the central cavern lost about 73% of its initial volume, but 65% were lost in one year after the first pumping. We also observed that, after being drained, the cavern was recharged at an average rate of 20 to 25 m3 d−1 over the winter months and 120 to 180 m3 d−1 in summer. These observations illustrate how ice and water may refill englacial volume being emptied by artificial draining. Comparison of the 3-D-SNMR results with those obtained by drilling and pumping showed a very good correspondence, confirming the high reliability of 3-D-SNMR imaging.

  15. Monitoring Damage Accumulation in Ceramic Matrix Composites Using Electrical Resistivity

    Smith, Craig E.; Morscher, Gregory N.; Xia, Zhenhai H.

    2008-01-01

    The electric resistance of woven SiC fiber reinforced SiC matrix composites were measured under tensile loading conditions. The results show that the electrical resistance is closely related to damage and that real-time information about the damage state can be obtained through monitoring of the resistance. Such self-sensing capability provides the possibility of on-board/in-situ damage detection and accurate life prediction for high-temperature ceramic matrix composites. Woven silicon carbide fiber-reinforced silicon carbide (SiC/SiC) ceramic matrix composites (CMC) possess unique properties such as high thermal conductivity, excellent creep resistance, improved toughness, and good environmental stability (oxidation resistance), making them particularly suitable for hot structure applications. In specific, CMCs could be applied to hot section components of gas turbines [1], aerojet engines [2], thermal protection systems [3], and hot control surfaces [4]. The benefits of implementing these materials include reduced cooling air requirements, lower weight, simpler component design, longer service life, and higher thrust [5]. It has been identified in NASA High Speed Research (HSR) program that the SiC/SiC CMC has the most promise for high temperature, high oxidation applications [6]. One of the critical issues in the successful application of CMCs is on-board or insitu assessment of the damage state and an accurate prediction of the remaining service life of a particular component. This is of great concern, since most CMC components envisioned for aerospace applications will be exposed to harsh environments and play a key role in the vehicle s safety. On-line health monitoring can enable prediction of remaining life; thus resulting in improved safety and reliability of structural components. Monitoring can also allow for appropriate corrections to be made in real time, therefore leading to the prevention of catastrophic failures. Most conventional nondestructive

  16. Monitoring of the aquatic environment by species accumulator of pollutants: a review

    Oscar RAVERA

    2001-09-01

    Full Text Available This paper is a short review on the biomonitoring of aquatic environments by animal and plant species accumulators of toxic pollutants ("scavengers". This monitoring is based on the relationship between the pollutant concentration in the organism and that in its environment, and not on alterations produced by pollution on the biota. The latter is the basis of other types of biomonitoring, such as those based on the biotic and diversity indices and saprobic scale. The various aspects of monitoring by pollutant accumulators are illustrated; for example, the uptake and loss of pollutants, the "critical organs" and "tissues", the detoxification mechanisms and the most common factors (C.F., BAF, BSAF for establishing a connection between the pollutant concentration in the organism and that in its environment. Several examples of this monitoring on heavy metals, radioisotopes and organic micropollutants are reported. The advantages of this monitoring, the characteristics of the species to be used as bioaccumulators and some practical suggestions are listed. A close collaboration between the scientific teams working on the biomonitoring based on accumulator organisms and on the chemical monitoring is recommended from the scientific and economic point of view.

  17. Neutron detector simultaneously measures fluence and dose equivalent

    Dvorak, R. F.; Dyer, N. C.

    1967-01-01

    Neutron detector acts as both an area monitoring instrument and a criticality dosimeter by simultaneously measuring dose equivalent and fluence. The fluence is determined by activation of six foils one inch below the surface of the moderator. Dose equivalent is determined from activation of three interlocked foils at the center of the moderator.

  18. Neutron fluence measurements

    For research reactor work dealing with such subjects as radiation effects on solids and such disciplines as radiochemistry and radiobiology, the radiation dose or neutron fluence is an essential parameter in evaluating results. Unfortunately it is very difficult to determine. Even when the measurements have been accurate, it is difficult to compare results obtained in different experiments because present methods do not always reflect the dependence of spectra or of different types of radiation on the induced processes. After considering the recommendations of three IAEA Panels, on 'In-pile dosimetry' held in July 1964, on 'Neutron fluence measurements' in October 1965, and on 'In-pile dosimetry' in November 1966, the Agency established a Working Group on Reactor Radiation Measurements. This group consisted of eleven experts from ten different Member States and two staff members of the Agency. In the measurement of energy absorbed by materials from neutrons and gamma rays, there are various reports and reviews scattered throughout the literature. The group, however, considered that the time was ripe for all relevant information to be evaluated and gathered together in the form of a practical guide, with the aim of promoting consistency in the measurement and reporting of reactor radiation. The group arranged for the material to be divided into two manuals, which are expected to be useful both for experienced workers and for beginners

  19. The clinical significance of ultrasound monitoring acute fluid accumulation inacute pancreatitis

    Yan Luo; Chao Xin Yuan; Jun Ming Jiang; Lin Dai; Yu Lan Peng; Yong Zhong Li

    2000-01-01

    AIM To evaluate the usefulness of ultrasound monitoring acute fluid accumulation in acute pancreatitis.METHODS Six hunclred and twenty-seven patients with acute pancreatitis were undergone ultrasonographicexamination. All examinations were performed by the attending doctors. The first scans were performed onthe first or second day after admission to our hospital, if there were acute fluid accumulation inperipancreatic spaces including the lesser sac, pararenalspaces, peritoneal cavity, or even thoracic cavity,then the follow-up scans were routinely performed 3 - 7 days following the initial scan and this interval wasdependent upon the severity of acute pancreatitis, and partieulanly noticed the changes of pancreas and thefluid mentioned above. Continuous variables were analyzed by t test, Discrete variables were analyzed by the,x2 test and rank sum test using SPSS, P<0.05 was considered significant.RESULTS Acute fluid accumulation was fouad in 57.5% of 627 patients among them 14.4% evolved intocomplications and 85.6% resolved spontaneously. The most frequent sites of fluid accumulation are theperitoneal cavity and the left hemithorax, followed by the lesser sac and right hemithorax (x2 = 738,P<0.0001); the hospital stay was longer as the quantity of acute fluid accumulation increased (P<0.0001, t = 2.2 - 4.2 ). There was no fluid accumulation in mild AP and more than 2 sites in severe AP (P<0.0001, x2 = 147.8).CONCLUSION The number of sites as well as the duration of fluid accumulation are proportional tohospital stay and the severity of AP.

  20. Fluorescence resonance energy transfer sensors for quantitative monitoring of pentose and disaccharide accumulation in bacteria

    Looger Loren L

    2008-06-01

    Full Text Available Abstract Background Engineering microorganisms to improve metabolite flux requires detailed knowledge of the concentrations and flux rates of metabolites and metabolic intermediates in vivo. Fluorescence resonance energy transfer sensors represent a promising technology for measuring metabolite levels and corresponding rate changes in live cells. These sensors have been applied successfully in mammalian and plant cells but potentially could also be used to monitor steady-state levels of metabolites in microorganisms using fluorimetric assays. Sensors for hexose and pentose carbohydrates could help in the development of fermentative microorganisms, for example, for biofuels applications. Arabinose is one of the carbohydrates to be monitored during biofuels production from lignocellulose, while maltose is an important degradation product of starch that is relevant for starch-derived biofuels production. Results An Escherichia coli expression vector compatible with phage λ recombination technology was constructed to facilitate sensor construction and was used to generate a novel fluorescence resonance energy transfer sensor for arabinose. In parallel, a strategy for improving the sensor signal was applied to construct an improved maltose sensor. Both sensors were expressed in the cytosol of E. coli and sugar accumulation was monitored using a simple fluorimetric assay of E. coli cultures in microtiter plates. In the case of both nanosensors, the addition of the respective ligand led to concentration-dependent fluorescence resonance energy transfer responses allowing quantitative analysis of the intracellular sugar levels at given extracellular supply levels as well as accumulation rates. Conclusion The nanosensor destination vector combined with the optimization strategy for sensor responses should help to accelerate the development of metabolite sensors. The new carbohydrate fluorescence resonance energy transfer sensors can be used for in vivo

  1. Monitoring of streams: macrozoobenthos and accumulation of heavy metals and radionuclides in bottom sediments

    To evaluate the environmental quality of streams in integrated monitoring sites (IMS) and agrostations (AS), the macrozoobenthos communities and accumulation of heavy metals and radionuclides in bottom sediments were studied during 1993-1996. Samples of macrozoobenthos were collected in stream biotopes which were recommended for monitoring. Community biodiversity was assessed by Shannon-Wiener and Simpson indices, and water quality of streams was estimated by Trent and Mean Chandler biotic indices. Heavy metal (Pb, Cd, Cu, Cr, Ni, Mn) concentrations and radionuclide (137Cs, 134Cs, 40K, 90Sr) activity were determined in sediments. Macrozoobenthos communities indicated that the studied streams were clean waters. The heavy metal concentrations in surficial sediments showed annual and seasonal changes and differences between monitoring sites. The Cu concentration in the soft turfy stream sediments at the Aukstaitija IMS was twice as high as that in sediments of other monitoring streams with hard sandy-gravel bottoms. During 1994-1996, the Ni concentration decreased, while levels of Cu, Cd and Cr were relatively stable. The Pb concentrations decreased in all IMS, while those in AS increased. The concentration of 137 Cs was relatively stable in agrostation streams. Compared to levels in 1993, an increase of 137Cs activity was observed in sediments at the Dzuklija IMS during 1995-1996. 90Sr activity fluctuated in the monitoring sites from 1.6 to 3.7 Bq/kg dry weight. (author)

  2. Fluence complexity in IMRT fields and correlation with gamma analysis

    Our previously published method for fluence complexity calculation in IMRT fields is based on portal dose images predicted by the Portal Dose Calculation algorithm in Eclipse (version 8.6, Varian Medical Systems) in the plane of the EPID aS500 detector (Varian Medical Systems). Fluence complexity is given by the number and the amplitude of dose gradients in a field. Now the method is validated with a set of 6 patients' plans. For each patient, 4 plans with different levels of complexity have been created, using the manual smoothing tools available in Eclipse. It has been found that fluence complexity calculated with our tool is in accordance with the level of manual fluence smoothing, with the number of monitor units, the behaviour of dose-volume histogram parameters and also with the results of gamma analysis after plan verification. Our method allows to estimate fluence complexity at the planning stage and thus potentially avoid measurement of complex plans, which do not often meet the verification criteria. With the help of our method, dosimetrists could recognize non-optimally smoothed dose distributions and perform some additional smoothing prior to verification. This would save time in the process. Furthermore, too complex fluences do not improve dose distribution and can cause errors due to complicated leaf sequencing. Fluence complexity is, however, systematically different for different patients, most likely depending on the site of treatment. Hence, particular limits for acceptable fluence complexity levels have not been established yet. (authors)

  3. Damage Accumulation in Cyclically-Loaded Glass-Ceramic Matrix Composites Monitored by Acoustic Emission

    Aggelis, D. G.; Dassios, K. G.; Kordatos, E. Z.; Matikas, T. E.

    2013-01-01

    Barium osumilite (BMAS) ceramic matrix composites reinforced with SiC-Tyranno fibers are tested in a cyclic loading protocol. Broadband acoustic emission (AE) sensors are used for monitoring the occurrence of different possible damage mechanisms. Improved use of AE indices is proposed by excluding low-severity signals based on waveform parameters, rather than only threshold criteria. The application of such improvements enhances the accuracy of the indices as accumulated damage descriptors. RA-value, duration, and signal energy follow the extension cycles indicating moments of maximum or minimum strain, while the frequency content of the AE signals proves very sensitive to the pull-out mechanism. PMID:24381524

  4. Monitoring intracellular polyphosphate accumulation in enhanced biological phosphorus removal systems by quantitative image analysis.

    Mesquita, Daniela P; Amaral, A Luís; Leal, Cristiano; Carvalheira, Mónica; Cunha, Jorge R; Oehmen, Adrian; Reis, Maria A M; Ferreira, Eugénio C

    2014-01-01

    A rapid methodology for intracellular storage polyphosphate (poly-P) identification and monitoring in enhanced biological phosphorus removal (EBPR) systems is proposed based on quantitative image analysis (QIA). In EBPR systems, 4',6-diamidino-2-phenylindole (DAPI) is usually combined with fluorescence in situ hybridization to evaluate the microbial community. The proposed monitoring technique is based on a QIA procedure specifically developed for determining poly-P inclusions within a biomass suspension using solely DAPI by epifluorescence microscopy. Due to contradictory literature regarding DAPI concentrations used for poly-P detection, the present work assessed the optimal DAPI concentration for samples acquired at the end of the EBPR aerobic stage when the accumulation occurred. Digital images were then acquired and processed by means of image processing and analysis. A correlation was found between average poly-P intensity values and the analytical determination. The proposed methodology can be seen as a promising alternative procedure for quantifying intracellular poly-P accumulation in a faster and less labour-intensive way. PMID:24901627

  5. In situ X-ray monitoring of damage accumulation in SiC/RBSN tensile specimens

    Baaklini, G.Y.; Bhatt, R.T.

    1991-08-01

    The room-temperature tensile testing of silicon carbide fiber reinforced reaction-bonded silicon nitride (SiC/RBSN) composite specimens was monitored by using in-situ X-ray film radiography. Radiographic evaluation before, during, and after loading provided data on the effect of preexisting volume flaws (high density impurities, and local density variations) on the fracture behavior of composites. Results from (O)1, (O)3, (O)5, and (O)8 composite specimens showed that X-ray film radiography can monitor damage accumulations during tensile loading. Matrix cracking, fiber-matrix debonding, and fiber pullout were imaged throughout the tensile loading history of the specimens. Further, in-situ film radiography was found to be a helpful and practical technique for estimating interfacial shear strength between the SiC fiber and the RBSN matrix by the matrix crack spacing method. It is concluded that pretest, in-situ, and post-test radiography can provide for a greater understanding of ceramic matrix composite mechanical behavior, a verification of related experimental procedures, and a validation and development of related analytical models. 14 refs.

  6. The Living Filter: Monitoring Nitrate Accumulation after 50 Years of Wastewater Irrigation

    Hagedorn, J.

    2015-12-01

    As global freshwater sources decline due to environmental contamination and a growing population, more sustainable wastewater renovation techniques will need to be applied to ensure freshwater for future generations. One such example of a sustainable solution is called the Living Filter, located on the campus of Pennsylvania State University. For fifty years, Pennsylvania State University has sprayed treated wastewater onto agricultural fields and forest ecosystems, leaving natural processes to further filter the wastewater. This cyclical process is deemed sustainable because the freshwater is recycled, providing drinking water to an increasing university population and nutrients to agricultural crops, without causing major environmental catastrophes such as fish kills, eutrophication or groundwater contamination. At first glance this project seems sustainable and effective, but for how long can this setup continue without nutrient overloading and environmental contamination? To be truly declared sustainable, the hopeful answer to this question is indefinitely. Using a combination of soil core and monitoring tools, ecosystem indicators such as soil nutrient capacities, moisture levels, and soil characteristics were measured. Comparing data from the initial system installation to present data collected from soil cores showed how ecosystems changed over time. Results revealed that nitrate concentrations were elevated through the profile in all land use types, but the concentrations were below EPA threshold. Soil characteristic analysis including particle size distribution, soil elemental composition, and texture yielded inconclusive results regarding which factors control the nitrate accumulation most significantly. The nitrate depth profile findings suggest that spray irrigation at the Living Filter under the current rates of application has not caused the ultimate stage of nitrogen saturation in the spray irrigation site. Variations in land use present interesting

  7. Biologicla monitor and accumulating characteristic of moss to Pb, Fe, Cr pollution by SRXRF

    In order to explore accumulating characteristic of moss as a biological monitor to environmental pollution, cultured Physcornitrella patens of the second generation was grown for 45 days in a specially prepared nutrient medium containing different concentrations of Ph, Fe or Cr, or mixture of Fe-Pb, Fe-Cr and Fe-Cu. Elemental contents in the moss tissue were determined using SRXRF (synchrotron radiation X-ray fluorescence). Cr and K distributions in leaf and stem of the moss were obtained using micro-SRXRF. The results showed that in the sample groups of both types of the medium containing a single heavy metal or the metal mixture, the contents of polluted metal elements in the moss were correlated to the concentrations of corresponding elements in the culture medium. The moss injury was greatly aggravated with increasing content of heavy metal element. Under the contamination of heavy metals, the ability of moss to absorb nutritive elements (K, S) was declined sharply. Also due to the antagonism of excessive Cr, the content of K element deposited in moss stem decreased gradually. (authors)

  8. First Results from the Online Radiation Dose Monitoring System in ATLAS experiment

    Mandić, I; The ATLAS collaboration; Deliyergiyev, M; Gorišek, A; Kramberger, G; Mikuž, M; Franz, S; Hartert, J; Dawson, I; Miyagawa, P; Nicolas, L

    2011-01-01

    High radiation doses which will accumulate in components of ATLAS experiment during data taking will causes damage to detectors and readout electronics. It is therefore important to continuously monitor the doses to estimate the level of degradation caused by radiation. Online radiation monitoring system measures ionizing dose in SiO2 , displacement damage in silicon in terms of 1-MeV(Si) equivalent neutron fluence and fluence of thermal neutrons at several locations in ATLAS detector. In this paper design of the system, results of measurements and comparison of measured integrated doses and fluences with predictions from FLUKA simulation will be shown.

  9. Particle Test Fluence: What's the Right Number?

    LaBel, Kenneth A.

    2016-01-01

    While we have been utilizing standard fluence levels such as those listed in the JESD57 document, we have begun revisiting what an appropriate test fluence is when it comes to qualifying a device for single events. Instead of a fixed fluence level or until a specific number of events occurs, a different thought process is required.

  10. Measurement of fluence distribution of large area irradiated by scanning high energy ion beam

    In the JAERI cyclotron, the large area homogeneous irradiation by beam scanning system is used for the experiments on the research of space material, nuclear fusion material and biotechnology. The irradiation is accomplished by deflecting high energy ion beam in the horizontal and vertical directions using a pair of electromagnets. To investigate two-dimensional fluence distribution irradiated by this system, relative fluence distribution was measured with cellulose triacetate film dosimeters. The result showed that the distribution has the inhomogeneity caused by the distorted magnetic wave form of the system and the beam profile. To improve the homogeneity of the distribution, the information about the distribution must be obtained quickly. Therefore, a real time monitoring system of fluence distribution using a parallel plate avalanche counter is developed. The beam scanning system, the measurement of relative fluence distribution using a CTA dosimeter, the real time fluence distribution monitor system with a PPAC and so on are reported. (K.I.)

  11. Butyltin accumulation in the marine clam Mya arenaria: an evaluation of its suitability for monitoring butyltin pollution.

    Yang, Rui-qiang; Zhou, Qun-fang; Jiang, Gui-bin

    2006-03-01

    The use of Mya arenaria as a new sensitive biomonitor of butyltins pollution in the oceanic system was investigated. Field survey indicated that much higher levels of butyltin compounds were found in M. arenaria compared with the other species investigated. Using Mytilus edulis as a control organism, a 28 days exposure of tributyltin chloride (TBT) to M. arenaria for accumulation and subsequent 28 days breeding in clean seawater for elimination were conducted under laboratory conditions in order to confirm its high accumulation ability and characterize its kinetic behavior to TBT. Bioconcentration factor (BCF) of M. arenaria ranged from 15,538 to 91,800 after 28 days exposure. The rapid uptake and low rate to eliminate TBT of M. arenaria displayed first-order kinetics. M. arenaria shows potential as a new bioindicator to monitor TBT pollution in marine environment. PMID:16188291

  12. Toxic cyanobacterial breakthrough and accumulation in a drinking water plant: a monitoring and treatment challenge.

    Zamyadi, Arash; MacLeod, Sherri L; Fan, Yan; McQuaid, Natasha; Dorner, Sarah; Sauvé, Sébastien; Prévost, Michèle

    2012-04-01

    The detection of cyanobacteria and their associated toxins has intensified in recent years in both drinking water sources and the raw water of drinking water treatment plants (DWTPs). The objectives of this study were to: 1) estimate the breakthrough and accumulation of toxic cyanobacteria in water, scums and sludge inside a DWTP, and 2) to determine whether chlorination can be an efficient barrier to the prevention of cyanotoxin breakthrough in drinking water. In a full scale DWTP, the fate of cyanobacteria and their associated toxins was studied after the addition of coagulant and powdered activated carbon, post clarification, within the clarifier sludge bed, after filtration and final chlorination. Elevated cyanobacterial cell numbers (4.7 × 10(6)cells/mL) and total microcystins concentrations (up to 10 mg/L) accumulated in the clarifiers of the treatment plant. Breakthrough of cells and toxins in filtered water was observed. Also, a total microcystins concentration of 2.47 μg/L was measured in chlorinated drinking water. Cyanobacterial cells and toxins from environmental bloom samples were more resistant to chlorination than results obtained using laboratory cultured cells and dissolved standard toxins. PMID:22137293

  13. Development of a Secondary Neutron Fluence Standard at GELINA

    The MetroFission project, a Joint Research Project within the European Metrology Research Program, aims at addressing a number of metrological problems involved in the design of proposed Generation IV nuclear reactors. One of the objectives of this multidisciplinary project is the improvement of neutron cross section measurement techniques in order to arrive at uncertainties as required for the design and safety assessment of new generation power plants and fuel cycles. This objective is in line with the 'Uncertainty and target accuracy assessment for innovative systems using recent covariance data evaluations' published by a working party of the OECD Nuclear Energy Agency in 2008. These requests are often very challenging, being at or beyond the state-of-the-art in neutron measurements, which is set by self-normalizing methods and the neutron data standards used at laboratories where the data are measured. A secondary neutron fluence standard has been developed and calibrated at the neutron time-of-flight facility GELINA of the JRC's Institute for Reference Materials and Measurements (IRMM). It consists of a flux monitor, a reference ionization chamber containing a 10B layer and a 235U layer, and a parallel plate ionization chamber with 8 well characterized 235U deposits. These devices are used to determine the neutron fluence, based on the well-known neutron induced fission reaction on 235U. All deposits have been prepared and characterized at the IRMM target preparation lab. The secondary fluence standard at the GELINA facility can be used for reliable determination of the efficiency of fluence measurement devices used in neutron data measurements at IRMM and elsewhere. It is an essential tool to reliably calibrate fluence normalization devices used in neutron time-of-flight cross section measurements. (authors)

  14. Texture analysis on the edge-enhanced fluence of VMAT

    Textural features of edge-enhanced fluence were analysed to quantify modulation degree of volumetric modulated arc therapy (VMAT) plans. Twenty prostate and twenty head and neck VMAT plans were retrospectively selected. Fluences of VMAT plans were generated by integration of monitor units shaped by multi-leaf collimators (MLCs) at each control point. When generating fluences, the values of pixels representing MLC tips were doubled to prevent smearing out of small or irregular fields (edge-enhancement). Six kinds of textural features, including angular second moment, inverse difference moment, contrast, variance, correlation and entropy, were calculated with particular displacement distances (d) of 1, 5 and 10. Plan delivery accuracy was evaluated by gamma-index method, mechanical parameter differences between plan and delivery and differences in dose-volumetric parameters between plan and delivery. Spearman’s correlation coefficients (rs) were calculated between the values of textural features and VMAT delivery accuracy. The rs values of contrast (d = 1) with edge-enhancement to global gamma passing rates with 2%/2 mm, 1%/2 mm and 2%/1 mm were 0.546 (p < 0.001), 0.744 (p < 0.001) and 0.487 (p = 0.001), respectively. Those with local 2%/2 mm, 1%/2 mm and 2%/1 mm were 0.588, 0.640 and 0.644, respectively (all with p < 0.001). The rs values of contrast (d = 1) to MLC and gantry angle errors were -0.853 and 0.655, respectively (all with p < 0.001). The contrast (d = 1) showed statistically significant rs values in 11 dose-volumetric parameter differences from a total of 35 cases, and generally showed better correlations to plan delivery accuracy than did previously suggested textural features with non-edge-enhanced fluences, as well as conventional modulation indices. Contrast (d = 1) with edge-enhanced fluences could be used as modulation index for VMAT

  15. Seasonal ERT monitoring of subsurface processes connected to freezing, thawing, snow accumulation and melt cycles

    Krzeminska, Dominika; Starkloff, Torsten; Bloem, Esther; Stolte, Jannes

    2016-04-01

    For a better understanding of processes that influence snowmelt infiltration and runoff, and their consequences on soil erosion during spring periods, we established a long-term winter-spring ERT transect in the Gryteland catchment (Norway). The ERT transect is 71 m long, with 1 m spacing between the electrodes. It covers a depression with a north and south facing slope. The readings are collected once a week and, if needed, after a sudden change in weather conditions. Additionally, the soil transect is equipped with six TDR profiles, which register soil moisture and soil temperature every thirty minutes, at five depths (5, 10, 20, 30, 40 cm), for quantifying the ERT readings. The measurements performed during winter 2014/2015 gave promising results and showed the potential of ERT monitoring for understanding the soil thermal and hydraulic processes occurring during a winter and early spring. Moreover, there are visible differences in temporal trends and spatial variations in observed ERT patterns on the opposite facing slopes, which are of special interest. With the on-going experiment, we are aiming to understand the reoccurrence of the observed processes as well as to quantify soil moisture patterns. Herein, we would like to present the preliminary result of two ERT experiments (2014/2015 and 2015/2016) and discuss the advantages and limitations of our experiments. Moreover, we would like to stimulate the discussion about the potential of ERT for spatial and temporal monitoring of soil hydraulic and thermal processes and indirect measurements of soil water content.

  16. Development of neutron fluence measurement and evaluation technology for the test materials in the capsule

    Hong, U.; Choi, S. H.; Kang, H. D. [Kyungsan University, Kyungsan (Korea)

    2000-03-01

    The four kinds of the fluence monitor considered by self-shielding are design and fabricated for evaluation of neutron irradiation fluence. They are equipped with dosimeters consisting of Ni, Fe and Ti wires and so forth. The nuclear reaction rate is obtained by measurement on dosimeter using the spectroscopic analysis of induced {gamma}-ray. We established the nuetron fluence evaluating technology that is based on the measurement of the reaction rate considering reactor's irradiation history, burn-out, self-shielding in fluence monitor, and the influence of impurity in dosimeter. The distribution of high energy neutron flux on the vertical axis of the capsule shows fifth order polynomial equation and is good agree with theoretical value in the error range of 30% by MCNP/4A code. 22 refs., 50 figs., 27 tabs. (Author)

  17. A diaCEST MRI approach for monitoring liposomal accumulation in tumors.

    Chan, Kannie W Y; Yu, Tao; Qiao, Yuan; Liu, Qiang; Yang, Ming; Patel, Himatkumar; Liu, Guanshu; Kinzler, Kenneth W; Vogelstein, Bert; Bulte, Jeff W M; van Zijl, Peter C M; Hanes, Justin; Zhou, Shibin; McMahon, Michael T

    2014-04-28

    Nanocarrier-based chemotherapy allows preferential delivery of therapeutics to tumors and has been found to improve the efficacy of cancer treatment. However, difficulties in tracking nanocarriers and evaluating their pharmacological fates in patients have limited judicious selection of patients to those who might most benefit from nanotherapeutics. To enable the monitoring of nanocarriers in vivo, we developed MRI-traceable diamagnetic Chemical Exchange Saturation Transfer (diaCEST) liposomes. The diaCEST liposomes were based on the clinical formulation of liposomal doxorubicin (i.e. DOXIL®) and were loaded with barbituric acid (BA), a small, organic, biocompatible diaCEST contrast agent. The optimized diaCEST liposomal formulation with a BA-to-lipid ratio of 25% exhibited 30% contrast enhancement at B1=4.7μT in vitro. The contrast was stable, with ~80% of the initial CEST signal sustained over 8h in vitro. We used the diaCEST liposomes to monitor the response to tumor necrosis factor-alpha (TNF-α), an agent in clinical trials that increases vascular permeability and uptake of nanocarriers into tumors. After systemic administration of diaCEST liposomes to mice bearing CT26 tumors, we found an average diaCEST contrast at the BA frequency (5ppm) of 0.4% at B1=4.7μT while if TNF-α was co-administered the contrast increased to 1.5%. This novel approach provides a non-radioactive, non-metallic, biocompatible, semi-quantitative, and clinically translatable approach to evaluate the tumor targeting of stealth liposomes in vivo, which may enable personalized nanomedicine. PMID:24548481

  18. Natural Radioactivity Accumulated in the Arctic from Long-range Atmospheric Transport - Observations in Canadian Monitoring Stations

    Chen, Jing; Zhang, Weihua [Radiation Protection Bureau, Health Canada, 775 Brookfield Road, Ottawa K1A 1C1 (Canada)

    2014-07-01

    In the environment, the main sources of naturally occurring radionuclides come from radionuclides in the uranium decay series. Activity concentrations of uranium decay series radionuclides may vary considerably from place to place depending on the geological characteristics at the location. Their releases to the atmosphere are mainly through radon ({sup 222}Rn), a radioactive noble gas occurring naturally as an indirect decay product of uranium in soils and rocks. Due to the abundance of uranium, radon continuously emanates from continental land masses. With radon as the main source of naturally occurring radioactivity in the environment, one would think that the Arctic should be an area of low background radiation, because a considerable area of the Arctic is covered by glaciers and permafrost, and radon emanation rate has been reported to be negligible from those glacier and permafrost areas. However, available data have shown the opposite. The elevated level of naturally occurring radioactivity in the Arctic is due to natural sources outside of the Arctic, mainly through long-range atmospheric transport of radon and radon progeny. In some cases, natural radioactivity can accumulate to relatively high levels and become a health concern or a limiting factor of country food consumption. By definition, contaminants are undesirable substances which can cause harm to the environment, the biota, and humans. We can call these naturally accumulating radiological burdens to the Arctic 'natural contaminants' to distinguish them from the traditional meaning of contamination, the 'artificial contaminants' which are attributable to industrial or man-made sources. This paper reviews information available in the literature, analyses long-term atmospheric monitoring data in the Canadian high Arctic, sub-Arctic and mid-latitude sites, and provides discussion on research needed to address questions, such as how heavily the Arctic has been impacted by the

  19. Natural Radioactivity Accumulated in the Arctic from Long-range Atmospheric Transport - Observations in Canadian Monitoring Stations

    In the environment, the main sources of naturally occurring radionuclides come from radionuclides in the uranium decay series. Activity concentrations of uranium decay series radionuclides may vary considerably from place to place depending on the geological characteristics at the location. Their releases to the atmosphere are mainly through radon (222Rn), a radioactive noble gas occurring naturally as an indirect decay product of uranium in soils and rocks. Due to the abundance of uranium, radon continuously emanates from continental land masses. With radon as the main source of naturally occurring radioactivity in the environment, one would think that the Arctic should be an area of low background radiation, because a considerable area of the Arctic is covered by glaciers and permafrost, and radon emanation rate has been reported to be negligible from those glacier and permafrost areas. However, available data have shown the opposite. The elevated level of naturally occurring radioactivity in the Arctic is due to natural sources outside of the Arctic, mainly through long-range atmospheric transport of radon and radon progeny. In some cases, natural radioactivity can accumulate to relatively high levels and become a health concern or a limiting factor of country food consumption. By definition, contaminants are undesirable substances which can cause harm to the environment, the biota, and humans. We can call these naturally accumulating radiological burdens to the Arctic 'natural contaminants' to distinguish them from the traditional meaning of contamination, the 'artificial contaminants' which are attributable to industrial or man-made sources. This paper reviews information available in the literature, analyses long-term atmospheric monitoring data in the Canadian high Arctic, sub-Arctic and mid-latitude sites, and provides discussion on research needed to address questions, such as how heavily the Arctic has been impacted by the accumulation of naturally

  20. Met-myoglobin formation, accumulation, degradation, and myoglobin oxygenation monitoring based on multiwavelength attenuance measurement in porcine meat

    Nguyen, Thien; Phan, Kien Nguyen; Lee, Jee-Bum; Kim, Jae Gwan

    2016-05-01

    We propose a simple, rapid, and nondestructive method to investigate formation, accumulation, and degradation of met-myoglobin (met-Mb) and myoglobin oxygenation from the interior of porcine meat. For the experiment, color photos and attenuance spectra of porcine meat (well-bled muscle, fat, and mixed) were collected daily to perform colorimetric analysis and to obtain the differences of attenuance between 578 and 567 nm (A578-A567) and between 615 and 630 nm (A630-A615), respectively. Oxy-, deoxy-, and met-myoglobin concentration changes over storage time were also calculated using Beer-Lamberts' law with reflectance intensities at 557, 582, and 630 nm. The change of A578-A567 was well matched with the change of myoglobin oxygenation, and the change of A630-A615 corresponded well with the formation and degradation of met-Mb. In addition, attenuation differences, A578-A567 and A630-A615, were able to show the formation of met-Mb earlier than colorimetric analysis. Therefore, the attenuance differences between wavelengths can be indicators for estimating myoglobin oxygenation and met-Mb formation, accumulation, and degradation, which enable us to design a simple device to monitor myoglobin activities in porcine meat.

  1. Neutron fluence measurement in nuclear facilities

    The objective of present work is to determine the fluence of neutrons in nuclear facilities using two neutron detectors designed and built at Instituto Nacional de Investigaciones Nucleares (ININ), Mexico. The two neutron detectors are of the passive type, based on solid state nuclear tracks detectors (SSNTD). One of the two neutron detectors was used to determine the fluence distribution of the ports at the nuclear research reactor TRIGA Mark III, which belongs to ININ. In these facilities is important to know the neutron fluence distribution characteristic to carried out diverse kind of research activities. The second neutron detector was employed in order to carry out environmental neutron surveillance. The detector has the property to separate the thermal, intermediate and fast components of the neutron fluence. This detector was used to measure the neutron fluence at hundred points around the primary container of the first Mexican Nuclear Power plant 'Laguna Verde'. This last detector was also used to determine the neutron fluence in some points of interest, around and inside a low scattering neutron room at the 'Centro de Metrologia de Radiaciones Ionizantes' of the ININ, to know the background neutron field produced by the neutron sources used there. The design of the two neutron detector and the results obtained for each of the surveying facilities, are described in this work. (Author)

  2. Three-dimensional RAMA fluence methodology benchmarking

    This paper describes the benchmarking of the RAMA Fluence Methodology software, that has been performed in accordance with U. S. Nuclear Regulatory Commission Regulatory Guide 1.190. The RAMA Fluence Methodology has been developed by TransWare Enterprises Inc. through funding provided by the Electric Power Research Inst., Inc. (EPRI) and the Boiling Water Reactor Vessel and Internals Project (BWRVIP). The purpose of the software is to provide an accurate method for calculating neutron fluence in BWR pressure vessels and internal components. The Methodology incorporates a three-dimensional deterministic transport solution with flexible arbitrary geometry representation of reactor system components, previously available only with Monte Carlo solution techniques. Benchmarking was performed on measurements obtained from three standard benchmark problems which include the Pool Criticality Assembly (PCA), VENUS-3, and H. B. Robinson Unit 2 benchmarks, and on flux wire measurements obtained from two BWR nuclear plants. The calculated to measured (C/M) ratios range from 0.93 to 1.04 demonstrating the accuracy of the RAMA Fluence Methodology in predicting neutron flux, fluence, and dosimetry activation. (authors)

  3. A microscale approach for simple and rapid monitoring of cell growth and lipid accumulation in Neochloris oleoabundans.

    Kwak, Ho Seok; Kim, Jaoon Young Hwan; Sim, Sang Jun

    2015-10-01

    Due to the increasing environmental problems caused by the use of fossil fuels, microalgae have been spotlighted as renewable resources to produce biomass and biofuels. Therefore, the investigation of the optimum culture conditions of microalgae in a short time is one of the important factors for improving growth and lipid productivity. Herein, we developed a PDMS-based high-throughput screening system to rapidly and easily determine the optimum conditions for high-density culture and lipid accumulation of Neochloris oleoabundans. Using the microreactor, we were able to find the optimal culture conditions of N. oleoabundans within 5 days by rapid and parallel monitoring growth and lipid induction under diverse conditions of light intensity, pH, CO2 and nitrate concentration. We found that the maximum growth rate (µ max = 2.13 day(-1)) achieved in the microreactor was 1.58-fold higher than that in a flask (µ max = 1.34 day(-1)) at the light intensity of 40 µmol photons m(-2) s(-1), 5 % CO2 (v/v), pH 7.5 and 7 mM nitrate. In addition, we observed that the accumulation of lipid in the microreactor was 1.5-fold faster than in a flask under optimum culture condition. These results show that the microscale approach has the great potential for improving growth and lipid productivity by high-throughput screening of diverse optimum conditions. PMID:26209175

  4. Western Mediterranean coastal waters--monitoring PCBs and pesticides accumulation in Mytilus galloprovincialis by active mussel watching: the Mytilos project.

    Scarpato, Alfonso; Romanelli, Giulia; Galgani, Francois; Andral, Bruno; Amici, Marina; Giordano, Pierpaolo; Caixach, Josep; Calvo, Monica; Campillo, Juan Antonio; Albadalejo, José Benedicto; Cento, Alessandro; BenBrahim, Samir; Sammari, Cherif; Deudero, Salud; Boulahdid, Mostefa; Giovanardi, Franco

    2010-04-01

    In order to evaluate the contamination levels in the Western Mediterranean basin, the active mussel watch methodology has been applied. This methodology consists of mussel transplantation (Mytilus galloprovincialis) from non impacted areas to selected coastal areas, characterised by potential impact from the continent due to contaminating sources. The areas of interest were selected along the entire coastal development of the Western Mediterranean sea, 122 sites in total. The time of mussel caging exposure was 12 weeks. The project was co-financed in the frame of the Interreg IIIB Meddoc Programme, aimed at determining the overall chemical quality of the Mediterranean sea, consistent with the Water Framework Directive 2000/60. Several partners representative of the coastal Mediterranean Countries were involved in the Project, with the purpose of building up a common surveillance network, adopting shared methodologies. In this paper we present the results of three yearly monitoring campaigns (2004, 2005, 2006) carried out along the coasts of Italy, France, Spain, Morocco, Algeria and Tunisia, including the coastal environment of Baleares, Sicily, Sardinia and Corsica. The contamination levels of Pesticides (DDT and its metabolites, Hexachlorocyclohexane isomers alpha and gamma) and Polychlorinated biphenyls, are reported and discussed. Statistical elaborations performed on the original data set were mainly aimed at validating the raw sample distributions, by means of the Johnson method. Both DD and PCB species frequency distributions have been approximated to appropriate theoretical distributions, belonging to the Log-normal and Bounded families. By integrating the related Probability Density Functions (p.d.f.), different accumulation values for DDT, DDD and DDE and PCB species have been estimated, corresponding to fixed percentage points of the area under the respective curves. By choosing appropriate probability level boundaries (33rd and 66th percentile

  5. What is an acceptably smoothed fluence? Dosimetric and delivery considerations for dynamic sliding window IMRT

    The study summarised in this report aimed to investigate the interplay between fluence complexity, dose calculation algorithms, dose calculation spatial resolution and delivery characteristics (monitor units, effective field width and dose delivery against dose prediction agreement) was investigated. A sample set of complex planning cases was selected and tested using a commercial treatment planning system capable of inverse optimisation and equipped with tools to tune fluence smoothness. A set of increasingly smoothed fluence patterns was correlated to a generalised expression of the Modulation Index (MI) concept, in nature independent from the specific planning system used that could therefore be recommended as a predictor to score fluence 'quality' at a very early stage of the IMRT QA process. Fluence complexity was also correlated to delivery accuracy and characteristics in terms of number of MU, dynamic window width and agreement between calculation and measurement (expressed as percentage of field area with a γ > 1 (%FA)) when comparing calculated vs. delivered modulated dose maps. Different resolutions of the calculation grid and different photon dose algorithms (pencil beam and anisotropic analytical algorithm) were used for the investigations. i) MI can be used as a reliable parameter to test different approaches/algorithms to smooth fluences implemented in a TPS, and to identify the preferable default values for the smoothing parameters if appropriate tools are implemented; ii) a MI threshold set at MI < 19 could ensure that the planned beams are safely and accurately delivered within stringent quality criteria; iii) a reduction in fluence complexity is strictly correlated to a corresponding reduction in MUs, as well as to a decrease of the average sliding window width (for dynamic IMRT delivery); iv) a smoother fluence results in a reduction of dose in the healthy tissue with a potentially relevant clinical benefit; v) increasing the smoothing

  6. Neutron fluence spectrometry using disk activation

    A simple and robust detector for spectrometry of environmental neutrons has been developed. The technique is based on neutron activation of a series of different metal disks followed by low-level gamma-ray spectrometry of the activated disks and subsequent neutron spectrum unfolding. The technique is similar to foil activation but here the applied neutron fluence rates are much lower than usually in the case of foil activation. The detector has been tested in quasi mono-energetic neutron fields with fluence rates in the order of 1000-10000 cm-2 s-1, where the obtained spectra showed good agreement with spectra measured using a Bonner sphere spectrometer. The detector has also been tested using an AmBe source and at a neutron fluence rate of about 40 cm-2 s-1, again, a good agreement with the assumed spectrum was achieved

  7. Automatic semi-continuous accumulation chamber for diffuse gas emissions monitoring in volcanic and non-volcanic areas

    Lelli, Matteo; Raco, Brunella; Norelli, Francesco; Virgili, Giorgio; Continanza, Davide

    2016-04-01

    Since various decades the accumulation chamber method is intensively used in monitoring activities of diffuse gas emissions in volcanic areas. Although some improvements have been performed in terms of sensitivity and reproducibility of the detectors, the equipment used for measurement of gas emissions temporal variation usually requires expensive and bulky equipment. The unit described in this work is a low cost, easy to install-and-manage instrument that will make possible the creation of low-cost monitoring networks. The Non-Dispersive Infrared detector used has a concentration range of 0-5% CO2, but the substitution with other detector (range 0-5000 ppm) is possible and very easy. Power supply unit has a 12V, 7Ah battery, which is recharged by a 35W solar panel (equipped with charge regulator). The control unit contains a custom programmed CPU and the remote transmission is assured by a GPRS modem. The chamber is activated by DataLogger unit, using a linear actuator between the closed position (sampling) and closed position (idle). A probe for the measure of soil temperature, soil electrical conductivity, soil volumetric water content, air pressure and air temperature is assembled on the device, which is already arranged for the connection of others external sensors, including an automatic weather station. The automatic station has been tested on the field at Lipari island (Sicily, Italy) during a period of three months, performing CO2 flux measurement (and also weather parameters), each 1 hour. The possibility to measure in semi-continuous mode, and at the same time, the gas fluxes from soil and many external parameters, helps the time series analysis aimed to the identification of gas flux anomalies due to variations in deep system (e.g. onset of volcanic crises) from those triggered by external conditions.

  8. Electrochemical monitoring of phytochelatin accumulation in Nicotiana tabacum cells exposed to sub-cytotoxic and cytotoxic levels of cadmium

    Fojta, Miroslav [Laboratory of Biophysical Chemistry and Molecular Oncology, Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, 612 65 Brno (Czech Republic)]. E-mail: fojta@ibp.cz; Fojtova, Miloslava [Laboratory of Molecular Epigenetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, 612 65 Brno (Czech Republic); Havran, Ludek [Laboratory of Biophysical Chemistry and Molecular Oncology, Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, 612 65 Brno (Czech Republic); Pivonkova, Hana [Laboratory of Biophysical Chemistry and Molecular Oncology, Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, 612 65 Brno (Czech Republic); Dorcak, Vlastimil [Laboratory of Biophysical Chemistry and Molecular Oncology, Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, 612 65 Brno (Czech Republic); Sestakova, Ivana [J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Prague 8 (Czech Republic)

    2006-02-03

    Cadmium belongs to the most dangerous environmental pollutants among the toxic heavy metals seriously affecting vital functions in both animal and plant cells. It has been previously shown that cadmium ions at 50-100 {mu}M concentrations caused tobacco BY-2 (TBY-2) cells to enter apoptosis within several days of exposure. Phytochelatins (PCs), the 'plant metallothioneins', are cysteine-rich peptides involved in detoxification of heavy metals in plants. The PCs are synthesized in response to the heavy metal exposure. In this paper, we utilized electrochemical analysis to monitor accumulation of PCs in the TBY-2 cells exposed to cadmium ions. Measurements of a characteristic PC signal at mercury electrode in the presence of cobalt ions made it possible to detect changes in the cellular PC levels during the time of cultivation, starting from 30 min after exposure. Upon TBY-2 cultivation in the presence of cytotoxic cadmium concentrations, the PC levels remarkably increased during the pre-apoptotic phase and reached a limiting value at cultivation times coinciding with apoptosis trigger. The PC level observed for a sub-cytotoxic cadmium concentration (10 {mu}M) was about three-times lower than that observed for the 50 or 100 {mu}M cadmium ions after 5 days of exposure. We show that using a simple electrochemical analysis, synthesis of PCs in plant cells can be easily followed in parallel with other tests of the cellular response to the toxic heavy metal stress.

  9. The spatial distribution, accumulation and potential source of seldom monitored trace elements in sediments of Three Gorges Reservoir, China.

    Han, Lanfang; Gao, Bo; Zhou, Huaidong; Xu, Dongyu; Wei, Xin; Gao, Li

    2015-01-01

    The alteration of hydrologic condition of Three Gorges Reservoir (TGR) after impoundment has caused numerous environmental changes. This study investigated the distribution, accumulation and potential sources of the seldom monitored trace elements (SMTEs) in sediments from three tributaries (ZY, MX and CT) and one mainstream (CJ) in TGR during different seasons. The average contents of most SMTEs excluding Sb in the winter were similar to that in the summer. For Sb, its average concentrations in the summer and winter were roughly six and three times higher than its background value, respectively. Contamination factor (CF) and geoaccumulation index (Igeo) demonstrated that most of the sediments were obviously contaminated by Sb. The enrichment factors (EF) of Ga and Sb were higher than 2.0, revealing the possible anthropogenic inputs; However, the EFs of other SMTEs were lower than 1.5, indicating the natural inputs. Correlation and principal component analysis suggested the most SMTEs were positively correlated with major elements (Cr, Mn, Cu, Zn, As, Cd and Pb) and clay contents, which implies that SMTEs had the same sources with these major metals, and the fine particles might be a major carrier for transporting SMTEs from the rivers to the TGR. PMID:26538153

  10. X-ray attenuation measurements for high-temperature materials characterization and in-situ monitoring of damage accumulation

    Baaklini, G.Y.

    1991-01-01

    The scope of this study was to develop and apply x-ray attenuation measurement systems that are capable of (1) characterizing density variations in high-temperature materials, e.g., monolithic ceramics and ceramic and intermetallic-matrix composites, and (2) noninvasively monitoring damage accumulation and failure sequences in ceramic-matrix composites under room-temperature tensile testing. This thesis resulted in the development of (1) a point-scan digital radiography system and (2) an in-situ x-ray material testing system. The former is used to characterize silicon carbide and silicon nitride specimens, and the latter is used to image the failure behavior of silicon carbide fiber reinforced reaction bonded silicon nitride matrix composites. Further, state of the art x-ray computed tomography is investigated to determine its capabilities and limitations in characterizing density variations of subscale engine components. Microfocus radiography, conventional radiography, scanning acoustic microscopy, and metallography are used to substantiate the x-ray computed tomography findings.

  11. Transformation of YSZ under high fluence argon ion implantation

    Usov, I.O. [Los Alamos National Laboratory, Los Alamos, NM (United States); Rubanov, S. [Bio21 Institute, The University of Melbourne, Melbourne (Australia); Won, J. [Division of Electron Microscopic Research, Korea Basic Science Institute, Deajeon (Korea, Republic of); Suvorova, A.A., E-mail: alexandra.suvorova@uwa.edu.au [Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley (Australia)

    2014-05-01

    In this work, we present the effect of extremely high fluence ion implantation on microstructure of single crystalline YSZ samples with three major low index orientations: (1 0 0), (1 1 0) and (1 1 1). The samples were implanted at room temperature with 150 keV Ar{sup +} ions to a fluence of 1 × 10{sup 17} Ar/cm{sup −2} corresponding to the peak damage level of ∼120 dpa and peak Ar atom concentration of ∼12 at.%. Rutherford backscattering/channeling spectrometry (RBS/C), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and associated analytical tools were used to determine the orientation dependent damage, surface morphology, and microstructure modifications of the implanted layers. Ar{sup +} ion implantation resulted in formation of severely damaged layers, which however remained crystalline. The damage peak maximum, determined by RBS/C, indicated that the fourth damage accumulation stage, previously predicted for Ar-implanted YSZ, was achieved. The (1 1 0) oriented YSZ demonstrated slightly better radiation tolerance, as observed by RBS/C, compared to the other low index orientations. Microstructural studies revealed large cavities aligned parallel to the specimen surface, which emerged in a form of circular blisters on the surface. The origin of the cavities was related to the segregation of Ar atoms into pressurized gas filled bubbles. The crystallographic anisotropy of microstructural parameters (thickness of the damages layer, surface blister density and diameter, cavity dimensions) remains uncertain.

  12. Measured thermal and fast neutron fluence rates ATR Cycle 101-B, October 11, 1993--November 27, 1993

    This report contains the thermal (2200 m/s) and fast (E>lMeV) neutron fluence rate data for ATR Cycle 101-B which were measured by the Radiation Measurements Laboratory (RML) as requested by the Power Reactor Programs (ATR Experiments) Radiation Measurements Work Order. This report contains fluence rate values corresponding to the particular elevations (relative to the 80 ft. core elevation) where the measurements were taken. The data in this report consists of (1) a table of the ATR power history and distribution, (2) a hard copy listing of all thermal and fast neutron fluence rates, (3) plots of both the thermal and fast neutron fluence rates, and (4) a magnetic record (3.5 inch diskette) containing a listing of only the fast neutron fluence rates, their assigned elevations proper header identification of all monitor positions contained herein

  13. Effects of laser focusing and fluence on the analysis of pellets of plant materials by laser-induced breakdown spectroscopy

    Gustinelli Arantes de Carvalho, Gabriel [Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Av. Centenario 303, 13416-000 Piracicaba, SP (Brazil); Santos, Dario [Universidade Federal de Sao Paulo - UNIFESP, Campus Diadema, Rua Prof. Artur Riedel 275, 09972-270 Diadema, SP (Brazil); Nunes, Lidiane Cristina [Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Av. Centenario 303, 13416-000 Piracicaba, SP (Brazil); Gomes, Marcos da Silva [Departamento de Quimica, Universidade Federal de Sao Carlos, Rod. Washington Luis, km 235, 13565-905 Sao Carlos, SP (Brazil); Leme, Flavio de Oliveira [Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Av. Centenario 303, 13416-000 Piracicaba, SP (Brazil); Krug, Francisco Jose, E-mail: fjkrug@cena.usp.br [Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Av. Centenario 303, 13416-000 Piracicaba, SP (Brazil)

    2012-08-15

    The effects of laser focusing and fluence on LIBS analysis of pellets of plant leaves was evaluated. A Q-switched Nd:YAG laser (5 ns, 10 Hz, 1064 nm) was used and the emission signals were collected by lenses into an optical fiber coupled to a spectrometer with Echelle optics and ICCD. Data were acquired from the accumulation of 20 laser pulses at 2.0 {mu}s delay and 5.0 {mu}s integration time gate. The emission signal intensities increased with both laser fluence and spot size. Higher sensitivities for Ca, K, Mg, P, Al, B, Cu, Fe, Mn, and Zn determinations were observed for fluences in the range from 25 to 60 J cm{sup -2}. Coefficients of variation of site-to-site measurements were generally lower than 10% (n = 30 sites, 20 laser pulses/site) for a fluence of 50 J cm{sup -2} and 750 {mu}m spot size. For most elements, there is an indication that accuracy is improved with higher fluences. - Highlights: Black-Right-Pointing-Pointer Laser focusing and fluence affect the quality of LIBS results. Black-Right-Pointing-Pointer Improvements on sensitivity and precision were observed for most analytes. Black-Right-Pointing-Pointer Matrix effects can be minimized by choosing the most appropriate fluence.

  14. Isotopic dependence of GCR fluence behind shielding

    In this paper we consider the effects of the isotopic composition of the primary galactic cosmic rays (GCR), nuclear fragmentation cross sections, and isotopic-grid on the solution to transport models used for shielding studies. Satellite measurements are used to describe the isotopic composition of the GCR. For the nuclear interaction data-base and transport solution, we use the quantum multiple scattering theory of nuclear fragmentation (QMSFRG) and high-charge and energy (HZETRN) transport code, respectively. The QMSFRG model is shown to accurately describe existing fragmentation data including proper description of the odd-even effects as function of the iso-spin dependence on the projectile nucleus. The principle finding of this study is that large errors (±100%) will occur in the mass-fluence spectra when comparing transport models that use a complete isotopic-grid (∼170 ions) to ones that use a reduced isotopic-grid, for example the 59 ion-grid used in the HZETRN code in the past; however, less significant errors (<+/-20%) occur in the elemental-fluence spectra. Because a complete isotopic-grid is readily handled on small computer workstations and is needed for several applications studying GCR propagation and scattering, it is recommended that they be used for future GCR studies

  15. Isotopic dependence of GCR fluence behind shielding

    Cucinotta, Francis A. [NASA, Lyndon B. Johnson Space Center, Houston, TX 77058 (United States)]. E-mail: Francis.A.Cucinotta@nasa.gov; Wilson, John W. [NASA, Langley Research Center, Hampton, VA 23664 (United States); Saganti, Premkumar [Prairie View A and M, Prairie View, TX 94720 (United States); Hu, Xiaodong [NASA, Lyndon B. Johnson Space Center, Houston, TX 77058 (United States); Kim, Myung-Hee Y. [NASA, Lyndon B. Johnson Space Center, Houston, TX 77058 (United States); Cleghorn, Timothy [NASA, Lyndon B. Johnson Space Center, Houston, TX 77058 (United States); Zeitlin, Cary [Lawrence Berkeley National Laboratory Berkeley, CA 94720 (United States); Tripathi, Ram K. [NASA, Langley Research Center, Hampton, VA 23664 (United States)

    2006-10-15

    In this paper we consider the effects of the isotopic composition of the primary galactic cosmic rays (GCR), nuclear fragmentation cross sections, and isotopic-grid on the solution to transport models used for shielding studies. Satellite measurements are used to describe the isotopic composition of the GCR. For the nuclear interaction data-base and transport solution, we use the quantum multiple scattering theory of nuclear fragmentation (QMSFRG) and high-charge and energy (HZETRN) transport code, respectively. The QMSFRG model is shown to accurately describe existing fragmentation data including proper description of the odd-even effects as function of the iso-spin dependence on the projectile nucleus. The principle finding of this study is that large errors ({+-}100%) will occur in the mass-fluence spectra when comparing transport models that use a complete isotopic-grid ({approx}170 ions) to ones that use a reduced isotopic-grid, for example the 59 ion-grid used in the HZETRN code in the past; however, less significant errors (<+/-20%) occur in the elemental-fluence spectra. Because a complete isotopic-grid is readily handled on small computer workstations and is needed for several applications studying GCR propagation and scattering, it is recommended that they be used for future GCR studies.

  16. Isotopic Dependence of GCR Fluence behind Shielding

    Cucinotta, Francis A.; Wilson, John W.; Saganti, Premkumar; Kim, Myung-Hee Y.; Cleghorn, Timothy; Zeitlin, Cary; Tripathi, Ram K.

    2006-01-01

    In this paper we consider the effects of the isotopic composition of the primary galactic cosmic rays (GCR), nuclear fragmentation cross-sections, and isotopic-grid on the solution to transport models used for shielding studies. Satellite measurements are used to describe the isotopic composition of the GCR. For the nuclear interaction data-base and transport solution, we use the quantum multiple-scattering theory of nuclear fragmentation (QMSFRG) and high-charge and energy (HZETRN) transport code, respectively. The QMSFRG model is shown to accurately describe existing fragmentation data including proper description of the odd-even effects as function of the iso-spin dependence on the projectile nucleus. The principle finding of this study is that large errors (+/-100%) will occur in the mass-fluence spectra when comparing transport models that use a complete isotopic-grid (approx.170 ions) to ones that use a reduced isotopic-grid, for example the 59 ion-grid used in the HZETRN code in the past, however less significant errors (<+/-20%) occur in the elemental-fluence spectra. Because a complete isotopic-grid is readily handled on small computer workstations and is needed for several applications studying GCR propagation and scattering, it is recommended that they be used for future GCR studies.

  17. Conceptual tokamak design at high neutron fluence

    For the future fusion reactor, it is important to design an experimental device that can be performed testing in-vessel components including tritium breeding modules relevant to the future fusion reactor with high neutron fluence. To realize this requirement, a conceptual tokamak design has been performed in accordance with plasma performance and shape at quasi-steady-state operation. One of the promising scenarios for this purpose is proposed to produce the plasma at the outward shifted radial position with a small minor radius for reasonable plasma parameters. From the analytical results, an appropriate space can be found for neutron shielding so that additional neutron shielding can be installed to protect the tokamak components from any neutron damages under the neutron fluence of 1 MWa m-2. Based on the structural analyses, a two-stage blanket module concept is proposed, i.e. one shielding block with the first wall assembly during high Q operation and two shielding blocks or additional tritium breeding modules during quasi-steady state operation

  18. Determination of the neutron fluence in the welding of the 'Core shroud' of the BWR reactor core

    With the purpose of defining the inspection frequency, in function of the embrittlement of the materials that compose the welding of the 'Core Shroud' or encircling of the core of a BWR type reactor, is necessary to know the neutron fluence received for this welding. In the work the calculated values of neutron fluence accumulated maxim (E > 1 MeV) during the first 8 operation cycles of the reactor are presented. The calculations were carried out according to the NRC Regulatory Guide 1.190, making use of the DORT code, which solves the transport equation in discreet ordinate in two dimensions (xy, rΘ, and rz). The results in 3D were obtained applying the Synthesis method according to the guide before mentioned. Results are presented for the horizontal welding H3, H4, and H5, showing the corresponding curves to the fluence accumulated to the cycle 8 and a projection for the cycle 14 is presented. (Author)

  19. Standard Test Method for Measuring Neutron Fluence Rate by Radioactivation of Cobalt and Silver

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method covers a suitable means of obtaining the thermal neutron fluence rate, or fluence, in well moderated nuclear reactor environments where the use of cadmium, as a thermal neutron shield as described in Method E262, is undesirable because of potential spectrum perturbations or of temperatures above the melting point of cadmium. 1.2 This test method describes a means of measuring a Westcott neutron fluence rate (Note 1) by activation of cobalt- and silver-foil monitors (See Terminology E170). The reaction 59Co(n,γ)60Co results in a well-defined gamma emitter having a half-life of 1925.28 days (1). The reaction 109Ag(n,˙γ) 110mAg results in a nuclide with a complex decay scheme which is well known and having a half-life of 249.76 days (1). Both cobalt and silver are available either in very pure form or alloyed with other metals such as aluminum. A reference source of cobalt in aluminum alloy to serve as a neutron fluence rate monitor wire standard is available from the National Institute ...

  20. Monte Carlo fluence simulation for prospective evaluation of interstitial photodynamic therapy treatment plans

    Cassidy, Jeffrey; Betz, Vaughn; Lilge, Lothar

    2015-03-01

    Photodynamic therapy (PDT) delivers a localized cytotoxic dose that is a function of tissue oxygen availability, photosensitive drug concentration, and light fluence. Providing safe and effective PDT requires an understanding of all three elements and the physiological response to the radicals generated. Interstitial PDT (IPDT) for solid tumours poses particular challenges due to complex organ geometries and the associated limitations for diffusion theory based fluence rate prediction, in addition to restricted access for light delivery and dose monitoring. As a first step towards enabling a complete prospective IPDT treatment-planning platform, we demonstrate use of our previously developed FullMonte tetrahedral Monte Carlo simulation engine for modeling of the interstitial fluence field due to intravesicular insertion of brief light sources. The goal is to enable a complete treatment planning and monitoring work flow analogous to that used in ionizing radiation therapy, including plan evaluation through dose-volume histograms and algorithmic treatment plan optimization. FullMonte is to our knowledge the fastest open-source tetrahedral MC light propagation software. Using custom hardware acceleration, we achieve 4x faster computing with 67x better power efficiency for limited-size meshes compared to the software. Ongoing work will improve the performance advantage to 16x with unlimited mesh size, enabling algorithmic plan optimization in reasonable time. Using FullMonte, we demonstrate significant new plan-evaluation capabilities including fluence field visualization, generation of organ dose-volume histograms, and rendering of isofluence surfaces for a representative bladder cancer mesh from a real patient. We also discuss the advantages of MC simulations for dose-volume histogram generation and the need for online personalized fluence-rate monitoring.

  1. The fluence effect of Ar++ bombardment in PPS

    The modifications induced by ion bombardment on the physical and chemical structures and on thermal, optical and electrical properties of poly(phenylene sulphide), PPS, were investigated. Thin PPS foils, 2, 6 and 125 μm thick were bombarded with Ar++ (700 keV) under initial vacuum of 10-6 torr. Changes in the chemical structure were monitored by infrared absorption spectroscopy (FTIR) and ultraviolet and visible spectroscopy (UV-VIS). Modifications in the relative atomic composition of the bombarded polymer samples were determined by elemental analysis (CHN) and Rutherford backscattering spectrometry (RBS). Processes resulting from ion implantation on the physical structure of PPS were followed by X-ray diffraction spectrometry (XRD), differential scanning calorimetry (DSC), solubility tests and electrical conductivity measurements. Thermal stability of these samples was established by thermogravimetric analysis (TGA). Ion bombardment induces electronic excitation and ionization of molecular species, which leads to crystallinity loss, chemical bonds disruptions and formation of free radicals. These reactive groups lead to the formation of cross-linking processes and absorption of atmospheric gases, like oxygen and nitrogen. Oxygen is combined with the polymer main chain, partaking in the cross-linking and in the formation of conjugated structures. Due to extensive bond conjugation the energy gap between valence and conduction bands diminishes. This process favors charge transport, leading to an increase of the macroscopic electrical conductivity. However, after bombardment, the oxygen absorption induces a continuous decrease of the conductivity, even after a period of six months. The samples irradiated with the highest fluences exhibit conductivities similar to those of semiconductors. A kinetic study of the thermal degradation of implanted samples indicates that the thermal stability, defined by the onset temperature and the activation energy of the process

  2. Fast approximate delivery of fluence maps: the VMAT case

    Balvert, Marleen; Craft, David

    2016-01-01

    In this article we provide a method to generate the trade-off between delivery time and fluence map matching quality for volumetric modulated arc therapy (VMAT). At the heart of our method lies a mathematical programming model that, for a given duration of delivery, optimizes leaf trajectories and dose rates such that the desired fluence map is reproduced as well as possible. This model was presented for the single map case in a companion paper (Fast approximate delivery of fluence maps: the ...

  3. Environmental monitoring to the sources of atmospheric emission by the Trad-MCN bioassay and analysis of the accumulative potential for uranium and fluoride

    The biomonitoring of the atmospheric contamination constitutes important procedure for adoption of environmental control measures. Biological assays have been employed to evaluate genotoxic agents in the atmosphere. The Tradescantia-micronucleus (Trad-MCN) assay has been extensively used in environmental monitoring owing to its efficiency in the detection of chromosomic damages in cytological preparations of easy execution. In this study we tested the viability of use of Trad-MCN with Tradescantia pallida cv. Purpurea for environmental monitoring in the Experimental Center Aramar (CEA), in Ipero - SP and its leaf accumulation capacity. The plants were exposed in situ, in flower-beds or flowerpots, established close to the sources of atmospheric emission. The bioassay was accomplished according to the usual protocol. The micronucleus frequencies were compared using the variance Kruskal-Wallis test. The obtained results indicated that the biomonitoring model adopted was not the ideal for the CEA, considering that the plant suffered the influence of climatic condition. However the plant showed to have accumulative potential for uranium. (author)

  4. Environmental monitoring to the sources of atmospheric emission by the Trad-MCN bioassay and analysis of the accumulative potential for uranium and fluoride

    Machado, Alessandra C.F.E., E-mail: alessandra@ctmsp.mar.mil.b [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), SP (Brazil). Div. de Monitoracao Ambiental; Ramos, Monique M.B., E-mail: monique@ctmsp.mar.mil.b [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), SP (Brazil). Div. de Analise de Seguranca; Alves, Edenise S., E-mail: ealves@ibot.sp.gov.b [Instituto de Botanica de Sao Paulo, Sao Paulo, SP (Brazil). Secao de Anatomia

    2009-07-01

    The biomonitoring of the atmospheric contamination constitutes important procedure for adoption of environmental control measures. Biological assays have been employed to evaluate genotoxic agents in the atmosphere. The Tradescantia-micronucleus (Trad-MCN) assay has been extensively used in environmental monitoring owing to its efficiency in the detection of chromosomic damages in cytological preparations of easy execution. In this study we tested the viability of use of Trad-MCN with Tradescantia pallida cv. Purpurea for environmental monitoring in the Experimental Center Aramar (CEA), in Ipero - SP and its leaf accumulation capacity. The plants were exposed in situ, in flower-beds or flowerpots, established close to the sources of atmospheric emission. The bioassay was accomplished according to the usual protocol. The micronucleus frequencies were compared using the variance Kruskal-Wallis test. The obtained results indicated that the biomonitoring model adopted was not the ideal for the CEA, considering that the plant suffered the influence of climatic condition. However the plant showed to have accumulative potential for uranium. (author)

  5. X ray attenuation measurements for high-temperature materials characterization and in-situ monitoring of damage accumulation. Ph. D. Thesis - Cleveland State Univ. , 1991

    Baaklini, G.Y.

    1992-03-01

    The scope of this dissertation is to develop and apply x ray attenuation measurement systems that are capable of: (1) characterizing density variations in high-temperature materials, e.g., monolithic ceramics, ceramic and intermetallic matrix composites, and (2) noninvasively monitoring damage accumulation and failure sequences in ceramic matrix composites under room temperature tensile testing. This dissertation results in the development of: (1) a point scan digital radiography system, and (2) an in-situ x ray material testing system. Radiographic evaluation before, during, and after loading shows the effect of preexisting volume flaws on the fracture behavior of composites. Results show that x ray film radiography can monitor damage accumulation during tensile loading. Matrix cracking, fiber matrix debonding, fiber bridging, and fiber pullout are imaged throughout the tensile loading of the specimens. Further in-situ radiography is found to be a practical technique for estimating interfacial shear strength between the silicon carbide fibers and the reaction bonded silicon nitride matrix. It is concluded that pretest, in-situ, and post test x ray imaging can provide for greater understanding of ceramic matrix composite mechanical behavior.

  6. Environmental monitoring of the area surrounding oil wells in Val d'Agri (Italy): element accumulation in bovine and ovine organs.

    Miedico, Oto; Iammarino, Marco; Paglia, Giuseppe; Tarallo, Marina; Mangiacotti, Michele; Chiaravalle, A Eugenio

    2016-06-01

    In this work, environmental heavy metal contamination in the Val d'Agri area of Southern Italy was monitored, measuring the accumulation of 18 heavy metals (U, Hg, Pb, Cd, As, Sr, Sn, V, Ni, Cr, Mo, Co, Cu, Zn, Ca, Mn, Fe, and Al) in the organs of animals raised in the surrounding area (kidney, lung, and liver of bovine and ovine species). Val d'Agri features various oil processing centers which are potentially a significant source of environmental pollution, making it essential to perform studies that will outline the state of the art on which any recovery plans and interventions may be developed. The analysis was carried out using official and accredited analytical methods based on inductively coupled plasma mass spectrometry, and the measurements were statistically processed in order to give a contribution to risk assessment. Even though five samples showed Pb and Cd concentrations above the limits defined in the European Commission Regulation (EC) No 1881/2006, the mean concentrations of most elements suggest that contamination in this area is low. Consequently, these results also suggest that there is no particular risk for human exposure to toxic trace elements. Nevertheless, the findings of this work confirm that element accumulation in ovine species is correlated with geographical livestock area. Therefore, ovine-specific organs might be used as bioindicators for monitoring contamination by specific toxic elements in exposed areas. PMID:27165602

  7. Validation of neutron-transport calculations in benchmark facilities for improved damage-fluence predictions

    An accurate determination of damage fluence accumulated by reactor pressure vessels (RPV) as a function of time is essential in order to evaluate the vessel integrity for both pressurized thermal shock (PTS) transients and end-of-life considerations. The desired accuracy for neutron exposure parameters such as displacements per atom or fluence (E > 1 MeV) is of the order of 20 to 30%. However, these types of accuracies can only be obtained realistically by validation of nuclear data and calculational methods in benchmark facilities. The purposes of this paper are to review the needs and requirements for benchmark experiments, to discuss the status of current benchmark experiments, to summarize results and conclusions obtained so far, and to suggest areas where further benchmarking is needed

  8. Absolute Neutron Fluence Measurements at the NIST Center for Neutron Research

    Yue, A.; Dewey, M.; Gilliam, D.; Nico, J.; Anderson, E.; Snow, M.; Greene, G.; Laptev, A.

    2015-10-01

    Precise, absolute fluence measurements of cold and thermal neutron beams are of primary importance to beam-type determinations of the neutron lifetime, measurements of standard neutron cross sections, and the development of standards for neutron dosimetry. At the National Institute of Standards and Technology (NIST), a totally absorbing neutron detector based on absolute counting of the 10B(n,α1)7Li reaction 478 keV gamma ray has been used to perform fluence measurements with a precision of 0.06%. This detector has been used to improve the neutron fluence determination in the 2000 NIST beam neutron lifetime by a factor of five, significantly reducing the uncertainty in the lifetime result. Ongoing and possible future uses of the Alpha-Gamma device include 1) Calibration of the neutron fluence monitors that will be used in the upcoming NIST beam neutron lifetime measurement BL2; 2) The first direct, absolute measurement of the 6Li(n,t)4He neutron cross section at sub-thermal neutron energy; 3) Measurements of the 10B(n, γ)11B and 235U(n,f) neutron cross sections; 4) A re-calibration of the national neutron standard NBS-1. The apparatus, measurement technique, and applications will be discussed.

  9. Irradiation Programs and Test Plans to Assess High-Fluence Irradiation Assisted Stress Corrosion Cracking Susceptibility.

    Teysseyre, Sebastien [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    . Irradiation assisted stress corrosion cracking (IASCC) is a known issue in current reactors. In a 60 year lifetime, reactor core internals may experience fluence levels up to 15 dpa for boiling water reactors (BWR) and 100+ dpa for pressurized water reactors (PWR). To support a safe operation of our fleet of reactors and maintain their economic viability it is important to be able to predict any evolution of material behaviors as reactors age and therefore fluence accumulated by reactor core component increases. For PWR reactors, the difficulty to predict high fluence behavior comes from the fact that there is not a consensus of the mechanism of IASCC and that little data is available. It is however possible to use the current state of knowledge on the evolution of irradiated microstructure and on the processes that influences IASCC to emit hypotheses. This report identifies several potential changes in microstructure and proposes to identify their potential impact of IASCC. The susceptibility of a component to high fluence IASCC is considered to not only depends on the intrinsic IASCC susceptibility of the component due to radiation effects on the material but to also be related to the evolution of the loading history of the material and interaction with the environment as total fluence increases. Single variation type experiments are proposed to be performed with materials that are representative of PWR condition and with materials irradiated in other conditions. To address the lack of IASCC propagation and initiation data generated with material irradiated in PWR condition, it is proposed to investigate the effect of spectrum and flux rate on the evolution of microstructure. A long term irradiation, aimed to generate a well-controlled irradiation history on a set on selected materials is also proposed for consideration. For BWR, the study of available data permitted to identify an area of concern for long term performance of component. The efficiency of

  10. Vectorial and plane energy fluences - useful concepts in radiation physics

    The vectorial physical quantities describing the radiation field are defined in this report. The use of these quantities is rare in the radiation dosimetry literature since a knowledge of the directions of motion of the ionizing particle is often uninteresting when determining absorbed doses. However the plane energy fluence rate is a useful quantity in cases with plane irradiation geometries. The plane energy fluence rate is closely related to the vectorial energy fluence rate. The backscattering properties of a medium can be expressed in terms either of its albedo or its reflection-coefficient (backscatter-coefficient). These quantities are discussed in order to derive useful relations between the plane energy fluence and the energy fluence at points on an extended plane surface. Examples are also given of erroneous use of energy fluence instead of vectorial or plane energy fluence. The examples are taken from roentgen diagnostic examinations. To prevent further mistakes it could be valuable if the quantities of vectorial and plane fluences were introduced in text books in radiation dosimetry. Awaiting for this, this report may hopefully be useful. (E.R.)

  11. Online neutron fluence measurement at University Hospital Essen neutron therapy facility using gallium arsenide LEDs

    The detector and sensor group of the West German Proton Therapy Centre (WPE) has developed a novel real-time neutron fluence monitor based on tiny, inexpensive, commercially available GaAs-LEDs. The linear detection range for d(14)+Be neutrons was evaluated to be 5.0 × 108–2.0 × 1011 neutron.cm−2. However, this monitor can be used universally for neutrons of any energy distribution. Using scaling factors, fluence calibration curves for 1 MeV and 14 MeV D+T fusion neutrons have been calculated. The sensitivity of the detector increases with increasing neutron energy. This makes it suitable for the detection of high-energy neutrons, providing an extra advantage for use at a proton therapy facility where there is a high proportion of high-energy neutrons. The detector is practically not sensitive to photons. A prototype of the online GaAs-LED based neutron fluence monitor has been tested successfully at University Hospital Essen neutron therapy facility and will be implemented at WPE in the near future.

  12. Photoluminescence in large fluence radiation irradiated space silicon solar cells

    Hisamatsu, Tadashi; Kawasaki, Osamu; Matsuda, Sumio [National Space Development Agency of Japan, Tsukuba, Ibaraki (Japan). Tsukuba Space Center; Tsukamoto, Kazuyoshi

    1997-03-01

    Photoluminescence spectroscopy measurements were carried out for silicon 50{mu}m BSFR space solar cells irradiated with 1MeV electrons with a fluence exceeding 1 x 10{sup 16} e/cm{sup 2} and 10MeV protons with a fluence exceeding 1 x 10{sup 13} p/cm{sup 2}. The results were compared with the previous result performed in a relative low fluence region, and the radiation-induced defects which cause anomalous degradation of the cell performance in such large fluence regions were discussed. As far as we know, this is the first report which presents the PL measurement results at 4.2K of the large fluence radiation irradiated silicon solar cells. (author)

  13. Damage response to irradiation temperature and ion fluence in C+-irradiated 6H-SiC

    Irradiation experiments have been performed 60 degree off the surface normal for 6H-SiC single crystals at various temperatures (185--870 K) using 550 keV C+ ions over a fluence range from 1 x 1018 to 5 x 1019 ions/m2. Atomic disorder on the Si sublattice, as determined by in-situ RBS/channeling analysis, ranged from dilute defects to complete amorphization. The critical amorphization dose of ∼0.23 dpa (on the Si sublattice) at 185 K has been determined. Asymmetric shapes in angular yield profiles across the crystallographic axis left-angle 0001 right-angle emerged above 1.5 x 1019 C+/m2 (∼0.05 dpa in the near-surface region), which might be associated with the lattice disturbance in the crystal structure. A gradual decrease in half-angular width was observed with the increase of ion fluence in the experiment. The minimum yield exhibits a rather linear relationship with ion dose at the surface. Post-irradiation annealing at the irradiation temperature 470 and 670 K. Results also show that low fluence (18 C+/m2) irradiation at 185 K followed by thermal annealing results in similar defect concentrations to irradiation at that same temperature to the same ion fluence. thus, at low fluences, the accumulated defects are in thermal equilibrium with the structure

  14. SU-E-I-10: Automatic Monitoring of Accumulated Dose Indices From DICOM RDSR to Improve Radiation Safety in X-Ray Angiography

    Purpose: To investigate the potential benefits of automatic monitoring of accumulated patient and staff dose indicators, i.e., CAK and KAP, from DICOM Radiation Dose Structured Reports (RDSR) in x-ray angiography (XA). Methods: Recently RDSR has enabled the convenient aggregation of dose indices and technique parameters for XA procedures. The information contained in RDSR objects for three XA systems, dedicated to different types of clinical procedures, has been collected and aggregated in a database for over one year using a system developed with open-source software at the Karolinska University Hospital. Patient weight was complemented to the RDSR data via an interface with the Hospital Information System (HIS). Results: The linearly approximated trend in KAP over a time period of a year for cerebrovascular, pelvic/peripheral vascular, and cardiovascular procedures showed a decrease of 12%, 20%, and 14%, respectively. The decrease was mainly due to hardware/software upgrades and new low-dose imaging protocols, and partially due to ongoing systematic radiation safety education of the clinical staff. The CAK was in excess of 3 Gy for 15 procedures, and exceeded 5 Gy for 3 procedures. The dose indices have also shown a significant dependence on patient weight for cardiovascular and pelvic/peripheral vascular procedures; a 10 kg shift in mean patient weight can result in a dose index increase of 25%. Conclusion: Automatic monitoring of accumulated dose indices can be utilized to notify the clinical staff and medical physicists when the dose index has exceeded a predetermined action level. This allows for convenient and systematic follow-up of patients in risk of developing deterministic skin injuries. Furthermore, trend analyses of dose indices over time is a valuable resource for the identification of potential positive or negative effects (dose increase/decrease) from changes in hardware, software, and clinical work habits

  15. SU-E-I-10: Automatic Monitoring of Accumulated Dose Indices From DICOM RDSR to Improve Radiation Safety in X-Ray Angiography

    Omar, A; Bujila, R; Nowik, P; Karambatsakidou, A [Karolinska University Hospital, Stockholm (Sweden)

    2014-06-01

    Purpose: To investigate the potential benefits of automatic monitoring of accumulated patient and staff dose indicators, i.e., CAK and KAP, from DICOM Radiation Dose Structured Reports (RDSR) in x-ray angiography (XA). Methods: Recently RDSR has enabled the convenient aggregation of dose indices and technique parameters for XA procedures. The information contained in RDSR objects for three XA systems, dedicated to different types of clinical procedures, has been collected and aggregated in a database for over one year using a system developed with open-source software at the Karolinska University Hospital. Patient weight was complemented to the RDSR data via an interface with the Hospital Information System (HIS). Results: The linearly approximated trend in KAP over a time period of a year for cerebrovascular, pelvic/peripheral vascular, and cardiovascular procedures showed a decrease of 12%, 20%, and 14%, respectively. The decrease was mainly due to hardware/software upgrades and new low-dose imaging protocols, and partially due to ongoing systematic radiation safety education of the clinical staff. The CAK was in excess of 3 Gy for 15 procedures, and exceeded 5 Gy for 3 procedures. The dose indices have also shown a significant dependence on patient weight for cardiovascular and pelvic/peripheral vascular procedures; a 10 kg shift in mean patient weight can result in a dose index increase of 25%. Conclusion: Automatic monitoring of accumulated dose indices can be utilized to notify the clinical staff and medical physicists when the dose index has exceeded a predetermined action level. This allows for convenient and systematic follow-up of patients in risk of developing deterministic skin injuries. Furthermore, trend analyses of dose indices over time is a valuable resource for the identification of potential positive or negative effects (dose increase/decrease) from changes in hardware, software, and clinical work habits.

  16. Probability model for worst case solar proton event fluences

    The effects that solar proton events have on microelectronics and solar arrays are important considerations for spacecraft in geostationary orbits, polar orbits and on interplanetary missions. A predictive model of worst case solar proton event fluences is presented. It allows the expected worst case event fluence to be calculated for a given confidence level and for periods of time corresponding to space missions. The proton energy range is from >1 to >300 MeV, so that the model is useful for a variety of radiation effects applications. For each proton energy threshold, the maximum entropy principle is used to select the initial distribution of solar proton event fluences. This turns out to be a truncated power law, i.e., a power law for smaller event fluences that smoothly approaches zero at a maximum fluence. The strong agreement of the distribution with satellite data for the last three solar cycles indicates this description captures the essential features of a solar proton event fluence distribution. Extreme value theory is then applied to the initial distribution of events to obtain the model of worst case fluences

  17. Fast approximate delivery of fluence maps: the single map case

    Craft, David

    2016-01-01

    In this first paper of a two-paper series, we present a method for optimizing the dynamic delivery of fluence maps in radiation therapy. For a given fluence map and a given delivery time, the optimization of the leaf trajectories of a multi-leaf collimator to approximately form the given fluence map is a non-convex optimization problem. Its general solution has not been addressed in the literature, despite the fact that dynamic delivery of fluence maps has long been a common approach to intensity modulated radiation therapy. We model the leaf trajectory and dose rate optimization as a non-convex continuous optimization problem and solve it by an interior point method from randomly initialized feasible starting solutions. We demonstrate the method on a fluence map from a prostate case and a larger fluence map from a head-and-neck case. While useful for static beam IMRT delivery, our main motivation for this work is the extension to the case of sequential fluence map delivery, i.e. the case of VMAT, which is th...

  18. Neutron fluence estimation for corrosion coupons in PHWRs and strategy for achieving the desired fluence

    Properties of nuclear reactor structural materials undergo mechanical changes due to neutron irradiation. In order to study the radiation effect on various structural materials used in Pressurised Heavy Water Reactors (PHWR) and Advanced Heavy water Reactor (AHWR), in-pile irradiation of structural materials is required. The 19 pin PHWR (220 MWe) cluster was modified to hold the samples of structural material such that the same can be easily loaded in PHWR (220 MWe) for in-pile irradiation purposes. Such clusters have been termed as specimen clusters. The objective for the estimation of neutron fluence is to load the specimen cluster in the core such that it causes minimum perturbation to the normal reactor operation and it provides maximum fast neutron fluence (neutron flux times the irradiation time in seconds i.e. neutrons/cm2) for the minimum irradiation time. For the purpose of irradiation of structural material in PHWR (220 MWe), different locations of the sample material within the specimen cluster were considered and the loading of specimen cluster at different locations in the core was studied to achieve the desired objective. (author)

  19. Radiochemical evaluation of activation detectors for fluence determination of fast neutrons

    For monitoring of radiation embrittlement of reactor pressure vessels, irradiation experiments to determine the fluence of fast neutrons are carried out. The activation detectors used for this purpose are based on the following nuclear reactions: Fe54(n,p)Mn54 Nb93(n,n')Nb93m Th232(n,f)Cs137. The criteria, which led to the selection of these activation detectors, are discussed. The evaluation via chemical preparation and radiation measurement as well as the problems of calibration yield control and interferences are described. The experience made to date shows that - depending on detector and effort - the disintegration rates can be measured during routine measurements with an accuracy of 5 to 25%. The error range of the determined neutron fluence is 15 to 30%. The results of the three activation detectors are in agreement within this error range. (orig.)

  20. Thermal and structural properties of low-fluence irradiated graphite

    Lexa, Dusan; Dauke, Michael

    2009-02-01

    The release of Wigner energy from graphite irradiated by fast neutrons at a TRIGA Mark II research reactor has been studied by differential scanning calorimetry and simultaneous differential scanning calorimetry / synchrotron powder X-ray diffraction between 25 and 725 °C at a heating rate of 10 °C min -1. The graphite, having been subject to a fast-neutron fluence from 5.67 × 10 20 to 1.13 × 10 22 n m -2 at a fast-neutron flux ( E > 0.1 MeV) of 7.88 × 10 16 n m -2 s -1 and at temperatures not exceeding 100 °C, exhibits Wigner energies ranging from 1.2 to 21.8 J g -1 and a Wigner energy accumulation rate of 1.9 × 10 -21 J g -1 n -1 m 2. The differential-scanning-calorimeter curves exhibit, in addition to the well known peak at ˜200 °C, a pronounced fine structure consisting of additional peaks at ˜150, ˜230, and ˜280 °C. These peaks correspond to activation energies of 1.31, 1.47, 1.57, and 1.72 eV, respectively. Crystal structure of the samples is intact. The dependence of the c lattice parameter on temperature between 25 and 725 °C as determined by Rietveld refinement leads to the expected microscopic thermal expansion coefficient along the c axis of ˜26 × 10 -6 °C -1. At 200 °C, coinciding with the maximum in the differential-scanning-calorimeter curves, no measurable changes in the rate of thermal expansion have been detected - unlike its decrease previously seen in more highly irradiated graphite.

  1. The system for diagnostics and monitoring of the IBR-2 reactor state. Data acquisition, accumulation, and storage the information

    Full text: Powerful pulsed neutron sources (PNS) containing hyperactive components of plutonium or uranium that are potentially dangerous for people and environment. That is why the development of reliable and effective systems for diagnostics of PNS is an urgent present-day task. This work's objective is development and construction the informative and diagnostic system located on the IBR-2 pulsed reactor operating in the Frank Laboratory of Neutron physics in Joint Institute of Nuclear Research (Dubna, Russia). The fact that each neutron pulsed source is a unique physical installation is important methodologically for this work. That influenced the choice of rather general concept of PNS measuring and diagnostic system development. The system is based on the principle of main parameters measurement, defining the PNS stability, reliability and safety, filtering the most informative features in noise, vibration and dynamic condition of PNS and further analysis of the factors that caused changes in certain defined features. Measuring systems of this kind, the systems of multi-parameter analysis using mutually complementary different diagnostic algorithms, can provide informative and diagnostic support of nearly any PNS type. The system includes a number of subsystems of 70 reactor parameters measuring and processing, including noise, technological, vibrational etc ones. The system basic concept is a three-level distributed real-time system consisting of a number of workstations and measuring subsystems. The standard PC-computers are used as the workstations. The measuring stations provide synchronized measurement of a number of reactor parameters (up to 70) of different nature with frequency sampling of 25, 5 and 1 Hz and their transfer to the operative data base. The main and operative data bases are set on the server. All the system users have access to this server through the Ethernet and WEB-server. The second-level workstation has the monitoring function, i

  2. Approaches to Accounting and Prediction of Fast Neutron Fluence on VVER Pressure Vessels for Estimation of RPV Residual Lifetime in Compliance with Russian Utility's Procedure

    Borodkin Gennady

    2016-01-01

    Full Text Available The Paper describes a new Russian Utility's regulatory document (RD EO which has been recently developed and implemented since the beginning of 2013. This RD EO includes the procedure of RPV FNF monitoring and provides recommendations on how to predict fluence over the design lifetime taking into account results of FNF monitoring. The basic method of RPV neutron fluence monitoring is neutron transport calculations of FR in the vicinity of the RPV. Reliability of the calculation results should be validated by ex-vessel neutron-activation measurements, which were performed during different fuel cycles with different core loadings including new types of fuel.

  3. Approaches to Accounting and Prediction of Fast Neutron Fluence on VVER Pressure Vessels for Estimation of RPV Residual Lifetime in Compliance with Russian Utility's Procedure

    Borodkin, Gennady; Borodkin, Pavel; Khrennikov, Nikolay; Ryabinin, Yuriy; Adeev, Valeriy

    2016-02-01

    The Paper describes a new Russian Utility's regulatory document (RD EO) which has been recently developed and implemented since the beginning of 2013. This RD EO includes the procedure of RPV FNF monitoring and provides recommendations on how to predict fluence over the design lifetime taking into account results of FNF monitoring. The basic method of RPV neutron fluence monitoring is neutron transport calculations of FR in the vicinity of the RPV. Reliability of the calculation results should be validated by ex-vessel neutron-activation measurements, which were performed during different fuel cycles with different core loadings including new types of fuel.

  4. Two benchmarks for qualification of pressure vessel fluence calculational methodology

    Two benchmarks for the qualification of the pressure vessel fluence calculational methodology were formulated and are briefly described. The Pool Critical Assembly (PCA) benchmark is based on the experiments performed at the PCA in Oak Ridge. The measured quantities to be compared against the calculated values are the equivalent fission fluxes at several locations in front, behind, and inside the pressure-vessel wall simulator. This benchmark is particularly suitable to test the capabilities of the calculational methodology and cross-section libraries to predict in-vessel gradients because only a few approximations are necessary in the analysis. The HBR-2 benchmark is based on the data for the H.B. Robinson-2 plant, which is a 2,300 MW (thermal) pressurized light-water reactor. The benchmark provides the reactor geometry, the material compositions, the core power distributions, and the power historical data. The quantities to be calculated are the specific activities of the radiometric monitors that were irradiated in the surveillance capsule and in the cavity location during one fuel cycle. The HBR-2 benchmark requires modeling approximations, power-to-neutron source conversion, and treatment of time dependant variations. It can therefore be used to test the overall performance and adequacy of the calculational methodology for power-reactor pressure-vessel flux calculations. Both benchmarks were analyzed with the DORT code and the BUGLE-96 cross-section library that is based on ENDF/B-VI evaluations. The calculations agreed with the measurements within 10%, and the calculations underpredicted the measurements in all the cases. This indicates that the ENDF/B-VI cross sections resolve most of the discrepancies between the measurements and calculations. The decrease of the CIM ratios with increased thickness of iron, which was typical for pre-ENDF/B-VI libraries, is almost completely removed

  5. Fluence scan: an unexplored property of a laser beam

    We present an extended theoretical background of so-called fluence scan (f-scan or F-scan) method, which is frequently being used for offline characterization of focused short-wavelength (EUV, soft X-ray, and hard X-ray) laser beams [J. Chalupsky et al., Opt. Express 18, 27836 (2010)]. The method exploits ablative imprints in various solids to visualize iso-fluence beam contours at different fluence and/or clip levels. An f-scan curve (clip level as a function of the corresponding iso-fluence contour area) can be generated for a general non-Gaussian beam. As shown in this paper, fluence scan encompasses important information about energy distribution within the beam profile, which may play an essential role in laser-matter interaction research employing intense non-ideal beams. Here we for the first time discuss fundamental properties of the f-scan function and its inverse counterpart (if-scan). Furthermore, we extensively elucidate how it is related to the effective beam area, energy distribution, and to the so called Liu's dependence [J.M. Liu, Opt. Lett. 7, 196 (1982)]. A new method of the effective area evaluation based on weighted inverse f-scan fit is introduced and applied to real data obtained at the SCSS (SPring-8 Compact SASE Source) facility. (authors)

  6. Spectral fluence of neutrons generated by radiotherapeutic Linacs

    Spectral fluences of neutrons generated in the heads of the radiotherapeutic linacs Varian Clinac 2100 C/D and Siemens ARTISTE were measured by means of the Bonner spheres spectrometer whose active detector of thermal neutrons was replaced by an activation detector, i.e. a tablet made of pure manganese. Measurements with different collimator settings reveal an interesting dependence of neutron fluence on the area defined by the collimator jaws. The determined neutron spectral fluences were used to derive ambient dose equivalent rate along the treatment coach. To clarify at which components of the linac neutrons are mainly created, the measurements were complemented with MCNPX calculations based on a realistic model of the Varian Clinac. (authors)

  7. Neutron Fluence in Antiproton Radiotherapy, Measurements and Simulations

    Introduction: A significant part of the secondary particle spectrum from antiproton annihilation consists of fast neutrons, which may contribute to a significant dose background found outside the primary beam. Materials and Methods: Using a polystyrene phantom as a moderator, we have performed absolute fluence measurements of the thermalized part of the fast neutron spectrum using Lithium-6 and -7 Fluoride TLD pairs. The results were compared with the Monte Carlo particle transport code FLUKA. Results: The experimental results are found to be in good agreement with simulations. The thermal neutron kerma resulting from the measured thermal neutron fluence is insignificant compared to the contribution from fast neutrons. Discussion: The secondary neutron fluences encountered in antiproton therapy are found to be similar to values calculated for pion treatment, however exact modeling under more realistic treatment scenarios is still required to quantitatively compare these treatment modalities.

  8. Fluence dependence of deuterium retention in oxidized SS-316

    Oya, Yasuhisa; Suzuki, Sachiko; Matsuyama, Masao; Hayashi, Takumi; Yamanishi, Toshihiko; Asakura, Yamato; Okuno, Kenji

    2011-10-01

    The ion fluence dependence of deuterium retention in SS-316 during oxidation at a temperature of 673 K was studied to evaluate the dynamics of deuterium retention in the oxide layer of SS-316. The correlation between the chemical state of stainless steel and deuterium retention was evaluated using XPS and TDS. It was found that the major deuterium desorption temperatures were located at around 660 K and 935 K, which correspond to the desorption of deuterium trapped as hydroxide. The deuterium retention increased with increasing deuterium ion fluence, since the deuterium retention as hydroxide increased significantly. However, retention saturated at an ion fluence of ˜2.5 × 10 21 D + m -2. The XPS result showed that FeOOD was formed on the surface, although pure Fe also remained in the oxide layer. These facts indicate the nature of the oxide layer have a key role in deuterium trapping behavior.

  9. Probability model for cumulative solar proton event fluences

    We have presented a new approach to obtain the cumulative solar proton event fluence distribution at a desired confidence level and for a given period of time. Compared to previous models, the main advantages of the current model are: it includes a broader proton energy range (> 1 to > 300 MeV); it includes more recent data; it is formulated with analytic expressions and is therefore simpler to update and work with; it is consistent with previous probabilistic models of worst case solar proton event fluences, and worst case peak fluxes, thus providing a more complete complement of tools for the spacecraft designer. (authors)

  10. Nickel Foil as Transmutation Detector for Neutron Fluence Measurements

    Klupák Vít

    2016-01-01

    Full Text Available Activation detectors are very often used for determination of the neutron fluence in reactor dosimetry. However, there are few disadvantages concerning these detectors; it is the demand of the knowledge of the irradiation history and a loss of information due to a radioactive decay in time. Transmutation detectors TMD could be a solution in this case. The transmutation detectors are materials in which stable or long-lived nuclides are produced by nuclear reactions with neutrons. From a measurement of concentration of these nuclides, neutron fluence can be evaluated regardless of the cooling time.

  11. Fast neutron fluence of the Hiroshima atomic bomb

    The fast neutron fluence of the Hiroshima atomic bomb was estimated by measuring radioactive nuclides produced by the fast neutron reaction in various materials. The early measurements were carried out for 32P. The new data obtained for 63Ni produced by the 63Cu(n, p)63Ni reaction were shown. The data for 63Ni were obtained by both the accelerator mass spectrometry and the low background beta-ray measurement. The data for the fast neutron fluence are consistent with the values calculated by a new Dosimetry System 2002 (DS02). (author)

  12. Nickel Foil as Transmutation Detector for Neutron Fluence Measurements

    Klupák, Vít; Viererbl, Ladislav; Lahodová, Zdena; Šoltés, Jaroslav; Tomandl, Ivo; Kudějová, Petra

    2016-02-01

    Activation detectors are very often used for determination of the neutron fluence in reactor dosimetry. However, there are few disadvantages concerning these detectors; it is the demand of the knowledge of the irradiation history and a loss of information due to a radioactive decay in time. Transmutation detectors TMD could be a solution in this case. The transmutation detectors are materials in which stable or long-lived nuclides are produced by nuclear reactions with neutrons. From a measurement of concentration of these nuclides, neutron fluence can be evaluated regardless of the cooling time.

  13. Fluxes and fluences of SEP events derived from SOLPENCO

    A. Aran

    2005-11-01

    Full Text Available We have developed aran04 a tool for rapid predictions of proton flux and fluence profiles observed during gradual solar energetic particle (SEP events and upstream of the associated traveling interplanetary shocks. This code, named SOLPENCO (for SOLar Particle ENgineering COde, contains a data base with a large set of interplanetary scenarios under which SEP events develop. These scenarios are basically defined by the solar longitude of the parent solar activity, ranging from E75 to W90, and by the position of the observer, located at 0.4 AU or at 1.0 AU, from the Sun. We are now analyzing the performance and reliability of SOLPENCO. We address here two features of SEP events especially relevant to space weather purposes: the peak flux and the fluence. We analyze how the peak flux and the fluence of the synthetic profiles generated by SOLPENCO vary as a function of the strength of the CME-driven shock, the heliolongitude of the solar parent activity and the particle energy considered. In particular, we comment on the dependence of the fluence on the radial distance of the observer (which does not follow an inverse square law, and we draw conclusions about the influence of the shock as a particle accelerator in terms of its evolving strength and the heliolongitude of the solar site where the SEP event originated.

  14. Low energy high-fluence nitrogen implantation into tool steel

    The layer saturated with fine precipitates of nitride Fe3N was obtained in high speed R6M5 type steel by means of high fluence low energy nitrogen implantation at temperature of 500 deg C. The presence of modified surface layer leads to improvement of wear-resistance and increasing the microhardness of the steel by a factor of 1.9

  15. Neutron fluence rate measurement using prompt gamma rays

    A gamma ray spectrometer, with a 3'' X 3'' NaI(Tl) detector, with a moderator sphere has been utilised to measure the neutron fluence rate, with this value the H*(10) was estimated. When a neutron is captured by the hydrogen-based moderator, a 2.22 MeV prompt gamma ray is produced. In a multichannel analyser the net area under the 2.22 MeV photopeak is proportional to the total neutron fluence rate. The features of this system were determined by a Monte Carlo study that includes 3-, 5- and 10-inches diameter, water and polyethylene moderators and a 239Pu-Be source. The prompt gamma response was extended to monoenergetic neutron sources. To verify the response, a 239Pu-Be source in combination with a 10'' polyethylene sphere having a gamma-ray spectrometer with NaI(Tl) was utilised to estimate the neutron fluence rate and the H*(10). These results were compared with neutron fluence rate and H*(10) obtained using a Bonner sphere spectrometer and with the H*(10) measured using a neutron rem-meter. (authors)

  16. Calculation of reactor pressure vessel fluence using TORT code

    TORT is employed for fast neutron fluence calculation at the reactor pressure vessel. KORI Unit 1 reactor at cycle 1 is modeled for this calculation. Three-dimensional cycle averaged assembly power distributions for KORI Unit 1 at cycle 1 are calculated by using the core physics code, NESTLE 5.0. The root mean square error is within 4.3% compared with NDR (Nuclear Design Report) for all burnup steps. The C/E (Calculated/Experimental) values for the in-vessel dosimeters distribute between 0.98 and 1.36. The most updated cross-section library, BUGLE-96 based on ENDF/B-VI is used for the neutron fluence calculation. The maximum fast neutron fluence calculated on reactor pressure vessel for KORI Unit 1 operated for 411.41 effective full power days is 1.784x1018n/cm2. The position of the maximum neutron fluence in RPV wall 1/4 T is nearby 60 cm below the midplane at zero degree

  17. Uncertainties in the Fluence Determination in the Surveillance Samples of VVER-440

    Konheiser Joerg

    2016-01-01

    Full Text Available The reactor pressure vessel (RPV represents one of the most important safety components in a nuclear power plant. Therefore, surveillance specimen (SS programs for the RPV material exist to deliver a reliable assessment of RPV residual lifetime. This report will present neutron fluence calculations for SS. These calculations were carried out by the codes TRAMO [1] and DORT [2]. This study was accompanied by ex-vessel neutron dosimetry experiments at Kola NPP. The main neutron activation monitoring reactions were 54Fe(n,p54Mn and 58Ni(n,p58Co. Good agreement was found between the deterministic and stochastic calculation results and between the calculations and the ex-vessel measurements. The different influences on the monitors were studied. In order to exclude the possible healing effects of the samples due to excessive temperatures, the heat release in the surveillance specimens was determined based on the calculated gamma fluences. Under comparatively realistic conditions, the heat increased by 6 K.

  18. Performance of core modifications to reduce the reactor pressure vessel fluence

    It's often discussed that nuclear power plants (NPP) are designed for an operation of 40 years equivalent to 32 full power years (FPY) assuming a load factor of 0.8. Such fixed plant life times are subjects of US operating licenses but not, as in most other countries, in the Federal Republic of Germany. Here the operating licenses are issued for an indefinite period. However, the German utilities are continuously upgrading their plants to attain a safety level that meets all current requirements. These upgrading measures also include the replacement of bigger components like e.g. the steam generator. The reactor pressure vessel (RPV), however, has a special status. Unlike most other components of a NPP which most likely will be exchanged during its service life a replacement or annealing treatment of the RPV certainly require more efforts to be economically justified. Thus the embrittlement of the RPV has an essential impact on the life time of a NPP. The end-of-life (EOL) RPV material toughness in essential depends on the steel quality and the accumulated neutron fluence. For a given NPP the reduction of the neutron flux at the inner surface of the RPV is the only way to limit its embrittlement. The resulting modifications for the core loadings in combination with the insertion of additional core components like steel elements are described and the impact on core performance and RPV fluence considered. (UK)

  19. Pressure Vessel Investigations of the Former Greifswald NPP: Fluence Calculations and Niobium Based Fluence Measurements

    Pressure vessel integrity assessment after long-term service irradiation is commonly based on surveillance program results. Nevertheless, only the investigation of RPV material from decommissioned NPPs enables the evaluation of the real toughness response. Such a chance is given now through the investigation of material from the former Greifswald NPP (VVER-440/230) to evaluate the material state of a standard RPV design and to assess the quality of prediction rules and assessment tools. The operation of the four Greifswald units was finished in 1991 after 12--15 years of operation. In autumn 2005 the first trepans (diameter 120 mm) were gained from the unit 1 of this NPP. Some details of the trepanning procedure will be given. The paper mainly deals with the retrospective dosimetry based on Niobium, which is a trace element of the RPV material. The reaction 93Nb(n,n')93mNb with an energy dependence highly correlated to radiation damage and a half life of the reaction product of 16.13 years is well suited for retrospective fast neutron dosimetry. Fluence calculations using the code TRAMO were based on pin-wise time dependent neutron sources and an updated nuclear data base (ENDF/B-VI release 8). The neutron spectra were determined at the trepan positions. The different loading schemes of unit 1 (standard and with 4 or 6 dummy assemblies) were taken into account. The calculated specific 93mNb activities for February, 2006 at the sample positions were determined to 16.3 Bq/μg Nb for sample 1, (0.1 cm distance from inner wall), and 4.0 Bq/μg Nb for sample 2 (11.5 cm distance from inner wall). Unfortunately, a second neutron reaction besides 93Nb(n,n') leading to 93mNb-activity is the reaction 92Mo(n,γ)93Mo. 93Mo decays by electron capture to 93mNb with a half life of 4000 years and a branching ratio br = 0.88. As (n,γ)-reactions are produced mainly by low energy neutrons, being less important for material damage, the 93mNb-activity generated through the Mo

  20. The activation method for determining neutron spectra and fluences

    3 mm thick foils of 4 and 17 mm in diameter were used for measurements. NaI scintillation detectors 45 mm in diameter by 50 mm thick and 40 mm in diameter by 1 mm thick, and a Ge-Li spectrometer of 53 cm3 in volume were used for gamma detection. A photopeak or a certain part of the integral spectrum was measured for each radionuclide. Computer code PIKAR was applied in automatic calculation of a simple gamma spectrum obtained using the semiconductor spectrometer. The FACT code was used for calculating foil activity. Codes SAND II and RFSP were used for neutron spectra unfolding. Ge-Li detector spectrometry was used for determining neutron fluence. Code FLUE was used for determining the mean value of neutron flux density and fluence. (J.P.)

  1. Fluence-based Dosimetry using Fluorescent Nuclear Track Detectors

    Klimpki, Grischa

    2014-01-01

    Carbon ion radiotherapy offers conformal dose coverage of deep-seated tumors and an enhanced radiobiological effectiveness compared to conventional photon treatment. Since the clinical outcome depends on both energy deposition and particle field composition, spectroscopic beam information is imperative for treatment planning and verification. Current fluence-based dosimeters have the potential to measure required quantities, but because of their size and electronic components, the majority of...

  2. Nickel Foil as Transmutation Detector for Neutron Fluence Measurements

    Klupák Vít; Viererbl Ladislav; Lahodová Zdena; Šoltés Jaroslav; Tomandl Ivo; Kudějová Petra

    2016-01-01

    Activation detectors are very often used for determination of the neutron fluence in reactor dosimetry. However, there are few disadvantages concerning these detectors; it is the demand of the knowledge of the irradiation history and a loss of information due to a radioactive decay in time. Transmutation detectors TMD could be a solution in this case. The transmutation detectors are materials in which stable or long-lived nuclides are produced by nuclear reactions with neutrons. From a measur...

  3. Fluence-to-effective dose conversion coefficients for muons

    Fluence-to-effective dose conversion coefficients have been computed for negative and positive muons through Monte Carlo simulations with the FLUKA code. Calculations have been performed for various geometrical conditions of irradiation of an hermaphrodite phantom, placed in a vacuum. The energy range investigated was 1 MeV to 10 TeV. The calculated results are presented and discussed. A graphical presentation of organ doses is also given. (Author)

  4. Nanosims measurements of solar wind Mg, Fe, and Cr fluences

    Wang, J.; Nittler, L. R.; Burnett, D. S.

    2007-01-01

    The chemical composition of the Sun provides the reference standard for a wide variety of astronomical, cosmochemical, and geochemical studies. To better determine the solar composition, the Genesis spacecraft collected solar wind at the L1 point in the space for 27 months prior to returning samples to Earth in September 2004. Prior ion probe analyses of Genesis samples have found discrepant results for the Mg and Fe solar wind fluences from different collector materials [1]...

  5. Reflectivity scaling with fluence in picosecond four-wave mixing

    An active-passive mode-locked Nd:YAG laser oscillator and amplifier were used to produce a pulse train of about fourteen pulses under a Gaussian envelope. Each pulse was split into pump and signal pulses and used in the usual geometry to obtain a phase-conjugate reflection. In pulse average reflectivity measurements, the integrated pulse train reflectivity was observed to depend linearly on the pulse train fluence. In a single-pulse measurements, reflectivities were obtained from fast photodiode traces of the probe and phase-conjugate reflection with scaling by pulse train energy measurements. The pulse reflectivities were potted against pump pulse fluence to produce a graph. From the linearity of the log-log plot, it is apparent that the reflectivity has a power dependence on the fluence given by the slope of the line, which is close to unity. Until now, analytical solutions have been obtained only if the pump fields were cw or the pulses were much longer than the length of the interaction medium. In the case of the authors' experiments, the interaction was well confined within the medium. To analyze these short-pulse experiments, they have reformulated the coupled equations and redefined proper boundary conditions. By transforming the coordinates of the equations to a pulse fuence coordinate, an analytic solution was obtained for pulses of arbitrary shape. The results showed that reflectivity is a monotonically increasing function of the pump fluence. Unlike the solutions in the cw regime, there is no oscillation condition which gives infinite reflectivity for finite input. The linear dependence was observed in both pulse train average and single-pulse experiments

  6. Sensitivity Analysis and Neutron Fluence Adjustment for VVER-1000 Rpv

    Belousov, S.; Ilieva, Kr.; Kirilova, D.

    2003-06-01

    Adjustment of the neutron fluence at the VVER-1000 RPV inner wall has been carried out. For the purpose of this adjustment the neutron flux response sensitivity to the main parameters of calculation uncertainty has been calculated. The obtained sensitivities, the parameters uncertainty and activity measurement data of iron, copper and niobium detectors positioned behind the RPV of Kozloduy NPP Unit 5 have been used in this adjustment.

  7. Fast approximate delivery of fluence maps: the VMAT case

    Balvert, Marleen

    2016-01-01

    In this article we provide a method to generate the trade-off between delivery time and fluence map matching quality for volumetric modulated arc therapy (VMAT). At the heart of our method lies a mathematical programming model that, for a given duration of delivery, optimizes leaf trajectories and dose rates such that the desired fluence map is reproduced as well as possible. This model was presented for the single map case in a companion paper (Fast approximate delivery of fluence maps: the single map case). The resulting large-scale, non-convex optimization problem was solved using a heuristic approach. The single-map approach cannot directly be applied to the full arc case due to the large increase in model size, the issue of allocating delivery times to each of the arc segments, and the fact that the ending leaf positions for one map will be the starting leaf positions for the next map. In this article the method proposed in \\cite{dm1} is extended to solve the full map treatment planning problem. We test ...

  8. Correlating Fast Fluence to dpa in Atypical Locations

    Drury Thomas H.

    2016-01-01

    Full Text Available Damage to a nuclear reactor's materials by high-energy neutrons causes changes in the ductility and fracture toughness of the materials. The reactor vessel and its associated piping's ability to withstand stress without brittle fracture are paramount to safety. Theoretically, the material damage is directly related to the displacements per atom (dpa via the residual defects from induced displacements. However in practice, the material damage is based on a correlation to the high-energy (E > 1.0 MeV neutron fluence. While the correlated approach is applicable when the material in question has experienced the same neutron spectrum as test specimens which were the basis of the correlation, this approach is not generically acceptable. Using Monte Carlo and discrete ordinates transport codes, the energy dependent neutron flux is determined throughout the reactor structures and the reactor vessel. Results from the models provide the dpa response in addition to the high-energy neutron flux. Ratios of dpa to fast fluence are calculated throughout the models. The comparisons show a constant ratio in the areas of historical concern and thus the validity of the correlated approach to these areas. In regions above and below the fuel however, the flux spectrum has changed significantly. The correlated relationship of material damage to fluence is not valid in these regions without adjustment. An adjustment mechanism is proposed.

  9. Monitor

    US Agency for International Development — A custom-built, dual-language (English and Spanish) system (http://www.monitor.net.co/) developed by DevTech that debuted in January 2011. It features a central PMP...

  10. Smart radiation monitors as per international standards

    In Nuclear Reactors and accelerators, a large number of radiation monitors, typically 50 or more networked Area gamma monitors and Neutron Monitors indicating ambient dose rate equivalent H(10) and Fluence are required for Health physics and radiation protection. ECIL has developed (with BARC support) and supplied various Monitors like Neutron REM Monitors (NRM100, NRM 200) to RRMD BARC, Area Gamma Monitor, Neutron Flux Monitor, to VECC for accelerator radiation safety and. Radiological protection cannot be assured without adhering to regulatory requirements and international standards relating to radiological protection instrumentation. NRM 200 has been developed as per guidelines mentioned in IEC 61005 complying with calibration requirements, EMC/EMI requirements, Statistical fluctuation in firmware, Environmental tests and seismic qualification. The NRM 100 is a Battery Powered portable version of the NRM200. The Instruments consist of BF3 Neutron Detector, mounted within the moderator and associated electronics consisting of Charge sensitive Pre-Amplifier and Amplifier circuit, Processing unit, Low Voltage Supply and High Voltage supply. The Dose Equivalent Rate is presented on Analog meter as well as on LCD in digital format. NRMs are featured to display Accumulated Dose, Settable Dose Equivalent Rate Alarm level, Isolated 4-20mA Current Output, and Isolated RS485 Communication. These Units are planned for accreditation at International labs also. (author)

  11. Lifetime Neutron Fluence Analysis of the Ringhals Unit 1 Boiling Water Reactor

    Kulesza Joel A.

    2016-01-01

    Full Text Available This paper describes a neutron fluence assessment considering the entire commercial operating history (35 cycles or ∼ 25 effective full power years of the Ringhals Unit 1 reactor pressure vessel beltline region. In this assessment, neutron (E >1.0 MeV fluence and iron atom displacement distributions were calculated on the moderator tank and reactor pressure vessel structures. To validate those calculations, five in-vessel surveillance chain dosimetry sets were evaluated as well as material samples taken from the upper core grid and wide range neutron monitor tubes to act as a form of retrospective dosimetry. During the analysis, it was recognized that delays in characterizing the retrospective dosimetry samples reduced the amount of reactions available to be counted and complicated the material composition determination. However, the comparisons between the surveillance chain dosimetry measurements (M and calculated (C results show similar and consistent results with the linear average M/C ratio of 1.13 which is in good agreement with the resultant least squares best estimate (BE/C ratios of 1.10 for both neutron (E >1.0 MeV flux and iron atom displacement rate.

  12. Lifetime Neutron Fluence Analysis of the Ringhals Unit 1 Boiling Water Reactor

    Kulesza, Joel A.; Roudén, Jenny; Green, Eva-Lena

    2016-02-01

    This paper describes a neutron fluence assessment considering the entire commercial operating history (35 cycles or ˜ 25 effective full power years) of the Ringhals Unit 1 reactor pressure vessel beltline region. In this assessment, neutron (E >1.0 MeV) fluence and iron atom displacement distributions were calculated on the moderator tank and reactor pressure vessel structures. To validate those calculations, five in-vessel surveillance chain dosimetry sets were evaluated as well as material samples taken from the upper core grid and wide range neutron monitor tubes to act as a form of retrospective dosimetry. During the analysis, it was recognized that delays in characterizing the retrospective dosimetry samples reduced the amount of reactions available to be counted and complicated the material composition determination. However, the comparisons between the surveillance chain dosimetry measurements (M) and calculated (C) results show similar and consistent results with the linear average M/C ratio of 1.13 which is in good agreement with the resultant least squares best estimate (BE)/C ratios of 1.10 for both neutron (E >1.0 MeV) flux and iron atom displacement rate.

  13. He+ ion irradiation-induced disordering in L10-FePd thin films: Ion fluence dependence

    Highly ordered, epitaxial, isotope-periodic [natFePd/57FePd] multilayers were prepared by molecular beam epitaxy and irradiated with 130 keV He+ ions to fluences of up to 1.49 x 1016 atoms cm-2. Electron microscopy showed a gradual accumulation of defects and disordering in irradiated samples. A significant decrease in the long-range order parameter was observed by X-ray diffraction analysis. However, the structural changes remained local, as nuclear resonant X-ray reflectometry confirmed that the isotope multilayer maintained good periodicity

  14. Effects of fluence and fluence rate of proton irradiation upon magnetism in Fe65Ni35 Invar alloy

    Curie temperature, TC, of the Fe-Ni Invar alloys increase due to irradiation with electron and some kinds of ions. In this study, proton irradiation effects upon magnetism in an Fe65Ni35 alloy have been investigated. It is found that the increment of TC, ∆TC, increases with increasing fluence. The magnetic hysteresis curve of the alloy was found to be unaffected by irradiation. Comparing ∆TC and the calculated energy transfer from the ions to the sample, it seemed that ∆TC was found to be related to the number of vacancies formed in nuclear collision events. In addition, ∆TC was influenced by the fluence rate, i.e., the deposited energy per unit time. - Highlights: • Proton irradiation effect on TC of Fe65Ni35 was investigated. • Increment of TC, ∆TC, was confirmed in ion passed through and stopped samples. • The relationships among ∆TC and the deposited energy and vacancies were discussed. • It was reasonable to consider that ∆TC was related to the number of vacancies. • ∆TC was influenced by fluence rate, i.e. the energy deposition rate

  15. Monitoring

    Ložek, Vojen; Němec, J.

    Praha : Consult, 2003 - (Němec, J.), s. 111-115 ISBN 80-902132-4-3 Grant ostatní: Magistrát hlavního města Prahy(CZ) DAG/67/04/000176/2001 Institutional research plan: CEZ:AV0Z3013912 Keywords : monitoring * environmental quality * Prague Subject RIV: DB - Geology ; Mineralogy

  16. Monitoring

    ... its main source of fuel. To keep your blood sugar level on target and avoid problems with your eyes, kidneys, heart and feet, you should eat right ... better. And monitoring doesn’t stop at measuring blood sugar levels. Because ... blood testing) Eye health (eye exams) Foot health (foot exams and ...

  17. Fluence measurements applied to 5-20 MeV/amu ion beam dosimetry by simultaneous use of a total-absorption calorimeter and a Faraday cup

    A Faraday cup was fabricated for measuring the beam current of a few tens MeV/amu ion beams of the TIARA AVF cyclotron. It has been applied as a beam monitor for studying the characteristics of film dosimeters that are well-established for high doses of 60Co γ-rays and 1 to 10 MeV electrons. A total absorption calorimeter designed to measure energy fluence has also been tested for estimating the uncertainty in fluence measurement of 5-20 MeV/amu ion beams, by simultaneous use of the calorimeter and the Faraday cup in a broad uniform fluence field. The estimated fluence was evaluated on the basis of nominal particle energy values derived from the cyclotron acceleration parameters. The average ratio of the measured fluence values to the estimated values is 1.024, and the average precision is within ±2% at a 68% confidence level, for most of the ion beams with a range of kinetic energy per nucleon, 5-20 MeV/amu, at an integrated charge above 5 nC/cm2

  18. Fluence measurements applied to 5-20 MeV/amu ion beam dosimetry by simultaneous use of a total-absorption calorimeter and a Faraday cup

    Kojima, T; Takizawa, H; Tachibana, H; Tanaka, R

    1998-01-01

    A Faraday cup was fabricated for measuring the beam current of a few tens MeV/amu ion beams of the TIARA AVF cyclotron. It has been applied as a beam monitor for studying the characteristics of film dosimeters that are well-established for high doses of sup 6 sup 0 Co gamma-rays and 1 to 10 MeV electrons. A total absorption calorimeter designed to measure energy fluence has also been tested for estimating the uncertainty in fluence measurement of 5-20 MeV/amu ion beams, by simultaneous use of the calorimeter and the Faraday cup in a broad uniform fluence field. The estimated fluence was evaluated on the basis of nominal particle energy values derived from the cyclotron acceleration parameters. The average ratio of the measured fluence values to the estimated values is 1.024, and the average precision is within +-2% at a 68% confidence level, for most of the ion beams with a range of kinetic energy per nucleon, 5-20 MeV/amu, at an integrated charge above 5 nC/cm sup 2.

  19. Neutron flux and fluence determination for BWR reactors

    Measurements of gamma emission rates from Fe and Cu dosimeters extracted from a BWR type reactor vessel were carried out in order to determine their total activity. The dosimeter's activity is related to the neutron flux there by taking into account the reactor material's embrittlement caused by neutron bombardment. The dosimeters were taken out after the first reactor operation cycle. From gamma radioactivity measurements of these dosimeters, neutron flux and fluence were calculated. These parameters are used in the determination of shift and adjusted reference temperature values needed for the development of pressure-temperature curves used during reactor operation

  20. Neutron fluence in antiproton radiotherapy, measurements and simulations

    Bassler, Niels; Holzscheiter, Michael H.; Petersen, Jørgen B.B.

    2010-01-01

    part of the fast neutron spectrum using Lithium-6 and -7 Fluoride TLD pairs. The experimental results are found to be in good agreement with simulations using the Monte Carlo particle transport code FLUKA. The thermal neutron kerma resulting from the measured thermal neutron fluence is insignificant...... compared to the contribution from fast neutrons. The results are found to be similar to values calculated for pion treatment, however exact modeling under more realistic treatment scenarios is still required to quantitatively compare these treatment modalities....

  1. Towards a reference numerical scheme using MCNPX for PWR control rod tip fluence estimations

    Recent occurrences of cracks and fissures on the cladding tubes of PWR control rod (CR) fingers employed in the Swiss reactors prompted the need to develop more reliable analytical methods for CR tip fluence estimations. To partly address this need, a deterministic methodology based on SIMULATE-3/CASMO-4 was in recent years developed at PSI. Although this methodology has already been applied for independent support to licensing issues related to CR lifetime, two main questions are currently being the center of attention for further enhancements. First, the methodology relies on several assumptions that have so far not been verified. Secondly, an assessment of the achieved accuracy has not been addressed. In an attempt to answer both these open questions, it was considered appropriate to develop an alternative computational scheme based on the stochastic MCNPX code with the objective to provide reference numerical solutions. This paper presents the first steps undertaken in that direction. To start, a methodology for a volumetric neutron source transfer to full core MCNPX models with detailed CR as well as axial reflector representations is established. On this basis, the assumptions of the deterministic methodology are studied for selected CR configurations for two Beginning-of-Life cores by comparing the spatial neutron flux distributions obtained with the two approaches for the entire spectrum. Finally, for the high-energy range (E> 1 MeV) and for a few CRs, the new MCNPX scheme is applied to estimate the accumulated fluence over one real operated cycle and the results are compared with the deterministic approach. (authors)

  2. Absorbed dose evaluation by SISCODES code, kerma and fluence deviations

    Radiotherapy is a common treatment of cancer. Radiotherapy exposes the patient to a radiation field, producing ionization, and absorbed dose. A precise dose calculation and the ability to execute the irradiation on the patient are necessary in order to avoid serious injuries on the surrounding health tissue, thus, the maximum acceptable absorbed dose error from the prescribed and applied is about 5%. The doses on radiotherapy are usually calculated by superimposition experimental dose profile, namely PDP, which is experimentally measured in a water simulator. Moreover, the radiation interaction with human body tissues depends on the chemical composition and the tissue density, which means the anthropomorphism and anthropometric of the human being. This paper evaluates the deviation of calculated value of kerma, induced by human body heterogeneities. To do this job two thorax voxel models created on SISCODES (one filled with various tissues other filled with water) were applied. The result of simulations permits two different comparisons. One is the ratio between tissues kermas and water kerma. Another is the ratio between human phantom fluence, where exists radiation scatter and reflection, and water phantom fluence. The reconstructed pictures of studied regions showing the calculated ratios, and graphs of the ratios versus energy of each tissue are shown. The dose ratio deviations obtained are, in some situations, larger than the acceptable 5% point out serious miscalculation of doses for some spatial regions on the human body. (author)

  3. Survivor dosimetry. Part A. Fluence-to-kerma conversion coefficients

    An important step in the dosimetry evaluation is to relate the radiation passing through a unit volume of a material of interest (fluence) to the energy release (kerma) in the material, which determines the absorbed dose. The fluence-to-kerma conversion coefficients or 'kerma coefficients' used in the Dosimetry System 1986 (DS86) are taken from Kerr (1982). These kerma coefficients are based on body tissue compositions for Reference Man from the International Commission on Radiological Protection (1975) and Kerr (1982), the mass energy-absorption coefficients for photons from Hubbell (1982), and the elemental kerma coefficients for neutrons from Caswell et al. (1980). Hence, the kerma coefficients used in DS86 are approximately 20 years old. In order to provide an updated set of kerma coefficients for use in the Dosimetry System 2002 (DS02), a new evaluation has been completed. This new evaluation considered recently suggested changes in the composition of soft tissues of the body in ICRU Report 44 (International Commission on Radiation Units and Measurements 1989), the mass energy-absorption coefficients for photons by Hubbell and Seltzer (1996), and the elemental kerma coefficients for neutrons in ICRU Report 63 (International Commission on Radiation Units and Measurements 2000). The new DS02 kerma coefficients for soft tissue are presented as both point-wise data for use in Monte Carlo radiation transport calculations and multigroup data for use in discrete ordinates radiation transport calculations. (author)

  4. Design of new irradiation capsules for controlling temperature and fluence

    Choo, K. N.; Choi, M. H.; Cho, M. S.; Shin, Y. T.; Kim, B. G. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2004-07-01

    Various irradiation devices have been developed at HANARO (High flux Advanced Neutron Application ReactOr). Among the irradiation facilities, a capsule is the most useful device to cope with various test requirements. Instrumented and non-instrumented capsules have been developed at HANARO for new alloy and fuel developments and the life time estimation of nuclear power plants. Extensive efforts have been made to establish design and manufacturing technology for the capsule and temperature control system, which should be compatible with HANARO's characteristics. 9 instrumented and 2 non-instrumented capsules were designed, fabricated and successfully irradiated since the first non-instrumented capsule (96M-01K) for various materials irradiation. In an irradiation test using a research reactor, temperature and fluence are mainly dependent of reactor operation condition such as reactor power mode and operation time. In consequence, the irradiated specimen is subjected to the change of temperature as well as of neutron flux during reactor power transient such as start-up and shut-down. A large difference in the defect structure has been reported to be caused by this transient irradiation from the mechanism of the defect structure development. Therefore, the development of new capsule technology has been required to overcome those limitations. In this paper, current status of development of the capsule for controlling temperature and fluence in HANARO is described.

  5. Design of new irradiation capsules for controlling temperature and fluence

    Various irradiation devices have been developed at HANARO (High flux Advanced Neutron Application ReactOr). Among the irradiation facilities, a capsule is the most useful device to cope with various test requirements. Instrumented and non-instrumented capsules have been developed at HANARO for new alloy and fuel developments and the life time estimation of nuclear power plants. Extensive efforts have been made to establish design and manufacturing technology for the capsule and temperature control system, which should be compatible with HANARO's characteristics. 9 instrumented and 2 non-instrumented capsules were designed, fabricated and successfully irradiated since the first non-instrumented capsule (96M-01K) for various materials irradiation. In an irradiation test using a research reactor, temperature and fluence are mainly dependent of reactor operation condition such as reactor power mode and operation time. In consequence, the irradiated specimen is subjected to the change of temperature as well as of neutron flux during reactor power transient such as start-up and shut-down. A large difference in the defect structure has been reported to be caused by this transient irradiation from the mechanism of the defect structure development. Therefore, the development of new capsule technology has been required to overcome those limitations. In this paper, current status of development of the capsule for controlling temperature and fluence in HANARO is described

  6. DS02 fluence spectra for neutrons and gamma rays at Hiroshima and Nagasaki with fluence-to-kerma coefficients and transmission factors for sample measurements.

    Egbert, Stephen D; Kerr, George D; Cullings, Harry M

    2007-11-01

    Fluence spectra at several ground distances in Hiroshima and Nagasaki are provided along with associated fluence-to-kerma coefficients from the Dosimetry System 2002 (DS02). Also included are transmission factors for calculating expected responses of in situ sample measurements of neutron activation products such as (32)P,(36)Cl,(39)Ar,(41)Ca, (60)Co,(63)Ni,(152)Eu, and (154)Eu. The free-in-air (FIA) fluences calculated in 2002 are available for 240 angles, 69 energy groups, 101 ground distances, 5 heights, 4 radiation source components, 2 cities. The DS02 code uses these fluences partitioned to a prompt and delayed portion, collapsed to 58 energy groups and restricted to 97 ground distances. This is because the fluence spectra were required to be in the same format that was used in the older Dosimetry System 1986 (DS86) computer code, of which the DS02 computer code is a modification. The 2002 calculation fluences and the collapsed DS02 code fluences are presented and briefly discussed. A report on DS02, which is available on the website at the Radiation Effects Research Foundation, provides tables and figures of the A-bomb neutron and gamma-ray output used as the sources in the 2002 radiation transport calculations. While figures illustrating the fluence spectra at several ground ranges are presented in the DS02 Report, it does not include any tables of the calculated fluence spectra in the DS02 report. This paper provides, at several standard distances from the hypocenter, the numerical information which is required to translate the FIA neutron fluences given in DS02 to a neutron activation measurement or neutron and gamma-ray soft-tissue dose. PMID:17643260

  7. Determining the incident electron fluence for Monte Carlo-based photon treatment planning using a standard measured data set

    An accurate dose calculation in phantom and patient geometries requires an accurate description of the radiation source. Errors in the radiation source description are propagated through the dose calculation. With the emergence of linear accelerators whose dosimetric characteristics are similar to within measurement uncertainty, the same radiation source description can be used as the input to dose calculation for treatment planning at many institutions with the same linear accelerator model. Our goal in the current research was to determine the initial electron fluence above the linear accelerator target for such an accelerator to allow a dose calculation in water to within 1% or 1 mm of the measured data supplied by the manufacturer. The method used for both the radiation source description and the patient transport was Monte Carlo. The linac geometry was input into the Monte Carlo code using the accelerator's manufacturer's specifications. Assumptions about the initial electron source above the target were made based on previous studies. The free parameters derived for the calculations were the mean energy and radial Gaussian width of the initial electron fluence and the target density. A combination of the free parameters yielded an initial electron fluence that, when transported through the linear accelerator and into the phantom, allowed a dose-calculation agreement to the experimental ion chamber data to within the specified criteria at both 6 and 18 MV nominal beam energies, except near the surface, particularly for the 18 MV beam. To save time during Monte Carlo treatment planning, the initial electron fluence was transported through part of the treatment head to a plane between the monitor chambers and the jaws and saved as phase-space files. These files are used for clinical Monte Carlo-based treatment planning and are freely available from the authors

  8. MU Fluence Reconstruction based-on Delivered Leaf Position: for IMRT Quality Assurance

    The measurement-based verification for intensity modulated radiation therapy (IMRT) is a time-and labor-consuming procedure. Instead, this study aims to develop a MU fluence reconstruction method for IMRT QA. Total actual fluences from treatment planning system (TPS, Eclipse 8.6, Varian) were selected as a reference. Delivered leaf positions according to MU were extracted by the dynalog file generated after IMRT delivery. An in-house software was develop to reconstruct MU fluence from the acquired delivered leaf position data using MATLAB. We investigated five patient's plans delivered by both step-and-shoot IMRT and sliding window technologies. The total actual fluence was compared with the MU fluence reconstructed by using commercial software (Verisoft 3.1, PTW) and gamma analysis method (criteria: 3%/3 mm and 2%/1 mm). Gamma pass rates were 91.8±1.33% and the reconstructed fluence was shown good agreement with RTP-based actual fluence. The fluence from step and shoot IMRT was shown slightly higher agreement with the actual fluence than that from sliding window IMRT. If moving from IMRT QA measurements toward independent computer calculations, the developed method can be used for IMRT QA. A point dose calculation method from reconstructed fluences is under development for the routine IMRT QA purpose

  9. The fluence threshold of femtosecond laser blackening of metals: The effect of laser-induced ripples

    Ou, Zhigui; Huang, Min; Zhao, Fuli

    2016-05-01

    With the primary controlling factor of the laser fluence, we have investigated femtosecond laser blackening of stainless steel, brass, and aluminum in visible light range. In general, low reflectance about 5% can be achieved in appropriate ranges of laser fluences for all the treated metal surfaces. Significantly, towards stainless steel and brass a fluence threshold of blackening emerges unusually: a dramatic reflectance decline occurs in a specific, narrow fluence range. In contrast, towards aluminum the reflectance declines steadily over a wide fluence range instead of the threshold-like behavior from steel and brass. The morphological characteristics and corresponding reflectance spectra of the treated surfaces indicates that the blackening threshold of stainless steel and brass corresponds to the fluence threshold of laser-induced subwavelength ripples. Such periodic ripples growing rapidly near ablation threshold absorb visible light efficiently through grating coupling and cavity trapping promoted by surface plasmon polaritons. Whereas, for aluminum, with fluence increasing the looming ripples are greatly suppressed by re-deposited nanoparticle aggregates that present intrinsic colors other than black, and until the formation of large scale "ravines" provided with strong light-trapping, sufficient blackening is achieved. In short, there are different fluence dependencies for femtosecond laser blackening of metals, and the specific blackening fluence threshold for certain metals in the visible range originates in the definite fluence threshold of femtosecond laser-induced ripples.

  10. A simple and rapid HPLC-DAD method for simultaneously monitoring the accumulation of alkaloids and precursors in different parts and different developmental stages of Catharanthus roseus plants.

    Pan, Qifang; Saiman, Mohd Zuwairi; Mustafa, Natali Rianika; Verpoorte, Robert; Tang, Kexuan

    2016-03-01

    A rapid and simple reversed phase liquid chromatographic system has been developed for simultaneous analysis of terpenoid indole alkaloids (TIAs) and their precursors. This method allowed separation of 11 compounds consisting of eight TIAs (ajmalicine, serpentine, catharanthine, vindoline, vindolinine, vincristine, vinblastine, and anhydrovinblastine) and three related precursors i.e., tryptophan, tryptamine and loganin. The system has been applied for screening the TIAs and precursors in Catharanthus roseus plant extracts. In this study, different organs i.e., flowers, leaves, stems, and roots of C. roseus were investigated. The results indicate that TIAs and precursor accumulation varies qualitatively and quantitatively in different organs of C. roseus. The precursors showed much lower levels than TIAs in all organs. Leaves and flowers accumulate higher level of vindoline, catharanthine and anhydrovinblastine while roots have higher level of ajmalicine, vindolinine and serpentine. Moreover, the alkaloid profiles of leaves harvested at different ages and different growth stages were studied. The results show that the levels of monoindole alkaloids decreased while bisindole alkaloids increased with leaf aging and upon plant growth. The HPLC method has been successfully applied to detect TIAs and precursors in different types of C. roseus samples to facilitate further study of the TIA pathway and its regulation in C. roseus plants. PMID:26854826

  11. Moss monitoring as a mirror of land use? Nitrogen and metal accumulation in mosses of two regions in middle Europe; Moosmonitoring als Spiegel der Landnutzung? Stickstoff- und Metallakkumulation in Moosen zweier Regionen Mitteleuropas

    Schroeder, W.; Hornsmann, I.; Pesch, R.; Schmidt, G. [Hochschule Vechta (Germany). Lehrstuhl fuer Landschaftsoekologie; Fraenzle, S.; Wuenschmann, S.; Heidenreich, H.; Markert, B. [Internationales Hochschulinstitut, Zittau (Germany)

    2008-02-15

    Goal, Scope and Background. The study was conducted to test the hypothesis that the regional variability of nitrogen (N) and metal accumulations in terrestrial ecosystems are due to historical and recent ways of land use. To this end, in two regions of Central Europe the metal and N accumulations in both regions should be examined by comparative moss analysis. The regions should be of quantitatively specified representativity for selected ecological characteristics of Europe. Within both regions these characteristics should be covered by the sites where the moss samples were collected. The number of samples should allow for geostatistical estimation of the measured nitrogen and metal loads. Results. By use of the ecological regionalisation of Europe the Weser-Ems Region (WER) and the Euro Region Nissa (ERN) were selected for investigation. The sampling sites represent quite well the natural landscapes and the land use categories of both regions. The measurement values corroborate the decline of metal accumulation observed since the beginning of the European Mosses Monitoring Survey in 1990. The metal loads of the mosses in the ERN exceed those in the WER significantly. The opposite holds true for the N concentrations: those in the WER are significantly higher than those in the ERN. (orig.)

  12. A virtual photon energy fluence model for Monte Carlo dose calculation

    The presented virtual energy fluence (VEF) model of the patient-independent part of the medical linear accelerator heads, consists of two Gaussian-shaped photon sources and one uniform electron source. The planar photon sources are located close to the bremsstrahlung target (primary source) and to the flattening filter (secondary source), respectively. The electron contamination source is located in the plane defining the lower end of the filter. The standard deviations or widths and the relative weights of each source are free parameters. Five other parameters correct for fluence variations, i.e., the horn or central depression effect. If these parameters and the field widths in the X and Y directions are given, the corresponding energy fluence distribution can be calculated analytically and compared to measured dose distributions in air. This provides a method of fitting the free parameters using the measurements for various square and rectangular fields and a fixed number of monitor units. The next step in generating the whole set of base data is to calculate monoenergetic central axis depth dose distributions in water which are used to derive the energy spectrum by deconvolving the measured depth dose curves. This spectrum is also corrected to take the off-axis softening into account. The VEF model is implemented together with geometry modules for the patient specific part of the treatment head (jaws, multileaf collimator) into the XVMC dose calculation engine. The implementation into other Monte Carlo codes is possible based on the information in this paper. Experiments are performed to verify the model by comparing measured and calculated dose distributions and output factors in water. It is demonstrated that open photon beams of linear accelerators from two different vendors are accurately simulated using the VEF model. The commissioning procedure of the VEF model is clinically feasible because it is based on standard measurements in air and water. It is

  13. Constant-Fluence Area Scaling for Laser Propulsion

    A series of experiments was conducted on polyoxymethylene (POM, trade name Delrin registered ) propellants in air at atmospheric pressure. A TEA CO2 laser with maximum output power up to 20 J was used to deliver 300 ns pulses of 10.6 μm radiation to POM targets. Ablation at a constant fluence and a range of spot areas was achieved by varying combinations of the laser energy and spot size. Relevant empirical scaling laws governing laser propulsion parameters such as the momentum coupling coefficient (Cm) and specific impulse (Isp) for spot areas within a range of about 0.05-0.25 cm2 are presented. Experimental measurements of imparted impulse, Cm, Isp, and ablated mass per pulse were made using dynamic piezoelectric force sensors and a scientific balance. Finally, Schlieren ICCD imaging of shock waves and vapor plumes was performed and analyzed

  14. Effect of fluence smoothing on the quality of intensity-modulated radiation treatment plans.

    Niyas, Puzhakkal; Abdullah, Kallikuzhiyil Kochunny; Noufal, Manthala Padannayil; Sankaran Nair, Thekkedath

    2016-07-01

    A fluence-smoothing function applied for reducing the complexity of a treatment plan is an optional requirement in the inverse planning optimization algorithm of intensity-modulated radiation therapy (IMRT). In this study, we investigated the consequences of fluence smoothing on the quality of highly complex and inhomogeneous plans in a treatment-planning system, Eclipse™. The smoothing function was applied both in the direction of leaf travel (X) and perpendicular to leaf travel (Y). Twenty IMRT plans from patients with cancer of the nasopharynx and lung were selected and re-optimized with use of various smoothing combinations from X = 0, Y = 0 to X = 100, Y = 100. Total monitor units (MUs), dose-volume histograms, and radiobiological estimates were computed for all plans. The study yielded a significant reduction in the average total MUs from 2079 ± 265.4 to 1107 ± 137.4 (nasopharynx) and from 1556 ± 490.3 to 791 ± 176.8 (lung) while increasing smoothing from X, Y = 0 to X, Y = 100. Both the tumor control and normal tissue complication probabilities were found to vary, but not significantly so. No appreciable differences in doses to the target and most of the organs at risk (OARs) were noticed. The doses measured with the I'MRT MatriXX 2-D system indicated improvements in deliverability of the plans with higher smoothing values. Hence, it can be concluded that increased smoothing reduced the total MUs exceptionally well without any considerable changes in OAR doses. The observed progress in plan deliverability in terms of the gamma index strongly supports the recommendation of smoothing levels up to X = 70 and Y = 60, at least for the nasopharynx and lung. PMID:26951466

  15. Radiochemical estimation of neutron fluence of Hiroshima and Nagasaki atomic bombs

    Purpose: To estimate neutron fluence of Hiroshima and Nagasaki atomic bombs by radiochemical methods. Methods: Thermal neutron fluence at the time of explosion was estimated from the results of radiochemical analysis of residual 60Co in iron materials or iron products. Results: Materials were obtained through the kindness of Dr. Masanori Nakaidzum. The distribution of neutron fluence in Hiroshima and Nagasaki can be determined by measuring the residual radioactivity of many pieces of material by radiochemical methods presented in the paper

  16. Fractal characterization of the silicon surfaces produced by ion beam irradiation of varying fluences

    Yadav, R.P. [Department of Physics, University of Allahabad, Allahabad, UP 211002 (India); Kumar, T. [Department of Physics, Central University of Haryana, Jant-Pali, Mahendergarh, Haryana 123029 (India); Mittal, A.K. [Department of Physics, University of Allahabad, Allahabad, UP 211002 (India); K Banerjee Centre of Atmospheric and Ocean Studies, University of Allahabad, Allahabad, UP 211002 (India); Dwivedi, S., E-mail: suneetdwivedi@gmail.com [K Banerjee Centre of Atmospheric and Ocean Studies, University of Allahabad, Allahabad, UP 211002 (India); Kanjilal, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, PO Box 10502, New Delhi 110 067 (India)

    2015-08-30

    Highlights: • Fractal analysis of Si(1 0 0) surface morphology at varying ion fluences. • Autocorrelation function and height–height correlation function as fractal measures. • Surface roughness and lateral correlation length increases with ion fluence. • Ripple pattern of the surfaces is found at higher ion fluences. • Wavelength of the ripple surfaces is computed for each fluence. - Abstract: Si (1 0 0) is bombarded with 200 keV Ar{sup +} ion beam at oblique incidence with fluences ranging from 3 × 10{sup 17} ions/cm{sup 2} to 3 × 10{sup 18} ions/cm{sup 2}. The surface morphology of the irradiated surfaces is captured by the atomic force microscopy (AFM) for each ion fluence. The fractal analysis is performed on the AFM images. The autocorrelation function and height–height correlation function are used as fractal measures. It is found that the average roughness, interface width, lateral correlation length as well as roughness exponent increase with ions fluence. The analysis reveals the ripple pattern of the surfaces at higher fluences. The wavelength of the ripple surfaces is computed for each ion fluence.

  17. Fractal characterization of the silicon surfaces produced by ion beam irradiation of varying fluences

    Highlights: • Fractal analysis of Si(1 0 0) surface morphology at varying ion fluences. • Autocorrelation function and height–height correlation function as fractal measures. • Surface roughness and lateral correlation length increases with ion fluence. • Ripple pattern of the surfaces is found at higher ion fluences. • Wavelength of the ripple surfaces is computed for each fluence. - Abstract: Si (1 0 0) is bombarded with 200 keV Ar+ ion beam at oblique incidence with fluences ranging from 3 × 1017 ions/cm2 to 3 × 1018 ions/cm2. The surface morphology of the irradiated surfaces is captured by the atomic force microscopy (AFM) for each ion fluence. The fractal analysis is performed on the AFM images. The autocorrelation function and height–height correlation function are used as fractal measures. It is found that the average roughness, interface width, lateral correlation length as well as roughness exponent increase with ions fluence. The analysis reveals the ripple pattern of the surfaces at higher fluences. The wavelength of the ripple surfaces is computed for each ion fluence

  18. Fluorescence spectra of Rhodamine 6G for high fluence excitation laser radiation

    Hung, J; Olaizola, A M

    2003-01-01

    Fluorescence spectral changes of Rhodamine 6G in ethanol and glycerol solutions and deposited as a film on a silica surface have been studied using a wide range of pumping field fluence at 532 nm at room temperature. Blue shift of the fluorescence spectra and fluorescence quenching of the dye molecule in solution are observed at high excitation fluence values. Such effects are not reported for the film sample. The effects are interpreted as the result of population redistribution in the solute-solvent molecular system induced by the high fluence field and the fluence dependence of the radiationless decay mechanism.

  19. Heavy Ion Irradiation Fluence Dependence for Single-Event Upsets of NAND Flash Memory

    Chen, Dakai; Wilcox, Edward; Ladbury, Raymond; Kim, Hak; Phan, Anthony; Seidleck, Christina; LaBel, Kenneth

    2016-01-01

    We investigated the single-event effect (SEE) susceptibility of the Micron 16 nm NAND flash, and found the single-event upset (SEU) cross section varied inversely with fluence. The SEU cross section decreased with increasing fluence. We attribute the effect to the variable upset sensitivities of the memory cells. The current test standards and procedures assume that SEU follow a Poisson process and do not take into account the variability in the error rate with fluence. Therefore, heavy ion irradiation of devices with variable upset sensitivity distribution using typical fluence levels may underestimate the cross section and on-orbit event rate.

  20. Evaluation of damage accumulation behavior and strength anisotropy of NITE SiC/SiC composites by acoustic emission, digital image correlation and electrical resistivity monitoring

    Nozawa, Takashi; Ozawa, Kazumi; Asakura, Yuuki; Kohyama, Akira; Tanigawa, Hiroyasu

    2014-12-01

    Understanding the cracking process of the composites is essential to establish the design basis for practical applications. This study aims to investigate the damage accumulation process and its anisotropy for nano-infiltration transient eutectic sintered (NITE) SiC/SiC composites by various characterization techniques such as the acoustic emission (AE), digital image correlation (DIC) and electrical resistivity (ER) measurements. Cracking behavior below the proportional limit stress (PLS) was specifically addressed. Similar to the other generic SiC/SiC composites, the 1st AE event was identified below the PLS for NITE SiC/SiC composites with a dependency of fabric orientation. The DIC results support that the primary failure mode depending on fiber orientation affected more than the other minor modes did. Detailed AE waveform analysis by wavelet shows a potential to classify the failure behavior depending on architecture. Cracking below the PLS is a potential concern in component deign but the preliminary ER measurements imply that the impact of cracking below the PLS on composite function was limited.

  1. Accumulation of color centers in lithium fluoride crystals under irradiation with swift lead projectiles

    Lithium fluoride crystals were irradiated with lead ions of different energies, having the electronic energy loss of 10–20 keV/nm. Accumulation of F centers with fluence was studied by absorption UV–VIS spectroscopy. It was found that the average F-center concentration is mainly determined by the average absorbed energy density with a weak decrease above 1023 eV/cm3. A defect accumulation model, taking into account the recombination processes, is proposed for a seamless description of the F-center concentration fluence dependences for various projectiles and energy losses

  2. Accumulation of color centers in lithium fluoride crystals under irradiation with swift lead projectiles

    Benhacine, H. [LRPCSI, University of 20 Août 1955 Skikda, Route El-Hadaeik, 21000 Skikda (Algeria); Département de physique Université Constantine 1, Route Ain El-Bey 25000 (Algeria); Sorokin, M.V., E-mail: m40@lab2.ru [National Research Centre ‘Kurchatov Institute’, Kurchatov Square 1, 123182 Moscow (Russian Federation); Schwartz, K. [GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany); Meftah, A. [LRPCSI, University of 20 Août 1955 Skikda, Route El-Hadaeik, 21000 Skikda (Algeria)

    2015-09-15

    Lithium fluoride crystals were irradiated with lead ions of different energies, having the electronic energy loss of 10–20 keV/nm. Accumulation of F centers with fluence was studied by absorption UV–VIS spectroscopy. It was found that the average F-center concentration is mainly determined by the average absorbed energy density with a weak decrease above 10{sup 23} eV/cm{sup 3}. A defect accumulation model, taking into account the recombination processes, is proposed for a seamless description of the F-center concentration fluence dependences for various projectiles and energy losses.

  3. High-fluence Ga-implanted silicon—The effect of annealing and cover layers

    The influence of SiO2 and SiNx cover layers on the dopant distribution as well as microstructure of high fluence Ga implanted Si after thermal processing is investigated. The annealing temperature determines the layer microstructure and the cover layers influence the obtained Ga profile. Rapid thermal annealing at temperatures up to 750 °C leads to a polycrystalline layer structure containing amorphous Ga-rich precipitates. Already after a short 20 ms flash lamp annealing, a Ga-rich interface layer is observed for implantation through the cover layers. This effect can partly be suppressed by annealing temperatures of at least 900 °C. However, in this case, Ga accumulates in larger, cone-like precipitates without disturbing the surrounding Si lattice parameters. Such a Ga-rich crystalline Si phase does not exist in the equilibrium phase diagram according to which the Ga solubility in Si is less than 0.1 at. %. The Ga-rich areas are capped with SiOx grown during annealing which only can be avoided by the usage of SiNx cover layers.

  4. The Fluence and Distance Distributions of Fast Radio Bursts

    Vedantham, H K; Hallinan, G; Shannon, R

    2016-01-01

    Fast radio bursts (FRB) are millisecond-duration radio pulses with apparent extragalactic origins. All but two of the FRBs have been discovered using the Parkes dish which employs multiple beams formed by an array of feed horns on its focal plane. In this paper, we show that (i) the preponderance of multiple-beam detections, and (ii) the detection rates for varying dish diameters, can be used to infer the index $\\alpha$ of the cumulative fluence distribution function (the log$N$-log$F$ function: $\\alpha=1.5$ for a non-evolving population in a Euclidean universe). If all detected FRBs arise from a single progenitor population, multiple-beam FRB detection rates from the Parkes telescope yield the constraint $0.52<\\alpha<1.0$ with $90$% confidence. Searches at other facilities with different dish sizes refine the constraint to $0.66<\\alpha<0.96$. Our results favor FRB searches with smaller dishes, because for $\\alpha<1$, the gain in field-of-view for a smaller dish is more important than the reduc...

  5. Fluence thresholds for grazing incidence hard x-ray mirrors

    Aquila, A.; Ozkan, C.; Sinn, H.; Tschentscher, T.; Mancuso, A. P.; Gaudin, J. [European XFEL GmbH, Albert-Einstein-Ring 19, Hamburg D-22671 (Germany); Sobierajski, R.; Klepka, M. T.; Dłużewski, P.; Morawiec, K. [Institute of Physics, PAS Al. Lotnikw 32/46, Warsaw PL-02-668 (Poland); Hájková, V.; Burian, T.; Chalupský, J.; Juha, L. [Institute of Physics, ASCR, Na Slovance 2, CZ 182 21 Prague 8 (Czech Republic); Störmer, M. [Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, Geesthacht D-21502 (Germany); Bajt, S. [Deutsches Elektronen-Synchrotron, Notkestraße 85, Hamburg D-22607 (Germany); Ohashi, H.; Koyama, T.; Tono, K. [RIKEN/SPring-8 Kouto 1-1-1, Sayo, Hyogo 679-5148 (Japan); Japan Synchrotron Radiation Research Institute (JASRI), Kouto 1-1-1, Sayo, Hyogo 679-5198 (Japan); Inubushi, Y. [RIKEN/SPring-8 Kouto 1-1-1, Sayo, Hyogo 679-5148 (Japan); and others

    2015-06-15

    X-ray Free Electron Lasers (XFELs) have the potential to contribute to many fields of science and to enable many new avenues of research, in large part due to their orders of magnitude higher peak brilliance than existing and future synchrotrons. To best exploit this peak brilliance, these XFEL beams need to be focused to appropriate spot sizes. However, the survivability of X-ray optical components in these intense, femtosecond radiation conditions is not guaranteed. As mirror optics are routinely used at XFEL facilities, a physical understanding of the interaction between intense X-ray pulses and grazing incidence X-ray optics is desirable. We conducted single shot damage threshold fluence measurements on grazing incidence X-ray optics, with coatings of ruthenium and boron carbide, at the SPring-8 Angstrom compact free electron laser facility using 7 and 12 keV photon energies. The damage threshold dose limits were found to be orders of magnitude higher than would naively be expected. The incorporation of energy transport and dissipation via keV level energetic photoelectrons accounts for the observed damage threshold.

  6. Solid phase epitaxy of amorphous silicon carbide: Ion fluence dependence

    We have investigated the effect of radiation damage and impurity concentration on solid phase epitaxial growth of amorphous silicon carbide (SiC) as well as microstructures of recrystallized layer using transmission electron microscopy. Single crystals of 6H-SiC with (0001) orientation were irradiated with 150 keV Xe ions to fluences of 1015 and 1016/cm2, followed by annealing at 890 deg. C. Full epitaxial recrystallization took place in a specimen implanted with 1015 Xe ions, while retardation of recrystallization was observed in a specimen implanted with 1016/cm2 Xe ions. Atomic pair-distribution function analyses and energy dispersive x-ray spectroscopy results suggested that the retardation of recrystallization of the 1016 Xe/cm2 implanted sample is attributed to the difference in amorphous structures between the 1015 and 1016 Xe/cm2 implanted samples, i.e., more chemically disordered atomistic structure and higher Xe impurity concentration in the 1016 Xe/cm2 implanted sample

  7. Effect of fluence on carbon nanostructures produced by laser ablation in liquid nitrogen

    Tabatabaie, Nushin; Dorranian, Davoud

    2016-05-01

    Effects of laser fluence on the properties of carbon nanostructures produced by laser ablation method in liquid nitrogen have been studied experimentally. The beam of a Q-switched Nd:YAG laser of 1064-nm wavelength at 7 ns pulse width and different fluences is employed to irradiate the graphite target in liquid nitrogen. Properties of carbon nanostructures were studied using their UV-Vis-NIR spectrum, TEM images, and Raman scattering spectrum. Two categories of graphene nanosheets and carbon nanoparticles were observed due to variation of laser fluence. Results show that in our experimental condition there is a threshold fluence for producing carbon nanoparticles. With increasing the laser fluence from the threshold, the amount of carbon nanoparticles in suspensions was increased, while the amount of graphene nanosheets was decreased.

  8. Effect of Pulse Width and Fluence of Femtosecond Laser on Electron-Phonon Relaxation Time

    FANG Ran-Ran; ZHANG Duan-Ming; WEI Hua; LI Zhi-Hua; YANG Feng-Xia; TAN Xin-Yu

    2008-01-01

    The electron-phonon relaxation time as functions of pulse width and fluence of femtosecond laser is studied based on the two-temperature model. The two-temperature model is solved using a finite difference method for copper target. The temperature distribution of the electron and the lattice along with space and time for a certain laser fluence is presented. The time-dependence of lattice and electron temperature of the surface for different pulse width and different laser fluence are also performed, respectively. Moreover, the variation of heat-affected zone per pulse with laser fluence is obtained. The satisfactory agreement between our numerical results and experimental data indicates that the electron-phonon relaxation time is reasonably accurate with the influences of pulse width and fluence of femtosecond laser.

  9. Measured Thermal and Fast Neutron Fluence Rates for ATF-1 Holders During ATR Cycle 157D

    Smith, Larry Don [Idaho National Lab. (INL), Idaho Falls, ID (United States); Miller, David Torbet [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-03-01

    This report contains the thermal (2200 m/s) and fast (E>1MeV) neutron fluence rate data for the ATF-1 holders located in core for ATR Cycle 157D which were measured by the Radiation Measurements Laboratory (RML) as requested by the Power Reactor Programs (ATR Experiments) Radiation Measurements Work Order. This report contains measurements of the fluence rates corresponding to the particular elevations relative to the 80-ft. core elevation. The data in this report consist of (1) a table of the ATR power history and distribution, (2) a hard copy listing of all thermal and fast neutron fluence rates, and (3) plots of both the thermal and fast neutron fluence rates. The fluence rates reported are for the average power levels given in the table of power history and distribution.

  10. Tissue-specific accumulation and lactational transfer of polychlorinated biphenyls, chlorinated pesticides, and brominated flame retardants in hooded seals (Cistophora cristata) from the Gulf of St. Lawrence: Applications for monitoring

    Accumulation and mother-pup transfer of halogenated organic contaminants was studied in hooded seal tissues from eastern Canada. Blubber polychlorinated biphenyl (PCB) and total pesticide concentrations were relatively high, possibly due to their high trophic level and demersal feeding habits. Blood plasma showed the lowest contaminant concentrations compared to blubber and liver, possibly due to a lower affinity of these compounds to lipoproteins in blood plasma. Total contaminant body burden correlated well with blubber, liver, and milk contaminants, but not with blood plasma contaminants, indicating that blood plasma might be less suitable to monitor contaminants in hooded seals. Lactational transfer favored less lipophilic contaminants and was associated with relatively high blood plasma PCB and polybrominated diphenyl ether concentrations in females. Despite lactational transfer, females did not show significantly lower blubber contaminant concentrations or burdens than males. This might be caused by their low blubber, and thus contaminant, loss during lactation compared to other species. - Blood plasma contaminant concentrations differ from those in other tissues and might therefore be unsuitable for contaminant monitoring in hooded seals

  11. Ion implantation induced by Cu ablation at high laser fluence

    High energy laser plasma-produced Cu ions have been implanted in silicon substrates placed at different distances and angles with respect to the normal to the surface of the ablated target. The implanted samples have been produced using the iodine high power Prague Asterix Laser System (PALS) using 438 nm wavelength irradiating in vacuum a Cu target. The high laser pulse energy (up to 230 J) and the short pulse duration (400 ps) produced a non-equilibrium plasma expanding mainly along the normal to the Cu target surface. Time-of-flight (TOF) technique was employed, through an electrostatic ion energy analyzer (IEA) placed along the target normal, in order to measure the ion energy, the ion charge state, the energy distribution and the charge state distribution. Ions had a Boltzmann energy distributions with an energy increasing with the charge state. At a laser fluence of the order of 6 x 106 J/cm2, the maximum ion energy was about 600 keV and the maximum charge state was about 27+. In order to investigate the implantation processes, Cu depth profiles have been performed with Rutherford backscattering spectrometry (RBS) of 1.5 MeV helium ions, Auger electron spectroscopy (AES) with 3 keV electron beam and 1 keV Ar sputtering ions in combination with scanning electron microscopy (SEM). Surface analysis results indicate that Cu ions are implanted within the first surface layers and that the ion penetration ranges are in agreement with the ion energy measured with IEA analysis

  12. Ultra-fast fluence optimization for beam angle selection algorithms

    Bangert, M.; Ziegenhein, P.; Oelfke, U.

    2014-03-01

    Beam angle selection (BAS) including fluence optimization (FO) is among the most extensive computational tasks in radiotherapy. Precomputed dose influence data (DID) of all considered beam orientations (up to 100 GB for complex cases) has to be handled in the main memory and repeated FOs are required for different beam ensembles. In this paper, the authors describe concepts accelerating FO for BAS algorithms using off-the-shelf multiprocessor workstations. The FO runtime is not dominated by the arithmetic load of the CPUs but by the transportation of DID from the RAM to the CPUs. On multiprocessor workstations, however, the speed of data transportation from the main memory to the CPUs is non-uniform across the RAM; every CPU has a dedicated memory location (node) with minimum access time. We apply a thread node binding strategy to ensure that CPUs only access DID from their preferred node. Ideal load balancing for arbitrary beam ensembles is guaranteed by distributing the DID of every candidate beam equally to all nodes. Furthermore we use a custom sorting scheme of the DID to minimize the overall data transportation. The framework is implemented on an AMD Opteron workstation. One FO iteration comprising dose, objective function, and gradient calculation takes between 0.010 s (9 beams, skull, 0.23 GB DID) and 0.070 s (9 beams, abdomen, 1.50 GB DID). Our overall FO time is < 1 s for small cases, larger cases take ~ 4 s. BAS runs including FOs for 1000 different beam ensembles take ~ 15-70 min, depending on the treatment site. This enables an efficient clinical evaluation of different BAS algorithms.

  13. Development of highly efficient proton recoil counter telescope for absolute measurement of neutron fluences in quasi-monoenergetic neutron calibration fields of high energy

    Precise calibration of monitors and dosimeters for use with high energy neutrons necessitates reliable and accurate neutron fluences being evaluated with use of a reference point. A highly efficient Proton Recoil counter Telescope (PRT) to make absolute measurements with use of a reference point was developed to evaluate neutron fluences in quasi-monoenergetic neutron fields. The relatively large design of the PRT componentry and relatively thick, approximately 2 mm, polyethylene converter contributed to high detection efficiency at the reference point over a large irradiation area at a long distance from the target. The polyethylene converter thickness was adjusted to maintain the same carbon density per unit area as the graphite converter for easy background subtraction. The high detection efficiency and thickness adjustment resulted in efficient absolute measurements being made of the neutron fluences of sufficient statistical precision over a short period of time. The neutron detection efficiencies of the PRT were evaluated using MCNPX code at 2.61x10-6, 2.16x10-6 and 1.14x10-6 for the respective neutron peak energies of 45, 60 and 75 MeV. The neutron fluences were determined to have been evaluated at an uncertainty of within 6.5% using analysis of measured data and the detection efficiencies. The PRT was also designed so as to be capable of simultaneously obtaining TOF data. The TOF data also increased the reliability of neutron fluence measurements and provided useful information for use in interpreting the source of proton events.

  14. Effect of UVA Fluence Rate on Indicators of Oxidative Stress in Human Dermal Fibroblasts

    James D. Hoerter, Christopher S. Ward, Kyle D. Bale, Admasu N. Gizachew, Rachelle Graham, Jaclyn Reynolds, Melanie E. Ward, Chesca Choi, Jean-Leonard Kagabo, Michael Sauer, Tara Kuipers, Timothy Hotchkiss, Nate Banner, Renee A. Chellson, Theresa Ohaeri, L

    2008-01-01

    Full Text Available During the course of a day human skin is exposed to solar UV radiation that fluctuates in fluence rate within the UVA (290-315 nm and UVB (315-400 nm spectrum. Variables affecting the fluence rate reaching skin cells include differences in UVA and UVB penetrating ability, presence or absence of sunscreens, atmospheric conditions, and season and geographical location where the exposure occurs. Our study determined the effect of UVA fluence rate in solar-simulated (SSR and tanning-bed radiation (TBR on four indicators of oxidative stress---protein oxidation, glutathione, heme oxygenase-1, and reactive oxygen species--in human dermal fibroblasts after receiving equivalent UVA and UVB doses. Our results show that the higher UVA fluence rate in TBR increases the level of all four indicators of oxidative stress. In sequential exposures when cells are exposed first to SSR, the lower UVA fluence rate in SSR induces a protective response that protects against oxidative stress following a second exposure to a higher UVA fluence rate. Our studies underscore the important role of UVA fluence rate in determining how human skin cells respond to a given dose of radiation containing both UVA and UVB radiation.

  15. Photoluminescence and reflectivity of polymethylmethacrylate implanted by low-energy carbon ions at high fluences

    Highlights: ► Photoluminescence was studied in carbon implanted polymethylmethacrylate (PMMA). ► A significant photoluminescence enhancement occurred at ion fluence of 5 × 1016 cm−2. ► Photoluminescence and Raman responses revealed carbon nanoclustered structures. ► Reflectivity of carbon implanted PMMA depended on both ion fluence and wavelength. ► A noticeable reflectivity modification appeared at ion fluence of 1 × 1016 cm−2. - Abstract: Polymethylmethacrylate (PMMA) specimens were implanted with 30 keV carbon ions in a fluence range of 1 × 1016 to 2 × 1017 cm−2, and photoluminescence (PL) and reflectivity of the implanted samples were examined. A luminescent band with one peak was found in PL spectra excited by 480 nm line, but its intensity did not vary in parallel with ion fluence. The strongest PL occurred at the fluence of 5 × 1016 cm−2. Results from visible-light-excited micro-Raman spectra indicated that the formation of hydrogenated amorphous carbon structures in subsurface layer and their evolutions with ion fluence could be responsible for the observed PL responses. Measurements of the small-angle reflectance spectra from both the implanted and rear surfaces of samples in the ultraviolet–visible (UV–vis) range demonstrated a kind of both fluence-dependent and wavelength-related reflectivity variations, which were attributed to the structural changes induced by ion implantation. A noticeable reflectivity modification, which may be practically used, could be found at the fluence of 1 × 1016 cm−2.

  16. Photoluminescence and reflectivity of polymethylmethacrylate implanted by low-energy carbon ions at high fluences

    Wang Jun; Zhu Fei; Zhang Bei; Liu Huixian; Jia Guangyi [School of Science, Tianjin University, Tianjin 300072 (China); Liu Changlong, E-mail: liuchanglong@tju.edu.cn [School of Science, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Institute of Advanced Materials Physics Faculty of Science, Tianjin 300072 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Photoluminescence was studied in carbon implanted polymethylmethacrylate (PMMA). Black-Right-Pointing-Pointer A significant photoluminescence enhancement occurred at ion fluence of 5 Multiplication-Sign 10{sup 16} cm{sup -2}. Black-Right-Pointing-Pointer Photoluminescence and Raman responses revealed carbon nanoclustered structures. Black-Right-Pointing-Pointer Reflectivity of carbon implanted PMMA depended on both ion fluence and wavelength. Black-Right-Pointing-Pointer A noticeable reflectivity modification appeared at ion fluence of 1 Multiplication-Sign 10{sup 16} cm{sup -2}. - Abstract: Polymethylmethacrylate (PMMA) specimens were implanted with 30 keV carbon ions in a fluence range of 1 Multiplication-Sign 10{sup 16} to 2 Multiplication-Sign 10{sup 17} cm{sup -2}, and photoluminescence (PL) and reflectivity of the implanted samples were examined. A luminescent band with one peak was found in PL spectra excited by 480 nm line, but its intensity did not vary in parallel with ion fluence. The strongest PL occurred at the fluence of 5 Multiplication-Sign 10{sup 16} cm{sup -2}. Results from visible-light-excited micro-Raman spectra indicated that the formation of hydrogenated amorphous carbon structures in subsurface layer and their evolutions with ion fluence could be responsible for the observed PL responses. Measurements of the small-angle reflectance spectra from both the implanted and rear surfaces of samples in the ultraviolet-visible (UV-vis) range demonstrated a kind of both fluence-dependent and wavelength-related reflectivity variations, which were attributed to the structural changes induced by ion implantation. A noticeable reflectivity modification, which may be practically used, could be found at the fluence of 1 Multiplication-Sign 10{sup 16} cm{sup -2}.

  17. MACK, Fluence to Kerma Generator from ENDF/B

    1 - Nature of physical problem solved: The principal purpose of the program is in calculating pointwise neutron energy release parameters (fluence-to-kerma factors) at an arbitrary energy mesh from nuclear data in ENDF/B format (2). The kerma factors are of prime importance for calculating heating and dose rates in any nuclear system. The program processes all reactions significant to energy deposition. In addition, the program calculates energy group kerma factors and group cross sections by reactions (group constants not transfer matrices) averaged over an arbitrary input weighting function or any of the 'built-in' functions. When resonance data is available, the code calculates the contribution from the resolved and unresolved resonance parameters. The pointwise cross sections, pointwise kerma factors, energy group cross sections and energy group kerma factors can be printed, punched, and/or saved on tape for all reactions and the sum as selected by input. The pointwise kerma factors can be saved for later use (3) to generate group kerma factors for a different energy group structure or possibly for inclusion in the ENDF/B evaluation for the nuclide with the appropriate MT numbers in the 300's series (2). 2 - Method of solution: The expressions for the energy release per reaction are obtained from a solution of the kinematics of nuclear reactions. The anisotropy of elastic and inelastic scattering is considered. The contribution to energy deposition from radioactive decay of the residual nucleus can be added by reaction and is calculated using Fermi theory in the case of beta decay. In the resolved resonance region, MACK accepts either single or multi level Breit-Wigner parameters. Doppler broadening is performed at an arbitrary input temperature. The unresolved resonance treatment includes some shielding effects through a 1/sigma t weighting. The energy group kerma factors and cross sections are calculated by averaging the pointwise data over either a user

  18. Fluence correction factors for graphite calorimetry in a low-energy clinical proton beam: I. Analytical and Monte Carlo simulations

    Palmans, Hugo; Al-Sulaiti, L; Andreo, P;

    2013-01-01

    charged particles is considered, the fluence correction factor is about 0.5% lower than unity at shallow depths predominantly due to the contributions from alpha particles and increases to values above unity near the Bragg peak. Fluence correction factors directly derived from the fluence distributions...

  19. Flux and fluence dependence of implantation disorder in GaAs substrates

    A previously presented technique of measuring radiation damage using electroreflectance (ER) measurement is used to detect disorder dependencies for light and heavy ions as a function of flux and fluence. Lighter-mass ions (Ne, N, and O) cause increasing damage with increasing flux for fluences less than 5 x 1013 cm-2 because of the decrease in radiation-enhanced annealing. At higher fluences, the damage decreases with increasing flux probably because of thermal annealing. Heavy ions (Cd, Te, and Xe) exhibit the same type of behavior but at lower fluences because of the smaller penetration depths. The ER measurements of damage in ion-implanted GaAs show clearly that the radiation-enhanced and thermal-annealing processes depend upon the energy density and damage concentration in the crystal

  20. Ultra-short pulsed laser ablation of silicon nitride layers: Investigation near threshold fluence

    Heinrich, Gerrit, E-mail: gheinrich@cismst.de [CIS Forschungsinstititut für Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Straße 14, Erfurt 99099 (Germany); Technische Universität Ilmenau, Institut für Physik, Weimarer Str. 32, Ilmenau 98693 (Germany); Wollgarten, Markus [Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Bereich Solarenergieforschung, Institut für Technologie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Bähr, Mario; Lawerenz, Alexander [CIS Forschungsinstititut für Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Straße 14, Erfurt 99099 (Germany)

    2013-08-01

    In this work, silicon nitride (SiN{sub x}) layers, deposited on a planar silicon wafer are locally irradiated by ultra short laser pulses with fluences near the threshold fluence. The irradiated areas are investigated by SEM and TEM in order to analyze the laser influence to silicon and to the SiN{sub x} layer. Thereby, a lift-off process is observed for this SiN{sub x} layer. The silicon absorbs the laser pulse energy. For low fluences, crystalline silicon is disordered below the SiN{sub x} layer. For high fluences, silicon evaporates below the SiN{sub x} layer and bulge the SiN{sub x} layer. If the pressure within the bulge is high enough, the SiN{sub x} layer will break down due to high mechanical stress.

  1. Curved gratings as an integrated photon fluence monitor in x-ray transmission scattering experiments.

    Schneider, Michael; Günther, Christian Michael; von Korff Schmising, Clemens; Pfau, Bastian; Eisebitt, Stefan

    2016-06-13

    A concept to obtain a measure of the photon flux accepted by a solid sample in single-shot transmission experiments with extreme ultraviolet (XUV) or soft x-ray radiation is demonstrated. Shallow, continuously distorted gratings are used to diffract a constant fraction of the incident photons onto an extended area of a CCD detector. The signal can be tailored to fit the dynamic range of the detector, i.e. matching the scattered intensity of the studied structure of interest. Furthermore, composite grating designs that also allow for the measurement of the spatial photon distribution on the sample are demonstrated. The gratings are directly fabricated by focused ion-beam (FIB) lithography into a Si3N4 membrane that supports the actual sample layer. This allows for rapid fabrication of hundreds of samples, making the concept suitable for systematic studies in destructive single-shot measurements at free-electron laser (FEL) sources. We demonstrate relative photon flux measurements in magnetic scattering experiments with synchrotron and FEL radiation at 59.6 eV photon energy. PMID:27410328

  2. Determination of gamma dose and neutron fluence during start-up of the Greifswald-1 reactor

    During start-up of the Greifswald-1 reactor gamma and neutron radiation was measured using activation probes and thermoluminescent detectors which provided more accurate results than colorimetric dosemeters and solid state track detectors. A correlation was found between the n,γ field intensity and reactor power. The spatial distribution of the gamma dose and neutron fluence resulted in corresponding values. The spectral fluence distribution confirmed the existence of a soft neutron spectrum

  3. Verification of the algorithm of sum of fluences for quality control in IMRT

    In prior to each IMRT treatment quality control measures face are made to verify the match between the Royal treatment and details of the Planner. verified values of absolute dose at different points of a mannequin, the distribution of doses of all the fields (individual fluences), and the distribution of dose in the treatment full (global creep). This paper compares the distribution of doses for the full treatment measurement with that obtained by combining data from the fluences of the individual fields. (Author)

  4. A fast heterogeneous algorithm for light fluence rate for prostate photodynamic therapy

    Chang, Chang; Wang, Ken K.-H; Zhu, Timothy C.

    2010-01-01

    To accurately calculate light fluence rate distribution in prostate photodynamic therapy (PDT), optical heterogeneity has to be taken into account. Previous study has shown that a kernel based on analytic solution of the diffusion equation can perform the calculation with accuracy comparable to Finite-element method. An assumption is made that light fluence rate detected at a point in the medium is affected primarily by the optical properties of points (or elements) on the line between the so...

  5. Ablation mechanism study on metallic materials with a 10 ps laser under high fluence

    Single shot ablation of metallic materials of aluminium, titanium alloy (Ti6Al4V) and gold has been studied with 10 picoseconds (ps) laser pulses experimentally and theoretically. The ablation rate variation at high fluence was explained by a simplified predictive model based on critical-point phase separation (CPPS) theory. A comparison between experimental and numerical results inferred that CPPS may well be the dominant ablation mechanism for high fluence laser ablation at 10 ps laser duration.

  6. Lifetime Neutron Fluence Analysis of the Ringhals Unit 1 Boiling Water Reactor

    Kulesza Joel A.; Roudén Jenny; Green Eva-Lena

    2016-01-01

    This paper describes a neutron fluence assessment considering the entire commercial operating history (35 cycles or ∼ 25 effective full power years) of the Ringhals Unit 1 reactor pressure vessel beltline region. In this assessment, neutron (E >1.0 MeV) fluence and iron atom displacement distributions were calculated on the moderator tank and reactor pressure vessel structures. To validate those calculations, five in-vessel surveillance chain dosimetry sets were evaluated as well as material ...

  7. Influence of hydrogen fluence on surface blistering of H and He co-implanted Ge

    Dai, Jiayun; Xue, Zhongying; Zhang, Miao; Wei, Xing; Wang, Gang; Di, Zengfeng

    2016-02-01

    The effect of hydrogen fluence on surface blistering of H and He co-implanted Ge is investigated using atom force microscope, X-ray diffraction and transmission electron microscopy. With a fixed He, we find that for 1 × 1016 cm-2 H implantation fluence, only a few small dome-shaped blisters appear, for 3 × 1016 cm-2 H implantation fluence, large blisters as well as craters are formed, while for 5 × 1016 cm-2 H implantation fluence, no blisters can be observed. The strain evolution and platelet forming tendency are found to be relevant for the different blistering phenomenon. The weak blistering phenomenon for 1 × 1016 cm-2 H implantation fluence may be attributed to less "free" H for the building up of internal pressure of platelets and the sustained growth of platelets. While the absence of blistering phenomenon for 5 × 1016 cm-2 H implantation fluence is likely due to the retarded relief of the decreased uniform compressive stress throughout the damage region.

  8. Influence of fluence rate on radiation-induced mechanical property changes in reactor pressure vessel steels

    Hawthorne, J.R.; Hiser, A.L. (Materials Engineering Associates, Inc., Lanham, MD (USA))

    1990-03-01

    This report describes a set of experiments undertaken using a 2 MW test reactor, the UBR, to qualify the significance of fluence rate to the extent of embrittlement produced in reactor pressure vessel steels at their service temperature. The test materials included two reference plates (A 302-B, A 533-B steel) and two submerged arc weld deposits (Linde 80, Linde 0091 welding fluxes). Charpy-V (C{sub v}), tension and 0.5T-CT compact specimens were employed for notch ductility, strength and fracture toughness (J-R curve) determinations, respectively. Target fluence rates were 8 {times} 10{sup 10}, 6 {times} 10{sup 11} and 9 {times} 10{sup 12} n/cm{sup 2} {minus}s{sup {minus}1}. Specimen fluences ranged from 0.5 to 3.8 {times} 10{sup 19} n/cm{sup 2}, E > 1 MeV. The data describe a fluence-rate effect which may extend to power reactor surveillance as well as test reactor facilities now in use. The dependence of embrittlement sensitivity on fluence rate appears to differ for plate and weld deposit materials. Relatively good agreement in fluence-rate effects definition was observed among the three test methods. 52 figs., 4 tabs.

  9. Empirical assessment of the detection efficiency of CR-39 at high proton fluence and a compact, proton detector for high-fluence applications

    Rosenberg, M. J., E-mail: mrosenbe@mit.edu; Séguin, F. H.; Waugh, C. J.; Rinderknecht, H. G.; Orozco, D.; Frenje, J. A.; Johnson, M. Gatu; Sio, H.; Zylstra, A. B.; Sinenian, N.; Li, C. K.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Glebov, V. Yu.; Stoeckl, C.; Hohenberger, M.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); LePape, S.; Mackinnon, A. J.; Bionta, R. M.; Landen, O. L. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2014-04-15

    CR-39 solid-state nuclear track detectors are widely used in physics and in many inertial confinement fusion (ICF) experiments, and under ideal conditions these detectors have 100% detection efficiency for ∼0.5–8 MeV protons. When the fluence of incident particles becomes too high, overlap of particle tracks leads to under-counting at typical processing conditions (5 h etch in 6N NaOH at 80 °C). Short etch times required to avoid overlap can cause under-counting as well, as tracks are not fully developed. Experiments have determined the minimum etch times for 100% detection of 1.7–4.3-MeV protons and established that for 2.4-MeV protons, relevant for detection of DD protons, the maximum fluence that can be detected using normal processing techniques is ≲3 × 10{sup 6} cm{sup −2}. A CR-39-based proton detector has been developed to mitigate issues related to high particle fluences on ICF facilities. Using a pinhole and scattering foil several mm in front of the CR-39, proton fluences at the CR-39 are reduced by more than a factor of ∼50, increasing the operating yield upper limit by a comparable amount.

  10. Empirical assessment of the detection efficiency of CR-39 at high proton fluence and a compact, proton detector for high-fluence applications

    CR-39 solid-state nuclear track detectors are widely used in physics and in many inertial confinement fusion (ICF) experiments, and under ideal conditions these detectors have 100% detection efficiency for ∼0.5–8 MeV protons. When the fluence of incident particles becomes too high, overlap of particle tracks leads to under-counting at typical processing conditions (5 h etch in 6N NaOH at 80 °C). Short etch times required to avoid overlap can cause under-counting as well, as tracks are not fully developed. Experiments have determined the minimum etch times for 100% detection of 1.7–4.3-MeV protons and established that for 2.4-MeV protons, relevant for detection of DD protons, the maximum fluence that can be detected using normal processing techniques is ≲3 × 106 cm−2. A CR-39-based proton detector has been developed to mitigate issues related to high particle fluences on ICF facilities. Using a pinhole and scattering foil several mm in front of the CR-39, proton fluences at the CR-39 are reduced by more than a factor of ∼50, increasing the operating yield upper limit by a comparable amount

  11. Determination of the Neutron Fluence, the Beam Characteristics and the Backgrounds at the CERN-PS TOF Facility

    Leal, L C; Kitis, G; Guber, K H; Quaranta, A; Koehler, P E

    2002-01-01

    In the scope of our programme we propose to start in July 2000 with measurements on elements of well known cross sections, in order to check the reliability of the whole experimental installation at the CERN-TOF facility. These initial exploratory measurements will provide the key-parameters required for the further experimentation at the CERN-TOF neutron beam. The neutron fluence and energy resolution will be determined as a function of the neutron kinetic energy by reproducing standard capture and fission cross sections. The measurements of capture cross sections on elements with specific cross section features will allow to us to disentangle the different components of backgrounds and estimate their level in the experimental area. The time-energy calibration will be determined and monitored with a set of monoenergetic filters as well as by the measurements of elements with resonance-dominated cross sections. Finally, in this initial phase the behaviour of several detectors scheduled in successive measureme...

  12. Calculation of neutron fluence to dose equivalent conversion coefficients using GEANT4; Calculo de coeficientes de fluencia de neutrons para equivalente de dose individual utilizando o GEANT4

    Ribeiro, Rosane M.; Santos, Denison de S.; Queiroz Filho, Pedro P. de; Mauricio, CLaudia L.P.; Silva, Livia K. da; Pessanha, Paula R., E-mail: rosanemribeiro@oi.com.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2014-07-01

    Fluence to dose equivalent conversion coefficients provide the basis for the calculation of area and personal monitors. Recently, the ICRP has started a revision of these coefficients, including new Monte Carlo codes for benchmarking. So far, little information is available about neutron transport below 10 MeV in tissue-equivalent (TE) material performed with Monte Carlo GEANT4 code. The objective of this work is to calculate neutron fluence to personal dose equivalent conversion coefficients, H{sub p} (10)/Φ, with GEANT4 code. The incidence of monoenergetic neutrons was simulated as an expanded and aligned field, with energies ranging between thermal neutrons to 10 MeV on the ICRU slab of dimension 30 x 30 x 15 cm{sup 3}, composed of 76.2% of oxygen, 10.1% of hydrogen, 11.1% of carbon and 2.6% of nitrogen. For all incident energy, a cylindrical sensitive volume is placed at a depth of 10 mm, in the largest surface of the slab (30 x 30 cm{sup 2}). Physic process are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles which reach the sensitive volume. Results obtained are thus compared with values published in ICRP 74. Neutron fluence in the sensitive volume was calculated for benchmarking. The Monte Carlo GEANT4 code was found to be appropriate to calculate neutron doses at energies below 10 MeV correctly. (author)

  13. Equivalent electron fluence for solar proton damage in GaAs shallow junction cells

    Wilson, J. W.; Stock, L. V.

    The short-circuit current reduction in GaAs shallow junction heteroface solar cells was calculated according to a simplified solar cell damage model in which the nonuniformity of the damage as a function of penetration depth is treated explicitly. Although the equivalent electron fluence was not uniquely defined for low-energy monoenergetic proton exposure, an equivalent electron fluence is found for proton spectra characteristic of the space environment. The equivalent electron fluence ratio was calculated for a typical large solar flare event for which the proton spectrum is PHI(sub p)(E) = A/E(p/sq. cm) where E is in MeV. The equivalent fluence ratio is a function of the cover glass shield thickness or the corresponding cutoff energy E(sub c). In terms of the cutoff energy, the equivalent 1 MeV electron fluence ratio is r(sub p)(E sub c) = 10(9)/E(sub c)(1.8) where E(sub c) is in units of KeV.

  14. Femtosecond laser ablation of dentin and enamel: relationship between laser fluence and ablation efficiency

    Chen, Hu; Liu, Jing; Li, Hong; Ge, Wenqi; Sun, Yuchun; Wang, Yong; Lü, Peijun

    2015-02-01

    The objective was to study the relationship between laser fluence and ablation efficiency of a femtosecond laser with a Gaussian-shaped pulse used to ablate dentin and enamel for prosthodontic tooth preparation. A diode-pumped thin-disk femtosecond laser with wavelength of 1025 nm and pulse width of 400 fs was used for the ablation of dentin and enamel. The laser spot was guided in a line on the dentin and enamel surfaces to form a groove-shaped ablation zone under a series of laser pulse energies. The width and volume of the ablated line were measured under a three-dimensional confocal microscope to calculate the ablation efficiency. Ablation efficiency for dentin reached a maximum value of 0.020 mm3/J when the laser fluence was set at 6.51 J/cm2. For enamel, the maximum ablation efficiency was 0.009 mm3/J at a fluence of 7.59 J/cm2. Ablation efficiency of the femtosecond laser on dentin and enamel is closely related to the laser fluence and may reach a maximum when the laser fluence is set to an appropriate value.

  15. Recrystallization behavior of high-fluence N+-implanted GaAs studied by Raman spectroscopy

    Raman spectroscopy was used to study the evolution of host lattice recrystallization in high-fluence N+-implanted GaAs. A high-fluence of N+ ions (>1015 cm-2) was introduced into semi-insulating GaAs by the combinatorial implantation method. Subsequent thermal annealing at 800 deg. C was carried out to re-grow the implantation-induced amorphous layers. The dependence of Raman parameters on N contents was systematically observed for each recrystallized cell. The volume of the newly formed crystallites with original orientation decreases with increasing fluences, whereas that of crystallites of other orientations increases after high-fluence implantation and annealing. The correlation length L, representing the size of crystalline regions with preserved translational symmetry, was determined by fitting the LO phonon signal with spatial correlation model. For 1016 cm-2 implantation, the recrystallized layer consists of nano-meter-sized crystallites (∼30 nm). The dimension of the recrystallized crystallites decreases with increasing N+ fluences, in good agreement with the model

  16. Coupling of Monte Carlo adjoint leakages with three-dimensional discrete ordinates forward fluences

    A computer code, DRC3, has been developed for coupling Monte Carlo adjoint leakages with three-dimensional discrete ordinates forward fluences in order to solve a special category of geometrically-complex deep penetration shielding problems. The code extends the capabilities of earlier methods that coupled Monte Carlo adjoint leakages with two-dimensional discrete ordinates forward fluences. The problems involve the calculation of fluences and responses in a perturbation to an otherwise simple two- or three-dimensional radiation field. In general, the perturbation complicates the geometry such that it cannot be modeled exactly using any of the discrete ordinates geometry options and thus a direct discrete ordinates solution is not possible. Also, the calculation of radiation transport from the source to the perturbation involves deep penetration. One approach to solving such problems is to perform the calculations in three steps: (1) a forward discrete ordinates calculation, (2) a localized adjoint Monte Carlo calculation, and (3) a coupling of forward fluences from the first calculation with adjoint leakages from the second calculation to obtain the response of interest (fluence, dose, etc.). A description of this approach is presented along with results from test problems used to verify the method. The test problems that were selected could also be solved directly by the discrete ordinates method. The good agreement between the DRC3 results and the direct-solution results verify the correctness of DRC3

  17. Coupling of Monte Carlo adjoint leakages with three-dimensional discrete ordinates forward fluences

    Slater, C.O.; Lillie, R.A.; Johnson, J.O.; Simpson, D.B.

    1998-04-01

    A computer code, DRC3, has been developed for coupling Monte Carlo adjoint leakages with three-dimensional discrete ordinates forward fluences in order to solve a special category of geometrically-complex deep penetration shielding problems. The code extends the capabilities of earlier methods that coupled Monte Carlo adjoint leakages with two-dimensional discrete ordinates forward fluences. The problems involve the calculation of fluences and responses in a perturbation to an otherwise simple two- or three-dimensional radiation field. In general, the perturbation complicates the geometry such that it cannot be modeled exactly using any of the discrete ordinates geometry options and thus a direct discrete ordinates solution is not possible. Also, the calculation of radiation transport from the source to the perturbation involves deep penetration. One approach to solving such problems is to perform the calculations in three steps: (1) a forward discrete ordinates calculation, (2) a localized adjoint Monte Carlo calculation, and (3) a coupling of forward fluences from the first calculation with adjoint leakages from the second calculation to obtain the response of interest (fluence, dose, etc.). A description of this approach is presented along with results from test problems used to verify the method. The test problems that were selected could also be solved directly by the discrete ordinates method. The good agreement between the DRC3 results and the direct-solution results verify the correctness of DRC3.

  18. Burnup influence on the VVER-1000 reactor vessel neutron fluence evaluation

    The neutron fluence of the vessels of the reactors is determined regularly accordingly the RPV Surveillance Program of the Kozloduy NPP Unit 5 and 6 in order to assess the state of the metal vessel and their radiation damaging. The calculations are carried out by the method of discrete ordinates used in the TORT program for operated reactor cycles. An average reactor spectrum corresponding to fresh U-235 fuel is used as an input neutron source. The impact of the burn up of the fuel on the neutron fluence of VVER-1000 reactor vessel is evaluated. The calculations of isotopic concentrations of U-235 and Pu-239 corresponding to 4 years burn up were performed by the module SAS2H of the code system SCALE 4.4. Since fresh fuel or 4 years burn up fuel assembly are placed in periphery of reactor core the contribution of Pu-239 of first year burn up and of 4 years burn up is taken in consideration. Calculations of neutron fluence were performed with neutron spectrum for fresh fuel, for 1 year and for 4 years burn up fuel. Correction factors for neutron fluence at the inner surface of the reactor vessel, in 1/4 depth of the vessel and in the air behind the vessel were obtained. The correction coefficient could be used when the neutron fluence is assessed so in verification when the measured activity of ex-vessel detectors is compared with calculated ones. (authors)

  19. Effects of fluence and fluence rate of proton irradiation upon magnetism in Fe{sub 65}Ni{sub 35} Invar alloy

    Matsushita, Masafumi, E-mail: matsushita.masafumi.me@ehime-u.ac.jp [Department of Mechanical Engineering, Ehime University, 3-Bunkyocho, Matsuyama 790-8977 (Japan); Wada, Hideki [Department of Mechanical Engineering, Ehime University, 3-Bunkyocho, Matsuyama 790-8977 (Japan); Matsushima, Yasushi [Department of Physics, Okayama University, 2-naka-tsushima, Kitaku, Okayama 700-8530 (Japan)

    2015-11-15

    Curie temperature, T{sub C}, of the Fe-Ni Invar alloys increase due to irradiation with electron and some kinds of ions. In this study, proton irradiation effects upon magnetism in an Fe{sub 65}Ni{sub 35} alloy have been investigated. It is found that the increment of T{sub C,} ∆T{sub C}, increases with increasing fluence. The magnetic hysteresis curve of the alloy was found to be unaffected by irradiation. Comparing ∆T{sub C} and the calculated energy transfer from the ions to the sample, it seemed that ∆T{sub C} was found to be related to the number of vacancies formed in nuclear collision events. In addition, ∆T{sub C} was influenced by the fluence rate, i.e., the deposited energy per unit time. - Highlights: • Proton irradiation effect on T{sub C} of Fe{sub 65}Ni{sub 35} was investigated. • Increment of T{sub C}, ∆T{sub C}, was confirmed in ion passed through and stopped samples. • The relationships among ∆T{sub C} and the deposited energy and vacancies were discussed. • It was reasonable to consider that ∆T{sub C} was related to the number of vacancies. • ∆T{sub C} was influenced by fluence rate, i.e. the energy deposition rate.

  20. Improved ion implant fluence uniformity in hydrogen enhanced glow discharge plasma immersion ion implantation into silicon

    Luo, J.; Li, L. H.; Liu, H. T.; Yu, K. M.; Xu, Y.; Zuo, X. J.; Zhu, P. Z.; Ma, Y. F.; Fu, Ricky K. Y.; Chu, Paul K.

    2014-06-01

    Enhanced glow discharge plasma immersion ion implantation does not require an external plasma source but ion focusing affects the lateral ion fluence uniformity, thereby hampering its use in high-fluence hydrogen ion implantation for thin film transfer and fabrication of silicon-on-insulator. Insertion of a metal ring between the sample stage and glass chamber improves the ion uniformity and reduces the ion fluence non-uniformity as the cathode voltage is raised. Two-dimensional multiple-grid particle-in-cell simulation confirms that the variation of electric field inside the chamber leads to mitigation of the ion focusing phenomenon and the results are corroborated experimentally by hydrogen forward scattering.

  1. Evolution of InP surfaces under low fluence pulsed UV irradiation

    Musaev, O.R. [Department of Physics, University of Missouri Kansas City, Rockhill Road 5100, Kansas City, MO 64110 (United States)], E-mail: musaevo@umkc.edu; Kwon, O.S.; Wrobel, J.M.; Zhu, D.-M.; Kruger, M.B. [Department of Physics, University of Missouri Kansas City, Rockhill Road 5100, Kansas City, MO 64110 (United States)

    2008-07-15

    An InP wafer was irradiated in air by a series of UV pulses from a nitrogen laser with fluences of 120 mJ/cm{sup 2} and 80 mJ/cm{sup 2}. These fluences are below the single-pulse ablation threshold of InP. Over the studied region the distribution of the radiation intensity was uniform. The number of pulses varied from 50 to 6000. The evolution of the surface morphology and structure was characterized by atomic force microscopy, optical microscopy and Raman spectroscopy. The relationship between mound size and the number of pulses starts out following a power law, but saturates for a sufficiently high number of pulses. The crossover point is a function of fluence. A similar relation exists for the surface roughness. Raman spectroscopic investigations showed little change in local crystalline structure of the processed surface layer.

  2. Trapping and desorption of deuterium during high fluence D-implants of insulators and semiconductors

    Boergesen, P.; Moeller, W.; Maurette, M.; Monart, B.

    1986-09-01

    The trapping and desorption of deuterium during high fluence D implantation at 5 keV/atom has been investigated at room temperature in silicon, ilmenite, sapphire and 3 inorganic nuclear track detectors (oligoclase, olivine and glass). The comparison of the whole range of solids investigated as yet yields the following conclusions: (i) silicon, sapphire and ilmenite, as well as the varieties of graphite, carbide and nitride previously investigated, would behave like metals at low temperature when diffusion processes are quenched. In particular in these solids there is no reemission of D during implantation up to the critical fluence of about 5 x 10/sup 17/ D/cm/sup 2/, corresponding to the onset of a deuterium saturation. (ii) in constrast the two alkali-rich inorganic nuclear track detectors start loosing deuterium at much lower implanted fluence (approx. 10/sup 15//cm/sup 2/). A few preliminary implications of these results in lunar sciences are briefly outlined.

  3. Measurement of thermal neutron fluence rate of in-hospital neutron irradiator by SSNTD

    In-hospital neutron irradiator (IHNI) is an especially designed nuclear device based on Miniature Neutron Source Reactor (MNSR) for boron neutron capture therapy (BNCT). Its rated power is 30 kW. There are a thermal neutron beam and an epithermal neutron beam for treating patients at the opposite of the core. From the thermal neutron beam, a test beam is fetched out for measurement of boron concentration in blood by prompt γ neutron activation analysis (PGNAA) method. The neutron fluence rates at the end of thermal, epithermal and test neutron beam were measured by 235U fissile target and mica slice detector. At rated power, they are 1.67 × 109, 2.44 × 107 and 3.03 × 106 cm-2 · s-1, respectively. The results show that the thermal and epithermal neutron fluence rate can meet the requirement of BNCT and test neutron fluence rate meets the requirement of PGNAA. (authors)

  4. Fluence ablation threshold dependence on tin impurities in commercial soda-lime glass.

    Nieto, Daniel; Arines, Justo; Flores-Arias, María Teresa

    2014-08-20

    In this paper, we study the reduction in the fluence ablation threshold induced by tin impurities incorporated in float soda-lime glass during the fabrication process. The laser system used in the experiments was a Nd:YVO4 laser operating at 1064 nm with a pulse duration of 20 ns. The fluence ablation thresholds found were 112  J/cm2 for the tin side and 920  J/cm2 for the tin-free side, which means a reduction of nearly 1 order of magnitude. The fluence ablation threshold reduction permits the manufacturing of narrower grooves with small level of roughness, obtaining quality elements in low-cost soda-lime substrates. PMID:25321113

  5. Time-resolved and integrated angular distributions of plume ions from silver at low and medium laser fluence

    Christensen, Bo Toftmann; Schou, Jørgen

    2013-01-01

    Laser impact on metals in the UV regime results in a significant number of ablated plume ions even at moderate fluence (0.7–2.4 J/cm2). The ablated particles are largely neutrals at the lowest fluence, but the fraction of ions increases strongly with fluence. The ion flow in different directions...... with increasing fluence and can be well approximated by Anisimov’s model. Typically, the spectra of silver ions peak from 70 eV up to 145 eV in a direction close to the normal of the target surface with increasing fluence. With increasing observation angle, the time-of-flight spectra exhibit a peak at...... longer flight times, i.e., at a lower kinetic energy. At the highest fluence, the ionized fraction of the ablated particles in the plume increases up to 0.5....

  6. High laser-fluence deposition of organic materials in water ice matrices by ''MAPLE''

    Christensen, Bo Toftmann; Rodrigo, K.; Schou, Jørgen; Pedrys, R.

    355 nm at a fluence of 2.5-12 J/cm(2). Even at this high fluence, Fourier transform infrared spectroscopy (FTIR) indicates a chemical structure of the deposit close to that of the un-irradiated PEG. Matrix assisted laser desorption and ionization (MALDI) and gel permeation chromatography (GPC) show......Matrix assisted pulsed laser evaporation (MAPLE) is a deposition technique for organic material. Water ice was used as a matrix for the biotechnologically important guest material, polyethylene glycol (PEG), for concentrations from 0.5 to 4 wt.%. The target was irradiated with 6 ns laser pulses at...

  7. Fluence rate or cumulative dose? : Vulnerability of larval northern pike (Esox lucius) to ultraviolet radiation

    Vehniäinen, Eeva-Riikka; Häkkinen, Jani; Oikari, Aimo

    2007-01-01

    Newly hatched larvae of northern pike were exposed in the laboratory to four fluence rates of ultraviolet radiation (UVR; 290–400 nm) over three different time periods, resulting in total doses ranging from 3.0 ± 0.2 to 63.0 ± 4.4 kJ·m−2. Mortality and behavior of the larvae were followed for 8–12 days, and growth measured at the end of the experiment. Also, the principle of reciprocity—that the UVR-induced mortality depends on the cumulative dose, independent of fluence rate—was tested. Flue...

  8. Recent findings on blistering and deuterium retention in tungsten exposed to high-fluence deuterium plasma

    Blistering and deuterium retention in tungsten exposed to high-fluence (up to 1027 D/m2) of high-flux (1022 D+/m2/s) and low-energy (38 eV) deuterium plasma were examined in the temperature range of 315-1000 K with scanning electron microscopy, focused ion beam, thermal desorption spectroscopy and positron annihilation. There were cavities inside small blisters with the maximum ratio of height against diameter of about 0.7, whereas there were voids/holes along the grain boundary beneath most large blisters but no hollow lid formed. Blistering and deuterium retention showed a significant dependence upon fluence and exposure temperature.

  9. Two accurate algorithms for calculating the energy fluence profile in inverse radiation therapy planning

    Two accurate algorithms for calculating the required incident energy fluence distributions from the optimal irradiation density distribution in inverse radiation therapy planning have been developed. The algorithms are characterized by a high speed and accuracy and an ability to handle both divergent and parallel beams even for extremely heterogeneous target volumes. The fastest algorithm is based on a longitudinal distance weighting method, whereas the slower but more accurate algorithm uses an area weighting method which has the advantage that it also works very well at low spatial resolutions. Both algorithms have been inverted for forward calculation of the delivered absorbed dose distribution from known fluence profiles. (author)

  10. Minimum fluence for laser blow-off of thin gold films at 248 and 532 nm

    The minimum 248 nm, 25 ns, and 532 nm, 15 ns laser fluences required to blow off thin gold films from optical quartz have been measured as a function of film thickness. The films apparently blow off when the gold-quartz interface reaches the normal boiling point of gold. Even though the initial reflectivities at the two wavelengths are very different, the actual laser fluences required to blow off the films are very similar. While the reflectivities above the melting point appear to be very low, as expected, large decreases in the reflectivity at 532 nm may also occur prior to film melting

  11. Minimum fluence for laser blow-off of thin gold films at 248 and 532 nm

    Baseman, R.J.; Froberg, N.M.; Andreshak, J.C.; Schlesinger, Z. (IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598 (USA))

    1990-04-09

    The minimum 248 nm, 25 ns, and 532 nm, 15 ns laser fluences required to blow off thin gold films from optical quartz have been measured as a function of film thickness. The films apparently blow off when the gold-quartz interface reaches the normal boiling point of gold. Even though the initial reflectivities at the two wavelengths are very different, the actual laser fluences required to blow off the films are very similar. While the reflectivities above the melting point appear to be very low, as expected, large decreases in the reflectivity at 532 nm may also occur prior to film melting.

  12. Benchmark for a 3D Monte Carlo boiling water reactor fluence computational package - MF3D

    A detailed three dimensional model of a quadrant of an operating BWR has been developed using MCNP to calculate flux spectrum and fluence levels at various locations in the reactor system. The calculational package, MF3D, was benchmarked against test data obtained over a complete fuel cycle of the host BWR. The test package included activation wires sensitive in both the fast and thermal ranges. Comparisons between the calculational results and test data are good to within ten percent, making the MF3D package an accurate tool for neutron and gamma fluence computation in BWR pressure vessel internals. (orig.)

  13. Neutron fluence determination at reactor filters by 3He proportional counters: Comparison of unfolding algorithms

    Multichannel pulse height measurements with a cylindrical 3He proportional counter obtained at a reactor filter of natural iron are taken to investigate the properties of three algorithms for neutron spectrum unfolding. For a systematic application of uncertainty propagation the covariance matrix of previously determined 3He response functions is evaluated. The calculated filter transmission function together with a covariance matrix estimated from cross-section uncertainties of the filter material is used as fluence pre-information. The results obtained from algorithms with and without pre-information differ in shape and uncertainties for single group fluence values, but there is sufficient agreement when evaluating integrals over neutron energy intervals

  14. Multiple anatomy optimization of accumulated dose

    Purpose: To investigate the potential advantages of multiple anatomy optimization (MAO) for lung cancer radiation therapy compared to the internal target volume (ITV) approach. Methods: MAO aims to optimize a single fluence to be delivered under free-breathing conditions such that the accumulated dose meets the plan objectives, where accumulated dose is defined as the sum of deformably mapped doses computed on each phase of a single four dimensional computed tomography (4DCT) dataset. Phantom and patient simulation studies were carried out to investigate potential advantages of MAO compared to ITV planning. Through simulated delivery of the ITV- and MAO-plans, target dose variations were also investigated. Results: By optimizing the accumulated dose, MAO shows the potential to ensure dose to the moving target meets plan objectives while simultaneously reducing dose to organs at risk (OARs) compared with ITV planning. While consistently superior to the ITV approach, MAO resulted in equivalent OAR dosimetry at planning objective dose levels to within 2% volume in 14/30 plans and to within 3% volume in 19/30 plans for each lung V20, esophagus V25, and heart V30. Despite large variations in per-fraction respiratory phase weights in simulated deliveries at high dose rates (e.g., treating 4/10 phases during single fraction beams) the cumulative clinical target volume (CTV) dose after 30 fractions and per-fraction dose were constant independent of planning technique. In one case considered, however, per-phase CTV dose varied from 74% to 117% of prescription implying the level of ITV-dose heterogeneity may not be appropriate with conventional, free-breathing delivery. Conclusions: MAO incorporates 4DCT information in an optimized dose distribution and can achieve a superior plan in terms of accumulated dose to the moving target and OAR sparing compared to ITV-plans. An appropriate level of dose heterogeneity in MAO plans must be further investigated

  15. Absorbed dose in ion beams: comparison of ionisation- and fluence-based measurements

    A direct comparison measurement of fluorescent nuclear track detectors (FNTDs) and a thimble ionisation chamber is presented. Irradiations were performed using monoenergetic protons (142.66 MeV, φ=3x106 cm-2) and carbon ions (270.55 MeV u-1, φ=3x106 cm-2). It was found that absorbed dose to water values as determined by fluence measurements using FNTDs are, in case of protons, in good agreement (2.4 %) with ionisation chamber measurements, if slower protons and Helium secondaries were accounted for by an effective stopping power. For carbon, however, a significant discrepancy of 4.5 % was seen, which could not be explained by fragmentation, uncertainties or experimental design. The results rather suggest a W-value of 32.10 eV±2.6 %. Additionally, the abundance of secondary protons expected from Monte-Carlo transport simulation was not observed. FNTDs are able to yield correct dose estimation for protons. The assumption of a monoenergetic beam, even in the entrance channel, is invalid since slower protons and secondaries contribute significantly and an effective stopping power has to be employed. These corrections account for the discrepancies seen in the authors' previous experiments. Since the FNTD fluorescent track amplitude depends on the particle species and energy, the effective stopping power might be estimated from the intensity histogram of the particle tracks. For carbon ions, however, secondary particles did not fully account for the discrepancies found. Considering the detection efficiency of FNTD technology, it seems unlikely that a significant portion of tracks were not registered. This might stimulate discussions on the accuracy of the kQ,Q0 factor for carbon beams. Since the stopping power in this energy range is known quite accurately (1-2 %), one might question the currently used constant Wair value of 34.50 ± 0.52 eV (1.5 %)(14). The presented findings would imply a Wair value of 32.10±0.83 eV (2.6 %). This uncertainty includes all

  16. Environmental effects on 222Rn fluence rate from reclaimed uranium mill tailings

    The author measured 222Rn fluence rate from 2 plots with uranium mill tailings buried beneath 30 cm of overburden and 30 cm of topsoil. An additional 30 cm of clay covered the tailings on 1 of the plots and each plot was subdivided into bare soil and vegetated subplots. The author also measured a control plot, identical to the plot without a clay cap but having no tailings. In addition to fluence rate, The author measured moisture in each of the plot layers, atmospheric pressure, air temperature and relative humidity during each sampling period. The author used linear correlation, two-way ANOVA and stepwise multiple regression to analyze the effects of the plot characteristics and the environmental variables on 222Rn fluence rate. The mean fluence rate from the plot having both a clay cap and a vegetated surface was over 3 times that of the vegetated plot without a clay cap and 14 times that of the bare plot with a clay cap. The interaction effect may be due to the proliferation of roots in the moist clay and active transport of dissolved 222Rn to the surface in water

  17. New method for estimation of fluence complexity in IMRT fields and correlation with gamma analysis

    A new method for estimation of fluence complexity in Intensity Modulated Radiation Therapy (IMRT) fields is proposed. Unlike other previously published works, it is based on portal images calculated by the Portal Dose Calculation algorithm in Eclipse (version 8.6, Varian Medical Systems) in the plane of the EPID aS500 detector (Varian Medical Systems). Fluence complexity is given by the number and the amplitudes of dose gradients in these matrices. Our method is validated using a set of clinical plans where fluence has been smoothed manually so that each plan has a different level of complexity. Fluence complexity calculated with our tool is in accordance with the different levels of smoothing as well as results of gamma analysis, when calculated and measured dose matrices are compared. Thus, it is possible to estimate plan complexity before carrying out the measurement. If appropriate thresholds are determined which would distinguish between acceptably and overly modulated plans, this might save time in the re-planning and re-measuring process

  18. 39Ar as a probe of the fast-neutron fluence of the Hiroshima atomic bomb

    A new method to estimate the fast-neutron fluence of the Hiroshima atomic bomb is proposed. Recent studies on the thermal-neutron fluence of the Hiroshima atomic bomb have suggested a systematic discrepancy from DS86. On the other hand most of the neutron dose for human was due to fast-neutrons, which is a basis of the radiation-risk estimation. Therefore, a direct measurement of the fast-neutron fluence has been required. This paper points out that the 39Ar produced by the 39K(n,p)39Ar reaction would be a unique probe to estimate the fast-neutron fluence of the atomic bomb. This is because the half life of 39Ar is 269 years, which is sufficiently long to exist for a period of 50 years after the explosion, and the threshold of the 39K(n,p)39Ar reaction is 1 MeV. The feasibility of the 39Ar method is discussed in this report. (author)

  19. Evaluation of the Fluence Conversion Factor for 32P in Sulfur

    Wong, C. T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-03-18

    When 32S is exposed to neutrons it undergoes a 32S(n,p)32P reaction with a neutron cross section as shown in Figure 1. This reaction may be used to characterize the neutron fluence for neutrons greater than 3 MeV.

  20. Calculation of fluence and absorbed dose in head tissues due to different photon energies

    Calculations of fluence and absorbed dose in head tissues due to different photon energies were carried out using the MCNPX code, to simulate two models of a patient's head: one spherical and another more realistic ellipsoidal. Both head models had concentric shells to describe the scalp skin, the cranium and the brain. The tumor was located at the center of the head and it was a 1 cm-radius sphere. The MCNPX code was run for different energies. Results showed that the fluence decreases as the photons pass through the different head tissues. It can be observed that, although the fluence into the tumor is different for both head models, absorbed dose is the same. - Highlights: • A Monte Carlo algorithm to simulate the passage of photons through a homogeneous material was developed. • Two models of a patient's head, one spherical and another more realistic ellipsoidal model, were simulated using the Monte Carlo code. • The fluence into the tumor is different for both head models, but absorbed dose in the tumor is the same

  1. High-accuracy fluence determination in ion beams using fluorescent nuclear track detectors

    Osinga, J.-M.; Akselrod, M.S.; Herrmann, Rochus;

    2013-01-01

    We present an approach to use Al2O3:C,Mg-based fluorescent nuclear track detectors (FNTDs) and confocal laser scanning microscopy as a semiautomatic tool for fluence measurements in clinical ion beams. The method was found to cover a linear energy transfer (LET) range from at least L∞(Al2O3) = 0...

  2. Measurements of thermal neutron fluence proton therapy for head and neck

    We present an estimate of the distribution of thermal neutron fluence proton therapy for head and neck using an anthropomorphic phantom called NORMA. It also represents a small part within a larger project which aims to develop a risk prediction model due to neutron radiation generated indirectly in radiotherapy.

  3. Low-intensity red and infrared laser effects at high fluences on Escherichia coli cultures

    Barboza, L.L.; Campos, V.M.A.; Magalhaes, L.A.G. [Instituto de Biologia Roberto Alcantara Gomes, Rio de Janeiro, RJ (Brazil). Departamento de Biofisica e Biometria; Paoli, F. [Universidade Federal de Juiz de Fora (UFJF), Juiz de Fora, MG (Brazil). Departamento de Morfologia; Fonseca, A.S., E-mail: adnfonseca@ig.com.br [Universidade Federal do Estado do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Departamento de Ciencias Fisiologicas

    2015-10-15

    Semiconductor laser devices are readily available and practical radiation sources providing wavelength tenability and high monochromaticity. Low-intensity red and near-infrared lasers are considered safe for use in clinical applications. However, adverse effects can occur via free radical generation, and the biological effects of these lasers from unusually high fluences or high doses have not yet been evaluated. Here, we evaluated the survival, filamentation induction and morphology of Escherichia coli cells deficient in repair of oxidative DNA lesions when exposed to low-intensity red and infrared lasers at unusually high fluences. Cultures of wild-type (AB1157), endonuclease III-deficient (JW1625-1), and endonuclease IV-deficient (JW2146-1) E. coli, in exponential and stationary growth phases, were exposed to red and infrared lasers (0, 250, 500, and 1000 J/cm{sup 2}) to evaluate their survival rates, filamentation phenotype induction and cell morphologies. The results showed that low-intensity red and infrared lasers at high fluences are lethal, induce a filamentation phenotype, and alter the morphology of the E. coli cells. Low-intensity red and infrared lasers have potential to induce adverse effects on cells, whether used at unusually high fluences, or at high doses. Hence, there is a need to reinforce the importance of accurate dosimetry in therapeutic protocols. (author)

  4. Determination of fluence-to-dose conversion coefficients by means of artificial neural networks

    In this paper is presented an Artificial Neural Network (Ann) that has been designed, trained and validated to determinate the effective dose e, ambient dose equivalent h(10) and personal dose equivalent hp(10,θ) fluence-to-dose conversion coefficients at different positions, having as only input data 7 count rates obtained with a Bonner Sphere Spectrometer (Bss) system. A set of 211 neutron spectra and the fluence-to-dose conversion coefficients published by the International Atomic Energy Agency were used to train and validate the Ann. This set was divided into 2 subsets, one of 181 elements to train the Ann and the remaining 30 to validate it. The Ann was trained using Bss count rates as input data and the fluence-to-dose conversion coefficients as output data. The network was validated and tested with the set of 30 elements that were not used during the training process. Good results were obtained proving that Ann are a good choice for calculating the fluence-to-dose conversion coefficients having as only data the count rates obtained with a Bss. (Author)

  5. Corrosion behaviors of Mo coating on stainless steel 316 substrates implanted by different nitrogen ion fluences

    Mojtahedzadeh Larijani, Madjid; Bafandeh, Nastaran

    2014-03-01

    The molybdenum nitride coating was produced by nitrogen ion implantation of the molybdenum layer deposited on the stainless steel 316 (SS) substrates. At first, molybdenum layers were deposited on the substrates by ion beam sputtering method, then nitrogen ions with an energy of 30 keV and a fluence between 1×1017 and 12×1017 N+ cm-2 were implanted in Mo/SS system. Crystal structure and topography of the surface are investigated by grazing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM) image respectively. XRD patterns showed the formation of molybdenum nitride phases in all implanted samples. Corrosion tests showed that the corrosion resistance of the samples strongly depends on the nitrogen applied fluences. A considerable improvement of corrosion performance by increasing ions fluences was observed. The lowest corrosion current density with amount of 0.1 μA/cm2 was obtained at 12×1017 ions/cm2 fluence in our case.

  6. Irradiation change of graphite properties in a wide range of temperatures and neutron fluences

    Dose dependences of radiation changes of graphite properties in a wide temperature range (70-800 deg C) are built on the basis of experimental data. Presented are the dependences of relative changes in crystal lattice parameter, sample sizes, strength limit, elasticity module and electrical resistance on the neutron fluence

  7. Estimation of thermal neutron fluences in the concrete of proton accelerator facilities from 36Cl production

    Bessho, K.; Matsumura, H.; Miura, T.; Wang, Q.; Masumoto, K.; Hagura, H.; Nagashima, Y.; Seki, R.; Takahashi, T.; Sasa, K.; Sueki, K.; Matsuhiro, T.; Tosaki, Y.

    2007-06-01

    The thermal neutron fluence that poured into the shielding concrete of proton accelerator facilities was estimated from the in situ production of 36Cl. The thermal neutron fluences at concrete surfaces during 10-30 years of operation were in the range of 1012-1014 n/cm2. The maxima in thermal neutron fluences were observed at ≈5-15 cm in the depths analyzed for 36Cl/35Cl by AMS. These characteristics imply that thermalization of neutrons occurred inside the concrete. Compared to the several tens of MeV cyclotrons, secondary neutrons penetrate deeper into the concrete at the high-energy accelerators possessing acceleration energies of 400 MeV and 12 GeV. The attenuation length of neutrons reflects the energy spectra of secondary neutrons emitted by the nuclear reaction at the beam-loss points. Increasing the energy of secondary neutrons shifts the maximum in the thermal neutron fluences to deeper positions. The data obtained in this study will be useful for the radioactive waste management at accelerator facilities.

  8. Effect of Net-Fluence on waveguide formation in ultrafast laser inscribed chalcogenide glass

    Sabapathy, Tamilarasan; Sivakumar, Gayathri; Ayiriveetil, Arunbabu; Ajoy K. Kar; Asokan, Sundarrajan

    2012-01-01

    Waveguides were fabricated on GeGaSEr chalcogenide glass using ultrafast laser inscription method. The thermal diffusion model is discussed for understanding the light matter interaction and shown the effect of net-fluence in waveguide formation on chalcogenide glass. (C) 2012 Optical Society of America

  9. Estimates of energy fluence at the focal plane in beams undergoing neutralized drift compression

    The authors estimate the energy fluence (energy per unit area) at the focal plane of a beam undergoing neutralized drift compression and neutralized solenoidal final focus, as is being carried out in the Neutralized Drift Compression Experiment (NDCX) at LBNL. In these experiments, in order to reach high beam intensity, the beam is compressed longitudinally by ramping the beam velocity (i.e. introducing a velocity tilt) over the course of the pulse, and the beam is transversely focused in a high field solenoid just before the target. To remove the effects of space charge, the beam drifts in a plasma. The tilt introduces chromatic aberrations, with different slices of the original beam having different radii at the focal plane. The fluence can be calculated by summing the contribution from the various slices. They develop analytic formulae for the energy fluence for beams that have current profiles that are initially constant in time. They compare with envelope and particle-in-cell calculations. The expressions derived are useful for predicting how the fluence scales with accelerator and beam parameters

  10. Estimation of thermal neutron fluences in the concrete of proton accelerator facilities from 36Cl production

    The thermal neutron fluence that poured into the shielding concrete of proton accelerator facilities was estimated from the in situ production of 36Cl. The thermal neutron fluences at concrete surfaces during 10-30 years of operation were in the range of 1012-1014 n/cm2. The maxima in thermal neutron fluences were observed at ∼5-15 cm in the depths analyzed for 36Cl/35Cl by AMS. These characteristics imply that thermalization of neutrons occurred inside the concrete. Compared to the several tens of MeV cyclotrons, secondary neutrons penetrate deeper into the concrete at the high-energy accelerators possessing acceleration energies of 400 MeV and 12 GeV. The attenuation length of neutrons reflects the energy spectra of secondary neutrons emitted by the nuclear reaction at the beam-loss points. Increasing the energy of secondary neutrons shifts the maximum in the thermal neutron fluences to deeper positions. The data obtained in this study will be useful for the radioactive waste management at accelerator facilities

  11. The importance of fluence rate in photodynamic therapy: is there a parallel with ionizing radiation dose-rate effects?

    Several similarities can be found between dose-rate effects in radiotherapy and fluence-rate effects in photodynamic therapy (PDT). At low dose rates repair of sublethal damage can occur, whereas at high dose rates oxygen depletion can decrease the effects of both therapies. The available literature for fluence-rate effects in PDT is discussed here in relation to therapeutic implications

  12. Red light-induced shift of the fluence-response curve for first positive curvature of maize [Zea mays] coleoptiles

    The fluence-response curve for first positive phototropic curvture of dark-grown maize coleoptiles is shifted to ten-fold higher fluences if the coieoptiles are irradiated with red light 2 h prior to the phototropic induction with blue light. Fluence-response curves for this red-induced shift were obtained with unilateral red irradiations 2 h prior to inductive blue pulses of different fluences. They differ significantly depending on whether the red light was given from the same side as or the opposite side to the respective inductive blue pulse, thus demonstrating that the red light effect is a local response of the coleoptile. The fluence-response curves for an inductive blue pulse in the ascending part were compared with those for an inductive blue pulse in the descending part of the fluence-response curve for blue light induced phototropism. They are quite different in threshold of red light sensitivity and shape for irradiations from both the same and the opposite sides. This offers evidence for the hypothesis that at least two different photosystems are involved in phototropism, and that they are modulated differently by a red light preirradiation. All these fluence-response curves indicate that it is possible to increase the response in the coleoptile, if the red light preirradiation is given opposite to the inductive blue pulse. This is supported by blue light fluence-response curves obtained after a weak unilateral red preirradiation. (author)

  13. Atomistic simulation of damage accumulation and amorphization in Ge

    Gomez-Selles, Jose L., E-mail: joseluis.gomezselles@imdea.org; Martin-Bragado, Ignacio [IMDEA Materials Institute, Eric Kandel 2, 28906 Getafe, Madrid (Spain); Claverie, Alain [CEMES/CNRS, 29 rue J. Marvig, 31055 Toulouse Cedex (France); Sklenard, Benoit [CEA, LETI, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Benistant, Francis [GLOBALFOUNDRIES Singapore Pte Ltd., 60 Woodlands Industrial Park D Street 2, Singapore 738406 (Singapore)

    2015-02-07

    Damage accumulation and amorphization mechanisms by means of ion implantation in Ge are studied using Kinetic Monte Carlo and Binary Collision Approximation techniques. Such mechanisms are investigated through different stages of damage accumulation taking place in the implantation process: from point defect generation and cluster formation up to full amorphization of Ge layers. We propose a damage concentration amorphization threshold for Ge of ∼1.3 × 10{sup 22} cm{sup −3} which is independent on the implantation conditions. Recombination energy barriers depending on amorphous pocket sizes are provided. This leads to an explanation of the reported distinct behavior of the damage generated by different ions. We have also observed that the dissolution of clusters plays an important role for relatively high temperatures and fluences. The model is able to explain and predict different damage generation regimes, amount of generated damage, and extension of amorphous layers in Ge for different ions and implantation conditions.

  14. Atomistic simulation of damage accumulation and amorphization in Ge

    Damage accumulation and amorphization mechanisms by means of ion implantation in Ge are studied using Kinetic Monte Carlo and Binary Collision Approximation techniques. Such mechanisms are investigated through different stages of damage accumulation taking place in the implantation process: from point defect generation and cluster formation up to full amorphization of Ge layers. We propose a damage concentration amorphization threshold for Ge of ∼1.3 × 1022 cm−3 which is independent on the implantation conditions. Recombination energy barriers depending on amorphous pocket sizes are provided. This leads to an explanation of the reported distinct behavior of the damage generated by different ions. We have also observed that the dissolution of clusters plays an important role for relatively high temperatures and fluences. The model is able to explain and predict different damage generation regimes, amount of generated damage, and extension of amorphous layers in Ge for different ions and implantation conditions

  15. STC Germany/Russia. Fluence calculations of surveillance specimens of the VVER-440. Final report; WTZ Russland. Fluenzberechnungen fuer Voreilproben beim WWER-440. Abschlussbericht

    Konheiser, J.; Grahn, A.

    2014-07-01

    Reactor pressure vessels (RPV) are non-restorable equipment and their lifetime may restrict the nuclear power plant-life as a whole. Surveillance specimen programs for RPV materials are among the most important measures of in-service inspection programs that are necessary for realistic and reliable assessment of the RPV residual lifetime. In addition to the chemical composition of the RPV steel, the radiation parameters (neutron and gamma fluences and spectra) have the most important impact on the RPV embrittlement characteristics. In this work, different geometric positions which have influence on the radiation conditions of the samples are investigated. Thus, the uncertainties can be determined in the fluence values of surveillance specimens. The fluence calculations were carried out by the codes TRAMO and DORT. This study was accompanied by ex-vessel neutron dosimetry experiments at Kola NPP, Unit 3 (VVER-440/213), which provide the basis for validation of calculated neutron fluences. The main neutron-activation monitoring reactions were {sup 54}Fe(n,p){sup 54}Mn and {sup 58}Ni(n,p){sup 58}Co. The activity measurements were carried out by ''Scientific and Engineering Centre for Nuclear and Radiation Safety (SEC NRS). Good agreement between the deterministic and stochastic calculation results as well as between the calculations and the ex-vessel measurements was found. The average difference between measured and calculated values is 5%. The influence of the channels for surveillance specimens and the shielding effect of a baffle rib on the monitors and on the Monte-Carlo calculated results was studied. For the surveillance specimens in the maximum of the flux, an average flux of around 2.45 * 10{sup 12} neutrons/cm{sup 2} was calculated for the neutron flux E> 0.5 MeV. The differences in the surveillance specimens could be up to 20% depending on the direction to the core. Discrepancies up to 10% can be caused by the change of the position of the

  16. Pulsed laser ablation of Germanium under vacuum and hydrogen environments at various fluences

    Iqbal, Muhammad Hassan [Centre for Advanced Studies in Physics, Government College University, Lahore (Pakistan); Bashir, Shazia, E-mail: shaziabashir@gcu.edu.pk [Centre for Advanced Studies in Physics, Government College University, Lahore (Pakistan); Rafique, Muhammad Shahid [Department of Physics, University of Engineering and Technology, Lahore (Pakistan); Dawood, Asadullah; Akram, Mahreen; Mahmood, Khaliq; Hayat, Asma; Ahmad, Riaz; Hussain, Tousif [Centre for Advanced Studies in Physics, Government College University, Lahore (Pakistan); Mahmood, Arshad [National Institute of Laser and Optronics (NILOP), Islamabad (Pakistan)

    2015-07-30

    Highlights: • Germanium targets were exposed under vacuum and H{sub 2} environment by nanosecond laser pulses. • The effect of laser fluence and ambient environment has been investigated. • The surface morphology is investigated by SEM analysis. • Raman and FTIR Spectroscopy are performed to reveal structural modification. • Electrical conductivity is probed by four probe method. - Abstract: Laser fluence and ambient environment play a significant role for the formation and development of the micro/nano-structures on the laser irradiated targets. Single crystal (1 0 0) Germanium (Ge) has been ablated under two environments of vacuum (10{sup −3} Torr) and hydrogen (100 Torr) at various fluences ranging from 4.5 J cm{sup −2} to 6 J cm{sup −2}. For this purpose KrF Excimer laser with wavelength of 248 nm, pulse duration of 18 ns and repetition rate of 20 Hz has been employed. Surface morphology has been observed by Scanning Electron Microscope (SEM). Whereas, structural modification of irradiated targets was explored by Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy. Electrical conductivity of the irradiated Ge is measured by four probe method. SEM analysis exhibits the formation of laser-induced periodic surface structures (LIPSS), cones and micro-bumps in both ambient environments (vacuum and hydrogen). The formation as well as development of these structures is strongly dependent upon the laser fluence and environmental conditions. The periodicity of LIPSS or ripples varies from 38 μm to 60 μm in case of vacuum whereas in case of hydrogen environment, the periodicity varies from 20 μm to 45 μm. The difference in number of ripples and periodicity as well as in shape and size of cones and bumps in vacuum and hydrogen is explained on the basis of confinement and shielding effect of plasma. FTIR spectroscopy reveals that no new bands are formed for laser ablated Ge under vacuum, whereas C−H stretching vibration band is

  17. Pulsed laser ablation of Germanium under vacuum and hydrogen environments at various fluences

    Highlights: • Germanium targets were exposed under vacuum and H2 environment by nanosecond laser pulses. • The effect of laser fluence and ambient environment has been investigated. • The surface morphology is investigated by SEM analysis. • Raman and FTIR Spectroscopy are performed to reveal structural modification. • Electrical conductivity is probed by four probe method. - Abstract: Laser fluence and ambient environment play a significant role for the formation and development of the micro/nano-structures on the laser irradiated targets. Single crystal (1 0 0) Germanium (Ge) has been ablated under two environments of vacuum (10−3 Torr) and hydrogen (100 Torr) at various fluences ranging from 4.5 J cm−2 to 6 J cm−2. For this purpose KrF Excimer laser with wavelength of 248 nm, pulse duration of 18 ns and repetition rate of 20 Hz has been employed. Surface morphology has been observed by Scanning Electron Microscope (SEM). Whereas, structural modification of irradiated targets was explored by Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy. Electrical conductivity of the irradiated Ge is measured by four probe method. SEM analysis exhibits the formation of laser-induced periodic surface structures (LIPSS), cones and micro-bumps in both ambient environments (vacuum and hydrogen). The formation as well as development of these structures is strongly dependent upon the laser fluence and environmental conditions. The periodicity of LIPSS or ripples varies from 38 μm to 60 μm in case of vacuum whereas in case of hydrogen environment, the periodicity varies from 20 μm to 45 μm. The difference in number of ripples and periodicity as well as in shape and size of cones and bumps in vacuum and hydrogen is explained on the basis of confinement and shielding effect of plasma. FTIR spectroscopy reveals that no new bands are formed for laser ablated Ge under vacuum, whereas C−H stretching vibration band is formed for two moderate

  18. IR multiphoton absorption of SF6 in flow with Ar at moderate energy fluences

    Makarov, G. N.; Ronander, E.; van Heerden, S. P.; Gouws, M.; van der Merwe, K.

    1997-10-01

    IR multiple photon absorption (MPA) of SF6 in flow with Ar (SF6: Ar=1:100) in conditions of a large vibrational/rotational temperature difference (TV𪒮 K, TR䏐 K) was studied at moderate energy fluences from ۂ.1 to 𪐬 mJ/cm2, which are of interest for isotope selective two-step dissociation of molecules. A 50 cm Laval-type slit nozzle for the flow cooling, and a TEA CO2-laser for excitation of molecules were used in the experiments. The laser energy fluence dependences of the SF6 MPA were studied for several CO2-laser lines which are in a good resonance with the linear absorption spectrum of the Ƚ vibration of SF6 at low temperature. The effect of the laser pulse duration (intensity) on MPA of flow cooled SF6 with Ar was also studied. The results are compared with those obtained in earlier studies.

  19. A study of neutron fluence rates of the BNCT beam at THOR using foil activation

    Neutron fluence rates of the BNCT epithermal neutron beam at THOR were measured by using double-foil activation method free-in-air and in a water phantom. Foil sets consisting of gold, copper and manganese were used for measurements. Copper was used as an extra detector for quality check. Monte Carlo calculations using the MCNP4C code were conducted to support and compare with the measurement results. It was found that the calculation of reaction rates of foils free-in-air based on a neutron source with a coarse group energy structure is inadequate. The meetness of the assumptions on the neutron energy distribution made in the double-foil formulation for the determination of neutron fluence rates must be estimated in order to compare with the calculation. (author)

  20. A Method to Estimate the Fast-Neutron Fluence for the Hiroshima Atomic Bomb

    Shibata, Tokushi; Imamura, Mineo; Shibata, Seiichi; Uwamino, Yoshitomo; Ohkubo, Tohru; Satoh, Shinngo; Nogawa, Norio; Hasai, Hiromi; Shizuma, Kiyoshi; Iwatani, Kazuo; Hoshi, Masaharu; Oka, Takamitsu

    1994-10-01

    A new method to estimate the fast-neutron fluence of the Hiroshima atomic bomb is proposed. 63Ni produced by the 63Cu(n, p)63Ni reaction provides a unique measure by which to estimate the fast-neutron fluence of the Hiroshima/Nagasaki atomic bombs, because the half-life of 63Ni is 100 years and 70% of the 63Ni produced in a copper piece presently exists after 50 years. Using the neutron spectrum given in DS86 and the estimated cross section, we found that a piece of copper of about 10 g which was exposed at a point around 100 m from the hypocenter gives a measurable amount of 63Ni using a low-background liquid scintillation counter. For the measurement of 63Ni, accelerator mass spectrometry also seems to be applicable.

  1. Neutron fluence at the pressure vessel of a pressurized water reactor determined by the MCNP code

    Pressure vessel fluence and reaction rates for dosimetry foils in the cavity surrounding the pressure vessel of a pressurized water reactor were determined with a Monte Carlo calculation using the MCNP code. Source neutrons were sampled from a position probability distribution derived from the utility-provided normalized assembly segment power output. The MCNP model was based on one-eighth core symmetry. Source segment spatial biasing, energy cutoff, spatial importance functions, and weight windows were employed as variance reduction techniques. Computed reaction rates were compared with measured ones and in one case to discrete ordinates transport code calculations. Computed reaction rates matched the measured ones within ±10% for 21 of 33 cases and within ±15% for 26 of 33 cases. Neutron flux and fluence >0.1111 and 1 MeV at the pressure vessel location were computed to 17 n/cm2

  2. Isotope separation by laser ablation. Dependence of selectivity on laser fluence

    In a process of isotope separation by infrared laser ablation, a Kr matrix which contains guest molecules of SF6 (32SF6 : 34SF6 = 95.02 : 4.2) is irradiated with a pulse from a TEA CO2 laser to excite 32SF6(10P(30)) or 34SF6(10P(48)) selectively. It is proved that in the case of exciting 32SF6 the excited species of 32SF6 is less emitted from the matrix than non excited 34SF6 is. The dependence of selectivity (or separation factor) on laser fluence was examined for a range of 20-80 mJ/cm2. The optimum value of fluence is around 30 mJ/cm2. (author)

  3. High fluence ion beam modification of polymer surfaces: EPR and XPS studies

    Polyethylene, polyamide-6 and polyimide foils implanted with 100 keV B+, P+ and Sb+ ions to a fluence range of 1015-1017 cm-2 have been studied using the electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) methods. The experimental data allow the comparison of the implantation-induced changes both in a given polymer foil under different ion beam regimes and in different polymers under similar ion-bombardment conditions. The high fluence implantation of boron ions, depositing energy mainly via electronic stopping, was found to be accompanied with the effective formation of π-bonded carbon-rich clusters. By contrast, heavier (phosphorus and antimony) ions, which deposit energy predominantly in nuclear collisions, produced a lower concentration of π-radicals and a less carbonised top surface layer. The peculiarities and main trends of the alterations of the polymer structure and composition induced via electronic and nuclear stopping have also been discussed

  4. High fluence ion beam modification of polymer surfaces: EPR and XPS studies

    Popok, V. N.; Azarko, I. I.; Odzhaev, V. B.; Tóth, A.; Khaibullin, R. I.

    2001-05-01

    Polyethylene, polyamide-6 and polyimide foils implanted with 100 keV B+, P+ and Sb + ions to a fluence range of 10 15-10 17 cm-2 have been studied using the electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) methods. The experimental data allow the comparison of the implantation-induced changes both in a given polymer foil under different ion beam regimes and in different polymers under similar ion-bombardment conditions. The high fluence implantation of boron ions, depositing energy mainly via electronic stopping, was found to be accompanied with the effective formation of π-bonded carbon-rich clusters. By contrast, heavier (phosphorus and antimony) ions, which deposit energy predominantly in nuclear collisions, produced a lower concentration of π-radicals and a less carbonised top surface layer. The peculiarities and main trends of the alterations of the polymer structure and composition induced via electronic and nuclear stopping have also been discussed.

  5. Method of tallying adjoint fluence and calculating kinetics parameters in Monte Carlo codes

    A method of using iterated fission probability to estimate the adjoint fluence during particles simulation, and using it as the weighting function to calculate kinetics parameters βeff and A in Monte Carlo codes, was introduced in this paper. Implements of this method in continuous energy Monte Carlo code MCNP and multi-group Monte Carlo code MCMG are both elaborated. Verification results show that, with regardless additional computing cost, using this method, the adjoint fluence accounted by MCMG matches well with the result computed by ANISN, and the kinetics parameters calculated by MCNP agree very well with benchmarks. This method is proved to be reliable, and the function of calculating kinetics parameters in Monte Carlo codes is carried out effectively, which could be the basement for Monte Carlo codes' utility in the analysis of nuclear reactors' transient behavior. (authors)

  6. Irradiation creep in bending of cold-worked AISI 316 stainless steel at low neutron fluence

    The results from the first and second interim examinations of a test to measure irradiation creep in bending of 20 percent cold-worked AISI 316 stainless steel are presented. These low-fluence results indicate that irradiation creep in bending exhibits a larger primary creep component of the total strain as compared with creep in biaxial pressurized tubes of the same heat of material, but the secondary creep rates in the two cases appear to be similar. The data also indicate that the bending strains have a linear fluence and stress dependency, and strains measured on beams fabricated parallel to and transverse to the direction of cold work are similar, indicating that material texture anisotropy does not effect irradiation creep in bending. 6 refs

  7. Spatial fluence profile for certification test of laser damage resistance: Call for comments

    This paper presents a technique for certifying the laser power handling capability of a laser optic. This paper is being presented so that community comments can be collected and incorporated before the issuance of a draft international standard based in the technique defined in the paper in 1997. The paper derives the curve for the probability of the optic surviving a series of exposures to laser irradiation as a function of the laser fluence (power) profile, the number of damage initiation sites on the optic and the fraction of the test optic irradiated at or above a specific level. Of general interest to the community is the discussion of the proper fluence profile for the certification test

  8. A method to estimate the fast-neutron fluence for the Hiroshima atomic bomb

    A new method to estimate the fast-neutron fluence of the Hiroshima atomic bomb is proposed. 63Ni produced by the 63Cu(n, p)63Ni reaction provides a unique measure by which to estimate the fast-neutron fluence of the Hiroshima/Nagasaki atomic bombs, because the half-life of 63Ni is 100 years and 70% of the 63Ni produced in a copper piece presently exists after 50 years. Using the neutron spectrum given in DS86 and the estimated cross section, we found that a piece of copper of about 10 g which was exposed at a point around 100 m from the hypocenter gives a measurable amount of 63Ni using a low-background liquid scintillation counter. For the measurement of 63Ni, accelerator mass spectrometry also seems to be applicable. (author)

  9. An altitude and distance correction to the source fluence distribution of TGFs

    Nisi, R S; Gjesteland, T; Collier, A B

    2016-01-01

    The source fluence distribution of terrestrial gamma ray flashes (TGFs) has been extensively discussed in recent years, but few have considered how the TGF fluence distribution at the source, as estimated from satellite measurements, depends on the distance from satellite foot point and assumed production altitude. As the absorption of the TGF photons increases significantly with lower source altitude and larger distance between the source and the observing satellite, these might be important factors. We have addressed the issue by using the tropopause pressure distribution as an approximation of the TGF production altitude distribution and World Wide Lightning Location Network spheric measurements to determine the distance. The study is made possible by the increased number of Ramaty High Energy Solar Spectroscopic Imager (RHESSI) TGFs found in the second catalog of the RHESSI data. One find is that the TGF/lightning ratio for the tropics probably has an annual variability due to an annual variability in the...

  10. Study on measurement technique contrast of 14 MeV neutron fluence

    The stability and repetition of the associated-particle method to measure DT neutron fluence was tested. The neutron activation iron method was contrasted with the associated-particle method, the preparatory experiment was done. The neutron fluence measured with associated-particle method was contrasted with neutron activation Al method, the Al activated foil was measured with 4πβ (PC)-γ coincidence standard device. The contrast result's standard deviation of the two method was less than the expand uncertainty of the associated-particle method. Therein, the uncertainty of the associated-particle method is 1.6%, the uncertainty of the activation Al method is 1.8%. (authors)

  11. Pain during photodynamic therapy is associated with protoporphyrin IX fluorescence and fluence rate

    Wiegell, S.R.; Skiveren, J.; Philipsen, P.A.;

    2008-01-01

    protoporphyrin IX (PpIX) fluorescence, lesion type, lesion preparation and lesion localization. Methods Twenty-six patients with actinic keratoses (AKs) in different localizations and 34 patients with facial acne vulgaris were treated with methyl aminolaevulinate-PDT. Patients with acne were illuminated using......) patients with acne had a pain score of 6 [interquartile range (IQR) 5-7] compared with 8 (IQR 6-10) when using a fluence rate of 68 mW cm(-2) (P = 0.018). After correcting the pain score for PpIX fluorescence no differences in pain scores were found between first and second acne treatment, locations of AK...... lesions or between the two types of lesions. Conclusions Pain during PDT was correlated with the PpIX fluorescence in the treatment area prior to illumination. Pain was reduced using a lower fluence rate during PDT of acne Udgivelsesdato: 2008/4...

  12. Hole mobility in germanium irradiated with large fluences of fast neutrons

    The Hall mobility of holes in germanium irradiated with large fluences of fast neutrons 1014 cm-219 cm-2 is studied over a wide range of temperature 7 K14 cm-3RD17 cm-3. After irradiation the original samples became p-type, low-resistance samples. Electrical properties of neutron irradiated germanium are determined by acceptor-like radiation defects with energy levels of EV+0.016 eV. It is found that at temperatures above 100 K the hole mobility in neutron irradiated germanium and in germanium doped by gallium changes with temperature by general laws, and their values are comparable. The main scattering mechanisms inherent to homogeneous doped crystalline semiconductors are established also in neutron irradiated germanium. The results give rise to conclude that germanium irradiated with large fluences of fast neutrons can be assumed as crystalline with a homogeneous radiation defect distribution. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  13. Fast neutron fluences determination for Khmelnitskaya NPP Unit 1 surveillance specimens

    Fast neutron fluences on surveillance specimens of Khmelnitskaya NPP Unit 1 were determined by results of measurements of neutron-activation indicators accompanied surveillance specimens irradiation. It was shown that reliable transfer of results from surveillance specimens to reactor pressure vessel is impossible and for this purpose, it is necessary to determine space-energy characteristics not only for surveillance specimens locations but for reactor pressure vessel also

  14. Evaluation of fluence to dose equivalent conversion factors for high energy radiations, (1)

    Computer code system and basic data have been investigated for evaluating fluence to dose equivalent conversion factors for photons and neutrons up to 10 GeV. The present work suggested that the conversion factors would be obtained by incorporating effective quality factors of charged particles into the HERMES (High Energy Radiation Monte Carlo Elaborate System) code system. The effective quality factors for charged particles were calculated on the basis of the Q-L relationships specified in the ICRP Publication-60. (author)

  15. Low fluence rate photodynamic therapy combined with intravitreal bevacizumab for neovascular age related macular degeneration.

    Costagliola, Ciro; Romano, Mario R.; Rinaldi, Michele; Dell'Omo, Robeto; Chiosi, Flavia; Menzione, Massimo; Semeraro, Francesco

    2010-01-01

    Abstract Aims: to report efficacy and safety of intravitreal bevacizumab (IVB) alone versus IVB plus low fluence PDT in age-related macular degeneration (AMD) patients and to verify the occurrence of a synergistic effect of the combined approach on visual acuity, size and morphology of lesion, as well as on the treatment rate. Method: prospective comparative interventional study on 85 patients with treatment naive classic, or predominantly classic, subfoveal choroid...

  16. Low-fluence femtosecond-laser interaction with a Mo/Si multilayer stack

    Hoeche, T. [3D-Micromac AG, Max-Planck-Strasse 22b, 09114, Chemnitz (Germany); Leibniz-Institut fuer Oberflaechenmodifizierung e.V., Permoserstrasse 15, 04318, Leipzig (Germany); Ruthe, D. [Leibniz-Institut fuer Oberflaechenmodifizierung e.V., Permoserstrasse 15, 04318, Leipzig (Germany); Petsch, T. [3D-Micromac AG, Max-Planck-Strasse 22b, 09114, Chemnitz (Germany)

    2004-09-01

    Nanostructural damage caused by low-fluence, non-ablating femtosecond laser irradiation of Mo/Si multilayer stacks is studied by cross-sectional transmission electron microscopy. A laterally homogeneous modification of the multilayer structure is observed including a complete intermixing of silicon and molybdenum in the depth range between 0 and 20 nm. Below this amorphous layer, molybdenum layers become more and more stable until below 80 nm depth, the pristine microstructure of the non-processed multilayer is observed. (orig.)

  17. Graphite Isotope Ratio Method Development Report: Irradiation Test Demonstration of Uranium as a Low Fluence Indicator

    This report describes an irradiation test designed to investigate the suitability of uranium as a graphite isotope ratio method (GIRM) low fluence indicator. GIRM is a demonstrated concept that gives a graphite-moderated reactor's lifetime production based on measuring changes in the isotopic ratio of elements known to exist in trace quantities within reactor-grade graphite. Appendix I of this report provides a tutorial on the GIRM concept

  18. The First Limits on the Ultra-high Energy Neutrino Fluence from Gamma-ray Bursts

    Vieregg, A G; Allison, P; Baughman, B M; Beatty, J J; Belov, K; Besson, D Z; Bevan, S; Binns, W R; Chen, C; Chen, P; Clem, J M; Connolly, A; Detrixhe, M; De Marco, D; Dowkontt, P F; DuVernois, M; Gorham, P W; Grashorn, E W; Hill, B; Hoover, S; Huang, M; Israel, M H; Javaid, A; Liewer, K M; Matsuno, S; Mercurio, B C; Miki, C; Mottram, M; Nam, J; Nichol, R J; Romero-Wolf, A; Ruckman, L; Saltzberg, D; Seckel, D; Varner, G S; Wang, Y

    2011-01-01

    We set the first limits on the ultra-high energy (UHE) neutrino fluence at energies greater than 10^9 GeV from gamma-ray bursts (GRBs) based on data from the second flight of the ANtarctic Impulsive Transient Antenna (ANITA). During the 31 day flight of ANITA-II, 26 GRBs were recorded by Swift or Fermi. Of these, we analyzed the 12 GRBs which occurred during quiet periods when the payload was away from anthropogenic activity. In a blind analysis, we observe 0 events on a total background of 0.0044 events in the combined prompt window for all 12 low-background bursts. We also observe 0 events from the remaining 14 bursts. We place a 90% confidence level limit on the E^-4 prompt neutrino fluence of 2.5x10^17 GeV^3/cm^2 between 10^8 and 10^12 GeV from GRB090107A. This is the first reported limit on the UHE neutrino fluence from GRBs above 10^9 GeV, and the strongest limit above 10^8 GeV.

  19. Fluence-based dosimetry of proton and heavier ion beams using single track detectors.

    Klimpki, G; Mescher, H; Akselrod, M S; Jäkel, O; Greilich, S

    2016-02-01

    Due to their superior spatial resolution, small and biocompatible fluorescent nuclear track detectors (FNTDs) open up the possibility of characterizing swift heavy charged particle fields on a single track level. Permanently stored spectroscopic information such as energy deposition and particle field composition is of particular importance in heavy ion radiotherapy, since radiation quality is one of the decisive predictors for clinical outcome. Findings presented within this paper aim towards single track reconstruction and fluence-based dosimetry of proton and heavier ion fields. Three-dimensional information on individual ion trajectories through the detector volume is obtained using fully automated image processing software. Angular distributions of multidirectional fields can be measured accurately within  ±2° uncertainty. This translates into less than 5% overall fluence deviation from the chosen irradiation reference. The combination of single ion tracking with an improved energy loss calibration curve based on 90 FNTD irradiations with protons as well as helium, carbon and oxygen ions enables spectroscopic analysis of a detector irradiated in Bragg peak proximity of a 270 MeV u(-1) carbon ion field. Fluence-based dosimetry results agree with treatment planning software reference. PMID:26757791

  20. Cherenkov radiation fluence estimates in tissue for molecular imaging and therapy applications

    Glaser, Adam K.; Zhang, Rongxiao; Andreozzi, Jacqueline; Gladstone, David; Pogue, Brian

    2016-03-01

    Cherenkov radiation has emerged as a novel source of light with a number of applications in the biomedical sciences. It's unique properties, including its broadband emission spectrum, spectral weighting in the ultraviolet and blue wavebands, and local generation of light within a given tissue have made it an attractive source of light for techniques ranging from widefield imaging to oximetry and phototherapy. To help guide the future development of this field in the context of molecular imaging, quantitative estimates of the light fluence rates of Cherenkov radiation from a number of radionuclide and external radiotherapy beams in tissue was explored for the first time. Using Monte Carlo simulations, these values were found to be on the order of 0.1 - 1 nW/cm2 per MBq/g for radionuclides and 1 - 10 μW/cm2 per Gy/sec for external radiotherapy beams, dependent on the given waveband and optical properties. For phototherapy applications, the total light fluence was found to be on the order of nJ/cm2 for radionuclides, and mJ/cm2 for radiotherapy beams. To validate these findings, experimental validation was completed with an MV x-ray photon beam incident onto a tissue phantom, confirming the magnitudes of the simulation values. The results indicate that diagnostic potential is reasonable for Cherenkov excitation of molecular probes, but phototherapy may remain elusive at these relatively low fluence values.

  1. Effects of laser fluence on silicon modification by four-beam laser interference

    This paper discusses the effects of laser fluence on silicon modification by four-beam laser interference. In this work, four-beam laser interference was used to pattern single crystal silicon wafers for the fabrication of surface structures, and the number of laser pulses was applied to the process in air. By controlling the parameters of laser irradiation, different shapes of silicon structures were fabricated. The results were obtained with the single laser fluence of 354 mJ/cm2, 495 mJ/cm2, and 637 mJ/cm2, the pulse repetition rate of 10 Hz, the laser exposure pulses of 30, 100, and 300, the laser wavelength of 1064 nm, and the pulse duration of 7–9 ns. The effects of the heat transfer and the radiation of laser interference plasma on silicon wafer surfaces were investigated. The equations of heat flow and radiation effects of laser plasma of interfering patterns in a four-beam laser interference distribution were proposed to describe their impacts on silicon wafer surfaces. The experimental results have shown that the laser fluence has to be properly selected for the fabrication of well-defined surface structures in a four-beam laser interference process. Laser interference patterns can directly fabricate different shape structures for their corresponding applications

  2. Development of the processing software package for RPV neutron fluence determination methodology

    According to the INRNE methodology the neutron transport calculation is carried out by two steps. At the first step reactor core eigenvalue calculation is performed. This calculation is used for determination of the fixed source for the next step calculation of neutron transport from the reactor core to the RPV. Both calculation steps are performed by state of the art and tested codes. The interface software package DOSRC developed at INRNE is used as a link between these two calculations. The package transforms reactor core calculation results to neutron source input data in format appropriate for the neutron transport codes (DORT, TORT and ASYNT) based on the discrete ordinates method. These codes are applied for calculation of the RPV neutron flux and its responses - induced activity, radiation damage, neutron fluence etc. Fore more precise estimation of the neutron fluence, the INRNE methodology has been supplemented by the next improvements: - implementation of more advanced codes (PYTHIA/DERAB) for neutron-physics parameter calculations; - more detailed neutron source presentation; - verification of neutron fluence by statistically treated experimental data. (author)

  3. Very low-energy and low-fluence ion beam bombardment of naked plasmid DNA

    Ion beam bombardment of biological organisms has been recently applied to mutation breeding of both agricultural and horticultural plants. In order to explore relevant mechanisms, this study employed low-energy ion beams to bombard naked plasmid DNA. The study aimed at simulation of the final stage of the process of the ion beam bombardment of real cells to check whether and how very low-energy and low-fluence of ions can induce mutation. Argon and nitrogen ions at 5 keV and 2.5 keV respectively bombarded naked plasmid DNA pGFP to very low-fluences, an order of 1013 ions/cm2. Subsequently, DNA states were analyzed using electrophoresis. Results provided evidences that the very low-energy and low-fluence ion bombardment indeed altered the DNA structure from supercoil to short linear fragments through multiple double strand breaks and thus induced mutation, which was confirmed by transfer of the bombarded DNA into bacteria Escherichia coli and subsequent expression of the marker gene.

  4. Effect of cold work on void swelling in aluminium at high neutron fluences

    High purity aluminium (99.9995%) was deformed at room temperature to various degrees ranging up to 90%. The void population, produced by subsequent neutron irradiation of annealed and deformed specimens to fluences of 6.6 x 1024. 5.4 x 1025 and 2.2 x 1026 n m-2 (E>0.1 MeV) at 500C, was investigated by transmission electron microscopy. Between 5.4 x 1025 and 2.2 x 1026 n m-2 void swelling continues by increase of the void size, with the void density actually decreasing slightly. At the highest fluence level, which corresponds to 19 dpa, annealed material swells about 13% due to voids. At this fluence level, the average void size and volume fraction decrease marginally with increasing degree of cold work. Also, dislocation walls forming subgrains in the deformed specimens are still present. Voids are located within the subgrains, with void-free zones of variable thickness lining the subgrain walls and the grain boundaries. (orig.)

  5. Fluence-based dosimetry of proton and heavier ion beams using single track detectors

    Klimpki, G.; Mescher, H.; Akselrod, M. S.; Jäkel, O.; Greilich, S.

    2016-02-01

    Due to their superior spatial resolution, small and biocompatible fluorescent nuclear track detectors (FNTDs) open up the possibility of characterizing swift heavy charged particle fields on a single track level. Permanently stored spectroscopic information such as energy deposition and particle field composition is of particular importance in heavy ion radiotherapy, since radiation quality is one of the decisive predictors for clinical outcome. Findings presented within this paper aim towards single track reconstruction and fluence-based dosimetry of proton and heavier ion fields. Three-dimensional information on individual ion trajectories through the detector volume is obtained using fully automated image processing software. Angular distributions of multidirectional fields can be measured accurately within  ±2° uncertainty. This translates into less than 5% overall fluence deviation from the chosen irradiation reference. The combination of single ion tracking with an improved energy loss calibration curve based on 90 FNTD irradiations with protons as well as helium, carbon and oxygen ions enables spectroscopic analysis of a detector irradiated in Bragg peak proximity of a 270 MeV u-1 carbon ion field. Fluence-based dosimetry results agree with treatment planning software reference.

  6. Robust fluence map optimization via alternating direction method of multipliers with empirical parameter optimization.

    Gao, Hao

    2016-04-01

    For the treatment planning during intensity modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT), beam fluence maps can be first optimized via fluence map optimization (FMO) under the given dose prescriptions and constraints to conformally deliver the radiation dose to the targets while sparing the organs-at-risk, and then segmented into deliverable MLC apertures via leaf or arc sequencing algorithms. This work is to develop an efficient algorithm for FMO based on alternating direction method of multipliers (ADMM). Here we consider FMO with the least-square cost function and non-negative fluence constraints, and its solution algorithm is based on ADMM, which is efficient and simple-to-implement. In addition, an empirical method for optimizing the ADMM parameter is developed to improve the robustness of the ADMM algorithm. The ADMM based FMO solver was benchmarked with the quadratic programming method based on the interior-point (IP) method using the CORT dataset. The comparison results suggested the ADMM solver had a similar plan quality with slightly smaller total objective function value than IP. A simple-to-implement ADMM based FMO solver with empirical parameter optimization is proposed for IMRT or VMAT. PMID:26987680

  7. High fluence irradiation effect on the ion beam graft polymerization method

    Radiation graft polymerization method has been applied to make many industrial product. Ion beam graft polymerization method has been developed by Betz and many researchers, and we have also developed the method with proton whose energy is below a few MeV. Using the method, the substrate, e.g. polyethylene film, is graft-polymerized and has the graft chains near the surface. To conduct the method for some times, the structure of graft chains near the surface can be formed. When we want to produce the graft chains inside of the substrate, the graft chains near the surface are unnecessary. One of our objectives is to produce a functional polymer with a structure in the film. When the sample is irradiated in sufficiently high fluence, the sample can’t be graft-polymerized in the next irradiation. Comparing the density of radicals and the number of double bond with the degree of grafting, the reason why formation of a part not grafted in high fluence irradiation was discussed. Because the number of the double bond and the allyl radicals in PE are increased for high fluence irradiation, the number of the alkyl radical as a grafting point is decreased. Moreover, the alkyl radical is not produced in following irradiation since existence of double bond and peroxy radical

  8. Effects of laser fluence on silicon modification by four-beam laser interference

    Zhao, Le; Li, Dayou [JR3CN and CNM, Changchun University of Science and Technology, Changchun 130022 (China); JR3CN and IRAC, University of Bedfordshire, Luton LU1 3JU (United Kingdom); Wang, Zuobin, E-mail: wangz@cust.edu.cn; Yue, Yong [JR3CN and CNM, Changchun University of Science and Technology, Changchun 130022 (China); JR3CN and IRAC, University of Bedfordshire, Luton LU1 3JU (United Kingdom); DCSSE, Xi' an Jiaotong-Livepool University, Suzhou 215123 (China); Zhang, Jinjin; Yu, Miao; Li, Siwei [JR3CN and CNM, Changchun University of Science and Technology, Changchun 130022 (China)

    2015-12-21

    This paper discusses the effects of laser fluence on silicon modification by four-beam laser interference. In this work, four-beam laser interference was used to pattern single crystal silicon wafers for the fabrication of surface structures, and the number of laser pulses was applied to the process in air. By controlling the parameters of laser irradiation, different shapes of silicon structures were fabricated. The results were obtained with the single laser fluence of 354 mJ/cm{sup 2}, 495 mJ/cm{sup 2}, and 637 mJ/cm{sup 2}, the pulse repetition rate of 10 Hz, the laser exposure pulses of 30, 100, and 300, the laser wavelength of 1064 nm, and the pulse duration of 7–9 ns. The effects of the heat transfer and the radiation of laser interference plasma on silicon wafer surfaces were investigated. The equations of heat flow and radiation effects of laser plasma of interfering patterns in a four-beam laser interference distribution were proposed to describe their impacts on silicon wafer surfaces. The experimental results have shown that the laser fluence has to be properly selected for the fabrication of well-defined surface structures in a four-beam laser interference process. Laser interference patterns can directly fabricate different shape structures for their corresponding applications.

  9. Fluence-field modulated x-ray CT using multiple aperture devices

    Stayman, J. Webster; Mathews, Aswin; Zbijewski, Wojciech; Gang, Grace; Siewerdsen, Jeffrey; Kawamoto, Satomi; Blevis, Ira; Levinson, Reuven

    2016-03-01

    We introduce a novel strategy for fluence field modulation (FFM) in x-ray CT using multiple aperture devices (MADs). MAD filters permit FFM by blocking or transmitting the x-ray beam on a fine (0.1-1 mm) scale. The filters have a number of potential advantages over other beam modulation strategies including the potential for a highly compact design, modest actuation speed and acceleration requirements, and spectrally neutral filtration due to their essentially binary action. In this work, we present the underlying MAD filtration concept including a design process to achieve a specific class of FFM patterns. A set of MAD filters is fabricated using a tungsten laser sintering process and integrated into an x-ray CT test bench. A characterization of the MAD filters is conducted and compared to traditional attenuating bowtie filters and the ability to flatten the fluence profile for a 32 cm acrylic phantom is demonstrated. MAD-filtered tomographic data was acquired on the CT test bench and reconstructed without artifacts associated with the MAD filter. These initial studies suggest that MAD-based FFM is appropriate for integration in clinical CT system to create patient-specific fluence field profile and reduce radiation exposures.

  10. Robust fluence map optimization via alternating direction method of multipliers with empirical parameter optimization

    Gao, Hao

    2016-04-01

    For the treatment planning during intensity modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT), beam fluence maps can be first optimized via fluence map optimization (FMO) under the given dose prescriptions and constraints to conformally deliver the radiation dose to the targets while sparing the organs-at-risk, and then segmented into deliverable MLC apertures via leaf or arc sequencing algorithms. This work is to develop an efficient algorithm for FMO based on alternating direction method of multipliers (ADMM). Here we consider FMO with the least-square cost function and non-negative fluence constraints, and its solution algorithm is based on ADMM, which is efficient and simple-to-implement. In addition, an empirical method for optimizing the ADMM parameter is developed to improve the robustness of the ADMM algorithm. The ADMM based FMO solver was benchmarked with the quadratic programming method based on the interior-point (IP) method using the CORT dataset. The comparison results suggested the ADMM solver had a similar plan quality with slightly smaller total objective function value than IP. A simple-to-implement ADMM based FMO solver with empirical parameter optimization is proposed for IMRT or VMAT.

  11. Fluence-related risk coefficients using the Harderian gland data as an example

    Curtis, S. B.; Powers-Risius, P.; Alpen, E. L.; Townsend, L. W.; Wilson, J. W.; Fry, R. J. M.

    1992-01-01

    A new concept is introduced for assessing the risk of radiation-induced cancer to space travelers: a fluence-related risk coefficient F (called the risk cross section), which is the risk of a cancer per unit particle fluence for a given particle type. Fs are functions of the LET of the particles in the radiation field and, when integrated over fluence-LET spectra and summed, yield the risk of the endpoint of interest. As an example, tumor prevalence data in mice are used to estimate the probability of the induction of mouse Harderian-gland tumor per year on an extramagnetospheric mission inside an idealized shielding configuration of a spherical 1 g/sq cm hick aluminum shell. Results indicate a yearly tumor prevalence of 0.06 at solar minimum conditions, with 60 percent of this arising from charge components with Z between 10 and 28, and two-thirds of the contribution arising from LET components between 10 and 200 keV/micron.

  12. Use of glazes on porcelain from near ground zero to measure Hiroshima neutron fluence.

    MacDonald, J; Fleischer, R L; Fujita, S; Hoshi, M

    2003-10-01

    Several porcelain samples from almost directly beneath the atomic explosion at Hiroshima on 6 August 1945, have been scanned for induced fission tracks, produced mostly by the thermal neutrons from the bomb due to interactions with trace uranium in their glass coatings. The ability to use porcelain opens a new and abundant material for retrospective dosimetry. Four different samples had thermal neutron fluences in 1945 of 1.0, 3.8, 4.1, and 8.9 x 10(12) cm(-2). The different values are not caused by track fading, but are likely to result from differing shielding at different nearby positions. Assuming that the three highest fluences, which have overlapping uncertainties, are at locations of minimum shielding, the statistically weighted thermal fluence in the air at ground level and ground zero was 4.8 x 10(12) cm(-2) with a statistical uncertainty of 15%. This value lies between the calculated value of 6.5 x 10(12) given in DS86 and the 3.7 x 10(12) inferred from induced radionuclides by Hoshi et al. (1998). PMID:13678283

  13. Effects of laser fluence on the structural properties of pulsed laser deposited ruthenium thin films

    Lee, Wai-Keat; Wong, Hin-Yong; Chan, Kah-Yoong; Tou, Teck-Yong [Multimedia University, Centre for Advanced Devices and Systems (CADS), Faculty of Engineering, Cyberjaya, Selangor (Malaysia); Yong, Thian-Khok [Universiti Tunku Abdul Rahman, Faculty of Engineering and Science, Setapak, Kuala Lumpur (Malaysia); Yap, Seong-Shan [Norwegian University of Science and Technology, Institute of Physics, Trondheim (Norway)

    2010-08-15

    Ruthenium (Ru) has received great interest in recent years for applications in microelectronics. Pulsed laser deposition (PLD) enables the growth of Ru thin films at low temperatures. In this paper, we report for the first time the characterization of pulsed laser deposited Ru thin films. The deposition processes were carried out at room temperature in vacuum environment for different durations with a pulsed Nd:YAG laser of 355-nm laser wavelength, employing various laser fluences ranging from 2 J/cm{sup 2} to 8 J/cm{sup 2}. The effect of the laser fluence on the structural properties of the deposited Ru films was investigated using surface profilometry, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Ru droplets, some spherical in shape and some flattened into round discs were found on the deposited Ru. The droplets were correlated to ripple formations on the target during the laser-induced ejection from the target. In addition, crystalline Ru with orientations of (100), (101), and (002) was observed in the XRD spectra and their intensities were found to increase with increasing laser fluence and film thickness. Grain sizes ranging from 20 nm to 35 nm were deduced using the Scherrer formula. Optical emission spectroscopy (OES) and energy-dispersive X-ray spectroscopy (EDS) show that the composition of the plume and the deposited Ru film was of high purity. (orig.)

  14. Effects of laser fluence on the structural properties of pulsed laser deposited ruthenium thin films

    Ruthenium (Ru) has received great interest in recent years for applications in microelectronics. Pulsed laser deposition (PLD) enables the growth of Ru thin films at low temperatures. In this paper, we report for the first time the characterization of pulsed laser deposited Ru thin films. The deposition processes were carried out at room temperature in vacuum environment for different durations with a pulsed Nd:YAG laser of 355-nm laser wavelength, employing various laser fluences ranging from 2 J/cm2 to 8 J/cm2. The effect of the laser fluence on the structural properties of the deposited Ru films was investigated using surface profilometry, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Ru droplets, some spherical in shape and some flattened into round discs were found on the deposited Ru. The droplets were correlated to ripple formations on the target during the laser-induced ejection from the target. In addition, crystalline Ru with orientations of (100), (101), and (002) was observed in the XRD spectra and their intensities were found to increase with increasing laser fluence and film thickness. Grain sizes ranging from 20 nm to 35 nm were deduced using the Scherrer formula. Optical emission spectroscopy (OES) and energy-dispersive X-ray spectroscopy (EDS) show that the composition of the plume and the deposited Ru film was of high purity. (orig.)

  15. Natural neutron fluence rate and the equivalent dose in localities with different elevation and latitude

    The results of neutron field measurements in the ground-level atmosphere in localities with various elevations z (from 113 m to 2632 m) placed between geodetic latitudes 48o-52oN and longitudes 16o - 20o E are presented. A highly sensitive 3 He counter and a Bonner spectrometer were used in the measurements. The determined total neutron fluence rate Φt and the equivalent dose rate H induced by the natural neutron background in these localities change according to the exponential law ∼exp(αz), where α = (0.85 ± 0.05) x 10-3 m-1. Extrapolation of this dependence to sea level, gives Φt (0) = (100 ± 20) m-2.s-1 and H(0) (4.1 ± 1.2) nSv.h-1. The results of the measurements confirm a weak dependence of the total neutron fluence rate on the composition of dry ground. A considerable dependence of the natural neutron spectrum shape on the ground moisture content was observed. As measurements were made in the summer season during a long-lasting period without precipitation, the obtained value of H(z) could be considered as a maximum. The results are compared with calculated values using the Los Alamos Lahet Code System (LCS) both for the sea level and maximum elevation sites. The LCS was also used for calculation of the latitude variations in the total neutron fluence rates. (author)

  16. Recrystallization in polyvinylidene fluoride upon low fluence swift heavy ion impact

    Biswas, A.; Gupta, R.; Kumar, N.; Avasthi, D. K.; Singh, J. P.; Lotha, S.; Fink, D.; Paul, S. N.; Bose, S. K.

    2001-06-25

    Thin films (9 {mu}m) of polyvinylidene fluoride (PVDF) are irradiated by swift heavy ions (180 MeV Ag{sup 14+}) in the fluence range 1{times}10{sup 10}{endash}1{times}10{sup 12}ions/cm{sup 2} with an electronic linear energy transfer LET{similar_to}11 keV/nm. In sharp contrast to the previous results, the most characteristic crystalline asymmetric and symmetric {open_quotes}CH{sub 2}{close_quotes} doublets (located at 3025 and 2985 cm{sup {minus}1}), have shown remarkable increase in their respective Fourier transform infrared (FTIR) absorbance intensities upon low fluence ion impact (10{sup 10} ions/cm{sup 2}). This increase in absorbance is in consonance with the simultaneous decrease of the transmission intensities of other crystalline bending vibration bands located at 532 (CF{sub 2} bending), 614, 796, and 975 cm{sup {minus}1} (all due to CH{sub 2} bending) at the similar ion fluence. It appears most probable from the results that, being a polar polymer, the molecular dipoles in PVDF forming a hydrogen bond network get realigned upon irradiation into a highly ordered state of chain molecules in the crystalline regions and create volume elements as crystallites. {copyright} 2001 American Institute of Physics.

  17. Plastids and Carotenoid Accumulation.

    Li, Li; Yuan, Hui; Zeng, Yunliu; Xu, Qiang

    2016-01-01

    Plastids are ubiquitously present in plants and are the organelles for carotenoid biosynthesis and storage. Based on their morphology and function, plastids are classified into various types, i.e. proplastids, etioplasts, chloroplasts, amyloplasts, and chromoplasts. All plastids, except proplastids, can synthesize carotenoids. However, plastid types have a profound effect on carotenoid accumulation and stability. In this chapter, we discuss carotenoid biosynthesis and regulation in various plastids with a focus on carotenoids in chromoplasts. Plastid transition related to carotenoid biosynthesis and the different capacity of various plastids to sequester carotenoids and the associated effect on carotenoid stability are described in light of carotenoid accumulation in plants. PMID:27485226

  18. Radioecological monitoring of bryophytes

    Bryophytes are quite interesting partly because the mosses are characterized mostly by a higher degree of radionuclides accumulation than vascular plants. Therefore bryophytes can be considered as bio indicators. The data obtained evidence about different mechanism of accumulation of isotopes with bryophytes. Mosses may be used for organization of monitoring

  19. Texture analysis on the fluence map to evaluate the degree of modulation for volumetric modulated arc therapy

    Purpose: Texture analysis on fluence maps was performed to evaluate the degree of modulation for volumetric modulated arc therapy (VMAT) plans. Methods: A total of six textural features including angular second moment, inverse difference moment, contrast, variance, correlation, and entropy were calculated for fluence maps generated from 20 prostate and 20 head and neck VMAT plans. For each of the textural features, particular displacement distances (d) of 1, 5, and 10 were adopted. To investigate the deliverability of each VMAT plan, gamma passing rates of pretreatment quality assurance, and differences in modulating parameters such as multileaf collimator (MLC) positions, gantry angles, and monitor units at each control point between VMAT plans and dynamic log files registered by the Linac control system during delivery were acquired. Furthermore, differences between the original VMAT plan and the plan reconstructed from the dynamic log files were also investigated. To test the performance of the textural features as indicators for the modulation degree of VMAT plans, Spearman’s rank correlation coefficients (rs) with the plan deliverability were calculated. For comparison purposes, conventional modulation indices for VMAT including the modulation complexity score for VMAT, leaf travel modulation complexity score, and modulation index supporting station parameter optimized radiation therapy (MISPORT) were calculated, and their correlations were analyzed in the same way. Results: There was no particular textural feature which always showed superior correlations with every type of plan deliverability. Considering the results comprehensively, contrast (d = 1) and variance (d = 1) generally showed considerable correlations with every type of plan deliverability. These textural features always showed higher correlations to the plan deliverability than did the conventional modulation indices, except in the case of modulating parameter differences. The rs values of

  20. Texture analysis on the fluence map to evaluate the degree of modulation for volumetric modulated arc therapy

    Park, So-Yeon [Department of Radiation Oncology, Seoul National University Hospital, Seoul 110-744 (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 110-744 (Korea, Republic of); Biomedical Research Institute, Seoul National University College of Medicine, Seoul 110-744 (Korea, Republic of); Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul 110-799 (Korea, Republic of); Kim, Il Han [Department of Radiation Oncology, Seoul National University Hospital, Seoul 110-744 (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 110-744 (Korea, Republic of); Biomedical Research Institute, Seoul National University College of Medicine, Seoul 110-744 (Korea, Republic of); Department of Radiation Oncology, Seoul National University College of Medicine, Seoul 110-744 (Korea, Republic of); Ye, Sung-Joon [Department of Radiation Oncology, Seoul National University Hospital, Seoul 110-744, (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 110-744 (Korea, Republic of); Biomedical Research Institute, Seoul National University College of Medicine, Seoul 110-744 (Korea, Republic of); Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Seoul National University Graduate School of Convergence Science and Technology, Suwon 433-270 (Korea, Republic of); Carlson, Joel [Biomedical Research Institute, Seoul National University College of Medicine, Seoul 110-744 (Korea, Republic of); Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Seoul National University Graduate School of Convergence Science and Technology, Suwon 433-270 (Korea, Republic of); and others

    2014-11-01

    Purpose: Texture analysis on fluence maps was performed to evaluate the degree of modulation for volumetric modulated arc therapy (VMAT) plans. Methods: A total of six textural features including angular second moment, inverse difference moment, contrast, variance, correlation, and entropy were calculated for fluence maps generated from 20 prostate and 20 head and neck VMAT plans. For each of the textural features, particular displacement distances (d) of 1, 5, and 10 were adopted. To investigate the deliverability of each VMAT plan, gamma passing rates of pretreatment quality assurance, and differences in modulating parameters such as multileaf collimator (MLC) positions, gantry angles, and monitor units at each control point between VMAT plans and dynamic log files registered by the Linac control system during delivery were acquired. Furthermore, differences between the original VMAT plan and the plan reconstructed from the dynamic log files were also investigated. To test the performance of the textural features as indicators for the modulation degree of VMAT plans, Spearman’s rank correlation coefficients (r{sub s}) with the plan deliverability were calculated. For comparison purposes, conventional modulation indices for VMAT including the modulation complexity score for VMAT, leaf travel modulation complexity score, and modulation index supporting station parameter optimized radiation therapy (MI{sub SPORT}) were calculated, and their correlations were analyzed in the same way. Results: There was no particular textural feature which always showed superior correlations with every type of plan deliverability. Considering the results comprehensively, contrast (d = 1) and variance (d = 1) generally showed considerable correlations with every type of plan deliverability. These textural features always showed higher correlations to the plan deliverability than did the conventional modulation indices, except in the case of modulating parameter differences. The r

  1. Recent findings on blistering and deuterium retention in tungsten exposed to high-fluence deuterium plasma

    Full text of publication follows: Blistering occurs at tungsten exposed to high-fluence deuterium plasma, even if the ion energy is too low to create displacement damage [1, 2]. In this study, blistering and deuterium retention in various tungsten exposed to high-fluence (up to 1027 D/m2 ) of high flux (1022 D+/m2/s) and low-energy (38 eV) deuterium plasma were examined in the temperature range of 315 K to 1000 K with scanning electron microscopy (SEM), focused ion beam (FIB), thermal desorption spectroscopy (TDS) and positron annihilation (PA). At the exposure temperature of 315 K, only low-dome blisters with sizes of less than a few microns appeared even if the fluence reached 1027 D/m2. At around 400 K, the blisters became much denser and the dome of blisters became a little higher. Peculiar change occurred around 500 K, where two kinds of blisters appeared. One is the large blisters with sizes of a few tens of microns and varying ratios of height against chord (up to 0.6), and the other is the high-dome small blisters with chords of less than a few microns and large ratio of height against chord (about 0.7). Blisters became much sparser as the temperature increased to above 600 K and disappeared at 1000 K. In addition, the phenomenon of blister bursting with a tail, or partially-opened or fully-opened lid was found after plasma exposure or TDS experiments . During TDS experiments, bursting release with numerous sadden peaks was newly observed by setting the time resolution of quadrupole mass spectrometer to about 0.3 s. Deuterium retention showed the maximum around 500 K, corresponding to the appearance of two kinds of high-dome blisters. furthermore, the amount of deuterium retained in tungsten increased with the increasing fluence, roughly following the proportional relationship with the root of the exposure time. Besides the strong dependence upon the exposure temperature, blistering and deuterium retention also showed significant dependence upon the

  2. Experimental realization of fluence field modulated CT using digital beam attenuation

    Tailoring CT scan acquisition parameters to individual patients is a topic of much research in the CT imaging community. It is now common place to find automatically adjusted tube current options for modern CT scanners. In addition, the use of beam shaping filters, commonly called bowtie filters, is available on most CT systems and allows for different body regions to receive different incident x-ray fluence distributions. However, no method currently exists which allows for the form of the incident x-ray fluence distribution to change as a function of the view angle. This study represents the first experimental realization of fluence field modulated CT (FFMCT) for a c-arm geometry CT scan. X-ray fluence modulation is accomplished using a digital beam attenuator (DBA). The device is composed of ten iron wedge pairs that modulate the thickness of iron, the x-rays must traverse before reaching a patient. Using this device, experimental data was taken using a Siemens Zeego c-arm scanner. Scans were performed on a cylindrical polyethylene phantom and on two different sections of an anthropomorphic phantom. The DBA was used to equalize the x-ray fluence striking the detector for each scan. Non DBA, or ‘flat field’ scans were also acquired of the same phantom objects for comparison. In addition, a scan was performed in which the DBA was used to enable volume of interest (VOI) imaging. In VOI, only a small sub-volume within a patient receives full dose and the rest of the patient receives a much lower dose. Data corrections unique to using a piece-wise constant modulator were also developed. The feasibility of FFMCT implemented using a DBA device has been demonstrated. Initial results suggest dose reductions of up to 3.6 times relative to ‘flat field’ CT. In addition to dose reduction, the DBA enables a large improvement in image noise uniformity and the ability to provide regionally enhanced signal to noise using VOI imaging techniques. The results presented in

  3. Analysis of the longitudinal dependence of the downstream fluence of large solar energetic proton events

    Pacheco, Daniel; Sanahuja, Blai; Aran, Angels; Agueda, Neus; Jiggens, Piers

    2016-07-01

    Simulations of the solar energetic particle (SEP) intensity-time profiles are needed to estimate the radiation environment for interplanetary missions. At present, the physics-based models applied for such a purpose, and including a moving source of particles, are not able to model the portion of the SEP intensity enhancement occurring after the coronal/interplanetary shock crossing by the observer (a.k.a. the downstream region). This is the case, for example, of the shock-and-particle model used to build the SOLPENCO2 code. SOLPENCO2 provides the statistical modelling tool developed in the ESA/SEPEM project for interplanetary missions with synthetic SEP event simulations for virtual spacecraft located at heliocentric distances between 0.2 AU and 1.6 AU (http://dev.sepem.oma.be/). In this work we present an analysis of 168 individual SEP events observed at 1 AU from 1988 to 2013. We identify the solar eruptive phenomena associated with these SEP events, as well as the in-situ passage of interplanetary shocks. For each event, we quantify the amount of fluence accounted in the downstream region, i.e. after the passage of the shock, at the 11 SEPEM reference energy channels (i.e., from 5 to 300 MeV protons). First, from the subset of SEP events simultaneously detected by near Earth spacecraft (using SEPEM reference data) and by one of the STEREO spacecraft, we select those events for which the downstream region can be clearly determined. From the 8 selected multi-spacecraft events, we find that the western observations of each event have a minor downstream contribution than their eastern counterpart, and that the downstream-to-total fluence ratio of these events decreases as a function of the energy. Hence, there is a variation of the downstream fluence with the heliolongitude in SEP events. Based on this result, we study the variation of the downstream-to-total fluence ratios of the total set of individual events. We confirm the eastern-to-western decrease of the

  4. Chimpanzee accumulative stone throwing.

    Kühl, Hjalmar S; Kalan, Ammie K; Arandjelovic, Mimi; Aubert, Floris; D'Auvergne, Lucy; Goedmakers, Annemarie; Jones, Sorrel; Kehoe, Laura; Regnaut, Sebastien; Tickle, Alexander; Ton, Els; van Schijndel, Joost; Abwe, Ekwoge E; Angedakin, Samuel; Agbor, Anthony; Ayimisin, Emmanuel Ayuk; Bailey, Emma; Bessone, Mattia; Bonnet, Matthieu; Brazolla, Gregory; Buh, Valentine Ebua; Chancellor, Rebecca; Cipoletta, Chloe; Cohen, Heather; Corogenes, Katherine; Coupland, Charlotte; Curran, Bryan; Deschner, Tobias; Dierks, Karsten; Dieguez, Paula; Dilambaka, Emmanuel; Diotoh, Orume; Dowd, Dervla; Dunn, Andrew; Eshuis, Henk; Fernandez, Rumen; Ginath, Yisa; Hart, John; Hedwig, Daniela; Ter Heegde, Martijn; Hicks, Thurston Cleveland; Imong, Inaoyom; Jeffery, Kathryn J; Junker, Jessica; Kadam, Parag; Kambi, Mohamed; Kienast, Ivonne; Kujirakwinja, Deo; Langergraber, Kevin; Lapeyre, Vincent; Lapuente, Juan; Lee, Kevin; Leinert, Vera; Meier, Amelia; Maretti, Giovanna; Marrocoli, Sergio; Mbi, Tanyi Julius; Mihindou, Vianet; Moebius, Yasmin; Morgan, David; Morgan, Bethan; Mulindahabi, Felix; Murai, Mizuki; Niyigabae, Protais; Normand, Emma; Ntare, Nicolas; Ormsby, Lucy Jayne; Piel, Alex; Pruetz, Jill; Rundus, Aaron; Sanz, Crickette; Sommer, Volker; Stewart, Fiona; Tagg, Nikki; Vanleeuwe, Hilde; Vergnes, Virginie; Willie, Jacob; Wittig, Roman M; Zuberbuehler, Klaus; Boesch, Christophe

    2016-01-01

    The study of the archaeological remains of fossil hominins must rely on reconstructions to elucidate the behaviour that may have resulted in particular stone tools and their accumulation. Comparatively, stone tool use among living primates has illuminated behaviours that are also amenable to archaeological examination, permitting direct observations of the behaviour leading to artefacts and their assemblages to be incorporated. Here, we describe newly discovered stone tool-use behaviour and stone accumulation sites in wild chimpanzees reminiscent of human cairns. In addition to data from 17 mid- to long-term chimpanzee research sites, we sampled a further 34 Pan troglodytes communities. We found four populations in West Africa where chimpanzees habitually bang and throw rocks against trees, or toss them into tree cavities, resulting in conspicuous stone accumulations at these sites. This represents the first record of repeated observations of individual chimpanzees exhibiting stone tool use for a purpose other than extractive foraging at what appear to be targeted trees. The ritualized behavioural display and collection of artefacts at particular locations observed in chimpanzee accumulative stone throwing may have implications for the inferences that can be drawn from archaeological stone assemblages and the origins of ritual sites. PMID:26923684

  5. Geochemistry Model Validation Report: External Accumulation Model

    The purpose of this Analysis and Modeling Report (AMR) is to validate the External Accumulation Model that predicts accumulation of fissile materials in fractures and lithophysae in the rock beneath a degrading waste package (WP) in the potential monitored geologic repository at Yucca Mountain. (Lithophysae are voids in the rock having concentric shells of finely crystalline alkali feldspar, quartz, and other materials that were formed due to entrapped gas that later escaped, DOE 1998, p. A-25.) The intended use of this model is to estimate the quantities of external accumulation of fissile material for use in external criticality risk assessments for different types of degrading WPs: U.S. Department of Energy (DOE) Spent Nuclear Fuel (SNF) codisposed with High Level Waste (HLW) glass, commercial SNF, and Immobilized Plutonium Ceramic (Pu-ceramic) codisposed with HLW glass. The scope of the model validation is to (1) describe the model and the parameters used to develop the model, (2) provide rationale for selection of the parameters by comparisons with measured values, and (3) demonstrate that the parameters chosen are the most conservative selection for external criticality risk calculations. To demonstrate the applicability of the model, a Pu-ceramic WP is used as an example. The model begins with a source term from separately documented EQ6 calculations; where the source term is defined as the composition versus time of the water flowing out of a breached waste package (WP). Next, PHREEQC, is used to simulate the transport and interaction of the source term with the resident water and fractured tuff below the repository. In these simulations the primary mechanism for accumulation is mixing of the high pH, actinide-laden source term with resident water; thus lowering the pH values sufficiently for fissile minerals to become insoluble and precipitate. In the final section of the model, the outputs from PHREEQC, are processed to produce mass of accumulation

  6. New approach for absolute fluence distribution calculations in Monte Carlo simulations of light propagation in turbid media

    A novel way to attain three dimensional fluence rate maps from Monte-Carlo simulations of photon propagation is presented in this work. The propagation of light in a turbid medium is described by the radiative transfer equation and formulated in terms of radiance. For many applications, particularly in biomedical optics, the fluence rate is a more useful quantity and directly derived from the radiance by integrating over all directions. Contrary to the usual way which calculates the fluence rate from absorbed photon power, the fluence rate in this work is directly calculated from the photon packet trajectory. The voxel based algorithm works in arbitrary geometries and material distributions. It is shown that the new algorithm is more efficient and also works in materials with a low or even zero absorption coefficient. The capabilities of the new algorithm are demonstrated on a curved layered structure, where a non-scattering, non-absorbing layer is sandwiched between two highly scattering layers

  7. Epoxy-paint stripping using TEA CO2 laser: Determination of threshold fluence and the process parameters

    Kumar, Manoj; Bhargava, P.; Biswas, A. K.; Sahu, Shasikiran; Mandloi, V.; Ittoop, M. O.; Khattak, B. Q.; Tiwari, M. K.; Kukreja, L. M.

    2013-03-01

    It is shown that the threshold fluence for laser paint stripping can be accurately estimated from the heat of gasification and the absorption coefficient of the epoxy-paint. The threshold fluence determined experimentally by stripping of the epoxy-paint on a substrate using a TEA CO2 laser matches closely with the calculated value. The calculated threshold fluence and the measured absorption coefficient of the paint allowed us to determine the epoxy paint thickness that would be removed per pulse at a given laser fluence even without experimental trials. This was used to predict the optimum scan speed required to strip the epoxy-paint of a given thickness using a high average power TEA CO2 laser. Energy Dispersive X-Ray Fluorescence (EDXRF) studies were also carried out on laser paint-stripped concrete substrate to show high efficacy of this modality.

  8. Intense Pulsed Light and Low-Fluence Q-Switched Nd:YAG Laser Treatment in Melasma Patients

    Na, Se Young; Cho, Soyun; Lee, Jong Hee

    2012-01-01

    Background Recently, low fluence collimated Q-switched (QS) Nd:YAG laser has drawn attention for the treatment of melasma. However, it needs a lot of treatment sessions for the substantial results and repetitive laser exposures may end up with unwanted depigmentation. Objective We evaluated the clinical effects and safety of the combinational treatment, using intense pulsed light (IPL) and low fluence QS Nd:YAG laser. Methods Retrospective case series of 20 female patients, with mixed type me...

  9. Antiproton Accumulator (AA)

    Photographic Service

    1980-01-01

    The AA in its final stage of construction, before it disappeared from view under concrete shielding. Antiprotons were first injected, stochastically cooled and accumulated in July 1980. From 1981 on, the AA provided antiprotons for collisions with protons, first in the ISR, then in the SPS Collider. From 1983 on, it also sent antiprotons, via the PS, to the Low-Energy Antiproton Ring (LEAR). The AA was dismantled in 1997 and shipped to Japan.

  10. Accumulation of satellites

    Formation and evolution of circumplanetary satellite swarms are investigated. Characteristic times of various processes are estimated. The characteristic time for the accumulation of the bodies in the swarm was several orders of magnitude shorter than that of the planet, i.e. than the time of the replenishment of the material by the swarm (108 yr). The model of the accumulation of the swarm is constructed taking into account the increase of its mass due to trapping of heliocentrically moving particles and its decrease due to outfall of the inner part of the swarm onto the growing planet. The accumulation of circumplanetary bodies is also considered. The main features of the evolution of the swarm essentially depend on the size distribution of bodies in the swarm and in the zone of the planet and also on the degree of the concentration of the swarm mass toward the planet. If the sum of the exponents of the inverse power laws of these distributions is less than 7, the model of the transparent swarm developed in this paper should be preferred. When this sum is greater than 7, the model of opaque swarm suggested by A. Harris and W.M. Kaula is better. There is predominant trapping of small particles into the swarm due to their more frequent collisions. Optical thickness of the protoplanetary cloud in radial direction is estimated. It is shown that at the final stage of the planetary accumulation, the cloud was semitransparent in the region of terrestrial planets and volatile substances evaporated at collisions could be swept out from the outer parts of the satellite swarm by the solar wind

  11. Information Accumulation in Development

    Acemoglu, Daron; Zilibotti, Fabrizio

    1998-01-01

    We propose a model in which economic relations and institutions in advanced and less developed countires differ as these societies have access to different amounts of information. The lack of information in less developped economies makes it hard to evaluate the performance of managers, and leads to high "agency costs". Differencies in the amount of information have a variety of sources. As well as factors related to the informational infrastructure, we emphasize that societies accumulate inf...

  12. Chimpanzee accumulative stone throwing

    Hjalmar S Kühl; Kalan, Ammie K.; Mimi Arandjelovic; Floris Aubert; Lucy D’Auvergne; Annemarie Goedmakers; Sorrel Jones; Laura Kehoe; Sebastien Regnaut; Alexander Tickle; Els Ton; Joost van Schijndel; Abwe, Ekwoge E; Samuel Angedakin; Anthony Agbor

    2016-01-01

    The authors would like to thank the Max Planck Society and Krekeler Foundation for generous funding of the Pan African Programme. The study of the archaeological remains of fossil hominins must rely on reconstructions to elucidate the behaviour that may have resulted in particular stone tools and their accumulation. Comparatively, stone tool use among living primates has illuminated behaviours that are also amenable to archaeological examination, permitting direct observations of the behav...

  13. Physics of the Isotopic Dependence of Galactic Cosmic Ray Fluence Behind Shielding

    Cucinotta, Francis A.; Saganti, Premkumar B.; Hu, Xiao-Dong; Kim, Myung-Hee Y.; Cleghorn, Timothy F.; Wilson, John W.; Tripathi, Ram K.; Zeitlin, Cary J.

    2003-01-01

    For over 25 years, NASA has supported the development of space radiation transport models for shielding applications. The NASA space radiation transport model now predicts dose and dose equivalent in Earth and Mars orbit to an accuracy of plus or minus 20%. However, because larger errors may occur in particle fluence predictions, there is interest in further assessments and improvements in NASA's space radiation transport model. In this paper, we consider the effects of the isotopic composition of the primary galactic cosmic rays (GCR) and the isotopic dependence of nuclear fragmentation cross-sections on the solution to transport models used for shielding studies. Satellite measurements are used to describe the isotopic composition of the GCR. Using NASA's quantum multiple-scattering theory of nuclear fragmentation (QMSFRG) and high-charge and energy (HZETRN) transport code, we study the effect of the isotopic dependence of the primary GCR composition and secondary nuclei on shielding calculations. The QMSFRG is shown to accurately describe the iso-spin dependence of nuclear fragmentation. The principal finding of this study is that large errors (plus or minus 100%) will occur in the mass-fluence spectra when comparing transport models that use a complete isotope grid (approximately 170 ions) to ones that use a reduced isotope grid, for example the 59 ion-grid used in the HZETRN code in the past, however less significant errors (less than 20%) occur in the elemental-fluence spectra. Because a complete isotope grid is readily handled on small computer workstations and is needed for several applications studying GCR propagation and scattering, it is recommended that they be used for future GCR studies.

  14. In situ auger analysis of surface composition during high fluence ion implantation

    Baldwin, D. A.; Sartwell, B. D.; Singer, I. L.

    1985-03-01

    A multi-technique ultrahigh vacuum (UHV) target chamber has been used to perform in situ Auger electron spectroscopic (AES) analysis during ion implantation and AES sputter depth profiling of the substrate within 1-2 min after implantation. Iron was implanted with 150 keV Ti + at a 45° angle of incidence in a target chamber with pressures ranging from 8 × 10 -9 Torr of residual gases up to 1 × 10 -5 Torr of intentionally admitted CO gas. A fluence of ∼1.0 × 10 16cm -2 was needed to sputter away the C-covered air-formed oxide. The implanted Ti reached the surface at the 1 at.% level by ∼1.5 × 10 16cm -2. With increasing fluence, the Ti surface concentration increased to ∼15 at.% at steady-state with a curve shape that was concave downward at all fluences. The surface C concentration was found to be proportional to that of Ti for implants in CO, supporting a vacuum carburization model. Substantial O surface concentration (15-20 at.%) was detected for these runs but depth profiles showed only carburization, not oxidation, of the implanted layer. Even in the best vacuum available (8 × 10 -9Torr), some carburization was observed and was attributed to residual gas absorption. An increase in Ti retained dose with increasing CO pressure has been observed but not yet independently confirmed. The Ti/Fe surface concentration ratio is higher for implants done in CO, and this is discussed in terms of modification of the sputter yield for Ti.

  15. Cherenkov radiation fluence estimates in tissue for molecular imaging and therapy applications.

    Glaser, Adam K; Zhang, Rongxiao; Andreozzi, Jacqueline M; Gladstone, David J; Pogue, Brian W

    2015-09-01

    Cherenkov radiation has recently emerged as an interesting phenomenon for a number of applications in the biomedical sciences. Its unique properties, including broadband emission spectrum, spectral weight in the ultraviolet and blue wavebands, and local generation of light within a given tissue, have made it an attractive new source of light within tissue for molecular imaging and phototherapy applications. While several studies have investigated the total Cherenkov light yield from radionuclides in units of [photons/decay], further consideration of the light propagation in tissue is necessary to fully consider the utility of this signal in vivo. Therefore, to help further guide the development of this novel field, quantitative estimates of the light fluence rate of Cherenkov radiation from both radionuclides and radiotherapy beams in a biological tissue are presented for the first time. Using Monte Carlo simulations, these values were found to be on the order of 0.01-1 nW cm(-2) per MBq g(-1) for radionuclides, and 1-100 μW cm(-2) per Gy s(-1) for external radiotherapy beams, dependent on the given waveband, optical properties, and radiation source. For phototherapy applications, the total light fluence was found to be on the order of nJ cm(-2) for radionuclides, and mJ cm(-2) for radiotherapy beams. The results indicate that diagnostic potential is reasonable for Cherenkov excitation of molecular probes, but phototherapy may remain elusive at such exceedingly low fluence values. The results of this study are publicly available for distribution online at www.dartmouth.edu/optmed/. PMID:26270125

  16. Variability in fluence and spectrum of high-energy photon bursts produced by lightning leaders

    Celestin, Sebastien; Xu, Wei; Pasko, Victor P.

    2015-12-01

    In this paper, we model the production and acceleration of thermal runaway electrons during negative corona flash stages of stepping lightning leaders and the corresponding terrestrial gamma ray flashes (TGFs) or negative cloud-to-ground (-CG) lightning-produced X-ray bursts in a unified fashion. We show how the source photon spectrum and fluence depend on the potential drop formed in the lightning leader tip region during corona flash and how the X-ray burst spectrum progressively converges toward typical TGF spectrum as the potential drop increases. Additionally, we show that the number of streamers produced in a negative corona flash, the source electron energy distribution function, the corresponding number of photons, and the photon energy distribution and transport through the atmosphere up to low-orbit satellite altitudes exhibit a very strong dependence on this potential drop. This leads to a threshold effect causing X-rays produced by leaders with potentials lower than those producing typical TGFs extremely unlikely to be detected by low-orbit satellites. Moreover, from the number of photons in X-ray bursts produced by -CGs estimated from ground observations, we show that the proportionality between the number of thermal runaway electrons and the square of the potential drop in the leader tip region during negative corona flash proposed earlier leads to typical photon fluences on the order of 1 ph/cm2 at an altitude of 500 km and a radial distance of 200 km for intracloud lightning discharges producing 300 MV potential drops, which is consistent with observations of TGF fluences and spectra from satellites.

  17. Cherenkov radiation fluence estimates in tissue for molecular imaging and therapy applications

    Cherenkov radiation has recently emerged as an interesting phenomenon for a number of applications in the biomedical sciences. Its unique properties, including broadband emission spectrum, spectral weight in the ultraviolet and blue wavebands, and local generation of light within a given tissue, have made it an attractive new source of light within tissue for molecular imaging and phototherapy applications. While several studies have investigated the total Cherenkov light yield from radionuclides in units of [photons/decay], further consideration of the light propagation in tissue is necessary to fully consider the utility of this signal in vivo. Therefore, to help further guide the development of this novel field, quantitative estimates of the light fluence rate of Cherenkov radiation from both radionuclides and radiotherapy beams in a biological tissue are presented for the first time. Using Monte Carlo simulations, these values were found to be on the order of 0.01–1 nW cm−2 per MBq g−1 for radionuclides, and 1–100 μW cm−2 per Gy s−1 for external radiotherapy beams, dependent on the given waveband, optical properties, and radiation source. For phototherapy applications, the total light fluence was found to be on the order of nJ cm−2 for radionuclides, and mJ cm−2 for radiotherapy beams. The results indicate that diagnostic potential is reasonable for Cherenkov excitation of molecular probes, but phototherapy may remain elusive at such exceedingly low fluence values. The results of this study are publicly available for distribution online at www.dartmouth.edu/optmed/. (paper)

  18. Efficient localized heating of silver nanoparticles by low-fluence femtosecond laser pulses

    Huang, H.; Sivayoganathan, M. [Centre for Advanced Materials Joining, University of Waterloo, Ontario, N2L 3G1 (Canada); Department of Mechanical & Mechatronics Engineering, University of Waterloo, Ontario, N2L 3G1 (Canada); Duley, W.W. [Centre for Advanced Materials Joining, University of Waterloo, Ontario, N2L 3G1 (Canada); Department of Physics & Astronomy, University of Waterloo, Ontario, N2L 3G1 (Canada); Zhou, Y., E-mail: nzhou@uwaterloo.ca [Centre for Advanced Materials Joining, University of Waterloo, Ontario, N2L 3G1 (Canada); Department of Mechanical & Mechatronics Engineering, University of Waterloo, Ontario, N2L 3G1 (Canada)

    2015-03-15

    Highlights: • Obtained efficient localized heating (melting) of silver nanoparticles plasmonic structure, which is induced by the excitation of surface plasmon under femtosecond laser irradiation. • Resonance condition is not required here for surface plasmon induced efficient heating; this is different from previous studies where surface plasmon resonance is usually used to obtain enough heating generation. Compared to the previous studies of off-resonance laser heating, the laser fluence used in this study to obtain melting of silver nanoparticles is much lower, only 7.2 mJ/cm{sup 2}. • Beside surface plasmon itself induced heating, surface plasmon induced polymer shell deformation which resulted in electron and ion emission was identified to have certain contribution to the heating of silver nanoparticles plasmonic structure. - Abstract: Highly localized heating can be obtained in plasmonic nanomaterials using laser excitation but the high fluences required often produce unacceptable damage in and near irradiated components and structures. In this work we show that plasmonic nanostructures involving aggregated Ag nanoparticles (Ag NPs) can be heated effectively without attendant damage to the surrounding material when these structures are irradiated with many overlapping femtosecond (fs) laser pulses at very low fluence. Under these conditions, the effectiveness of heating is such that the temperature of 50 nm Ag NPs can be raised to their melting point from room temperature. Aggregates of these NPs are then observed to grow into larger spherical particles as laser heating continues. Imaging of these materials shows that the initiation of melting in individual Ag NPs depends on the local geometry surrounding each NP and on the polarization of the incident laser radiation. Finite difference time domain (FDTD) simulations indicate that melting is triggered by localized surface plasmon (LSP)-induced electric field enhancement at “hotspots”.

  19. The FLUKA study of the secondary particles fluence in the AD-Antiproton Decelerator target area

    Calviani, M

    2014-01-01

    In this paper we present Monte Carlo FLUKA simulations [1, 2] carried out to investigate the secondary particles fluence emerging from the antiproton production target and their spatial distribution in the AD target area. The detailed quantitative analysis has been performed for different positions along the magnet dog-leg as well as after the main collimator. These results allow tuning the position of the new beam current transformers (BCT) in the target area, in order to have a precise pulse-by-pulse evaluation of the intensity of negative particles injected in the AD-ring before the deceleration phase.

  20. Direct UV written planar Bragg gratings that feature zero fluence induced birefringence

    Holmes, Christopher; Cooper, Peter A.; Fernando, Harendra N. J.; Stroll, Andreas; Gates, James C.; Krishnan, Chirenjeevi; Haynes, Roger; Mennea, Paolo L.; Carpenter, Lewis G.; Gawith, Corin B. E.; Roth, Martin M.; Charlton, Martin D.; Smith, Peter G. R.

    2015-12-01

    Direct UV writing is a planar fabrication process capable of simultaneously defining waveguides and Bragg gratings. The technique is fully computer controlled and uniquely uses a small focused spot ~7 μm in diameter for direct writing exposure. This work investigates its use to achieve phase trimming and Bragg grating definition in silica-on-silicon lithographic waveguides. It is observed that birefringence control using direct UV writing can be made independent of exposure fluence with this technique through tailoring substrate stress. The result is demonstrated experimentally and supported theoretically using finite element analysis.

  1. Measurements on HV-CMOS active sensors after irradiation to HL-LHC fluences

    Ristic, B.

    2015-04-01

    During the long shutdown (LS) 3 beginning 2022 the LHC will be upgraded for higher luminosities pushing the limits especially for the inner tracking detectors of the LHC experiments. In order to cope with the increased particle rate and radiation levels the ATLAS Inner Detector will be completely replaced by a purely silicon based one. Novel sensors based on HV-CMOS processes prove to be good candidates in terms of spatial resolution and radiation hardness. In this paper measurements conducted on prototypes built in the AMS H18 HV-CMOS process and irradiated to fluences of up to 2·1016 neq cm-2 are presented.

  2. Fast neutron fluence evaluation of the smart reactor pressure vessel by using the GEOSHIELD code

    In Korea, the design of an advanced integral reactor system called SMART has been developed by KAERI to supply energy for seawater desalination as well as an electricity generation. A fast neutron fluence distribution at the SMART reactor pressure vessel was evaluated to confirm the integrity of the vessel by using the GEOSHIELD code. The GEOSHIELD code was developed by KAERI in order to prepare an input list including a geometry modeling of the DORT code and to process results from the DORT code output list. Results by a GEOSHIELD code processing and by a manual processing of the DORT show a good agreement. (author)

  3. Exploratory study of burn time, duty factor, and fluence on ITER activation hazards

    The safety analyses for the Conceptual Design Activity (CDA) of the International Thermonuclear Experimental Reactor (ITER) were based on the simplifying assumption that the activation of materials occurs continuously. Since the analyses showed a significant hazard, it is appropriate to examine how much hazard reduction might occur if this conservative assumption were relaxed. This report explores how much reduction might be gained by considering non-continuous operation, that is, by considering plasma burn time, duty factor, and integrated fluence. Other factors impacting activation hazards - material choice, flux, and size - are not considered here

  4. The First Limits on the Ultra-high Energy Neutrino Fluence from Gamma-ray Bursts

    Vieregg, A. G.; Palladino, K.; Allison, P.; Baughman, B. M.; Beatty, J. J.; Belov, K.; Besson, D. Z.; Bevan, S; Binns, W. R.; Chen, C.; Chen, P; Clem, J. M.; Connolly, A.; Detrixhe, M.; De Marco, D.

    2011-01-01

    We set the first limits on the ultra-high energy (UHE) neutrino fluence at energies greater than 10^9 GeV from gamma-ray bursts (GRBs) based on data from the second flight of the ANtarctic Impulsive Transient Antenna (ANITA). During the 31 day flight of ANITA-II, 26 GRBs were recorded by Swift or Fermi. Of these, we analyzed the 12 GRBs which occurred during quiet periods when the payload was away from anthropogenic activity. In a blind analysis, we observe 0 events on a total background of 0...

  5. Residual radioactivity measurement in Hiroshima and Nagasaki for the evaluation of DS86 neutron fluence

    Residual 152Eu activity produced by neutrons from the Nagasaki atomic bomb has been measured in seven mineral samples located up to 1142 m from the epicenter. Europium was chemically separated from the sample and gamma-ray measurement was carried out with a well-type Ge detector. Deduced specific activities were compared with previous measurements and with activation calculation based on the DS86 neutron fluence. Present results are slightly higher than the calculation at far distances. However, systematic discrepancy as has been observed in Hiroshima is not clear. Further measurements for samples beyond 1000 m from the hypocenter are necessary to ensure the discrepancy problem. (author)

  6. Neutron Fluences and Radiation Damage Parameters for the HFIR-MFE-RB-17J Experiment

    The HFIR-MFE-RB-17J experiment was conducted in the removable beryllium (RB) position of HFIR with a Eu2O2 shield. The irradiation was conducted from April 27, 2004, to May 18, 2005. The total exposure was for 353.6 FPD (full power days). Reactor dosimetry capsules were analyzed and the activation data were used to provide the best estimates of the neutron fluences and radiation damage parameters as a function of height relative to midplane of the reactor.

  7. Neutron Fluences and Radiation Damage Parameters for the HFIR-MFE-RB-14J Experiment

    The HFIR-MFE-RB-14J experiment was conducted in the unshielded removable beryllium (RB) position of HFIR. The irradiation of the assembly occurred for two separated time periods. The first irradiation was from June 3, 1999 to August 27, 1999. The second irradiation period was from January 27, 2000 until June 6, 2000. The total exposure was for 14293 FPD (full power days). Reactor dosimetry capsules were analyzed and the activation data were used to provide the best estimates of the neutron fluences and radiation damage parameters as a function of height relative to midplane of the reactor.

  8. Neutron fluence influence upon electrical resistivity change and microstructure of Ti-Al alloy

    The influence of neutron fluence at an interval of 1.2·1020 / 1·1024 m-2 on electrical resistivity and microstructure of Ti+50at.%Al and Ti+50at.%Al+2at.%Zr alloys is investigated. Is established that in the studied interval of neutron fluence the linear dependence of electrical resistivity increase is observed. Its significance achieves for both alloys 123% at maximal fluence. However the rate of electrical resistivity change in 1.2 times is higher for an Ti+50at.%Al+2at.%Zr alloy, than for an Ti+50at.%Al alloy. Also it has been revealed that irradiation of the alloy composed of Ti+50at.%Al in the WWR-K reactor results in formation of depleted zones near dislocations and fine conglomerations of the radiation-induced defects, distributed homogeneously over the grain body. The main portion of the conglomerations represents fine dislocation loops of the size/density increasing with the neutron fluence increase. Contribution of radiation defects, visible by TEM, on electrical resistivity change of an Ti+50at.%Al alloy does not exceed 0.2%. Complete set of all obtained results allows to conclude that basic contribution to of electrical resistivity change of Ti+50at.%Al and Ti+50at.%Al+2at.%Zr alloys at a neutron irradiation is caused by formation of point defects, clusters and their complexes with impurities; doping the alloy Ti+50at.%Al by zirconium provides larger survivability for the defects of this type. The performed investigation has shown to sufficiently high phase-structure stability of the Ti-Al alloy subject to irradiation. In addition to a low residual radioactivity and fortune combination of the thermal, physical and mechanical properties that provide a low value of the thermal stress as well as a high value of the fatigue strength and the disruption viscosity, this circumstances makes it possible to consider titanium aluminides and the alloys on a base of titanium aluminides as reliable, novel constructional materials for nuclear/thermonuclear power

  9. Realization of fluence field modulated CT on a clinical TomoTherapy megavoltage CT system

    The multi-leaf collimator (MLC) assembly present on TomoTherapy (Accuray, Madison WI) radiation therapy (RT) and mega voltage CT machines is well suited to perform fluence field modulated CT (FFMCT). In addition, there is a demand in the RT environment for FFMCT imaging techniques, specifically volume of interest (VOI) imaging.A clinical TomoTherapy machine was programmed to perform VOI. Four different size ROIs were placed at varying distances from isocenter. Projections intersecting the VOI received ‘full dose’ while those not intersecting the VOI received 30% of the dose (i.e. the incident fluence for non VOI projections was 30% of the incident fluence for projections intersecting the VOI). Additional scans without fluence field modulation were acquired at ‘full’ and 30% dose. The noise (pixel standard deviation) and mean CT number were measured inside the VOI region and compared between the three scans. Dose maps were generated using a dedicated TomoTherapy treatment planning dose calculator.The VOI-FFMCT technique produced an image noise 1.05, 1.00, 1.03, and 1.05 times higher than the ‘full dose’ scan for ROI sizes of 10 cm, 13 cm, 10 cm, and 6 cm respectively within the VOI region. The VOI-FFMCT technique required a total imaging dose equal to 0.61, 0.69, 0.60, and 0.50 times the ‘full dose’ acquisition dose for ROI sizes of 10 cm, 13 cm, 10 cm, and 6 cm respectively within the VOI region.Noise levels can be almost unchanged within clinically relevant VOIs sizes for RT applications while the integral imaging dose to the patient can be decreased, and/or the image quality in RT can be dramatically increased with no change in dose relative to non-FFMCT RT imaging. The ability to shift dose away from regions unimportant for clinical evaluation in order to improve image quality or reduce imaging dose has been demonstrated. This paper demonstrates that FFMCT can be performed using the MLC on a clinical TomoTherapy machine for the

  10. The effect of crystal orientation on damage accumulation in chromium-implanted Al2O3

    Chromium-implantation of single crystal aluminium oxide (Al2O3) has been shown to be anisotropic with respect to damage accumulation. Ultra-low load indentation and Rutherford Backscattering Spectroscopy (RBS) have been used to demonstrate the dependence of radiation damage on fluence and crystal orientation. Single crystal Al2O3 specimens of c-axis ([0001] normal to the surface) and a-axis ([1120] normal to the surface) orientations were ion-implanted simultaneously and found to possess different near-surface mechanical properties. Subsequent RBS-ion channeling examination indicated different amounts of disorder in both the aluminum and oxygen sublattices for the two orientations. These results imply a higher amorphization threshold in terms of implantation fluence for the a-axis oriented samples. 15 refs., 6 figs

  11. Calculation of neutron fluence-to-dose conversion factors for extremities

    The Pacific Northwest Laboratory (PNL) is developing a standard for the performance testing of personnel extremity dosemeters for the US Department of Energy (DOE). Part of this effort requires the calculation of neutron fluence-to-dose conversion factors for finger and wrist/ankle extremities. This study focuses on conversion factors for two types of extremity models: (1) the polymethyl methacrylate (PMMA) phantom (as specified in the draft standard for performance testing of extremity dosemeters) and (2) more realistic extremity models composed of tissue and bone. Calculations for each type of model are based on both bare and D2O-moderated 252Cf sources. The results are then tabulated and compared with whole-body conversion factors. More appropriate average quality factors for the extremity models have also been computed from the energy dependent neutron fluence. Tabulated results show that conversion factors for both types of extremity phantoms are 3 to 28% lower than the corresponding whole-body phantom conversion factors for 252Cf neutron sources. This difference in extremity and whole-body conversion factors is attributable to the proportionally smaller amount of scattering that occurs in the extremity phantoms compared to whole-body phantoms. (author)

  12. Monte Carlo transport calculations and analysis for reactor pressure vessel neutron fluence

    The application of Monte Carlo methods for reactor pressure vessel (RPV) neutron fluence calculations is examined. As many commercial nuclear light water reactors approach the end of their design lifetime, it is of great consequence that reactor operators and regulators be able to characterize the structural integrity of the RPV accurately for financial reasons, as well as safety reasons, due to the possibility of plant life extensions. The Monte Carlo method, which offers explicit three-dimensional geometric representation and continuous energy and angular simulation, is well suited for this task. A model of the Three Mile Island unit 1 reactor is presented for determination of RPV fluence; Monte Carlo (MCNP) and deterministic (DORT) results are compared for this application; and numerous issues related to performing these calculations are examined. Synthesized three-dimensional deterministic models are observed to produce results that are comparable to those of Monte Carlo methods, provided the two methods utilize the same cross-section libraries. Continuous energy Monte Carlo methods are shown to predict more (15 to 20%) high-energy neutrons in the RPV than deterministic methods

  13. Measuring neutron fluences and gamma/x-ray fluxes with CCD cameras

    The capability to measure bursts of neutron fluences and gamma/x-ray fluxes directly with charge coupled device (CCD) cameras while being able to distinguish between the video signals produced by these two types of radiation, even when they occur simultaneously, has been demonstrated. Volume and area measurements of transient radiation-induced pixel charge in English Electric Valve (EEV) Frame Transfer (FT) charge coupled devices (CCDs) from irradiation with pulsed neutrons (14 MeV) and Bremsstrahlung photons (4--12 MeV endpoint) are utilized to calibrate the devices as radiometric imaging sensors capable of distinguishing between the two types of ionizing radiation. Measurements indicate ∼.05 V/rad responsivity with ≥1 rad required for saturation from photon irradiation. Neutron-generated localized charge centers or ''peaks'' binned by area and amplitude as functions of fluence in the 105 to 107 n/cm2 range indicate smearing over ∼1 to 10% of CCD array with charge per pixel ranging between noise and saturation levels

  14. Calculation of neutron fluence-to-dose conversion factors for extremities

    The Pacific Northwest Laboratory is developing a standard for the performance testing of personnel extremity dosimeters for the US Department of Energy. Part of this effort requires the calculation of neutron fluence-to-dose conversion factors for finger and wrist extremities. This study focuses on conversion factors for two types of extremity models: namely the polymethyl methacrylate (PMMA) phantom (as specified in the draft standard for performance testing of extremity dosimeters) and more realistic extremity models composed of tissue-and-bone. Calculations for each type of model are based on both bare and D2O-moderated 252Cf sources. The results are then tabulated and compared with whole-body conversion factors. More appropriate energy-averaged quality factors for the extremity models have also been computed from the neutron fluence in 50 equally spaced energy bins with energies from 2.53 x 10-8 to 15 MeV. Tabulated results show that conversion factors for both types of extremity phantom are 15 to 30% lower than the corresponcung whole-body phantom conversion factors for 252Cf neutron sources. This difference in extremity and whole-body conversion factors is attributable to the proportionally smaller amount of back-scattering that occurs in the extremity phantoms compared with whole-body phantoms

  15. Neutron fluence rate measurements in a PGNAA 208-liter drum assay system using silicon carbide detectors

    Dulloo, A.R. E-mail: dullooar@westinghouse.com; Ruddy, F.H.; Seidel, J.G.; Lee, S.; Petrovic, B.; McIlwain, M.E

    2004-01-01

    Pulsed prompt gamma neutron activation analysis (PGNAA) is being implemented for the nondestructive assay (NDA) of mercury, cadmium and lead in containers of radioactive waste. A PGNAA prototype system capable of assaying 208-liter (55-gallon) drums has already been built and demonstrated. As part of the evaluation of this system, the thermal neutron fluence rate distribution in a drum containing a combustible waste surrogate was measured during PGNAA runs using a silicon carbide neutron detector. The fast charge-collection time of this detector type enabled the investigation of the neutron kinetics at various locations within the matrix during and between pulses of the system's 14-MeV neutron source. As expected, the response of a SiC detector equipped with a lithium-6 fluoride layer is dominated by thermal neutron-induced events between pulses. The measurement results showed that the thermal neutron fluence rate is relatively uniform over a radial depth of several centimeters in the matrix region that contributes a significant fraction of the prompt gamma radiation incident on the system's photon detector.

  16. Neutron fluence rate measurements in a PGNAA 208-liter drum assay system using silicon carbide detectors

    Dulloo, A. R.; Ruddy, F. H.; Seidel, J. G.; Lee, S.; Petrović, B.; McIlwain, M. E.

    2004-01-01

    Pulsed prompt gamma neutron activation analysis (PGNAA) is being implemented for the nondestructive assay (NDA) of mercury, cadmium and lead in containers of radioactive waste. A PGNAA prototype system capable of assaying 208-liter (55-gallon) drums has already been built and demonstrated. As part of the evaluation of this system, the thermal neutron fluence rate distribution in a drum containing a combustible waste surrogate was measured during PGNAA runs using a silicon carbide neutron detector. The fast charge-collection time of this detector type enabled the investigation of the neutron kinetics at various locations within the matrix during and between pulses of the system's 14-MeV neutron source. As expected, the response of a SiC detector equipped with a lithium-6 fluoride layer is dominated by thermal neutron-induced events between pulses. The measurement results showed that the thermal neutron fluence rate is relatively uniform over a radial depth of several centimeters in the matrix region that contributes a significant fraction of the prompt gamma radiation incident on the system's photon detector.

  17. Neutron fluence rate measurements in a PGNAA 208-liter drum assay system using silicon carbide detectors

    Pulsed prompt gamma neutron activation analysis (PGNAA) is being implemented for the nondestructive assay (NDA) of mercury, cadmium and lead in containers of radioactive waste. A PGNAA prototype system capable of assaying 208-liter (55-gallon) drums has already been built and demonstrated. As part of the evaluation of this system, the thermal neutron fluence rate distribution in a drum containing a combustible waste surrogate was measured during PGNAA runs using a silicon carbide neutron detector. The fast charge-collection time of this detector type enabled the investigation of the neutron kinetics at various locations within the matrix during and between pulses of the system's 14-MeV neutron source. As expected, the response of a SiC detector equipped with a lithium-6 fluoride layer is dominated by thermal neutron-induced events between pulses. The measurement results showed that the thermal neutron fluence rate is relatively uniform over a radial depth of several centimeters in the matrix region that contributes a significant fraction of the prompt gamma radiation incident on the system's photon detector

  18. Photon fluence-to-effective dose conversion coefficients calculated from a Saudi population-based phantom

    Ma, A. K.; Altaher, K.; Hussein, M. A.; Amer, M.; Farid, K. Y.; Alghamdi, A. A.

    2014-02-01

    In this work we will present a new set of photon fluence-to-effective dose conversion coefficients using the Saudi population-based voxel phantom developed recently by our group. The phantom corresponds to an average Saudi male of 173 cm tall weighing 77 kg. There are over 125 million voxels in the phantom each of which is 1.37×1.37×1.00 mm3. Of the 27 organs and tissues of radiological interest specified in the recommendations of ICRP Publication 103, all but the oral mucosa, extrathoracic tissue and the lymph nodes were identified in the current version of the phantom. The bone surface (endosteum) is too thin to be identifiable; it is about 10 μm thick. The dose to the endosteum was therefore approximated by the dose to the bones. Irradiation geometries included anterior-posterior (AP), left (LLAT) and rotational (ROT). The simulations were carried out with the MCNPX code version 2.5.0. The fluence in free air and the energy depositions in each organ were calculated for monoenergetic photon beams from 10 keV to 10 MeV to obtain the conversion coefficients. The radiation and tissue weighting factors were taken from ICRP Publication 60 and 103. The results from this study will also be compared with the conversion coefficients in ICRP Publication 116.

  19. Active waveguides by low-fluence carbon implantation in Nd3+-doped fluorophosphate glasses

    Liu, Chun-Xiao; Luo, Zhe-Yuan; Li, Yu-Wen; Chen, Meng; Xu, Jun; Fu, Li-Li; Yu, Ke-Han; Zheng, Rui-Lin; Zhou, Zhi-Guang; Li, Wei-Nan; Guo, Hai-Tao; Lin, She-Bao; Wei, Wei

    2016-01-01

    A planar waveguide in the Nd3+-doped fluorophosphate glass is fabricated by a 6.0 MeV C3+ ion implantation at a low-fluence of 1.0 × 1014 ions/cm2. The fluence is close to that in semiconductor industry. The dark mode spectra are recorded by a model 2010 prism coupler. The energy losses during the implantation process and the refractive index profile of the waveguide are simulated by the SRIM 2010 code and the reflectivity calculation method (RCM), respectively. The near-field light intensity profile and the propagation loss of the waveguide are measured by an end-face coupling system. The two-dimensional (2D) modal profile of transverse electric (TE) mode for the fabricated waveguide is calculated by the finite difference beam propagation method (FD-BPM). The results of microluminescence and optical absorption reveal that the spectroscopic characteristics of the Nd3+-doped fluorophosphate glass are nearly unaffected by the carbon ion implantation process. This work suggests that the carbon-implanted Nd3+-doped fluorophosphate glass waveguide is a promising candidate for integrated active devices.

  20. The characterization of PEEK, PET and PI implanted with Co ions to high fluences

    Polyimide (PI), polyetheretherketone (PEEK), and polyethylene terephthalate (PET) foils have been implanted with 40 keV Co+ ions at room temperature to the fluences ranging from 0.2 × 1016 cm−2 to 1.0 × 1017 cm−2. Co depth profiles determined by RBS have been compared to SRIM 2008 calculations. The measured projected ranges RP differ slightly from the SRIM simulation because of the compositional changes in polymers implanted to high fluences; especially the widths of the Co profiles are much larger than those simulated by SRIM. Oxygen and hydrogen depletion has been examined using the RBS and ERDA techniques. The surface morphology of the implanted polymers has been characterized using AFM. The PET polymer exhibits lower oxygen escape than the PI and PEEK, but the surface roughness at PET has been affected most significantly after the implantation. Implanted Co atoms tend to aggregate into nanoparticles, the size and distribution of which has been determined from TEM micrographs and using image analysis. The largest diameter of Co particles has been found in implanted PET.

  1. Signal and noise of Diamond Pixel Detectors at High Radiation Fluences

    Tsung, Jieh-Wen; Hügging, Fabian; Kagan, Harris; Krüger, Hans; Wermes, Norbert

    2012-01-01

    CVD diamond is an attractive material option for LHC vertex detectors because of its strong radiation-hardness causal to its large band gap and strong lattice. In particular, pixel detectors operating close to the interaction point profit from tiny leakage currents and small pixel capacitances of diamond resulting in low noise figures when compared to silicon. On the other hand, the charge signal from traversing high energy particles is smaller in diamond than in silicon by a factor of about 2.2. Therefore, a quantitative determination of the signal-to-noise ratio (S/N) of diamond in comparison with silicon at fluences in excess of 10$^{15}$ n$_{eq}$ cm$^{-2}$, which are expected for the LHC upgrade, is important. Based on measurements of irradiated diamond sensors and the FE-I4 pixel readout chip design, we determine the signal and the noise of diamond pixel detectors irradiated with high particle fluences. To characterize the effect of the radiation damage on the materials and the signal decrease, the chang...

  2. Embrittlement of Cr-Mo steels after low fluence irradiation in HFIR

    Klueh, R.L.; Alexander, D.J.

    1995-04-01

    The goal of this work is the determination of the possible effect of the simultaneous formation of helium and displacement damage during irradiation on the Charpy impact behavior. Subsize Charpy impact specimens of 9Cr-1MoVNb (modified 9Cr-1Mo) and 12Cr-1MoVW (Sandvik HT9) steels and 12Cr-1MoVW with 2%Ni (12Cr-1MOVW-2Ni) were irradiated in the High Flux Isotope Reactor (HFIR) at 300 and 400{degree}C to damage levels up to 2.5 dpa. The objective was to study the effect of the simultaneous formation of displacement damage and transmutation helium on impact toghness. Despite the low fluence relative to previous irradiations of these steels, significant increases in the ductile-brittle transition temperature (DBTT) occurred. The 12Cr-1MoVW-2Ni steel irradiated at 400{degree}C had the largest increase in DBTT and displayed indications of intergranular fracture. A mechanism is proposed to explain how helium can affect the fracture behaviour of this latter steel in the present tests, and how it affected all three steels in previous experiments, where the steels were irradiated to higher fluences.

  3. Laser ablation of thin molybdenum films on transparent substrates at low fluences

    The selective structuring of thin molybdenum (Mo) films is a major challenge for the monolithic interconnection of CIS thin film solar cells during their production. Here we present the structuring of ca. 0.5 μm thin molybdenum films on glass substrates with picosecond laser pulses (pulse duration 10 ps, wavelength 1064 nm) without any visible thermal effect on both, the remaining film and the substrate material. When the molybdenum film is irradiated from the transparent substrate side with a fluence level below 1 J/cm2 a ''lift-off'' process is initiated, which seems to be induced by a direct effect in the removed molybdenum film. At that fluence level, the energy input per ablated volume of ca. 30 J/mm3 is much less than would be needed for a thermodynamic heating, melting and vaporization of the complete film with ca. 78 J/mm3. Therefore we conclude that the molybdenum is only evaporated partially. Parts of the ablated Mo-film can be found as structurally intact debris. We assume that partial melting and vaporization with high-pressure formation play an important role during that picosecond laser ablation without thermal side effects. Due to its remarkable physical nature we called that process ''directly induced laser ablation''. (orig.)

  4. Properties of polyimide, polyetheretherketone and polyethyleneterephthalate implanted by Ni ions to high fluences

    Malinsky, P. [Nuclear Physics Institute, Academy of Sciences of the Czech Republic v.v.i., 250 68 Rez (Czech Republic); Department of Physics, Faculty of Science, J.E. Purkinje University, 400 96 Usti nad Labem (Czech Republic); Mackova, A., E-mail: mackova@ujf.cas.cz [Nuclear Physics Institute, Academy of Sciences of the Czech Republic v.v.i., 250 68 Rez (Czech Republic); Department of Physics, Faculty of Science, J.E. Purkinje University, 400 96 Usti nad Labem (Czech Republic); Hnatowicz, V. [Nuclear Physics Institute, Academy of Sciences of the Czech Republic v.v.i., 250 68 Rez (Czech Republic); Khaibullin, R.I.; Valeev, V.F. [Radiation Physics Laboratory, Kazan Physical-Technical Institute, 420029 Kazan (Russian Federation); Slepicka, P.; Svorcik, V. [Department of Solid State Engineering, Institute of Chemical Technology, 166 28 Prague (Czech Republic); Slouf, M. [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 6 Prague (Czech Republic); Perina, V. [Nuclear Physics Institute, Academy of Sciences of the Czech Republic v.v.i., 250 68 Rez (Czech Republic)

    2012-02-01

    Polyimide (PI), polyetheretherketone (PEEK) and polyethyleneterephthalate (PET) were implanted with 40 keV Ni{sup +} ions at RT to the fluences (0.25-1.5) Multiplication-Sign 10{sup 17} cm{sup -2} at ion current density of 4 {mu}A cm{sup -2}. Then some of the samples were annealed at the temperatures close to the polymer glassy transition temperature. Depth profiles of the Ni atoms in the as implanted and annealed samples were determined by RBS method. The profiles in the as implanted samples agree reasonably with those simulated using TRYDIN code. The implanted Ni atoms tend to aggregate into nano-particles, the size and distribution of which was determined from TEM images. The nano-particle size increases with increasing ion fluence. Subsequent annealing leads to a reduction in the nanoparticle size. The surface morphology of the implanted and annealed samples was studied using AFM. The changes in the polymer sheet resistance of the implanted and annealed samples were measured by standard two-point technique. The sheet resistance decreases with increasing temperature of annealing.

  5. Time changes of vertical profile of neutron fluence rate in LVR-15 reactor

    The LVR-15 reactor is a light water research type reactor, which is situated, in Nuclear Research Institute, Rez near Prague. The reactor is used as a multipurpose facility. For some experiments and material productions, e.g. for homogeneity of silicon resistance in production of radiation doped silicon, the time changes of vertical profile of neutron fluence rate are particularly important. The assembly used for silicon irradiation has two self-powered neutron detectors installed in a vertical irradiation channel in LVR-15 reactor. Vertical profile of thermal neutron fluence rate was automatically scanned during reactor operation. The results of measurements made in 2002 and 2003 with these detectors are presented. A set of vertical profile measurements was made during two 21-days reactor cycles. During the cycle the vertical profile slightly changes both in the position of its maximum and in the shape. The time dependences of the position of profile maximum and the profile width at half maximum during the cycle are given. (author)

  6. Propensity and Risk Assessment for Solar Particle Events: Consideration of Integral Fluence at High Proton Energies

    Kim, Myung-Hee; Hayat, Matthew J.; Feiveson, alan H.; Cucinotta, Francis A.

    2008-01-01

    For future space missions with longer duration, exposure to large solar particle events (SPEs) with high energy levels is the major concern during extra-vehicular activities (EVAs) on the lunar and Mars surface. The expected SPE propensity for large proton fluence was estimated from a non-homogeneous Poisson model using the historical database for measurements of protons with energy > 30 MeV, Phi(sub 30). The database includes a continuous data set for the past 5 solar cycles. The resultant SPE risk analysis for a specific mission period was made including the 95% confidence level. In addition to total particle intensity of SPE, the detailed energy spectra of protons especially at high energy levels were recognized as extremely important parameter for the risk assessment, since there remains a significant cancer risks from those energetic particles for large events. Using all the recorded proton fluence of SPEs for energies >60 and >100 MeV, Phi(sub 60) and Phi(sub 100), respectively, the expected propensities of SPEs abundant with high energy protons were estimated from the same non-homogeneous Poisson model and the representative cancer risk was analyzed. The dependencies of risk with different energy spectra, for e.g. between soft and hard SPEs, were evaluated. Finally, we describe approaches to improve radiation protection of astronauts and optimize mission planning for future space missions.

  7. Hiroshima neutron fluence on a glass button from near ground zero.

    Fleischer, R L; Fujita, S; Hoshi, M

    2001-12-01

    A decorative glass button that was uncovered at a location that is 190 +/- 15 m from directly beneath the atomic explosion at Hiroshima on 6 August 1945 has been scanned for induced fission tracks produced mostly by the thermal neutrons from the bomb due to interactions with the trace uranium that is normally present in silicate glasses. In surveying 4.14 cm2 at 500x magnification, 28 tracks were seen. From a calibration irradiation in a nuclear reactor we infer that the neutron fluence in 1945 was 5.7(+/-1.1) x 10(11) cm(-2); and, allowing for shielding by the structure in which the button was probably located, the free-air (i.e., outside) value is estimated as 1.5(+/-0.5) x 10(12) cm(-2). A limit has been placed on possible fading of the radiation-damage tracks that could increase the fluence by at most a factor of 1.27. The values bracket the calculated value of 9 x 10(11) given in DS86 but are higher than the 3.6 x 10(11) inferred from induced radionuclides for the distance given. The difference is, however, within the observed variability of the two types of results. PMID:11725892

  8. Characterization of 235U targets for the development of a secondary neutron fluence standard

    The MetroFission project, a Joint Research Project within the European Metrology Research Program, aims at addressing a number of metrological problems involved in the design of proposed Generation IV nuclear reactors. As part of this project a secondary neutron fluence standard is being developed and tested at the neutron time-of-flight facility GELINA of the JRCs Institute for Reference Materials and Measurements. Such a secondary standard will help to arrive at the neutron cross section measurement uncertainties required for the design and safety assessment of new generation power plants and fuel cycles. Such a neutron fluence device contains targets for which the neutron induced cross section is considered to be a standard. A careful preparation and characterization of these samples is an essential part of the development of the secondary standard. In this framework a set of 235U targets has been produced by vapour deposition of UF4 on aluminium backings by IRMMs target preparation laboratory. These targets have been characterized for both their total mass and mass distribution over the sample area. (author)

  9. Ice slurry accumulation

    Christensen, K.G.; Kauffeld, M.

    1998-06-01

    More and more refrigeration systems are designed with secondary loops, thus reducing the refrigerant charge of the primary refrigeration plant. In order not to increase energy consumption by introducing a secondary refrigerant, alternatives to the well established single phase coolants (brines) and different concepts of the cooling plant have to be evaluated. Combining the use of ice-slurry - mixture of water, a freezing point depressing agent (antifreeze) and ice particles - as melting secondary refrigerant and the use of a cool storage makes it possible to build plants with secondary loops without increasing the energy consumption and investment. At the same time the operating costs can be kept at a lower level. The accumulation of ice-slurry is compared with other and more traditional storage systems. The method is evaluated and the potential in different applications is estimated. Aspects of practically use of ice-slurry has been examined in the laboratory at the Danish Technological Institute (DTI). This paper will include the final conclusions from this work concerning tank construction, agitator system, inlet, outlet and control. The work at DTI indicates that in some applications systems with ice-slurry and accumulation tanks have a great future. These applications are described by a varying load profile and a process temperature suiting the temperature of ice-slurry (-3 - -8/deg. C). (au)

  10. The Antiproton Accumulator (AA)

    1980-01-01

    Section 06 - 08*) of the AA where the dispersion (and hence the horizontal beam size) is large. One can distinguish (left to right): A vacuum-tank, two bending magnets (BST06 and BST07 in blue) with a quadrupole (QDN07, in red) in between, another vacuum-tank, a wide quadrupole (QFW08) and a further tank . The tanks are covered with heating tape for bake-out. The tank left of BST06 contained the stack core pickup for stochastic cooling (see 7906193, 7906190, 8005051), the two other tanks served mainly as vacuum chambers in the region where the beam was large. Peter Zettwoch works on BST06. *) see: H. Koziol, Antiproton Accumulator Parameter List, PS/AA/Note 84-2 (1984)

  11. Solids Accumulation Scouting Studies

    Duignan, M. R.; Steeper, T. J.; Steimke, J. L.

    2012-09-26

    The objective of Solids Accumulation activities was to perform scaled testing to understand the behavior of remaining solids in a Double Shell Tank (DST), specifically AW-105, at Hanford during multiple fill, mix, and transfer operations. It is important to know if fissionable materials can concentrate when waste is transferred from staging tanks prior to feeding waste treatment plants. Specifically, there is a concern that large, dense particles containing plutonium could accumulate in poorly mixed regions of a blend tank heel for tanks that employ mixing jet pumps. At the request of the DOE Hanford Tank Operations Contractor, Washington River Protection Solutions, the Engineering Development Laboratory of the Savannah River National Laboratory performed a scouting study in a 1/22-scale model of a waste staging tank to investigate this concern and to develop measurement techniques that could be applied in a more extensive study at a larger scale. Simulated waste tank solids: Gibbsite, Zirconia, Sand, and Stainless Steel, with stainless steel particles representing the heavier particles, e.g., plutonium, and supernatant were charged to the test tank and rotating liquid jets were used to mix most of the solids while the simulant was pumped out. Subsequently, the volume and shape of the mounds of residual solids and the spatial concentration profiles for the surrogate for heavier particles were measured. Several techniques were developed and equipment designed to accomplish the measurements needed and they included: 1. Magnetic particle separator to remove simulant stainless steel solids. A device was designed and built to capture these solids, which represent the heavier solids during a waste transfer from a staging tank. 2. Photographic equipment to determine the volume of the solids mounds. The mounds were photographed as they were exposed at different tank waste levels to develop a composite of topographical areas. 3. Laser rangefinders to determine the volume of

  12. Electrical characteristics and charge collection efficiency of silicon detectors irradiated with very high neutron and proton fluences

    Measurements performed on high resistivity silicon detectors irradiated with proton and neutron fluences, up to 3.5 x 1014 p/cm2 and 4.0 x 1015 n/cm2 respectively, are presented. The current-voltage (IV) and capacitance-voltage (CV) characteristics, as well as the charge collection efficiency (CCE) of the devices have been measured to carry out a complete detector performance analysis after irradiation. The IV, CV and CCE analyses show that the irradiated devices depart from the ideal p+n junction modelisation when the fluence (f) is of the order of 1014-1015 cm-2. In this fluence range, it is impossible to fully deplete the irradiated device; the CV characteristics show evidence of full depletion voltages up to 103-104 Volts; the IV and CCE(V) curves are found to be linear in this fluence range; reverse currents up to a few mA are measured. A well visible, although low, charge collection signal has been observed at 7 C after exposure to the extreme irradiation fluence of 4.0 x 1015 n/cm2. This is probably due to a very narrow active region inside the semiconductor bulk, and corresponding approximately, to a 75% inefficiency in the detector performance. (orig.)

  13. Light Water Reactor Sustainability Program BWR High-Fluence Material Project: Assessment of the Role of High-Fluence on the Efficiency of HWC Mitigation on SCC Crack Growth Rates

    Sebastien Teysseyre

    2014-04-01

    As nuclear power plants age, the increasing neutron fluence experienced by stainless steels components affects the materials resistance to stress corrosion cracking and fracture toughness. The purpose of this report is to identify any new issues that are expected to rise as boiling water reactor power plants reach the end of their initial life and to propose a path forward to study such issues. It has been identified that the efficiency of hydrogen water chemistry mitigation technology may decrease as fluence increases for high-stress intensity factors. This report summarizes the data available to support this hypothesis and describes a program plan to determine the efficiency of hydrogen water chemistry as a function of the stress intensity factor applied and fluence. This program plan includes acquisition of irradiated materials, generation of material via irradiation in a test reactor, and description of the test plan. This plan offers three approaches, each with an estimated timetable and budget.

  14. Creation of an atlas of filter positions for fluence field modulated CT

    Szczykutowicz, Timothy P., E-mail: TSzczykutowicz@uwhealth.org [Departments of Radiology and Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin 53705 (United States); Hermus, James [Department of Biomedical Engineering, University of Wisconsin-Madison, 1550 Engineering Drive, Madison, Wisconsin 53706 (United States)

    2015-04-15

    Purpose: Fluence field modulated CT (FFMCT) and volume of interest (VOI) CT imaging applications require adjustment of the profile of the x-ray fluence incident on a patient as a function of view angle. Since current FFMCT prototypes can theoretically take on an infinite number of configurations, measuring a calibration data set for all possible positions would not be feasible. The present work details a methodology for calculating an atlas of configurations that will span all likely body regions, patient sizes, patient positioning, and imaging modes. The hypothesis is that there exists a finite number of unique modulator configurations that effectively span the infinite number of possible fluence profiles with minimal loss in performance. Methods: CT images of a head, shoulder, thorax, abdominal, wrist, and leg anatomical slices were dilated and contracted to model small, medium, and large sized patients. Additionally, the images were positioned from iso-center by three different amounts. The modulator configurations required to compensate for each image were computed assuming a FFMCT prototype, digital beam attenuator, (DBA), was set to equalize the detector exposure. Each atlas configuration should be different from the other atlas configurations. The degree of difference was quantified using the sum of the absolute differences in filter thickness between configurations. Using this metric, a set of unique wedge configurations for which no two configurations have a metric value smaller than some threshold can be constructed. Differences in the total number of incident photons between the unconstrained filters and the atlas were studied as a function of the number of atlas positions for each anatomical site and size/off-centering combination. Results: By varying the threshold used in creating the atlas, it was found that roughly 322 atlas positions provided an incident number of photons within 20% of using 19 440 unique filters (the number of atlas entries

  15. Realization of a scanning ion beam monitor

    During this thesis, a scanning ion beam monitor has been developed in order to measure on-line fluence spatial distributions. This monitor is composed of an ionization chamber, Hall Effect sensors and a scintillator. The ionization chamber set between the beam exit and the experiment measures the ion rate. The beam spot is localized thanks to the Hall Effect sensors set near the beam sweeping magnets. The scintillator is used with a photomultiplier tube to calibrate the ionization chamber and with an imaging device to calibrate the Hall Effect sensors. This monitor was developed to control the beam lines of a radiobiology dedicated experimentation room at GANIL. These experiments are held in the context of the research in hadron-therapy. As a matter of fact, this new cancer treatment technique is based on ion irradiations and therefore demands accurate knowledge about the relation between the dose deposit in biological samples and the induced effects. To be effective, these studies require an on-line control of the fluence. The monitor has been tested with different beams at GANIL. Fluence can be measured with a relative precision of ±4% for a dose rate ranging between 1 mGy/s and 2 Gy/s. Once permanently set on the beam lines dedicated to radiobiology at GANIL, this monitor will enable users to control the fluence spatial distribution for each irradiation. The scintillator and the imaging device are also used to control the position, the spot shape and the energy of different beams such as those used for hadron-therapy. (author)

  16. Naphthalene degradation in seawater by UV irradiation: the effects of fluence rate, salinity, temperature and initial concentration.

    Jing, Liang; Chen, Bing; Zhang, Baiyu; Zheng, Jisi; Liu, Bo

    2014-04-15

    A large amount of oil pollution at sea is produced by the operational discharge of oily wastewater. The removal of polycyclic aromatic hydrocarbons (PAHs) from such sources using UV irradiation has become attractive, yet the photolysis mechanism in seawater has remained unclear. This study examines the photodegradation kinetics of naphthalene in natural seawater through a full factorial design of experiments (DOE). The effects of fluence rate, salinity, temperature and initial concentration are investigated. Results show that fluence rate, temperature and the interaction between temperature and initial concentration are the most influential factors. An increase in fluence rate can linearly promote the photodegradation process. Salinity increasingly impedes the removal of naphthalene because of the existence of free-radical scavengers and photon competitors. The results will help understand the photolysis mechanism of PAHs and develop more effective methods for treating oily seawater generated from offshore industries. PMID:24576392

  17. Femtosecond laser-induced size reduction of carbon nanodots in solution: Effect of laser fluence, spot size, and irradiation time

    Photoluminescent carbon nanodots (C-dots) with size tunability and uniformity were fabricated in polyethylene glycol (PEG200N) solution using femtosecond laser ablation method. The size distributions and photoluminescence (PL) properties of C-dots are well controlled by adjusting the combined parameters of laser fluence, spot size, and irradiation time. The size reduction efficiency of the C-dots progressively increases with decreasing laser fluence and spot size. The optimal PL spectra are red-shifted and the quantum yields decrease with the increase in C-dots size, which could be attributed to the more complex surface functional groups attached on C-dots induced at higher laser fluence and larger spot size. Moreover, an increase in irradiation time leads to a decrease in size of C-dots, but long-time irradiation will result in the generation of complex functional groups on C-dots, subsequently the PL spectra are red-shifted

  18. Femtosecond laser-induced size reduction of carbon nanodots in solution: Effect of laser fluence, spot size, and irradiation time

    Nguyen, Vanthan [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab of Information Photonic Technique, School of Electronics and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); School of Chemistry and Physics Engineering, Le Quy Don Technical University, Hanoi 7EN-248 (Viet Nam); Yan, Lihe, E-mail: liheyan@mail.xjtu.edu.cn; Si, Jinhai; Hou, Xun [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab of Information Photonic Technique, School of Electronics and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China)

    2015-02-28

    Photoluminescent carbon nanodots (C-dots) with size tunability and uniformity were fabricated in polyethylene glycol (PEG{sub 200N}) solution using femtosecond laser ablation method. The size distributions and photoluminescence (PL) properties of C-dots are well controlled by adjusting the combined parameters of laser fluence, spot size, and irradiation time. The size reduction efficiency of the C-dots progressively increases with decreasing laser fluence and spot size. The optimal PL spectra are red-shifted and the quantum yields decrease with the increase in C-dots size, which could be attributed to the more complex surface functional groups attached on C-dots induced at higher laser fluence and larger spot size. Moreover, an increase in irradiation time leads to a decrease in size of C-dots, but long-time irradiation will result in the generation of complex functional groups on C-dots, subsequently the PL spectra are red-shifted.

  19. Simulation study on retention and reflection from tungsten carbide under high fluence of helium ions

    We have studied, by a Monte Carlo simulation code ACAT-DIFFUSE, the fluence-dependence of the amount of retained helium atoms in tungsten carbide at room temperature under helium ion bombardment. The retention behavior may be understood qualitatively in terms of irradiation-dependent diffusion coefficient assumed and range. The emission processes from tungsten carbide under helium ion irradiation derived were compared with each other. We have discussed the retention curves for incident energy of 5 keV at incident angles of 0deg and 80deg and of 500 eV at 0deg. The energy spectra of helium atoms reflected from tungsten carbide for incident energy of 500 eV at 0deg and 80deg were compared with those from graphite and tungsten. (author)

  20. Effect of Source Bandwidth, Focusing and Fluence on the Depth Of Cure in Polymer Dental Composites

    Pradhan, Ranjit; Melikechi, Noureddine; Eichmiller, Frederick

    2000-03-01

    Photo-curable polymer dental composites are widely used in restorative dental applications. These composites are typically cured using a conventional curing lamp with broad band visible irradiation between 400-500 nm. Argon ion laser-based sources are now available in dentistry for curing applications. This work reports on the dependence of depth of cure on the wavelength bandwidth, the focusing geometry and the irradiation fluence of the curing light source. The depth of cure resulting from a narrow band irradiation source such as the 488 line of the Argon ion laser is observed to be higher than that resulting from broadband irradiation sources such as the curing lamp or the multiline Argon ion laser with lines between 450-500 nm. For the same total irradiation energy deposited into the polymer a focused beam yields higher depth of cure than a non-focused beam.

  1. A Multigroup Method for the Calculation of Neutron Fluence with a Source Term

    Heinbockel, J. H.; Clowdsley, M. S.

    1998-01-01

    Current research on the Grant involves the development of a multigroup method for the calculation of low energy evaporation neutron fluences associated with the Boltzmann equation. This research will enable one to predict radiation exposure under a variety of circumstances. Knowledge of radiation exposure in a free-space environment is a necessity for space travel, high altitude space planes and satellite design. This is because certain radiation environments can cause damage to biological and electronic systems involving both short term and long term effects. By having apriori knowledge of the environment one can use prediction techniques to estimate radiation damage to such systems. Appropriate shielding can be designed to protect both humans and electronic systems that are exposed to a known radiation environment. This is the goal of the current research efforts involving the multi-group method and the Green's function approach.

  2. Improvement of the High Fluence Irradiation Facility at the University of Tokyo

    Murakami, Kenta; Iwai, Takeo; Abe, Hiroaki; Sekimura, Naoto

    2016-08-01

    This paper reports the modification of the High Fluence Irradiation Facility at the University of Tokyo (HIT). The HIT facility was severely damaged during the 2011 earthquake, which occurred off the Pacific coast of Tohoku. A damaged 1.0 MV tandem Cockcroft-Walton accelerator was replaced with a 1.7 MV accelerator, which was formerly used in another campus of the university. A decision was made to maintain dual-beam irradiation capability by repairing the 3.75 MV single-ended Van de Graaff accelerator and reconstructing the related beamlines. A new beamline was connected with a 200 kV transmission electron microscope (TEM) to perform in-situ TEM observation under ion irradiation.

  3. Measurements on HV-CMOS Active Sensors After Irradiation to HL-LHC fluences

    Ristic, B

    2015-01-01

    During the long shutdown (LS) 3 beginning 2022 the LHC will be upgraded for higher luminosities pushing the limits especially for the inner tracking detectors of the LHC experiments. In order to cope with the increased particle rate and radiation levels the ATLAS Inner Detector will be completely replaced by a purely silicon based one. Novel sensors based on HV-CMOS processes prove to be good candidates in terms of spatial resolution and radiation hardness. In this paper measurements conducted on prototypes built in the AMS H18 HV-CMOS process and irradiated to fluences of up to $2\\cdot10^{16}\\,\\text{n}_\\text{eq}\\text{cm}^{-2}$ are presented.

  4. Damages of lower internals in high neutron fluence: materials assessment contributions

    Baffle jetting observed during the eighties has revealed baffle/former bolts cracking. If baffle jetting can be solved by UP FLOW conversion, bolts cracking is a problem for baffle plates behaviour. To understand the cracking mechanism, EDF approach consisted to determine the service conditions and the material properties after in service failure. A cartography of fluence, temperature and mechanical stresses was calculated for all the bolts. Destructive examinations included fractography, hardness and tensile tests, low strain rate stress corrosion tests, microstructural (TEM) and chemical analysis; these tests were performed on bolts extracted from Nuclear Units. On the basis of published data, all these results lead us to propose damaged mechanisms. (authors). 4 figs., 9 tabs., 11 refs

  5. Neutron dose per fluence and weighting factors for use at high energy accelerators

    Cossairt, J.Donald; Vaziri, Kamran; /Fermilab

    2008-07-01

    In June 2007, the United States Department of Energy incorporated revised values of neutron weighting factors into its occupational radiation protection Regulation 10 CFR Part 835 as part of updating its radiation dosimetry system. This has led to a reassessment of neutron radiation fields at high energy proton accelerators such as those at the Fermi National Accelerator Laboratory (Fermilab). Values of dose per fluence factors appropriate for accelerator radiation fields calculated elsewhere are collated and radiation weighting factors compared. The results of this revision to the dosimetric system are applied to americium-beryllium neutron energy spectra commonly used for instrument calibrations. A set of typical accelerator neutron energy spectra previously measured at Fermilab are reassessed in light of the new dosimetry system. The implications of this revision are found to be of moderate significance.

  6. Evaluation of fluence to dose equivalent conversion factors for high energy radiations, (2)

    Computer code system and basic data have been investigated for evaluating fluence to dose equivalent conversion factors for photons and neutrons up to 10 Gev. The present work suggested that the conversion factors would be obtained by incorporating effective quality factors of charged particles into the HERMES (High Energy Radiation Monte Carlo Elaborate System) code system. The evaluation method of the effective values of the quality factors for charged particles of human body elements were established on the basis of the Q-L relationships specified in the ICRP Publication 60 ; These effective quality factors for charged particles are essential to the calculation of the dose equivalent conversion factors for neutrons. Effective dose and dose equivalents on the principal axis of the ICRU sphere were also calculated by use of the EGS4 code in the HERMES code system. The availability of dose equivalents in the ICRU sphere were discussed on the comparison with dose equivalents for high energy photons. (author)

  7. A variable fluence step clustering and segmentation algorithm for step and shoot IMRT

    A step and shoot sequencer was developed that can be integrated into an IMRT optimization algorithm. The method uses non-uniform fluence steps and is adopted to the constraints of an MLC. It consists of a clustering, a smoothing and a segmentation routine. The performance of the algorithm is demonstrated for eight mathematical profiles of differing complexity and two optimized profiles of a clinical prostate case. The results in terms of stability, flexibility, speed and conformity fulfil the criteria for the integration into the optimization concept. The performance of the clustering routine is compared with another previously published one (Bortfeld et al 1994 Int. J. Radiat. Oncol. Biol. Phys. 28 723-30) and yields slightly better results in terms of mean and maximum deviation between the optimized and the clustered profile. We discuss the specific attributes of the algorithm concerning its integration into the optimization concept. (author)

  8. Monte Carlo neutron fluence calculations, activation measurements and spectrum adjustment for the KORPUS dosimetry experiment

    KORPUS is an irradiation facility located at the lateral core surface of the 6 MW experimental reactor RBT-6 in Dimitrovgrad. In this work the KORPUS irradiation experiment has been used to demonstrate the capability of the pressure vessel dosimetry methodology developed in Rossendorf to solve these problems. At the same time the experiments were used to test recent improvements of this methodology including a new procedure for treatment of elastic scattering in the Monte Carlo code TRAMO and a new multispectrum version of the adjustment code. By means of a series of calculations the influence of model and data approximations were investigated aiming at an evaluation of the uncertainties of the calculations. Further, uncertainty investigations were carried out in connection with spectrum adjustment resulting in covariances of spectra, measured reaction rates and fluence integrals. (orig.)

  9. Ultra-short laser ablation of dielectrics: Theoretical analysis of threshold damage fluence and ablation depth

    A coupled theoretical model based on Fokker-Planck equation for ultra-short laser ablation of dielectrics is proposed. Multiphoton ionization and avalanche ionization are considered as the sources during the generation of free electrons. The impact of the electron distribution in thermodynamic nonequilibrium on relaxation time is taken into account. The calculation formula of ablation depth is deduced based on the law of energy conservation. Numerical calculations are performed for the femtosecond laser ablation of fused silica at 526 and 1053 nm. It shows that the threshold damage fluences and ablation depths resulted from the coupled model are in good agreement with the experimental results; while the damage thresholds resulted from the approximate model significantly differ from the experimental results for lasers of long pulse width. It is concluded that the coupled model can better describe the micro-process of ultra-short laser ablation of dielectrics.

  10. Fluence measurement at the neutron time of flight experiment at CERN

    Weiss, Christina; Jericha, Erwin

    At the neutron time of flight facility n_TOF at CERN a new spallation target was installed in 2008. In 2008 and 2009 the commissioning of the new target took place. During the summer 2009 a fission chamber of the Physikalisch Technische Bundesanstalt (PTB) Braunschweig was used for the neutron fluence measurement. The evaluation of the data recorded with this detector is the primary topic of this thesis. Additionally a neutron transmission experiment with air has been performed at the TRIGA Mark II reactor of the Atomic Institute of the Austrian Universities (ATI). The experiment was implemented to clarify a question about the scattering cross section of molecular gas which could not be answered clearly via the literature. This problem came up during the evaluations for n_TOF.

  11. Material properties of lithium fluoride for predicting XUV laser ablation rate and threshold fluence

    Blejchař, Tomáś; Nevrlý, Václav; Vašinek, Michal; Dostál, Michal; Pečínka, Lukáś; Dlabka, Jakub; Stachoň, Martin; Juha, Libor; Bitala, Petr; Zelinger, Zdeněk.; Pira, Peter; Wild, Jan

    2015-05-01

    This paper deals with prediction of extreme ultraviolet (XUV) laser ablation of lithium fluoride at nanosecond timescales. Material properties of lithium fluoride were determined based on bibliographic survey. These data are necessary for theoretical estimation of surface removal rate in relevance to XUV laser desorption/ablation process. Parameters of XUV radiation pulses generated by the Prague capillary-discharge laser (CDL) desktop system were assumed in this context. Prediction of ablation curve and threshold laser fluence for lithium fluoride was performed employing XUV-ABLATOR code. Quasi-random sampling approach was used for evaluating its predictive capabilities in the means of variance and stability of model outputs in expected range of uncertainties. These results were compared to experimental data observed previously.

  12. The damage property of oxyfluoride glasses irradiated by a 351 nm high fluence laser

    The laser induced damage property of oxyfluoride glasses irradiated by a 351 nm laser has been investigated. Two kinds of oxyfluoride glass (oxyfluoride1 and oxyfluoride2) have been prepared by different preparation technologies and their LIDTs (laser induced damage thresholds) are 9.0 J cm−2 and 13.6 J cm−2 respectively. It is found that the variation of LIDT in oxyfluoride glasses is associated with photoluminescence originated structural defects. Decrease of the photoluminescence intensity in an oxyfluoride glass could improve the LIDT of the material. Meanwhile, an experiment on damage growth has been presented, and the damage growth of oxyfluoride glasses develops in the longitudinal direction of laser propagation, which causes the transmittance loss to be limited once the damage growth occurs. Moreover, the damage growth stops when the laser fluence is below 70% of the LIDT. (paper)

  13. Extension of CASCADE.04 to estimate neutron fluence and dose rates and its validation

    H Kumawat; V Kumar; P Srinivasan

    2009-03-01

    Capability to compute neutron dose rate is introduced for the first time in the new version of the CASCADE.04 code. Two different methods, `track length estimator' and `collision estimator' are adapted for the estimation of neutron fluence rate needed to calculate the ambient dose rate. For the validation of the methods, neutron dose rates are experimentally measured at different locations of a 5Ci Am–Be source, shielded in Howitzer-type system and these results are compared with those estimated using (i) modified CASCADE.04.d and (ii) MCNP4A codes and it is found that the agreement is good. The paper presents details of modification and results of the comparative study.

  14. Neutron fluences and dose equivalents measured with passive detectors on LDEF

    Frank, A. L.; Benton, E. V.; Armstrong, T. W.; Colborn, B. L.

    1996-01-01

    Neutron fluences were measured on LDEF in the low energy ( 1 MeV) ranges. The low energy detectors used the 6Li(n,alpha)T reaction with Gd foil absorbers to separate thermal (neutron response. High energy detectors contained sets of fission foils (181Ta, 209Bi, 232Th, 238U) with different neutron energy thresholds. The measured neutron fluences together with predicted spectral shapes were used to estimate neutron dose equivalents. The detectors were located in the A0015 and P0006 experiments at the west and Earth sides of LDEF under shielding varying from 1 to 19 g/cm2. Dose equivalent rates varied from 0.8 to 3.3 microSv/d for the low energy neutrons and from 160 to 390 microSv/d for the high energy neutrons. This compares with TLD measured absorbed dose rates in the range of 1000-3000 microGy/d near these locations and demonstrates that high energy neutrons contribute a significant fraction of the total dose equivalent in LEO. Comparisons between measurements and calculations were made for high energy neutrons based on fission fragment tracks generated by fission foils at different shielding depths. A simple 1-D slab geometry was used in the calculations. Agreement between measurements and calculations depended on both shielding depth and threshold energy of the fission foils. Differences increased as both shielding and threshold energy increased. The modeled proton/neutron spectra appeared deficient at high energies. A 3-D model of the experiments is needed to help resolve the differences.

  15. High Neutron Fluence Survivability Testing of Advanced Fiber Bragg Grating Sensors

    The motivation for the reported research was to support NASA space nuclear power initiatives through the development of advanced fiber optic sensors for space-based nuclear power applications. The purpose of the high-neutron fluence testing was to demonstrate the survivability of fiber Bragg grating (FBG) sensors in a fission reactor environment. 520 FBGs were installed in the Ford reactor at the University of Michigan. The reactor was operated for 1012 effective full power hours resulting in a maximum neutron fluence of approximately 5x1019 n/cm2, and a maximum gamma dose of 2x103 MGy gamma. This work is significant in that, to the knowledge of the authors, the exposure levels obtained are approximately 1000 times higher than for any previously published experiment. Four different fiber compositions were evaluated. An 87% survival rate was observed for fiber Bragg gratings located at the fuel centerline. Optical Frequency Domain Reflectometry (OFDR), originally developed at the NASA Langley Research Center, can be used to interrogate several thousand low-reflectivity FBG strain and/or temperature sensors along a single optical fiber. A key advantage of the OFDR sensor technology for space nuclear power is the extremely low mass of the sensor, which consists of only a silica fiber 125μm in diameter. The sensors produced using this technology will fill applications in nuclear power for current reactor plants, emerging Generation-IV reactors, and for space nuclear power. The reported research was conducted by Luna Innovations and was funded through a Small Business Innovative Research (SBIR) contract with the NASA Glenn Research Center

  16. MO-G-BRE-01: A Real-Time Virtual Delivery System for Photon Radiotherapy Delivery Monitoring

    Shi, F; Gu, X; Jiang, S; Jia, X [UT Southwestern Medical Center, Dallas, TX (United States); Graves, Y [University of California, San Diego, La Jolla, CA (United States)

    2014-06-15

    Purpose: Treatment delivery monitoring is important for radiotherapy, which enables catching dosimetric error at the earliest possible opportunity. This project develops a virtual delivery system to monitor the dose delivery process of photon radiotherapy in real-time using GPU-based Monte Carlo (MC) method. Methods: The simulation process consists of 3 parallel CPU threads. A thread T1 is responsible for communication with a linac, which acquires a set of linac status parameters, e.g. gantry angles, MLC configurations, and beam MUs every 20 ms. Since linac vendors currently do not offer interface to acquire data in real time, we mimic this process by fetching information from a linac dynalog file at the set frequency. Instantaneous beam fluence map (FM) is calculated. A FM buffer is also created in T1 and the instantaneous FM is accumulated to it. This process continues, until a ready signal is received from thread T2 on which an inhouse developed MC dose engine executes on GPU. At that moment, the accumulated FM is transferred to T2 for dose calculations, and the FM buffer in T1 is cleared. Once the calculation finishes, the resulting 3D dose distribution is directed to thread T3, which displays it in three orthogonal planes overlaid on the CT image for treatment monitoring. This process continues to monitor the 3D dose distribution in real-time. Results: An IMRT and a VMAT cases used in our patient-specific QA are studied. Maximum dose differences between our system and treatment planning system are 0.98% and 1.58% for the two cases, respectively. The average time per MC calculation is 0.1sec with <2% relative uncertainty. The update frequency of ∼10Hz is considered as real time. Conclusion: By embedding a GPU-based MC code in a novel data/work flow, it is possible to achieve real-time MC dose calculations to monitor delivery process.

  17. MO-G-BRE-01: A Real-Time Virtual Delivery System for Photon Radiotherapy Delivery Monitoring

    Purpose: Treatment delivery monitoring is important for radiotherapy, which enables catching dosimetric error at the earliest possible opportunity. This project develops a virtual delivery system to monitor the dose delivery process of photon radiotherapy in real-time using GPU-based Monte Carlo (MC) method. Methods: The simulation process consists of 3 parallel CPU threads. A thread T1 is responsible for communication with a linac, which acquires a set of linac status parameters, e.g. gantry angles, MLC configurations, and beam MUs every 20 ms. Since linac vendors currently do not offer interface to acquire data in real time, we mimic this process by fetching information from a linac dynalog file at the set frequency. Instantaneous beam fluence map (FM) is calculated. A FM buffer is also created in T1 and the instantaneous FM is accumulated to it. This process continues, until a ready signal is received from thread T2 on which an inhouse developed MC dose engine executes on GPU. At that moment, the accumulated FM is transferred to T2 for dose calculations, and the FM buffer in T1 is cleared. Once the calculation finishes, the resulting 3D dose distribution is directed to thread T3, which displays it in three orthogonal planes overlaid on the CT image for treatment monitoring. This process continues to monitor the 3D dose distribution in real-time. Results: An IMRT and a VMAT cases used in our patient-specific QA are studied. Maximum dose differences between our system and treatment planning system are 0.98% and 1.58% for the two cases, respectively. The average time per MC calculation is 0.1sec with <2% relative uncertainty. The update frequency of ∼10Hz is considered as real time. Conclusion: By embedding a GPU-based MC code in a novel data/work flow, it is possible to achieve real-time MC dose calculations to monitor delivery process

  18. Accumulation and transport mechanisms of arsenic in rice

    Islam, Md. Rafiqul; Kamiya, Takehiro; Uraguchi, Shimpei; Fujiwara, Toru

    2009-01-01

    Both species of arsenic (As), arsenate and arsenite are highly toxic to plants. Arsenic contamination is a major problem in Southeast Asia particularly in Bangladesh and West Bengal. In these countries, As-contaminated groundwater is widely used for irrigating rice in dry season that results in elevated As accumulation in soils and in rice grain and straw. So it is important for understanding the accumulation and transport mechanisms of arsenic in rice. We monitored increased arsenic content ...

  19. Accumulation of Ciprofloxacin and Minocycline by Cultured Human Gingival Fibroblasts

    Yang, Qing; Nakkula, Robin J.; Walters, John D.

    2002-01-01

    Through a mechanism that is unclear, systemic fluoroquinolones and tetracyclines can attain higher levels in gingival fluid than in blood. We hypothesized that gingival fibroblasts take up and accumulate these agents, thereby enhancing their redistribution to the gingiva. Using fluorescence to monitor transport activity, accumulation of fluoroquinolones and tetracyclines was characterized in cultured human gingival fibroblast monolayers. Both were transported in a concentrative, temperature-d...

  20. The Antiproton Accumulator (AA)

    1980-01-01

    A section of the AA where the dispersion (and hence the horizontal beam size) is large. One can distinguish (left to right): A large vacuum-tank, a quadrupole (QDN09*), a bending magnet (BST08), another vacuum-tank, a wide quadrupole (QFW08) and (in the background) a further bending magnet (BST08). The tanks are covered with heating tape for bake-out. The tank left of QDN09 contained the kickers for stochastic pre-cooling (see 790621, 8002234, 8002637X), the other one served mainly as vacuum chamber in the region where the beam was large. Peter Zettwoch works on QFW08. * see: H. Koziol, Antiproton Accumulator Parameter List, PS/AA/Note 84-2 (1984) See under 7911303, 7911597X, 8004261 and 8202324. For photos of the AA in different phases of completion (between 1979 and 1982) see: 7911303, 7911597X, 8004261, 8004608X, 8005563X, 8005565X, 8006716X, 8006722X, 8010939X, 8010941X, 8202324, 8202658X, 8203628X .

  1. The role of DNA-protein interaction in the UV damage of T7 bacteriophage at high fluences

    The influence of higher fluences (0.5-10 kJm-2) and that of phage protein coat on the UV (lambda = 254 nm) damage of T7 DNA were studied by UV difference spectroscopy. Beside the pyrimidine dimers and adducts produced also in isolated DNA in the case of intact phages and fluences exceeding 0.5 kJ m-2 other photoproducts, probably DNA-protein cross-links were identified as well. Phages deprived of their protein coat by a thermal treatment show similar UV damage to that of isolated DNA. (author)

  2. Determination of gamma dose and thermal neutron fluence in BNCT beams from the TLD-700 glow curve shape

    Gambarini, G., E-mail: grazia.gambarini@mi.infn.i [Universita degli Studi di Milano, Dipartimento di Fisica, via Celoria 16, 20133 Milano (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Milano, via Celoria 16, 20133 Milano (Italy); Bartesaghi, G. [Universita degli Studi di Milano, Dipartimento di Fisica, via Celoria 16, 20133 Milano (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Milano, via Celoria 16, 20133 Milano (Italy); Agosteo, S.; Vanossi, E. [Politecnico di Milano, Dipartimento di Energia, via Ponzio 34/3, 20133 Milano (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Milano, via Celoria 16, 20133 Milano (Italy); Carrara, M.; Borroni, M. [Fondazione IRCCS, Istituto Nazionale dei Tumori, Medical Physics Unit, via Venezian 1, 20133 Milano (Italy)

    2010-03-15

    The measurement of both gamma dose and thermal neutron fluence in a BNCT gamma-neutron mixed-field can be achieved by means of a single thermoluminescence dosimeter (TLD-700), exploiting the shape of the glow-curve (GC). The method is based on simple algorithms containing parameters obtained from the TLD-700 GC and requires the gamma calibration GC (for gamma dose measurement) or the thermal neutron calibration GC (for neutron fluence measurement) and moreover the GC of a TLD-600 exposed to a BNCT field, uncalibrated. Some results are reported, showing the potentiality of the method.

  3. Calculated spectral fluences and dosimeter activities for the metallurgical blind test irradiations at the ORR-PSF

    Fluence rate, fluence, and activity calculations were performed for each of the three exposures (two surveillance capsules and a pressure vessel capsule) performed during the two-year metallurgical blind test experiment at the ORR-Poolside Facility in Oak Ridge. Motivation for these calculations was prompted by differences of up to 25% between dosimetry measurements performed in the earlier startup scoping experiment and the two-year experiment. The calculations validate the trend of the measurements in both the startup and the two-year experiments, and confirm the presence of a significant cycle-to-cycle variation in the core leakage. (Auth.)

  4. RAMA Methodology for the Calculation of Neutron Fluence; Metodologia RAMA para el Calculo de la Fluencia Neutronica

    Villescas, G.; Corchon, F.

    2013-07-01

    he neutron fluence plays an important role in the study of the structural integrity of the reactor vessel after a certain time of neutron irradiation. The NRC defined in the Regulatory Guide 1.190, the way must be estimated neutron fluence, including uncertainty analysis of the validation process (creep uncertainty is ? 20%). TRANSWARE Enterprises Inc. developed a methodology for calculating the neutron flux, 1,190 based guide, known as RAMA. Uncertainty values obtained with this methodology, for about 18 vessels, are less than 10%.

  5. Batteries and accumulators in France

    The present report gives an overview of the batteries and accumulators market in France in 2011 based on the data reported through ADEME's Register of Batteries and accumulators. In 2001, the French Environmental Agency, known as ADEME, implemented a follow-up of the batteries and accumulators market, creating the Observatory of batteries and accumulators (B and A). In 2010, ADEME created the National Register of producers of Batteries and Accumulators in the context of the implementation of the order issued on November 18, 2009. This is one of the four enforcement orders for the decree 2009-1139 issued on September 22, 2009, concerning batteries and accumulators put on the market and the disposal of waste batteries and accumulators, and which transposes the EU-Directive 2006/66/CE into French law. This Register follows the former Observatory for batteries and accumulators. This Register aims to record the producers on French territory and to collect the B and A producers and recycling companies' annual reporting: the regulation indeed requires that all B and A producers and recycling companies report annually on the Register the quantities of batteries and accumulators they put on the market, collect and treat. Based on this data analysis, ADEME issues an annual report allowing both the follow-up of the batteries and accumulators market in France and communication regarding the achievement of the collection and recovery objectives set by EU regulation. This booklet presents the situation in France in 2011

  6. Analysis and comparison of monoenergetic fast neutron fluence determination using 238U samples at different positions with respect to the neutron source.

    Zhang, Guohui; Liu, Xiang; Gao, Zhiqi; Wu, Hao; Liu, Jiaming

    2012-05-01

    Using two (238)U samples placed in a gridded ionization chamber and a parallel-plate fission chamber, fluence of monoenergetic fast neutrons was determined. Four runs of measurements were performed. Analysis showed that although the neutron fluences for the two (238)U samples differ by 20-33 times in the present work, the fluences at the position of the sample in the gridded ionization chamber determined by the two ways are in agreement within experimental uncertainties. PMID:22398325

  7. A comparative study on efficacy of high and low fluence Q-switched Nd:YAG laser and glycolic acid peel in melasma

    Hemanta Kumar Kar; Lipy Gupta; Amrita Chauhan

    2012-01-01

    Background: Melasma is acquired symmetric hypermelanosis characterized by light-to-deep brown pigmentation over cheeks, forehead, upper lip, and nose. Treatment of this condition is difficult and associated with high recurrence rates. With the advent of newer therapies, there is interest in the use of glycolic acid peels and Q-switched Nd:YAG laser (QSNYL) in high and low fluence for this disorder. Aims: To compare the therapeutic efficacy of low fluence QSNYL, high fluence QSNYL, and glycoli...

  8. Beam diagnostics of the TRISTAN accumulation ring

    The beam diagnostic system of the TRISTAN Accumulation Ring consists of beam position monitors, visible radiation monitors, x-ray monitors, tune measurement setup, etc.. Eighty-six position monitors are installed around the ring. For the closed orbit measurement, a superheterodyne circuit is used to pick up the 479-th harmonic of the revolution frequency (795 kHz) out of beam pulse trains. Synchrotron light is observed in the visible region and in the x-ray region. Visible radiation is used in three ways: profile monitoring by TV cameras, beam current measurement and bunch shape observation by a streak camera. In the x-ray channel a multi-wire ionization chamber is used to get a digitized profile of the x-ray source. Stripline pickups are installed to detect transverse oscillations of e+ and e- bunches. The envelope signal of pulse trains will be sent to an FFT processor for tune number identification. At the same time the signals are amplified and fed back to wideband deflection electrodes for damping of the oscillaitons

  9. Resveratrol Prevents High Fluence Red Light-Emitting Diode Reactive Oxygen Species-Mediated Photoinhibition of Human Skin Fibroblast Migration.

    Andrew Mamalis

    Full Text Available Skin fibrosis is a significant medical problem that leads to a functional, aesthetic, and psychosocial impact on quality-of-life. Light-emitting diode-generated 633-nm red light (LED-RL is part of the visible light spectrum that is not known to cause DNA damage and is considered a safe, non-invasive, inexpensive, and portable potential alternative to ultraviolet phototherapy that may change the treatment paradigm of fibrotic skin disease.The goal of our study was to investigate the how reactive oxygen species (ROS free radicals generated by high fluence LED-RL inhibit the migration of skin fibroblasts, the main cell type involved in skin fibrosis. Fibroblast migration speed is increased in skin fibrosis, and we studied cellular migration speed of cultured human skin fibroblasts as a surrogate measure of high fluence LED-RL effect on fibroblast function. To ascertain the inhibitory role of LED-RL generated ROS on migration speed, we hypothesized that resveratrol, a potent antioxidant, could prevent the photoinhibitory effects of high fluence LED-RL on fibroblast migration speed.High fluence LED-RL generated ROS were measured by flow cytometry analysis using dihydrorhodamine (DHR. For purposes of comparison, we assessed the effects of ROS generated by hydrogen peroxide (H2O2 on fibroblast migration speed and the ability of resveratrol, a well known antioxidant, to prevent LED-RL and H2O2 generated ROS-associated changes in fibroblast migration speed. To determine whether resveratrol could prevent the high fluence LED-RL ROS-mediated photoinhibition of human skin fibroblast migration, treated cells were incubated with resveratrol at concentrations of 0.0001% and 0.001% for 24 hours, irradiated with high fluences LED-RL of 480, 640, and 800 J/cm2.High fluence LED-RL increases intracellular fibroblast ROS and decreases fibroblast migration speed. LED-RL at 480, 640 and 800 J/cm2 increased ROS levels to 132.8%, 151.0%, and 158.4% relative to matched

  10. Determination of the neutron fluence in the welding of the 'Core shroud' of the BWR reactor core; Determinacion de la fluencia neutronica en las soldaduras del 'core shroud' del nucleo de un reactor BWR

    Lucatero, M.A.; Xolocostli M, J.V.; Gomez T, A.M.; Palacios H, J.C. [ININ, 52750 Ocoyoacac, Estado de mexico (Mexico)]. e-mail: mal@nuclear.inin.mx

    2006-07-01

    With the purpose of defining the inspection frequency, in function of the embrittlement of the materials that compose the welding of the 'Core Shroud' or encircling of the core of a BWR type reactor, is necessary to know the neutron fluence received for this welding. In the work the calculated values of neutron fluence accumulated maxim (E > 1 MeV) during the first 8 operation cycles of the reactor are presented. The calculations were carried out according to the NRC Regulatory Guide 1.190, making use of the DORT code, which solves the transport equation in discreet ordinate in two dimensions (xy, r{theta}, and rz). The results in 3D were obtained applying the Synthesis method according to the guide before mentioned. Results are presented for the horizontal welding H3, H4, and H5, showing the corresponding curves to the fluence accumulated to the cycle 8 and a projection for the cycle 14 is presented. (Author)

  11. Determination of photon fluence spectra from a 60Co therapy unit based on PENELOPE and MCNP simulations

    Photon fluence spectra of the Seibersdorf Labor/BEV Picker 60Co therapy unit were calculated using two generally recognised Monte Carlo codes, PENELOPE-2006 and MCNP5. The complexity of the simulation model was increased in three steps (from a pure source capsule and a simplified model using rotational symmetry to a realistic model of the facility). Photon fluence spectra of both codes generally agree within their statistical standard uncertainties for the case of identical geometry set-up and particle transport parameter settings. Resulting total fluence values were about 0.3% higher for MCNP as compared to PENELOPE. The verification of the simulated photon fluence spectra was based upon depth-dose measurements in water performed with a PTW 31003 ionisation chamber and a thick-walled chamber type CC01. The depth-dose curve calculated with PENELOPE agreed with the curve obtained from measurements within 0.4% across the available depth region in the 30 cm x 30 cm x 30 cm water phantom. The comparison of measured and simulated beam quality indices (TPR20,10) revealed deviations of less than 0.2%.

  12. Pulse-fluence-specified optimal control simulation with applications to molecular orientation and spin-isomer-selective molecular alignment

    We propose an optimal control simulation with specified pulse fluence and amplitude. The simulation is applied to the orientation control of CO molecules to examine the optimal combination of THz and laser pulses, and to discriminate nuclear-spin isomers of 14N2 as spatially anisotropic distributions

  13. Impact of the differential fluence distribution of brachytherapy sources on the spectroscopic dose-rate constant

    Malin, Martha J.; Bartol, Laura J.; DeWerd, Larry A., E-mail: mmalin@wisc.edu, E-mail: ladewerd@wisc.edu [Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin 53705 (United States)

    2015-05-15

    Purpose: To investigate why dose-rate constants for {sup 125}I and {sup 103}Pd seeds computed using the spectroscopic technique, Λ{sub spec}, differ from those computed with standard Monte Carlo (MC) techniques. A potential cause of these discrepancies is the spectroscopic technique’s use of approximations of the true fluence distribution leaving the source, φ{sub full}. In particular, the fluence distribution used in the spectroscopic technique, φ{sub spec}, approximates the spatial, angular, and energy distributions of φ{sub full}. This work quantified the extent to which each of these approximations affects the accuracy of Λ{sub spec}. Additionally, this study investigated how the simplified water-only model used in the spectroscopic technique impacts the accuracy of Λ{sub spec}. Methods: Dose-rate constants as described in the AAPM TG-43U1 report, Λ{sub full}, were computed with MC simulations using the full source geometry for each of 14 different {sup 125}I and 6 different {sup 103}Pd source models. In addition, the spectrum emitted along the perpendicular bisector of each source was simulated in vacuum using the full source model and used to compute Λ{sub spec}. Λ{sub spec} was compared to Λ{sub full} to verify the discrepancy reported by Rodriguez and Rogers. Using MC simulations, a phase space of the fluence leaving the encapsulation of each full source model was created. The spatial and angular distributions of φ{sub full} were extracted from the phase spaces and were qualitatively compared to those used by φ{sub spec}. Additionally, each phase space was modified to reflect one of the approximated distributions (spatial, angular, or energy) used by φ{sub spec}. The dose-rate constant resulting from using approximated distribution i, Λ{sub approx,i}, was computed using the modified phase space and compared to Λ{sub full}. For each source, this process was repeated for each approximation in order to determine which approximations used in

  14. Neutron fluence in a 18 MeV Electron Accelerator for Therapy

    An investigation was made on the theoretical fundamentals for the determination of the neutron fluence in a linear electron accelerator for radiotherapy applications and the limit values of leakage neutron radiation established by guidelines and standards in radiation protection for these type of accelerators. This investigation includes the following parts: a) Exhaustive bibliographical review on the topics mentioned above, in order to combine and to update the necessary basic information to facilitate the understanding of this subject; b) Analysis of the accelerator operation and identification of its main components, specially in the accelerator head; c) Study of different types of targets and its materials for the Bremsstrahlung production which is based on the electron initial energy, the thickness of the target, and its angular distribution and energy, which influences in the neutron generation by means of the photonuclear and electro disintegration reactions; d) Analysis of the neutron yield based on the target type and its thickness, the energy of electrons and photons; e) Analysis of the neutron energy spectra generated in the accelerator head, inside and outside the treatment room; f) Study of the dosimetry fundamentals for neutron and photon mixed fields, the dosimeter selection criteria and standards applied for these applications, specially the Panasonic U D-809 thermoluminescent dosemeter and C R-39 nuclear track dosimeter; g) Theoretical calculation of the neutron yield using a simplified geometric model for the accelerator head with spherical cell, which considers the target, primary collimator, flattener filter, movable collimators and the head shielding as the main components for radiation production. The cases with W and Pb shielding for closed movable collimators and an irradiation field of 20 x 20 cm2 were analyzed and, h) Experimental evaluation of the leakage neutron radiation from the patient and head planes, observing that the accelerator

  15. Probing the Relationship Between Detected Ion Intensity, Laser Fluence, and Beam Profile in Thin Film and Tissue in MALDI MSI

    Steven, Rory T.; Race, Alan M.; Bunch, Josephine

    2016-08-01

    Matrix assisted laser desorption ionization mass spectrometry imaging (MALDI MSI) is increasingly widely used to provide information regarding molecular location within tissue samples. The nature of the photon distribution within the irradiated region, the laser beam profile, and fluence, will significantly affect the form and abundance of the detected ions. Previous studies into these phenomena have focused on circular-core optic fibers or Gaussian beam profiles irradiating dried droplet preparations, where peptides were employed as the analyte of interest. Within this work, we use both round and novel square core optic fibers of 100 and 50 μm diameter to deliver the laser photons to the sample. The laser beam profiles were recorded and analyzed to quantify aspects of the photon distributions and their relation to the spectral data obtained with each optic fiber. Beam profiles with a relatively small number of large beam profile features were found to give rise to the lowest threshold fluence. The detected ion intensity versus fluence relationship was investigated, for the first time, in both thin films of α-cyano-4-hydroxycinnamic acid (CHCA) with phosphatidylcholine (PC) 34:1 lipid standard and in CHCA coated murine tissue sections for both the square and round optic fibers in continuous raster imaging mode. The fluence threshold of ion detection was found to occur at between ~14 and ~64 J/m2 higher in tissue compared with thin film for the same lipid, depending upon the optic fiber employed. The image quality is also observed to depend upon the fluence employed during image acquisition.

  16. Probing the Relationship Between Detected Ion Intensity, Laser Fluence, and Beam Profile in Thin Film and Tissue in MALDI MSI.

    Steven, Rory T; Race, Alan M; Bunch, Josephine

    2016-08-01

    Matrix assisted laser desorption ionization mass spectrometry imaging (MALDI MSI) is increasingly widely used to provide information regarding molecular location within tissue samples. The nature of the photon distribution within the irradiated region, the laser beam profile, and fluence, will significantly affect the form and abundance of the detected ions. Previous studies into these phenomena have focused on circular-core optic fibers or Gaussian beam profiles irradiating dried droplet preparations, where peptides were employed as the analyte of interest. Within this work, we use both round and novel square core optic fibers of 100 and 50 μm diameter to deliver the laser photons to the sample. The laser beam profiles were recorded and analyzed to quantify aspects of the photon distributions and their relation to the spectral data obtained with each optic fiber. Beam profiles with a relatively small number of large beam profile features were found to give rise to the lowest threshold fluence. The detected ion intensity versus fluence relationship was investigated, for the first time, in both thin films of α-cyano-4-hydroxycinnamic acid (CHCA) with phosphatidylcholine (PC) 34:1 lipid standard and in CHCA coated murine tissue sections for both the square and round optic fibers in continuous raster imaging mode. The fluence threshold of ion detection was found to occur at between ~14 and ~64 J/m(2) higher in tissue compared with thin film for the same lipid, depending upon the optic fiber employed. The image quality is also observed to depend upon the fluence employed during image acquisition. Graphical Abstract ᅟ. PMID:27206508

  17. Effects of faceted surface topography on high-fluence sputtering of graphite

    Shulga, V. I.

    2015-11-01

    Effects of ion-induced faceted surface relief on high-fluence sputtering of graphite under 30-keV Ar and 15-keV N ion bombardment have been studied by means of binary-collision computer simulation. Taking into account experimental observations of surface topography, the relief was modeled by an α-dependent ridge-like periodic function (α = the ion incidence angle measured from the normal to macroscopic surface plane). It was shown that for normal incidence the sputter yield S represents a non-monotonic function of the relief aspect ratio and is saturated at x ∼ 100-200 nm (x = the half-period of the relief). The simulations stressed the importance of the relationship between the dimensions of surface roughness and atomic collision cascades and allowed to explain the S(α)-dependences found experimentally. It was shown that a strong (about 2 times) decrease of S at α = 60-80° is due to a shadowing mechanism which is also clearly revealed in the angular distribution of sputtered atoms.

  18. Coincidence of a high-fluence blazar outburst with a PeV-energy neutrino event

    Kadler, M; Mannheim, K; Ojha, R; Müller, C; Schulz, R; Anton, G; Baumgartner, W; Beuchert, T; Buson, S; Carpenter, B; Eberl, T; Edwards, P G; Glawion, D Eisenacher; Elsässer, D; Gehrels, N; Gräfe, C; Hase, H; Horiuchi, S; James, C W; Kappes, A; Katz, U; Kreikenbohm, A; Kreter, M; Kreykenbohm, I; Langejahn, M; Leiter, K; Litzinger, E; Longo, F; Lovell, J E J; McEnery, J; Phillips, C; Plötz, C; Quick, J; Ros, E; Stecker, F W; Steinbring, T; Stevens, J; Thompson, D J; Trüstedt, J; Tzioumis, A K; Wilms, J; Zensus, J A

    2016-01-01

    The discovery of extraterrestrial very-high-energy neutrinos by the IceCube collaboration has launched a quest for the identification of their astrophysical sources. Gamma-ray blazars have been predicted to yield a cumulative neutrino signal exceeding the atmospheric background above energies of 100 TeV, assuming that both the neutrinos and the gamma-ray photons are produced by accelerated protons in relativistic jets. Since the background spectrum falls steeply with increasing energy, the individual events with the clearest signature of being of an extraterrestrial origin are those at PeV energies. Inside the large positional-uncertainty fields of the first two PeV neutrinos detected by IceCube, the integrated emission of the blazar population has a sufficiently high electromagnetic flux to explain the detected IceCube events, but fluences of individual objects are too low to make an unambiguous source association. Here, we report that a major outburst of the blazar PKS B1424-418 occurred in temporal and pos...

  19. Short-wavelength ablation of polymers in the high-fluence regime

    Liberatore, Chiara; Mann, Klaus; Müller, Matthias; Pina, Ladislav; Juha, Libor; Vyšín, Ludek; Rocca, Jorge J.; Endo, Akira; Mocek, Tomas

    2014-05-01

    Short-wavelength ablation of poly(1,4-phenylene ether-ether-sulfone) (PPEES) and poly(methyl methacrylate) (PMMA) was investigated using extreme ultraviolet (XUV) and soft x-ray (SXR) radiation from plasma-based sources. The initial experiment was performed with a 10 Hz desktop capillary-discharge XUV laser lasing at 46.9 nm. The XUV laser beam was focused onto the sample by a spherical mirror coated with a Si/Sc multilayer. The same materials were irradiated with 13.5 nm radiation emitted by plasmas produced by focusing an optical laser beam onto a xenon gas-puff target. A Schwarzschild focusing optics coated with a Mo/Si multilayer was installed at the source to achieve energy densities exceeding 0.1 J cm-2 in the tight focus. The existing experimental system at the Laser Laboratorium Göttingen was upgraded by implementing a 1.2 J driving laser. An increase of the SXR fluence was secured by improving the alignment technique.

  20. Short-wavelength ablation of polymers in the high-fluence regime

    Short-wavelength ablation of poly(1,4-phenylene ether-ether-sulfone) (PPEES) and poly(methyl methacrylate) (PMMA) was investigated using extreme ultraviolet (XUV) and soft x-ray (SXR) radiation from plasma-based sources. The initial experiment was performed with a 10 Hz desktop capillary-discharge XUV laser lasing at 46.9 nm. The XUV laser beam was focused onto the sample by a spherical mirror coated with a Si/Sc multilayer. The same materials were irradiated with 13.5 nm radiation emitted by plasmas produced by focusing an optical laser beam onto a xenon gas-puff target. A Schwarzschild focusing optics coated with a Mo/Si multilayer was installed at the source to achieve energy densities exceeding 0.1 J cm−2 in the tight focus. The existing experimental system at the Laser Laboratorium Göttingen was upgraded by implementing a 1.2 J driving laser. An increase of the SXR fluence was secured by improving the alignment technique. (paper)

  1. Absorbed Dose in Ion Beams: Comparison of Ionization and Fluence-based Measurements

    Osinga, Julia-Maria; Bartz, James A; Akselrod, Mark S; Jäkel, Oliver; Greilich, Steffen

    2013-01-01

    We present a direct comparison measurement of fluorescent nuclear track detectors (FNTDs) and a thimble ionization chamber. Irradiations were performed at the Heidelberg Ion-Beam Therapy Center (HIT) using monoenergetic protons (142.66 MeV, 3x10^6 1/cm2) and carbon ions (270.55 MeV/u, 3x10^6 1/cm2) in the entrance channel of the ion beam. We found that absorbed dose to water values as determined by fluence measurements using FNTDs are in case of protons in good agreement (2.2 %) with ionization chamber measurements when including slower protons and Helium secondaries by an effective stopping power. For carbon, however, we found a discrepancy of 4.6 %. This deviation is significant considering both the uncertainties for ionization chambers as given in the TRS 398 and from experimental design (e.g. inhomogeneous irradiation, machine stability, beam direction). Additionally, the abundance of secondary protons expected from Monte-Carlo transport simulation was not seen.

  2. Verification for a GEOSHIELD application to the SMART vessel fluence by a Monte Carlo simulation

    In general the two dimensional discrete ordinates transport code DORT has been used for an evaluation of neutron and gamma fluxes during a shielding design of nuclear reactors. It is very complicated and it takes too much time for shielding designers to prepare input data such as a geometrical modeling and a source distribution and to process an output of the results from the shielding analysis. The GEOSHIELD code was developed to save the time spent preparing a geometrical model and an output processing. The GEOSHIELD code is composed of a module for a geometrical modeling by using a combinatorial geometry, a module for a fixed source redistribution, a module for a DORT processing, and a module for a graphical processing of the output activities. The evaluation of an irradiation of a fast neutron which has an energy of higher than 1.0 MeV is very important to verify the integrity of an internal structure including a pressure vessel. The GEOSHIELD code was applied to evaluate a fast neutron fluence distribution on the internal structures inside the reactor pressure vessel of the SMART reactor and the MCNP was used for verification of the result from the GEOSHIELD calculation. Result of the GEOSHIELD and MCNP showed good agreement each other. (author)

  3. Impact of fluence-rate related effects on the sputtering of silicon at elevated target temperatures

    In this work we show how ion-beam-induced epitaxial recrystallization plays a role in focused ion-beam (FIB) sputtering of silicon at elevated temperatures. The sputtering process is the key to all high-precision machining of microstructures and nanostructures by FIBs. A fluence-rate effect observed for the sputtering of silicon at elevated temperatures arises from competition between stabilizing interactions between populations of defects produced by consecutive ion impingement (damage buildup) and dynamic self-annealing. By high-resolution transmission electron microscopy analysis we show that the damage, produced by exposure of silicon to a 50 kV focused gallium (Ga) ion beam at elevated target temperatures, departs quite substantially from the expected damage based on the distribution of energy within the substrate due to nuclear stopping. An amorphous layer observed at room temperature is completely absent at higher temperatures. In contrast to FIB exposure at room temperature the implanted layers contain only point defects complexes and dislocations, thus suggesting that defect annealing takes place but it is incomplete. Correlating FIB sputtering experiments and high-resolution transmission electron microscopy, we discuss the lower sputtering yield at elevated target temperatures as the result of a higher surface binding energy of crystalline Si in comparison to amorphous silicon

  4. Energetic Fe particle fluence measured in 2002-2004 on the ISS orbit

    Nymmik, Rikho; Baranov, Dmitrii; Dergachev, Valentin; Panasyuk, Mikhail; Gagarin, Yurii

    PLATAN-M chamber consisting of solid state track detectors was exposed at the outer surface of the ISS during 2002-2004. Fluence of Fe particles (SEPs and GCRs) was measured in the 30-150 MeV/nucleon energy range. Results of the PLATAN-M experiment were compared with the data obtained by the SIS and CRIS instruments (ACE spacecraft). Energy resolution of the PLATAN-M experiment was 3 times better with statistical errors being 2 times lower as compared with the SIS instrument. Spectra measured outside the magnetosphere of the Earth were transformed to the ISS orbit using the model of charged particle penetration to the near-Earth orbit. General coincidence of the results obtained at the two space stations can be seen. Yet some of the SIS energy channels display outliers distant for 6 standard errors from the PLATAN-M spectrum. Comparison of data obtained at the orbital station with measurements carried out in the interplanetary space evidences the reliability of the model describing the transformation of spectra during charged particle penetration inside the magnetosphere. Thus, a broad range of possibilities arises for the study of energetic particles combining the data measured by different instruments both outside and inside the magnetosphere of the Earth.

  5. Response to heating of dislocation structures in zircaloy-2 irradiated to high neutron fluences

    Zirconium alloys have good neutron economy and corrosion resistance in high temperature water and this has led to extensive usage of these alloys in CANDU reactors. However, during neutron irradiation, dimensional changes occur in zirconium components due to the rearrangement of atoms knocked from their lattice sites by fast neutrons. This irradiation growth may limit the lifetime of some reactor components and an understanding of the variables that control the process is of commercial importance. In the current work, the temperature response of the irradiation-induced microstructure was studied by heating foils in the TEM and by annealing bulk specimens. Thin foils of Zircaloy-2 irradiated at 570 K to a fluence of 8 x 1025 n/m2, E > 1.0 MeV, were examined in the heating stage of a Philips EM300 microscope. Surface hydrides were seen to dissolve with increasing temperature. The line defects were stable at temperatures up to 850 K, removing any possibility of their being some form of hydride precipitate. In bulk specimens of the same material heated in vacuum to 773 K for 1 hour, c component dislocations were still evident. Small damage clusters, noted in the as-irradiated foil, have now formed visible loops and line dislocations. Interactions between the c and a type dislocations are difficult to observe due to the high damage density. The implications to irradiation growth of irradiation-induced dislocation structures with c component Burgers vectors will be discussed

  6. High-fluence neutron irradiation of superconducting NbN films

    A variety of sputtered NbN films have been irradiated with reactor neutrons at ambient temperature up to a total fluence of 1023 m-2 (E > 0.1 MeV). Only small decreases of T/sub c/ (4--7%) and moderate increases of /rho//sub n/ (/approximately/25%) are observed. Both of these quantities are difficult to interpret because of the granular nature of the films. The critical current densities have been determined in most cases for magnetic fields up to 20 T. While some degradation (/approximately/30%) of j/sub c/ occurs in the intermediate field range (6--15 T), the high field data show no change of j/sub c/ or even small increases due to the radiation-induced increase of H/sub c2/ and the occurrence of peak effects near H/sub c2/. The present experiments demonstrate unambiguously that NbN is an extremely radiation-hard high-field superconductor. 17 refs., 9 figs., 2 tabs

  7. Effect of neutron energy and fluence on deuterium retention behaviour in neutron irradiated tungsten

    Fujita, Hiroe; Yuyama, Kenta; Li, Xiaochun; Hatano, Yuji; Toyama, Takeshi; Ohta, Masayuki; Ochiai, Kentaro; Yoshida, Naoaki; Chikada, Takumi; Oya, Yasuhisa

    2016-02-01

    Deuterium (D) retention behaviours for 14 MeV neutron irradiated tungsten (W) and fission neutron irradiated W were evaluated by thermal desorption spectroscopy (TDS) to elucidate the correlation between D retention and defect formation by different energy distributions of neutrons in W at the initial stage of fusion reactor operation. These results were compared with that for Fe2+ irradiated W with various damage concentrations. Although dense vacancies and voids within the shallow region near the surface were introduced by Fe2+ irradiation, single vacancies with low concentration were distributed throughout the sample for 14 MeV neutron irradiated W. Only the dislocation loops were introduced by fission neutron irradiation at low neutron fluence. The desorption peak of D for fission neutron irradiated W was concentrated at low temperature region less than 550 K, but that for 14 MeV neutron irradiated W was extended toward the higher temperature side due to D trapping by vacancies. It can be said that the neutron energy distribution could have a large impact on irradiation defect formation and the D retention behaviour.

  8. Anthocyanin Accumulation Mediated by Blue Light and Cytokinin in Arabidopsis Seedlings

    2006-01-01

    It has been reported that pigmentation in plants is stimulated by light and cytokinin (CTK); however, the signaling pathways and the relationship between light and CTK involved in the regulation of anthocyanin accumulation remain to be elucidated. We investigated (i) the role of blue light (BL) and CTK in anthocyanin accumulation; and (ii) the relationship between BL and CTK in wild type (WT) and hy4 mutants of Arabidopsis thaliana. Two-d-old seedlings grown on medium with or without kinetin (KT) or zeatin (ZT) in darkness were irradiated using BL at different fluence rates for 3 d before the anthocyanin content was determined using a spectrophotometric method. Anthocyanin accumulation was strongly induced by BL in WT seedlings but not in hy4 seedlings, which demonstrated that CRY1 is the main photoreceptor for BL. Both KT and ZT enhanced the response of the WT seedlings to BL in a dose-dependent manner, whereas they were not sufficient to promote anthocyanin accumulation in darkness. In addition, data from experiments using the hy4 mutant showed that the CTK effect of BL was also CRY1-dependent. The results from experiments with three different treatment programs showed that the relationship between BL and KT in anthocyanin accumulation of Arabidopsis seedlings seems neither multiplicative nor additive coaction, but rather interaction. BL is necessary for anthocyanin accumulation, and KT might be involved in the BL signaling pathway.

  9. Research methods for evaluation absorbing and accumulating nuclides of plant

    This paper reviewed the recent studies on plants absorption and accumulation of nuclides and divided the studies to several aspects such as monitoring, mechanism restoration, and stressing based on their purpose. The paper also summarized the methods for selection and treatment of nuclides, plants preparation, nuclides test and evaluation. (authors)

  10. Evidence accumulation for spatial reasoning

    Matsuyama, T.; Hwang, V. S. S.; Davis, L. S.

    1984-01-01

    The evidence accumulation proces of an image understanding system is described enabling the system to perform top-down(goal-oriented) picture processing as well as bottom-up verification of consistent spatial relations among objects.

  11. Oligopoly banking and capital accumulation

    Nicola Cetorelli; Pietro F. Peretto

    2000-01-01

    We develop a dynamic general equilibrium model of capital accumulation where credit is intermediated by banks operating in a Cournot oligopoly. The number of banks affects capital accumulation through two channels. First, it affects the quantity of credit available to entrepreneurs. Second, it affects banks' decisions to collect costly information about entrepreneurs, and thus determines the efficiency of the credit market. We show that under plausible conditions, the market structure that ma...

  12. Cystathionine accumulation in Saccharomyces cerevisiae.

    Ono, B; Suruga, T; Yamamoto, M.; Yamamoto, S.; Murata, K; Kimura, A; Shinoda, S; Ohmori, S.

    1984-01-01

    A cysteine-dependent strain of Saccharomyces cerevisiae and its prototrophic revertants accumulated cystathionine in cells. The cystathionine accumulation was caused by a single mutation having a high incidence of gene conversion. The mutation was designated cys3 and was shown to cause loss of gamma-cystathionase activity. Cysteine dependence of the initial strain was determined by two linked and interacting mutations, cys3 and cys1 . Since cys1 mutations cause a loss of serine acetyltransfer...

  13. Atom probe tomography characterizations of high nickel, low copper surveillance RPV welds irradiated to high fluences

    The Ringhals Units 3 and 4 reactors in Sweden are pressurized water reactors (PWRs). The reactor pressure vessels (RPVs) for both reactors were fabricated with ring forgings of SA 508 class 2 steel. Surveillance blocks for both units were fabricated using the same weld wire heat, welding procedures, and base metals used for the RPVs. The primary interest in these weld metals is because they have very high nickel contents, with 1.58 and 1.66 wt.% for Unit 3 and Unit 4, respectively. The nickel content in Unit 4 is the highest reported nickel content for any Westinghouse PWR. Although both welds contain less than 0.10 wt.% copper, the weld metals have exhibited high irradiation-induced Charpy 41-J transition temperature shifts in surveillance testing. The Charpy impack 41-J shifts and the corresponding fluences are 192 deg C at 5.0 x 1023 n/m2 (>1 MeV) for Unit 3 and 162 deg C at 6.0 x 1023 n/m2 (1 MeV) for unit 4. These relatively low-copper, high-nickel, radiation-sensitive welds relate to the issue of so-called late-blooming nickel-manganese-silicon phases. Atom probe tomography measurements have revealed ∼2 nm-diameter irradiation-induced precipitates containing manganese, nickel, and silicon, with phosphorus evident in some of the precipitates. However, only a relatively few number of copper atoms are contained within the precipitates. The larger increase in the transition temperature shift in the higher copper weld metal from the Ringhals R3 Unit is associated with copper-enriched regions within the manganese-nickel-silicon-enriched precipitates rather than changes in their size or number density.

  14. Atom probe tomography characterizations of high nickel, low copper surveillance RPV welds irradiated to high fluences

    The Ringhals Units 3 and 4 reactors in Sweden are pressurized water reactors (PWRs) designed and supplied by Westinghouse Electric Company, with commercial operation in 1981 and 1983, respectively. The reactor pressure vessels (RPVs) for both reactors were fabricated with ring forgings of SA 508 class 2 steel. Surveillance blocks for both units were fabricated using the same weld wire heat, welding procedures, and base metals used for the RPVs. The primary interest in these weld metals is because they have very high nickel contents, with 1.58 and 1.66 wt.% for Unit 3 and Unit 4, respectively. The nickel content in Unit 4 is the highest reported nickel content for any Westinghouse PWR. Although both welds contain less than 0.10 wt.% copper, the weld metals have exhibited high irradiation-induced Charpy 41-J transition temperature shifts in surveillance testing. The Charpy impact 41-J shifts and corresponding fluences are 192 °C at 5.0 × 1023 n/m2 (>1 MeV) for Unit 3 and 162 °C at 6.0 × 1023 n/m2 (>1 MeV) for Unit 4. These relatively low-copper, high-nickel, radiation-sensitive welds relate to the issue of so-called late-blooming nickel–manganese–silicon phases. Atom probe tomography measurements have revealed ∼2 nm-diameter irradiation-induced precipitates containing manganese, nickel, and silicon, with phosphorus evident in some of the precipitates. However, only a relatively few number of copper atoms are contained within the precipitates. The larger increase in the transition temperature shift in the higher copper weld metal from the Ringhals R3 Unit is associated with copper-enriched regions within the manganese–nickel–silicon-enriched precipitates rather than changes in their size or number density

  15. Persistent oxidative stress in human neural stem cells exposed to low fluences of charged particles

    Janet E. Baulch

    2015-08-01

    Full Text Available Exposure to the space radiation environment poses risks for a range of deleterious health effects due to the unique types of radiation encountered. Galactic cosmic rays are comprised of a spectrum of highly energetic nuclei that deposit densely ionizing tracks of damage along the particle trajectory. These tracks are distinct from those generated by the more sparsely ionizing terrestrial radiations, and define the geometric distribution of the complex cellular damage that results when charged particles traverse the tissues of the body. The exquisite radiosensitivity of multipotent neural stem and progenitor cells found within the neurogenic regions of the brain predispose the central nervous system to elevated risks for radiation induced sequelae. Here we show that human neural stem cells (hNSC exposed to different charged particles at space relevant fluences exhibit significant and persistent oxidative stress. Radiation induced oxidative stress was found to be most dependent on total dose rather than on the linear energy transfer of the incident particle. The use of redox sensitive fluorogenic dyes possessing relative specificity for hydroxyl radicals, peroxynitrite, nitric oxide (NO and mitochondrial superoxide confirmed that most irradiation paradigms elevated reactive oxygen and nitrogen species (ROS and RNS, respectively in hNSC over a 1 week interval following exposure. Nitric oxide synthase (NOS was not the major source of elevated nitric oxides, as the use of NOS inhibitors had little effect on NO dependent fluorescence. Our data provide extensive evidence for the capability of low doses of charged particles to elicit marked changes in the metabolic profile of irradiated hNSC. Radiation induced changes in redox state may render the brain more susceptible to the development of neurocognitive deficits that could affect an astronaut’s ability to perform complex tasks during extended missions in deep space.

  16. Fluence reduction of nuclear reactor pressure vessels by fuel-management strategies

    A study is presented which evaluates three different fuel-management schemes for reducing fast-neutron fluence on PWR (pressurized water reactor) pressure vessels. The schemes consist of a low leakage loading pattern (L-3) and a very low leakage loading pattern (VLL) and a very low leakage loading pattern with stainless-steel dummy fuel assemblies on the core edge (VLL + SS). The loading patterns require power derating to offset the maximum allowable pin-power peaking factor in the core. A 2-D nodal computer code, CYCLOPS, was used to calculate the physics, burnup and economics of the three alternative policies. For each fuel-loading policy, three average batch enrichments were used: 3.50, 3.73 and 4.00% 235U. The 450 MW(e) Westinghouse PWR, San Onofre Unit No. 1 (SONGS-1) was selected as a representative unit for this study. The VLL fuel management policy with 4.00% 235U enrichment was found to give the most favorable advantages. The pressure vessel lifetime is extended by 6.8 yr to 34.8 yr. The total electrical output of 8.272 x 1010 kWh from Cycle 8 to end of life (EOL) represents a 5.93% increase over the present policy. The least favorable policy increases the vessel life by only 0.88 yr, but because of the required power derating the total electrical output to EOL is reduced to 6.31 x 1010 kWh, a decrease of 19.17% from the present policy output of 7.809 x 1010 kWh from Cycle 8 to EOL. An economic study, with realistic current unit costs, shows that the levelized cost of electricity at the bus bar would increase by approx. 3% for the most favorable policy over the present policy cost. This increase is mostly due to the power derating from 1347 to 1206 MW(th). (author)

  17. Coincidence of a high-fluence blazar outburst with a PeV-energy neutrino event

    Kadler, M.; Krauß, F.; Mannheim, K.; Ojha, R.; Müller, C.; Schulz, R.; Anton, G.; Baumgartner, W.; Beuchert, T.; Buson, S.; Carpenter, B.; Eberl, T.; Edwards, P. G.; Eisenacher Glawion, D.; Elsässer, D.; Gehrels, N.; Gräfe, C.; Gulyaev, S.; Hase, H.; Horiuchi, S.; James, C. W.; Kappes, A.; Kappes, A.; Katz, U.; Kreikenbohm, A.; Kreter, M.; Kreykenbohm, I.; Langejahn, M.; Leiter, K.; Litzinger, E.; Longo, F.; Lovell, J. E. J.; McEnery, J.; Natusch, T.; Phillips, C.; Plötz, C.; Quick, J.; Ros, E.; Stecker, F. W.; Steinbring, T.; Stevens, J.; Thompson, D. J.; Trüstedt, J.; Tzioumis, A. K.; Weston, S.; Wilms, J.; Zensus, J. A.

    2016-08-01

    The astrophysical sources of the extraterrestrial, very high-energy neutrinos detected by the IceCube collaboration remain to be identified. Gamma-ray (γ-ray) blazars have been predicted to yield a cumulative neutrino signal exceeding the atmospheric background above energies of 100 TeV, assuming that both the neutrinos and the γ-ray photons are produced by accelerated protons in relativistic jets. As the background spectrum falls steeply with increasing energy, the individual events with the clearest signature of being of extraterrestrial origin are those at petaelectronvolt energies. Inside the large positional-uncertainty fields of the first two petaelectronvolt neutrinos detected by IceCube, the integrated emission of the blazar population has a sufficiently high electromagnetic flux to explain the detected IceCube events, but fluences of individual objects are too low to make an unambiguous source association. Here, we report that a major outburst of the blazar PKS B1424-418 occurred in temporal and positional coincidence with a third petaelectronvolt-energy neutrino event (HESE-35) detected by IceCube. On the basis of an analysis of the full sample of γ-ray blazars in the HESE-35 field, we show that the long-term average γ-ray emission of blazars as a class is in agreement with both the measured all-sky flux of petaelectronvolt neutrinos and the spectral slope of the IceCube signal. The outburst of PKS B1424-418 provides an energy output high enough to explain the observed petaelectronvolt event, suggestive of a direct physical association.

  18. Induction of Chromosomal Aberrations at Fluences of Less Than One HZE Particle per Cell Nucleus

    Hada, Megumi; Chappell, Lori J.; Wang, Minli; George, Kerry A.; Cucinotta, Francis A.

    2014-01-01

    The assumption of a linear dose response used to describe the biological effects of high LET radiation is fundamental in radiation protection methodologies. We investigated the dose response for chromosomal aberrations for exposures corresponding to less than one particle traversal per cell nucleus by high energy and charge (HZE) nuclei. Human fibroblast and lymphocyte cells where irradiated with several low doses of <0.1 Gy, and several higher doses of up to 1 Gy with O (77 keV/ (long-s)m), Si (99 keV/ (long-s)m), Fe (175 keV/ (long-s)m), Fe (195 keV/ (long-s)m) or Fe (240 keV/ (long-s)m) particles. Chromosomal aberrations at first mitosis were scored using fluorescence in situ hybridization (FISH) with chromosome specific paints for chromosomes 1, 2 and 4 and DAPI staining of background chromosomes. Non-linear regression models were used to evaluate possible linear and non-linear dose response models based on these data. Dose responses for simple exchanges for human fibroblast irradiated under confluent culture conditions were best fit by non-linear models motivated by a non-targeted effect (NTE). Best fits for the dose response data for human lymphocytes irradiated in blood tubes were a NTE model for O and a linear response model fit best for Si and Fe particles. Additional evidence for NTE were found in low dose experiments measuring gamma-H2AX foci, a marker of double strand breaks (DSB), and split-dose experiments with human fibroblasts. Our results suggest that simple exchanges in normal human fibroblasts have an important NTE contribution at low particle fluence. The current and prior experimental studies provide important evidence against the linear dose response assumption used in radiation protection for HZE particles and other high LET radiation at the relevant range of low doses.

  19. Validation of Three-Dimensional Synthesis RPV Neutron Fluence Calculations Using VVER-1000 Ex-Vessel Reference Dosimetry Results

    According to Russian federal norms and the safety guide of the nuclear regulatory body of Russia, the maximum fast neutron fluence above 0.5 MeV at critical positions of the reactor pressure vessel (RPV) of VVER-type reactors is used for prediction of the RPV lifetime. For the computation of neutron fluences in the RPV near the reactor core midplane level, the three-dimensional (3-D) synthesis method based on two- and one-dimensional SN calculations may be acceptable but needs validation. The present validation analysis was carried out on the basis of neutron transport calculations for a VVER-1000 model by means of the well-known codes DORT (R, Θ- and R, Z geometry) and ANISN (R geometry) using the multigroup library BUGLE-96. The 3-D spatial neutron source distribution, including pin-to-pin power variations and the complex baffle construction, were modeled in detail

  20. Development of multi-channel amplifier-discriminator based on measurement system of neutron fluence rate relative distribution in reactor

    For the measurement of neutron fluence rate in reactor and reliable assurance of γ count measurement of activated 55Mn-58Ni alloy irradiated foils in reactor, 9-channel amplifier-discriminator was developed. The main technical parameter test and application test show that the gain of each channel amplifier-discriminator is continuously adjustable from 1 to 21, the threshold of each discriminator circuit is continuously adjustable, the maximum count rate and sensitivity of discriminator circuit are high, and the system has stable property and excellent anti-interference. In conclusion, relevant technical parameters can guarantee the real-time and long-term stable measurement of neutron fluence rate relative distribution in reactor, with the technical parameters that gain stability of amplifier is less than 1%, the minimum input pulse width of discriminator circuit is greater than 0.1 μs, and the maximum count rate of discriminator is less than 4×106 s-1. (authors)

  1. Neutron fluences of the D-D fusion reaction at 1016 W/cm2 laser-target interactions

    In last decade many studies have been carried on deuterium-deuterium nuclear reaction induced in laser-target interactions. The relationships between neutron yields and reaction mechanisms and laser-target patterns need to be further clarified. In this contribution we investigate on fusion yields by changing the target thickness and composition and the laser energy and focal position. The experiment has been performed at PALS Laboratory in Prague. Ion yields have been measured by a Thomson spectrometer and by SiC detectors placed at suitable distances in TOF configuration. Neutron fluences have been evaluated by neutron bubble dosimeters and CR39 track detectors. Results about neutron fluences and fusion process are presented and discussed.

  2. Atmospheric ionization by high-fluence, hard spectrum solar proton events and their probable appearance in the ice core archive

    Melott, Adrian L; Laird, Claude M; Neuenswander, Ben; Atri, Dimitra

    2016-01-01

    Solar energetic particles ionize the atmosphere, leading to production of nitrogen oxides. It has been suggested that some such events are visible as layers of nitrate in ice cores, yielding archives of energetic, high fluence solar proton events (SPEs). There has been controversy, due to slowness of transport for these species down from the upper stratosphere; past numerical simulations based on an analytic calculation have shown very little ionization below the mid stratosphere. These simulations suffer from deficiencies: they consider only soft SPEs and narrow energy ranges; spectral fits are poorly chosen; with few exceptions secondary particles in air showers are ignored. Using improved simulations that follow development of the proton-induced air shower, we find consistency with recent experiments showing substantial excess ionization down to 5 km. We compute nitrate available from the 23 February 1956 SPE, which had a high fluence, hard spectrum, and well-resolved associated nitrate peak in a Greenland...

  3. Ion-fluence dependencies of surface modification and sterilization of PET film in the plasma ion-implantation process

    We are developing new technologies of polymer surface modification as well as low temperature sterilization by plasma based ion implantation. Microwave plasma source equipped with plasma based ion implantation is used. Until now, both the surface modification of PET and the sterilization of Bacillus subtilis have been verified. However, it has been difficult to get quantitative dependencies of the surface modification and the sterilization on the ion fluence, since it has been difficult to measure the exact value of the ion fluence during the plasma ion implantation process. In this study we tried to measure the exact value by making a new Faraday cup. Consequently, it was proved that the sterilization would finish in the midst of modification process, sufficiently before the surface modification would be completed. (author)

  4. Divergence of Cs-137 sources fluence used in brachytherapy; Divergencia da fluencia de fontes de Cs-137 usadas em braquiterapia

    Vianello, E.A.; Almeida, C.E. de [Laboratorio de Ciencias Radiologicas- LCR-DBB (UERJ). R. Sao Francisco Xavier, 524- Pav. HLC, sala 136 terreo- CEP 20.550- 013. Rio de Janeiro (Brazil)

    1998-12-31

    In this work the experimental determination of correction factor for fluence divergence (kln) of linear Cs-137 sources CDCS J4, with Farmer ionization chamber model 2571 in a central and perpendicular plan to source axis, for distances range from 1 to 7 cm., has been presented. The experimental results were compared to calculating by Kondo and Randolph (1960) isotropic theory and Bielajew (1990) anisotropic theory. (Author)

  5. Hypopigmentation Induced by Frequent Low-Fluence, Large-Spot-Size QS Nd:YAG Laser Treatments

    Wong, Yisheng; Lee, Siong See Joyce; Goh, Chee Leok

    2015-01-01

    The Q-switched 1064-nm neodymium-doped yttrium aluminum garnet (QS 1064-nm Nd:YAG) laser is increasingly used for nonablative skin rejuvenation or "laser toning" for melasma. Multiple and frequent low-fluence, large-spot-size treatments are used to achieve laser toning, and these treatments are associated with the development of macular hypopigmentation as a complication. We present a case series of three patients who developed guttate hypomelanotic macules on the face after receiving laser t...

  6. Width of Nucleation Region of Si Nanocrystal Grains Prepared by Pulsed Laser Ablation with Different Laser Fluence

    Zechao Deng; Xuexia Pang; Xuecheng Ding; Lizhi Chu; Yinglong Wang

    2015-01-01

    Si nanocrystal grains were prepared by pulsed laser ablation with different laser fluence in Ar gas of 10 Pa at room temperature. The as-formed grains in the space deposited on the substrates and distributed in a certain range apart from target. According to the depositing position and radius of grains, the nucleation locations of grains in the space were roughly calculated. The results indicated that the width of nucleation region broadened with increasing of ion densities diagnosed by Langm...

  7. Comparison of prophylactic higher fluence corneal cross-linking to control, in myopic LASIK, one year results

    Kanellopoulos, John

    2014-01-01

    Anastasios John Kanellopoulos,1,2 George Asimellis,1 Costas Karabatsas1 1LaserVision.gr Clinical and Research Eye Institute, Athens, Greece; 2New York University Medical School, New York, NY, USA Purpose: To compare 1-year results: safety, efficacy, refractive and keratometric stability, of femtosecond myopic laser-assisted in situ keratomileusis (LASIK) with and without concurrent prophylactic high-fluence cross-linking (CXL) (LASIK-CXL).Methods: We studied a total of 155&nbs...

  8. Comparison of prophylactic higher fluence corneal cross-linking to control, in myopic LASIK, one year results

    Kanellopoulos AJ; Asimellis G; Karabatsas C

    2014-01-01

    Anastasios John Kanellopoulos,1,2 George Asimellis,1 Costas Karabatsas1 1LaserVision.gr Clinical and Research Eye Institute, Athens, Greece; 2New York University Medical School, New York, NY, USA Purpose: To compare 1-year results: safety, efficacy, refractive and keratometric stability, of femtosecond myopic laser-assisted in situ keratomileusis (LASIK) with and without concurrent prophylactic high-fluence cross-linking (CXL) (LASIK-CXL).Methods: We studied a total of 155 consec...

  9. Combination therapy of low-fluence photodynamic therapy and intravitreal ranibizumab for choroidal neovascular membrane in choroidal osteoma

    Morris, Rodney J; Prabhu, Varsha V; Parag K Shah; Narendran, V.

    2011-01-01

    Choroidal osteoma is an unusual form of intraocular calcification seen in otherwise healthy eyes. It is a benign idiopathic osseous tumor of the choroid, typically seen in young females. Choroidal neovascular membrane (CNVM) is a complication seen in one-third of these patients and carries a poor visual outcome. We report a case of a 25-year-old hyperthyroid female with choroidal osteoma and subfoveal CNVM in her left eye which was successfully treated using low-fluence photodynamic therapy (...

  10. Evaluation of the Analytical Anisotropic Algorithm (AAA) in dose calculation for fields with non-uniform fluences considering heterogeneity correction

    The purpose of this study is to evaluate the calculation of dose distribution AAA (Varian Medical Systems) for fields with non-uniform fluences considering heterogeneity correction. Five different phantoms were used with different density materials. These phantoms were scanned in the CT BrightSpeed (©GE Healthcare) upon the array of detectors MAPCHECK2 TM (Sun Nuclear Corporation) and irradiated in a linear accelerator 600 CD (Varian Medical Systems) 6MV and rate dose 400MU/min with isocentric setup. The fluences used were exported from IMRT plans, calculated by ECLIPSE™ planning system (Varian Medical Systems), and a 10x10 cm2 field to assess the heterogeneity correction for uniform fluence. The measured dose distribution was compared to the calculated by Gamma analysis with approval criteria of 3% / 3 mm and 10% threshold. The evaluation was performed using the software SNCPatient (Sun Nuclear Corporation) and considering absolute dose normalized at maximum. The phantoms best performers were those with low density materials, with an average of 99.2% approval. Already phantoms with plates of higher density material presented various fluences below 95% of the points approved. The average value reached 94.3%. It was observed a dependency between fluency and approved percentage points, whereas for the same fluency, 100% of the points have been approved in all phantoms. The approval criteria for IMRT plans recommended in most centers is 3% / 3mm with at least 95% of points approved, it can be concluded that, under these conditions, the IMRT plans with heterogeneity correction can be performed , however the quality control must be careful because the difficulty of the system to accurately predict the dose distribution in certain situations. (author)

  11. Effect of ultrasound transducer face reflectivity on the light fluence inside a turbid medium in photoacoustic imaging

    Tavakoli, Behnoosh; Kumavor, Patrick D.; Aguirre, Andres; Zhu, Quing

    2010-01-01

    Many endoscopic, intravascular, and transvaginal applications require light to be delivered through optical fibers in a reflection mode. For photoacoustic imaging in reflection geometry, the front-face reflectivity of the ultrasound transducer face imposes a boundary condition that affects the light fluence and its distribution inside a turbid medium. Understanding and characterizing this boundary condition is critical for maximizing tissue illumination and therefore the signal-to-noise ratio...

  12. A unified framework for 3D radiation therapy and IMRT planning: plan optimization in the beamlet domain by constraining or regularizing the fluence map variations

    The purpose of this work is to demonstrate that physical constraints on fluence gradients in 3D radiation therapy (RT) planning can be incorporated into beamlet optimization explicitly by direct constraint on the spatial variation of the fluence maps or implicitly by using total-variation regularization (TVR). The former method forces the fluence to vary in accordance with the known form of a wedged field and latter encourages the fluence to take the known form of the wedged field by requiring the derivatives of the fluence maps to be piece-wise constant. The performances of the proposed methods are evaluated by using a brain cancer case and a head and neck case. It is found that both approaches are capable of providing clinically sensible 3D RT solutions with monotonically varying fluence maps. For currently available 3D RT delivery schemes based on the use of customized physical or dynamic wedges, constrained optimization seems to be more useful because the optimized fields are directly deliverable. Working in the beamlet domain provides a natural way to model the spatial variation of the beam fluence. The proposed methods take advantage of the fact that 3D RT is a special form of intensity-modulated radiation therapy (IMRT) and finds the optimal plan by searching for fields with a certain type of spatial variation. The approach provides a unified framework for 3D CRT and IMRT plan optimization. (note)

  13. An investigation into the effects of high laser fluence on hydroxyapatite/calcium phosphate films deposited by pulsed laser deposition

    Pulsed laser deposited mixed hydroxyapatite (HA)/calcium phosphate thin films were prepared at room temperature using KrF laser source with different laser fluence varying between 2.4 J/cm2 and 29.2 J/cm2. Samples deposited at 2.4 J/cm2 were partially amorphous and had rough surfaces with a lot of droplets while higher laser fluences showed higher level of crytallinity and lower roughness of surfaces of obtained samples. Higher laser fluences also decreased ratio Ca/P of as-deposited samples. X-ray photoelectron spectroscopy (XPS) revealed traces of carbonate groups in obtained samples, which were removed after thermal annealing. The decomposition of HA into TCP was observed to start at about 400 deg. C. The formation of new crystalline phase of HA was found after annealing as well. The cracks observed on surface of sample deposited at 29.2 J/cm2 after annealing indicated that the HA/ calcium phosphate films deposited at higher laser energy densities were probably more densed.

  14. Dispersive hole growth kinetics and fluence broadening of the zero-phonon hole of impurities in amorphous hosts

    A detailed treatment of the relationship between the dispersive growth kinetics of the zero-phonon hole (ZPH) of an impurity molecule in an amorphous host and burn fluence broadening of the ZPH is presented. Focus is on non-photochemical hole burning (NPHB). The equation used for simulations accounts for dispersion due to a distribution of tunneling parameters (λ-distribution), the angle between the laser polarization and the transition dipole (α-distribution), and off-resonant absorption of the zero-phonon line (ω-distribution). Two cases are considered: burned laser linewidth narrow relative to the homogeneous width of the zero-phonon line; and the reverse situation. Results are presented for two model systems whose parameter values are similar to those of aluminum phthalocyanine tetrasulphonate (APT) in hyperquenched glassy water and in hyperquenched glassy ethanol. For comparison, results are presented for the case where the hole growth kinetics are non-dispersive (single-exponential). It is found that at the early stage of burning fluence broadening is considerably more severe for a dispersive system than for a non-dispersive system. A straightforward explanation for this is given. The results are compared with those of earlier works on dispersive hole growth kinetics and fluence broadening. The results reveal the types of experiment needed to understand the aforementioned relationship, a requirement for determination of the homogeneous width of the ZPH that reflects the dynamics of the system

  15. Role of laser fluence in protein synthesis of cultured DRG neurons following low-level laser irradiation

    Zheng, Liqin; Qiu, Caimin; Wang, Yuhua; Zeng, Yixiu; Yang, Hongqin; Zhang, Yanding; Xie, Shusen

    2014-11-01

    Low-level lasers have been used to relieve pain in clinical for many years. But the mechanism is not fully clear. In animal models, nitric oxide (NO) has been reported involving in the transmission and modulation of nociceptive signals. So the objective of this study was to establish whether low-level laser with different fluence could stimulate the production of nitric oxide synthese (NOS), which produces NO in cultured primary dorsal root ganglion neurons (DRG neurons). The primary DRG neurons were isolated from healthy Sprague Dawley rats (8-12 weeks of age) and spread on 35 mm culture dishes specially used for confocal microscopy. 24 hours after spreading, cells were irradiated with 658 nm laser for two consecutive days at the energy density of 20, 40, 60 and 80 mJ·cm-2 respectively. Control groups were not exposed to the laser, but were kept under the same conditions as the irradiated ones. The synthesis of NOS after laser irradiation was detected by immunofluorescence assay, and the changes of NOS were evaluated using confocal microscopy and Image J software. The results showed that all the laser fluence could promote the production of NOS in DRG neurons, especially the 60 mJ·cm-2 . These results demonstrated that low-level laser irradiation could modify protein synthesis in a dose- or fluence- dependent manner, and indicated that low-level laser irradiation might achieve the analgesic effect through modulation of NO production.

  16. Signal and charge collection efficiency of n-in-p strip detectors after mixed irradiation to HL-LHC fluences

    Kuehn, Susanne; Barber, Thomas; Casse, Gianluigi; Dervan, Paul; Driewer, Adrian; Forshaw, Dean; Huse, Torkjell; Jakobs, Karl; Parzefall, Ulrich

    2013-12-01

    For the year 2020, an upgrade of the LHC with a factor ten increase in luminosity is planned. The resulting severe radiation doses for the ATLAS tracker demand extremely radiation tolerant detectors. In this study six planar n-in-p strip sensors produced by Hamamatsu Photonics were irradiated in consecutive irradiation steps with pions of 280 Mev/c, protons of 25 Mev/c and reactor neutrons resulting in a combined fluence of up to 3×1015 1 MeV neutron equivalent particles per square centimeter (neq /cm2). This particle composition and fluence corresponds to the qualification limit specified by the ATLAS experiment for the outer pixel layers (assuming an integrated luminosity of 3000 fb-1). The 320 μm thick devices are investigated using electrons from a 90Sr source. After each irradiation step both charge collection efficiency and noise measurements have been performed using the ALIBAVA readout system, which is based on analogue Beetle ASICs clocked at 40 MHz. Measurements of the signal and signal-to-noise ratio of detectors will be given after the sensors were exposed to radiation that both in fluence and composition are corresponding to the expectations for the HL-LHC trackers. Conclusions will be drawn on their operation in the ATLAS inner detector upgrade.

  17. Fluence-dependent dynamics of the 5d6s exchange splitting in Gd metal after femtosecond laser excitation

    Frietsch, Björn; Carley, Robert; Gleich, Markus; Teichmann, Martin; Bowlan, John; Weinelt, Martin

    2016-07-01

    We investigate the fluence-dependent dynamics of the exchange-split 5d6s valence bands of Gd metal after femtosecond, near-infrared (IR) laser excitation. Time- and angle-resolved photoelectron spectroscopy (tr-ARPES) with extreme ultraviolet (XUV) probe pulses is used to simultaneously map the transient binding energies of the minority and majority spin valence bands. The decay constant of the exchange splitting increases with fluence. This reflects the slower response of the occupied majority-spin component, which we attribute to Elliot–Yafet spin-flip scattering in accordance with the microscopic three-temperature model (M3TM). In contrast, the time constant of the partly unoccupied minority-spin band stays unaffected by a change in pump fluence. Here, we introduce as an alternative to superdiffusive spin transport exchange scattering, which is an ultrafast electronic mechanism explaining the observed dynamics. Exchange scattering can reduce the spin polarization in the partially unoccupied minority-spin band and thus its energetic position without effective demagnetization.

  18. Standard Test Method for Determining Thermal Neutron Reaction Rates and Thermal Neutron Fluence Rates by Radioactivation Techniques

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 The purpose of this test method is to define a general procedure for determining an unknown thermal-neutron fluence rate by neutron activation techniques. It is not practicable to describe completely a technique applicable to the large number of experimental situations that require the measurement of a thermal-neutron fluence rate. Therefore, this method is presented so that the user may adapt to his particular situation the fundamental procedures of the following techniques. 1.1.1 Radiometric counting technique using pure cobalt, pure gold, pure indium, cobalt-aluminum, alloy, gold-aluminum alloy, or indium-aluminum alloy. 1.1.2 Standard comparison technique using pure gold, or gold-aluminum alloy, and 1.1.3 Secondary standard comparison techniques using pure indium, indium-aluminum alloy, pure dysprosium, or dysprosium-aluminum alloy. 1.2 The techniques presented are limited to measurements at room temperatures. However, special problems when making thermal-neutron fluence rate measurements in high-...

  19. Effects of high thermal and high fast fluences on the mechanical properties of Type 6061 aluminum on the HRBR

    The High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory (BNL) is an epithermal, externally moderated (by D2O) facility designed to produce neutron beams for research. Type 6061 T-6 aluminum was used for the beam tubes pressure vessel, fuel cladding, and most other components in the high flux area. The HFBR has operated since 1965. The epithermal, external moderation of the HFBR means that materials irradiated in different areas of the facility receive widely different flux spectra. Thus, specimens from a control rod drive follower tube (CRDF) have received 1.5 x 1022n/cm2(E > 0.1 MeV) and 3.2 x 1023n/cm2 thermal fluence, while those from a vertical thimble flow shroud received 1.9 x 1023n/cm2 (E > 0.1 MeV) and 1.0 x 1023n/cm2 thermal. These numbers correspond to fast to thermal fluence ratios ranging from 0.05 to 1.9. Irradiations are occurring at approximately 333 K. The data indicate that the increase in tensile strength and decrease in ductility result primarily from the thermal fluence, that is, transmutation of aluminum to silicon

  20. Study of the effects of low-fluence laser irradiation on wall paintings: Test measurements on fresco model samples

    Laser-induced fluorescence is widely applied in several fields as a diagnostic tool to characterise organic and inorganic materials and could be also exploited for non-invasive remote investigation of wall paintings using the fluorescence lidar technique. The latter relies on the use of a low-fluence pulsed UV laser and a telescope to carry out remote spectroscopy on a given target. A first step to investigate the applicability of this technique is to assess the effects of low-fluence laser radiation on wall paintings. This paper presents a study devoted to investigate the effects of pulsed UV laser radiation on a set of fresco model samples prepared using different pigments. To irradiate the samples we used a tripled-frequency Q-switched Nd:YAG laser (emission wavelength: 355 nm; pulse width: 5 ns). We varied the laser fluence from 0.1 mJ/cm2 to 1 mJ/cm2 and the number of laser pulses from 1 to 500 shots. We characterised the investigated materials using several diagnostic and analytical techniques (colorimetry, optical microscopy, fibre optical reflectance spectroscopy and ATR-FT-IR microscopy) to compare the surface texture and their composition before and after laser irradiation. Results open good prospects for a non-invasive investigation of wall paintings using the fluorescence lidar technique.

  1. Study of high-fluence titanium implantation into AISI M2 steel by 48Ti isotopic tracing

    AISI M2 steel was implanted with titanium ions of 110 keV incident energy at room temperature. Fluences were varied from 1 to 4x1017 Ti cm-2. The 48Ti(p, γ)49V resonant nuclear reaction at 1362 keV was used to determine selectively the 48Ti distribution profiles. The γ-rays of 7.936 MeV energy and the related escape peaks were identified and used to quantify the 1362 keV resonance yield. In order to understand the mechanisms taking place during titanium implantation, a high Ti fluence was implanted in several steps made up of, first, a 101748Ti cm-2 dose, followed by several successive 101746Ti cm-2 doses. Thus the evolution of the initially implanted 48Ti distribution was followed as the 46Ti dose increased. On the basis of the experimental results, a primary recoil mixing based model is proposed. The agreement obtained between experimental and theoretical mixing rates suggests that the primary recoil mixing process and the sputtering effect are the most important physical mechanisms during high-fluence Ti implantation into steels. (orig.)

  2. Naphthalene degradation in seawater by UV irradiation: The effects of fluence rate, salinity, temperature and initial concentration

    Highlights: • The removal of naphthalene follows first order kinetics in seawater. • Irradiance and temperature are the most influential factors. • An increase in irradiance can linearly promote photodegradation. • High salinity suppresses the photodegradation of naphthalene. - Abstract: A large amount of oil pollution at sea is produced by the operational discharge of oily wastewater. The removal of polycyclic aromatic hydrocarbons (PAHs) from such sources using UV irradiation has become attractive, yet the photolysis mechanism in seawater has remained unclear. This study examines the photodegradation kinetics of naphthalene in natural seawater through a full factorial design of experiments (DOE). The effects of fluence rate, salinity, temperature and initial concentration are investigated. Results show that fluence rate, temperature and the interaction between temperature and initial concentration are the most influential factors. An increase in fluence rate can linearly promote the photodegradation process. Salinity increasingly impedes the removal of naphthalene because of the existence of free-radical scavengers and photon competitors. The results will help understand the photolysis mechanism of PAHs and develop more effective methods for treating oily seawater generated from offshore industries

  3. Global Monitoring

    Victor Ya. Tsvetkov

    2012-01-01

    The article describes the technology and classification of global monitoring, shows the relationship between the global monitoring and geographic information monitoring, presents the cause-and-effect diagram of global monitoring. The paper discloses the value of the time series for global monitoring, offers a functional diagram of the global monitoring system, gives the main characteristics of global monitoring.

  4. Accumulation of contaminants from urban rainfall runoff in blue crabs: A pilot study

    US Fish and Wildlife Service, Department of the Interior — The objective of this pilot study was to determine the feasibility of using caged blue crabs Callinectes sapidus to monitor accumulation of contaminants in urban...

  5. Research of Mosses Accumulation Properties Used for Assessment of Regional and Local Atmospheric Pollution

    Nadezhda K. Ryzhakova; Rogova, Natalia S.; Borisenko, Alex L.

    2014-01-01

    The monitoring of atmospheric heavy metal and other toxic element depositions by using widespread bryophytes as biomonitors has been widely used. Choosing most appropriate moss species in relation to their accumulation properties is the main goal of this research. The accumulation of heavy metals and other toxic elements by widespread mosses of midland have been studied. The research is focused on assessing accumulation properties of 4 species of terrestrial moss, 4 species of paludal moss an...

  6. Three-dimensional Monte Carlo calculations of the neutron and γ-ray fluences in the TFTR diagnostic basement and comparisons with measurements

    Realistic calculations of the neutron and γ-ray fluences in the TFTR diagnostic basement have been carried out with three-dimensional Monte Carlo models. Comparisons with measurements show that the results are well within the experimental uncertainties

  7. Analysis and comparison of monoenergetic fast neutron fluence determination using {sup 238}U samples at different positions with respect to the neutron source

    Zhang Guohui, E-mail: guohuizhang@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); Liu Xiang; Gao Zhiqi; Wu Hao; Liu Jiaming [State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China)

    2012-05-15

    Using two {sup 238}U samples placed in a gridded ionization chamber and a parallel-plate fission chamber, fluence of monoenergetic fast neutrons was determined. Four runs of measurements were performed. Analysis showed that although the neutron fluences for the two {sup 238}U samples differ by 20-33 times in the present work, the fluences at the position of the sample in the gridded ionization chamber determined by the two ways are in agreement within experimental uncertainties. - Highlights: Black-Right-Pointing-Pointer Fluences of monoenergetic fast neutrons were determined in four runs. Black-Right-Pointing-Pointer One {sup 238}U sample was placed in a gridded ionization chamber. Black-Right-Pointing-Pointer Another {sup 238}U sample was placed in a parallel-plate fission chamber. Black-Right-Pointing-Pointer Results are in agreement for different runs and different detectors.

  8. Three-dimensional Monte Carlo calculations of the neutron and. gamma. -ray fluences in the TFTR diagnostic basement and comparisons with measurements

    Liew, S.L.; Ku, L.P.; Kolibal, J.G.

    1985-10-01

    Realistic calculations of the neutron and ..gamma..-ray fluences in the TFTR diagnostic basement have been carried out with three-dimensional Monte Carlo models. Comparisons with measurements show that the results are well within the experimental uncertainties.

  9. Contribution to time resolved X-ray fluence and differential spectra measurement method improvement in 5-200 KeV range. Application to pulsed emission sources

    Two types of sensors have been developed to measure locally the time-resolved fluence and differential energetic spectrum of pulsed X-ray in the energy range 5 to 200 keV. Rise time of these sensors is very short (10 ns) in order to permit time-resolved measurements. Fluence sensors have been developed by putting filters in front of detector in order to make sensor response independent of X-ray energy and proportional to X-ray fluence. The energetic differential spectrum was calculated by way of a method similar to the ROSS method but using filters separated within a pair defining adjacent spectral width. A detailed analysis of uncertainties affecting calculated fluence and spectrum has been done

  10. Application of the photon-fluence scaling theorem to absorbed dose calorimetry for bremsstrahlung peak energy >1.02 MeV

    Application of the 'photon fluence scaling theorem' allows the ionization chamber to be placed at points in media where the photon fluence is the same, hence eliminating problems with energy response. The theorem is applicable to Compton scattered photons. For photon energies greater than 1.02 MeV, pair production alters the photon fluence in such a way as to invalidate the scaling theorem. In this report the effect of pair production is examined, so that a correction may be applied to the photon fluence scaling theorem. This correction extends application of the theorem for bremsstrahlung spectra up to at least 25 MeV peak energy. 10 refs., 4 tabs., 1 fig

  11. Accumulation of mercury in fish

    In model experiments the direct uptake (excluding the food chain) of different dissolved mercury compounds by female species of Poecilia reticulata was investigated using the radiochemical tracer method. Hg-203 labelled Hg(NO3)2 and CH3HgCl were dissolved in deionized water resulting in concentrations of 0.1/1/5/10 and 20 ng Hg/ml H2O. The fish were measured in vivo using a 3'' x 3'' NaI(Tl) well-type-detector. The experiments showed, that the accumulation rate (ng Hg/g/sub fi/. d) depends very much on the chemical form and the concentration of the dissolved Hg-compound. The accumulation in a CH3HgCl-solution is about four times as fast as in a Hg(NO3)2- solution. In the presence of complexing agents the accumulation rates decrease whereas the accumulation rates increase with increasing Hg-concentration in the water. The release of incorporated methylmercury has a half life of about 69 days. For inorganic mercury a two step mechanism has been found with half lives of 4 days and 68 days, respectively. The relative amount of mercury released in the second step increases with increasing time of incorporation. This indicates the methylation of inorganic mercury in the fish

  12. Pension funds and capital accumulation

    Belan, Pascal; Michel, Philippe; Wigniolle, Bertrand

    2001-01-01

    This note presents a model in which pension funds, by holding a signifiant share of capital assets, can exert a non competitive behavior on labor market. This leads to lower wages and higher capital returns, and can reduce capital accumulation and Long-run welfare.

  13. The Fluence Effects of Low-Level Laser Therapy on Inflammation, Fibroblast-Like Synoviocytes, and Synovial Apoptosis in Rats with Adjuvant-Induced Arthritis

    Hsieh, Yueh-Ling; Cheng, Yu-Jung; Huang, Fang-Chuen; Yang, Chen-Chia

    2014-01-01

    Objective: The aim of this study was to evaluate the effect of low-level laser therapy (LLLT) operating at low and high fluences on joint inflammation, fibroblast-like synoviocytes (FLS), and synovial apoptosis in rats with adjuvant-induced arthritis. Background data: Rheumatoid arthritis (RA) is characterized by pronounced inflammation and FLS proliferation within affected joints. Certain data indicate that LLLT is effective in patients with inflammation caused by RA; however, the fluence ef...

  14. Verification of the algorithm of sum of fluences for quality control in IMRT; Verificacion del algoritmo de suma de fluencias para control de calidad en IMRT

    Candela Rodriguez, F.; Camara Turbi, A.; Melchor Iniguez, M.; Martinez Rodriguez, D.

    2013-07-01

    In prior to each IMRT treatment quality control measures face are made to verify the match between the Royal treatment and details of the Planner. verified values of absolute dose at different points of a mannequin, the distribution of doses of all the fields (individual fluences), and the distribution of dose in the treatment full (global creep). This paper compares the distribution of doses for the full treatment measurement with that obtained by combining data from the fluences of the individual fields. (Author)

  15. A real-time virtual delivery system for photon radiotherapy delivery monitoring

    Feng Shi

    2014-03-01

    Full Text Available Purpose: Treatment delivery monitoring is important for radiotherapy, which enables catching dosimetric error at the earliest possible opportunity. This project develops a virtual delivery system to monitor the dose delivery process of photon radiotherapy in real-time using GPU-based Monte Carlo (MC method.Methods: The simulation process consists of 3 parallel CPU threads. A thread T1 is responsible for communication with a linac, which acquires a set of linac status parameters, e.g. gantry angles, MLC configurations, and beam MUs every 20 ms. Since linac vendors currently do not offer interface to acquire data in real time, we mimic this process by fetching information from a linac dynalog file at the set frequency. Instantaneous beam fluence map (FM is calculated based. A FM buffer is also created in T1 and the instantaneous FM is accumulated to it. This process continues, until a ready signal is received from thread T2 on which an in-house developed MC dose engine executes on GPU. At that moment, the accumulated FM is transferred to T2 for dose calculations, and the FM buffer in T1 is cleared. Once the dose calculation finishes, the resulting 3D dose distribution is directed to thread T3, which displays it in three orthogonal planes in color wash overlaid on the CT image. This process continues to monitor the 3D dose distribution in real-time.Results: An IMRT and a VMAT cases used in our patient-specific QA are studied. Maximum dose differences between our system and treatment planning system are 0.98% and 1.58% for the IMRT and VMAT cases, respectively. The update frequency is >10Hz and the relative uncertainty level is 2%.Conclusion: By embedding a GPU-based MC code in a novel data/work flow, it is possible to achieve real-time MC dose calculations to monitor delivery process.------------------------------Cite this article as: Shi F, Gu X, Graves YJ, Jiang S, Jia X. A real-time virtual delivery system for photon radiotherapy delivery

  16. Low versus High Fluence Parameters in the Treatment of Facial Laceration Scars with a 1,550 nm Fractional Erbium-Glass Laser

    Hyung-Sup Shim

    2015-01-01

    Full Text Available Purpose. Early postoperative fractional laser treatment has been used to reduce scarring in many institutions, but the most effective energy parameters have not yet been established. This study sought to determine effective parameters in the treatment of facial laceration scars. Methods. From September 2012 to September 2013, 57 patients were enrolled according to the study. To compare the low and high fluence parameters of 1,550 nm fractional erbium-glass laser treatment, we virtually divided the scar of each individual patient in half, and each half was treated with a high and low fluence setting, respectively. A total of four treatment sessions were performed at one-month intervals and clinical photographs were taken at every visit. Results. Results were assessed using the Vancouver Scar Scale (VSS and global assessment of the two portions of each individual scar. Final evaluation revealed that the portions treated with high fluence parameter showed greater difference compared to pretreatment VSS scores and global assessment values, indicating favorable cosmetic results. Conclusion. We compared the effects of high fluence and low fluence 1,550 nm fractional erbium-glass laser treatment for facial scarring in the early postoperative period and revealed that the high fluence parameter was more effective for scar management.

  17. A method to improve fluence resolution derived from two-dimensional detector array measurements for patient-specific IMRT verification using the information collected in dynalog files

    Juan Agustin Calama Santiago

    2015-01-01

    Full Text Available This paper proposes a method for improving the resolution of the fluence derived from detector array measurement using the information collected in dynalog files. From dynalog information, a file is generated with the actual multileaf collimator (MLC positions and used as input to the treatment planning system (TPS to obtain the dynalog-derived fluence and the theoretical response over the detector array. In contrast with the measured response, this theoretical response allows for correction of the dynalog-derived fluence and translation into the reconstructed fluence. This fluence is again introduced into the planning system to verify the treatment using clinical tools. Initially, more than 98% of the points passed the two-dimensional (2D phantom gamma test (3% local dose - 3 mm for all of the treatment verifications, but in some dose-volume histogram (DVH comparisons, we note sensitive differences for the planning target volume (PTV coverage and for the maximum doses in at-risk organs (up to 3.5%. In dose-distribution evaluations, we found differences of up to 5% in the PTV edges in certain cases due to detector array measurement errors. This work improves the resolution of the fluence derived from detector array measurements based on the treatment information, in contrast with the current commercial proposals based on planned data.

  18. Tailoring out-of-plane magnetic properties of pulsed laser deposited FePt thin films by changing laser energy fluence

    Highlights: • Laser energy fluence (LEF) effect on composition, microstructure and magnetism. • Enhancing out-of-plane magnetic properties by tailoring LEF on target surface. • Higher LEF results in more energetic plasma species causing vacancy defects. • Formation of vacancy defect in FePt thin films leads to improved magnetic properties. • Best out-of-plane magnetic properties are achieved with medium LEF. - Abstract: Magnetic properties of pulsed laser deposited (PLD) FePt thin films are investigated at three different laser energy fluences of 51, 136 and 182 J/cm2. Deposition at lower laser energy fluence (51 J/cm2) yields softer out-of-plane coercivity (≤0.4 kG), whereas deposition at higher laser energy fluence (136 and 182 J/cm2) results in harder out-of-plane coercivity (≥5.0 kG). The improved coercivity is found to be attributed to the formation of vacancy defects in thin films, which is indicated by stress change from tensile to compressive form with increasing laser energy fluence. Maximum out-of-plane saturated magnetization of 615 emu/cm3 and remanent squareness ratio of 0.88 are achieved for 16 nm thick FePt thin films deposited at moderate laser energy fluence of 136 J/cm2, making them suitable for high density perpendicular data storage applications

  19. Monte Carlo study of the depth-dependent fluence perturbation in parallel-plate ionization chambers in electron beams

    Zink, K., E-mail: klemens.zink@kmub.thm.de [Institute of Medical Physics and Radiation Protection (IMPS), University of Applied Sciences Giessen, Giessen D-35390, Germany and Department of Radiotherapy and Radiooncology, University Medical Center Giessen-Marburg, Marburg D-35043 (Germany); Czarnecki, D.; Voigts-Rhetz, P. von [Institute of Medical Physics and Radiation Protection (IMPS), University of Applied Sciences Giessen, Giessen D-35390 (Germany); Looe, H. K. [Clinic for Radiation Therapy, Pius-Hospital, Oldenburg D-26129, Germany and WG Medical Radiation Physics, Carl von Ossietzky University, Oldenburg D-26129 (Germany); Harder, D. [Prof. em., Medical Physics and Biophysics, Georg August University, Göttingen D-37073 (Germany)

    2014-11-01

    Purpose: The electron fluence inside a parallel-plate ionization chamber positioned in a water phantom and exposed to a clinical electron beam deviates from the unperturbed fluence in water in absence of the chamber. One reason for the fluence perturbation is the well-known “inscattering effect,” whose physical cause is the lack of electron scattering in the gas-filled cavity. Correction factors determined to correct for this effect have long been recommended. However, more recent Monte Carlo calculations have led to some doubt about the range of validity of these corrections. Therefore, the aim of the present study is to reanalyze the development of the fluence perturbation with depth and to review the function of the guard rings. Methods: Spatially resolved Monte Carlo simulations of the dose profiles within gas-filled cavities with various radii in clinical electron beams have been performed in order to determine the radial variation of the fluence perturbation in a coin-shaped cavity, to study the influences of the radius of the collecting electrode and of the width of the guard ring upon the indicated value of the ionization chamber formed by the cavity, and to investigate the development of the perturbation as a function of the depth in an electron-irradiated phantom. The simulations were performed for a primary electron energy of 6 MeV. Results: The Monte Carlo simulations clearly demonstrated a surprisingly large in- and outward electron transport across the lateral cavity boundary. This results in a strong influence of the depth-dependent development of the electron field in the surrounding medium upon the chamber reading. In the buildup region of the depth-dose curve, the in–out balance of the electron fluence is positive and shows the well-known dose oscillation near the cavity/water boundary. At the depth of the dose maximum the in–out balance is equilibrated, and in the falling part of the depth-dose curve it is negative, as shown here the

  20. Signal and charge collection efficiency of n-in-p strip detectors after mixed irradiation to HL-LHC fluences

    Kuehn, Susanne, E-mail: susanne.kuehn@cern.ch [Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg (Germany); Barber, Thomas [Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg (Germany); Casse, Gianluigi; Dervan, Paul [Department of Physics, University of Liverpool, The Oliver Lodge Laboratory, Oxford Street L69 7ZE (United Kingdom); Driewer, Adrian [Fraunhofer Institute for Microelectronic Circuits and Systems, Finkenstr. 61, 47057 Duisburg (Germany); Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg (Germany); Forshaw, Dean; Huse, Torkjell [Department of Physics, University of Liverpool, The Oliver Lodge Laboratory, Oxford Street L69 7ZE (United Kingdom); Jakobs, Karl; Parzefall, Ulrich [Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg (Germany)

    2013-12-01

    For the year 2020, an upgrade of the LHC with a factor ten increase in luminosity is planned. The resulting severe radiation doses for the ATLAS tracker demand extremely radiation tolerant detectors. In this study six planar n-in-p strip sensors produced by Hamamatsu Photonics were irradiated in consecutive irradiation steps with pions of 280 Mev/c, protons of 25 Mev/c and reactor neutrons resulting in a combined fluence of up to 3×10{sup 15} 1 MeV neutron equivalent particles per square centimeter (n{sub eq}/cm{sup 2}). This particle composition and fluence corresponds to the qualification limit specified by the ATLAS experiment for the outer pixel layers (assuming an integrated luminosity of 3000 fb{sup −1}). The 320μm thick devices are investigated using electrons from a {sup 90}Sr source. After each irradiation step both charge collection efficiency and noise measurements have been performed using the ALIBAVA readout system, which is based on analogue Beetle ASICs clocked at 40 MHz. Measurements of the signal and signal-to-noise ratio of detectors will be given after the sensors were exposed to radiation that both in fluence and composition are corresponding to the expectations for the HL-LHC trackers. Conclusions will be drawn on their operation in the ATLAS inner detector upgrade. -- Highlights: •Charge collection measurements of n-in-p strip detectors irradiated up to 3E15 n{sub eq}/cm{sup 2}. •Signal reduced from 25 k electrons before irradiation to 9–11 k electrons at 600 V bias. •Signal-to-noise ratio measured above 10 at 600 V after irradiation with pions, protons and neutrons. •N-in-p strip detectors functional for doses in inner strip layers of ATLAS in the HL-LHC. •Results agreeing to results after single particle irradiation.

  1. Response of Ni/4H-SiC Schottky barrier diodes to alpha-particle irradiation at different fluences

    Omotoso, E.; Meyer, W. E.; Auret, F. D.; Diale, M.; Ngoepe, P. N. M.

    2016-01-01

    Irradiation experiments have been carried out on 1.9×1016 cm-3 nitrogen-doped 4H-SiC at room temperature using 5.4 MeV alpha-particle irradiation over a fluence ranges from 2.6×1010 to 9.2×1011 cm-2. Current-voltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements have been carried out to study the change in characteristics of the devices and free carrier removal rate due to alpha-particle irradiation, respectively. As radiation fluence increases, the ideality factors increased from 1.20 to 1.85 but the Schottky barrier height (SBHI-V) decreased from 1.47 to 1.34 eV. Free carrier concentration, Nd decreased with increasing fluence from 1.7×1016 to 1.1×1016 cm-2 at approximately 0.70 μm depth. The reduction in Nd shows that defects were induced during the irradiation and have effect on compensating the free carrier. The free carrier removal rate was estimated to be 6480±70 cm-1. Alpha-particle irradiation introduced two electron traps (E0.39 and E0.62), with activation energies of 0.39±0.03 eV and 0.62±0.08 eV, respectively. The E0.39 as attribute related to silicon or carbon vacancy, while the E0.62 has the attribute of Z1/Z2.

  2. Hadron Fluence Measurements with LiF-TLD Sensors at the Proton Synchrotron Accelerator at CERN

    Ilgner, Christoph; Obryk, Barbara

    2010-01-01

    In view of the implementation of beam-monitoring sensors for CERN's Large Hadron Collider (LHC), and also in order to validate Thermoluminescence Detectors as a versatile tool to measure ionizing radiation doses in mixed fields at hadron colliders such as the LHC, chemical vapor deposition diamond sensors have been evaluated and calibrated at CERN's Proton Synchrotron accelerator. Special attention was paid to understanding whether lithiumfluoride thermoluminescence detectors are suitable as measuring devices in these radiation fields.

  3. Hadron Fluence Measurements with LiF-TLD Sensors at the Proton Synchrotron Accelerator at CERN

    Ilgner, Christoph; Budzanowski, Maciej; Obryk, Barbara

    2010-01-01

    In view of the implementation of beam-monitoring sensors for CERN's Large Hadron Collider (LHC), and also in order to validate Thermoluminescence Detectors as a versatile tool to measure ionizing radiation doses in mixed fields at hadron colliders such as the LHC, chemical vapor deposition diamond sensors have been evaluated and calibrated at CERN's Proton Synchrotron accelerator. Special attention was paid to understanding whether lithiumfluoride thermoluminescence detectors are suitable as ...

  4. High fluence deposition of polyethylene glycol films at 1064 nm by matrix assisted pulsed laser evaporation (MAPLE)

    Purice, Andreea; Schou, Jørgen; Kingshott, P.; Pryds, Nini; Dinescu, M.

    2007-01-01

    microbalance. The laser fluence needed to produce PEG films turned out to be unexpectedly high with a threshold of 9 J/cm(2) and the deposition rate was much lower than that with laser light at 355 nm. Results from matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI......Matrix assisted pulsed laser evaporation (MAPLE) has been applied for deposition of thin polyethylene glycol (PEG) films with infrared laser light at 1064 nm. We have irradiated frozen targets (of 1 wt.% PEG dissolved in water) and measured the deposition rate in situ with a quartz crystal 2...

  5. Towards modeling and validation enhancements of the PSI MCNPX fast neutron fluence computational scheme based on recent PWR experimental data

    Highlights: • V&V studies with CASMO/SIMULATE/MCNPX computation scheme are described. • Fixed-source modeling is used for PWR ex-core Monte Carlo neutron transport. • The reference data includes activity measurements and fluence estimations. • Adjusting the calculation models for the specific validation data sets is discussed. • Obtained results and findings of associated sensitivity studies are reported. - Abstract: At the Paul Scherrer Institute (PSI), a computational scheme aimed at high fidelity fast neutron fluence estimations for Light-Water-Reactors (LWRs) was in previous years developed. In this scheme, the neutron transport calculations are performed with the stochastic Monte Carlo N-Particle Transport Code MCNPX using as basis a three-dimensional pin-level volumetric source obtained from validated deterministic CASMO/SIMULATE models. While first validation studies confirmed a satisfactory performance, the strategy is to continually add new validation cases in order to achieve an enlarged and comprehensive qualification basis that also integrates latest advances in methods and/or nuclear data. Thereby, new sets of experimental data from a Swiss operating pressurized water reactor plant that became available recently were adopted for a further validation of the scheme. The first set consists of 54Mn and 93mNb activity measurements from so-called gradient probes located at an elevation corresponding to the top end of active fuel and increasing thereby the computational challenges because of very strong axial flux gradients. The second set consists of fluence estimates derived from 54Mn and 93mNb activity measurements of scraping samples extracted from the reactor pressure vessel. All dosimeters have been analyzed after the 27th cycle of operation of the reactor, providing thereby an opportunity to assess the computational methodology for modern fuel management schemes. This paper presents the validation study of the PSI fast neutron fluence scheme

  6. The role of natural and UV-induced skin pigmentation on low-fluence IPL-induced side effects

    Thaysen-Petersen, Daniel; Lin, Jennifer Y; Nash, Jf;

    2014-01-01

    were randomized to receive 0 or 8 solar simulated ultraviolet radiation (UVR) exposures of consecutively increasing Standard Erythema Doses (2-4 SED). Each block was subdivided into four sites, randomized to receive IPL of 0, 7, 8, or 10 J/cm(2) , once a week for 3 weeks. Biopsies were taken 16...... disproportionately. The aim of this study was to evaluate the influence of constitutive and facultative skin pigmentation on low-fluence intense pulsed light (IPL)-induced adverse skin effects. STUDY DESIGN/MATERIALS AND METHODS: Twenty-one subjects with Fitzpatrick skin type II-IV were enrolled. Two buttock blocks...

  7. Hypopigmentation Induced by Frequent Low-Fluence, Large-Spot-Size QS Nd:YAG Laser Treatments.

    Wong, Yisheng; Lee, Siong See Joyce; Goh, Chee Leok

    2015-12-01

    The Q-switched 1064-nm neodymium-doped yttrium aluminum garnet (QS 1064-nm Nd:YAG) laser is increasingly used for nonablative skin rejuvenation or "laser toning" for melasma. Multiple and frequent low-fluence, large-spot-size treatments are used to achieve laser toning, and these treatments are associated with the development of macular hypopigmentation as a complication. We present a case series of three patients who developed guttate hypomelanotic macules on the face after receiving laser toning treatment with QS 1064-nm Nd:YAG. PMID:26719647

  8. Comparison of anatomy-based, fluence-based and aperture-based treatment planning approaches for VMAT

    Rao, Min; Cao, Daliang; Chen, Fan; Ye, Jinsong; Mehta, Vivek; Wong, Tony; Shepard, David

    2010-11-01

    Volumetric modulated arc therapy (VMAT) has the potential to reduce treatment times while producing comparable or improved dose distributions relative to fixed-field intensity-modulated radiation therapy. In order to take full advantage of the VMAT delivery technique, one must select a robust inverse planning tool. The purpose of this study was to evaluate the effectiveness and efficiency of VMAT planning techniques of three categories: anatomy-based, fluence-based and aperture-based inverse planning. We have compared these techniques in terms of the plan quality, planning efficiency and delivery efficiency. Fourteen patients were selected for this study including six head-and-neck (HN) cases, and two cases each of prostate, pancreas, lung and partial brain. For each case, three VMAT plans were created. The first VMAT plan was generated based on the anatomical geometry. In the Elekta ERGO++ treatment planning system (TPS), segments were generated based on the beam's eye view (BEV) of the target and the organs at risk. The segment shapes were then exported to Pinnacle3 TPS followed by segment weight optimization and final dose calculation. The second VMAT plan was generated by converting optimized fluence maps (calculated by the Pinnacle3 TPS) into deliverable arcs using an in-house arc sequencer. The third VMAT plan was generated using the Pinnacle3 SmartArc IMRT module which is an aperture-based optimization method. All VMAT plans were delivered using an Elekta Synergy linear accelerator and the plan comparisons were made in terms of plan quality and delivery efficiency. The results show that for cases of little or modest complexity such as prostate, pancreas, lung and brain, the anatomy-based approach provides similar target coverage and critical structure sparing, but less conformal dose distributions as compared to the other two approaches. For more complex HN cases, the anatomy-based approach is not able to provide clinically acceptable VMAT plans while highly

  9. The isotopic composition and fluence of solar-wind nitrogen in a genesis B/C array collector

    Huss, Gary R.; Nagashima, Kazuhide; Jurewicz, Amy J. G.; Burnett, Donald S.; Olinger, Chad T.

    2012-01-01

    We have measured the isotopic composition and fluence of solar-wind nitrogen in a diamond-like-carbon collector from the Genesis B/C array. The B and C collector arrays on the Genesis spacecraft passively collected bulk solar wind for the entire collection period, and there is no need to correct data for instrumental fractionation during collection, unlike data from the Genesis “Concentrator.” This work validates isotopic measurements from the concentrator by Marty et al. (2010, 2011); nitrog...

  10. Comparison of anatomy-based, fluence-based and aperture-based treatment planning approaches for VMAT

    Volumetric modulated arc therapy (VMAT) has the potential to reduce treatment times while producing comparable or improved dose distributions relative to fixed-field intensity-modulated radiation therapy. In order to take full advantage of the VMAT delivery technique, one must select a robust inverse planning tool. The purpose of this study was to evaluate the effectiveness and efficiency of VMAT planning techniques of three categories: anatomy-based, fluence-based and aperture-based inverse planning. We have compared these techniques in terms of the plan quality, planning efficiency and delivery efficiency. Fourteen patients were selected for this study including six head-and-neck (HN) cases, and two cases each of prostate, pancreas, lung and partial brain. For each case, three VMAT plans were created. The first VMAT plan was generated based on the anatomical geometry. In the Elekta ERGO++ treatment planning system (TPS), segments were generated based on the beam's eye view (BEV) of the target and the organs at risk. The segment shapes were then exported to Pinnacle3 TPS followed by segment weight optimization and final dose calculation. The second VMAT plan was generated by converting optimized fluence maps (calculated by the Pinnacle3 TPS) into deliverable arcs using an in-house arc sequencer. The third VMAT plan was generated using the Pinnacle3 SmartArc IMRT module which is an aperture-based optimization method. All VMAT plans were delivered using an Elekta Synergy linear accelerator and the plan comparisons were made in terms of plan quality and delivery efficiency. The results show that for cases of little or modest complexity such as prostate, pancreas, lung and brain, the anatomy-based approach provides similar target coverage and critical structure sparing, but less conformal dose distributions as compared to the other two approaches. For more complex HN cases, the anatomy-based approach is not able to provide clinically acceptable VMAT plans while highly

  11. Combination therapy of low-fluence photodynamic therapy and intravitreal ranibizumab for choroidal neovascular membrane in choroidal osteoma

    Rodney J Morris

    2011-01-01

    Full Text Available Choroidal osteoma is an unusual form of intraocular calcification seen in otherwise healthy eyes. It is a benign idiopathic osseous tumor of the choroid, typically seen in young females. Choroidal neovascular membrane (CNVM is a complication seen in one-third of these patients and carries a poor visual outcome. We report a case of a 25-year-old hyperthyroid female with choroidal osteoma and subfoveal CNVM in her left eye which was successfully treated using low-fluence photodynamic therapy (PDT with verteporfin followed by a single injection of intravitreal ranibizumab.

  12. Comparison of anatomy-based, fluence-based and aperture-based treatment planning approaches for VMAT

    Rao Min; Cao Daliang; Chen Fan; Ye Jinsong; Mehta, Vivek; Wong, Tony; Shepard, David, E-mail: min.mrao@gmail.co [Department of Radiation Oncology, Swedish Cancer Institute, 1221 Madison St Seattle, WA 98104 (United States)

    2010-11-07

    Volumetric modulated arc therapy (VMAT) has the potential to reduce treatment times while producing comparable or improved dose distributions relative to fixed-field intensity-modulated radiation therapy. In order to take full advantage of the VMAT delivery technique, one must select a robust inverse planning tool. The purpose of this study was to evaluate the effectiveness and efficiency of VMAT planning techniques of three categories: anatomy-based, fluence-based and aperture-based inverse planning. We have compared these techniques in terms of the plan quality, planning efficiency and delivery efficiency. Fourteen patients were selected for this study including six head-and-neck (HN) cases, and two cases each of prostate, pancreas, lung and partial brain. For each case, three VMAT plans were created. The first VMAT plan was generated based on the anatomical geometry. In the Elekta ERGO++ treatment planning system (TPS), segments were generated based on the beam's eye view (BEV) of the target and the organs at risk. The segment shapes were then exported to Pinnacle{sup 3} TPS followed by segment weight optimization and final dose calculation. The second VMAT plan was generated by converting optimized fluence maps (calculated by the Pinnacle{sup 3} TPS) into deliverable arcs using an in-house arc sequencer. The third VMAT plan was generated using the Pinnacle{sup 3} SmartArc IMRT module which is an aperture-based optimization method. All VMAT plans were delivered using an Elekta Synergy linear accelerator and the plan comparisons were made in terms of plan quality and delivery efficiency. The results show that for cases of little or modest complexity such as prostate, pancreas, lung and brain, the anatomy-based approach provides similar target coverage and critical structure sparing, but less conformal dose distributions as compared to the other two approaches. For more complex HN cases, the anatomy-based approach is not able to provide clinically acceptable

  13. A Systematic Analysis of Coal Accumulation Process

    CHENG Aiguo

    2008-01-01

    Formation of coal seam and coal-rich zone is an integrated result of a series of factors in coal accumulation process. The coal accumulation system is an architectural aggregation of coal accumulation factors. It can be classified into 4 levels: the global coal accumulation super-system, the coal accumulation domain mega.system, the coal accumulation basin system, and the coal seam or coal seam set sub-system. The coal accumulation process is an open, dynamic, and grey system, and is meanwhile a system with such natures as aggregation, relevance, entirety, purpose-orientated, hierarchy, and environment adaptability. In this paper, we take coal accumulation process as a system to study origin of coal seam and coal-rich zone; and we will discuss a methodology of the systematic analysis of coal accumulation process. As an example, the Ordos coal basin was investigated to elucidate the application of the method of the coal accumulation system analysis.

  14. Metal accumulating plants: Medium's role

    Rabier, J.; Prudent, P.; Szymanska, B.; Mevy, J.-P.

    2003-05-01

    To evaluate phytoremediation potentialities by metal accumulation in tolerant plants, trials are carried out using in vitro cultures. Organie compounds influence on metal accumulation is studied with metals supplemented media. The tested compounds on zinc and lead absorption by Brassica juncea, are chelating agents (EDTA, citric acid) and soluble organic fractions of compost. EDTA seems to enhance the transfer of lead in plant but it is the opposite in the case of zinc. Citric acid stimulates root absorption for both zinc and lead. For the aqueous extracts of compost, variable effects are obtained according to the origin of compost (green wastes and food wastes). In'all tested conditions of cultures, zinc is mainly exported towards shoot while lead is stored in root.

  15. Exercise bicycle for accumulator charging

    Nekvapil, Jan

    2014-01-01

    Bachelor thesis is about possible solution construction of exercise bicycle with electric part working as a electric source. The first part of document introduces readers to issues about lead acid accumulators and charging, electronically commutated motors and electric converters. The second part shows potential solving constitution of exercise bicycle and we choose components and devices. EC motor will be connected with exercise bicycle by chain transmission. Transfer energy is realized thro...

  16. Crises and human capital accumulation

    Freddy Heylen; Lorenzo Pozzi

    2007-01-01

    This paper studies the effects of crises on human capital formation. Theoretically, a crisis undermines total factor productivity, which reduces the return to working and to accumulating physical capital. If the crisis is temporary, young agents will study now and work later. Human capital rises. To test our model we rely on inflation crises as our main empirical proxy. Using GMM panel procedures, our analysis for 86 countries in 1970-2000 confirms the positive effects of crises on human capi...

  17. Debt Redemption and Reserve Accumulation

    Laura Alfaro; Fabio Kanczuk

    2013-01-01

    Foreign participation in local-currency bond markets in emerging countries has increased dramatically over the past decade. In light of this trend, we revisit sovereign debt sustainability and incentives to default when the sovereign is temporarily excluded from capital markets. Differently from previous analyses, we assume that in addition to accumulating international reserves, countries can borrow internationally using their own currency. As opposed to traditional sovereign debt models (al...

  18. Accumulation of stress in constrained assemblies: novel Satoh test configuration

    Shirzadi, A. A.; Bhadeshia, H. K. D. H.

    2010-01-01

    A common test used to study the response of a transforming material to external constraint is due to Satoh and involves the cooling of a rigidly constrained tensile specimen while monitoring the stress that accumulates. Such tests are currently common in the invention of welding alloys which on phase transformation lead to a reduction in residual stresses in the final assembly. The test suffers from the fact that the whole of the tensile specimen is not maintained at a uniform temperature, ma...

  19. A new neutron monitor and extended conversion coefficients for Hp(10)

    Full text: A new personal dose equivalent monitor is introduced which consists of a 30 cm x 30 cm x 15 cm PMMA slab hosting a superheated drop detector embedded at a depth of 10 mm. The device relies on the similarity between the fluence response of neutron superheated drop detectors based on halocarbon-12 and the quality-factor-weighted kerma factor. This implies that these detectors can be used for in-phantom dosimetry and provide a direct reading of dose equivalent at depth. The personal dose equivalent monitor was characterized experimentally with fast neutron calibrations in the 0.144-14.8 MeV range and numerically with Monte Carlo simulations. The simulations determined the spectral neutron fluence impinging on the embedded detector upon irradiation of the PMMA slab at several orientations. These spectra were folded with the free-in-air fluence response of the bare detector. The fluence response was thus determined at angles of 0, 45, 90, 135 and 180 degrees for thermal to 20 MeV neutrons. In order to evaluate the performance of the device, its response was compared to the fluence-to-personal dose equivalent conversion coefficients, hp(10;α,E). Since published coefficients only cover neutron angles of incidence up to 75 degrees, a new extended set of coefficients was computed for angles of incidence of 85, 90, 95, 105, 135 and 180 degrees. The method used in these calculations was the very same used in the generation of the dose equivalent coefficients recommended by ICRP publication 74. The response of our monitor was found to the trend of these conversion coefficients with good approximation. Therefore, the device is suitable for a direct measurement of neutron personal dose equivalent, Hp(10), regardless of angle and energy distribution of the neutron fluence. (author)

  20. Trapping in proton irradiated p+-n-n+ silicon sensors at fluences anticipated at the HL-LHC outer tracker

    Adam, W.; Bergauer, T.; Dragicevic, M.; Friedl, M.; Fruehwirth, R.; Hoch, M.; Hrubec, J.; Krammer, M.; Treberspurg, W.; Waltenberger, W.; Alderweireldt, S.; Beaumont, W.; Janssen, X.; Luyckx, S.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Barria, P.; Caillol, C.; Clerbaux, B.; De Lentdecker, G.; Dobur, D.; Favart, L.; Grebenyuk, A.; Lenzi, Th.; Léonard, A.; Maerschalk, Th.; Mohammadi, A.; Perniè, L.; Randle-Conde, A.; Reis, T.; Seva, T.; Thomas, L.; Vander Velde, C.; Vanlaer, P.; Wang, J.; Zenoni, F.; Abu Zeid, S.; Blekman, F.; De Bruyn, I.; D'Hondt, J.; Daci, N.; Deroover, K.; Heracleous, N.; Keaveney, J.; Lowette, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Tavernier, S.; Van Mulders, P.; Van Onsem, G.; Van Parijs, I.; Strom, D. A.; Basegmez, S.; Bruno, G.; Castello, R.; Caudron, A.; Ceard, L.; De Callatay, B.; Delaere, C.; Du Pree, T.; Forthomme, L.; Giammanco, A.; Hollar, J.; Jez, P.; Michotte, D.; Nuttens, C.; Perrini, L.; Pagano, D.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Härkönen, J.; Lampén, T.; Luukka, P.-R.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuovinen, E.; Eerola, P.; Tuuva, T.; Beaulieu, G.; Boudoul, G.; Combaret, C.; Contardo, D.; Gallbit, G.; Lumb, N.; Mathez, H.; Mirabito, L.; Perries, S.; Sabes, D.; Vander Donckt, M.; Verdier, P.; Viret, S.; Zoccarato, Y.; Agram, J.-L.; Conte, E.; Fontaine, J.-Ch.; Andrea, J.; Bloch, D.; Bonnin, C.; Brom, J.-M.; Chabert, E.; Charles, L.; Goetzmann, Ch.; Gross, L.; Hosselet, J.; Mathieu, C.; Richer, M.; Skovpen, K.; Pistone, C.; Fluegge, G.; Kuensken, A.; Geisler, M.; Pooth, O.; Stahl, A.; Autermann, C.; Edelhoff, M.; Esser, H.; Feld, L.; Karpinski, W.; Klein, K.; Lipinski, M.; Ostapchuk, A.; Pierschel, G.; Preuten, M.; Raupach, F.; Sammet, J.; Schael, S.; Schwering, G.; Wittmer, B.; Wlochal, M.; Zhukov, V.; Bartosik, N.; Behr, J.; Burgmeier, A.; Calligaris, L.; Dolinska, G.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Fluke, G.; Garay Garcia, J.; Gizhko, A.; Hansen, K.; Harb, A.; Hauk, J.; Kalogeropoulos, A.; Kleinwort, C.; Korol, I.; Lange, W.; Lohmann, W.; Mankel, R.; Maser, H.; Mittag, G.; Muhl, C.; Mussgiller, A.; Nayak, A.; Ntomari, E.; Perrey, H.; Pitzl, D.; Schroeder, M.; Seitz, C.; Spannagel, S.; Zuber, A.; Biskop, H.; Blobel, V.; Buhmann, P.; Centis-Vignali, M.; Draeger, A.-R.; Erfle, J.; Garutti, E.; Haller, J.; Hoffmann, M.; Junkes, A.; Lapsien, T.; Mättig, S.; Matysek, M.; Perieanu, A.; Poehlsen, J.; Poehlsen, T.; Scharf, Ch.; Schleper, P.; Schmidt, A.; Sola, V.; Steinbrück, G.; Wellhausen, J.; Barvich, T.; Barth, Ch.; Boegelspacher, F.; De Boer, W.; Butz, E.; Casele, M.; Colombo, F.; Dierlamm, A.; Eber, R.; Freund, B.; Hartmann, F.; Hauth, Th.; Heindl, S.; Hoffmann, K.-H.; Husemann, U.; Kornmeyer, A.; Mallows, S.; Muller, Th.; Nuernberg, A.; Printz, M.; Simonis, H. J.; Steck, P.; Weber, M.; Weiler, Th.; Bhardwaj, A.; Kumar, A.; Kumar, A.; Ranjan, K.; Bakhshiansohl, H.; Behnamian, H.; Khakzad, M.; Naseri, M.; Cariola, P.; De Robertis, G.; Fiore, L.; Franco, M.; Loddo, F.; Sala, G.; Silvestris, L.; Creanza, D.; De Palma, M.; Maggi, G.; My, S.; Selvaggi, G.; Albergo, S.; Cappello, G.; Chiorboli, M.; Costa, S.; Giordano, F.; Di Mattia, A.; Potenza, R.; Saizu, M. A.; Tricomi, A.; Tuvè, C.; Barbagli, G.; Brianzi, M.; Ciaranfi, R.; Civinini, C.; Gallo, E.; Meschini, M.; Paoletti, S.; Sguazzoni, G.; Ciulli, V.; D'Alessandro, R.; Gonzi, S.; Gori, V.; Focardi, E.; Lenzi, P.; Scarlini, E.; Tropiano, A.; Viliani, L.; Ferro, F.; Robutti, E.; Lo Vetere, M.; Gennai, S.; Malvezzi, S.; Menasce, D.; Moroni, L.; Pedrini, D.; Dinardo, M.; Fiorendi, S.; Manzoni, R. A.; Azzi, P.; Bacchetta, N.; Bisello, D.; Dall'Osso, M.; Dorigo, T.; Giubilato, P.; Pozzobon, N.; Tosi, M.; Zucchetta, A.; De Canio, F.; Gaioni, L.; Manghisoni, M.; Nodari, B.; Re, V.; Traversi, G.; Comotti, D.; Ratti, L.; Bilei, G. M.; Bissi, L.; Checcucci, B.; Magalotti, D.; Menichelli, M.; Saha, A.; Servoli, L.; Storchi, L.; Biasini, M.; Conti, E.; Ciangottini, D.; Fanò, L.; Lariccia, P.; Mantovani, G.; Passeri, D.; Placidi, P.; Salvatore, M.; Santocchia, A.; Solestizi, L. A.; Spiezia, A.; Androsov, K.; Azzurri, P.; Arezzini, S.; Bagliesi, G.; Basti, A.; Boccali, T.; Bosi, F.; Castaldi, R.; Ciampa, A.; Ciocci, M. A.; Dell'Orso, R.; Fedi, G.; Giassi, A.; Grippo, M. T.; Lomtadze, T.; Magazzu, G.; Mazzoni, E.; Minuti, M.; Moggi, A.; Moon, C. S.; Morsani, F.; Palla, F.; Palmonari, F.; Raffaelli, F.; Savoy-Navarro, A.; Serban, A. T.; Spagnolo, P.; Tenchini, R.; Venturi, A.; Verdini, P. G.; Martini, L.; Messineo, A.; Rizzi, A.; Tonelli, G.; Calzolari, F.; Donato, S.; Fiori, F.; Ligabue, F.; Vernieri, C.; Demaria, N.; Rivetti, A.; Bellan, R.; Casasso, S.; Costa, M.; Covarelli, R.; Migliore, E.; Monteil, E.; Musich, M.; Pacher, L.; Ravera, F.; Romero, A.; Solano, A.; Trapani, P.; Jaramillo Echeverria, R.; Fernandez, M.; Gomez, G.; Moya, D.; Gonzalez Sanchez, F. J.; Munoz Sanchez, F. J.; Vila, I.; Virto, A. L.; Abbaneo, D.; Ahmed, I.; Albert, E.; Auzinger, G.; Berruti, G.; Bianchi, G.; Blanchot, G.; Breuker, H.; Ceresa, D.; Christiansen, J.; Cichy, K.; Daguin, J.; D'Alfonso, M.; D'Auria, A.; Detraz, S.; De Visscher, S.; Deyrail, D.; Faccio, F.; Felici, D.; Frank, N.; Gill, K.; Giordano, D.; Harris, P.; Honma, A.; Kaplon, J.; Kornmayer, A.; Kottelat, L.; Kovacs, M.; Mannelli, M.; Marchioro, A.; Marconi, S.; Martina, S.; Mersi, S.; Michelis, S.; Moll, M.; Onnela, A.; Pakulski, T.; Pavis, S.; Peisert, A.; Pernot, J.-F.; Petagna, P.; Petrucciani, G.; Postema, H.; Rose, P.; Rzonca, M.; Stoye, M.; Tropea, P.; Troska, J.; Tsirou, A.; Vasey, F.; Vichoudis, P.; Verlaat, B.; Zwalinski, L.; Bachmair, F.; Becker, R.; Bäni, L.; di Calafiori, D.; Casal, B.; Djambazov, L.; Donega, M.; Dünser, M.; Eller, P.; Grab, C.; Hits, D.; Horisberger, U.; Hoss, J.; Kasieczka, G.; Lustermann, W.; Mangano, B.; Marionneau, M.; Martinez Ruiz del Arbol, P.; Masciovecchio, M.; Perrozzi, L.; Roeser, U.; Rossini, M.; Starodumov, A.; Takahashi, M.; Wallny, R.; Amsler, C.; Bösiger, K.; Caminada, L.; Canelli, F.; Chiochia, V.; de Cosa, A.; Galloni, C.; Hreus, T.; Kilminster, B.; Lange, C.; Maier, R.; Ngadiuba, J.; Pinna, D.; Robmann, P.; Taroni, S.; Yang, Y.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Kaestli, H.-C.; Kotlinski, D.; Langenegger, U.; Meier, B.; Rohe, T.; Streuli, S.; Chen, P.-H.; Dietz, C.; Grundler, U.; Hou, W.-S.; Lu, R.-S.; Moya, M.; Wilken, R.; Cussans, D.; Flacher, H.; Goldstein, J.; Grimes, M.; Jacob, J.; Seif El Nasr-Storey, S.; Cole, J.; Hobson, P.; Leggat, D.; Reid, I. D.; Teodorescu, L.; Bainbridge, R.; Dauncey, P.; Fulcher, J.; Hall, G.; Magnan, A.-M.; Pesaresi, M.; Raymond, D. M.; Uchida, K.; Coughlan, J. A.; Harder, K.; Ilic, J.; Tomalin, I. R.; Garabedian, A.; Heintz, U.; Narain, M.; Nelson, J.; Sagir, S.; Speer, T.; Swanson, J.; Tersegno, D.; Watson-Daniels, J.; Chertok, M.; Conway, J.; Conway, R.; Flores, C.; Lander, R.; Pellett, D.; Ricci-Tam, F.; Squires, M.; Thomson, J.; Burt, K.; Ellison, J.; Hanson, G.; Malberti, M.; Olmedo, M.; Cerati, G.; Sharma, V.; Vartak, A.; Yagil, A.; Zevi Della Porta, G.; Dutta, V.; Gouskos, L.; Incandela, J.; Kyre, S.; McColl, N.; Mullin, S.; White, D.; Cumalat, J. P.; Ford, W. T.; Gaz, A.; Krohn, M.; Stenson, K.; Wagner, S. R.; Baldin, B.; Bolla, G.; Burkett, K.; Butler, J.; Cheung, H.; Chramowicz, J.; Christian, D.; Cooper, W. E.; Deptuch, G.; Derylo, G.; Gingu, C.; Gruenendahl, S.; Hasegawa, S.; Hoff, J.; Howell, J.; Hrycyk, M.; Jindariani, S.; Johnson, M.; Jung, A.; Joshi, U.; Kahlid, F.; Lei, C. M.; Lipton, R.; Liu, T.; Los, S.; Matulik, M.; Merkel, P.; Nahn, S.; Prosser, A.; Rivera, R.; Shenai, A.; Spiegel, L.; Tran, N.; Uplegger, L.; Voirin, E.; Yin, H.; Adams, M. R.; Berry, D. R.; Evdokimov, A.; Evdokimov, O.; Gerber, C. E.; Hofman, D. J.; Kapustka, B. K.; O'Brien, C.; Sandoval Gonzalez, D. I.; Trauger, H.; Turner, P.; Parashar, N.; Stupak, J.; Bortoletto, D.; Bubna, M.; Hinton, N.; Jones, M.; Miller, D. H.; Shi, X.; Tan, P.; Baringer, P.; Bean, A.; Benelli, G.; Gray, J.; Majumder, D.; Noonan, D.; Sanders, S.; Stringer, R.; Ivanov, A.; Makouski, M.; Skhirtladze, N.; Taylor, R.; Anderson, I.; Fehling, D.; Gritsan, A.; Maksimovic, P.; Martin, C.; Nash, K.; Osherson, M.; Swartz, M.; Xiao, M.; Acosta, J. G.; Cremaldi, L. M.; Oliveros, S.; Perera, L.; Summers, D.; Bloom, K.; Bose, S.; Claes, D. R.; Dominguez, A.; Fangmeier, C.; Gonzalez Suarez, R.; Meier, F.; Monroy, J.; Hahn, K.; Sevova, S.; Sung, K.; Trovato, M.; Bartz, E.; Duggan, D.; Halkiadakis, E.; Lath, A.; Park, M.; Schnetzer, S.; Stone, R.; Walker, M.; Malik, S.; Mendez, H.; Ramirez Vargas, J. E.; Alyari, M.; Dolen, J.; George, J.; Godshalk, A.; Iashvili, I.; Kaisen, J.; Kharchilava, A.; Kumar, A.; Rappoccio, S.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; Kaufman, G.; Mirman, N.; Ryd, A.; Salvati, E.; Skinnari, L.; Thom, J.; Thompson, J.; Tucker, J.; Winstrom, L.; Akgün, B.; Ecklund, K. M.; Nussbaum, T.; Zabel, J.; Betchart, B.; Covarelli, R.; Demina, R.; Hindrichs, O.; Petrillo, G.; Eusebi, R.; Osipenkov, I.; Perloff, A.; Ulmer, K. A.; Delannoy, A. G.; D'Angelo, P.; Johns, W.

    2016-04-01

    The degradation of signal in silicon sensors is studied under conditions expected at the CERN High-Luminosity LHC. 200 μm thick n-type silicon sensors are irradiated with protons of different energies to fluences of up to 3 · 1015 neq/cm2. Pulsed red laser light with a wavelength of 672 nm is used to generate electron-hole pairs in the sensors. The induced signals are used to determine the charge collection efficiencies separately for electrons and holes drifting through the sensor. The effective trapping rates are extracted by comparing the results to simulation. The electric field is simulated using Synopsys device simulation assuming two effective defects. The generation and drift of charge carriers are simulated in an independent simulation based on PixelAV. The effective trapping rates are determined from the measured charge collection efficiencies and the simulated and measured time-resolved current pulses are compared. The effective trapping rates determined for both electrons and holes are about 50% smaller than those obtained using standard extrapolations of studies at low fluences and suggest an improved tracker performance over initial expectations.

  1. A method to detect low-level 63Ni activity for estimating fast neutron fluence from the Hiroshima atomic bomb.

    Ito, Y; Shibata, T; Imamura, M; Shibata, S; Nogawa, N; Uwamino, Y; Shizuma, K

    1999-06-01

    The Hiroshima and Nagasaki atomic bombs resulted in the worst reported exposure of radiation to the human body. The data of survivors have provided the basis for the risk estimation for ionizing radiation, and thus are widely used as the basis of radiation safety. In this report we have studied a new method to detect the low-level 63Ni activity in copper samples in order to estimate the fast neutron fluence from the Hiroshima atomic bomb. Only 0.8 x 10(-3) Bq g(-1) of 63Ni is expected to be produced by the atomic bomb in a copper sample with the 63Cu(n, p)63Ni reaction at a distance of 500 m from the hypocenter. Our method has the required level of sensitivity for determination of the fast neutron fluence out to distances of at least 500 m, and perhaps as far as 1,000 m. We have already investigated and collected some bomb-irradiated copper samples for further study. PMID:10334579

  2. Characterization of n-GaN dilute magnetic semiconductors by cobalt ions implantation at high-fluence

    In this study, we present the structural and magnetic characteristics of cobalt ions implantation at a high-fluence (5×1016 cm−2) into n-GaN epilayer of thickness about 1.6 μm. The n-GaN was grown on sapphire by metal organic chemical vapor deposition (MOCVD). Rutherford backscattering channeling was used for the structural study. After implantation, samples were annealed at 700, 800 and 900 °C by rapid thermal annealing in ambient N2. XRD measurements did not show any secondary phase or metal related-peaks. High resolution X-ray diffraction (HRXRD) was performed as well to characterize structures. Well-defined hysteresis loops were observed at 5 K and room temperature using alternating gradient magnetometer AGM and Superconducting Quantum Interference Device (SQUID) magnetometer. Temperature-dependent magnetization indicated magnetic moment at the lowest temperatures and retained magnetization up to 380 K for cobalt-ion-implanted samples. - Highlights: ► Experiment started with MOCVD grown semiconducting material GaN. ► GaN was implanted with cobalt ions (Co+) of dose 5×1016 cm−2 at room temperature. ► Structural characterization was performed by RBS, XRD and HR-XRD. ► Magnetic properties were observed by AGM and SQUID measurements. ► High TC dilute magnetic semiconductors has been observed up to 380 K for cobalt implanted GaN at high-fluence (5×1016 cm−2).

  3. Fluence to effective dose conversion coefficients for neutrons: a comparison between results obtained by MCNP and FLUKA codes

    Conversion coefficients from fluence to effective dose are calculated by radiation transport codes using mathematical models of the adult human, the so called anthropomorphic phantoms. A comparison using different codes is always important to discover limits and bugs in the computational methods of the codes. Two well-known radiation transport codes, MCNP and FLUKA, have been compared calculating the conversion coefficients from neutron fluence to effective dose using an identical model of an hermaphrodite phantom. Monoenergetic neutrons of energy ranging from 10 keV to 15 MeV plus Maxwellian distributed 0.025 eV neutrons were used with various irradiation geometries. The agreement is generally satisfactory in the energy range 10 keV-10MeV, although differences as large as 20% can be observed for posterior-anterior irradiation. At thermal energy and at 15 MeV discrepancies up to 25% and 15% respectively, are found for all the irradiation geometries investigated. These results are discussed and some considerations about the various contributions of the radiation involved to the effective dose are exposed. (Author)

  4. Bystander effects induced by the low-fluence irradiation of carbon and iron ions (6 MeV/n)

    Many reports are available regarding bystander effects after exposure to low fluences of alpha particles and helium ions. However, few studies have examined bystander cellular effects after exposure to low fluences of ion species heavier than helium. We has been investigating bystander effects using both human normal fibroblasts and tumor cell lines irradiated with low energy (6 MeV/n) carbon or iron ions generated with the Medium Energy Beam Course. This year we focused on the bystander cellular effects as follows; Bystander cell-killing effect in human tumor cell lines irradiated with carbon ions. Relationship of bystander lethal effect between p53-wild and p53-mutated cells. Bystander cell-killing effect was observed in human normal and tumor cells harboring wild-type p53, but not in p53-mutated tumor cells. Moreover, observed bystander effect was suppressed by treating with a specific inhibitor of gap-junction mediated cell-cell communication. There is evidence that p53- and gap-junction-related bystander effect is an important role of carbon-ion induced lethal effect. (author)

  5. Effects of anisotropic fluences and angular depended spectra of beta-particles in the use of large area reference sources

    Calibrations of instrument efficiency of surface contamination meters are usually made with extended reference sources which are standardized in terms of 2π surface β-particle emission rates from the source surface including backscattered particles. Extended sources supplied from various metrology institutes or calibration laboratories, but the source-types such as structure, preparation method, backing and covering materials vary between manufacturers. In this work first we show how the calibration results are dependent on the source type. Second, in order to clarify the possible reason of such discrepancy, we examined the isotropy of β-particle fluences by the use of a proportional counter and also observed the angular dependence of β-particle spectra by the use of small plastic scintillation spectrometer, where the source mount can rotate relative to the detector window at various obliquities. The discrepancy in the instrument-calibration of surface contamination meters, which are mainly used under the conditions of large source-to-detector geometry, can be explained. - Highlights: ► We show how the calibration results are dependent on the source type. ► We examined the isotropy of β-particle fluences and observed the angular dependence. ► Discrepancy of instrument efficiencies using different type of sources is explained.

  6. Trapping in irradiated p-on-n silicon sensors at fluences anticipated at the HL-LHC outer tracker

    Adam, W. [Institut fur Hochenergiephysik der Osterreichischen Akademie der Wissenschaften (HEPHY), Vienna (Austria). et al.

    2015-05-08

    The degradation of signal in silicon sensors is studied under conditions expected at the CERN High-Luminosity LHC. 200μm thick n-type silicon sensors are irradiated with protons of different energies to fluences of up to 3 • 1015 neq/cm2. Pulsed red laser light with a wavelength of 672 nm is used to generate electron-hole pairs in the sensors. The induced signals are used to determine the charge collection efficiencies separately for electrons and holes drifting through the sensor. The effective trapping rates are extracted by comparing the results to simulation. The electric field is simulated using Synopsys device simulation assuming two effective defects. The generation and drift of charge carriers are simulated in an independent simulation based on PixelAV. The effective trapping rates are determined from the measured charge collection efficiencies and the simulated and measured time-resolved current pulses are compared. Furthermore, the effective trapping rates determined for both electrons and holes are about 50% smaller than those obtained using standard extrapolations of studies at low fluences and suggests an improved tracker performance over initial expectations.

  7. Calculus of the fluence and the absorbed dose by the different head tissues before photons of distinct energies

    Two models were used, in the first one the head was built with the scalp that includes the skin and the adipose tissue, the skull, the brain and the tumor, it is modeled as a sphere of 1 cm of radius that be places in the center of the head pattern. The spherical models of the scalp, the skull and the brain were built respectively with spheres of 8.5, 8 and 7 cm of radius. The tumor was irradiated with an unidirectional beam of photons, the calculated cases were photons of 60Co and monoenergetic photons beams of 6, 8, 10 and 15 MeV. For each case be calculated the total photons fluence to 5, 10 and 15 cm in air and to 20.5 cm that is the interface between the air and head. This calculus included values of photons fluence halfway the scalp, halfway the skull, halfway the brain and in the tumor center. Also is calculated the total absorbed dose by the scalp, the skull, the brain and the tumor. (author)

  8. A comparative study on efficacy of high and low fluence Q-switched Nd:YAG laser and glycolic acid peel in melasma

    Hemanta Kumar Kar

    2012-01-01

    Full Text Available Background: Melasma is acquired symmetric hypermelanosis characterized by light-to-deep brown pigmentation over cheeks, forehead, upper lip, and nose. Treatment of this condition is difficult and associated with high recurrence rates. With the advent of newer therapies, there is interest in the use of glycolic acid peels and Q-switched Nd:YAG laser (QSNYL in high and low fluence for this disorder. Aims: To compare the therapeutic efficacy of low fluence QSNYL, high fluence QSNYL, and glycolic acid peel in melasma in three study groups of 25 patients each. Methods: Seventy-five Indian patients diagnosed as melasma were included. These patients were randomly divided in three groups (Group A = 25 patients of melasma treated with low-fluence QSNYL at weekly intervals, Group B = 25 patients of melasma treated with glycolic acid peel at 2 weeks intervals, Group C = 25 patients of melasma treated with high-fluence QSNYL at 2 weeks intervals. Study period and follow-up period was of 12 weeks each. Out of the 75 patients included, 21 patients in Group A, 19 patients in Group B, and 20 patients in Group C completed the study. Response to treatment was assessed using melasma area and severity index score. Results: Significant improvement was recorded in all the three groups. The improvement was statistically highly significant in Group A as compared to Group C (P<0.005, significant in Group A as compared to Group B (P<0.05, and also in Group B when compared to Group C (P<0.05. Low-fluence QSNYL was associated with least side effects. Conclusions: This study shows the efficacy of low-fluence QSNYL and glycolic acid peel in melasma. These could be an effective treatment options compared to conventional methods for the treatment of melasma.

  9. Herpes simplex virus 2 infection impacts stress granule accumulation.

    Finnen, Renée L; Pangka, Kyle R; Banfield, Bruce W

    2012-08-01

    Interference with stress granule (SG) accumulation is gaining increased appreciation as a common strategy used by diverse viruses to facilitate their replication and to cope with translational arrest. Here, we examined the impact of infection by herpes simplex virus 2 (HSV-2) on SG accumulation by monitoring the localization of the SG components T cell internal antigen 1 (TIA-1), Ras-GTPase-activating SH3-domain-binding protein (G3BP), and poly(A)-binding protein (PABP). Our results indicate that SGs do not accumulate in HSV-2-infected cells and that HSV-2 can interfere with arsenite-induced SG accumulation early after infection. Surprisingly, SG accumulation was inhibited despite increased phosphorylation of eukaryotic translation initiation factor 2α (eIF2α), implying that HSV-2 encodes previously unrecognized activities designed to maintain translation initiation downstream of eIF2α. SG accumulation was not inhibited in HSV-2-infected cells treated with pateamine A, an inducer that works independently of eIF2α phosphorylation. The SGs that accumulated following pateamine A treatment of infected cells contained G3BP and PABP but were largely devoid of TIA-1. We also identified novel nuclear structures containing TIA-1 that form late in infection. These structures contain the RNA binding protein 68-kDa Src-associated in mitosis (Sam68) and were noticeably absent in infected cells treated with inhibitors of viral DNA replication, suggesting that they arise as a result of late events in the virus replicative cycle. PMID:22623775

  10. Accumulation of cobalt by cephalopods

    Accumulation of cobalt by cephalopod mollusca was investigated by radiotracer experiments and elemental analysis. In the radiotracer experiments, Octopus vulgaris took up cobalt-60 from seawater fairly well and the concentration of the nuclide in whole body attained about 150 times the level of seawater at 25th day at 200C. Among the tissues and organs measured, branchial heart which is the specific organ of cephalopods showed the highest affinity for the nuclide. The organ accumulated about 50% of the radioactivity in whole body in spite of its little mass as 0.2% of total body weight. On the other hand, more than 90% of the radioactivity taken up from food (soft parts of Gomphina melanaegis labelled with cobalt-60 previously in an aquarium) was accumulated in liver at 3rd day after the single administration and then the radioactivity in the liver seemed to be distributed to other organs and tissues. The characteristic elution profiles of cobalt-60 was observed for each of the organs and tissues in Sephadex gel-filtration experiment. It was confirmed by the gel-filtration that most of cobalt-60 in the branchial heart was combined with the constituents of low molecular weights. The average concentration of stable cobalt in muscle of several species of cephalopods was 5.3 +- 3.0 μg/kg wet and it was almost comparable to the fish muscle. On the basis of soft parts, concentration of the nuclide closed association among bivalve, gastropod and cephalopod except squid that gave lower values than the others. (author)

  11. Extracting the distribution of laser damage precursors on fused silica surfaces for 351 nm, 3 ns laser pulses at high fluences (20-150 J/cm2).

    Laurence, Ted A; Bude, Jeff D; Ly, Sonny; Shen, Nan; Feit, Michael D

    2012-05-01

    Surface laser damage limits the lifetime of optics for systems guiding high fluence pulses, particularly damage in silica optics used for inertial confinement fusion-class lasers (nanosecond-scale high energy pulses at 355 nm/3.5 eV). The density of damage precursors at low fluence has been measured using large beams (1-3 cm); higher fluences cannot be measured easily since the high density of resulting damage initiation sites results in clustering. We developed automated experiments and analysis that allow us to damage test thousands of sites with small beams (10-30 µm), and automatically image the test sites to determine if laser damage occurred. We developed an analysis method that provides a rigorous connection between these small beam damage test results of damage probability versus laser pulse energy and the large beam damage results of damage precursor densities versus fluence. We find that for uncoated and coated fused silica samples, the distribution of precursors nearly flattens at very high fluences, up to 150 J/cm2, providing important constraints on the physical distribution and nature of these precursors. PMID:22565775

  12. SU-E-T-261: Plan Quality Assurance of VMAT Using Fluence Images Reconstituted From Log-Files

    Purpose: A successful VMAT plan delivery includes precise modulations of dose rate, gantry rotational and multi-leaf collimator (MLC) shapes. One of the main problem in the plan quality assurance is dosimetric errors associated with leaf-positional errors are difficult to analyze because they vary with MU delivered and leaf number. In this study, we calculated integrated fluence error image (IFEI) from log-files and evaluated plan quality in the area of all and individual MLC leaves scanned. Methods: The log-file reported the expected and actual position for inner 20 MLC leaves and the dose fraction every 0.25 seconds during prostate VMAT on Elekta Synergy. These data were imported to in-house software that developed to calculate expected and actual fluence images from the difference of opposing leaf trajectories and dose fraction at each time. The IFEI was obtained by adding all of the absolute value of the difference between expected and actual fluence images corresponding. Results: In the area all MLC leaves scanned in the IFEI, the average and root mean square (rms) were 2.5 and 3.6 MU, the area of errors below 10, 5 and 3 MU were 98.5, 86.7 and 68.1 %, the 95 % of area was covered with less than error of 7.1 MU. In the area individual MLC leaves scanned in the IFEI, the average and rms value were 2.1 – 3.0 and 3.1 – 4.0 MU, the area of errors below 10, 5 and 3 MU were 97.6 – 99.5, 81.7 – 89.5 and 51.2 – 72.8 %, the 95 % of area was covered with less than error of 6.6 – 8.2 MU. Conclusion: The analysis of the IFEI reconstituted from log-file was provided detailed information about the delivery in the area of all and individual MLC leaves scanned

  13. Fluence map optimization (FMO) with dose-volume constraints in IMRT using the geometric distance sorting method

    Lan, Yihua; Li, Cunhua; Ren, Haozheng; Zhang, Yong; Min, Zhifang

    2012-10-01

    A new heuristic algorithm based on the so-called geometric distance sorting technique is proposed for solving the fluence map optimization with dose-volume constraints which is one of the most essential tasks for inverse planning in IMRT. The framework of the proposed method is basically an iterative process which begins with a simple linear constrained quadratic optimization model without considering any dose-volume constraints, and then the dose constraints for the voxels violating the dose-volume constraints are gradually added into the quadratic optimization model step by step until all the dose-volume constraints are satisfied. In each iteration step, an interior point method is adopted to solve each new linear constrained quadratic programming. For choosing the proper candidate voxels for the current dose constraint adding, a so-called geometric distance defined in the transformed standard quadratic form of the fluence map optimization model was used to guide the selection of the voxels. The new geometric distance sorting technique can mostly reduce the unexpected increase of the objective function value caused inevitably by the constraint adding. It can be regarded as an upgrading to the traditional dose sorting technique. The geometry explanation for the proposed method is also given and a proposition is proved to support our heuristic idea. In addition, a smart constraint adding/deleting strategy is designed to ensure a stable iteration convergence. The new algorithm is tested on four cases including head-neck, a prostate, a lung and an oropharyngeal, and compared with the algorithm based on the traditional dose sorting technique. Experimental results showed that the proposed method is more suitable for guiding the selection of new constraints than the traditional dose sorting method, especially for the cases whose target regions are in non-convex shapes. It is a more efficient optimization technique to some extent for choosing constraints than the dose

  14. Fluence map optimization (FMO) with dose–volume constraints in IMRT using the geometric distance sorting method

    A new heuristic algorithm based on the so-called geometric distance sorting technique is proposed for solving the fluence map optimization with dose–volume constraints which is one of the most essential tasks for inverse planning in IMRT. The framework of the proposed method is basically an iterative process which begins with a simple linear constrained quadratic optimization model without considering any dose–volume constraints, and then the dose constraints for the voxels violating the dose–volume constraints are gradually added into the quadratic optimization model step by step until all the dose–volume constraints are satisfied. In each iteration step, an interior point method is adopted to solve each new linear constrained quadratic programming. For choosing the proper candidate voxels for the current dose constraint adding, a so-called geometric distance defined in the transformed standard quadratic form of the fluence map optimization model was used to guide the selection of the voxels. The new geometric distance sorting technique can mostly reduce the unexpected increase of the objective function value caused inevitably by the constraint adding. It can be regarded as an upgrading to the traditional dose sorting technique. The geometry explanation for the proposed method is also given and a proposition is proved to support our heuristic idea. In addition, a smart constraint adding/deleting strategy is designed to ensure a stable iteration convergence. The new algorithm is tested on four cases including head–neck, a prostate, a lung and an oropharyngeal, and compared with the algorithm based on the traditional dose sorting technique. Experimental results showed that the proposed method is more suitable for guiding the selection of new constraints than the traditional dose sorting method, especially for the cases whose target regions are in non-convex shapes. It is a more efficient optimization technique to some extent for choosing constraints than

  15. Biota-Sediment Accumulation Factor Data

    U.S. Environmental Protection Agency — The Biota-Sediment Accumulation Factor contains approximately 20,000 biota-sediment accumulation factors (BSAFs) from 20 locations (mostly Superfund sites) for...

  16. Monitoring the source monitoring.

    Luna, Karlos; Martín-Luengo, Beatriz

    2013-11-01

    The hypothesis that the retrieval of correct source memory cues, those leading to a correct source attribution, increases confidence, whereas the retrieval of incorrect source memory cues, those leading to a source misattribution, decreases confidence was tested. Four predictions were derived from this hypothesis: (1) confidence should be higher for correct than incorrect source attribution except; (2) when no source cues are retrieved; (3) only the source misattributions inferred from the retrieval of incorrect source cues will be rated with low confidence; and (4) the number of source cues retrieved, either correct or incorrect, will affect the confidence in the source attributions. To test these predictions, participants read two narratives from two witnesses to a bank robbery, a customer and a teller. Then, participants completed a source monitoring test with four alternatives, customer, teller, both, or neither, and rated their confidence in their source attribution. Results supported the first three predictions, but they also suggested that the number of correct source monitoring cues retrieved did not play a role in the monitoring of the accuracy of the source attributions. Attributions made from the recovery of incorrect source cues could be tagged as dubious or uncertain, thus leading to lowered confidence irrespective of the number of incorrect source cues or whether another correct source cue was also recovered. This research has potential applications for eyewitness memory because it shows that confidence can be an indicator of the accuracy of a source attribution. PMID:23553316

  17. Research of Mosses Accumulation Properties Used for Assessment of Regional and Local Atmospheric Pollution

    Nadezhda K. Ryzhakova

    2014-10-01

    Full Text Available The monitoring of atmospheric heavy metal and other toxic element depositions by using widespread bryophytes as biomonitors has been widely used. Choosing most appropriate moss species in relation to their accumulation properties is the main goal of this research. The accumulation of heavy metals and other toxic elements by widespread mosses of midland have been studied. The research is focused on assessing accumulation properties of 4 species of terrestrial moss, 4 species of paludal moss and 2 species of epiphytic moss. The concentrations of 32 elements have been determined in moss samples by neutron activation analysis (NAA and atom emission spectrometry (AES. Interspecies and intraspecies comparison revealed significant differences in accumulation properties. The accumulation capacity of Dicranum polysetum was higher than other terrestrial mosses and Aulacomnium palustre had higher accumulation capacity than other paludal mosses. These moss species have been used for monitoring atmospheric pollutants in an immense territory, particularly for research of transboundary transfer of heavy metal pollution. The accumulation property of epiphytic moss was higher than others. The epiphytic moss could be found on the bark of old trees (aspens, poplars, birch that are of frequent occurrence in urban areas. Therefore, epiphytic moss can be used for monitoring atmospheric pollutants in an immense territory and for research of atmospheric pollution in industrial centers, inhabited locations as well as assessment of atmospheric contamination in local pollution source. DOI: http://dx.doi.org/10.5755/j01.erem.69.3.5566

  18. 47 CFR 32.3100 - Accumulated depreciation.

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Accumulated depreciation. 32.3100 Section 32... Accumulated depreciation. (a) This account shall include the accumulated depreciation associated with the... with depreciation amounts concurrently charged to Account 6561, Depreciation...

  19. Quantitative assessment of growing hair counts, thickness and colour during and after treatments with a low-fluence, home-device laser

    Thaysen-Petersen, D; Barbet-Pfeilsticker, M; Beerwerth, F;

    2015-01-01

    BACKGROUND: At-home laser and intense pulsed-light hair removal continues to grow in popularity and availability. A relatively limited body of evidence is available on the course of hair growth during and after low-fluence laser usage. OBJECTIVES: To assess growing hair counts, thickness and colour...... quantitatively during and after cessation of low-fluence laser treatment. METHODS: Thirty-six women with skin phototypes I-IV and light to dark-brown axillary hairs were included. Entire axillary regions were randomized to zero or eight self-administered weekly treatments with an 810-nm home-use laser at 5......%). After treatment cessation, hair growth gradually returned to baseline levels, and 3 months after the final treatment the count and thickness of actively growing hair exceeded pretreatment values by 29% and 7%, respectively (P ≤ 0·04). CONCLUSIONS: Sustained usage of low-fluence laser induced a stable...

  20. High fluence 1.05 μm performance tests using 20 ns shaped pulses on the Beamlet prototype laser

    Beamlet is a single beamline, nearly full scale physics prototype of the 192 beam Nd:Glass laser driver of the National Ignition Facility. It is used to demonstrate laser performance of the NIF multipass amplifier architecture. Initial system characterization tests have all been performed at pulse durations less than 10 ns. Pinhole closure and modulation at the end of long pulses are a significant concern for the operation of NIF. We recently demonstrated the generation, amplification and propagation of high energy pulses temporally shaped to mimic 20 ns long ignition pulse shapes at fluence levels exceeding the nominal NIF design requirements for Inertial Confinement Fusion by Indirect Drive. We also demonstrated the effectiveness of a new conical pinhole design used in the transport spatial filter to mitigate plasma closure effects and increase closure time to exceed the duration of the 20 ns long pulse

  1. Characterization of n-GaN dilute magnetic semiconductors by cobalt ions implantation at high-fluence

    Husnain, G.; Shu-De, Yao; Ahmad, Ishaq; Rafique, H. M.; Mahmood, Arshad

    2012-03-01

    In this study, we present the structural and magnetic characteristics of cobalt ions implantation at a high-fluence (5×1016 cm-2) into n-GaN epilayer of thickness about 1.6 μm. The n-GaN was grown on sapphire by metal organic chemical vapor deposition (MOCVD). Rutherford backscattering channeling was used for the structural study. After implantation, samples were annealed at 700, 800 and 900 °C by rapid thermal annealing in ambient N2. XRD measurements did not show any secondary phase or metal related-peaks. High resolution X-ray diffraction (HRXRD) was performed as well to characterize structures. Well-defined hysteresis loops were observed at 5 K and room temperature using alternating gradient magnetometer AGM and Superconducting Quantum Interference Device (SQUID) magnetometer. Temperature-dependent magnetization indicated magnetic moment at the lowest temperatures and retained magnetization up to 380 K for cobalt-ion-implanted samples.

  2. Determination of the fluence profile in three dimension for the thermal column of the TRIGA Mark III reactor

    In this work the results of the dosimetric properties of the lithium carbonate are presented (detecting), before the thermal neutrons. The process consists on irradiating samples of lithium carbonate in the installation of the thermal column of the TRIGA Mark III reactor, with a controlled period and with time intervals of 20 hours of irradiation. It is necessary to mention that the detectors were placed in different internal positions of the thermal column. With the purpose of being used these results for future studies, like it is the fluence profile in the thermal column. To use the BNCT technique (Boron Neutron Capture Therapy). Which is a binary technique that requires the simultaneous presence of a neutron flux with appropriate energy and a neutron captor (10B), those which interacting to attack to the tumor cells without producing significant damage to the tissues when both agents are separated. (Author)

  3. Feasibility study on using imaging plates to estimate thermal neutron fluence in neutron-gamma mixed fields

    In current radiotherapy, neutrons are produced in a photonuclear reaction when incident photon energy is higher than the threshold. In the present study, a method of discriminating the neutron component was investigated using an imaging plate (IP) in the neutron-gamma-ray mixed field. Two types of IP were used: a conventional IP for beta- and gamma rays, and an IP doped with Gd for detecting neutrons. IPs were irradiated in the mixed field, and the photo-stimulated luminescence (PSL) intensity of the thermal neutron component was discriminated using an expression proposed herein. The PSL intensity of the thermal neutron component was proportional to thermal neutron fluence. When additional irradiation of photons was added to constant neutron irradiation, the PSL intensity of the thermal neutron component was not affected. The uncertainty of PSL intensities was approximately 11.4 %. This method provides a simple and effective means of discriminating the neutron component in a mixed field. (authors)

  4. The morphology and structure of one-dimensional carbon-carbon composite under high-fluence ion irradiation

    Andrianova, N.N.; Borisov, A.M. [Institute of Nuclear Physics, Moscow State University, Leninsky Gori, 119991 Moscow (Russian Federation); Mashkova, E.S. [Institute of Nuclear Physics, Moscow State University, Leninsky Gori, 119991 Moscow (Russian Federation)], E-mail: es_mashkova@mail.ru; Virgiliev, Yu.S. [NIIgraphite, Electrodnaya 2, 111141 Moscow (Russian Federation)

    2009-08-15

    The temperature dependences of the ion-induced electron emission yield {gamma}(T), the crystal structure, and the morphology of a surface layer of the one-dimensional carbon fiber composite KUP-VM (1D) under high-fluence (10{sup 18}-10{sup 19} ion/cm{sup 2}) irradiation with 30 keV N{sub 2}{sup +} ions at normal incidence both perpendicular and parallel to the fiber directions have been studied. The target temperature has been varied during continuous irradiation from T = -180 to 400 deg. C. The surface analysis has been performed by the RHEED, SEM and RBS techniques. The surface microgeometry was studied using laser goniophotometry (LGP). It has been found that ion irradiation results in a loss of anisotropy of the surface layer structure because of amorphization at room temperature or recrystallization at a temperature higher than the ion-induced annealing temperature. The fiber morphology anisotropy remains under ion irradiation.

  5. The morphology and structure of one-dimensional carbon-carbon composite under high-fluence ion irradiation

    The temperature dependences of the ion-induced electron emission yield γ(T), the crystal structure, and the morphology of a surface layer of the one-dimensional carbon fiber composite KUP-VM (1D) under high-fluence (1018-1019 ion/cm2) irradiation with 30 keV N2+ ions at normal incidence both perpendicular and parallel to the fiber directions have been studied. The target temperature has been varied during continuous irradiation from T = -180 to 400 deg. C. The surface analysis has been performed by the RHEED, SEM and RBS techniques. The surface microgeometry was studied using laser goniophotometry (LGP). It has been found that ion irradiation results in a loss of anisotropy of the surface layer structure because of amorphization at room temperature or recrystallization at a temperature higher than the ion-induced annealing temperature. The fiber morphology anisotropy remains under ion irradiation.

  6. Structural properties of gold-silicon nanohybrids formed by femtosecond laser ablation in water at different fluences

    Ryabchikov, Y. V.; Popov, A. A.; Sentis, M.; Timoshenko, V. Y.; Kabashin, A. V.

    2016-03-01

    A gold target was ablated by femtosecond laser radiation in aqueous solutions of preliminarily prepared Si nanoparticles. The ablation process led to the formation of Au-based spherical colloids with the mean size around 5-10 nm and a weak abundance of larger species. Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray (EDX) analysis revealed the presence of Au and Si in colloid composition, while the stoichiometry of colloids did not depend on laser fluence during the fabrication experiments. The formation of Au-Si nanohybrid structure was explained by an effect of the interaction of laser-ablated Au nanoclusters with water-dispersed Si nanoparticles. The fabricated structures can be of importance for biomedical, catalysis, and photovoltaics applications.

  7. Fluence-to-dose conversion coefficients for muons and pions calculated based on ICRP publication 103 using the PHITS code

    The fluence to effective-dose and organ-absorbed-dose conversion coefficients for charged pions and muons were calculated based on the instructions given in ICRP Publication 103. For the calculation, the particle motions in the ICRP/ICRU adult reference computational phantoms were simulated using the PHITS code for four idealized irradiation geometries as well as those closely representing the geometrical simulations of cosmic-ray muon exposure. Cosmic-ray pion and muon dose rates over a wide altitude range were estimated using the calculated dose conversion coefficients. The results of the calculation indicate that the assumption of the isotropic irradiation geometry is suitable to be utilized in the dose estimations for cosmic-ray pions and muons. It is also found from the calculation that the introduction of ICRP103 gives little impact on the pion and muon dosimetries, since the radiation weighting factors assigned to those particles are maintained in the issue. (author)

  8. Novel treatment of Hori′s nevus: A combination of fractional nonablative 2,940-nm Er:YAG and low-fluence 1,064-nm Q-switched Nd:YAG laser

    Brian Wei Cheng Anthony Tian

    2015-01-01

    Full Text Available Objective: To demonstrate a combination laser therapy to treat Hori′s nevus. Design: A prospective study. Setting: A Singapore-based clinic. Participants: Five female patients, aged 30-46 years, with bilateral malar Hori′s nevus. Measurements: Photographs were taken before treatment and 1 month after laser treatment was completed. These were graded by three independent physicians. The patients were also asked to grade their treatment response subjectively. They were followed up for a total of 3 months after laser treatment to monitor recurrence. Materials and Methods: The fractional nonablative 2,940-nm Er:YAG laser with a fluence of 0.7 J/cm 2, spot size 12 mm, and frequency 15 Hz was used to perform a full-face single-pass treatment. Subsequently, a second pass and third pass over Hori′s nevi were done bilaterally till the clinical endpoint of skin whitening. The 1,064-nm Q-switched (QS Nd:YAG at a fluence of 2.0 J/cm 2 , frequency 2 Hz, and 4-mm spot size was used to deliver multiple passes over Hori′s nevus till erythema with mild petechiae appeared. We repeated the treatment once a week for 3 more consecutive weeks. Results: All five patients had above 80% improvement in their pigmentation and two (skin type III achieved complete 100% clearance. Based on the patients′ subjective assessments, all five of them expressed satisfaction and felt that their pigmentation had improved. There were no complications noted. Conclusion: The fractional nonablative 2940 nm Er:YAG laser and Q-switched 1064nm laser Nd:YAG combination is an effective and safe treatment for Hori′s nevus.

  9. Use of niobium for accurate relative fast neutron fluence measurements at the pressure vessel in a WWER-440 NPP

    The reaction 93Nb (n,n') /sup 93m/Nb, with low threshold energy (approximately 0.9 MeV) was used in a novel way to obtain both absolute and accurate, relative experimental estimates for the fast neutron (threshold) fluence at the inner wall of the pressure vessel (PV) in a WWER-440 type PWR reactor. Niobium was separated using chemical methods from steel samples containing 0.5...1% niobium, which had been scraped from the inner wall of the Loviisa NPP. Irradiated niobium foils from the surveillance chains (SC) were also treated in a similar way. Niobium from the liquid samples was then electro-deposited in very thin layers on copper discs. The amount of niobium deposited was determined by spectrophotometry and liquid scintillation measurements. The accuracy of the mass determination was further checked by an additional and independent method. The absolute activity of the niobium deposits was determined by measuring the 16.6 and 18.6 keV X-ray emission with a calibrated Si(Li) detector. The threshold flux PHI/sub T/ (> 0.9 MeV) was then obtained. The results indicate that the relative fluence estimates (PV/SC), which are sufficient for relating the measured embrittlement of the SC steel samples to the embrittlement of the PV, can be obtained with many times reduced in-accuracy (from tens of per cent to less than ten per cent) as compared to separate absolute estimates and estimate obtained by normalizing the calculated fluxes to conform with the measured results at the SC. (author)

  10. Characterization of n-GaN dilute magnetic semiconductors by cobalt ions implantation at high-fluence

    Husnain, G., E-mail: husnain78@gmail.com [State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Experimental Physics Labs, National Centre for Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Yao Shude [State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Ahmad, Ishaq [Experimental Physics Labs, National Centre for Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Rafique, H.M. [Department of Physics, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590 (Pakistan); Mahmood, Arshad [National Institute of Lasers and Optronics, P.O. Nilore, Islamabad (Pakistan)

    2012-03-15

    In this study, we present the structural and magnetic characteristics of cobalt ions implantation at a high-fluence (5 Multiplication-Sign 10{sup 16} cm{sup -2}) into n-GaN epilayer of thickness about 1.6 {mu}m. The n-GaN was grown on sapphire by metal organic chemical vapor deposition (MOCVD). Rutherford backscattering channeling was used for the structural study. After implantation, samples were annealed at 700, 800 and 900 Degree-Sign C by rapid thermal annealing in ambient N{sub 2}. XRD measurements did not show any secondary phase or metal related-peaks. High resolution X-ray diffraction (HRXRD) was performed as well to characterize structures. Well-defined hysteresis loops were observed at 5 K and room temperature using alternating gradient magnetometer AGM and Superconducting Quantum Interference Device (SQUID) magnetometer. Temperature-dependent magnetization indicated magnetic moment at the lowest temperatures and retained magnetization up to 380 K for cobalt-ion-implanted samples. - Highlights: Black-Right-Pointing-Pointer Experiment started with MOCVD grown semiconducting material GaN. Black-Right-Pointing-Pointer GaN was implanted with cobalt ions (Co{sup +}) of dose 5 Multiplication-Sign 10{sup 16} cm{sup -2} at room temperature. Black-Right-Pointing-Pointer Structural characterization was performed by RBS, XRD and HR-XRD. Black-Right-Pointing-Pointer Magnetic properties were observed by AGM and SQUID measurements. Black-Right-Pointing-Pointer High T{sub C} dilute magnetic semiconductors has been observed up to 380 K for cobalt implanted GaN at high-fluence (5 Multiplication-Sign 10{sup 16} cm{sup -2}).

  11. Reliable detection of fluence anomalies in EPID-based IMRT pretreatment quality assurance using pixel intensity deviations

    Purpose: This work uses repeat images of intensity modulated radiation therapy (IMRT) fields to quantify fluence anomalies (i.e., delivery errors) that can be reliably detected in electronic portal images used for IMRT pretreatment quality assurance. Methods: Repeat images of 11 clinical IMRT fields are acquired on a Varian Trilogy linear accelerator at energies of 6 MV and 18 MV. Acquired images are corrected for output variations and registered to minimize the impact of linear accelerator and electronic portal imaging device (EPID) positioning deviations. Detection studies are performed in which rectangular anomalies of various sizes are inserted into the images. The performance of detection strategies based on pixel intensity deviations (PIDs) and gamma indices is evaluated using receiver operating characteristic analysis. Results: Residual differences between registered images are due to interfraction positional deviations of jaws and multileaf collimator leaves, plus imager noise. Positional deviations produce large intensity differences that degrade anomaly detection. Gradient effects are suppressed in PIDs using gradient scaling. Background noise is suppressed using median filtering. In the majority of images, PID-based detection strategies can reliably detect fluence anomalies of ≥5% in ∼1 mm2 areas and ≥2% in ∼20 mm2 areas. Conclusions: The ability to detect small dose differences (≤2%) depends strongly on the level of background noise. This in turn depends on the accuracy of image registration, the quality of the reference image, and field properties. The longer term aim of this work is to develop accurate and reliable methods of detecting IMRT delivery errors and variations. The ability to resolve small anomalies will allow the accuracy of advanced treatment techniques, such as image guided, adaptive, and arc therapies, to be quantified.

  12. Analysis of short-range tracks and large track fluences in CR-39 PNTD using atomic force microscopy

    The standard method of analysis used with CR-39 plastic nuclear track detector (PNTD)- chemical etching followed by visible light microscope scanning-is limited to fluences less than 105 cm-2 and to particles of range ∼5 cm-2 the tracks begin to overlap, making analysis difficult. High-LET heavy nuclear recoil fragments often have ranges of 1-10 μm and bulk etch ≥8 μm results in over-etched tracks that are difficult to interpret. Both of these issues can be resolved by using a short etch (2-4 h 50 deg. C, 6.25 N NaOH) followed by atomic force microscopy (AFM) analysis. The dimensions of the post-etch tracks are typically a few hundred nanometers, a size within the resolution of an AFM. Because AFM provides a 3-D topographical map of the post-etch PNTD surface, there is more useful information contained in an AFM image than in a standard image of the post-etch CR-39 surface obtained using an optical microscope and CCD camera. We are developing a method based on AFM scanning, followed by matrix analysis (as opposed to image processing), which allows us to directly extract the relevant geometrical parameters of the tracks in an AFM image. This method is also amenable to automation. Progress in developing this method is illustrated with results from AFM analysis of CR-39 PNTD exposed to high fluences of energetic protons at the Loma Linda University Medical Center (LLUMC) Proton Therapy Facility.

  13. Markov models for accumulating mutations

    Beerenwinkel, Niko

    2007-01-01

    We introduce and analyze a waiting time model for the accumulation of genetic changes. The continuous time conjunctive Bayesian network is defined by a partially ordered set of mutations and by the rate of fixation of each mutation. The partial order encodes constraints on the order in which mutations can fixate in the population, shedding light on the mutational pathways underlying the evolutionary process. We study a censored version of the model and derive equations for an EM algorithm to perform maximum likelihood estimation of the model parameters. We also show how to select the maximum likelihood poset. The model is applied to genetic data from different cancers and from drug resistant HIV samples, indicating implications for diagnosis and treatment.

  14. Chip integrated fuel cell accumulator

    Frank, M.; Erdler, G.; Frerichs, H.-P.; Müller, C.; Reinecke, H.

    A unique new design of a chip integrated fuel cell accumulator is presented. The system combines an electrolyser and a self-breathing polymer electrolyte membrane (PEM) fuel cell with integrated palladium hydrogen storage on a silicon substrate. Outstanding advantages of this assembly are the fuel cell with integrated hydrogen storage, the possibility of refuelling it by electrolysis and the opportunity of simply refilling the electrolyte by adding water. By applying an electrical current, wiring the palladium hydrogen storage as cathode and the counter-electrode as anode, the electrolyser produces hydrogen at the palladium surface and oxygen at the electrolyser cell anode. The generated hydrogen is absorbed by the palladium electrode and the hydrogen storage is refilled consequently enabling the fuel cell to function.

  15. Chip integrated fuel cell accumulator

    Frank, M.; Mueller, C.; Reinecke, H. [Laboratory for Process Technology, IMTEK-Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg (Germany); Erdler, G.; Frerichs, H.-P. [Micronas GmbH, Hans-Bunte-Strasse 19, Freiburg (Germany)

    2008-07-01

    A unique new design of a chip integrated fuel cell accumulator is presented. The system combines an electrolyser and a self-breathing polymer electrolyte membrane (PEM) fuel cell with integrated palladium hydrogen storage on a silicon substrate. Outstanding advantages of this assembly are the fuel cell with integrated hydrogen storage, the possibility of refuelling it by electrolysis and the opportunity of simply refilling the electrolyte by adding water. By applying an electrical current, wiring the palladium hydrogen storage as cathode and the counter-electrode as anode, the electrolyser produces hydrogen at the palladium surface and oxygen at the electrolyser cell anode. The generated hydrogen is absorbed by the palladium electrode and the hydrogen storage is refilled consequently enabling the fuel cell to function. (author)

  16. Electron-Positron Accumulator (EPA)

    Photographic Service

    1986-01-01

    After acceleration in the low-current linac LIL-W, the electrons and positrons are accumulated in EPA to obtain a sufficient intensity and a suitable time-structure, before being passed on to the PS for further acceleration to 3.5 GeV. Electrons circulate from right to left, positrons in the other direction. Dipole bending magnets are red, focusing quadrupoles blue, sextupoles for chromaticity-control orange. The vertical tube at the left of the picture belongs to an optical transport system carrying the synchrotron radiation to detectors for beam size measurement. Construction of EPA was completed in spring 1986. LIL-W and EPA were conceived for an energy of 600 MeV, but operation was limited to 500 MeV.

  17. Does the fluence map editing in electronic tissue compensator improve dose homogeneity in bilateral field plan of head and neck patients?

    Kinhikar Rajesh

    2008-01-01

    Full Text Available The purpose of this study was to evaluate the effect of fluence map editing in electronic tissue compensator (ETC on the dose homogeneity for head and neck cancer patients. Treatment planning using 6-MV X-rays and bilateral field arrangement employing ETC was carried out on the computed tomography (CT datasets of 20 patients with head and neck cancer. All the patients were planned in Varian Eclipse three-dimensional treatment planning system (3DTPS with dynamic multileaf collimator (DMLC. The treatment plans, with and without fluence editing, was compared and the effect of pre-editing and post-editing the fluence maps in the treatment field was evaluated. The skin dose was measured with thermoluminescent dosimeters (TLDs and was compared with the skin dose estimated by TPS. The mean percentage volume of the tissue receiving at least 107% of the prescription dose was 5.4 (range 1.5-10; SD 2.4. Post-editing fluence map showed that the mean percentage volume of the tissue receiving at least 107% of the prescription dose was 0.47 (range 0.1-0.9; SD 0.3. The mean skin dose measured with TLD was found to be 74% (range 71-80% of the prescribed dose while the TPS showed the mean skin dose as 85% (range 80-90%. The TPS overestimated the skin dose by 11%. Fluence map editing thus proved to be a potential tool for improving dose homogeneity in head and neck cancer patients planned with ETC, thus reducing the hot spots in the treatment region as well. The treatment with ETC is feasible with DMLC and does not take any additional time for setup or delivery. The method used to edit the fluence maps is simple and time efficient. Manual control over a plan is essential to create the best treatment plan possible.

  18. Verification of TG-61 dose for synchrotron-produced monochromatic x-ray beams using fluence-normalized MCNP5 calculations

    Purpose: Ion chamber dosimetry is being used to calibrate dose for cell irradiations designed to investigate photoactivated Auger electron therapy at the Louisiana State University Center for Advanced Microstructures and Devices (CAMD) synchrotron facility. This study performed a dosimetry intercomparison for synchrotron-produced monochromatic x-ray beams at 25 and 35 keV. Ion chamber depth-dose measurements in a polymethylmethacrylate (PMMA) phantom were compared with the product of MCNP5 Monte Carlo calculations of dose per fluence and measured incident fluence. Methods: Monochromatic beams of 25 and 35 keV were generated on the tomography beamline at CAMD. A cylindrical, air-equivalent ion chamber was used to measure the ionization created in a 10 × 10 × 10-cm3 PMMA phantom for depths from 0.6 to 7.7 cm. The American Association of Physicists in Medicine TG-61 protocol was applied to convert measured ionization into dose. Photon fluence was determined using a NaI detector to make scattering measurements of the beam from a thin polyethylene target at angles 30°–60°. Differential Compton and Rayleigh scattering cross sections obtained from xraylib, an ANSI C library for x-ray-matter interactions, were applied to derive the incident fluence. MCNP5 simulations of the irradiation geometry provided the dose deposition per photon fluence as a function of depth in the phantom. Results: At 25 keV the fluence-normalized MCNP5 dose overestimated the ion-chamber measured dose by an average of 7.2 ± 3.0%–2.1 ± 3.0% for PMMA depths from 0.6 to 7.7 cm, respectively. At 35 keV the fluence-normalized MCNP5 dose underestimated the ion-chamber measured dose by an average of 1.0 ± 3.4%–2.5 ± 3.4%, respectively. Conclusions: These results showed that TG-61 ion chamber dosimetry, used to calibrate dose output for cell irradiations, agreed with fluence-normalized MCNP5 calculations to within approximately 7% and 3% at 25 and 35 keV, respectively.

  19. Guidelines for Waste Accumulation Areas (WAAs)

    The purpose of this document is to set conditions for establishing and maintaining areas for the accumulation of hazardous waste at LBL. Areas designed for accumulation of these wastes in quantities greater than 100 kg (220 lb) per month of solid waste or 55 gallons per month of liquid waste are called Waste Accumulation Areas (WAAs). Areas designed for accumulation of wastes in smaller amounts are called Satellite Accumulation Areas (SAAs). This document provides guidelines for employee and organizational responsibilities for WAAs; constructing a WAA; storing waste in a WAA; operating and maintaining a WAA, and responding to spills in a WAA. 4 figs

  20. Guidelines for Waste Accumulation Areas (WAAs)

    1991-07-01

    The purpose of this document is to set conditions for establishing and maintaining areas for the accumulation of hazardous waste at LBL. Areas designed for accumulation of these wastes in quantities greater than 100 kg (220 lb) per month of solid waste or 55 gallons per month of liquid waste are called Waste Accumulation Areas (WAAs). Areas designed for accumulation of wastes in smaller amounts are called Satellite Accumulation Areas (SAAs). This document provides guidelines for employee and organizational responsibilities for WAAs; constructing a WAA; storing waste in a WAA; operating and maintaining a WAA, and responding to spills in a WAA. 4 figs.

  1. Radionuclide accumulation peculiarities demonstrated by vegetable varieties

    This study focused on ecological and genetic aspects of radionuclide accumulation demonstrated by a number of vegetable varieties. The researches resulted in determining the cabbage varieties which were characterised by the minimal level of radionuclide accumulation. It was shown that the above varieties manifested the relation between radionuclide accumulation and morphobiological characteristics such as vegetation period duration and yield criteria. The study specified the genotypes with high ecological stability as regards to radionuclide accumulation: 'Beloruskaya 85' cabbage and 'Dokhodny' tomato showed the best response to Cs 137, while 'Beloruskaya 85', 'Rusinovka', 'Amager 611' cabbage varieties and 'Sprint' tomato showed the minimal level of Sr 90 accumulation. (authors)

  2. Automatic control and monitoring of the MIT fission converter beam

    An automated control and monitoring system for the new MIT high intensity epithermal neutron irradiation facility has been designed and constructed. The neutron beam is monitored with fission counters located at the periphery of the beam near the patient position. Control of the beam is accomplished with redundant Programmable Logic Controllers (PLCs). These industrial controllers open and close the three shutters of the Fission Converter Beam. The control system uses a series of robust components to assure that the prescribed fluence is delivered. This paper discusses the design and implementation of this system. (author)

  3. Damage accumulation in ceramics during ion implantation

    The damage structures of α-Al2O3 and α-SiC were examined as functions of ion implantation parameters using Rutherford backscattering-channeling, analytical electron microscopy, and Raman spectroscopy. Low temperatures or high fluences of cations favor formation of the amorphous state. At 3000K, mass of the bombarding species has only a small effect on residual damage, but certain ion species appear to stabilize the damage microstructure and increase the rate of approach to the amorphous state. The type of chemical bonding present in the host lattice is an important factor in determining the residual damage state

  4. Radiogenic gas accumulation in TRU waste storage drums

    A field experiment was conducted over a four-year time span to determine the effect of high-activity transuranic (TRU) waste on the atmosphere within TRU waste storage drums typical of those generated in Savannah River Plant operation. Routine gas composition analyses showed that a significant amount of hydrogen can accumulate in drums that contain high alpha activity, and that flammable gas mixtures could form in such drums in spite of the radiolytic consumption of oxygen. According to this study, gas pressure accumulation does not pose a threat to the integrity of the TRU waste containers that are now being stored at the Savannah River Plant. Therefore, the 20-year storage criterion is still viable. However, the continued avoidance of a perfectly gas-tight drum seal (e.g., epoxy, metal welding) is recommended. The test drums will continue to be monitored

  5. Accumulation of polychlorinated biphenyls from contaminated sediment by Atlantic cod (Gadus morhua): direct accumulation from resuspended sediment and dietary accumulation via the polychaete Nereis virens.

    Ruus, Anders; Daae, Ingrid Aarre; Hylland, Ketil

    2012-11-01

    Bioaccumulation of sediment-associated polychlorinated biphenyls (PCBs) was examined in Atlantic cod (Gadus morhua) through direct diffusion from the sediment (via the water phase) and through the food chain (dietary exposure). To facilitate direct accumulation from the sediment, it was continuously resuspended. To study the dietary bioaccumulation of PCBs, cod were fed benthic polychaetes (Nereis virens) previously exposed to test sediments, which were naturally polluted sediments from the inner Oslofjord (Norway). Both exposure experiments had a duration of 129 d. Furthermore, the role of sediments as a source of PCBs accumulated in Oslofjord cod was elucidated, using results from environmental monitoring as a reference. Generally, the results suggest that the contaminated sediments of the inner Oslofjord are an important source of legacy PCBs for accumulation in resident cod, although additional contributions may also be important. Crude estimates of assimilation efficiency of ingested PCBs (through diet) were found to be 30 to 50%; the highest was for the lower chlorinated congeners (PCB-28 and -52). Challenges for applying trophic magnification factors for determining biomagnification in laboratory experiments, in terms of preventive environmental safety, are indicated. The results provide useful information for parameterization of models describing the behavior of hydrophobic persistent contaminants in the foodweb of the Oslofjord and elsewhere. PMID:22865726

  6. Online Data Conversion for the LHCb Active Radiation Monitor System (ARMS)

    Farrugia, Julia

    2015-01-01

    Active radiation monitors are distributed in and around the LHCb experiment in order to monitor the evolution of radiation dose and 1 MeV equivalent neutron fluence. The active monitors are connected to an online network and their raw voltage measurement can be read out via WinCC panels. However, the raw voltage measurements must be corrected before conversion into correct dose or fluence. Previous work by [1] included a signal correction algorithm that corrects the values offline. The aim of this work is to understand how the signal correction algorithm works, archive previously corrected values into a new database system that will be integrated to a WinCC graphical interface and modify the algorithm so that it may process new values online while using less time and computing resources.

  7. Caffeoylquinic Acids Generated In Vitro in a High-Anthocyanin-Accumulating Sweet potato Cell Line

    Izabela Konczak; Shigenori Okuno; Makoto Yoshimoto; Osamu Yamakawa

    2004-01-01

    Accumulation of phenolic compounds has been monitored in a suspension culture of anthocyanin-accumulating sweet potato cell line grown under the conditions of modified Murashige and Skoog high-anthocyanin production medium (APM) over a period of 24 days. Tissue samples extracted with 15% acetic acid were analysed using HPLC at a detection wavelength of 326 nm. Among others, the following derivatives of caffeoylquinic acids were detected: 4,5-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid, 3...

  8. Quantum gravity and inventory accumulation

    Sheffield, Scott

    2011-01-01

    We begin by studying inventory accumulation at a LIFO (last-in-first-out) retailer with two products. In the simplest version, the following occur with equal probability at each time step: first product ordered, first product produced, second product ordered, second product produced. The inventory thus evolves as a simple random walk on Z^2. In more interesting versions, a p fraction of customers orders the "freshest available" product regardless of type. We show that the corresponding random walks scale to Brownian motions with diffusion matrices depending on p. We then turn our attention to the critical Fortuin-Kastelyn random planar map model, which gives, for each q>0, a probability measure on random (discretized) two-dimensional surfaces decorated by loops, related to the q-state Potts model. A longstanding open problem is to show that as the discretization gets finer, the surfaces converge in law to a limiting (loop-decorated) random surface. The limit is expected to be a Liouville quantum gravity surfa...

  9. Environmental parasitology: Parasites as accumulation bioindicators in the marine environment

    Nachev, Milen; Sures, Bernd

    2016-07-01

    Parasites can be used as effective monitoring tools in environmental impact studies as they are able to accumulate certain pollutants (e.g. metals) at levels much higher than those of their ambient environment and of free-living sentinels. Thus, they provide valuable information not only about the chemical conditions of their and their hosts' environment but also deliver insights into the biological availability of allochthonous substances. While a large number of different freshwater parasites (mainly acanthocephalans and cestodes) were investigated in terms of pollutant bioaccumulation, studies based on marine host-parasites systems remain scarce. However, available data show that different marine parasite taxa such as nematodes, cestodes and acanthocephalans exhibit also an excellent metal accumulation capacity. The biological availability of metals and their uptake routes in marine biota and parasites differ from those of freshwater organisms. We assume that a large part of metals and other pollutants are also taken up via the digestive system of the host. Therefore, in addition to environmental conditions the physiology of the host also plays an important role for the accumulation process. Additionally, we highlight some advantages in using parasites as accumulation indicators in marine ecosystems. As parasites occur ubiquitously in marine food webs, the monitoring of metals in their tissues can deliver information about the spatial and trophic distribution of pollutants. Accordingly, parasites as indicators offer an ecological assessment on a broader scale, in contrast to established free-living marine indicators, which are mostly benthic invertebrates and therefore limited in habitat distribution. Globally distributed parasite taxa, which are highly abundant in a large number of host species, are suggested as worldwide applicable sentinels.

  10. Structure and morphologies of ZnO nanoparticles synthesized by pulsed laser ablation in liquid: Effects of temperature and energy fluence

    Zinc oxide nanoparticles were prepared by pulsed laser ablation of a zinc metal target at different water temperatures (room temperature, 50, 70 and 90 °C). Ablation was carried out using 532 nm output from a pulsed (10 ns, 10 Hz) Nd:YAG laser at three different laser fluence. Analysis of the morphology, crystalline phase, elemental composition, optical and luminescent properties were done using Transmission Electron Microscopy (TEM), X-Ray Photoelectron Spectroscopy (XPS), UV–visible absorption spectroscopy and photoluminescence spectroscopy. TEM analysis showed that a change in temperature resulted in ZnO and Zn(OH)2 nanoparticles with different sizes and morphologies. XPS results confirmed the compositions and chemical states of these nanoparticles. These zinc nanomaterials showed emission in the ultraviolet (UV) and blue regions. The results of this work demonstrated that by varying the liquid medium temperature, the structure, composition, morphology and optical properties of the nanomaterials could be modified during pulsed laser ablation in liquid. - Graphical abstract: Display Omitted - Highlights: • Zinc nanomaterial colloids were synthesized by PLAL. • Effects of laser fluence and the distilled water temperature were analyzed. • The final structure varied with the distilled water temperature and laser fluence. • The morphology was dependent on the distilled water temperature and laser fluence. • Zinc nanocolloids showed emission in the UV and blue region

  11. Measurements of thermal neutron fluence proton therapy for head and neck; Medidas de la fluencia de neutrones termicos en protonterapia de cabeza y cuello

    Lagares, J. I.; Sansaloni, F.; Terron, J. A.; Muniz, J. L.; Exposito, M. r.; Nieto-Camero, J.J.; Korf, A.; Arce, P.; Nunez, L.; Loubser, M.; Sanchez-Doblado, F.

    2011-07-01

    We present an estimate of the distribution of thermal neutron fluence proton therapy for head and neck using an anthropomorphic phantom called NORMA. It also represents a small part within a larger project which aims to develop a risk prediction model due to neutron radiation generated indirectly in radiotherapy.

  12. Structure and morphologies of ZnO nanoparticles synthesized by pulsed laser ablation in liquid: Effects of temperature and energy fluence

    Guillén, G. García; Palma, M.I. Mendivil [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66455 (Mexico); Krishnan, B. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66455 (Mexico); Universidad Autónoma de Nuevo León – Centro de Innovación, Investigación y Desarrollo de Ingeniería y Tecnología, Apodaca, Nuevo León 66600 (Mexico); Avellaneda, D.; Castillo, G.A.; Roy, T.K. Das [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66455 (Mexico); and others

    2015-07-15

    Zinc oxide nanoparticles were prepared by pulsed laser ablation of a zinc metal target at different water temperatures (room temperature, 50, 70 and 90 °C). Ablation was carried out using 532 nm output from a pulsed (10 ns, 10 Hz) Nd:YAG laser at three different laser fluence. Analysis of the morphology, crystalline phase, elemental composition, optical and luminescent properties were done using Transmission Electron Microscopy (TEM), X-Ray Photoelectron Spectroscopy (XPS), UV–visible absorption spectroscopy and photoluminescence spectroscopy. TEM analysis showed that a change in temperature resulted in ZnO and Zn(OH){sub 2} nanoparticles with different sizes and morphologies. XPS results confirmed the compositions and chemical states of these nanoparticles. These zinc nanomaterials showed emission in the ultraviolet (UV) and blue regions. The results of this work demonstrated that by varying the liquid medium temperature, the structure, composition, morphology and optical properties of the nanomaterials could be modified during pulsed laser ablation in liquid. - Graphical abstract: Display Omitted - Highlights: • Zinc nanomaterial colloids were synthesized by PLAL. • Effects of laser fluence and the distilled water temperature were analyzed. • The final structure varied with the distilled water temperature and laser fluence. • The morphology was dependent on the distilled water temperature and laser fluence. • Zinc nanocolloids showed emission in the UV and blue region.

  13. Size properties of colloidal nanoparticles produced by nanosecond pulsed laser ablation and studying the effects of liquid medium and laser fluence

    Mahdieh, Mohammad Hossein, E-mail: mahdm@iust.ac.ir; Fattahi, Behzad

    2015-02-28

    Highlights: • Colloidal aluminum- and titanium-based nanoparticles fabricated by laser ablation. • Various liquid environments and laser fluences were applied as variable parameters. • Physical characteristics of liquid medium influence ablation process and nanoparticle formation. • Size properties of prepared nanoparticles depend on liquid medium and laser fluence. • Ablation of both metals in ethanol results in nanoparticles with smaller size. - Abstract: In this paper, pulsed laser ablation method was used for synthesis of colloidal nanoparticles of aluminum and titanium targets in distilled water, ethanol, and acetone as liquid environments. Ultraviolet–visible (UV–vis) absorption spectrophotometer and scanning electron microscope (SEM) were used for characterization of produced nanoparticles. Using image processing technique and analyzing the SEM images, nanoparticles’ mean size and size distribution were achieved. The results show that liquid medium has strong effect on size properties of produced nanoparticles. From the results, it was found that ablation of both metal targets in ethanol medium leads to formation of smaller size nanoparticles with narrower size distributions. The influence of laser fluence was also investigated. According to the results, higher laser fluence produces larger mean size nanoparticles with broader size distribution.

  14. Size properties of colloidal nanoparticles produced by nanosecond pulsed laser ablation and studying the effects of liquid medium and laser fluence

    Highlights: • Colloidal aluminum- and titanium-based nanoparticles fabricated by laser ablation. • Various liquid environments and laser fluences were applied as variable parameters. • Physical characteristics of liquid medium influence ablation process and nanoparticle formation. • Size properties of prepared nanoparticles depend on liquid medium and laser fluence. • Ablation of both metals in ethanol results in nanoparticles with smaller size. - Abstract: In this paper, pulsed laser ablation method was used for synthesis of colloidal nanoparticles of aluminum and titanium targets in distilled water, ethanol, and acetone as liquid environments. Ultraviolet–visible (UV–vis) absorption spectrophotometer and scanning electron microscope (SEM) were used for characterization of produced nanoparticles. Using image processing technique and analyzing the SEM images, nanoparticles’ mean size and size distribution were achieved. The results show that liquid medium has strong effect on size properties of produced nanoparticles. From the results, it was found that ablation of both metal targets in ethanol medium leads to formation of smaller size nanoparticles with narrower size distributions. The influence of laser fluence was also investigated. According to the results, higher laser fluence produces larger mean size nanoparticles with broader size distribution

  15. Comparison of prophylactic higher fluence corneal cross-linking to control, in myopic LASIK, one year results

    Kanellopoulos AJ

    2014-11-01

    Full Text Available Anastasios John Kanellopoulos,1,2 George Asimellis,1 Costas Karabatsas1 1LaserVision.gr Clinical and Research Eye Institute, Athens, Greece; 2New York University Medical School, New York, NY, USA Purpose: To compare 1-year results: safety, efficacy, refractive and keratometric stability, of femtosecond myopic laser-assisted in situ keratomileusis (LASIK with and without concurrent prophylactic high-fluence cross-linking (CXL (LASIK-CXL.Methods: We studied a total of 155 consecutive eyes planned for LASIK myopic correction. Group A represented 73 eyes that were treated additionally with concurrent prophylactic high-fluence CXL; group B included 82 eyes subjected to the stand-alone LASIK procedure. The following parameters were evaluated preoperatively and up to 1-year postoperatively: manifest refractive spherical equivalent (MRSE, refractive astigmatism, visual acuity, corneal keratometry, and endothelial cell counts. We plotted keratometry measurements pre-operatively and its change in the early, interim and later post-operative time for the two groups, as a means of keratometric stability comparison.Results: Group A (LASIK-CXL had an average postoperative MRSE of -0.23, -0.19, and -0.19 D for the 3-, 6-, and 12-month period, respectively, compared to -6.58±1.98 D preoperatively. Flat keratometry was 37.69, 37.66, and 37.67 D, compared to 43.94 D preoperatively, and steep keratometry was 38.35, 38.36, and 38.37 D, compared to 45.17 D preoperatively. The predictability of Manifest Refraction Spherical Equivalent (MRSE correction showed a correlation coefficient of 0.979. Group B (stand-alone LASIK had an average postoperative MRSE of -0.23, -0.20, and -0.27 D for the 3-, 6-, and 12-month period, respectively, compared with -5.14±2.34 D preoperatively. Flat keratometry was 37.65, 37.89, and 38.02 D, compared with 43.15 D preoperatively, and steep keratometry was 38.32, 38.57, and 38.66 D, compared with 44.07 D preoperatively

  16. Test measurements on a secco white-lead containing model samples to assess the effects of exposure to low-fluence UV laser radiation

    Raimondi, Valentina, E-mail: v.raimondi@ifac.cnr.it [‘Nello Carrara’ Applied Physics Institute - National Research Council of Italy (CNR-IFAC), Firenze (Italy); Andreotti, Alessia; Colombini, Maria Perla [Chemistry and Industrial Chemistry Department (DCCI) - University of Pisa, Pisa (Italy); Cucci, Costanza [‘Nello Carrara’ Applied Physics Institute - National Research Council of Italy (CNR-IFAC), Firenze (Italy); Cuzman, Oana [Institute for the Conservation and Promotion of Cultural Heritage - National Research Council (CNR-ICVBC), Firenze (Italy); Galeotti, Monica [Opificio delle Pietre Dure (OPD), Firenze (Italy); Lognoli, David; Palombi, Lorenzo; Picollo, Marcello [‘Nello Carrara’ Applied Physics Institute - National Research Council of Italy (CNR-IFAC), Firenze (Italy); Tiano, Piero [Institute for the Conservation and Promotion of Cultural Heritage - National Research Council (CNR-ICVBC), Firenze (Italy)

    2015-05-15

    Highlights: • A set of a secco model samples was prepared using white lead and four different organic binders (animal glue and whole egg, whole egg, skimmed milk, egg-oil tempera). • The samples were irradiated with low-fluence UV laser pulses (0.1–1 mJ/cm{sup 2}). • The effects of laser irradiation were analysed by using different techniques. • The analysis did not point out changes due to low-fluence laser irradiation. • High fluence (88 mJ/cm{sup 2}) laser radiation instead yielded a chromatic change ascribed to the inorganic component. - Abstract: Laser-induced fluorescence technique is widely used for diagnostic purposes in several applications and its use could be of advantage for non-invasive on-site characterisation of pigments or other compounds in wall paintings. However, it is well known that long-time exposure to UV and VIS radiation can cause damage to wall paintings. Several studies have investigated the effects of lighting, e.g., in museums: however, the effects of low-fluence laser radiation have not been studied much so far. This paper investigates the effects of UV laser radiation using fluences in the range of 0.1 mJ/cm{sup 2}–1 mJ/cm{sup 2} on a set of a secco model samples prepared with lead white and different type of binders (animal glue and whole egg, whole egg, skimmed milk, egg-oil tempera). The samples were irradiated using a Nd:YAG laser (emission wavelength at 355 nm; pulse width: 5 ns) by applying laser fluences between 0.1 mJ/cm{sup 2} and 1 mJ/cm{sup 2} and a number of laser pulses between 1 and 500. The samples were characterised before and after laser irradiation by using several techniques (colorimetry, optical microscopy, fibre optical reflectance spectroscopy, FT-IR spectroscopy Attenuated Total Reflectance microscopy and gas chromatography/mass spectrometry), to detect variations in the morphological and physico-chemical properties. The results did not point out significant changes in the sample properties after

  17. Test measurements on a secco white-lead containing model samples to assess the effects of exposure to low-fluence UV laser radiation

    Highlights: • A set of a secco model samples was prepared using white lead and four different organic binders (animal glue and whole egg, whole egg, skimmed milk, egg-oil tempera). • The samples were irradiated with low-fluence UV laser pulses (0.1–1 mJ/cm2). • The effects of laser irradiation were analysed by using different techniques. • The analysis did not point out changes due to low-fluence laser irradiation. • High fluence (88 mJ/cm2) laser radiation instead yielded a chromatic change ascribed to the inorganic component. - Abstract: Laser-induced fluorescence technique is widely used for diagnostic purposes in several applications and its use could be of advantage for non-invasive on-site characterisation of pigments or other compounds in wall paintings. However, it is well known that long-time exposure to UV and VIS radiation can cause damage to wall paintings. Several studies have investigated the effects of lighting, e.g., in museums: however, the effects of low-fluence laser radiation have not been studied much so far. This paper investigates the effects of UV laser radiation using fluences in the range of 0.1 mJ/cm2–1 mJ/cm2 on a set of a secco model samples prepared with lead white and different type of binders (animal glue and whole egg, whole egg, skimmed milk, egg-oil tempera). The samples were irradiated using a Nd:YAG laser (emission wavelength at 355 nm; pulse width: 5 ns) by applying laser fluences between 0.1 mJ/cm2 and 1 mJ/cm2 and a number of laser pulses between 1 and 500. The samples were characterised before and after laser irradiation by using several techniques (colorimetry, optical microscopy, fibre optical reflectance spectroscopy, FT-IR spectroscopy Attenuated Total Reflectance microscopy and gas chromatography/mass spectrometry), to detect variations in the morphological and physico-chemical properties. The results did not point out significant changes in the sample properties after irradiation in the proposed range of

  18. Risk monitors

    The aim of the presentation is to gain an understanding of the following: The relationship between the PSA and a safety monitor; the functions performed by safety monitor; typical operational specification; modeling requirements

  19. Biochemical diagnosis of mucopolysaccharidoses by estimation of intracellular 35S-sulfate accumulation

    The investigation of 35S-sulfate accumulation and of 35SO4-labelled glycosaminoglucane molecules (chase-experiments) in cultured cells was used in post- and prenatal diagnosis of mucopolysaccharidosis (MPS). Cell lines which accumulate 35S-sulfate can be differentiated by means of cross correction or measurement of enzyme activity. 34 patients with the MPS type I, II, III A, III B and VI, respectively, were diagnosed in this way. Four pregnancies at risk for MPS were prenatally monitored by the sulfate accumulation in cultured amniotic fluid cells. One fetus suffering from MPS II was found. (author)

  20. Neutron flux calculation and fluence in the encircling of the core and vessel of a reactor BWR

    One of the main objectives related to the safety of any nuclear power plant, including the nuclear power plant of Laguna Verde is to ensure the structural integrity of reactor pressure vessel. To identify and quantify the damage caused by neutron irradiation in the vessel of any nuclear reactor, it is necessary to know both the neutron flux and the neutron fluence that the vessel has been receiving during its operation lifetime, and that the damage observed by mechanical testing are products of microstructural effects induced by neutron irradiation; therefore, it is important the study and prediction of the neutron flux in order to have a better understanding of the damage that these materials are receiving. The calculation here described uses the DORT code, which solves the neutron transport equation in discrete ordinates in two dimensions (x-y, r-θ and r-z), according to a regulatory guide, it should make an approximation of the neutron flux in three dimensions by the so called synthesis method. It is called in that way because it achieves a representation of 3 Dimensional neutron flux combining or summarizing the fluxes calculated by DORT r-θ, r-z and r. This work presents the application of synthesis method, according to Regulatory Guide 1190, to determine the 3 Dimensional fluxes in internal BWR reactor using three different spatial meshes. The results of the neutron flux and fluence, using three different meshes in the directions r, θ and z were compared with results reported in the literature obtaining a difference not larger than 9.61%, neutron flux reached its maximum, 1.58 E + 12 n/cm2s, at a height H 4 (239.07 cm) and angle 32.236o in the core shroud and 4.00 E + 09 n/cm2s at a height H 4 and angle 35.27o in the inner wall of the reactor vessel, positions that are consistent to within ±10% over the ones reported in the literature. (Author)