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Sample records for burnable neutron absorber

  1. ATR LEU Monolithic Foil-Type Fuel with Integral Cladding Burnable AbsorberNeutronics Performance Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Gray Chang

    2012-03-01

    The Advanced Test Reactor (ATR), currently operating in the United States, is used for material testing at very high neutron fluxes. Powered with highly enriched uranium (HEU), the ATR has a maximum thermal power rating of 250 MWth. Because of the large test volumes located in high flux areas, the ATR is an ideal candidate for assessing the feasibility of converting HEU driven reactor cores to low-enriched uranium (LEU) cores. The burnable absorber - 10B, was added in the inner and outer plates to reduce the initial excess reactivity, and to improve the peak ratio of the inner/outer heat flux. The present work investigates the LEU Monolithic foil-type fuel with 10B Integral Cladding Burnable Absorber (ICBA) design and evaluates the subsequent neutronics operating effects of this proposed fuel designs. The proposed LEU fuel specification in this work is directly related to both the RERTR LEU Development Program and the Advanced Test Reactor (ATR) LEU Conversion Project at Idaho National Laboratory (INL).

  2. Conceptual design of quadriso particles with europium burnable absorber in HTRS.

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, A.; Nuclear Engineering Division

    2010-05-18

    In High Temperature Reactors, burnable absorbers are utilized to manage the excess reactivity at the early stage of the fuel cycle. In this study QUADRISO particles are proposed to manage the initial xcess reactivity of High Temperature Reactors. The QUADRISO concept synergistically couples the decrease of the burnable poison with the decrease of the fissile materials at the fuel particle level. This echanism is set up by introducing a burnable poison layer around the fuel kernel in ordinary TRISO particles or by mixing the burnable poison with any of the TRISO coated layers. At the beginning of life, the nitial excess reactivity is small because some neutrons are absorbed in the burnable poison and they are prevented from entering the fuel kernel. At the end of life, when the absorber is almost depleted, ore eutrons stream into the fuel kernel of QUADRISO particles causing fission reactions. The mechanism has been applied to a prismatic High Temperature Reactor with europium or erbium burnable absorbers, showing a significant reduction in the initial excess reactivity of the core.

  3. Improved Neutronics Treatment of Burnable Poisons for the Prismatic HTR

    Energy Technology Data Exchange (ETDEWEB)

    Y. Wang; A. A. Bingham; J. Ortensi; C. J. Permann

    2012-10-01

    In prismatic block High Temperature Reactors (HTR), highly absorbing material such a burnable poison (BP) cause local flux depressions and large gradients in the flux across the blocks which can be a challenge to capture accurately with traditional homogenization methods. The purpose of this paper is to quantify the error associated with spatial homogenization, spectral condensation and discretization and to highlight what is needed for improved neutronics treatments of burnable poisons for the prismatic HTR. A new triangular based mesh is designed to separate the BP regions from the fuel assembly. A set of packages including Serpent (Monte Carlo), Xuthos (1storder Sn), Pronghorn (diffusion), INSTANT (Pn) and RattleSnake (2ndorder Sn) is used for this study. The results from the deterministic calculations show that the cross sections generated directly in Serpent are not sufficient to accurately reproduce the reference Monte Carlo solution in all cases. The BP treatment produces good results, but this is mainly due to error cancellation. However, the Super Cell (SC) approach yields cross sections that are consistent with cross sections prepared on an “exact” full core calculation. In addition, very good agreement exists between the various deterministic transport and diffusion codes in both eigenvalue and power distributions. Future research will focus on improving the cross sections and quantifying the error cancellation.

  4. Report on the evaluation of the tritium producing burnable absorber rod lead test assembly. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    This report describes the design and fabrication requirements for a tritium-producing burnable absorber rod lead test assembly and evaluates the safety issues associated with tritium-producing burnable absorber rod irradiation on the operation of a commercial light water reactor. The report provides an evaluation of the tritium-producing burnable absorber rod design and concludes that irradiation can be performed within U.S. Nuclear Regulatory Commission regulations applicable to a commercial pressurized light water reactor.

  5. A reduced-boron OPR1000 core based on the BigT burnable absorber

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hwan Yeal; Yahya, Mohd-Syukri; Kim, Yong Hee [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon (Korea, Republic of)

    2016-04-15

    Reducing critical boron concentration in a commercial pressurized water reactor core offers many advantages in view of safety and economics. This paper presents a preliminary investigation of a reduced-boron pressurized water reactor core to achieve a clearly negative moderator temperature coefficient at hot zero power using the newly-proposed 'Burnable absorber-Integrated Guide Thimble' (BigT) absorbers. The reference core is based on a commercial OPR1000 equilibrium configuration. The reduced-boron ORP1000 configuration was determined by simply replacing commercial gadolinia-based burnable absorbers with the optimized BigT-loaded design. The equilibrium cores in this study were directly searched via repetitive Monte Carlo depletion calculations until convergence. The results demonstrate that, with the same fuel management scheme as in the reference core, application of the BigT absorbers can effectively reduce the critical boron concentration at the beginning of cycle by about 65 ppm. More crucially, the analyses indicate promising potential of the reduced-boron OPR1000 core with the BigT absorbers, as its moderator temperature coefficient at the beginning of cycle is clearly more negative and all other vital neutronic parameters are within practical safety limits. All simulations were completed using the Monte Carlo Serpent code with the ENDF/B-VII.0 library.

  6. Preliminary Nuclear Analysis for the HANARO Fuel Element with Burnable Absorber

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Chul Gyo; Kim, So Young; In, Won Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Burnable absorber is used for reducing reactivity swing and power peaking in high performance research reactors. Development of the HANARO fuel element with burnable absorber was started in the U-Mo fuel development program at HANARO, but detailed full core analysis was not performed because the current HANARO fuel management system is uncertain to analysis the HANARO core with burnable absorber. A sophisticated reactor physics system is required to analysis the core. The McCARD code was selected and the detailed McCARD core models, in which the basic HANARO core model was developed by one of the McCARD developers, are used in this study. The development of nuclear fuel requires a long time and correct developing direction especially by the nuclear analysis. This paper presents a preliminary nuclear analysis to promote the fuel development. Based on the developed fuel, the further nuclear analysis will improve reactor performance and safety. Basic nuclear analysis for the HANARO and the AHR were performed for getting the proper fuel elements with burnable absorber. Addition of 0.3 - 0.4% Cd to the fuel meat is promising for the current HANARO fuel element. Small addition of burnable absorber may not change any fuel characteristics of the HANARO fuel element, but various basic tests and irradiation tests at the HANARO core are required.

  7. Incorporation of Integral Fuel Burnable Absorbers Boron and Gadolinium into Zirconium-Alloy Fuel Clad Material

    Energy Technology Data Exchange (ETDEWEB)

    Sridharan, K.; Renk, T.J.; Lahoda, E.J.; Corradini, M.L

    2004-12-14

    Long-lived fuels require the use of higher enrichments of 235U or other fissile materials. Such high levels of fissile material lead to excessive fuel activity at the beginning of life. To counteract this excessive activity, integral fuel burnable absorbers (IFBA) are added to some rods in the fuel assembly. The two commonly used IFBA elements are gadolinium, which is added as gadolinium-oxide to the UO2 powder, and boron, which is applied as a zirconium-diboride coating on the UO2 pellets using plasma spraying or chemical vapor deposition techniques. The incorporation of IFBA into the fuel has to be performed in a nuclear-regulated facility that is physically separated from the main plant. These operations tend to be very costly because of their small volume and can add from 20 to 30% to the manufacturing cost of the fuel. Other manufacturing issues that impact cost and performance are maintaining the correct levels of dosing, the reduction in fuel melting point due to gadolinium-oxide additions, and parasitic neutron absorption at fuel's end-of-life. The goal of the proposed research is to develop an alternative approach that involves incorporation of boron or gadolinium into the outer surface of the fuel cladding material rather than as an additive to the fuel pellets. This paradigm shift will allow for the introduction of the IFBA in a non-nuclear regulated environment and will obviate the necessity of additional handling and processing of the fuel pellets. This could represent significant cost savings and potentially lead to greater reproducibility and control of the burnable fuel in the early stages of the reactor operation. The surface alloying is being performed using the IBEST (Ion Beam Surface Treatment) process developed at Sandia National Laboratories. IBEST involves the delivery of energetic ion beam pulses onto the surface of a material, near-surface melting, and rapid solidification. The non-equilibrium nature of such processing allows for

  8. IRRADIATION TESTING OF THE RERTR FUEL MINIPLATES WITH BURNABLE ABSORBERS IN THE ADVANCED TEST REACTOR

    Energy Technology Data Exchange (ETDEWEB)

    I. Glagolenko; D. Wachs; N. Woolstenhulme; G. Chang; B. Rabin; C. Clark; T. Wiencek

    2010-10-01

    Based on the results of the reactor physics assessment, conversion of the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL) can be potentially accomplished in two ways, by either using U-10Mo monolithic or U-7Mo dispersion type plates in the ATR fuel element. Both designs, however, would require incorporation of the burnable absorber in several plates of the fuel element to compensate for the excess reactivity and to flatten the radial power profile. Several different types of burnable absorbers were considered initially, but only borated compounds, such as B4C, ZrB2 and Al-B alloys, were selected for testing primarily due to the length of the ATR fuel cycle and fuel manufacturing constraints. To assess and compare irradiation performance of the U-Mo fuels with different burnable absorbers we have designed and manufactured 28 RERTR miniplates (20 fueled and 8 non-fueled) containing fore-mentioned borated compounds. These miniplates will be tested in the ATR as part of the RERTR-13 experiment, which is described in this paper. Detailed plate design, compositions and irradiations conditions are discussed.

  9. Advanced neutron absorber materials

    Science.gov (United States)

    Branagan, Daniel J.; Smolik, Galen R.

    2000-01-01

    A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

  10. A feasibility study for the application of enriched gadolinia burnable absorber rods in nuclear core design

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chung Chan; Zee, Sung Quun; Kim, Kang Seog; Song, Jae Seung

    2000-12-01

    An analysis model using MICBURN-3/CASMO-3 is established for the enriched gadolinia burnable absorber rods. A homogenized cross section editing code, PROLOG, is modified so that it can handle such a fuel assembly that includes two different types of gadolinia rods. Study shows that Gd-155 and Gd-157 are almost same in suppressing the excess reactivity and it is recommended to enrich both odd number isotopes, Gd-155 and Gd-157. It is estimated that the cycle length increases by 2 days if enriched gadolinia rods are used in the commercial nuclear power plant such as YGN-3 of which the cycle length is assumed 2 years. For the advanced integral reactor SMART in which ultra long cycle length and soluble boron-free operation concept is applied, natural gadolinia burnable absorber rods fail to control the excess reactivity. On the other hand, enriched gadolinia rods are successful in controling the excess reactivity. To minimize power peakings, various placements of gadolinia rods are tested. Also initial reactivity holddown and gadolinia burnout time are parametrized with respect to the number of gadolinia rods and gadolinia weight fractions.

  11. Reactivity and neutron flux measurements in IPEN/MB-01 reactor with B{sub 4}C burnable poison; Medidas de reatividade e de fluxo de neutrons no reator IPEN/MB-01 com veneno queimavel de B{sub 4}C

    Energy Technology Data Exchange (ETDEWEB)

    Fer, Nelson Custodio; Moreira, Joao Manoel Losada [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), SP (Brazil)

    2000-07-01

    Burnable poison rods, made of B{sub 4}C- Al{sub 2} O{sub 3} pellets with 5.01 mg/cm{sup 3} {sup 10} B concentration, have been manufactured for a set of experiments in the IPEN/MB-01 zero-power reactor. Several core parameters which are affected by the burnable poisons rods have been measured. The principal results, for the situation in which the burnable poison rods are located near the absorber rods of a control rod, are they cause a 29% rod worth shadowing, a reduction of 39% in the local void coefficient of reactivity, a reduction of 4.8% in the isothermal temperature coefficient of reactivity, and a reduction of 9% in the thermal neutron flux in the region where the burnable poison rods are located. These experimental results will be used for the validation of burnable poison calculation methods in the CTMSP. (author)

  12. Neutron absorbing alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Masayuki

    1998-12-04

    The neutron absorbing alloy of the present invention comprises Ti or an alloy thereof as a mother material, to which from 2 to 40% by weight of Hf and Gd within a range of from 4 to 50% by weight in total are added respectively. Ti is excellent in specific strength, corrosion resistance and workability, and produces no noxious intermetallic compound with Hf and Gd. In addition, since the alloy can incorporate a great quantity of Hf and Gd, a neutron absorbing material having excellent neutron absorbing performance than usual and excellent in specific strength, corrosion resistance and workability can be manufactured conveniently and economically not by a special manufacturing method. (T.M.)

  13. Microstructural Characterization of Burnable Absorber Materials Being Evaluated for Application in LEU U-Mo Fuel Plates

    Energy Technology Data Exchange (ETDEWEB)

    J. F. Jue; B. Miller; B. Yao; E. Perez; Y. H. Sohn

    2011-03-01

    The starting microstructure of a fuel plate will impact how it performs during irradiation. As a result, microstructural characterization has been performed on as-fabricated monolithic fuel plates to determine the changes in fuel plate microstructure that may result from changes in fabrication parameters. Particular focus has been given to the fuel plate U-10Mo/Zr and Zr/AA6061 cladding interfaces, since the integrity of these interfaces will play a big role in determining the overall performance of the fuel plate during irradiation. In addition, burnable absorber materials for potential incorporation into monolithic fuel plates have been characterized to identify their as-fabricated microstructures. This information will be important when trying to understand the PIE data from fuel plates with burnable absorbers that are irradiated in future irradiation experiments. This paper will focus on the microstructures observed using optical metallography, X-ray diffraction, and scanning and transmission electron microscopy for monolithic fuel plates exposed to different fabrication parameters and for as-fabricated burnable absorber materials.

  14. A study on the nuclear characteristics of enriched gadolinia burnable absorber rods; the final report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chung Chan; Zee, Quun; Song, J. S.; Cho, B. O.; Joo, H. G.; Park, S. Y.; Kim, H. Y.; Cho, J. Y.; Kim, K. S

    2001-12-01

    An analysis model using MICBURN-3/CASMO-3 is established for the enriched gadolinia burnable absorber rods. A homogenized cross section editing code, PROLOG, is modified so that it can handle such a fuel assembly that includes two different types of gadolinia rods. Study shows that Gd-155 and Gd-157 are almost same characteristics in suppressing the excess reactivity and it is recommended to enrich both odd number isotopes, Gd-155 and Gd-157. To minimize power peakings, various placements of gadolinia rods are tested. Also initial reactivity holddown and gadolinia burnout time are parametrized with respect to the number of gadolinia rods and gadolinia weight fractions. Cycle length increases by 8 days if enriched gadolinia rods are used in the commercial nuclear power plant such as YGN-3 with 2 year-cycle-length. The nuclear characteristics such as soluble boron concentrations and power distributions are almost same. The maximum power of the gadolinia rods are slightly increased but gadolinia contents are reduced. For SMART with ultra longer cycle length and soluble boron-free operation concept cycle length can be extended by maximum 90 days due to increased fuel loading.

  15. Corrosion resistant neutron absorbing coatings

    Science.gov (United States)

    Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  16. A study on the nuclear characteristics of enriched gadolinia burnable absorber rods; the first year (2000) report

    Energy Technology Data Exchange (ETDEWEB)

    Zee, Sung Quun; Lee, C.C.; Song, J. S.; Cho, B. O.; Joo, H. G.; Park, S. Y.; Kim, H. Y.; Cho, J. Y.; Kim, K. S

    2001-04-01

    An analysis model using MICBURN-3/CASMO-3 is established for the enriched gadolinia burnable absorber rods. A homogenized cross section editing code, PROLOG, is modified so that it can handle such a fuel assembly that includes two different types of gadolinia rods. Study shows that Gd-155 and Gd-157 are almost same in suppressing the excess reactivity and it is recommended to enrich both odd number isotopes, Gd-155 and Gd-157. It is estimated that the cycle length increases by 2 days if enriched gadolinia rods are used in the commercial nuclear power plant such as YGN-3 of which the cycle length is assumed 2 years. For the advanced integral reactor SMART in which ultra long cycle length and soluble boron-free operation concept is applied, natural gadolinia burnable absorber rods fail to control the excess reactivity. On the other hand, enriched gadolinia rods are successful in controling the excess reactivity. To minimize power peakings, various placements of gadolinia rods are tested. Also initial reactivity holddown and gadolinia burnout time are parametrized with respect to the number of gadolinia rods and gadolinia weight fractions.

  17. Use of gadolinium burnable absorbers in VVER Type Reactors. Validation of WIMS-D/4 code; Empleo del gadolinio como absorbente quemable en los reactores nucleares VVER. Validacion del codigo WIMS-D/4

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez Cardona, Caridad M.; Guerra Valdes, Ramiro; Lopez Aldama, Daniel [Centro de Tecnologia Nuclear, La Habana (Cuba)

    1996-07-01

    Burnable absorbers are not used in current operating WWERs, but in order to optimize the fuel cycle and enhance operational safety, one should also introduce gadolinium or a similar burnable absorber in these reactors. For this purpose adequate tools for properly calculating local effects in hexagonal geometries should be developed and validated. The present gives main results in validating the WIMS-D/4 lattice code for Gd burnable absorber bearing WWER lattices. To validate the code experimental and calculational benchmarks proposed in a IAEA Coordinated Research Program were solved. A code system for the optimization of the Gd axial distribution in a WWER reactor was developed and it also presented here. (author)

  18. A study on the oxidation characteristic of UO{sub 2}-Gd{sub 2}O{sub 3} pellet for recycling of burnable absorber pellet scrap

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K. S.; Song, K. W.; Kang, K. W.; Yang, J. H.; Kim, J. H

    2001-04-01

    The development of recycling process of defective (U,Gd)O{sub 2} scrap is one of the important subject in this project. Among the several burnable absorbers, Gd has a very large neutron absorption cross-section. Therefore, gadolinia bearing UO{sub 2} fuel, (U,Gd)O{sub 2}, has been widely used as a burnable absorber in light water reactors. During the pellet fabrication process, fairly amount of defective (U,Gd)O{sub 2} pellets are produced and it is necessary to recycle the scraps. Generally, the defective scraps are powdered through the oxidation in air in the temperature range of 450 to 550 deg C and then mixed with co-milled powder, and further processed to fabricate (U,Gd)O{sub 2} pellets. In addition, the sintered pellet properties are closely depend on the powder property of oxidized M{sub 3}O{sub 8} powder. Therefore, the careful investigate of oxidation kinetics and related powder property of (U,Gd)O{sub 2} is very important. The oxidation behavior of UO{sub 2}-6wt% Gd{sub 2}O{sub 3} and UO{sub 2}-12wt% Gd{sub 2}O{sub 3} has been studied in the temperature range from 350 to 700 deg C using TGA and XRD techniques in air. UO{sub 2} was necessarily oxidized to U{sub 3}O{sub 8} regardless of oxidation temperature and its weight gain was 4wt%. However, (U,Gd)O{sub 2} exhibit a different oxidation behavior ; The final phase and saturated weight gain depends on oxidation temperature. The saturated weight gain increases with oxidation temperature up to 500deg C and thereafter decreases with temperature. In addition, the amount of weight gain obtained at 500 deg C was smaller in UO{sub 2}-12wt% Gd{sub 2}O{sub 3} than in UO{sub 2}-6wt% Gd{sub 2}O{sub 3} and the final phase at the saturated weight gain was M{sub 3}O{sub 8} in UO{sub 2}-6wt% Gd{sub 2}O{sub 3} but the mixture of M{sub 4}O{sub 9} and M{sub 3}O{sub 8} in UO{sub 2}-12wt% Gd{sub 2}O{sub 3}. It is supposed that Gd substitution for U decreases the equilibrium O/M ratio and thereby enhance the stability of M

  19. A new fast neutron collar for safeguards inspection measurements of fresh low enriched uranium fuel assemblies containing burnable poison rods

    Science.gov (United States)

    Evans, Louise G.; Swinhoe, Martyn T.; Menlove, Howard O.; Schwalbach, Peter; Baere, Paul De; Browne, Michael C.

    2013-11-01

    Safeguards inspection measurements must be performed in a timely manner in order to detect the diversion of significant quantities of nuclear material. A shorter measurement time can increase the number of items that a nuclear safeguards inspector can reliably measure during a period of access to a nuclear facility. In turn, this improves the reliability of the acquired statistical sample, which is used to inform decisions regarding compliance. Safeguards inspection measurements should also maintain independence from facility operator declarations. Existing neutron collars employ thermal neutron interrogation for safeguards inspection measurements of fresh fuel assemblies. A new fast neutron collar has been developed for safeguards inspection measurements of fresh low-enriched uranium (LEU) fuel assemblies containing gadolinia (Gd2O3) burnable poison rods. The Euratom Fast Collar (EFC) was designed with high neutron detection efficiency to make a fast (Cd) mode measurement viable whilst meeting the high counting precision and short assay time requirements of the Euratom safeguards inspectorate. A fast mode measurement reduces the instrument sensitivity to burnable poison rod content and therefore reduces the applied poison correction, consequently reducing the dependence on the operator declaration of the poison content within an assembly. The EFC non-destructive assay (NDA) of typical modern European pressurized water reactor (PWR) fresh fuel assembly designs have been simulated using Monte Carlo N-particle extended transport code (MCNPX) simulations. Simulations predict that the EFC can achieve 2% relative statistical uncertainty on the doubles neutron counting rate for a fast mode measurement in an assay time of 600 s (10 min) with the available 241AmLi (α,n) interrogation source strength of 5.7×104 s-1. Furthermore, the calibration range of the new collar has been extended to verify 235U content in variable PWR fuel designs in the presence of up to 32

  20. Usage of burnable poison on research reactors

    Energy Technology Data Exchange (ETDEWEB)

    Villarino, Eduardo Anibal [INVAP S.E., San Carlos de Bariloche (Argentina)

    2002-07-01

    The fuel assemblies with burnable poison are widely used on power reactors, but there are not commonly used on research reactors. This paper shows a neutronic analysis of the advantages and disadvantages of the burnable poison usage on research reactors. This paper analyses both burnable poison design used on research reactors: Boron on the lateral wall and Cadmium wires. Both designs include a parametric study on the design parameters like the amount and geometry of the burnable poison. This paper presents the design flexibility using burnable poisons, it does not find an optimal or final design, which it will strongly depend on the core characteristics and fuel management strategy. (author)

  1. DESCRIPTION OF THE TRITIUM-PRODUCING BURNABLE ABSORBER ROD FOR THE COMMERCIAL LIGHT WATER REACTOR TTQP-1-015 Rev 19

    Energy Technology Data Exchange (ETDEWEB)

    Burns, Kimberly A.; Love, Edward F.; Thornhill, Cheryl K.

    2012-02-01

    Tritium-producing burnable absorber rods (TPBARs) used in the U.S. Department of Energy’s Tritium Readiness Program are designed to produce tritium when placed in a Westinghouse or Framatome 17x17 fuel assembly and irradiated in a pressurized water reactor (PWR). This document provides an unclassified description of the current design baseline for the TPBARs. This design baseline is currently valid only for Watts Bar reactor production cores. A description of the Lead Use TPBARs will not be covered in the text of the document, but the applicable drawings, specifications and test plan will be included in the appropriate appendices.

  2. Porcelain enamel neutron absorbing material

    Science.gov (United States)

    Iverson, Daniel C.

    1990-01-01

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  3. Evaluation of the presence of a burnable absorber in an assembly 3x3 type PWR; Evaluacion de la presencia de un absorbedor quemable en un ensamble 3x3 tipo PWR

    Energy Technology Data Exchange (ETDEWEB)

    Martinez F, M. A.; Del Valle G, E.; Alonso V, G. [IPN, Escuela Superior de Fisica y Matematicas, Av. IPN s/n, Col. Lindavista, Mexico D. F. 07738 (Mexico)]. e-mail: mike_ipn_esfm@hotmail.com

    2008-07-01

    In the present work the effect is evaluated that causes the presence of a burnable absorber in an adjustment of rods of 3x3 of a fuel assembly type PWR using CASMO-4 code, when comparing the infinite multiplication factor and some average cross sections by means of codes MCNP-4A, CASMO-3 and HELIOS. For this evaluation two cases are evaluated: first consists of an adjustment of rods of 3x3 full completely of fuel and the second consists of a central rod full with a burnable absorber type wet annular burnable absorber (WABA) and the remaining full fuel rods. In both cases the enrichment of the fissile isotopes is varied, for two types of fuel, MOX degree armament and UO{sub 2}. (Author)

  4. Neutron absorbed dose in a pacemaker CMOS

    Energy Technology Data Exchange (ETDEWEB)

    Borja H, C. G.; Guzman G, K. A.; Valero L, C.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Paredes G, L., E-mail: fermineutron@yahoo.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2012-06-15

    The neutron spectrum and the absorbed dose in a Complementary Metal Oxide Semiconductor (CMOS), has been estimated using Monte Carlo methods. Eventually a person with a pacemaker becomes an oncology patient that must be treated in a linear accelerator. Pacemaker has integrated circuits as CMOS that are sensitive to intense and pulsed radiation fields. Above 7 MV therapeutic beam is contaminated with photoneutrons that could damage the CMOS. Here, the neutron spectrum and the absorbed dose in a CMOS cell was calculated, also the spectra were calculated in two point-like detectors in the room. Neutron spectrum in the CMOS cell shows a small peak between 0.1 to 1 MeV and a larger peak in the thermal region, joined by epithermal neutrons, same features were observed in the point-like detectors. The absorbed dose in the CMOS was 1.522 x 10{sup -17} Gy per neutron emitted by the source. (Author)

  5. Development of Improved Burnable Poisons for Commercial Nuclear Power Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Renier, J.A.

    2002-04-17

    Burnable poisons are used in all modern nuclear reactors to permit higher loading of fuel without the necessity of an overly large control rod system. This not only permits a longer core life but can also be used to level the power distribution. Commercial nuclear reactors commonly use B{sub 4}C in separate non-fueled rods and more recently, zirconium boride coatings on the fuel pellets or gadolinium oxide mixed with the fuel. Although the advantages are great, there are problems with using these materials. Boron, which is an effective neutron absorber, transmutes to lithium and helium upon absorption of a neutron. Helium is insoluble and is eventually released to the interior of the fuel rod, where it produces an internal pressure. When sufficiently high, this pressure stress could cause separation of the cladding from the fuel, causing overly high centerline temperatures. Gadolinium has several very strongly absorbing isotopes, but not all have large cross sections and result in residual burnable poison reactivity worth at the end of the fuel life. Even if the amount of this residual absorber is small and the penalty in operation small, the cost of this penalty, even if only several days, can be very high. The objective of this investigation was to study the performance of single isotopes in order to reduce the residual negative reactivity left over at the end of the fuel cycle. Since the behavior of burnable poisons can be strongly influenced by their configuration, four forms for the absorbers were studied: homogeneously mixed with the fuel, mixed with only the outer one-third of the fuel pellet, coated on the perimeter of the fuel pellets, and alloyed with the cladding. In addition, the numbers of fuel rods containing burnable poison were chosen as 8, 16, 64, and 104. Other configurations were chosen for a few special cases. An enrichment of 4.5 wt% {sup 235}U was chosen for most cases for study in order to achieve a 4-year fuel cycle. A standard pressurized

  6. Neutron absorbers and methods of forming at least a portion of a neutron absorber

    Science.gov (United States)

    Guillen, Donna P; Porter, Douglas L; Swank, W David; Erickson, Arnold W

    2014-12-02

    Methods of forming at least a portion of a neutron absorber include combining a first material and a second material to form a compound, reducing the compound into a plurality of particles, mixing the plurality of particles with a third material, and pressing the mixture of the plurality of particles and the third material. One or more components of neutron absorbers may be formed by such methods. Neutron absorbers may include a composite material including an intermetallic compound comprising hafnium aluminide and a matrix material comprising pure aluminum.

  7. Neutron absorbed dose in a pacemaker CMOS

    Energy Technology Data Exchange (ETDEWEB)

    Borja H, C. G.; Guzman G, K. A.; Valero L, C. Y.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Paredes G, L., E-mail: candy_borja@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2011-11-15

    The absorbed dose due to neutrons by a Complementary Metal Oxide Semiconductor (CMOS) has been estimated using Monte Carlo methods. Eventually a person with a pacemaker becomes a patient that must be treated by radiotherapy with a linear accelerator; the pacemaker has integrated circuits as CMOS that are sensitive to intense and pulsed radiation fields. When the Linac is working in Bremsstrahlung mode an undesirable neutron field is produced due to photoneutron reactions; these neutrons could damage the CMOS putting the patient at risk during the radiotherapy treatment. In order to estimate the neutron dose in the CMOS a Monte Carlo calculation was carried out where a full radiotherapy vault room was modeled with a W-made spherical shell in whose center was located the source term of photoneutrons produced by a Linac head operating in Bremsstrahlung mode at 18 MV. In the calculations a phantom made of tissue equivalent was modeled while a beam of photoneutrons was applied on the phantom prostatic region using a field of 10 x 10 cm{sup 2}. During simulation neutrons were isotropically transported from the Linac head to the phantom chest, here a 1 {theta} x 1 cm{sup 2} cylinder made of polystyrene was modeled as the CMOS, where the neutron spectrum and the absorbed dose were estimated. Main damages to CMOS are by protons produced during neutron collisions protective cover made of H-rich materials, here the neutron spectrum that reach the CMOS was calculated showing a small peak around 0.1 MeV and a larger peak in the thermal region, both connected through epithermal neutrons. (Author)

  8. Liquid neutron absorber alternatives for the MPTRR

    Energy Technology Data Exchange (ETDEWEB)

    Jatuff, F.E.; Villarino, E.A. [INVAP S.E., S.C. de Bariloche (Argentina)

    1995-12-31

    The Multi-Purpose Type Research Reactor (MPTRR) control and first shutdown systems consist of six control plates of a Ag-In-Cd alloy. The second shutdown system is given by a liquid neutron absorber, a solution of boric acid, filling the inside of the chimney separating the core from the reflectors. The chimney is composed of four sides (four independent systems), each of them formed by two Zircaloy walls of 0.6 cm, and the empty central space inside (1.8 cm) filled with pure nitrogen during normal operation. The licensing criterion for the second shutdown system (the chimney, for brevity) requires a reactivity worth of {approximately}5000 pcm. The purpose of the work is the analysis of alternative liquid absorbers and the maximum reactivity worth reachable by the second shut-down system.

  9. Nodal Diffusion Burnable Poison Treatment for Prismatic Reactor Cores

    Energy Technology Data Exchange (ETDEWEB)

    A. M. Ougouag; R. M. Ferrer

    2010-10-01

    The prismatic block version of the High Temperature Reactor (HTR) considered as a candidate Very High Temperature Reactor (VHTR)design may use burnable poison pins in locations at some corners of the fuel blocks (i.e., assembly equivalent structures). The presence of any highly absorbing materials, such as these burnable poisons, within fuel blocks for hexagonal geometry, graphite-moderated High Temperature Reactors (HTRs) causes a local inter-block flux depression that most nodal diffusion-based method have failed to properly model or otherwise represent. The location of these burnable poisons near vertices results in an asymmetry in the morphology of the assemblies (or blocks). Hence the resulting inadequacy of traditional homogenization methods, as these “spread” the actually local effect of the burnable poisons throughout the assembly. Furthermore, the actual effect of the burnable poison is primarily local with influence in its immediate vicinity, which happens to include a small region within the same assembly as well as similar regions in the adjacent assemblies. Traditional homogenization methods miss this artifact entirely. This paper presents a novel method for treating the local effect of the burnable poison explicitly in the context of a modern nodal method.

  10. Safety evaluation report related to the Department of Energy`s proposal for the irradiation of lead test assemblies containing tritium-producing burnable absorber rods in commercial light-water reactors. Project Number 697

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-05-01

    The NRC staff has reviewed a report, submitted by DOE to determine whether the use of a commercial light-water reactor (CLWR) to irradiate a limited number of tritium-producing burnable absorber rods (TPBARs) in lead test assemblies (LTAs) raises generic issues involving an unreviewed safety question. The staff has prepared this safety evaluation to address the acceptability of these LTAs in accordance with the provision of 10 CFR 50.59 without NRC licensing action. As summarized in Section 10 of this safety evaluation, the staff has identified issues that require NRC review. The staff has also identified a number of areas in which an individual licensee undertaking irradiation of TPBAR LTAs will have to supplement the information in the DOE report before the staff can determine whether the proposed irradiation is acceptable at a particular facility. The staff concludes that a licensee undertaking irradiation of TPBAR LTAs in a CLWR will have to submit an application for amendment to its facility operating license before inserting the LTAs into the reactor.

  11. Hafnium as a neutron absorber in research reactors

    Energy Technology Data Exchange (ETDEWEB)

    Jatuff, F.E.; Villarino, E.A. [INVAP S.E., S.C. de Bariloche (Argentina)

    1995-12-31

    Research reactors usually require the periodic replacement of control rods because of the burnup of the neutron absorber material, even if devices have been mainly withdrawn. The purpose of this paper is the study of the reactivity worth of hafnium as a neutron absorber in the multi-purpose-type research reactor (MPTRR). The MPTRR design develops 20 MW, and it is configured by five rows of six low-enriched uranium (200% enrichment) materials test reactor fuels inside a Zircaloy chimney. The standard control plates are given by two rows of three plates of silver-indium-cadmium alloy (85% silver, 10% indium, and 5% cadmium, in weight percents; 0.26 cm of maximum absorber width), separating the central three rows of fuel elements from the peripheral first and fifth rows. The burnup of control plates decreases the reactivity worth below the licensing criteria in {approximately}6 months.

  12. Measurements of Neutron-absorbing Elements on Mercury's Surface with the MESSENGER Neutron Spectrometer

    Science.gov (United States)

    Lawrence, David J.; Feldman, William C.; Goldsten, John O.; McCoy, Timothy J.; Blewett, David T.; Boynton, William V.; Evans, Larry G.; Nittler, Larry R.; Rhodes, Edgar A.; Solomon, Sean C.

    2010-05-01

    The Neutron Spectrometer (NS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission has made measurements of cosmic-ray-generated thermal neutrons during each of MESSENGER's three Mercury flybys. These thermal neutron data have allowed us to make the first direct measurements of Mercury's surface elemental composition. Specifically, we show that Mercury's surface is enriched in neutron-absorbing elements and has a measured macroscopic neutron absorption cross section of (70-130) × 10^(-4) cm^2/g, which is similar to the neutron absorption of lunar basalts from Mare Fecunditatis. The expected neutron-absorbing elements are Fe and Ti, with possible trace amounts of Gd and Sm. Fe and Ti, in particular, are important for understanding Mercury's formation and how its surface may have changed over time through magmatic processes. With the neutron Doppler filter technique - a neutron energy separation technique based on spacecraft velocity - we demonstrate that Mercury's surface composition cannot be matched by prior models having characteristically low abundances of Fe, Ti, Gd, and Sm. While neutron spectroscopy alone cannot separate the relative contributions of individual neutron-absorbing elements, these results provide strong new constraints on the nature of Mercury's surface materials. For example, if all the measured neutron absorption were due to the presence of a Fe-Ti oxide and that oxide were ilmenite, then Mercury's surface would have an ilmenite content of 14 to 31 wt.%. This result is in agreement with the inference from color imaging and visible-near-infrared spectroscopy that Mercury's overall low reflectance is consistent with a surface composition that is enriched in Fe-Ti oxides. The incorporation of substantial Fe and Ti in oxides would imply that the oxygen fugacity of basalts on Mercury is at the upper range of oxygen fugacity inferred for basalts on the Moon.

  13. Alternative materials to cadmium for neutron absorbers in safeguards applications

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, Corey R [Los Alamos National Laboratory; Geist, William H [Los Alamos National Laboratory; West, James D [Los Alamos National Laboratory

    2009-01-01

    Cadmium is increasingly difficult to use in safeguards applications because of rising cost and increased safety regulations. This work examines the properties of two materials produced by Ceradyne, inc. that present alternatives to cadmium for neutron shielding. The first is an aluminum metal doped with boron and the second is a boron carbide powder, compressed into a ceramic. Both are enriched in the {sup 10}B isotope. Two sheets of boron doped aluminum (1.1 mm and 5.2mm thick) and one sheet of boron carbide (8.5mm thick) were provided by Ceradyne for testing. An experiment was designed to test the neutron absorption capabilities of these three sheets against two different thicknesses of cadmium (0.6mm and 1.6mm thick). The thinner piece of aluminum boron alloy (1.1mm) performed as well as the cadmium pieces at absorbing neutrons. The thicker aluminum-boron plate provided more shielding than the cadmium sheets and the boron carbide performed best by a relatively large margin. Monte Carlo N-Particle eXtended (MCNPX) transport code modeling of the experiment was performed to provide validaLed computational tools for predicting the behavior of systems in which these materials may be incorporated as alternatives to cadmium. MCNPX calculations predict that approximately 0.17mm of the boron carbide is equivalent to 0.6mm of cadmium. There are drawbacks to these materials that need to be noted when considering using them as replacements for cadmium. Notably, they may need to be thicker than cadmium, and are not malleable, requiring machining to fit any curved forms.

  14. Prototype Stilbene Neutron Collar

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, M. K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shumaker, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Snyderman, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Verbeke, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wong, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-26

    A neutron collar using stilbene organic scintillator cells for fast neutron counting is described for the assay of fresh low enriched uranium (LEU) fuel assemblies. The prototype stilbene collar has a form factor similar to standard He-3 based collars and uses an AmLi interrogation neutron source. This report describes the simulation of list mode neutron correlation data on various fuel assemblies including some with neutron absorbers (burnable Gd poisons). Calibration curves (doubles vs 235U linear mass density) are presented for both thermal and fast (with Cd lining) modes of operation. It is shown that the stilbene collar meets or exceeds the current capabilities of He-3 based neutron collars. A self-consistent assay methodology, uniquely suited to the stilbene collar, using triples is described which complements traditional assay based on doubles calibration curves.

  15. Waste Package Neutron Absorber, Thermal Shunt, and Fill Gas Selection Report

    Energy Technology Data Exchange (ETDEWEB)

    V. Pasupathi

    2000-01-28

    Materials for neutron absorber, thermal shunt, and fill gas for use in the waste package were selected using a qualitative approach. For each component, selection criteria were identified; candidate materials were selected; and candidates were evaluated against these criteria. The neutron absorber materials evaluated were essentially boron-containing stainless steels. Two candidates were evaluated for the thermal shunt material. The fill gas candidates were common gases such as helium, argon, nitrogen, carbon dioxide, and dry air. Based on the performance of each candidate against the criteria, the following selections were made: Neutron absorber--Neutronit A978; Thermal shunt--Aluminum 6061 or 6063; and Fill gas--Helium.

  16. Development of a highly efficient burnable poison matrix material for cycle lifetime extension

    Energy Technology Data Exchange (ETDEWEB)

    Tulenko, J.S. [Florida Univ., 202 Nuclear Science Center, Gainesville, FL (United States); Baney, R.H.; Pressley, L. [Florida Univ., Gainesville, FL (United States)

    2001-07-01

    The University of Florida (UF) is carrying out basic research on a new class of thermally stable boron containing materials that from early indications appear to have special properties that will greatly enhance the performance of Burnable Poison Rod Assemblies (BPRA(tm)s) and address one of the major disadvantages of the use of boron shims. The new class of polymer materials, poly-acetylenic carbonyl-siloxane, termed ''Carborane'', were developed by Dr. T. Keller of the Naval Research Laboratory (NRL). Dr. T. Keller is cooperating in this research effort. Other classes of boron containing polymer materials are also under review. Displacement of water by the boron shims incurs an ''end of cycle reactivity penalty'' since at the end of cycle the moderator coefficient is strongly negative. ''Carborane'' has the property of being able to contain a tailored amount of boron while maintaining an extremely high hydrogen content, and at the same time being extremely stable to high temperatures and to neutron irradiation. Tests run by the NRL have shown that ''Carborane'' is stable to about 1000 C. The high hydrogen and carbon content contained in the ''Carborane'' Polymer offsets the large fuel cycle reactivity penalty which occurs with current generation BPRA(tm)s, as a result of the reactivity loss resulting from the BPRA(tm)s displacement of moderator water in the guide tubes of Pressurized Water Reactor (PWR) assemblies. Current generation BPRA utilize B{sub 4}C in an Al{sub 2}O{sub 3} matrix. In an attempt to minimize the reactivity penalty from water displacement, Westinghouse has developed a costly annular BPRA, called the Wet Annular Burnable Absorber (WABA) assembly. This burnable poison rod design reduces the moderator displacement by 22% by the use of a central annular water hole. The ''Carborane'' matrix proposed by the University of Florida

  17. Boron cage compound materials and composites for shielding and absorbing neutrons

    Science.gov (United States)

    Bowen, III, Daniel E; Eastwood, Eric A

    2014-03-04

    Boron cage compound-containing materials for shielding and absorbing neutrons. The materials include BCC-containing composites and compounds. BCC-containing compounds comprise a host polymer and a BCC attached thereto. BCC-containing composites comprise a mixture of a polymer matrix and a BCC filler. The BCC-containing materials can be used to form numerous articles of manufacture for shielding and absorbing neutrons.

  18. Neutronic analysis of absorbing materials for the control rod system in reactor ALLEGRO

    Energy Technology Data Exchange (ETDEWEB)

    Cajko, Frantisek; Secansky, Michal; Chrebet, Tomas; Zajac, Radoslav; Darilek, Petr [VUJE, a.s., Trnava (Slovakia)

    2016-09-15

    Experimental reactor ALLEGRO is a gas cooled fast reactor in the design stage. The current design of its reactivity control system is based on control rods filled with boron carbide as the absorber. Because of disadvantages connected to high boron enrichment a possibility of using other absorbent materials was explored to lower the boron enrichment and increase the worth of the control rods. The results of neutronic Monte-Carlo analyses in a computational supercell are presented in this paper. Three absorbent materials most suitable for a use in reactor ALLEGRO (B{sub 4}C, EuB{sub 6} and ReB{sub 2}) have been analysed also in a full core model. A possible benefit of a neutron trap concept is explored as well but materials with satisfactory neutronic properties proved to be not suitable for expected high temperatures in the reactor.

  19. Backscatter gauge description for inspection of neutron absorber content

    Energy Technology Data Exchange (ETDEWEB)

    Dewberry, R. A.; Gibbs, K. M.; Couture, A. H.

    2013-01-19

    This paper describes design, calibration, and testing of a dual He-3 detector neutron backscatter gauge for use in the Savannah River Site Mixed Oxide Fuel project. The gauge is demonstrated to measure boron content and uniformity in concrete slabs used in the facility construction.

  20. Inelastic Neutron Scattering and Separation Coefficient of Absorbed Hydrogen

    DEFF Research Database (Denmark)

    Silvera, I. F.; Nielsen, Mourits

    1976-01-01

    Inelastic neutron scattering and measurement of the ortho-para separation coefficient have been used to study the low lying rotational states of molecular hydrogen adsorbed on activated alumina. The observations are consistent with a picture in which the orientational motion of the molecules...

  1. Gamma ray attenuation coefficient measurement for neutron-absorbent materials

    Energy Technology Data Exchange (ETDEWEB)

    Jalali, Majid [Isfahan Nuclear Science and Technology Research Institute (NSTRT), Reactor and Accelerators Research and Development School, Atomic Energy Organization (Iran, Islamic Republic of)], E-mail: m_jalali@entc.org.ir; Mohammadi, Ali [Faculty of Science, Department of Physics, University of Kashan, Km. 6, Ravand Road, Kashan (Iran, Islamic Republic of)

    2008-05-15

    The compounds Na{sub 2}B{sub 4}O{sub 7}, H{sub 3}BO{sub 3}, CdCl{sub 2} and NaCl and their solutions attenuate gamma rays in addition to neutron absorption. These compounds are widely used in the shielding of neutron sources, reactor control and neutron converters. Mass attenuation coefficients of gamma related to the four compounds aforementioned, in energies 662, 778.9, 867.38, 964.1, 1085.9, 1173, 1212.9, 1299.1,1332 and 1408 keV, have been determined by the {gamma} rays transmission method in a good geometry setup; also, these coefficients were calculated by MCNP code. A comparison between experiments, simulations and Xcom code has shown that the study has potential application for determining the attenuation coefficient of various compound materials. Experiment and computation show that H{sub 3}BO{sub 3} with the lowest average Z has the highest gamma ray attenuation coefficient among the aforementioned compounds.

  2. Comparison of the neutron ambient dose equivalent and ambient absorbed dose calculations with different GEANT4 physics lists

    Science.gov (United States)

    Ribeiro, Rosane Moreira; Souza-Santos, Denison

    2017-10-01

    A comparison between neutron physics lists given by GEANT4, is made in the calculation of the ambient dose equivalent, and ambient absorbed dose, per fluence conversion coefficients (H* (10) / ϕ and D* (10) / ϕ) for neutrons in the range of 10-9 MeV to 15 MeV. Physics processes are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles. Results obtained for QBBC, QGSP_BERT, QGSP_BIC and Neutron High Precision physics lists are compared with values published in ICRP 74 and previously published articles. Neutron high precision physics lists showed the best results in the studied energy range.

  3. Neutron absorbers and detector types for spent fuel verification using the self-interrogation neutron resonance densitometry

    Energy Technology Data Exchange (ETDEWEB)

    Rossa, Riccardo, E-mail: rrossa@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium); Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Borella, Alessandro, E-mail: aborella@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium); Labeau, Pierre-Etienne, E-mail: pelabeau@ulb.ac.be [Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Pauly, Nicolas, E-mail: nipauly@ulb.ac.be [Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Meer, Klaas van der, E-mail: kvdmeer@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium)

    2015-08-11

    The Self-Interrogation Neutron Resonance Densitometry (SINRD) is a passive non-destructive assay (NDA) technique that is proposed for the direct measurement of {sup 239}Pu in a spent fuel assembly. The insertion of neutron detectors wrapped with different neutron absorbing materials, or neutron filters, in the central guide tube of a PWR fuel assembly is envisaged to measure the neutron flux in the energy region close to the 0.3 eV resonance of {sup 239}Pu. In addition, the measurement of the fast neutron flux is foreseen. This paper is focused on the determination of the Gd and Cd neutron filters thickness to maximize the detection of neutrons within the resonance region. Moreover, several detector types are compared to identify the optimal condition and to assess the expected total neutron counts that can be obtained with the SINRD measurements. Results from Monte Carlo simulations showed that ranges between 0.1–0.3 mm and 0.5–1.0 mm ensure the optimal conditions for the Gd and Cd filters, respectively. Moreover, a {sup 239}Pu fission chamber is better suited to measure neutrons close to the 0.3 eV resonance and it has the highest sensitivity to {sup 239}Pu, in comparison with a {sup 235}U fission chamber, with a {sup 3}He proportional counter, and with a {sup 10}B proportional counter. The use of a thin Gd filter and a thick Cd filter is suggested for the {sup 239}Pu and {sup 235}U fission chambers to increase the total counts achieved in a measurement, while a thick Gd filter and a thin Cd filter are envisaged for the {sup 3}He and {sup 10}B proportional counters to increase the sensitivity to {sup 239}Pu. We concluded that an optimization process that takes into account measurement time, filters thickness, and detector size is needed to develop a SINRD detector that can meet the requirement for an efficient verification of spent fuel assemblies.

  4. Thermal Performance and Operation Limit of Heat Pipe Containing Neutron Absorber

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Mo; Jeong, Yeong Shin; Kim, In Guk; Bang, In Choel [UNIST, Ulsan (Korea, Republic of)

    2015-05-15

    Recently, passive safety systems are under development to ensure the core cooling in accidents involving impossible depressurization such as station blackout (SBO). Hydraulic control rod drive mechanisms, passive auxiliary feedwater system (PAFS), Passive autocatalystic recombiner (PAR), and so on are types of passive safety systems to enhance the safety of nuclear power plants. Heat pipe is used in various engineering fields due to its advantages in terms of easy fabrication, high heat transfer rate, and passive heat transfer. Also, the various concepts associated with safety system and heat transfer using the heat pipe were developed in nuclear engineering field.. Thus, our group suggested the hybrid control rod which combines the functions of existing control rod and heat pipe. If there is significant temperature difference between active core and condenser, the hybrid control rod can shutdown the nuclear fission reaction and remove the decay heat from the core to ultimate heat sink. The unique characteristic of the hybrid control rod is the presence of neutron absorber inside the heat pipe. Many previous researchers studied the effect of parameters on the thermal performance of heat pipe. However, the effect of neutron absorber on the thermal performance of heat pipe has not been investigated. Thus, the annular heat pipe which contains B{sub 4}C pellet in the normal heat pipe was prepared and the thermal performance of the annular heat pipe was studied in this study. Hybrid control rod concept was developed as a passive safety system of nuclear power plant to ensure the safety of the reactor at accident condition. The hybrid control rod must contain the neutron absorber for the function as a control rod. So, the effect of neutron absorber on the thermal performance of heat pipe was experimentally investigated in this study. Temperature distributions at evaporator section of annular heat pipe were lower than normal heat pipe due to the larger volume occupied by

  5. Critical experiments on an enriched uranium solution system containing periodically distributed strong thermal neutron absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Rothe, R.E.

    1996-09-30

    A series of 62 critical and critical approach experiments were performed to evaluate a possible novel means of storing large volumes of fissile solution in a critically safe configuration. This study is intended to increase safety and economy through use of such a system in commercial plants which handle fissionable materials in liquid form. The fissile solution`s concentration may equal or slightly exceed the minimum-critical-volume concentration; and experiments were performed for high-enriched uranium solution. Results should be generally applicable in a wide variety of plant situations. The method is called the `Poisoned Tube Tank` because strong neutron absorbers (neutron poisons) are placed inside periodically spaced stainless steel tubes which separate absorber material from solution, keeping the former free of contamination. Eight absorbers are investigated. Both square and triangular pitched lattice patterns are studied. Ancillary topics which closely model typical plant situations are also reported. They include the effect of removing small bundles of absorbers as might occur during inspections in a production plant. Not taking the tank out of service for these inspections would be an economic advantage. Another ancillary topic studies the effect of the presence of a significant volume of unpoisoned solution close to the Poisoned Tube Tank on the critical height. A summary of the experimental findings is that boron compounds were excellent absorbers, as expected. This was true for granular materials such as Gerstley Borate and Borax; but it was also true for the flexible solid composed of boron carbide and rubber, even though only thin sheets were used. Experiments with small bundles of absorbers intentionally removed reveal that quite reasonable tanks could be constructed that would allow a few tubes at a time to be removed from the tank for inspection without removing the tank from production service.

  6. FABRICATION OF GD CONTAINING DUPLEX STAINLESS STEEL SHEET FOR NEUTRON ABSORBING STRUCTURAL MATERIALS

    Directory of Open Access Journals (Sweden)

    YONG CHOI

    2013-10-01

    Full Text Available A duplex stainless steel sheet with 1 wt.% gadolinium was fabricated for a neutron absorbing material with high strength, excellent corrosion resistance, and low cost as well as high neutron absorption capability. The microstructure of the as-cast specimen has typical duplex phases including 31% ferrite and 69% austenite. Main alloy elements like chromium (Cr, nickel (Ni, and gadolinium (Gd are relatively uniformly distributed in the matrix. Gadolinium rich precipitates were present in the grains and at the grain boundaries. The solution treatment at 1070 °C for 50 minutes followed by the hot-rolling above 950 °C after keeping the sheet at 1200 °C for 1.5 hours are important points of the optimum condition to produce a 6 mm-thick plate without cracking.

  7. Response functions for computing absorbed dose to skeletal tissues from neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Bahadori, Amir A; Johnson, Perry; Bolch, Wesley E [Department of Biomedical Engineering, University of Florida, Gainesville, FL (United States); Jokisch, Derek W [Department of Physics and Astronomy, Francis Marion University, Florence, SC (United States); Eckerman, Keith F, E-mail: wbolch@ufl.edu [Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2011-11-07

    Spongiosa in the adult human skeleton consists of three tissues-active marrow (AM), inactive marrow (IM) and trabecularized mineral bone (TB). AM is considered to be the target tissue for assessment of both long-term leukemia risk and acute marrow toxicity following radiation exposure. The total shallow marrow (TM{sub 50}), defined as all tissues lying within the first 50 {mu}m of the bone surfaces, is considered to be the radiation target tissue of relevance for radiogenic bone cancer induction. For irradiation by sources external to the body, kerma to homogeneous spongiosa has been used as a surrogate for absorbed dose to both of these tissues, as direct dose calculations are not possible using computational phantoms with homogenized spongiosa. Recent micro-CT imaging of a 40 year old male cadaver has allowed for the accurate modeling of the fine microscopic structure of spongiosa in many regions of the adult skeleton (Hough et al 2011 Phys. Med. Biol. 56 2309-46). This microstructure, along with associated masses and tissue compositions, was used to compute specific absorbed fraction (SAF) values for protons originating in axial and appendicular bone sites (Jokisch et al 2011 Phys. Med. Biol. 56 6857-72). These proton SAFs, bone masses, tissue compositions and proton production cross sections, were subsequently used to construct neutron dose-response functions (DRFs) for both AM and TM{sub 50} targets in each bone of the reference adult male. Kerma conditions were assumed for other resultant charged particles. For comparison, AM, TM{sub 50} and spongiosa kerma coefficients were also calculated. At low incident neutron energies, AM kerma coefficients for neutrons correlate well with values of the AM DRF, while total marrow (TM) kerma coefficients correlate well with values of the TM{sub 50} DRF. At high incident neutron energies, all kerma coefficients and DRFs tend to converge as charged-particle equilibrium is established across the bone site. In the range of

  8. Nodal Green’s Function Method Singular Source Term and Burnable Poison Treatment in Hexagonal Geometry

    Energy Technology Data Exchange (ETDEWEB)

    A.A. Bingham; R.M. Ferrer; A.M. ougouag

    2009-09-01

    An accurate and computationally efficient two or three-dimensional neutron diffusion model will be necessary for the development, safety parameters computation, and fuel cycle analysis of a prismatic Very High Temperature Reactor (VHTR) design under Next Generation Nuclear Plant Project (NGNP). For this purpose, an analytical nodal Green’s function solution for the transverse integrated neutron diffusion equation is developed in two and three-dimensional hexagonal geometry. This scheme is incorporated into HEXPEDITE, a code first developed by Fitzpatrick and Ougouag. HEXPEDITE neglects non-physical discontinuity terms that arise in the transverse leakage due to the transverse integration procedure application to hexagonal geometry and cannot account for the effects of burnable poisons across nodal boundaries. The test code being developed for this document accounts for these terms by maintaining an inventory of neutrons by using the nodal balance equation as a constraint of the neutron flux equation. The method developed in this report is intended to restore neutron conservation and increase the accuracy of the code by adding these terms to the transverse integrated flux solution and applying the nodal Green’s function solution to the resulting equation to derive a semi-analytical solution.

  9. Standard specification for boron-Based neutron absorbing material systems for use in nuclear spent fuel storage racks

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This specification defines criteria for boron-based neutron absorbing material systems used in racks in a pool environment for storage of nuclear light water reactor (LWR) spent-fuel assemblies or disassembled components to maintain sub-criticality in the storage rack system. 1.2 Boron-based neutron absorbing material systems normally consist of metallic boron or a chemical compound containing boron (for example, boron carbide, B4C) supported by a matrix of aluminum, steel, or other materials. 1.3 In a boron-based absorber, neutron absorption occurs primarily by the boron-10 isotope that is present in natural boron to the extent of 18.3 ± 0.2 % by weight (depending upon the geological origin of the boron). Boron, enriched in boron-10 could also be used. 1.4 The materials systems described herein shall be functional – that is always be capable to maintain a B10 areal density such that subcriticality Keff <0.95 or Keff <0.98 or Keff < 1.0 depending on the design specification for the service...

  10. Evaluation of Aluminum-Boron Carbide Neutron Absorbing Materials for Interim Storage of Used Nuclear Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lumin [Univ. of Michigan, Ann Arbor, MI (United States). Department of Nuclear Engineering and Radiological Science; Wierschke, Jonathan Brett [Univ. of Michigan, Ann Arbor, MI (United States). Department of Nuclear Engineering and Radiological Science

    2015-04-08

    The objective of this work was to understand the corrosion behavior of Boral® and Bortec® neutron absorbers over long-term deployment in a used nuclear fuel dry cask storage environment. Corrosion effects were accelerated by flowing humidified argon through an autoclave at temperatures up to 570°C. Test results show little corrosion of the aluminum matrix but that boron is leaching out of the samples. Initial tests performed at 400 and 570°C were hampered by reduced flow caused by the rapid build-up of solid deposits in the outlet lines. Analysis of the deposits by XRD shows that the deposits are comprised of boron trioxide and sassolite (H3BO3). The collection of boron- containing compounds in the outlet lines indicated that boron was being released from the samples. Observation of the exposed samples using SEM and optical microscopy show the growth of new phases in the samples. These phases were most prominent in Bortec® samples exposed at 570°C. Samples of Boral® exposed at 570°C showed minimal new phase formation but showed nearly the complete loss of boron carbide particles. Boron carbide loss was also significant in Boral samples at 400°C. However, at 400°C phases similar to those found in Bortec® were observed. The rapid loss of the boron carbide particles in the Boral® is suspected to inhibit the formation of the new secondary phases. However, Material samples in an actual dry cask environment would be exposed to temperatures closer to 300°C and less water than the lowest test. The results from this study conclude that at the temperature and humidity levels present in a dry cask environment, corrosion and boron leaching will have no effect on the performance of Boral® and Bortec® to maintain criticality control.

  11. Visual inspections of the neutron absorber control rods of the IEA-R1 reactor; Inspecoes visuais nas barras absorvedoras de neutrons do reator IEA-R1

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Jose Eduardo R. da; Terremoto, Luis A.A.; Castanheira, Myrthes; Zeituni, Carlos A.; Damy, Margaret de A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Centro de Engenharia Nuclear]. E-mail: jersilva@net.ipen.br

    2002-07-01

    The Fuel Engineering Division at IPEN/CNEN-SP developed facilities for visual inspection of the IEA-R1 fuel elements and neutron absorbing control rod assemblies inside the research reactor pool. This work presents the method of visual inspection performed at IEA-R1 research reactor. These inspections were adopted to evaluate and to follow the state of the Ag-In-Cd control assemblies fabricated at CERCA in 1972 that remain in use at the reactor core. In 1998, 2000 and 20001, visual inspections were performed in these control rod assemblies, which the general conditions were evaluated. (author)

  12. Experimental investigation of space--energy distributions of slow neutrons in water near plane absorber

    Energy Technology Data Exchange (ETDEWEB)

    Hussein, A.; El-Konsol, S.; Novikov, A.; Zakharkin, I.; Hamouda, I.

    1973-12-31

    A mechanical neutron time-of-flight spectrometer was used to measure neutron space-energy distributions near a cadmium plate, of 1 mm thickness, immersed in a water-filled tank. The ET-RR-1 reactor served as a neutron source. Measurements of thermal and resonance neutron distributions, using activation technique, were performed in the tank with and without the cadmium plate. Measurements were made of the neutron spectra emerging normally from the plate ( mu = +1). The spectra were measured at the distances 0, 0.25, 0.5, 1.5, 3.0, and 5.0 cm from the plate surface. An exit tube was used to extract the neutron beam from the region of measurement. The required corrections were introduced to the measured spectra. The measurements are discussed and analyzed in the framework of the neutron temperature approximation. An appreciable softening effect is observed for the measured neutron spectra of mu = +1. The temperature for the spectrum at a distance of 0.25 cm from the plate was 41 deg lower than that of the asymptotic spectrum, and the softening effect relaxed and vanished at a distance of 5 cm. (18 figures) (auth)

  13. The design, microstructure and tensile properties of B{sub 4}C particulate reinforced 6061Al neutron absorber composites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.S. [School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Wang, W.X., E-mail: Wangwenxian@tyut.edu.cn [School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Li, Y.L.; Zhang, P. [School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Nie, H.H. [Shanxi Coal-Mining Administrators College, Taiyuan 030024 (China); Wu, Q.C. [School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

    2015-05-25

    Highlights: • B{sub 4}C/Al composites for neutron shielding were designed by MCNP program. • B{sub 4}C/Al composite were fabricated by vacuum hot pressing followed by hot rolling. • The properties can be enhanced by vacuum hot pressing followed by hot rolling. - Abstract: Based on the Monte Carlo Particle transport program MCNP, a novel boron carbide particulate reinforced 6061Al composite for neutron shielding (B{sub 4}C/6061Al NACs) with high strength and low density was designed. The NACs with four volume fractions (10%, 20%, 30% and 40%) were successfully fabricated by vacuum hot pressing followed by hot rolling (VPHR) in atmospheric environments. The calculation results indicated that the neutron transmission ratio decreased with the increasing of B{sub 4}C content and the thickness of plates. B{sub 4}C particle is uniformly distributed in the matrix, exhibiting the good bonding in interface. The phases of neutron absorbers were mainly B{sub 4}C and Al, and a spot of AlB{sub 2} and Al{sub 3}BC. The grain of the matrix was refined and the dislocation was formed around the particles. With increasing the B{sub 4}C content, the particles gathered, breakage appeared, and the tensile strength of composite first increased and then decreased. The failure mode of B{sub 4}C/6061Al NACs included: the interfacial debonding and the cleavage fracture of particles.

  14. THE CALCULATION OF BURNABLE POISON CORRECTION FACTORS FOR PWR FRESH FUEL ACTIVE COLLAR MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Croft, Stephen [Los Alamos National Laboratory; Favalli, Andrea [Los Alamos National Laboratory; Swinhoe, Martyn T. [Los Alamos National Laboratory

    2012-06-19

    Verification of commercial low enriched uranium light water reactor fuel takes place at the fuel fabrication facility as part of the overall international nuclear safeguards solution to the civilian use of nuclear technology. The fissile mass per unit length is determined nondestructively by active neutron coincidence counting using a neutron collar. A collar comprises four slabs of high density polyethylene that surround the assembly. Three of the slabs contain {sup 3}He filled proportional counters to detect time correlated fission neutrons induced by an AmLi source placed in the fourth slab. Historically, the response of a particular collar design to a particular fuel assembly type has been established by careful cross-calibration to experimental absolute calibrations. Traceability exists to sources and materials held at Los Alamos National Laboratory for over 35 years. This simple yet powerful approach has ensured consistency of application. Since the 1980's there has been a steady improvement in fuel performance. The trend has been to higher burn up. This requires the use of both higher initial enrichment and greater concentrations of burnable poisons. The original analytical relationships to correct for varying fuel composition are consequently being challenged because the experimental basis for them made use of fuels of lower enrichment and lower poison content than is in use today and is envisioned for use in the near term. Thus a reassessment of the correction factors is needed. Experimental reassessment is expensive and time consuming given the great variation between fuel assemblies in circulation. Fortunately current modeling methods enable relative response functions to be calculated with high accuracy. Hence modeling provides a more convenient and cost effective means to derive correction factors which are fit for purpose with confidence. In this work we use the Monte Carlo code MCNPX with neutron coincidence tallies to calculate the influence of

  15. A Neutronic Feasibility Study of an OPR-1000 Core Design with Boron-bearing Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyung Hoon; Park, Sang Yoon; Lee, Chung Chan; Yang, Yong Sik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    In Westinghouse plants, boron is mainly used as a form of the integral fuel burnable absorber (IFBA) with a thin coating of zirconium diboride (ZrB{sub 2}) or wet annular burnable absorber (WABA) with a hollow Al{sub 2}O{sub 3}+B{sub 4}C pellet. In OPR-1000, on the other hand, gadolinia is currently employed as a form of an admixture which consists of Gd{sub 2}O{sub 3} of 6∼8 w/o and UO{sub 2} of natural uranium. Recently, boron-bearing UO{sub 2} fuel (BBF) with the high density of greater than 94%TD has been developed by using a low temperature sintering technique. In this paper, the feasibility of replacing conventional gadolinia-bearing UO{sub 2} fuel (GBF) in OPR-1000 with newly developed boron-bearing fuel is evaluated. Neutronic feasibility study to utilize the BBF in OPR-1000 core has been performed. The results show that the OPR-1000 core design with the BBF is feasible and promising in neutronic aspects. Therefore, the use of the BBF in OPR-1000 can reduce the dependency on the rare material such as gadolinium. However, the burnout of the {sup 10}B isotope results in helium gas, so fuel performance related study with respect to helium generation is needed.

  16. Neutron Diffusion in a Space Lattice of Fissionable and Absorbing Materials

    Science.gov (United States)

    Feynman, R. P.; Welton, T. A.

    1946-08-27

    Methods are developed for estimating the effect on a critical assembly of fabricating it as a lattice rather than in the more simply interpreted homogeneous manner. An idealized case is discussed supposing an infinite medium in which fission, elastic scattering and absorption can occur, neutrons of only one velocity present, and the neutron m.f.p. independent of position and equal to unity with the unit of length used.

  17. Neutronics Analysis of SMART Small Modular Reactor using SRAC 2006 Code

    Science.gov (United States)

    Ramdhani, Rahmi N.; Prastyo, Puguh A.; Waris, Abdul; Widayani; Kurniadi, Rizal

    2017-07-01

    Small modular reactors (SMRs) are part of a new generation of nuclear reactor being developed worldwide. One of the advantages of SMR is the flexibility to adopt the advanced design concepts and technology. SMART (System integrated Modular Advanced ReacTor) is a small sized integral type PWR with a thermal power of 330 MW that has been developed by KAERI (Korea Atomic Energy Research Institute). SMART core consists of 57 fuel assemblies which are based on the well proven 17×17 array that has been used in Korean commercial PWRs. SMART is soluble boron free, and the high initial reactivity is mainly controlled by burnable absorbers. The goal of this study is to perform neutronics evaluation of SMART core with UO2 as main fuel. Neutronics calculation was performed by using PIJ and CITATION modules of SRAC 2006 code with JENDL 3.3 as nuclear data library.

  18. Measurement and Simulation of Thermal Conductivity of Hafnium-Aluminum Thermal Neutron Absorber Material

    Science.gov (United States)

    Guillen, Donna Post; Harris, William H.

    2016-09-01

    A metal matrix composite (MMC) material composed of hafnium aluminide (Al3Hf) intermetallic particles in an aluminum matrix has been identified as a promising material for fast flux irradiation testing applications. This material can filter thermal neutrons while simultaneously providing high rates of conductive cooling for experiment capsules. The purpose of this work is to investigate effects of Hf-Al material composition and neutron irradiation on thermophysical properties, which were measured before and after irradiation. When performing differential scanning calorimetry (DSC) on the irradiated specimens, a large exotherm corresponding to material annealment was observed. Therefore, a test procedure was developed to perform DSC and laser flash analysis (LFA) to obtain the specific heat and thermal diffusivity of pre- and post-annealment specimens. This paper presents the thermal properties for three states of the MMC material: (1) unirradiated, (2) as-irradiated, and (3) irradiated and annealed. Microstructure-property relationships were obtained for the thermal conductivity. These relationships are useful for designing components from this material to operate in irradiation environments. The ability of this material to effectively conduct heat as a function of temperature, volume fraction Al3Hf, radiation damage, and annealing is assessed using the MOOSE suite of computational tools.

  19. Depletion of gadolinium burnable poison in a PWR assembly with high burnup fuel

    Energy Technology Data Exchange (ETDEWEB)

    Refeat, Riham Mahmoud [Nuclear and Radiological Regulatory Authority (NRRA), Cairo (Egypt). Safety Engineering Dept.

    2015-12-15

    A tendency to increase the discharge burnup of nuclear fuel for Advanced Pressurized Water Reactors (PWR) has been a characteristic of its operation for many years. It will be able to burn at very high burnup of about 70 GWd/t with UO{sub 2} fuels. The U-235 enrichment must be higher than 5 %, which leads to the necessity of using an extremely efficient burnable poison like Gadolinium oxide. Using gadolinium isotope is significant due to its particular depletion behavior (''Onion-Skin'' effect). In this paper, the MCNPX2.7 code is used to calculate the important neutronic parameters of the next generation fuels of PWR. K-infinity, local peaking factor and fission rate distributions are calculated for a PWR assembly which burn at very high burnup reaching 70 GWd/t. The calculations are performed using the recently released evaluated Gadolinium cross section data. The results obtained are close to those of a LWR next generation fuel benchmark problem. This demonstrates that the calculation scheme used is able to accurately model a PWR assembly that operates at high burnup values.

  20. Parametric Study of the Effect of Burnable Poison Rods for PWR Burnup Credit

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, J.C.

    2001-09-28

    The Interim Staff Guidance on burnup credit (ISG-8) issued by the United States Nuclear Regulatory Commission's (U.S. NRC) Spent Fuel Project Office recommends restricting the use of burnup credit to assemblies that have not used burnable absorbers. This recommended restriction eliminates a large portion of the currently discharged spent fuel assemblies from cask loading, and thus severely limits the practical usefulness of burnup credit. In the absence of readily available information on burnable poison rod (BPR) design specifications and usage in U.S. pressurized-water-reactors (PWRs), and the subsequent reactivity effect of BPR exposure on discharged spent nuclear fuel (SNF), NRC staff has indicated a need for additional information in these areas. In response, this report presents a parametric study of the effect of BPR exposure on the reactivity of SNF for various BPR designs, fuel enrichments, and exposure conditions, and documents BPR design specifications. Trends in the reactivity effects of BPRs are established with infinite pin-cell and assembly array calculations with the SCALE and HELIOS code packages, respectively. Subsequently, the reactivity effects of BPRs for typical initial enrichment and burnup combinations are quantified based on three-dimensional (3-D) KENO V.a Monte Carlo calculations with a realistic rail-type cask designed for burnup credit. The calculations demonstrate that the positive reactivity effect due to BPR exposure increases nearly linearly with burnup and is dependent on the number, poison loading, and design of the BPRs and the initial fuel enrichment. Expected typical reactivity increases, based on one-cycle BPR exposure, were found to be less than 1% {Delta}k. Based on the presented analysis, guidance is offered on an appropriate approach for calculating bounding SNF isotopic data for assemblies exposed to BPRs. Although the analyses do not address the issue of validation of depletion methods for assembly designs with BPRs

  1. Microstructure and Physical Properties of Tb2TiO5 Neutron Absorber Synthesized by Ball Milling and Sintering

    Science.gov (United States)

    Huang, Jinghua; Ran, Guang; Liu, Tengjiao; Shen, Qiang; Li, Ning

    2016-10-01

    Tb2TiO5 neutron absorber was synthesized by ball milling and sintering. Microstructure character of ball-milled Tb4O7-17.605%TiO2 (mass fraction, %) powders and sintered bulks was analyzed using XRD, SEM and TEM. The microhardness, coefficient of thermal expansion and thermal conductivity of sintered bulks were measured. The experiment results showed that the nanocrystalline solid solution was obtained during ball milling. After 96 h of ball milling, TiO2 was completely solved in Tb4O7 and the crystal size of Tb4O7 was up to 37 nm. The bulk materials prepared by cold isostatic pressing were sintered at 1300 °C. Tb2TiO5 bulks with an orthorhombic structure were obtained. The microhardness of sintered bulks, as well as the thermal conductivity, increased firstly with increasing ball milling time and then decreased. The coefficient of thermal expansion decreased initially and then increased with increasing ball milling time. For the sintered bulk with powder milled for 48 h, the highest values of both microhardness and thermal conductivity were observed, whereas the lowest coefficient of thermal expansion was exhibited. In addition, with increasing testing temperature, the thermal conductivity of sintered bulks initially fell and then rebounded while an opposite trend was found in the coefficient of thermal expansion.

  2. Rare earths as burnable poison for extended cycles control in electricity generation reactors; Etude des terres rares en tant que poison consommable pour le controle des cycles allonges pour les reacteurs electrogenes

    Energy Technology Data Exchange (ETDEWEB)

    Asou, M.

    1995-05-12

    The search of an optimization of the French electronuclear network operations leads to a necessary optimization of the core performances. All the economic studies performed by the utilities had shown that there is a real gain to minimize shut down periods for refueling. So, increasing the cycle length from 12 to 18 months will present a gain of shut down for a three years operation period. The theoretical burnable absorber will be a fuel admixed material bringing the required initial negative reactivity with a burn-up kinetic well suited to the fuel and allowing the lowest residual penalty as possible. The residual penalty us defined in this case by the non complete burn up of the poison, by the low of fissile material and by the accumulate of residual isotopes or nuclides. Because of the well known use of gadolinium as burnable absorber for BWR`s and PWR`s operations, the search for the best compromise to optimize all the above stress is pointed towards the rare earths. In the nuclides family, considering criteria such as cross sections, natural abundance and availability only five nuclides can play the role as burnable absorbers, namely: gadolinium, samarium, dysprosium, europium and erbium. The study presented here will show that only gadolinium and erbium will be considered to control the reactivity of the PWR`s. (author). 58 refs., 65 figs., 47 tabs.

  3. Degradation analysis of neutrons absorber bars Ag-In-Cd. Part 1: alloy depletion, neutrons absorption effectiveness and mechanical properties; Analise da degradacao de barras absorvedoras de neutrons de Ag-In.Cd. Parte 1: deplecao da liga, efetividade de absorcao de neutrons e propriedades mecanicas

    Energy Technology Data Exchange (ETDEWEB)

    Castanheira, Myrthes; Terremoto, Luis Antonio A.; Silva, Jose Eduardo Rosa da; Zeituni, Carlos Alberto [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Centro de Engenharia Nuclear

    2002-07-01

    The original alloy of IEA-R1 reactor absorber bars (supposing similar to alloy 2533 with composition 81,5% Ag - 136% In -4,9% Cd) was designed to work for a life time equivalent to a neutron exposition of {approx}10{sup 21} n/cm{sup 2} (thermal) so that the alloy can preserve the characteristic one phase. Analyzing the behavior of absorber bars Ag-In-Cd under irradiation, this work reports a semi quantitative assessment of the IEA-R1 absorber bars degradation current condition by viewpoint of alloy depletion, neutrons absorption effectiveness and mechanical properties, as a complement of visual inspections results carried out at 1998, 2000 and 2001 whose had pointed to visible degree of degradation accumulated along 29 years of operation in the reactor. (author)

  4. A Preliminary Study on the Conceptual Design of Thorium/Uranium Mixed Nuclear Fuel for the Alternative of Burnable Poison in Commercial Pressurized Water Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Hwan; Kim, Song Hyun; Kim, Jong Kyung [Hanyang Univ., Seoul (Korea, Republic of)

    2013-10-15

    Thorium has higher neutron absorption cross section than that of U-238. Thus, the thorium mixed uranium oxide nuclear fuel can reduce the initial excessive reactivity and the long-live radio-wastes with increasing the fuel utilization efficiency. In this study, a preliminary study on the application of the thorium/uranium mixed fuel is performed for the alternative of the PLUS7 fuel assembly which includes burnable poison. A conceptual design without geometrical change is proposed and the reactor characteristics are analyzed. In this study, a fuel assembly using the uranium/thorium mixed fuel was designed to substitute the assembly which includes burnable poison. The reactor characteristics, which are k{sub inf}, power distribution and plutonium production rate, were evaluated and the results are compared with the E1 assembly which is used in the OPR1000 reactor. The results show that the proposed design can efficiently reduce the excessive reactivity, peak power, and plutonium production with increasing the fuel utilization period.

  5. Effects of limestone petrography and calcite microstructure on OPC clinker raw meals burnability

    Science.gov (United States)

    Galimberti, Matteo; Marinoni, Nicoletta; Della Porta, Giovanna; Marchi, Maurizio; Dapiaggi, Monica

    2016-12-01

    Limestone represents the main raw material for ordinary Portland cement clinker production. In this study eight natural limestones from different geological environments were chosen to prepare raw meals for clinker manufacturing, aiming to define a parameter controlling the burnability. First, limestones were characterized by X-Ray Fluorescence, X-Ray Powder Diffraction and Optical Microscopy to assess their suitability for clinker production and their petrographic features. The average domains size and the microstrain of calcite were also determined by X-Ray Powder Diffraction line profile analysis. Then, each limestone was admixed with clay minerals to achieve the adequate chemical composition for clinker production. Raw meals were thermally threated at seven different temperatures, from 1000 to 1450 °C, to evaluate their behaviour on heating by ex situ X-Ray Powder Diffraction and to observe the final clinker morphology by Scanning Electron Microscopy. Results indicate the calcite microstrain is a reliable parameter to predict the burnability of the raw meals, in terms of calcium silicates growth and lime consumption. In particular, mixtures prepared starting from high-strained calcite exhibit a better burnability. Later, when the melt appears this correlation vanishes; however differences in the early burnability still reflect on the final clinker composition and texture.

  6. The INCA Project II. Measurements of the neutron yield from a lead absorber for pion and proton projectiles

    Science.gov (United States)

    INCA Collaboration

    1999-08-01

    As a part of the program of development of a new instrument called Ionization- Neutron Calorimeter (INCA) aimed at studying primary cosmic radiation, exp erimental data on average values and fluctuations of the neutron yield from a 60-cm-thick lead target are obtained. The target was exposed to pion and proton accelerator b eams with energies of 4 and 70 GeV, resp ectively, and to an electron beam with an energy of 200 to 550 MeV. The exp erimental data obtained well agree with the results of a simulation by the SHIELD code used for development of INCA elements. It is shown that the same particle energy, the average neutron yield for electron pro jectiles is by the factor of approximately 50 lower than for hadrons.

  7. Understanding and predicting the behaviour of silver base neutron absorbers under irradiations; Comprehension et prediction du comportement sous irradiation neutronique d`alliages absorbants a base d`argent

    Energy Technology Data Exchange (ETDEWEB)

    Desgranges, C

    1998-12-31

    The effect of neutron irradiation induced transmutations on the swelling of AgInCd (AIC) alloys used as neutron absorber in the control rods of Pressurized Water Reactors has been studied both experimentally and theoretically. Effective atomic volumes have been determined in synthetic AgCdInSn alloys with various compositions and containing fcc and hc phases, representative of irradiated AIC (Sn is a transmutation product). Swelling is shown to result first from the transmutation of Ag into Cd and of In into Sn, both with larger effective volume than the mother atom, and second from grain boundaries precipitation of s still less dense hc phase when solid solubility of transmuted products is exceeded. For both fcc and hc phases, we have determined profiles at the temperatures in the vicinity of the operating temperature. Unusual characteristics of second phase growth at grain boundaries induced by transmutations are identified on a simple binary alloy model: kinetics is controlled by irradiation temperature which scales diffusivities and flux which scales transmutation rates, as well as by the grain size in the underlying matrix. To address the AgInCdSn alloys, a novel technique is proposed to model diffusion in multicomponent alloys. It is based on a linearization of a simple atomistic model. With a single set of parameters, for each phase, our model well reproduces our interdiffusion measurements in quaternary alloys as well as existing interdiffusion experiments in binary alloys. Finally this diffusion model implemented with a moving interface algorithm is used to model the growth of the second phase induced by transmutation in the AIC under irradiation. (authors) 74 refs.

  8. Application of imaging plate neutron detector to neutron radiography

    CERN Document Server

    Fujine, S; Kamata, M; Etoh, M

    1999-01-01

    As an imaging plate neutron detector (IP-ND) has been available for thermal neutron radiography (TNR) which has high resolution, high sensitivity and wide range, some basic characteristics of the IP-ND system were measured at the E-2 facility of the KUR. After basic performances of the IP were studied, images with high quality were obtained at a neutron fluence of 2 to 7x10 sup 8 n cm sup - sup 2. It was found that the IP-ND system with Gd sub 2 O sub 3 as a neutron converter material has a higher sensitivity to gamma-ray than that of a conventional film method. As a successful example, clear radiographs of the flat view for the fuel side plates with boron burnable poison were obtained. An application of the IP-ND system to neutron radiography (NR) is presented in this paper.

  9. PARTICLE SIZE-DEPENDENT PULVERIZATION OF B4C AND GENERATION OF B4C/STS NANOPARTICLES USED FOR NEUTRON ABSORBING COMPOSITES

    Directory of Open Access Journals (Sweden)

    JAEWOO KIM

    2014-10-01

    Full Text Available Pulverization of two different sized micro-B4C particles (∼10 μm and ∼150 μm was investigated using a STS based high energy ball milling system. Shapes, generation of the impurities, and reduction of the particle size dependent on milling time and initial particle size were investigated using various analytic tools including SEM-EDX, XRD, and ICP-MS. Most of impurity was produced during the early stage of milling, and impurity content became independent on the milling time after the saturation. The degree of particle size reduction was also dependent on the initial B4C size. It was found that the STS nanoparticles produced from milling is strongly bounded with the B4C particles forming the B4C/STS composite particles that can be used as a neutron absorbing nanocomposite. Based on the morphological evolution of the milled particles, a schematic pulverization model for the B4C particles was constructed.

  10. Reactor physics analysis for the design of nuclear fuel lattices with burnable poisons

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa-Paredes, G. [Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico, D.F. (Mexico); Guzman, Juan R., E-mail: maestro_juan_rafael@hotmail.com [Departamento de Fisica y Matematicas, Instituto Politecnico Nacional, Adolfo Lopez Mateos, San Pedro Zacatenco, 07738 Mexico, D.F. (Mexico)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer A fuel rod optimization for the coupled bundle-core design in a BWR is developed. Black-Right-Pointing-Pointer An algorithm to minimize the rod power peaking factor is used. Black-Right-Pointing-Pointer The fissile content is divided in two factors. Black-Right-Pointing-Pointer A reactor physics analysis of these factors is performed. Black-Right-Pointing-Pointer The algorithm is applied to a typical BWR fuel lattice. - Abstract: The main goals in nuclear fuel lattice design are: (1) minimizing the rod power peaking factor (PPF) in order that the power level distribution is the most uniform; (2) obtaining a prescribed target value for the multiplication factor (k) at the end of the irradiation in order that the fuel lattice reaches the desired reactivity; and (3) obtaining a prescribed target value for the k at the beginning of the irradiation in order that the reactivity excess is neither a high value (to ease the maneuvering of the control systems) nor a low value (to avoid the penalization of the high cost of the burnable poison content). In this work a simple algorithm to design the burnable poison bearing nuclear fuel lattice is presented. This algorithm is based on a reactor physics analysis. The algorithm is focused on finding the radial distribution of the fuel rods having different fissile and burnable poison contents in order to obtain: (1) an adequate minimum PPF; (2) a prescribed target value of the k at the end of the irradiation; and (3) a prescribed target value of the k at the beginning of the irradiation. This algorithm is based on the factorization of the fissile and burnable poison contents of each fuel rod and on the application of the first-order perturbation theory. The performance of the algorithm is demonstrated with the design of a fuel lattice composed of uranium dioxide (UO{sub 2}) and gadolinium dioxide (Gd{sub 2}O{sub 3}) for boiling water reactors (BWR). This algorithm has been accomplished

  11. Neutron-absorber release device

    Science.gov (United States)

    VAN Erp, Jan B.; Kimont, Edward L.

    1976-01-01

    A resettable device is provided for supporting an object, sensing when an environment reaches a critical temperature and releasing the object when the critical temperature is reached. It includes a flexible container having a material inside with a melting point at the critical temperature. The object's weight is supported by the solid material which gives rigidity to the container until the critical temperature is reached at which point the material in the container melts. The flexible container with the now fluid material inside has insufficient strength to support the object which is thereby released. Biasing means forces the container back to its original shape so that when the temperature falls below the melting temperature the material again solidifies, and the object may again be supported by the device.

  12. Neutronic Reactor Shield

    Science.gov (United States)

    Fermi, Enrico; Zinn, Walter H.

    The argument of the present Patent is a radiation shield suitable for protection of personnel from both gamma rays and neutrons. Such a shield from dangerous radiations is achieved to the best by the combined action of a neutron slowing material (a moderator) and a neutron absorbing material. Hydrogen is particularly effective for this shield since it is a good absorber of slow neutrons and a good moderator of fast neutrons. The neutrons slowed down by hydrogen may, then, be absorbed by other materials such as boron, cadmium, gadolinium, samarium or steel. Steel is particularly convenient for the purpose, given its effectiveness in absorbing also the gamma rays from the reactor (both primary gamma rays and secondary ones produced by the moderation of neutrons). In particular, in the present Patent a shield is described, made of alternate layers of steel and Masonite (an hydrolized ligno-cellulose material). The object of the present Patent is not discussed in any other published paper.

  13. Nuclear reactor neutron shielding

    Energy Technology Data Exchange (ETDEWEB)

    Speaker, Daniel P; Neeley, Gary W; Inman, James B

    2017-09-12

    A nuclear reactor includes a reactor pressure vessel and a nuclear reactor core comprising fissile material disposed in a lower portion of the reactor pressure vessel. The lower portion of the reactor pressure vessel is disposed in a reactor cavity. An annular neutron stop is located at an elevation above the uppermost elevation of the nuclear reactor core. The annular neutron stop comprises neutron absorbing material filling an annular gap between the reactor pressure vessel and the wall of the reactor cavity. The annular neutron stop may comprise an outer neutron stop ring attached to the wall of the reactor cavity, and an inner neutron stop ring attached to the reactor pressure vessel. An excore instrument guide tube penetrates through the annular neutron stop, and a neutron plug comprising neutron absorbing material is disposed in the tube at the penetration through the neutron stop.

  14. Evaluation of absorbed effective dose and treatment conditions for a brain tumor outside of the head phantom center in treatment by Boron Neutron Capture Therapy Using Monte Carlo Simulation

    Directory of Open Access Journals (Sweden)

    Samira Mirzaiee

    2016-04-01

    (including 252Cf source, moderator, refelector and neutron and photon filters was simulated. A spherical-shaped tumor was considered outside of the phantom center. The head phantom consists of three parts of the skin, skull and brain. The simulation was done by the MCNPX 2.6.0 computational code. In this simulation, the tumor with a radius of 1.5 cm at a depth of 2 cm inside the brain was considered. Results: Tumor treatment was investigated with different boron concentrations in the head phantom. The maximum dose is approximately 0.055 Sv/hr, and is related to the conditions that Boron is not absorbed in healthy tissue. The absorbed dose amount of the epithermal neutrons, under the conditions that Boron is not absorbed in healthy tissue, at the entrance of the skull and in brain tissue extremily drops, and gradually decreases. Conclusion: The calculations showed when a patient receives radiation about 5 minutes, the received dose equals approximately 4.6 mSv.Under these treatment conditions, the whole body equivalent dose  does not exceed 5 mSv per year.

  15. Spectra and absorbed dose by photo-neutrons in a solid water mannequin exposed to a Linac of 15 MV; Espectros y dosis absorbida por fotoneutrones en un maniqui de agua solida expuesta a una Linac de 15 MV

    Energy Technology Data Exchange (ETDEWEB)

    Benites R, J. [Centro Estatal de Cancerologia de Nayarit, Servicio de Seguridad Radiologica, Calz. de la Cruz 118 Sur, 63000 Tepic, Nayarit (Mexico); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Apdo. Postal 336, 98000 Zacatecas (Mexico); Velazquez F, J., E-mail: jlbenitesr@prodigy.net.mx [Universidad Autonoma de Nayarit, Posgrado en Ciencias Biologico Agropecuarias, Carretera Tepic-Compostela Km 9, 63780 Jalisco-Nayarit (Mexico)

    2012-10-15

    Using Monte Carlo methods was modeled a solid water mannequin; according to the ICRU 44 (1989), Tissue substitutes in radiation dosimetry and measurements, of the International Commission on Radiation Units and Measurements; Report 44. This material Wt 1 is made of H (8.1%), C (67.2%), N (2.4%), O (19.9%), Cl (0.1%), Ca (2.3%) and its density is of 1.02 gr/cm{sup 3}. The mannequin was put instead of the patient, inside the treatment room and the spectra and absorbed dose were determined by photo-neutrons exposed to a Linac of 15 MV. (Author)

  16. New long-cycle small modular PWR cores using particle type burnable poisons for low boron operation

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Hoseong; Hwang, Dae Hee [Department of Nuclear Engineering, Kyung Hee University, Deogyeong-daero, GiHeung-gu, Yongin, Gyeonggi-do 446-701 (Korea, Republic of); Hong, Ser Gi, E-mail: sergihong@khu.ac.kr [Department of Nuclear Engineering, Kyung Hee University, Deogyeong-daero, GiHeung-gu, Yongin, Gyeonggi-do 446-701 (Korea, Republic of); Shin, Ho Choel [Core and Fuel Analysis Group, Korea Hydro & Nuclear Power Central Research Institute (KHNP-CRI), Daejon 305-343 (Korea, Republic of)

    2017-04-01

    Highlights: • New advanced burnable poison rods (BPR) are suggested for low boron operation in PWR. • The new SMR cores have long cycle length of ∼4.5 EFPYs with low boron concentration. • The SMR core satisfies all the design targets and constraints. - Abstract: In this paper, new small long-cycle PWR (Pressurized Water Reactor) cores for low boron concentration operation are designed by employing advanced burnable poison rods (BPRs) in which the BISO (Bi-Isotropic) particles of burnable poison are distributed in a SiC matrix. The BPRs are designed by adjusting the kernel diameter, the kernel material and the packing fraction to effectively reduce the excess reactivity in order to reduce the boron concentration in the coolant and achieve a flat change in excess reactivity over a long operational cycle. In addition, axial zoning of the BPRs was suggested to improve the core performances, and it was shown that the suggested axial zoning of BPRs considerably extends the cycle length compared to a core with no BPR axial zoning. The results of the core physics analyses showed that the cores using BPRs with a B{sub 4}C kernel have long cycle lengths of ∼4.5 EFPYs (Effective Full Power Years), small maximum CBCs (Critical Boron Concentration) lower than 370 ppm, low power peaking factors, and large shutdown margins of control element assemblies.

  17. Experimental validation of effectiveness of rod-type burnable poisons on reactivity control in HTTR

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Minoru, E-mail: goto.minoru@jaea.go.j [Japan Atomic Energy Agency, 4002 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki-ken 311-1393 (Japan); Shiozawa, Shusaku; Fujimoto, Nozomu; Nakagawa, Shigeaki [Japan Atomic Energy Agency, 4002 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki-ken 311-1393 (Japan); Nakao, Yasuyuki [Department of Applied Quantum Physics and Nuclear Engineering, Kyusyu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan)

    2010-10-15

    In block-type high temperature gas-cooled reactors (HTGRs), insertion depth of control rods (CRs) into a core should be retained shallow to keep fuel temperature below 1495 {sup o}C through a burnup period, and hence excess reactivity should be reduced through a different method. Loading burnable poisons (BPs) into the core is considered as a method to resolve this problem as in case of light water reactors (LWRs). Effectiveness of BPs on reactivity control in LWRs has been validated by experimental data, however, this has not been done yet for HTGRs, because there was not enough burnup characteristics data for HTGRs required for the validation. The High Temperature Engineering Test Reactor (HTTR) is a block-type HTGRs and it adopts rod-type BPs to control reactivity. The HTTR has been operated up to middle burnup, and thereby the experimental data was expected to show effect of the BPs on the reactivity control. Hence, in order to validate effectiveness of rod-type BPs on reactivity control in the HTTR, we investigated on the HTTR results whether the BPs have functioned as designed. As a result, the CRs insertion depth has been retained shallow within allowable range, and then effectiveness of rod-type BPs on reactivity control in the HTTR was validated.

  18. Study on the Blistering of B4C/Al Neutron Absorber Plate in the Course of Corrosion%B4C/Al中子吸收板腐蚀过程中的起泡研究

    Institute of Scientific and Technical Information of China (English)

    李刚; 王美玲; 王贯春; 简敏

    2012-01-01

    The corrosion model of cladding blistering on B4C/A1 neutron absorber plate was established by Henry's law, and by means of the model to investigate the relationship between pore radius and temperature factors for blistering. Influence of pore size for the neutron absorber plate blistering was analyzed by using the pore capillary effects. The results show that the hydrogen pressure produced in small radius pores is higher due to Al corrosion, which contributed to B4C/A1 neutron absorber plate cladding blistering. Influence of temperature on the corrosion generated hydrogen pressure is very small, but the main factors affecting the hydrogen pressure is the pore radius sizes. Blistering power of the cladding is hydrogen continuous generation and accumulating in the pore capillary. The water diffuses easily through the pore capillary in B4C/A1 cores, which will cause the cladding blistering because of Al corrosion.%根据亨利定律,建立了B4C/Al中子吸收板包壳腐蚀起泡的模型,计算了孔隙半径、温度对起泡的影响,并利用孔隙毛细管效应分析了孔隙对中子吸收板起泡的影响.结果表明:孔隙半径越小,腐蚀产生的氢气压力越大,B4C/Al中子吸收板包壳更易起泡;温度对腐蚀产生的氢气压力影响非常小,而孔隙半径是影响氢气压力的主要因素;氢气持续产生并在孔隙毛细管中积聚,是包壳产生起泡的动力;水分容易通过孔隙毛细管在B4C/Al芯体中扩散,可导致Al腐蚀,引起包壳起泡.

  19. Multi level optimization of burnable poison utilization for advanced PWR fuel management

    Science.gov (United States)

    Yilmaz, Serkan

    The objective of this study was to develop an unique methodology and a practical tool for designing burnable poison (BP) pattern for a given PWR core. Two techniques were studied in developing this tool. First, the deterministic technique called Modified Power Shape Forced Diffusion (MPSFD) method followed by a fine tuning algorithm, based on some heuristic rules, was developed to achieve this goal. Second, an efficient and a practical genetic algorithm (GA) tool was developed and applied successfully to Burnable Poisons (BPs) placement optimization problem for a reference Three Mile Island-1 (TMI-1) core. This thesis presents the step by step progress in developing such a tool. The developed deterministic method appeared to perform as expected. The GA technique produced excellent BP designs. It was discovered that the Beginning of Cycle (BOC) Kinf of a BP fuel assembly (FA) design is a good filter to eliminate invalid BP designs created during the optimization process. By eliminating all BP designs having BOC Kinf above a set limit, the computational time was greatly reduced since the evaluation process with reactor physics calculations for an invalid solution is canceled. Moreover, the GA was applied to develop the BP loading pattern to minimize the total Gadolinium (Gd) amount in the core together with the residual binding at End-of-Cycle (EOC) and to keep the maximum peak pin power during core depletion and Soluble boron concentration at BOC both less than their limit values. The number of UO2/Gd2O3 pins and Gd 2O3 concentrations for each fresh fuel location in the core are the decision variables and the total amount of the Gd in the core and maximum peak pin power during core depletion are in the fitness functions. The use of different fitness function definition and forcing the solution movement towards to desired region in the solution space accelerated the GA runs. Special emphasize is given to minimizing the residual binding to increase core lifetime as

  20. 含碳化硼的吸收和屏蔽中子辐射涂料的研究%Boron Carbide Containing Paint Absorbing and Shielding Neutron Radiation

    Institute of Scientific and Technical Information of China (English)

    黄益平; 冯惠生; 梁璐; 徐姣; 张卫江

    2011-01-01

    对碳化硼(B4C)/环氧树脂涂料合成工艺进行研究,制得一种以793树脂作为固化剂的能屏蔽和吸收中子辐射的涂料.对B4C/环氧树脂涂料的成膜条件及不同含量B4C涂料的硬度、抗冲击性、附着力和柔韧性等物理机械性能进行测试研充结果表明,含有30% B4C的环氧树脂涂料的总体机械性能最佳.在此基础上,考察了不同涂膜厚度下B4C/环氧树脂涂料的防中子辐射的性能,薄膜厚度超过300 μm时,可以有效屏蔽中子射线.%The synthesis technology of boron carbide (B4C)/epoxy resin paint was investigated, and the paint with the ability of absorbing and shielding the neutron radiation, solidified by 793 resin, was obtained. The film-forming conditions of B4C / epoxy resin paint were treated; meanwhile, the relationship between the different contents of B4C in the paint and hardness, impact resistance, adhesion, flexibility and other physical testing of mechanical properties was studied. The conclusion was obtained that the overall machinery of B4C/epoxy paint has better performance with 30% B4C. Furthermore, The anti-neutron radiation performance of B4C/epoxy paint with different film thicknesses was also examined. Results show that effective neutron radiation shielding can be achieved when the film thickness exceeds 300 nm.

  1. Implementation of strength pareto evolutionary algorithm II in the multiobjective burnable poison placement optimization of KWU pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Gharari, Rahman [Nuclear Science and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of); Poursalehi, Navid; Abbasi, Mohmmadreza; Aghale, Mahdi [Nuclear Engineering Dept, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

    2016-10-15

    In this research, for the first time, a new optimization method, i.e., strength Pareto evolutionary algorithm II (SPEA-II), is developed for the burnable poison placement (BPP) optimization of a nuclear reactor core. In the BPP problem, an optimized placement map of fuel assemblies with burnable poison is searched for a given core loading pattern according to defined objectives. In this work, SPEA-II coupled with a nodal expansion code is used for solving the BPP problem of Kraftwerk Union AG (KWU) pressurized water reactor. Our optimization goal for the BPP is to achieve a greater multiplication factor (K-e-f-f) for gaining possible longer operation cycles along with more flattening of fuel assembly relative power distribution, considering a safety constraint on the radial power peaking factor. For appraising the proposed methodology, the basic approach, i.e., SPEA, is also developed in order to compare obtained results. In general, results reveal the acceptance performance and high strength of SPEA, particularly its new version, i.e., SPEA-II, in achieving a semioptimized loading pattern for the BPP optimization of KWU pressurized water reactor.

  2. Sound Absorbers

    Science.gov (United States)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  3. Absorbed dose by a CMOS in radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Borja H, C. G.; Valero L, C. Y.; Guzman G, K. A.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Paredes G, L. C., E-mail: candy_borja@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2011-10-15

    Absorbed dose by a complementary metal oxide semiconductor (CMOS) circuit as part of a pacemaker, has been estimated using Monte Carlo calculations. For a cancer patient who is a pacemaker carrier, scattered radiation could damage pacemaker CMOS circuits affecting patient's health. Absorbed dose in CMOS circuit due to scattered photons is too small and therefore is not the cause of failures in pacemakers, but neutron calculations shown an absorbed dose that could cause damage in CMOS due to neutron-hydrogen interactions. (Author)

  4. Absorbed dose by a CMOS in radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Borja H, C. G.; Valero L, C. Y.; Guzman G, K. A.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Paredes G, L. C., E-mail: candy_borja@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2011-10-15

    Absorbed dose by a complementary metal oxide semiconductor (CMOS) circuit as part of a pacemaker, has been estimated using Monte Carlo calculations. For a cancer patient who is a pacemaker carrier, scattered radiation could damage pacemaker CMOS circuits affecting patient's health. Absorbed dose in CMOS circuit due to scattered photons is too small and therefore is not the cause of failures in pacemakers, but neutron calculations shown an absorbed dose that could cause damage in CMOS due to neutron-hydrogen interactions. (Author)

  5. "m=1" coatings for neutron guides

    DEFF Research Database (Denmark)

    Cooper-Jensen, C.P.; Vorobiev, A.; Klinkby, Esben Bryndt

    2014-01-01

    A substantial part of the price for a neutron guide is the shielding needed because of the gamma ray produced when neutrons are absorbed. This absorption occurs in the coating and the substrate of the neutron guides. Traditional m=1 coatings have been made of Ni and if reflectivity over...... the critical angle of Ni is needed one has used Ni58 or Ni/Ti multilayer coatings. Ni has one of the highest neutron scattering density but it also has a fairly high absorption cross section for cold and thermal neutrons and when a neutron is absorbed it emits a lot of gamma rays, some with energies above 9 Me......V. Materials like diamond and Be have higher neutron scattering density than Ni, have smaller absorption cross section and when a neutron is absorbed they emit much less gamma ray and at lower energies. We present results, both theoretically and experimentally, comparing Ni with Be and preliminary results...

  6. A novel Fe–Cr–Nb matrix composite containing the TiB{sub 2} neutron absorber synthesized by mechanical alloying and final hot isostatic pressing (HIP) in the Ti-tubing

    Energy Technology Data Exchange (ETDEWEB)

    Litwa, Przemysław [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Perkowski, Krzysztof [Department of Nanotechnology, Institute of Ceramics and Building Materials, Postępu 9, 02-676 Warsaw (Poland); Zasada, Dariusz [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Kobus, Izabela; Konopka, Gustaw [Department of Nanotechnology, Institute of Ceramics and Building Materials, Postępu 9, 02-676 Warsaw (Poland); Czujko, Tomasz [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Varin, Robert A., E-mail: robert.varin@uwaterloo.ca [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave., Waterloo, ON N2L 3G1 (Canada)

    2016-07-25

    The Fe–Cr–Ti-Nb elemental powders were mechanically alloyed/ball milled with TiB{sub 2} and a small quantity of Y{sub 2}O{sub 3} ceramic to synthesize a novel Fe-based alloy-ceramic powder composite that could be processed by hot isostatic pressing (HIP) for a perceived potential application as a neutron absorber in nuclear reactors. After ball milling for the 30–80 h duration relatively uniform powders with micrometric sizes were produced. With increasing milling time a fraction of TiB{sub 2} particles became covered with the much softer Fe-based alloy which resulted in the formation of a characteristic “core-mantel” structure. For the final HIP-ing process the mechanically alloyed powders were initially uniaxially pressed into rod-shaped compacts and then cold isostatically pressed (CIP-ed). Subsequently, the rod-shaped compacts were placed in the Ti-tubing and subjected to hot isostatic pressing (HIP) at 1150 °C/200 MPa pressure. The HIP-ing process resulted in the formation of the near-Ti and intermediate diffusional layers in the microstructure of HIP-ed samples which formed in accord with the Fe-Ti binary phase diagram. Those layers contain the phases such as α-Ti (HCP), the FeTi intermetallic and their hypo-eutectoid mixtures. In addition, needle-like particles were formed in both layers in accord with the Ti-B binary phase diagram. Nanohardness testing, using a Berkovich type diamond tip, shows that the nanohardness in the intermediate layer areas, corresponding to the composition of the hypo-eutectoid mixture of Ti-FeTi, equals 980.0 (±27.1) HV and correspondingly 1176.9 (±47.6) HV for the FeTi phase. The nanohardness in the sample's center in the areas with the fine mixture of Fe-based alloy and small TiB{sub 2} particles equals 1048.3 (±201.8) HV. The average microhardness of samples HIP-ed from powders milled for 30 and 80 h is 588 HV and 733 HV, respectively. - Highlights: • A Fe–Cr–Nb-based composite with TiB{sub 2} neutron

  7. Feasibility study of 24-month cycle using enriched Gadolinium as burnable poison for OPR1000

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Sang-Rae; Shin, Ho-Cheol [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    All of cobalt-60 sources are imported to Korea. CANDU units are generally used to produce cobalt-60 at Bruce and Point Lepreau in Canada and Embalse in Argentina. China has started production of cobalt-60 using its CANDU 6 Qinshan Phase III nuclear power plant in 2009. For cobalt-60 production, the reactor's full complement of stainless steel adjusters is replaced with neutronically equivalent cobalt-59 adjusters, which are essentially invisible to reactor operation. With its very high neutron flux and optimized fuel burn-up, the CANDU has a very high cobalt-60 production rate in a relatively short time. This makes CANDU an excellent vehicle for bulk cobalt-60 production. Several studies have been performed to produce cobalt-60 using adjuster rod at Wolsong nuclear power plant. This study proposed new concept for producing cobalt-60 and performed the feasibility study. Bundle typed cobalt loading concept is proposed and evaluated the feasibility to fuel management without physics and system design change. The requirement to load cobalt bundle to the core was considered and several channels are nominated. The production of cobalt-60 source is very depend on the flux level and burnup directly.

  8. Electrochemical Corrosion Testing of Neutron Absorber Materials

    Energy Technology Data Exchange (ETDEWEB)

    Tedd Lister; Ron Mizia; Arnold Erickson; Tammy Trowbridge

    2007-05-01

    This report summarizes the results of crevice-corrosion tests for six alloys in solutions representative of ionic compositions inside the Yucca Mountain waste package should a breech occur. The alloys in these tests are Neutronit A978a (ingot metallurgy, hot rolled), Neutrosorb Plus 304B4 Grade Ab (powder metallurgy, hot rolled), Neutrosorb Plus 304B5 Grade Ab (powder metallurgy, hot rolled), Neutrosorb Plus 304B6 Grade Ab (powder metallurgy, hot rolled), Ni-Cr-Mo-Gd alloy2 (ingot metallurgy, hot rolled), and Alloy 22 (ingot metallurgy, hot rolled).

  9. Effect of Burnable Absorbers on Inert Matrix Fuel Performance and Transuranic Burnup in a Low Power Density Light-Water Reactor

    Directory of Open Access Journals (Sweden)

    Geoff Recktenwald

    2013-04-01

    Full Text Available Zirconium dioxide has received particular attention as a fuel matrix because of its ability to form a solid solution with transuranic elements, natural radiation stability and desirable mechanical properties. However, zirconium dioxide has a lower coefficient of thermal conductivity than uranium dioxide and this presents an obstacle to the deployment of these fuels in commercial reactors. Here we show that axial doping of a zirconium dioxide based fuel with erbium reduces power peaking and fuel temperature. Full core simulations of a modified AP1000 core were done using MCNPX 2.7.0. The inert matrix fuel contained 15 w/o transuranics at its beginning of life and constituted 28% of the assemblies in the core. Axial doping reduced power peaking at startup by more than ~23% in the axial direction and reduced the peak to average power within the core from 1.80 to 1.44. The core was able to remain critical between refueling while running at a simulated 2000 MWth on an 18 month refueling cycle. The results show that the reactor would maintain negative core average reactivity and void coefficients during operation. This type of fuel cycle would reduce the overall production of transuranics in a pressurized water reactor by 86%.

  10. Neutronic characteristics of an OTTO refueling PBMR

    Energy Technology Data Exchange (ETDEWEB)

    Tran, Hoai Nam, E-mail: nam@nephy.chalmers.se [Chalmers University of Technology, Department of Applied Physics, Division of Nuclear Engineering, SE-412 96 Gothenburg (Sweden); Hoang, Van Khanh [Institute for Nuclear Science and Technology, 179 Hoang Quoc Viet str., Hanoi (Viet Nam)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Neutronic characteristics were analyzed for an OTTO refueling PBMR. Black-Right-Pointing-Pointer The core uses newly designed fuel pebbles with Gd{sub 2}O{sub 3} as burnable poison. Black-Right-Pointing-Pointer The neutronic characteristics are comparable with a reference multi-pass scheme. Black-Right-Pointing-Pointer The average discharged burnup is 21% lower than that of the multi-pass scheme. - Abstract: Neutronic characteristics were investigated for a once-through-then-out (OTTO) refueling scheme based on the 400 MWt pebble bed modular reactor (PBMR) and compared with that of a reference multi-pass scheme. The core was loaded with new fuel pebbles which were designed with Gd{sub 2}O{sub 3} particles to flatten the axial power profile. The Gd{sub 2}O{sub 3} design was considered in a multi-parameter optimization to maximize the average discharged burnup while maintaining a limited power peak and ensuring core criticality. The results show that the OTTO scheme using the new fuel pebbles can achieve the maximum average discharged burnup of about 75 GWd/t, at which the core neutronic characteristics are comparable with that of the reference multi-pass scheme. This means that the efficiency of fuel utilization of the OTTO scheme is about 21% less than that of the multi-pass scheme (95 GWd/t).

  11. Gd/sub 2/O/sub 3/ up to 9 weight percent, an established burnable poison for advanced fuel management in pressurized water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, W.; Kiehlmann, H.D.; Neufert, A.; Peehs, M.

    1987-07-01

    High weight percent Gd/sub 2/O/sub 3/ has given excellent results when applied as burnable poison in pressurized water reactors for advanced fuel management tasks. Poisoning of up to 9 weight% Gd/sub 2/O/sub 3/ has been implemented in commercial reload cores to match the requirements of full low leakage loading and cycle extension strategies. Operational performance has confirmed that the high degree of accuracy achieved for calculational methods for standard loading applications also applies for highly Gd poisoned cores. The UO/sub 2/-Gd/sub 2/O/sub 3/ fabrication process has been rationalized by the use of direct pelletizing.

  12. Influence of the neutron transport tube on neutron resonance densitometry

    Directory of Open Access Journals (Sweden)

    Kitatani Fumito

    2017-01-01

    Full Text Available Neutron Resonance Densitometry (NRD is a non-destructive assay technique of nuclear materials in particle-like debris that contains various materials. An aim of NRD is to quantify nuclear materials in a melting fuel of Fukusima Daiichi plant, spent nuclear fuel and annihilation disposal fuel etc. NRD consists of two techniques of Neutron Resonance Transmission Analysis (NRTA and Neutron Resonance Capture Analysis (NRCA or Prompt Gamma-ray Analysis (PGA. A density of nuclear material isotopes is decided with NRTA. The materials absorbing a neutron in a wide energy range such as boron in a sample are identified by NRCA/PGA. The information of NRCA/PGA is used in NRTA analysis to quantify nuclear material isotopes. A neutron time of flight (TOF method is used in NRD measurements. A facility, consisting of a neutron source, a neutron flight path, and a detector is required. A short flight path and a strong neutron source are needed to downsize such a facility and put NRD into practical use. A neutron transport tube covers a flight path to prevent noises. In order to investigate the effect of neutron transport tube and pulse width of a neutron source, we carried out NRTA experiments with a 2-m short neutron transport tube constructed at Kyoto University Research Reactor Institute - Linear Accelerator (KURRI-LINAC, and impacts of shield of neutron transport tube and influence of pulse width of a neutron source were examined. A shield of the neutron transport tube reduced a background and had a good influence on the measurement. The resonance dips of 183W at 27 eV was successfully observed with a pulse width of a neutron source less than 2 μs.

  13. Compilation of Existing Neutron Screen Technology

    Directory of Open Access Journals (Sweden)

    N. Chrysanthopoulou

    2014-01-01

    Full Text Available The presence of fast neutron spectra in new reactors is expected to induce a strong impact on the contained materials, including structural materials, nuclear fuels, neutron reflecting materials, and tritium breeding materials. Therefore, introduction of these reactors into operation will require extensive testing of their components, which must be performed under neutronic conditions representative of those expected to prevail inside the reactor cores when in operation. Due to limited availability of fast reactors, testing of future reactor materials will mostly take place in water cooled material test reactors (MTRs by tailoring the neutron spectrum via neutron screens. The latter rely on the utilization of materials capable of absorbing neutrons at specific energy. A large but fragmented experience is available on that topic. In this work a comprehensive compilation of the existing neutron screen technology is attempted, focusing on neutron screens developed in order to locally enhance the fast over thermal neutron flux ratio in a reactor core.

  14. Composite absorbing potentials

    CERN Document Server

    Palao, J P; Sala, P R

    1998-01-01

    The multiple scattering interferences due to the addition of several contiguous potential units are used to construct composite absorbing potentials that absorb at an arbitrary set of incident momenta or for a broad momentum interval.

  15. The ALICE absorbers

    CERN Multimedia

    Maximilien Brice

    2006-01-01

    Weighing more than 400 tonnes, the ALICE absorbers and the surrounding support structures have been installed and aligned with a precision of 1-2 mm, hardly an easy task but a very important one. The ALICE absorbers are made of three parts: the front absorber, a 35-tonne cone-shaped structure, and two small-angle absorbers, long straight cylinder sections weighing 18 and 40 tonnes. The three pieces lined up have a total length of about 17 m.

  16. Radiation shielding for neutron guides

    Science.gov (United States)

    Ersez, T.; Braoudakis, G.; Osborn, J. C.

    2006-11-01

    Models of the neutron guide shielding for the out of bunker guides on the thermal and cold neutron beam lines of the OPAL Reactor (ANSTO) were constructed using the Monte Carlo code MCNP 4B. The neutrons that were not reflected inside the guides but were absorbed by the supermirror (SM) layers were noted to be a significant source of gammas. Gammas also arise from neutrons absorbed by the B, Si, Na and K contained in the glass. The proposed shielding design has produced compact shielding assemblies. These arrangements are consistent with safety requirements, floor load limits, and cost constraints. To verify the design a prototype was assembled consisting of 120 mm thick Pb(96%)Sb(4%) walls resting on a concrete block. There was good agreement between experimental measurements and calculated dose rates for bulk shield regions.

  17. Ion chamber based neutron detectors

    Science.gov (United States)

    Derzon, Mark S; Galambos, Paul C; Renzi, Ronald F

    2014-12-16

    A neutron detector with monolithically integrated readout circuitry, including: a bonded semiconductor die; an ion chamber formed in the bonded semiconductor die; a first electrode and a second electrode formed in the ion chamber; a neutron absorbing material filling the ion chamber; and the readout circuitry which is electrically coupled to the first and second electrodes. The bonded semiconductor die includes an etched semiconductor substrate bonded to an active semiconductor substrate. The readout circuitry is formed in a portion of the active semiconductor substrate. The ion chamber has a substantially planar first surface on which the first electrode is formed and a substantially planar second surface, parallel to the first surface, on which the second electrode is formed. The distance between the first electrode and the second electrode may be equal to or less than the 50% attenuation length for neutrons in the neutron absorbing material filling the ion chamber.

  18. Neutron-beam-shaping assembly for boron neutron-capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Zaidi, L. [University of Science and Technology Houari Boumediene (Algeria); Kashaeva, E. A. [Zababakhin All-Russian Scientific Research Institute for Technical Physics (VNIITF) (Russian Federation); Lezhnin, S. I. [Russian Academy of Sciences, Novosibirsk Branch, Nuclear Safety Institute (Russian Federation); Malyshkin, G. N.; Samarin, S. I. [Zababakhin All-Russian Scientific Research Institute for Technical Physics (VNIITF) (Russian Federation); Sycheva, T. V. [Russian Academy of Sciences, Budker Institute of Nuclear Physics, Siberian Branch (Russian Federation); Taskaev, S. Yu., E-mail: taskaev@inp.nsk.su [Novosibirsk State University (Russian Federation); Frolov, S. A. [Zababakhin All-Russian Scientific Research Institute for Technical Physics (VNIITF) (Russian Federation)

    2017-01-15

    A neutron-beam-shaping assembly consisting of a moderator, a reflector, and an absorber is used to form a therapeutic neutron beam for the boron neutron-capture therapy of malignant tumors at accelerator neutron sources. A new structure of the moderator and reflector is proposed in the present article, and the results of a numerical simulation of the neutron spectrum and of the absorbed dose in a modified Snyder head phantom are presented. The application of a composite moderator and of a composite reflector and the implementation of neutron production at the proton energy of 2.3MeV are shown to permit obtaining a high-quality therapeutic neutron beam.

  19. MeV Neutron Production from Thermal Neutron Capture in {6}^Li Simulated with Geant4

    CERN Document Server

    Santoro, Valentina; Bentley, Phillip M

    2015-01-01

    Various Li compounds are commonly used at neutron facilities as neutron absorbers. These compounds provide one of the highest ratios of neutron attenuation to $\\gamma$-ray production. Unfortunately, the usage of these compounds can also give rise to fast neutron emission with energies up to almost 16 MeV. Historically, some details in this fast neutron production mechanism can be absent from some modeling packages under some optimization scenarios. In this work, we tested Geant4 to assess the performance of this simulation toolkit for the fast neutron generation mechanism. We compare the results of simulations performed with Geant4 to available measurements. The outcome of our study shows that results of the Geant4 simulations are in good agreement with the available measurements for $^6$Li fast neutron production, and suitable for neutron instrument background evaluation at spallation neutron sources.

  20. MeV Neutron Production from Thermal Neutron Capture in 6Li Simulated With Geant4

    Science.gov (United States)

    Santoro, Valentina; DiJulio, Douglas D.; Bentley, Phillip M.

    2016-09-01

    Various Li compounds are commonly used at neutron facilities as neutron absorbers. These compounds provide one of the highest ratios of neutron attenuation to y- ray production. Unfortunately, the usage of these compounds can also give rise to fast neutron emission with energies up to almost 16 MeV. Historically, some details in this fast neutron production mechanism can be absent from some modeling packages under some optimization scenarios. In this work, we tested Geant4 to assess the performance of this simulation toolkit for the fast neutron generation mechanism. We compare the results of simulations performed with Geant4 to available measurements. The outcome of our study shows that results of the Geant4 simulations are in good agreement with the available measurements for 6 Li fast neutron production, and suitable for neutron instrument background evaluation at spallation neutron sources.

  1. Neutron dosimetry in solid water phantom

    Energy Technology Data Exchange (ETDEWEB)

    Benites-Rengifo, Jorge Luis, E-mail: jlbenitesr@prodigy.net.mx [Centro Estatal de Cancerologia de Nayarit, Calzada de la Cruz 118 Sur, Tepic Nayarit, Mexico and Instituto Tecnico Superior de Radiologia, ITEC, Calle Leon 129, Tepic Nayarit (Mexico); Vega-Carrillo, Hector Rene, E-mail: fermineutron@yahoo.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Apdo. postal 336, 98000, Zacatecas, Zac. (Mexico)

    2014-11-07

    The neutron spectra, the Kerma and the absorbed dose due to neutrons were estimated along the incoming beam in a solid water phantom. Calculations were carried out with the MCNP5 code, where the bunker, the phantom and the model of the15 MV LINAC head were modeled. As the incoming beam goes into the phantom the neutron spectrum is modified and the dosimetric values are reduced.

  2. Degradation analysis of neutrons absorber bars Ag-In-Cd. Part 2: corrosion behaviour and reactor water contamination; Analise da degradacao de barras absorvedoras de neutrons de Ag-In.Cd. Parte 2: comportamento quanto a corrosao e contaminacao da agua do reator

    Energy Technology Data Exchange (ETDEWEB)

    Castanheira, Myrthes; Terremoto, Luis Antonio A.; Silva, Jose Eduardo Rosa da; Zeituni, Carlos Alberto [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Centro de Engenharia Nuclear

    2002-07-01

    Analyzing the Ni plated Ag-In-Cd absorber bars degradation behavior under irradiation, this work reports a qualitative assessment of the IEA-R1 absorber bars degradation current condition by viewpoint of alloy and Ni clad corrosion, and about the reactor water contamination as a complement of visual inspections results carried out at 1998, 2000 and 2001 whose had pointed to visible degree of degradation accumulated along 29 years of operation in the reactor. (author)

  3. Contribution of recoil atoms to irradiation damage in absorber materials

    Science.gov (United States)

    Simeone, D.; Hablot, O.; Micalet, V.; Bellon, P.; Serruys, Y.

    1997-08-01

    Absorbing materials are used to control the reactivity of nuclear reactors by taking advantage of nuclear reactions (e.g., 10B(n,α) 7Li) where neutrons are absorbed. During such reactions, energetic recoils are produced. As a result, radiation damage in absorbing materials originates both from these nuclear reactions and from elastic collisions between neutrons and atoms. This damage eventually leads to a partial destruction of the materials, and this is the main limitation on their lifetime in nuclear reactors. Using a formalism developed to calculate displacements per atoms (dpa) in a multi atomic target, we have calculated damages in terms of displacements per atom in a (n,α) absorbing material taking into account geometrical effects of 10 boron self shielding and transmutation reactions induced by neutrons inside the absorber. Radiation damage is calculated for boron carbide and hafnium diboride ceramics in a Pressurized Water Reactor environment. It is shown that recoils produced by nuclear reactions account for the main part of the radiation damage created in these ceramics. Damages are calculated as a function of the distance from the center of an absorber pellet. Due to the self-shielding effect, these damage curves exhibit sharp maxima, the position of which changes in time.

  4. Absorbing Outflows in AGN

    Science.gov (United States)

    Mathur, Smita

    2002-01-01

    The goal of this program was a comprehensive multiwavelength study of absorption phenomena in active galactic nuclei (AGN). These include a variety of associated absorption systems: X-ray warm absorbers, X-ray cold absorbers. UV absorbers with high ionization lines, MgII absorbers, red quasars and BALQSOs. The aim is to determine the physical conditions in the absorbing outflows, study their inter-relations and their role in AGN. We designed several observing programs to achieve this goal: X-ray spectroscopy, UV spectroscopy, FLAY spectroscopy and X-ray imaging. We were very successful towards achieving the goal over the five year period as shown through following observing programs and papers. Copies of a few papers are attached with this report.

  5. Neutron resonance parameters of dysprosium isotopes using neutron capture yields

    Energy Technology Data Exchange (ETDEWEB)

    Shin, S. G.; Kye, Y. U.; Cho, M. H. [POSTECH, Pohang (Korea, Republic of); Namkung, W. [Pohang Accelerator Laboratory, Pohang (Korea, Republic of); Kim, G. N. [Kyungpook National University, Daegu (Korea, Republic of); Lee, M. W.; Kang, Y. R. [Dongnam Inst. Of Radiological and Medical Science, Busan (Korea, Republic of)

    2015-10-15

    Dysprosium is used in the field of nuclear reactor system because it has a very large thermal neutron absorption cross-section. The dysprosium alloyed with special stainless steels is attractive for control in nuclear reactor because of the ability to absorb neutrons readily without swelling or contracting over time and its high melting point. Dysprosium is also one of fission products from the thermal fission of {sup 234}U, {sup 233}U, and {sup 239}Pu. The fission products are accumulated in the reactor core by the burn-up of the nuclear fuel and the poison effect is increased. Therefore, it is required to understand how Dysprosium as both a poison and an absorbing material in the control rod has an effect on the neutron population in a nuclear reactor system over all energy regions. Neutron Capture experiments on Dy isotopes were performed at the electron linear accelerator (LINAC) facility of the Rensselear Polytechnic Institute (RPI) in the neutron energy region from 10 eV to 1 keV. Resonance parameters were extracted by fitting the neutron capture data using the SAMMY multilevel R-matrix Bayesian code.

  6. Neutron imaging of radioactive sources

    Science.gov (United States)

    Hameed, F.; Karimzadeh, S.; Zawisky, M.

    2008-08-01

    Isotopic neutron sources have been available for more than six decades. At the Atomic Institute in Vienna, operating a 250 kW TRIGA reactor, different neutron sources are in use for instrument calibration and fast neutron applications but we have only little information about their construction and densities. The knowledge of source design is essential for a complete MCNP5 modeling of the experiments. Neutron radiography (NR) and neutron tomography (NT) are the best choices for the non-destructive inspection of the source geometry and homogeneity. From the transmission analysis we gain information about the shielding components and the densities of the radio-isotopes in the cores. Three neutron sources, based on (alpha, n) reaction, have been investigated, two 239PuBe sources and one 241AmBe source. In the NR images the internal structure was clearly revealed using high-resolving scintillation and imaging plate detectors. In one source tablet a crack was detected which causes asymmetric neutron emission. The tomography inspection of strong absorbing materials is more challenging due to the low beam intensity of 1.3x105 n/cm2s at our NT instrument, and due to the beam hardening effect which requires an extension of reconstruction software. The tomographic inspection of a PuBe neutron source and appropriate measures for background and beam hardening correction are presented.

  7. Neutron Repulsion

    OpenAIRE

    Manuel, Oliver K.

    2011-01-01

    Earth is connected gravitationally, magnetically and electrically to its heat source - a neutron star that is obscured from view by waste products in the photosphere. Neutron repulsion is like the hot filament in an incandescent light bulb. Excited neutrons are emitted from the solar core and decay into hydrogen that glows in the photosphere like a frosted light bulb. Neutron repulsion was recognized in nuclear rest mass data in 2000 as the overlooked source of energy, the keystone of an arch...

  8. "m=1" coatings for neutron guides

    OpenAIRE

    Cooper-Jensen, C.P.; Vorobiev, A.; Klinkby, Esben Bryndt; Kapaklis, V.; Wilkens, H.; Rats, D.; Hjörvarsson, B.; Kirstein, O.; Bentley, Philip

    2014-01-01

    A substantial part of the price for a neutron guide is the shielding needed because of the gamma ray produced when neutrons are absorbed. This absorption occurs in the coating and the substrate of the neutron guides. Traditional m=1 coatings have been made of Ni and if reflectivity over the critical angle of Ni is needed one has used Ni58 or Ni/Ti multilayer coatings. Ni has one of the highest neutron scattering density but it also has a fairly high absorption cross section for cold and therm...

  9. Multiband terahertz metamaterial absorber

    Institute of Scientific and Technical Information of China (English)

    Gu Chao; Qu Shao-Bo; Pei Zhi-Bin; Xu Zhuo; Liu Jia; Gu Wei

    2011-01-01

    This paper reports the design of a multiband metamaterial (MM) absorber in the terahertz region. Theoretical and simulated results show that the absorber has four distinct and strong absorption points at 1.69, 2.76, 3.41 and that the impedance of MM could be tuned to match approximately the impedance of the free space to minimise the reflectance at absorption frequencies and large power loss exists at absorption frequencies. The distribution of the power loss indicates that the absorber is an excellent electromagnetic wave collector: the wave is first trapped and reinforced in certain specific locations and then consumed. This multiband absorber has applications in the detection of explosives and materials characterisation.

  10. TOMS Absorbing Aerosol Index

    Data.gov (United States)

    Washington University St Louis — TOMS_AI_G is an aerosol related dataset derived from the Total Ozone Monitoring Satellite (TOMS) Sensor. The TOMS aerosol index arises from absorbing aerosols such...

  11. Electrodynamic absorber theory

    OpenAIRE

    Deckert, Dirk-André

    2010-01-01

    This work deals with questions that arise in classical and quantum electrodynamics when describing the phenomena of radiation reaction and pair creation. The two guiding ideas are the absorber idea of Wheeler and Feynman (i.e. all emitted radiation will be again be absorbed by matter) and the electron sea idea of Dirac. In the first part classical dynamics are studied which allow for a description of radiation reaction without the need of renormalization. The starting point are the couple...

  12. Improved safety fast reactor with “reservoir” for delayed neutrons generating

    Science.gov (United States)

    Kulikov, G. G.; Apse, V. A.; Shmelev, A. N.; Kulikov, E. G.

    2017-01-01

    The paper considers the possibility to improve safety of fast reactors by using weak neutron absorber with large atomic weight as a material for external neutron reflector and for internal cavity in the reactor core (the neutron “reservoir”) where generation of some additional “delayed” neutron takes place. The effects produced by the external neutron reflector and the internal neutron “reservoir” on kinetic behavior of fast reactors are inter-compared. It is demonstrated that neutron kinetics of fast reactors with such external and internal zones becomes the quieter as compared with neutron kinetics of thermal reactors.

  13. Neutron Radiography

    Science.gov (United States)

    Heller, A. K.; Brenizer, J. S.

    Neutron radiography and its related two-dimensional (2D) neutron imaging techniques have been established as invaluable nondestructive inspection methods and quantitative measurement tools. They have been used in a wide variety of applications ranging from inspection of aircraft engine turbine blades to study of two-phase fluid flow in operating proton exchange membrane fuel cells. Neutron radiography is similar to X-ray radiography in that the method produces a 2D attenuation map of neutron radiation that has penetrated the object being examined. However, the images produced differ and are often complementary due to the differences between X-ray and neutron interaction mechanisms. The uses and types of 2D neutron imaging have expanded over the past 15 years as a result of advances in imaging technology and improvements in neutron generators/sources and computers. Still, high-intensity sources such as those from reactors and spallation neutron sources, together with conventional film radiography, remain the mainstay of high-resolution, large field-of-view neutron imaging. This chapter presents a summary of the history, methods, and related variations of neutron radiography techniques.

  14. Unidirectional perfect absorber

    Science.gov (United States)

    Jin, L.; Wang, P.; Song, Z.

    2016-09-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices.

  15. Metasurface Broadband Solar Absorber

    CERN Document Server

    Azad, A K; Sykora, M; Weisse-Bernstein, N R; Luk, T S; Taylor, A J; Dalvit, D A R; Chen, H -T

    2015-01-01

    We demonstrate a broadband, polarization independent, omnidirectional absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low emissivity at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. Furthermore, we discuss the potential use of our metasurface absorber design in solar thermophotovoltaics by exploiting refractory plasmonic materials.

  16. Fusion neutronics

    CERN Document Server

    Wu, Yican

    2017-01-01

    This book provides a systematic and comprehensive introduction to fusion neutronics, covering all key topics from the fundamental theories and methodologies, as well as a wide range of fusion system designs and experiments. It is the first-ever book focusing on the subject of fusion neutronics research. Compared with other nuclear devices such as fission reactors and accelerators, fusion systems are normally characterized by their complex geometry and nuclear physics, which entail new challenges for neutronics such as complicated modeling, deep penetration, low simulation efficiency, multi-physics coupling, etc. The book focuses on the neutronics characteristics of fusion systems and introduces a series of theories and methodologies that were developed to address the challenges of fusion neutronics, and which have since been widely applied all over the world. Further, it introduces readers to neutronics design’s unique principles and procedures, experimental methodologies and technologies for fusion systems...

  17. Neutron Albedo

    CERN Document Server

    Ignatovich, V K

    2005-01-01

    A new, algebraic, method is applied to calculation of neutron albedo from substance to check the claim that use of ultradispersive fuel and moderator of an active core can help to gain in size and mass of the reactor. In a model of isotropic distribution of incident and reflected neutrons it is shown that coherent scattering on separate grains in the case of thermal neutrons increases transport cross section negligibly, however it decreases albedo from a wall of finite thickness because of decrease of substance density. A visible increase of albedo takes place only for neutrons with wave length of the order of the size of a single grain.

  18. Fast Neutron Dosimeter for the Space Environment Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Secondary neutrons make a significant contribution to the total absorbed dose received by space crews during long duration space missions However, only a limited...

  19. Simulations of a PSD Plastic Neutron Collar for Assaying Fresh Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Hausladen, Paul [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Newby, Jason [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McElroy, Robert Dennis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-11-01

    The potential performance of a notional active coincidence collar for assaying uranium fuel based on segmented detectors constructed from the new PSD plastic fast organic scintillator with pulse shape discrimination capability was investigated in simulation. Like the International Atomic Energy Agency s present Uranium Neutron Collar for LEU (UNCL), the PSD plastic collar would also function by stimulating fission in the 235U content of the fuel with a moderated 241Am/Li neutron source and detecting instances of induced fission via neutron coincidence counting. In contrast to the moderated detectors of the UNCL, the fast time scale of detection in the scintillator eliminates statistical errors due to accidental coincidences that limit the performance of the UNCL. However, the potential to detect a single neutron multiple times historically has been one of the properties of organic scintillator detectors that has prevented their adoption for international safeguards applications. Consequently, as part of the analysis of simulated data, a method was developed by which true neutron-neutron coincidences can be distinguished from inter-detector scatter that takes advantage of the position and timing resolution of segmented detectors. Then, the performance of the notional simulated coincidence collar was evaluated for assaying a variety of fresh fuels, including some containing burnable poisons and partial defects. In these simulations, particular attention was paid to the analysis of fast mode measurements. In fast mode, a Cd liner is placed inside the collar to shield the fuel from the interrogating source and detector moderators, thereby eliminating the thermal neutron flux that is most sensitive to the presence of burnable poisons that are ubiquitous in modern nuclear fuels. The simulations indicate that the predicted precision of fast mode measurements is similar to what can be achieved by the present UNCL in thermal mode. For example, the statistical accuracy of a

  20. Solar concentrator/absorber

    Science.gov (United States)

    Von Tiesenhausen, G. F.

    1976-01-01

    Collector/energy converter, consisting of dual-slope optical concentrator and counterflow thermal energy absorber, is attached to multiaxis support structure. Efficient over wide range of illumination levels, device may be used to generate high temperature steam, serve as solar powered dryer, or power absorption cycle cooler.

  1. Neutron dosimetry; Dosimetria de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Fratin, Luciano

    1993-12-31

    A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq {sup 241} Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s{sup -1} and 0,5 {sup {mu}}Sv s{sup -1}. A calibrated 50 nSv s{sup -1} thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the {sup 241} Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold {sup 241} Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,{alpha}) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kV{sub pp} cm{sup -1}, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46{+-} 0,09) 10{sup 4} tracks cm{sup -2} mSv{sup -1} for thermal neutrons, (9{+-}3) 10{sup 2} tracks cm{sup -2} mSV{sup -1} for intermediate neutrons and (26{+-}4) tracks cm{sup -2} mSv{sup -1} for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990`s ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is

  2. Neutron reflectometry

    DEFF Research Database (Denmark)

    Klösgen-Buchkremer, Beate Maria

    2014-01-01

    films or films with magnetic properties. The reason is the peculiar property of neutron light since the mass of a neutron is close to the one of a proton, and since it bears a magnetic moment. The optical properties of matter, when interacting with neutrons, are described by a refractive index......Neutron (and X-ray) reflectometry constitute complementary interfacially sensitive techniques that open access to studying the structure within thin films of both soft and hard condensed matter. Film thickness starts oxide surfaces on bulk substrates, proceeding to (pauci-)molecular layers and up...... to hundreds of nanometers. Thickness resolution for flat surfaces is in the range of few Ǻngstrøm, and as a peculiar benefit, the presence and properties of buried interfaces are accessible. Focus here will be on neutron reflectometry, a technique that is unique in applications involving composite organic...

  3. THE INFLUENCE OF CaO AND P2O5 OF BONE ASH UPON THE REACTIVITY AND THE BURNABILITY OF CEMENT RAW MIXTURES

    Directory of Open Access Journals (Sweden)

    TOMÁŠ IFKA

    2012-03-01

    Full Text Available The influence of CaO and P2O5 upon the reactivity of cement raw meal was investigated in this paper. Ash of bone meal containing Ca3(PO42 - 3CaO·P2O5 was used as the source of P2O5. Two series of samples with different content of the ash of bone meal were prepared. In the first series, the ash of bone was added into cement raw meal. The second series of samples were prepared by considering ash as one of CaO sources. Therefore, the total content of CaO in cement raw meal was kept constant, while the amount of P2O5 increased. These different series of samples were investigated by analyzing free lime content in the clinkers. The XRD analysis and Electron Micro Probe Analyzer analysis of the clinkers were also carried out. Two parameters were used to characterize the reactivity of cement raw meal: content of free lime and Burnability Index (BI calculated from free lime content in both series of samples burnt at 1350 ºC, 1400 ºC, 1450 ºC and 1500 ºC. According to the first parameter, P2O5 content that drastically makes worse the reactivity of cement raw meal was found at 1.11 wt.% in the first series, while this limit has reached 1.52 wt.% in the second one. According to the BI, the limit of P2O5 was found at 1.42 wt. % in the first series and 1, 61 wt.% in the second one. Furthermore, EPMA has demonstrated the presence of P2O5 in both calcium silicate phases forming thus solid solutions.

  4. Implementing in vasion neutron capture therapy (INCT) using capillary neutron optical systems (CNOS) assessment

    Science.gov (United States)

    Borisov, G. I.; Kumakhov, M. A.; Kondratenko, R. I.; Spryshkova, R. A.

    2005-07-01

    During LNCT the exposed object represents a practically ideal trap for neutrons In this instance, the number of neutrons that entered the object through the inlet hole is equal to the number of nuclear reactions of their absorption. Using this model and nuclear data about all considered nuclides for a biological tissue, the following INCT characteristics were theoretically calculated with regard to introduction of dosage-forming preparations based on different concentrations of lOB, l57Gd and 235U nuclides: - effective masses irradiated by thermal neutrons, - energies absorbed in the object for one thermal neutron entered, - partial content of basic dosage-forming reactions, - partial content of absorbed dosage of thermal neutrons from basic dosage-forming reactions, - quantity of thermal neutrons needed to create a total absorbed dosage of 5 Gr within the focal spot area of 0,28 cm2, - number of nuclear reactions with dosage-forming nuclides of preparations per one cell based on the cell volume of 7x7x7 m. It follows from the data obtained that dosage-forming nuclide 10B is not only the optimal but also the only one suitable for INCT. Using the obtained outcome, one can assess parameters of capillary neutron optical systems (CNOS) that are pre-requisite to implement INCT at particular experimental channels (EC) of research nuclear reactors.

  5. Optimal Sound Absorbing Structures

    CERN Document Server

    Yang, Min; Fu, Caixing; Sheng, Ping

    2016-01-01

    Causal nature of the acoustic response, for any materials or structures, dictates an inequality that relates the absorption spectrum of the sample to its thickness. We present a general recipe for constructing sound-absorbing structures that can attain near-equality for the causal relation with very high absorption performance; such structures are denoted optimal. Our strategy involves using carefully designed acoustic metamaterials as backing to a thin layer of conventional sound absorbing material, e.g., acoustic sponge. By using this design approach, we have realized a 12 cm-thick structure that exhibits broadband, near-perfect flat absorption spectrum starting at around 400 Hz. From the causal relation, the calculated minimum sample thickness is 11.5 cm for the observed absorption spectrum. We present the theory that underlies such absorption performance, involving the evanescent waves and their interaction with a dissipative medium, and show the excellent agreement with the experiment.

  6. Universal metamaterial absorbe

    CERN Document Server

    Smaali, Rafik; Moreau, Antoine; Taliercio, Thierry; Centeno, Emmanuel

    2016-01-01

    We propose a design for an universal absorber, characterized by a resonance frequency that can be tuned from visible to microwave frequencies independently of the choice of the metal and the dielectrics involved. An almost resonant perfect absorption up to 99.8 % is demonstrated at resonance for all polarization states of light and for a very wide angular aperture. These properties originate from a magnetic Fabry-Perot mode that is confined in a dielectric spacer of $\\lambda/100$ thickness by a metamaterial layer and a mirror. An extraordinary large funneling through nano-slits explains how light can be trapped in the structure. Simple scaling laws can be used as a recipe to design ultra-thin perfect absorbers whatever the materials and the desired resonance wavelength, making our design truly universal.

  7. Cooling neutrons using non-dispersive magnetic excitations

    CERN Document Server

    Zimmer, Oliver

    2014-01-01

    A new method is proposed for cooling neutrons by inelastic magnetic scattering in weakly absorbing, cold paramagnetic systems. Kinetic neutron energy is removed in constant decrements determined by the Zeeman energy of paramagnetic atoms or ions in an external magnetic field, or by zero-field level splittings in magnetic molecules. Analytical solutions of the stationary neutron transport equation are given using inelastic neutron scattering cross sections derived in an appendix. They neglect any inelastic process except the paramagnetic scattering and hence still underestimate very-cold neutron densities. Molecular oxygen with its triplet ground state appears particularly promising, notably as a host in fully deuterated oxygen-clathrate hydrate, or more exotically, in dry oxygen-He4 van der Waals clusters. At a neutron temperature about 6 K, for which neutron conversion to ultra-cold neutrons by single-phonon emission in pure superfluid He4 works best, conversion rates due to paramagnetic scattering in the cl...

  8. Absorbable and biodegradable polymers

    CERN Document Server

    Shalaby, Shalaby W

    2003-01-01

    INTRODUCTION NOTES: Absorbable/Biodegradable Polymers: Technology Evolution. DEVELOPMENT AND APPLICATIONOF NEW SYSTEMS: Segmented Copolyesters with Prolonged Strength Retention Profiles. Polyaxial Crystalline Fiber-Forming Copolyester. Polyethylene Glycol-Based Copolyesters. Cyanoacrylate-Based Systems as Tissue Adhesives. Chitosan-Based Systems. Hyaluronic Acid-Based Systems. DEVELOPMENTS IN PREPARATIVE, PROCESSING, AND EVALUATION METHODS: New Approaches to the Synthesis of Crystalline. Fiber-Forming Aliphatic Copolyesters. Advances in Morphological Development to Tailor the Performance of Me

  9. Ionized Absorbers in AGN

    Science.gov (United States)

    Mathur, S.

    1999-01-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  10. Clustering of Absorbers

    CERN Document Server

    Cristiani, S; D'Odorico, V; Fontana, A; Giallongo, E; Moscardini, L; Savaglio, S

    1997-01-01

    The observed clustering of Lyman-$\\alpha$ lines is reviewed and compared with the clustering of CIV systems. We argue that a continuity of properties exists between Lyman-$\\alpha$ and metal systems and show that the small-scale clustering of the absorbers is consistent with a scenario of gravitationally induced correlations. At large scales statistically significant over and under-densities (including voids) are found on scales of tens of Mpc.

  11. Metamaterial Absorbers in Terahertz Band

    Institute of Scientific and Technical Information of China (English)

    Qi-Ye Wen; Huai-Wu Zhang; Qing-Hui Yang; Man-Man Mo

    2013-01-01

    In recent years, a great deal of effort has been made to a create terahertz (THz) wave absorber based on metamaterials (MM). Metamaterials absorbers have a variety of potential applications including thermal emitters, detector, stealth technology, phase imaging, etc. In this paper, we firstly introduce the basic structure and work principle of the THz MM absorbers, and a transmission line model is developed for devices analysis. To expand the application of THz absorbers, dual-band and broadband THz MM absorbers are designed, fabricated, and measured. At the end of this article, the future development trends of MM absorbers are discussed.

  12. Theory of microslit absorbers

    Institute of Scientific and Technical Information of China (English)

    MAA Dah-You

    2001-01-01

    It is well known that narrow slit may be used as acoustical element. The exact formulae of the acoustical impedance of a narrow slit and its low-frequency approximation are available. The theory of slit is extended and a simple and practical formula is derived for the single slit. It is found that the resistance-to-reactance ratio of the slit increases to larger than one when the slit width is decreased to submillimeter range, and a panel with extremely narrow slits plus a back cavity will make an absorber with good absorption in a wide frequency range,without any porous or fibrous material. A complete theory of the microslit absorber (MSA) is, thus, presented and its absorption characteristics discussed. It is found that the MSA has essentially the same formulae as the microperforate absorber (MPA), except that the numerical coefficient of the resistance is smaller and the end correction for the mass reactance is larger for the MSA, resulting a performance inferior to that of MPA, ordinarily. Measures are proposed to compensate for these.

  13. Emesis ED50 of Neutron Irradiation and Prophylactic Effectiveness.

    Science.gov (United States)

    1985-08-01

    Gamma rays were aximized by thermalizing neutrons in 30.5 cm (12 in.) of water, then absorbing the thermal eutrons in a gadolinium-cadmium shield. The...12 in.) from the tank protrusion in exposure room 1. The neu- tron component was minimized by thermalization of the neutrons by the 30.5 cm (12 in...of water between the core and the exposure room. The thermalized neutrons were subsequently captured in the gadolinium-cadmium on the tank wall. The

  14. Test Measurements On A Resonance Filter Spectrometer Using Electronvolt Neutrons

    OpenAIRE

    Newport, Robert J.; Seeger, P. A.; Williams, W. G.

    1985-01-01

    Inelastic neutron scattering measurements carried out on a prototype spectrometer at the WNR pulsed neutron facility are presented. Energy transfers are determined by differencing time-of-flight spectra taken with and without absorbing foils containing sharp nuclear resonances which define the scattered neutron energy. The quality of the spectra are enhanced by i) applying a double difference technique to improve line shape and ii) using fixed incident and scattered beam filters which discrim...

  15. Neutron-scattering study of the vibrational behavior of trehalose aqueous solutions

    CERN Document Server

    Branca, C; Migliardo, F; Romeo, G; Villari, V; Wanderlingh, U; Colognesi, D

    2002-01-01

    Neutron spectra for hydrated trehalose samples have been obtained by using the time-of-flight spectrometer TOSCA at the ISIS Pulse Neutron Facility (Rutherford Appleton Laboratory, Chilton, UK). Neutron spectra have been compared to the absorbance spectra obtained by Fourier-transform infrared spectroscopy. Finally, a comparison with findings obtained by density functional theory has been performed. 3 Refs.

  16. Aluminum-titanium hydride-boron carbide composite provides lightweight neutron shield material

    Science.gov (United States)

    Poindexter, A. M.

    1967-01-01

    Inexpensive lightweight neutron shield material has high strength and ductility and withstands high internal heat generation rates without excessive thermal stress. This composite material combines structural and thermal properties of aluminum, neutron moderating properties of titanium hydride, and neutron absorbing characteristics of boron carbide.

  17. GT-MHR project high-temperature reactor neutronic issues and ways to resolve them

    Energy Technology Data Exchange (ETDEWEB)

    Sukharev, Yu.P., E-mail: sukharev@okbm.nnov.ru [JSC “Afrikantov OKBM”, 15 Burnakovsky Projezd, Nizhny Novgorod (Russian Federation); Fomichenko, P.A., E-mail: pf@dhtp.kiae.ru [National Research Center “Kurchatov Institute”, 1 Kurchatov Square, Moscow (Russian Federation)

    2014-05-01

    The scope and trends of analytical and experimental activities aimed at studying neutronic characteristics of the GT-MHR high-temperature gas-cooled reactor are determined in compliance with the requirement for reliable validation of the GT-MHR design applying certified software tools. Risk factor existing in analytical validation of the GT-MHR neutronic characteristics consists in that the applicable neutronic analysis codes, which have been used up to the present time, are aimed at the HTGR designing and they have been tested mostly within analytical and experimental studies of HTGR with uranium fuel. Therefore, at the early stages of the GT-MHR nuclear design development it has already been determined that the experiments should be performed using critical test facilities and analytical benchmark-studies which are becoming quite relevant considering that plutonium fuel and erbium burnable poison are used. The report contains the validation program of the GT-MHR neutronic properties, the stages of its implementation and the main results obtained by now.

  18. Neutronic density perturbation by probes; Pertubacion de densidades neutronicas por sondas

    Energy Technology Data Exchange (ETDEWEB)

    Vigon, M. A.; Diez, L.

    1956-07-01

    The introduction of absorbent materials of neutrons in diffuser media, produces local disturbances of neutronic density. The disturbance depends especially on the nature and size of the absorbent. Approximated equations which relates te disturbance and the distance to the absorbent in the case of thin disks have been drawn. The experimental comprobation has been carried out in two especial cases. In both cases the experimental results are in agreement with the calculated values from these equations. (Author)

  19. Absorber for terahertz radiation management

    Science.gov (United States)

    Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

    2015-12-08

    A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

  20. A Perfect Terahertz Metamaterial Absorber

    CERN Document Server

    Bagheri, Alireza

    2015-01-01

    In this paper the design for an absorbing metamaterial with near unity absorbance in terahertz region is presented. The absorber's unit cell structure consists of two metamaterial resonators that couple to electric and magnetic fields separately. The structure allows us to maximize absorption by varying dielectric material and thickness and, hence the effective electrical permittivity and magnetic permeability.

  1. Sensing with THz metamaterial absorbers

    CERN Document Server

    Cong, Longqing

    2014-01-01

    Metamaterial perfect absorbers from microwaves to optical part of the electromagnetic spectrum has been intensely studied for its ability to absorb electromagnetic radiation. Perfect absorption of light by metamaterials have opened up new opportunities for application oriented functionalities such as efficient sensors and emitters. We present an absorber based sensing scheme at the terahertz frequencies and discuss optimized designs to achieve high frequency and amplitude sensitivities. The major advantage of a perfect metamaterial absorber as a sensor is the sensitive shift in the absorber resonance frequency along with the sharp change in the amplitude of the resonance due to strong interaction of the analyte with the electric and the magnetic fields at resonant perfect absorption frequency. We compare the sensing performance of the perfect metamaterial absorber with its complementary structural design and planar metasurface with identical structure. The best FoM values obtained for the absorber sensor here...

  2. Neutron production from beam-modifying devices in a modern double scattering proton therapy beam delivery system.

    Science.gov (United States)

    Pérez-Andújar, Angélica; Newhauser, Wayne D; Deluca, Paul M

    2009-02-21

    In this work the neutron production in a passive beam delivery system was investigated. Secondary particles including neutrons are created as the proton beam interacts with beam shaping devices in the treatment head. Stray neutron exposure to the whole body may increase the risk that the patient develops a radiogenic cancer years or decades after radiotherapy. We simulated a passive proton beam delivery system with double scattering technology to determine the neutron production and energy distribution at 200 MeV proton energy. Specifically, we studied the neutron absorbed dose per therapeutic absorbed dose, the neutron absorbed dose per source particle and the neutron energy spectrum at various locations around the nozzle. We also investigated the neutron production along the nozzle's central axis. The absorbed doses and neutron spectra were simulated with the MCNPX Monte Carlo code. The simulations revealed that the range modulation wheel (RMW) is the most intense neutron source of any of the beam spreading devices within the nozzle. This finding suggests that it may be helpful to refine the design of the RMW assembly, e.g., by adding local shielding, to suppress neutron-induced damage to components in the nozzle and to reduce the shielding thickness of the treatment vault. The simulations also revealed that the neutron dose to the patient is predominated by neutrons produced in the field defining collimator assembly, located just upstream of the patient.

  3. Neutron Repulsion

    CERN Document Server

    Manuel, Oliver K

    2011-01-01

    Earth is connected gravitationally, magnetically and electrically to its heat source - a neutron star that is obscured from view by waste products in the photosphere. Neutron repulsion is like the hot filament in an incandescent light bulb. Excited neutrons are emitted from the solar core and decay into hydrogen that glows in the photosphere like a frosted light bulb. Neutron repulsion was recognized in nuclear rest mass data in 2000 as the overlooked source of energy, the keystone of an arch that locked together these puzzling space-age observations: 1.) Excess 136Xe accompanied primordial helium in the stellar debris that formed the solar system (Fig. 1); 2.) The Sun formed on the supernova core (Fig. 2); 3.) Waste products from the core pass through an iron-rich mantle, selectively carrying lighter elements and lighter isotopes of each element into the photosphere (Figs. 3-4); and 4.) Neutron repulsion powers the Sun and sustains life (Figs. 5-7). Together these findings offer a framework for understanding...

  4. Ferroelectrics based absorbing layers

    Science.gov (United States)

    Hao, Jianping; Sadaune, Véronique; Burgnies, Ludovic; Lippens, Didier

    2014-07-01

    We show that ferroelectrics-based periodic structure made of BaSrTiO3 (BST) cubes, arrayed onto a metal plate with a thin dielectric spacer film exhibit a dramatic enhancement of absorbance with value close to unity. The enhancement is found around the Mie magnetic resonance of the Ferroelectrics cubes with the backside metal layer stopping any transmitted waves. It also involves quasi-perfect impedance matching resulting in reflection suppression via simultaneous magnetic and electrical activities. In addition, it was shown numerically the existence of a periodicity optimum, which is explained from surface waves analysis along with trade-off between the resonance damping and the intrinsic loss of ferroelectrics cubes. An experimental verification in a hollow waveguide configuration with a good comparison with full-wave numerical modelling is at last reported by measuring the scattering parameters of single and dual BST cubes schemes pointing out coupling effects for densely packed structures.

  5. The Flexible Bass Absorber

    DEFF Research Database (Denmark)

    Adelman-Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian

    2007-01-01

    Multi-purpose concert halls face a dilemma. They host different performance types that require significantly different acoustic conditions in order to provide the best sound quality to both the performers, sound engineers and the audience. Pop and rock music often contain high levels of bass soun...... has been developed. Measurements were made on a variable and mobile low-frequency absorber. The paper presents the results of prototype sound absorption measurements as well as elements of the design.......Multi-purpose concert halls face a dilemma. They host different performance types that require significantly different acoustic conditions in order to provide the best sound quality to both the performers, sound engineers and the audience. Pop and rock music often contain high levels of bass sound...

  6. The Flexible Bass Absorber

    DEFF Research Database (Denmark)

    Adelman-Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian

    2007-01-01

    Multi-purpose concert halls face a dilemma. They host different performance types that require significantly different acoustic conditions in order to provide the best sound quality to both the performers, sound engineers and the audience. Pop and rock music often contains high levels of bass sou...... has been developed. Measurements were made on a variable and mobile low-frequency absorber. The paper presents the results of prototype sound absorption measurements as well as elements of the design.......Multi-purpose concert halls face a dilemma. They host different performance types that require significantly different acoustic conditions in order to provide the best sound quality to both the performers, sound engineers and the audience. Pop and rock music often contains high levels of bass sound...

  7. Neutron imaging — Detector options in progress

    Science.gov (United States)

    Lehmann, E. H.; Tremsin, A.; Grünzweig, C.; Johnson, I.; Boillat, P.; Josic, L.

    2011-01-01

    system was tested successfully at PSI and other neutron imaging facilities. Other options might be to use MEDIPIX devices with neutron absorbing/converting materials. A similar pixel detector, EIGER, has been developed recently at PSI and its performance in the field of neutron imaging is under investigation. For future applications at the upcoming pulsed spallation sources the time = energy resolving aspect becomes even more important. This will push the future use of pixilated systems. This article intends to describe the present state-of-the-art even if most of the presented results are obtained at PSI's leading facilities, sometimes in collaboration with our partners.

  8. Development of time projection chamber for precise neutron lifetime measurement using pulsed cold neutron beams

    CERN Document Server

    Arimoto, Y; Igarashi, Y; Iwashita, Y; Ino, T; Katayama, R; Kitahara, R; Kitaguchi, M; Matsumura, H; Mishima, K; Oide, H; Otono, H; Sakakibara, R; Shima, T; Shimizu, H M; Sugino, T; Sumi, N; Sumino, H; Taketani, K; Tanaka, G; Tanaka, M; Tauchi, K; Toyoda, A; Yamada, T; Yamashita, S; Yokoyama, H; Yoshioka, T

    2015-01-01

    A new time projection chamber (TPC) was developed for neutron lifetime measurement using a pulsed cold neutron spallation source at the Japan Proton Accelerator Research Complex (J-PARC). Managing considerable background events from natural sources and the beam radioactivity is a challenging aspect of this measurement. To overcome this problem, the developed TPC has unprecedented features such as the use of polyether-ether-ketone plates in the support structure and internal surfaces covered with $^6$Li-enriched tiles to absorb outlier neutrons. In this paper, the design and performance of the new TPC are reported in detail.

  9. Development of time projection chamber for precise neutron lifetime measurement using pulsed cold neutron beams

    Energy Technology Data Exchange (ETDEWEB)

    Arimoto, Y. [High Energy Accelerator Research Organization, Ibaraki (Japan); Higashi, N. [Graduate School of Science, University of Tokyo, Tokyo (Japan); Igarashi, Y. [High Energy Accelerator Research Organization, Ibaraki (Japan); Iwashita, Y. [Institute for Chemical Research, Kyoto University, Kyoto (Japan); Ino, T. [High Energy Accelerator Research Organization, Ibaraki (Japan); Katayama, R. [Graduate School of Science, University of Tokyo, Tokyo (Japan); Kitaguchi, M. [Kobayashi-Maskawa Institute, Nagoya University, Aichi (Japan); Kitahara, R. [Graduate School of Science, Kyoto University, Kyoto (Japan); Matsumura, H.; Mishima, K. [High Energy Accelerator Research Organization, Ibaraki (Japan); Nagakura, N.; Oide, H. [Graduate School of Science, University of Tokyo, Tokyo (Japan); Otono, H., E-mail: otono@phys.kyushu-u.ac.jp [Research Centre for Advanced Particle Physics, Kyushu University, Fukuoka (Japan); Sakakibara, R. [Department of Physics, Nagoya University, Aichi (Japan); Shima, T. [Research Center for Nuclear Physics, Osaka University, Osaka (Japan); Shimizu, H.M.; Sugino, T. [Department of Physics, Nagoya University, Aichi (Japan); Sumi, N. [Faculty of Sciences, Kyushu University, Fukuoka (Japan); Sumino, H. [Department of Basic Science, University of Tokyo, Tokyo (Japan); Taketani, K. [High Energy Accelerator Research Organization, Ibaraki (Japan); and others

    2015-11-01

    A new time projection chamber (TPC) was developed for neutron lifetime measurement using a pulsed cold neutron spallation source at the Japan Proton Accelerator Research Complex (J-PARC). Managing considerable background events from natural sources and the beam radioactivity is a challenging aspect of this measurement. To overcome this problem, the developed TPC has unprecedented features such as the use of polyether-ether-ketone plates in the support structure and internal surfaces covered with {sup 6}Li-enriched tiles to absorb outlier neutrons. In this paper, the design and performance of the new TPC are reported in detail.

  10. Neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Heger, G. [Rheinisch-Westfaelische Technische Hochschule Aachen, Inst. fuer Kristallographie, Aachen (Germany)

    1996-12-31

    X-ray diffraction using conventional laboratory equipment and/or synchrotron installations is the most important method for structure analyses. The purpose of this paper is to discuss special cases, for which, in addition to this indispensable part, neutrons are required to solve structural problems. Even though the huge intensity of modern synchrotron sources allows in principle the study of magnetic X-ray scattering the investigation of magnetic structures is still one of the most important applications of neutron diffraction. (author) 15 figs., 1 tab., 10 refs.

  11. Liquid Hydrogen Absorber for MICE

    Energy Technology Data Exchange (ETDEWEB)

    Ishimoto, S.; Suzuki, S.; Yoshida, M.; Green, Michael A.; Kuno, Y.; Lau, Wing

    2010-05-30

    Liquid hydrogen absorbers for the Muon Ionization Cooling Experiment (MICE) have been developed, and the first absorber has been tested at KEK. In the preliminary test at KEK we have successfully filled the absorber with {approx}2 liters of liquid hydrogen. The measured hydrogen condensation speed was 2.5 liters/day at 1.0 bar. No hydrogen leakage to vacuum was found between 300 K and 20 K. The MICE experiment includes three AFC (absorber focusing coil) modules, each containing a 21 liter liquid hydrogen absorber made of aluminum. The AFC module has safety windows to separate its vacuum from that of neighboring modules. Liquid hydrogen is supplied from a cryocooler with cooling power 1.5 W at 4.2 K. The first absorber will be assembled in the AFC module and installed in MICE at RAL.

  12. Neutronics of pulsed spallation neutron sources

    CERN Document Server

    Watanabe, N

    2003-01-01

    Various topics and issues on the neutronics of pulsed spallation neutron sources, mainly for neutron scattering experiments, are reviewed to give a wide circle of readers a better understanding of these sources in order to achieve a high neutronic performance. Starting from what neutrons are needed, what the spallation reaction is and how to produce slow-neutrons more efficiently, the outline of the target and moderator neutronics are explained. Various efforts with some new concepts or ideas have already been devoted to obtaining the highest possible slow-neutron intensity with desired pulse characteristics. This paper also reviews the recent progress of such efforts, mainly focused on moderator neutronics, since moderators are the final devices of a neutron source, which determine the source performance. Various governing parameters for neutron-pulse characteristics such as material issues, geometrical parameters (shape and dimensions), the target-moderator coupling scheme, the ortho-para-hydrogen ratio, po...

  13. Evaluation of an iron-filtered epithermal neutron beam for neutron-capture therapy.

    Science.gov (United States)

    Musolino, S V; McGinley, P H; Greenwood, R C; Kliauga, P; Fairchild, R G

    1991-01-01

    An epithermal neutron filter using iron, aluminum, and sulfur was evaluated to determine if the therapeutic performance could be improved with respect to aluminum-sulfur-based filters. An empirically optimized filter was developed that delivered a 93% pure beam of 24-keV epithermal neutrons. It was expected that a thick filter using iron with a density thickness greater than 200 g/cm2 would eliminate the excess gamma contamination found in Al-S filters. This research showed that prompt gamma production from neutron interactions in iron was the dominant dose component. Dosimetric parameters of the beam were determined from the measurement of absorbed dose in air, thermal neutron flux in a head phantom, neutron and gamma spectroscopy, and microdosimetry.

  14. A new scintillating-fiber-array neutron detector

    CERN Document Server

    Zhang Qi; Xie Zhong Shen; Cao Jin Yun; Niu Shen Gli; Ouyang Xia Opin

    2002-01-01

    A new scintillating-fiber-array neutron detector has been developed. The detector consists of a bee-hive-shaped lead absorber, a scintillating fiber array, a light guide, a filter and a photomultiplier tube. The experimental results show that the new detector's neuron-to-gamma sensitivity ratio is improved about six times compared to traditional plastic scintillation detectors to 2.5 MeV neutrons and 1.25 MeV gamma rays. Hence, the detector should be very useful in the measurements of pulsed neutrons from fission reactions in a neutron-gamma mixed field.

  15. High efficiency proportional neutron detector with solid liner internal structures

    Science.gov (United States)

    Kisner, Roger Allen; Holcomb, David Eugene; Brown, Gilbert M.

    2014-08-05

    A tube-style neutron detector, a panel-style neutron detector incorporating a plurality of tube-style neutron detectors, and a panel-style neutron detector including a plurality of anode wires are provided. A plurality of channels is provided in a neutron detector such that each channel has an inner surface of a coating layer including a neutron-absorbing material. A wire anode is provided at end of each channel so that electrons generated by a charged daughter particle generated by a neutron are collected to detect a neutron-matter interaction. Moderator units can be incorporated into a neutron detector to provide improved detection efficiencies and/or to determine neutron energy spectrum. Gas-based proportional response from the neutron detectors can be employed for special nuclear material (SNM) detection. This neutron detector can provide similar performance to .sup.3He-based detectors without requiring .sup.3He and without containing toxic, flammable, or high-pressure materials.

  16. Development of high-intensity deuterium-deuterium and deuterium-trittium neutron sources and neutron filters for medical and industrial applications

    Science.gov (United States)

    Verbeke, Jerome Maurice

    This thesis consists of three main parts. The first part is related to boron neutron capture therapy (BNCT), the second part to boron neutron capture synovectomy (BNCS), and the third part to the neutron generator development. A monoenergetic neutron beam simulation study is carried out to determine the most suitable neutron energy for treatment of shallow and deep-seated brain tumors in the context of BNCT. Two figures-of-merit---the absorbed skin dose and the absorbed tumor dose at a given depth in the brain---are used to measure the neutron beam quality. Based on the results of this study, moderators, reflectors and delimiters are designed and optimized to moderate the high-energy neutrons from the fusion reactions D-D and D-T down to a suitable energy spectrum. Two different computational models have been used to study the dose distribution in the brain. A monoenergetic neutron beam simulation study is carried out to determine the optimal neutron energy for treatment of rheumatoid arthritis. Two figures-of-merit are used to measure the neutron beam quality, the ratio of the synovium absorbed dose to the skin absorbed dose, and the ratio of the synovium absorbed dose to the bone absorbed dose. It was found that thermal neutron beams are optimal for treatment. Computation of the dose distribution in the knee requires the simulation of particle transport from the neutron source to the knee phantom through the moderator. The third part describes the development of high-intensity D-D and D-T neutron generators. Thick target neutron yield computations have been performed to estimate the neutron yield of titanium and scandium targets. With an average deuteron beam current of 1 A and an energy of 120 keV, a neutron production of about 1014 n/s can be estimated for a tritiated target. In mixed deuteron/triton beam operation, a beam current of 2 A at 150 keV is required for the same neutron output. Despite this lower neutron production, this mode of operation is

  17. Evaluation of Neutron Response of Criticality Accident Alarm System Detector to Quasi-Monoenergetic 24 keV Neutrons

    Science.gov (United States)

    Tsujimura, Norio; Yoshida, Tadayoshi; Yashima, Hiroshi

    The criticality accident alarm system (CAAS), which was recently developed and installed at the Japan Atomic Energy Agency's Tokai Reprocessing Plant, consists of a plastic scintillator combined with a cadmium-lined polyethylene moderator and thereby responds to both neutrons and gamma rays. To evaluate the neutron absorbed dose rate response of the CAAS detector, a 24 keV quasi-monoenergetic neutron irradiation experiment was performed at the B-1 facility of the Kyoto University Research Reactor. The detector's evaluated neutron response was confirmed to agree reasonably well with prior computer-predicted responses.

  18. Electro neutrons around a 12 MV Linac

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Apdo. Postal 336, 98000 Zacatecas (Mexico); Perez L, L. H., E-mail: fermineutron@yahoo.com [Instituto Zacatecano del Tumor, A. C., Lago de la Encantada No. 294, Fracc. Lomas del Lago, Zacatecas (Mexico)

    2012-10-15

    Neutron contamination around Linacs for radiotherapy is a source of undesirable doses for the patient. The main source of these neutrons is the photonuclear reactions occurring in the Linac head and the patient body. Electrons also produce neutrons through (e, en) reactions. This reaction is known as electro disintegration and is carried out by the electron scattering that produce a virtual photon that is absorbed by the scattering nucleus producing the reaction e + A {yields} (A-1) + n + e'. In this work the electron-neutron spectrum to 100 cm from the isocenter of a 12 MV Linac has been measured using a passive Bonner spheres spectrometer in a novel procedure named Planetary mode. (Author)

  19. Neutron tomography

    Science.gov (United States)

    Crump, James C., III; Richards, Wade J.; Shields, Kevin C.

    1995-07-01

    The McClellan Nuclear Radiation Center's (MNRC) staff in conjunction with a Cooperative Research and Development Agreement (CRDA) with the U.C. Santa Barbara facility has developed a system that can be used for aircraft inspection of jet engine blades. The problem was to develop an inspection system that can detect very low concentrations of hydrogen (i.e., greater than 100 ppm) in metal matricies. Specifically in Titanium alloy jet engine blades. Entrapment and precipitation of hydrogen in metals is an undesirable phenomenon which occurs in many alloys of steel and titanium. In general, metals suffer a loss of mechanical properties after long exposures to hydrogen, especially at high temperatures and pressures, thereby becoming embrittled. Neutron radiography has been used as a nondestructive testing technique for many years. Neutrons, because of their unique interactions with materials, are especially useful in the detection of hydrogen. They have an extremely high interaction cross section for low atomic number nuclei (i.e., hydrogen). Thus hydrogen in a metal matrix can be visualized using neutrons. Traditional radiography is sensitive to the total attenuation integrated over the path of radiation through the material. Increased sensitivity and quantitative cross section resolution can be obtained using three-dimensional volumetric imaging techniques such as tomography. The solution used to solve the problem was to develop a neutron tomography system. The neutron source is the McClellan Nuclear Radiation Center's 1 MW TRIGA reactor. This paper describes the hardware used in the system as well as some of the preliminary results.

  20. Improvement Of The Helmholtz Absorber

    Science.gov (United States)

    Morrow, Duane L.

    1992-01-01

    Helmholtz-resonator system improved to enable it to absorb sound at more than one frequency without appreciable loss of effectiveness at primary frequency. Addition of annular cavities enables absorption of sound at harmonic frequencies in addition to primary frequency. Improved absorber designed for use on structures of high transmission loss. Applied to such machines as fixed-speed engines and fans.

  1. Leaf absorbance and photosynthesis

    Science.gov (United States)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  2. Visible light broadband perfect absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Jia, X. L.; Meng, Q. X.; Yuan, C. X.; Zhou, Z. X.; Wang, X. O., E-mail: wxo@hit.edu.cn [School of Science, Harbin Institute of Technology, Harbin 150001 (China)

    2016-03-15

    The visible light broadband perfect absorbers based on the silver (Ag) nano elliptical disks and holes array are studied using finite difference time domain simulations. The semiconducting indium silicon dioxide thin film is introduced as the space layer in this sandwiched structure. Utilizing the asymmetrical geometry of the structures, polarization sensitivity for transverse electric wave (TE)/transverse magnetic wave (TM) and left circular polarization wave (LCP)/right circular polarization wave (RCP) of the broadband absorption are gained. The absorbers with Ag nano disks and holes array show several peaks absorbance of 100% by numerical simulation. These simple and flexible perfect absorbers are particularly desirable for various potential applications including the solar energy absorber.

  3. On the Rutherford-Santilli neutron model

    Energy Technology Data Exchange (ETDEWEB)

    Burande, Chandrakant S. [Vilasrao Deshmukh College of Engineering and Technology, Mouda, India-441104, Email: csburande@gmail.com (India)

    2015-03-10

    In 1920 H. Rutherford conjectured that the first particle synthesized in stars is neutron from a proton and an electron after which all known matter is progressively synthesized. However, Pauli objected Rutherford’s version of neutron synthesis because inability to represent spin 1/2 of the neutron. Using this objection E. Fermi proposed emission of massless particle, called “neutrino”. However, Santilli has dismissed the neutrino hypothesis following certain ambiguities such as positive binding energy required in synthesis of neutron. He found that celebrated Schrödinger’s equation of quantum physics is not suitable for obtaining positive binding energy for bound state at the dimension of 10{sup −13}cm. In order to remove these shortcomings, Santilli has developed isomathematics and then hadronic mechanics, which allowed the time invariant representation of Hamiltonian and non-Hamiltonian interactions as needed for the neutron synthesis (see for example: References cited at [1]).Thus the anomalies pertaining to the binding energy, the spin and the magnetic moment got resolved. He successfully calculated missing positive binding energy via isonormalization of the mass for electron when totally immersed within the hyper-dense medium inside the proton. Considering Rutherford’s compression of the isoelectron within the proton in the singlet coupling, he also identified the spin 1/2 for neutron and calculated the magnetic moment of the neutron. In order to verify his logical concept, he repeated the Don Carlo Borghi experiment of synthesis of the neutron from proton and electrons and verified that the said setup indeed produces neutron-type particles called “neutroids” which latter is absorbed by the activated detector substances that produces known nuclear reactions. He dismissed the neutrino hypothesis and replaced it with a longitudinal impulse originating from the ether as a universal substratum, named, “etherino”. He pointed out that all the

  4. Improved Determination of the Neutron Lifetime

    CERN Document Server

    Yue, A T; Gilliam, D M; Greene, G L; Laptev, A B; Nico, J S; Snow, W M; Wietfeldt, F E

    2013-01-01

    The most precise determination of the neutron lifetime using the beam method was completed in 2005 and reported a result of tau_n = (886.3 +/- 1.2 [stat] +/- 3.2 [sys]) s. The dominant uncertainties were attributed to the absolute determination of the fluence of the neutron beam (2.7 s). The fluence was measured with a neutron monitor that counted the neutron-induced charged particles from absorption in a thin, well-characterized 6Li deposit. The detection efficiency of the monitor was calculated from the areal density of the deposit, the detector solid angle, and the ENDF/B-VI 6Li(n,t)4He thermal neutron cross section. In the current work, we have measured the detection efficiency of the same monitor used in the neutron lifetime measurement with a second, totally-absorbing neutron detector. This direct approach does not rely on the 6Li(n,t)4He cross section or any other nuclear data. The detection efficiency is consistent with the value used in 2005 but was measured with a precision of 0.057 %, which represe...

  5. Neutron reflectometry

    DEFF Research Database (Denmark)

    Klösgen-Buchkremer, Beate Maria

    2014-01-01

    to hundreds of nanometers. Thickness resolution for flat surfaces is in the range of few Ǻngstrøm, and as a peculiar benefit, the presence and properties of buried interfaces are accessible. Focus here will be on neutron reflectometry, a technique that is unique in applications involving composite organic...... of desired information. In the course, an introduction into the method and an overview on selected instruments at large scale facilities will be presented. Examples will be given that illustrate the potential of the method, mostly based on organic films. Results from the investigation of layered films...... and the detection on nanoscopic roughnesses will be shown. The potential of neutron reflectometry is not only of academic origin. It may turn out to be useful in the design and development of new functional materials even though it will never develop into a standard method to be applied in the product control...

  6. Absorbent product to absorb fluids. [for collection of human wastes

    Science.gov (United States)

    Dawn, F. S.; Correale, J. V. (Inventor)

    1982-01-01

    A multi-layer absorbent product for use in contact with the skin to absorb fluids is discussed. The product utilizes a water pervious facing layer for contacting the skin, overlayed by a first fibrous wicking layer, the wicking layer preferably being of the one-way variety in which fluid or liquid is moved away from the facing layer. The product further includes a first container section defined by inner and outer layer of a water pervious wicking material between which is disposed a first absorbent mass. A second container section defined by inner and outer layers between which is disposed a second absorbent mass and a liquid impermeable/gas permeable layer. Spacesuit applications are discussed.

  7. Acoustic performance of membrane absorbers

    Science.gov (United States)

    Frommhold, W.; Fuchs, H. V.; Sheng, S.

    1994-03-01

    This paper is a report on the acoustic properties of absorbing elements, which consist of metal membranes and show good sound absorption at low and medium frequencies over more than one octave. The studies refer to the sound absorption coefficient and acoustic impedance at normal incidence of the sound waves. It is shown that the behavior of the absorbing element is mainly determined by a combination of Helmholtz resonance and plate resonance. The parameters of the separate resonators are determined both by theory and experiment and serve as input data for a simplified calculation model, which can be used as an auxiliary tool for designing membrane absorber silencers.

  8. An introduction to absorbent dressings.

    Science.gov (United States)

    Jones, Menna Lloyd

    2014-12-01

    Exudate bathes the wound bed with a serous fluid that contains essential components that promote wound healing. However, excess exudate is often seen as a challenge for clinicians. Absorbent dressings are often used to aid in the management of exudate, with the aim of providing a moist but unmacerated environment. With so many different types of absorbent dressings available today-alongside making a holistic assessment-it is essential that clinicians also have the knowledge and skill to select the most appropriate absorbent dressing for a given patient.

  9. Constraints on Mercury's surface composition from MESSENGER neutron spectrometer data

    Science.gov (United States)

    Riner, M. A.; Lucey, P. G.; McCubbin, F. M.; Taylor, G. J.

    2011-08-01

    The composition of Mercury's surface is poorly known, but the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission has provided a wealth of new data from three flybys. In particular, MESSENGER Neutron Spectrometer (NS) observations reveal a surface enriched in neutron absorbing elements, consistent with interpretations of color and albedo observations suggesting a surface composition enriched in Fe-Mg-Ti oxides. In this study, we have computed the neutron absorption cross sections for all of the available proposed surface compositions of Mercury and evaluated the plausibility of each surface composition based on the neutron absorption cross section observed by MESSENGER. For identified plausible compositions, the implications for the thermal and magmatic evolution of Mercury are discussed. The measured macroscopic neutron absorption cross section of Mercury is inconsistent with a crust formed from partial melting of plausible bulk mantle compositions, flotation in a magma ocean or adiabatic melting of upwelling cumulates during magma ocean overturn. However, the observed neutron absorption is consistent with model compositions of late-stage magma-ocean cumulates and some proposed compositions from spectral modeling and equilibrium modeling. This suggests that the enrichment of neutron absorbing elements may be indicative of the processes that acted to form Mercury's crust. The enrichment in neutron absorbing elements, in combination with spectral observations that constrain FeO in silicates (neutron absorption cross section. High-Fe oxides are not required and more Mg-rich oxides may even be favored as the Ti-contents can sufficiently account for the observed neutron absorption.

  10. Spallation Neutron Source (SNS)

    Data.gov (United States)

    Federal Laboratory Consortium — The SNS at Oak Ridge National Laboratory is a next-generation spallation neutron source for neutron scattering that is currently the most powerful neutron source in...

  11. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

  12. Calculated characteristics of subcritical assembly with anisotropic transport of neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Gorin, N.V.; Lipilina, E.N.; Lyutov, V.D.; Saukov, A.I. [Zababakhin Russian Federal Nuclear Center - All-Russian Scientific Researching Institute of Technical Physics (Russian Federation)

    2003-07-01

    There was considered possibility of creating enough sub-critical system that multiply neutron fluence from a primary source by many orders. For assemblies with high neutron tie between parts, it is impossible. That is why there was developed a construction consisting of many units (cascades) having weak feedback with preceding cascades. The feedback attenuation was obtained placing layers of slow neutron absorber and moderators between the cascades of fission material. Anisotropy of fast neutron transport through the layers was used. The system consisted of many identical cascades aligning one by another. Each cascade consists of layers of moderator, fissile material and absorber of slow neutrons. The calculations were carried out using the code MCNP.4a with nuclear data library ENDF/B5. In this construction neutrons spread predominantly in one direction multiplying in each next fissile layer, and they attenuate considerably in the opposite direction. In a calculated construction, multiplication factor of one cascade is about 1.5 and multiplication factor of whole construction composed of n cascades is 1.5{sup n}. Calculated keff value is 0.9 for one cascade and does not exceed 0.98 for a system containing any number of cascades. Therefore the assembly is always sub-critical and therefore it is safe in respect of criticality. There was considered using such a sub-critical assembly to create a powerful neutron fluence for neutron boron-capturing therapy. The system merits and demerits were discussed. (authors)

  13. Neutron dosimetric measurements in shuttle and MIR.

    Science.gov (United States)

    Reitz, G

    2001-06-01

    Detector packages consisting of thermoluminescence detectors (TLD), nuclear emulsions and plastic track detectors were exposed at identical positions inside MIR space station and on shuttle flights inside Spacelab and Spacehab during different phases of the solar cycle. The objectives of the investigations are to provide data on charge and energy spectra of heavy ions, and the contribution of events with low-energy deposit (protons, electrons, gamma, etc.) to the dose, as well as the contribution of secondaries, such as nuclear disintegration stars and neutrons. For neutron dosimetry 6LiF (TLD600) and 7LiF (TLD700) chips were used both of which have almost the same response to gamma rays but different response to neutrons. Neutrons in space are produced mainly in evaporation and knock-on processes with energies mainly of 1-10 MeV and up to several 100 MeV, respectively. The energy spectrum undergoes continuous changes toward greater depth in the attenuating material until an equilibrium is reached. In equilibrium, the spectrum is a wide continuum extending down to thermal energies to which the 6LiF is sensitive. Based on the difference of absorbed doses in the 6LiF and 7LiF chips, thermal neutron fluxes from 1 to 2.3 cm-2 s-1 are calculated using the assumption that the maximum induced dose in TLD600 for 1 neutron cm-2 is 1.6 x 10(-10) Gy (Horowitz and Freeman, Nucl. Instr. and Meth. 157 (1978) 393). It is assumed that the flux of high-energy neutrons is at least of that quantity. Tissue doses were calculated taking as a mean ambient absorbed dose per neutron 6 x10(-12) Gy cm2 (for a10 MeV neutron). The neutron equivalent doses for the above-mentioned fluxes are 52 micro Gy d-1 and 120 micro Gy d-1. In recent experiments, a personal neutron dosimeter was integrated into the dosimeter packages. First results of this dosimeter which is based on nuclear track detectors with converter foils are reported. For future measurements, a scintillator counter with

  14. Broadband fast semiconductor saturable absorber.

    Science.gov (United States)

    Jacobovitz-Veselka, G R; Kellerm, U; Asom, T

    1992-12-15

    Kerr lens mode-locked (KLM) solid-state lasers are typically not self-starting. We address this problem by introducing a broadband semiconductor saturable absorber that could be used as a tunable, all-solid-state, passive starting mechanism. We extend the wavelength tunability of a semiconductor saturable absorber to more than 100 nm using a band-gap-engineered low-temperature molecular-beam-epitaxy (MBE)-grown bulk AlGaAs semiconductor saturable absorber in which the absorption edge of the saturable absorber has been artificially broadened by continuously reducing the Al concentration during the MBE growth. We demonstrate its tunability and its feasibility as a starting mechanism for KLM with a picosecond resonant passive mode-locked Ti:sapphire laser. The extension to femtosecond KLM lasers has been discussed previously.

  15. Spontaneous emission and absorber theory

    Science.gov (United States)

    Pegg, David T.

    1997-01-01

    One of the long term interests of George Series was the construction of a theory of spontaneous emission which does not involve field quantisation. His approach was written in terms of atomic operators only and he drew a parallel with the Wheeler-Feynman absorber theory of radiation. By making a particular extra postulate, he was able to obtain the correct spontaneous emission rate and the Lamb shift reasonably simply and directly. An examination of his approach indicates that this postulate is physically reasonable and the need for it arises because quantisation in his theory occurs after the response of the absorber has been accounted for by means of the radiative reaction field. We review briefly an alternative absorber theory approach to spontaneous emission based on the direct action between the emitting atom and a quantised absorber, and outline some applications to more recent effects of interest in quantum optics.

  16. Guided tissue regeneration. Absorbable barriers.

    Science.gov (United States)

    Wang, H L; MacNeil, R L

    1998-07-01

    Over the past 15 years, techniques aimed at regeneration of lost periodontal tissue have become widely used and accepted in clinical practice. Among these techniques are those which use the principles of guided tissue regeneration (GTR), wherein barriers (i.e., membranes) are used to control cell and tissue repopulation of the periodontal wound. A variety of non-absorbable and absorbable barriers have been developed and used for this purpose, with a trend in recent years toward increased use of absorbable GTR materials. This article describes the evolution of absorbable barrier materials and overview materials available for clinical use today. In addition, advantages and disadvantages of these materials are discussed, as well as possible new developments in barrier-based GTR therapy.

  17. Test Facility for Volumetric Absorber

    Energy Technology Data Exchange (ETDEWEB)

    Ebert, M.; Dibowski, G.; Pfander, M.; Sack, J. P.; Schwarzbozl, P.; Ulmer, S.

    2006-07-01

    Long-time testing of volumetric absorber modules is an inevitable measure to gain the experience and reliability required for the commercialization of the open volumetric receiver technology. While solar tower test facilities are necessary for performance measurements of complete volumetric receivers, the long-term stability of individual components can be tested in less expensive test setups. For the qualification of the aging effects of operating cycles on single elements of new absorber materials and designs, a test facility was developed and constructed in the framework of the KOSMOSOL project. In order to provide the concentrated solar radiation level, the absorber test facility is integrated into a parabolic dish system at the Plataforma Solar de Almeria (PSA) in Spain. Several new designs of ceramic absorbers were developed and tested during the last months. (Author)

  18. The absorber hypothesis of electrodynamics

    OpenAIRE

    De Luca, Jayme

    2008-01-01

    We test the absorber hypothesis of the action-at-a-distance electrodynamics for globally-bounded solutions of a finite-particle universe. We find that the absorber hypothesis forbids globally-bounded motions for a universe containing only two charged particles, otherwise the condition alone does not forbid globally-bounded motions. We discuss the implication of our results for the various forms of electrodynamics of point charges.

  19. Calculation of thermal neutron self-shielding correction factors for aqueous bulk sample prompt gamma neutron activation analysis using the MCNP code

    Energy Technology Data Exchange (ETDEWEB)

    Nasrabadi, M.N. [Department of Physics, Faculty of Science, University of Kashan, Km. 6, Ravand Road, Kashan (Iran, Islamic Republic of)], E-mail: mnnasri@kashanu.ac.ir; Jalali, M. [Isfahan Nuclear Science and Technology Research Institute, Atomic Energy organization of Iran (Iran, Islamic Republic of); Mohammadi, A. [Department of Physics, Faculty of Science, University of Kashan, Km. 6, Ravand Road, Kashan (Iran, Islamic Republic of)

    2007-10-15

    In this work thermal neutron self-shielding in aqueous bulk samples containing neutron absorbing materials is studied using bulk sample prompt gamma neutron activation analysis (BSPGNAA) with the MCNP code. The code was used to perform three dimensional simulations of a neutron source, neutron detector and sample of various material compositions. The MCNP model was validated against experimental measurements of the neutron flux performed using a BF{sub 3} detector. Simulations were performed to predict thermal neutron self-shielding in aqueous bulk samples containing neutron absorbing solutes. In practice, the MCNP calculations are combined with experimental measurements of the relative thermal neutron flux over the sample's surface, with respect to a reference water sample, to derive the thermal neutron self-shielding within the sample. The proposed methodology can be used for the determination of the elemental concentration of unknown aqueous samples by BSPGNAA where knowledge of the average thermal neutron flux within the sample volume is required.

  20. Neutron Therapy Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Neutron Therapy Facility provides a moderate intensity, broad energy spectrum neutron beam that can be used for short term irradiations for radiobiology (cells)...

  1. Standard specification for nuclear-grade aluminum oxide pellets

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This specification applies to pellets of aluminum oxide that may be ultimately used in a reactor core, for example, as filler or spacers within fuel, burnable poison, or control rods. In order to distinguish between the subject pellets and “burnable poison” pellets, it is established that the subject pellets are not intended to be used as neutron-absorbing material. 1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

  2. Fast and thermal neutron profiles for a 25-MV x-ray beam.

    Science.gov (United States)

    Price, K W; Nath, R; Holeman, G R

    1978-01-01

    High-energy x-ray radiotherapy machines generate neutrons by photonuclear reactions in the target and the treatment head and expose the patient to a neutron flux. In order to evaluate the neutron exposure quantitatively, fast and thermal neutron profiles for 25-MV x-ray beams of the Sagittaire accelerator have been measured. An activation technique, using the reactions 31P(n, gamma)32P (thermal neutrons) and 31P(n, p)31Si (fast neutrons, E greater than 0.7 MeV), has been developed to measure fast- and thermal-neutron fluxes in an intense high-energy photon flux. The sensitivity of this activation detector to high-energy photons, which has plagued many previous neutron measurements, was carefully measured and found to be less than 4%. Neutron fluxes for various photon field sizes ranging from 5 X 5 cm to 30 X 30 cm have been measured. The fast-neutron profiles were observed to have rounded edges and the thermal fluxes were found to be relatively uniform. In the central part of the x-ray beam, the ratio of neutron dose equivalent to photon absorbed dose was found to be between 0.2% and 0.5%. Outside of the photon field, the ratio of neutron dose equivalent to the central-axis photon absorbed dose was 0.12%.

  3. Dysprosium titanate as an absorber material for control rods

    Science.gov (United States)

    Risovany, V. D.; Varlashova, E. E.; Suslov, D. N.

    2000-09-01

    Disprosium titanate is an attractive control rod material for the thermal neutron reactors. Its main advantages are: insignificant swelling, no out-gassing under neutron irradiation, rather high neutron efficiency, a high melting point (˜1870°C), non-interaction with the cladding at temperatures above 1000°C, simple fabrication and easily reprocessed non-radioactive waste. It can be used in control rods as pellets and powder. The disprosium titanate control rods have worked off in the MIR reactor for 17 years, in VVER-1000 - for 4 years without any operating problems. After post-irradiation examinations this type of control rod having high lifetime was recommended for the VVER and RBMK. The paper presents the examination results of absorber element dummies containing dysprosium titanate, irradiated in the SM reactor to the neutron fluence of 3.4×10 22 cm -2 ( E>0.1 MeV) and, also, the data on structure, thermal-physical properties of dysprosium titanate, efficiency of dysprosium titanate control rods.

  4. Dual-sided microstructured semiconductor neutron detectors (DSMSNDs)

    Energy Technology Data Exchange (ETDEWEB)

    Fronk, Ryan G., E-mail: rfronk@ksu.edu [Mechanical and Nuclear Engineering Department, Kansas State University, Manhattan, KS 66506, United States (United States); Bellinger, Steven L.; Henson, Luke C. [Radiation Detection Technologies, Inc., Manhattan, KS 66502 (United States); Ochs, Taylor R.; Smith, Colten T.; Kenneth Shultis, J.; McGregor, Douglas S. [Mechanical and Nuclear Engineering Department, Kansas State University, Manhattan, KS 66506, United States (United States)

    2015-12-21

    Microstructured semiconductor neutron detectors (MSNDs) have in recent years received much interest as high-efficiency replacements for thin-film-coated thermal neutron detectors. The basic device structure of the MSND involves micro-sized trenches that are etched into a vertically-oriented pvn-junction diode that are backfilled with a neutron converting material. Neutrons absorbed within the converting material induce fission of the parent nucleus, producing a pair of energetic charged-particle reaction products that can be counted by the diode. The MSND deep-etched microstructures produce good neutron-absorption and reaction-product counting efficiencies, offering a 10× improvement in intrinsic thermal neutron detection efficiency over thin-film-coated devices. Performance of present-day MSNDs are nearing theoretical limits; streaming paths between the conversion-material backfilled trenches, allow a considerable fraction of neutrons to pass undetected through the device. Dual-sided microstructured semiconductor neutron detectors (DSMSNDs) have been developed that utilize a complementary second set of trenches on the back-side of the device to count streaming neutrons. DSMSND devices are theoretically capable of greater than 80% intrinsic thermal neutron detection efficiency for a 1-mm thick device. The first such prototype DSMSNDs, presented here, have achieved 29.48±0.29% nearly 2× better than MSNDs with similar microstructure dimensions.

  5. Dual-sided microstructured semiconductor neutron detectors (DSMSNDs)

    Science.gov (United States)

    Fronk, Ryan G.; Bellinger, Steven L.; Henson, Luke C.; Ochs, Taylor R.; Smith, Colten T.; Kenneth Shultis, J.; McGregor, Douglas S.

    2015-12-01

    Microstructured semiconductor neutron detectors (MSNDs) have in recent years received much interest as high-efficiency replacements for thin-film-coated thermal neutron detectors. The basic device structure of the MSND involves micro-sized trenches that are etched into a vertically-oriented pvn-junction diode that are backfilled with a neutron converting material. Neutrons absorbed within the converting material induce fission of the parent nucleus, producing a pair of energetic charged-particle reaction products that can be counted by the diode. The MSND deep-etched microstructures produce good neutron-absorption and reaction-product counting efficiencies, offering a 10× improvement in intrinsic thermal neutron detection efficiency over thin-film-coated devices. Performance of present-day MSNDs are nearing theoretical limits; streaming paths between the conversion-material backfilled trenches, allow a considerable fraction of neutrons to pass undetected through the device. Dual-sided microstructured semiconductor neutron detectors (DSMSNDs) have been developed that utilize a complementary second set of trenches on the back-side of the device to count streaming neutrons. DSMSND devices are theoretically capable of greater than 80% intrinsic thermal neutron detection efficiency for a 1-mm thick device. The first such prototype DSMSNDs, presented here, have achieved 29.48±0.29% nearly 2× better than MSNDs with similar microstructure dimensions.

  6. Cell death following thermal neutron exposure

    Energy Technology Data Exchange (ETDEWEB)

    Paterson, L.C. [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada); Atanackovic, J. [Ontario Power Generation, Toronto, Ontario (Canada); Boyer, C. [Canadian Neutron Beam Centre, Chalk River, Ontario (Canada); El-Jaby, S.; Priest, N.D. [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada); Seymour, C.B.; Boreham, D.R. [McMaster Univ., Hamilton, Ontario (Canada); Richardson, R.B. [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2014-07-01

    When individuals are exposed to unknown external ionizing radiation, it is desirable to have the means to assess both the absorbed dose received (Gy) and the radiation quality. Yet, conventional biodosimetry techniques, specifically the dicentric chromosome assay, cannot differentiate between the damage caused by high- and low-linear energy transfer (LET) exposures. Frequencies of apoptosis and necrosis, may provide an alternative method that assesses both the absorbed dose and radiation quality after unknown exposures. For this preliminary study, human lymphocytes were irradiated with {sup 60}Co gamma rays and thermal neutrons. Both apoptosis and necrosis increased with increasing gamma dose. In contrast, no dose-response was observed following thermal neutron exposure at doses up to 2.61 Gy. (author)

  7. Neutron Age Determination in Fast Reactor Materials using the Group Method

    Directory of Open Access Journals (Sweden)

    Kabanova Marina F.

    2016-01-01

    Full Text Available The article deals with the methods of identifying fast neutron age in sodium (Na and uranium-238 (238U; describes the model of advanced and effective fast neutron nuclear reactors (FN, where Na is a coolant while 238U is involved in the fuel cycle in large quantities; justifies the choice of the group method for calculating the neutron age value in the substances mentioned above that can show the accuracy of the used constants for Na and estimate various versions of multilevel description of neutron moderation in 238U – the most powerful resonance absorber of the neutron reactor active zone.

  8. Prediction of in-phantom dose distribution using in-air neutron beam characteristics for BNCS

    Energy Technology Data Exchange (ETDEWEB)

    Verbeke, Jerome M.

    1999-12-14

    A monoenergetic neutron beam simulation study is carried out to determine the optimal neutron energy range for treatment of rheumatoid arthritis using radiation synovectomy. The goal of the treatment is the ablation of diseased synovial membranes in joints, such as knees and fingers. This study focuses on human knee joints. Two figures-of-merit are used to measure the neutron beam quality, the ratio of the synovium absorbed dose to the skin absorbed dose, and the ratio of the synovium absorbed dose to the bone absorbed dose. It was found that (a) thermal neutron beams are optimal for treatment, (b) similar absorbed dose rates and therapeutic ratios are obtained with monodirectional and isotropic neutron beams. Computation of the dose distribution in a human knee requires the simulation of particle transport from the neutron source to the knee phantom through the moderator. A method was developed to predict the dose distribution in a knee phantom from any neutron and photon beam spectra incident on the knee. This method was revealed to be reasonably accurate and enabled one to reduce by a factor of 10 the particle transport simulation time by modeling the moderator only.

  9. ANGRA-1 neutron kinetics model at BOL using WIMSD-5B and PARCS V2.7 codes

    Energy Technology Data Exchange (ETDEWEB)

    Hamers, Adolfo R.; Reis, Patricia A.L.; Rodrigues, Thiago D.A.; Pereira, Claubia; Costa, Antonella L., E-mail: adolforomerohamers@hotmail.com, E-mail: patricialire@yahoo.com.br, E-mail: claubia@nuclear.ufmg.br, E-mail: antonella@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Departamento de Engenheria Nuclear; Miro, R.; Verdu, G., E-mail: rmiro@iqn.upv.es, E-mail: gverdu@iqn.upv.es [Universitat Politecnica de Valencia (Spain)

    2015-07-01

    A steady-state neutron kinetics model of the Angra-1 NPP at BOL (Beginning Of Life) has been developed with the PARCS V2.7 neutron diffusion code. The information of the burnable poison rods, fuel enrichments and control rod banks distributions within the core have been taken from the Angra-1 FSAR (Final Safety Analysis Report) and implemented in the model. The macroscopic cross sections for the fast and thermal neutron groups have been calculated with the WIMSD-5B lattice cell code. The cross sections were obtained for the rodded and unrodded cases for each composition in the core. In order to establish the initial steady-state, an eigenvalue was made with the PARCS V2.7 code for three steady-state scenario cases reported at the FSAR; a K{sub eff} of 1.0733 was obtained for the unrodded case, K{sub eff} of 1.0718 for a 24% of bank D inserted case and K{sub eff} of 0.8512 for the full rodded case. The normalized core power density distributions were obtained and compared with the corresponding FSAR case. (author)

  10. Performance Evaluation of Neutron Absorption Materials with Temperature Change

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hae Sun; Jeong, Hyo Joon; Kim, Eun Han; Han, Moon Hee; Hwang, Won Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Some of these facilities are operated at higher than room temperature, thus the neutron absorption material can be directly affected by the surrounding environment where the temperature is not maintained in a constant condition. Meanwhile, a nucleus in an atom is continuously vibrated with the thermal energy, after which there arises a range of relative speeds between a neutron and the nucleus, even for a fixed neutron speed. At higher temperature, the random motion of the nucleus reproduces new resonance with a lower and broader peak, i.e., Doppler broadening of a resonance, and the capture cross section of neutron is revised. Therefore, the performance of neutron absorption materials may vary with a change of temperature. In this study, the absorption abilities of three kinds of neutron absorbers generally used in the reactor core were analyzed at a range of temperatures from 293.6K to 584K. As a result, the neutron absorption abilities for B{sup 4}C and Ag-In-Cd do not vary with the change of temperature, while that for Gd{sup 2}O{sup 3} absorbers was shown to be decreased approximately 3% with reference to that at 293.6K in the temperature range between the 293.6K and 584K. This phenomenon of the Gd{sup 2}O{sup 3} absorber seems to be caused by the Doppler broadening of the neutron absorption cross-section. Therefore, it is expected that the effect of material temperature on the neutron absorption performance is needed to be considered in the design of nuclear reactor and the analysis of radiation shielding.

  11. Novel Boron Based Multilayer Thermal Neutron Detector

    CERN Document Server

    SCHIEBER, M

    2010-01-01

    The detector contains four or more layers of natural Boron absorbing thermal neutrons. Thickness of a layer is 0.4 - 1.2 mg/cm2. The layers are deposited on one or on both sides of a metal surface used as contacts. Between the absorbing layers there are gas-filled gaps 3 - 6 mm thick. Electric field of 100 - 200 V/cm is applied to the gas-filled gaps. Natural Boron contains almost 20% of 10B isotope. When atoms of 10B capture a thermal neutron, nuclear reaction occurs, as a result of which two heavy particles - alpha particle and ion 7Li - from the thin absorber layer are emitted in opposing sides. One of the two particles penetrates into gas-filled gap between Boron layers and ionizes the gas. An impulse of electric current is created in the gas-filled gap actuated by the applied electric field. The impulse is registered by an electronic circuit. We have made and tested detectors containing from two to sixteen layers of natural Boron with an efficiency of thermal neutron registration from 2.9% to 12.5% accor...

  12. Carbon Absorber Retrofit Equipment (CARE)

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Eric [Neumann Systems Group, Incorporated, Colorado Springs, CO (United States)

    2015-12-23

    During Project DE-FE0007528, CARE (Carbon Absorber Retrofit Equipment), Neumann Systems Group (NSG) designed, installed and tested a 0.5MW NeuStream® carbon dioxide (CO2) capture system using the patented NeuStream® absorber equipment and concentrated (6 molal) piperazine (PZ) as the solvent at Colorado Springs Utilities’ (CSU’s) Martin Drake pulverized coal (PC) power plant. The 36 month project included design, build and test phases. The 0.5MW NeuStream® CO2 capture system was successfully tested on flue gas from both coal and natural gas combustion sources and was shown to meet project objectives. Ninety percent CO2 removal was achieved with greater than 95% CO2product purity. The absorbers tested support a 90% reduction in absorber volume compared to packed towers and with an absorber parasitic power of less than 1% when configured for operation with a 550MW coal plant. The preliminary techno-economic analysis (TEA) performed by the Energy and Environmental Research Center (EERC) predicted an over-the-fence cost of $25.73/tonne of CO2 captured from a sub-critical PC plant.

  13. Mushroom plasmonic metamaterial infrared absorbers

    Science.gov (United States)

    Ogawa, Shinpei; Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-01

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF2 etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  14. Mushroom plasmonic metamaterial infrared absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Shinpei, E-mail: Ogawa.Shimpei@eb.MitsubishiElectric.co.jp; Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji [Advanced Technology R and D Center, Mitsubishi Electric Corporation, 8-1-1 Tsukaguchi-Honmachi, Amagasaki, Hyogo 661-8661 (Japan); Kimata, Masafumi [College of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577 (Japan)

    2015-01-26

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF{sub 2} etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  15. Iodine neutron capture therapy

    Science.gov (United States)

    Ahmed, Kazi Fariduddin

    A new technique, Iodine Neutron Capture Therapy (INCT) is proposed to treat hyperthyroidism in people. Present thyroid therapies, surgical removal and 131I treatment, result in hypothyroidism and, for 131I, involve protracted treatment times and excessive whole-body radiation doses. The new technique involves using a low energy neutron beam to convert a fraction of the natural iodine stored in the thyroid to radioactive 128I, which has a 24-minute half-life and decays by emitting 2.12-MeV beta particles. The beta particles are absorbed in and damage some thyroid tissue cells and consequently reduce the production and release of thyroid hormones to the blood stream. Treatment times and whole-body radiation doses are thus reduced substantially. This dissertation addresses the first of the several steps needed to obtain medical profession acceptance and regulatory approval to implement this therapy. As with other such programs, initial feasibility is established by performing experiments on suitable small mammals. Laboratory rats were used and their thyroids were exposed to the beta particles coming from small encapsulated amounts of 128I. Masses of 89.0 mg reagent-grade elemental iodine crystals have been activated in the ISU AGN-201 reactor to provide 0.033 mBq of 128I. This activity delivers 0.2 Gy to the thyroid gland of 300-g male rats having fresh thyroid tissue masses of ˜20 mg. Larger iodine masses are used to provide greater doses. The activated iodine is encapsulated to form a thin (0.16 cm 2/mg) patch that is then applied directly to the surgically exposed thyroid of an anesthetized rat. Direct neutron irradiation of a rat's thyroid was not possible due to its small size. Direct in-vivo exposure of the thyroid of the rat to the emitted radiation from 128I is allowed to continue for 2.5 hours (6 half-lives). Pre- and post-exposure blood samples are taken to quantify thyroid hormone levels. The serum T4 concentration is measured by radioimmunoassay at

  16. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  17. Superconducting High Resolution Fast-Neutron Spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Hau, Ionel Dragos [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    Superconducting high resolution fast-neutron calorimetric spectrometers based on 6LiF and TiB{sub 2} absorbers have been developed. These novel cryogenic spectrometers measure the temperature rise produced in exothermal (n, α) reactions with fast neutrons in 6Li and 10B-loaded materials with heat capacity C operating at temperatures T close to 0.1 K. Temperature variations on the order of 0.5 mK are measured with a Mo/Cu thin film multilayer operated in the transition region between its superconducting and its normal state. The advantage of calorimetry for high resolution spectroscopy is due to the small phonon excitation energies kBT on the order of μeV that serve as signal carriers, resulting in an energy resolution ΔE ~ (kBT2C)1/2, which can be well below 10 keV. An energy resolution of 5.5 keV has been obtained with a Mo/Cu superconducting sensor and a TiB2 absorber using thermal neutrons from a 252Cf neutron source. This resolution is sufficient to observe the effect of recoil nuclei broadening in neutron spectra, which has been related to the lifetime of the first excited state in 7Li. Fast-neutron spectra obtained with a 6Li-enriched LiF absorber show an energy resolution of 16 keV FWHM, and a response in agreement with the 6Li(n, α)3H reaction cross section and Monte Carlo simulations for energies up to several MeV. The energy resolution of order of a few keV makes this novel instrument applicable to fast-neutron transmission spectroscopy based on the unique elemental signature provided by the neutron absorption and scattering resonances. The optimization of the energy resolution based on analytical and numerical models of the detector response is discussed in the context of these applications.

  18. An improved prism energy analyzer for neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, J., E-mail: jennifer.schulz@helmholtz-berlin.de [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Ott, F. [Laboratoire Leon Brillouin, Bât 563 CEA Saclay, 91191 Gif sur Yvette Cedex (France); Krist, Th. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)

    2014-04-21

    The effects of two improvements of an existing neutron energy analyzer consisting of stacked silicon prism rows are presented. First we tested the effect of coating the back of the prism rows with an absorbing layer to suppress neutron scattering by total reflection and by refraction at small angles. Experiments at HZB showed that this works perfectly. Second the prism rows were bent to shift the transmitted wavelength band to larger wavelengths. At HZB we showed that bending increased the transmission of neutrons with a wavelength of 4.9 Å. Experiments with a white beam at the EROS reflectometer at LLB showed that bending of the energy analyzing device to a radius of 7.9 m allows to shift the transmitted wavelength band from 0 to 9 Å to 2 to 16 Å.

  19. Theory of neutron slowing down in nuclear reactors

    CERN Document Server

    Ferziger, Joel H; Dunworth, J V

    2013-01-01

    The Theory of Neutron Slowing Down in Nuclear Reactors focuses on one facet of nuclear reactor design: the slowing down (or moderation) of neutrons from the high energies with which they are born in fission to the energies at which they are ultimately absorbed. In conjunction with the study of neutron moderation, calculations of reactor criticality are presented. A mathematical description of the slowing-down process is given, with particular emphasis on the problems encountered in the design of thermal reactors. This volume is comprised of four chapters and begins by considering the problems

  20. Radiation shielding design for neutron diffractometers assisted by Monte Carlo methods

    Science.gov (United States)

    Osborn, John C.; Ersez, Tunay; Braoudakis, George

    2006-11-01

    Monte Carlo simulations may be used to model radiation shielding for neutron diffractometers. The use of the MCNP computer program to assess shielding for a diffractometer is discussed. A comparison is made of shielding requirements for radiation generated by several materials commonly used in neutron optical elements and beam stops, including lithium-6 based absorbers where the Monte Carlo method can model the effects of fast neutrons generated by this material.

  1. In-phantom dose mapping in neutron capture therapy by means of solid state detectors

    Science.gov (United States)

    Baccaro, S.; Cemmi, A.; Colombi, C.; Fiocca, M.; Gambarini, G.; Lietti, B.; Rosi, G.

    2004-01-01

    A method has been developed, based on thermoluminescent dosimeters and alanine, aimed at measuring the absorbed dose in tissue-equivalent phantoms exposed to an epithermal neutron beam suitable for neutron capture therapy (NCT), separating the contributions due to the various secondary radiations generated by neutrons. Exposures have been made at the TAPIRO nuclear reactor (ENEA, Italy), in the epithermal column properly designed and set up for experiments on boron NCT.

  2. Neutron Capture Nucleosynthesis

    CERN Document Server

    Kiss, Miklos

    2016-01-01

    Heavy elements (beyond iron) are formed in neutron capture nucleosynthesis processes. We have proposed a simple unified model to investigate the neutron capture nucleosynthesis in arbitrary neutron density environment. We have also investigated what neutron density is required to reproduce the measured abundance of nuclei assuming equilibrium processes. We found both of these that the medium neutron density has a particularly important role at neutron capture nucleosynthesis. About these results most of the nuclei can formed at medium neutron capture density environment e.g. in some kind of AGB stars. Besides these observations our model is capable to use educational purpose.

  3. Neutron detection by scintillation of noble-gas excimers

    Science.gov (United States)

    McComb, Jacob Collin

    Neutron detection is a technique essential to homeland security, nuclear reactor instrumentation, neutron diffraction science, oil-well logging, particle physics and radiation safety. The current shortage of helium-3, the neutron absorber used in most gas-filled proportional counters, has created a strong incentive to develop alternate methods of neutron detection. Excimer-based neutron detection (END) provides an alternative with many attractive properties. Like proportional counters, END relies on the conversion of a neutron into energetic charged particles, through an exothermic capture reaction with a neutron absorbing nucleus (10B, 6Li, 3He). As charged particles from these reactions lose energy in a surrounding gas, they cause electron excitation and ionization. Whereas most gas-filled detectors collect ionized charge to form a signal, END depends on the formation of diatomic noble-gas excimers (Ar*2, Kr*2,Xe* 2) . Upon decaying, excimers emit far-ultraviolet (FUV) photons, which may be collected by a photomultiplier tube or other photon detector. This phenomenon provides a means of neutron detection with a number of advantages over traditional methods. This thesis investigates excimer scintillation yield from the heavy noble gases following the boron-neutron capture reaction in 10B thin-film targets. Additionally, the thesis examines noble-gas excimer lifetimes with relationship to gas type and gas pressure. Experimental data were collected both at the National Institute of Standards and Technology (NIST) Center for Neutron Research, and on a newly developed neutron beamline at the Maryland University Training Reactor. The components of the experiment were calibrated at NIST and the University of Maryland, using FUV synchrotron radiation, neutron imaging, and foil activation techniques, among others. Computer modeling was employed to simulate charged-particle transport and excimer photon emission within the experimental apparatus. The observed excimer

  4. Innovative and Advanced Coupled Neutron Transport and Thermal Hydraulic Method (Tool) for the Design, Analysis and Optimization of VHTR/NGNP Prismatic Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Rahnema, Farzad; Garimeela, Srinivas; Ougouag, Abderrafi; Zhang, Dingkang

    2013-11-29

    This project will develop a 3D, advanced coarse mesh transport method (COMET-Hex) for steady- state and transient analyses in advanced very high-temperature reactors (VHTRs). The project will lead to a coupled neutronics and thermal hydraulic (T/H) core simulation tool with fuel depletion capability. The computational tool will be developed in hexagonal geometry, based solely on transport theory without (spatial) homogenization in complicated 3D geometries. In addition to the hexagonal geometry extension, collaborators will concurrently develop three additional capabilities to increase the code’s versatility as an advanced and robust core simulator for VHTRs. First, the project team will develop and implement a depletion method within the core simulator. Second, the team will develop an elementary (proof-of-concept) 1D time-dependent transport method for efficient transient analyses. The third capability will be a thermal hydraulic method coupled to the neutronics transport module for VHTRs. Current advancements in reactor core design are pushing VHTRs toward greater core and fuel heterogeneity to pursue higher burn-ups, efficiently transmute used fuel, maximize energy production, and improve plant economics and safety. As a result, an accurate and efficient neutron transport, with capabilities to treat heterogeneous burnable poison effects, is highly desirable for predicting VHTR neutronics performance. This research project’s primary objective is to advance the state of the art for reactor analysis.

  5. Advanced sources and optical components for the McStas neutron scattering instrument simulation package

    DEFF Research Database (Denmark)

    Farhi, E.; Monzat, C.; Arnerin, R.

    2014-01-01

    as in Guide_anyshape component for reflecting or absorbing complex set-up. The PSD_Detector component models a neutron absorbing gas volume, taking into account for instance the penetration depth and the associated parallax effect, the charge cloud generated at the absorption location. This gas volume can...

  6. Effect of Slag on Burnability Cement Raw Meal Containing Silica Crystals%矿渣对煅烧含高结晶态SiO2水泥生料的影响

    Institute of Scientific and Technical Information of China (English)

    艾红梅; 卢普光; 白军营; 卢洪正

    2012-01-01

    The burnability of raw materials and the quality of clinkers can be affected while too much quartz in raw material. Quartz will be brought in raw materials inevitably while the all components of waste concrete were used in cement production. Different proportions of slag were mixed in raw material in the experiment, the effect of slag on the clinker property and the burnability of raw material whose silicon materials were ISO standard sand was studied. The ethanol-glycol method was used to analyze the content of f-CaO, clinker minerals were identified by XRD, mineral morphology was observed by metalloscope, cement paste specimen were produced to test the compressive strength of hydrated clinker. The result showed that the burnability of raw materials with high quartz content was notably improved while adding the slag, slag also improved the formation of clinker mineral, while the amount of slag in raw materials was 3% ,hydrated clinker has the highest comprehensive strength; clinker produced more C-S-H gel and AFt in early hydration and C-S-H gel can be much denser in late hydration while moderate slag added in the raw materials.%利用含砂废弃混凝土原料煅烧水泥熟料,不可避免地会由细骨料砂引入结晶度较高的结晶态SiO2,不仅影响生料易烧性,而且影响硅酸盐矿物的组成和形貌,降低熟料质量.以ISO标准砂为硅质原料配制高结晶态SiO2含量的生料,按不同比例掺入矿渣,煅烧至不同温度;利用化学分析、XRD、岩相分析、SEM等方法,研究矿渣对水泥生料易烧性、熟料矿物组成和显微结构、熟料水化强度发展及水化产物形貌的影响.结果表明,适量矿渣的掺入可显著改善高结晶态SiO2含量水泥生料的易烧性,促进熟料矿物形成和发育;矿渣掺量为3%时,熟料水化后强度最高;适量矿渣可使熟料水化早期产生较多的C-S-H凝胶和钙矾石,而后期水化产物中C-S-H凝胶更密实,提高水泥强度.

  7. Waveform-dependent absorbing metasurfaces

    CERN Document Server

    Wakatsuchi, Hiroki; Rushton, Jeremiah J; Sievenpiper, Daniel F

    2014-01-01

    We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high power pulses but not for high power continuous waves (CWs), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e. CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications.

  8. Study of an electroacoustic absorber

    OpenAIRE

    Rodríguez de Antonio, Javier

    2008-01-01

    El problema de la atenuación del ruido de baja frecuencia todavía persiste pese a que ha sido ampliamente estudiado. Las técnicas para absorber ruido de alta frecuencia (superior a 500 Hz), como son los materiales porosos, resonadores de Helmholtz o espumas no ofrecen resultados aceptables a bajas frecuencias. Serían necesarios volúmenes impracticables de materiales porosos para intentar absorber frecuencias menores a 500 Hz, y lo mismo ocurre con los resonadores de Helmholtz. Esta ineficacia...

  9. Controllability of depth dose distribution for neutron capture therapy at the Heavy Water Neutron Irradiation Facility of Kyoto University Research Reactor.

    Science.gov (United States)

    Sakurai, Yoshinori; Kobayashi, Tooru

    2002-10-01

    The updating construction of the Heavy Water Neutron Irradiation Facility of the Kyoto University Research Reactor has been performed from November 1995 to March 1996 mainly for the improvement in neutron capture therapy. On the performance, the neutron irradiation modes with the variable energy spectra from almost pure thermal to epi-thermal neutrons became available by the control of the heavy-water thickness in the spectrum shifter and by the open-and-close of the cadmium and boral thermal neutron filters. The depth distributions of thermal, epi-thermal and fast neutron fluxes were measured by activation method using gold and indium, and the depth distributions of gamma-ray absorbed dose rate were measured using thermo-luminescent dosimeter of beryllium oxide for the several irradiation modes. From these measured data, the controllability of the depth dose distribution using the spectrum shifter and the thermal neutron filters was confirmed.

  10. Weapons Neutron Research Facility (WNR)

    Data.gov (United States)

    Federal Laboratory Consortium — The Weapons Neutron Research Facility (WNR) provides neutron and proton beams for basic, applied, and defense-related research. Neutron beams with energies ranging...

  11. Optimization of the epithermal neutron beam for Boron Neutron Capture Therapy at the Brookhaven Medical Research Reactor.

    Science.gov (United States)

    Hu, Jih-Perng; Reciniello, Richard N; Holden, Norman E

    2004-05-01

    The use of epithermal neutron beam in clinical trials of Boron Neutron Capture Therapy for patients with malignant brain tumors had been carried out for half a decade at the Brookhaven's Medical Reactor. The decision to permanently close this reactor in 2000 cut short the efforts to implement a new conceptual design to optimize this beam in preparation for use with possible new BNCT protocols. Details of the conceptual design to produce a highly intensified and focused neutron beam with less gamma and neutron contamination in tissues are presented here for their potential applicability to other reactor facilities. Neutron-photon coupled Monte Carlo calculations were used to predict the flux, current, heating, and absorbed dose produced by the proposed design. The results were benchmarked by the dose rate and flux measurements taken at the facility then in use.

  12. Neutron diffraction on CeMnAlD{sub x} (0{<=}x{<=}2.5)

    Energy Technology Data Exchange (ETDEWEB)

    Spatz, P.; Gross, K.; Schlapbach, L. [Fribourg Univ. (Switzerland); Fischer, P.; Fauth, F. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    CeMnAl was found to absorb considerable amounts of hydrogen. Part of the totally stored hydrogen is absorbed at low pressures (< 10 mbar). Additional hydrogen can be absorbed and desorbed reversible in a wide pressure range (10 mbar to 10 bar) at room temperature. In order to a better understanding of this new metal-hydride system, we performed neutron diffraction on deuterated CeMnAl samples with different D-concentrations. (author) 1 fig., 2 refs.

  13. Oil and fat absorbing polymers

    Science.gov (United States)

    Marsh, H. E., Jr. (Inventor)

    1977-01-01

    A method is described for forming a solid network polymer having a minimal amount of crosslinking for use in absorbing fats and oils. The polymer remains solid at a swelling ratio in oil or fat of at least ten and provides an oil absorption greater than 900 weight percent.

  14. Bioresorbable polymeric scaffolds for coronary revascularization: Lessons learnt from ABSORB III, ABSORB China, and ABSORB Japan.

    Science.gov (United States)

    Gogas, Bill D; King, Spencer B; Samady, Habib

    2015-01-01

    Bioresorbable polymers and biocorrodible metals are the latest developments in biodegradable materials used in interventional cardiology for the mechanical treatment of coronary atherosclerosis. Poly-L-lactic acid is the most frequently used bioresorbable polymer and initial evidence of feasibility, efficacy and clinical safety following deployment of polymer-based platforms was gained after completion of the first-in-man longitudinal ABSORB registries, Cohorts A and B and ABSORB Extend. In these studies, the biologic interaction of the first-generation Absorb Bioresorbable Vascular Scaffold (BVS) (Abbott Vascular, SC, Calif., US) with the underlying vascular tissue was evaluated in vivo with multiple imaging modalities such as intravascular ultrasound (IVUS), virtual histology-IVUS, IVUS-palpography, optical coherence tomography as well as ex vivo with coronary computed tomography. Efficacy measures following this in vivo multi-imaging assessment as well as clinical safety were comparable with current generation drug-eluting stents (DES) (Abbott Vascular, SC, Calif., US) in non-complex lesions over a 3-year follow-up. Furthermore, novel properties of functional and anatomic restoration of the vessel wall during the late phases of resorption and vascular healing were observed transforming the field of mechanical treatment of atherosclerosis from delivering only acute revascularization to additionally enable late repair and subsequent restoration of a more physiologic underlying vascular tissue. Despite the sufficient evidence and the subsequent Conformité Européenne mark approval of the first fully biodegradable scaffold (Absorb BVS) in 2012 for revascularizing non-complex lesions, the paucity of randomized comparisons of fully bioresorbable scaffolds (BRS) with metallic DES in a "real-world" clinical setting raised controversies among the interventional community for the merit of these technologies. Only recently, results from international large

  15. Superheated drop neutron spectrometer

    CERN Document Server

    Das, M; Roy, B; Roy, S C; Das, Mala

    2000-01-01

    Superheated drops are known to detect neutrons through the nucleation caused by the recoil nuclei produced by the interactions of neutrons with the atoms constituting the superheated liquid molecule. A novel method of finding the neutron energy from the temperature dependence response of SDD has been developed. From the equivalence between the dependence of threshold energy for nucleation on temperature of SDD and the dependence of dE/dx of the recoil ions with the energy of the neutron, a new method of finding the neutron energy spectrum of a polychromatic as well as monochromatic neutron source has been developed.

  16. Neutron streak camera

    Science.gov (United States)

    Wang, Ching L.

    1983-09-13

    Apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon.

  17. Using burnability index to control the burning temperature of rotary kiln%用生料易烧性指数控制回转窑煅烧温度

    Institute of Scientific and Technical Information of China (English)

    袁慧芳; 刘福东; 刘志刚; 杨克锐; 魏庆敏

    2001-01-01

    研究了带余热发电回转窑窑灰对熟料煅烧的影响,结果表明,窑灰的掺入对生料的易烧性和回转窑的煅烧有很大的影响,其中存在一个最佳掺入量。应该严格控制窑灰的加入量,才能保证窑的优质高产。生料的煅烧温度与其易烧性有直接的关系,在设备条件一定的情况下,可以用易烧性来控制窑的煅烧温度。%Influences of rotary kiln dust on clinker burning are investigated in this paper,which is a sub-project of Tangshan mechatronics project-cement synthetical intelligent automatic system.The results show that adding of rotary kiln dust affects both burnabiliy of raw mix and burning of rotary kiln strongly and a best adding amount exists.Adding amount of kiln dust must be controlled strictly to keep the kiln operating well.The burning temperature of raw mix has direct relations with its burnatiliy.Under the same device conditions,using burnability index can control burning temperature of the kiln.

  18. Neutron conversion and cascaded cooling in paramagnetic systems for a high-flux source of very cold neutrons

    Science.gov (United States)

    Zimmer, Oliver

    2016-03-01

    A new neutron-cooling mechanism is proposed with potential benefits for novel intense sources of very cold neutrons with wavelengths >2 nm, and for enhancing the production of ultracold neutrons. It employs inelastic magnetic scattering in weakly absorbing, cold paramagnetic systems. Kinetic energy is removed from the neutron stepwise in constant decrements determined by the Zeeman energy of paramagnetic atoms or ions in an external magnetic field, or by zero-field level splittings in magnetic molecules. The stationary neutron transport equation is analyzed for an infinite, homogeneous medium with Maxwellian neutron sources, using inelastic scattering cross sections derived in an appendix. Nonmagnetic inelastic scattering processes are neglected. The solution therefore still underestimates very cold neutron densities that should be achievable in a real medium. Molecular oxygen with its triplet ground state appears particularly promising, notably as a host in fully deuterated O2-clathrate hydrate. Other possibilities are dry O2-4He van der Waals clusters and O2 intercalated in fcc-C60. For conversion of cold to ultracold neutrons, where an incident neutron imparts only a single energy quantum to the medium, the paramagnetic scattering in the clathrate system is found to be stronger, by more than an order of magnitude, than the single-phonon emission in superfluid helium, when evaluated for an incident neutron spectrum with the optimum temperature for the respective medium. Moreover, the multistep paramagnetic cooling cascade leads to further strong enhancements of very cold neutron densities, e.g., by a factor 14 (57) for an initial neutron temperature of 30 K (100 K ), for the moderator held at about 1.3 K . Due to a favorable Bragg cutoff of the O2 clathrate, the cascade-cooling can take effect in a moderator with linear extensions smaller than a meter.

  19. ALD Produced B{sub 2}O{sub 3}, Al{sub 2}O{sub 3} and TiO{sub 2} Coatings on Gd{sub 2}O{sub 3} Burnable Poison Nanoparticles and Carbonaceous TRISO Coating Layers

    Energy Technology Data Exchange (ETDEWEB)

    Weimer, Alan

    2012-11-26

    This project will demonstrate the feasibility of using atomic layer deposition (ALD) to apply ultrathin neutron-absorbing, corrosion-resistant layers consisting of ceramics, metals, or combinations thereof, on particles for enhanced nuclear fuel pellets. Current pellet coating technology utilizes chemical vapor deposition (CVD) in a fluidized bed reactor to deposit thick, porous layers of C (or PyC) and SiC. These graphitic/carbide materials degrade over time owing to fission product bombardment, active oxidation, thermal management issues, and long-term irradiation effects. ALD can be used to deposit potential ceramic barrier materials of interest, including ZrO{sub 2}, Y{sub 2}O{sub 3}:ZrO{sub 2} (YSZ), Al{sub 2}O{sub 3}, and TiO{sub 2}, or neutron-absorbing materials, namely B (in BN or B{sub 2}O{sub 3}) and Gd (in Gd{sub 2}O{sub 3}). This project consists of a two-pronged approach to integrate ALD into the next-generation nuclear plant (NGNP) fuel pellet manufacturing process:

  20. Nuclear characteristics of epoxy resin as a space environment neutron shielding

    Energy Technology Data Exchange (ETDEWEB)

    Adeli, Ruhollah [Nuclear Science and Technology Research Institute, Yazd (Iran, Islamic Republic of). Central Iran Research Complex; Shirmardi, Seyed Pezhman [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). Radiation Application Research School; Mazinani, Saideh [Amirkabir Nanotechnology Research Institute, Tehran (Iran, Islamic Republic of); Ahmadi, Seyed Javad [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). Nuclear Fuel Cycle Research School

    2017-03-15

    In recent years many investigations have been done for choosing applicable light neutron shielding in space environmental applications. In this study, we have considered the neutron radiation-protective characteristics of neat epoxy resin, a thermoplastic polymer material and have compared it with various candidate materials in neutron radiation protection such as Al 6061 alloy and Polyethylene. The aim of this investigation is the effect of type of moderator for fast neutron, notwithstanding neutron absorbers fillers. The nuclear interactions and the effective dose at shields have been studied with the Monte Carlo N-Particle transport code (MCNP), using variance reductions to reduce the relative error. Among the candidates, polymer matrix showed a better performance in attenuating fast neutrons and caused a lower neutron and secondary photon effective dose.

  1. Dose spectra from energetic particles and neutrons

    Science.gov (United States)

    Schwadron, Nathan; Bancroft, Chris; Bloser, Peter; Legere, Jason; Ryan, James; Smith, Sonya; Spence, Harlan; Mazur, Joe; Zeitlin, Cary

    2013-10-01

    spectra from energetic particles and neutrons (DoSEN) are an early-stage space technology research project that combines two advanced complementary radiation detection concepts with fundamental advantages over traditional dosimetry. DoSEN measures not only the energy but also the charge distribution (including neutrons) of energetic particles that affect human (and robotic) health in a way not presently possible with current dosimeters. For heavy ions and protons, DoSEN provides a direct measurement of the lineal energy transfer (LET) spectra behind shielding material. For LET measurements, DoSEN contains stacks of thin-thick Si detectors similar in design to those used for the Cosmic Ray Telescope for the Effects of Radiation. With LET spectra, we can now directly break down the observed spectrum of radiation into its constituent heavy-ion components and through biologically based quality factors that provide not only doses and dose rates but also dose equivalents, associated rates, and even organ doses. DoSEN also measures neutrons from 10 to 100 MeV, which requires enough sensitive mass to fully absorb recoil particles that the neutrons produce. DoSEN develops the new concept of combining these independent measurements and using the coincidence of LET measurements and neutron detection to significantly reduce backgrounds in each measurement. The background suppression through the use of coincidence allows for significant reductions in size, mass, and power needed to provide measurements of dose, neutron dose, dose equivalents, LET spectra, and organ doses. Thus, we introduce the DoSEN concept: a promising low-mass instrument that detects the full spectrum of energetic particles, heavy ions, and neutrons to determine biological impact of radiation in space.

  2. Insight into magnetorheological shock absorbers

    CERN Document Server

    Gołdasz, Janusz

    2015-01-01

    This book deals with magnetorheological fluid theory, modeling and applications of automotive magnetorheological dampers. On the theoretical side a review of MR fluid compositions and key factors affecting the characteristics of these fluids is followed by a description of existing applications in the area of vibration isolation and flow-mode shock absorbers in particular. As a majority of existing magnetorheological devices operates in a so-called flow mode a critical review is carried out in that regard. Specifically, the authors highlight common configurations of flow-mode magnetorheological shock absorbers, or so-called MR dampers that have been considered by the automotive industry for controlled chassis applications. The authors focus on single-tube dampers utilizing a piston assembly with one coil or multiple coils and at least one annular flow channel in the piston.

  3. Optimum thickness of Mossbauer absorber

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    If recoilless fraction fa is available, the optimum absorber thickness dopt can be calculated by maximizing the signal to noise ratio or Q factor. In this work,an approach presented is to get experimental Qexp as a function of the thickness, and then fitting Qexp by its theoretical expression gives fa value. At last the dopt value is deduced from a maximum on the fitted curve. In such a way, thicknesses of six specimens with quadrupole or magnetic hyperfine splitting were optimized.

  4. Neutron anatomy

    Energy Technology Data Exchange (ETDEWEB)

    Bacon, G.E. [Univ. of Sheffield (United Kingdom)

    1994-12-31

    The familiar extremes of crystalline material are single-crystals and random powders. In between these two extremes are polycrystalline aggregates, not randomly arranged but possessing some preferred orientation and this is the form taken by constructional materials, be they steel girders or the bones of a human or animal skeleton. The details of the preferred orientation determine the ability of the material to withstand stress in any direction. In the case of bone the crucial factor is the orientation of the c-axes of the mineral content - the crystals of the hexagonal hydroxyapatite - and this can readily be determined by neutron diffraction. In particular it can be measured over the volume of a piece of bone, utilizing distances ranging from 1mm to 10mm. The major practical problem is to avoid the intense incoherent scattering from the hydrogen in the accompanying collagen; this can best be achieved by heat-treatment and it is demonstrated that this does not affect the underlying apatite. These studies of bone give leading anatomical information on the life and activities of humans and animals - including, for example, the life history of the human femur, the locomotion of sheep, the fracture of the legs of racehorses and the life-styles of Neolithic tribes. We conclude that the material is placed economically in the bone to withstand the expected stresses of life and the environment. The experimental results are presented in terms of the magnitude of the 0002 apatite reflection. It so happens that for a random powder the 0002, 1121 reflections, which are neighboring lines in the powder pattern, are approximately equal in intensity. The latter reflection, being of manifold multiplicity, is scarcely affected by preferred orientation so that the numerical value of the 0002/1121 ratio serves quite accurately as a quantitative measure of the degree of orientation of the c-axes in any chosen direction for a sample of bone.

  5. Neutron-Activatable Needles for Radionuclide Therapy of Solid Tumors.

    Science.gov (United States)

    Kim, Junghyun; Narayan, Roger J; Lu, Xiuling; Jay, Michael

    2017-08-14

    Various approaches have been undertaken to enhance the delivery of therapeutic agents, including tissue-killing radionuclides, into solid tumors. Here we describe the preparation of conical needles composed of Ti and Mo coated by pulsed laser deposition or chemical vapor deposition with elements (Ho and Re) that can readily yield radioactive isotopes following irradiation in a neutron flux. The radioactive needles, whose design were based on solid microneedle arrays used in transdermal drug delivery, can be produced with minimal handling of radioactivity and subsequently inserted into tumors as a means of internal radiation therapy. Ho and Re, were specifically chosen because of their large neutron capture cross-sections as well as the desirable radiotherapeutic properties of the resultant radionuclides. Neutron-absorbing shields were also developed to prevent the production of unwanted radionuclides after neutron irradiation of the needle base materials. Neutron activation calculations showed that therapeutically significant amounts of radionuclides can be produced for treating solid tumors. Stability studies demonstrated that Re did not leach off the Mo needles. These coated neutron-activatable needles offer a new approach to internal radiation therapy of tumors that allows precise tailoring of the absorbed radiation dose delivered to the tumor by controlling the coating thickness and the irradiation time. This article is protected by copyright. All rights reserved. © 2017 Wiley Periodicals, Inc.

  6. A Capture-gated Fast Neutron Detection Method

    CERN Document Server

    Liu, Yi; Tai, Yang; Zhang, Zhi

    2016-01-01

    To address the problem of the shortage of neutron detectors used in radiation portal monitors (RPMs), caused by the 3He supply crisis, research on a cadmium-based capture-gated fast neutron detector is presented in this paper. The detector is composed of many 1 cm * 1 cm * 20 cm plastic scintillator cuboids covered by 0.1 mm thick film of cadmium. The detector uses cadmium to absorb thermal neutrons and produce capture gamma-rays to indicate the detection of neutrons, and uses plastic scintillator to moderate neutrons and register gamma-rays. This design removes the volume competing relationship in traditional 3He counter-based fast neutron detectors, which hinders enhancement of the neutron detection efficiency. Detection efficiency of 21.66 +- 1.22% has been achieved with a 40.4 cm * 40.4 cm * 20 cm overall detector volume. This detector can measure both neutrons and gamma-rays simultaneously. A small detector (20.2 cm * 20.2 cm * 20 cm) demonstrated a 3.3 % false alarm rate for a 252Cf source with a neutro...

  7. Imaging with Scattered Neutrons

    OpenAIRE

    Ballhausen, H.; Abele, H.; Gaehler, R.; Trapp, M.; Van Overberghe, A.

    2006-01-01

    We describe a novel experimental technique for neutron imaging with scattered neutrons. These scattered neutrons are of interest for condensed matter physics, because they permit to reveal the local distribution of incoherent and coherent scattering within a sample. In contrast to standard attenuation based imaging, scattered neutron imaging distinguishes between the scattering cross section and the total attenuation cross section including absorption. First successful low-noise millimeter-re...

  8. Intense fusion neutron sources

    Science.gov (United States)

    Kuteev, B. V.; Goncharov, P. R.; Sergeev, V. Yu.; Khripunov, V. I.

    2010-04-01

    The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 1015-1021 neutrons/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion neutrons in systems with magnetic and inertial plasma confinement are achieved. The proposed plasma methods for neutron production are compared with other methods based on fusion reactions in nonplasma media, fission reactions, spallation, and muon catalysis. At present, intense neutron fluxes are mainly used in nanotechnology, biotechnology, material science, and military and fundamental research. In the near future (10-20 years), it will be possible to apply high-power neutron sources in fusion-fission hybrid systems for producing hydrogen, electric power, and technological heat, as well as for manufacturing synthetic nuclear fuel and closing the nuclear fuel cycle. Neutron sources with intensities approaching 1020 neutrons/s may radically change the structure of power industry and considerably influence the fundamental and applied science and innovation technologies. Along with utilizing the energy produced in fusion reactions, the achievement of such high neutron intensities may stimulate wide application of subcritical fast nuclear reactors controlled by neutron sources. Superpower neutron sources will allow one to solve many problems of neutron diagnostics, monitor nano-and biological objects, and carry out radiation testing and modification of volumetric properties of materials at the industrial level. Such sources will considerably (up to 100 times) improve the accuracy of neutron physics experiments and will provide a better understanding of the structure of matter, including that of the neutron itself.

  9. International Neutron Radiography Newsletter

    DEFF Research Database (Denmark)

    Domanus, Joseph Czeslaw

    1986-01-01

    At the First World Conference on Neutron Radiography i t was decided to continue the "Neutron Radiography Newsletter", published previously by J.P. Barton, as the "International Neutron Radiography Newsletter" (INRNL), with J.C. Doraanus as editor. The British Journal of Non-Destructive Testing...

  10. Prototype Neutron Energy Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Mitchell, Sanjoy Mukhopadhyay, Richard Maurer, Ronald Wolff

    2010-06-16

    The project goals are: (1) Use three to five pressurized helium tubes with varying polyethylene moderators to build a neutron energy spectrometer that is most sensitive to the incident neutron energy of interest. Neutron energies that are of particular interest are those from the fission neutrons (typically around 1-2 MeV); (2) Neutron Source Identification - Use the neutron energy 'selectivity' property as a tool to discriminate against other competing processes by which neutrons are generated (viz. Cosmic ray induced neutron production [ship effect], [a, n] reactions); (3) Determine the efficiency as a function of neutron energy (response function) of each of the detectors, and thereby obtain the composite neutron energy spectrum from the detector count rates; and (4) Far-field data characterization and effectively discerning shielded fission source. Summary of the presentation is: (1) A light weight simple form factor compact neutron energy spectrometer ready to be used in maritime missions has been built; (2) Under laboratory conditions, individual Single Neutron Source Identification is possible within 30 minutes. (3) Sources belonging to the same type of origin viz., (a, n), fission, cosmic cluster in the same place in the 2-D plot shown; and (4) Isotopes belonging to the same source origin like Cm-Be, Am-Be (a, n) or Pu-239, U-235 (fission) do have some overlap in the 2-D plot.

  11. The Monte Carlo simulation of neutron transmitted and scattered by disk choppers of various compositions

    Energy Technology Data Exchange (ETDEWEB)

    Baek, I.; Carpenter, J.M. [Intense Pulsed Neutron Source, Argonne National Laboratory, Argonne, IL (United States); Iverson, E.B. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2001-03-01

    We consider the transmission of neutrons through disk-type neutron choppers, considering both the uncollided neutron fraction ({phi}{sub u}) and scattered neutron fraction ({phi}{sub s}). We computed {phi}{sub u}, {phi}{sub s}, and the ratio {phi}{sub u}/{phi}{sub s} through plates of five different absorber materials of various thicknesses to give information for selecting optimum materials and thicknesses. We also studied variance-reducing techniques for Monte Carlo calculation of chopper using MCNP4b, selecting those most effective for these calculations. (author)

  12. Plasmonic titanium nitride nanostructures for perfect absorbers

    DEFF Research Database (Denmark)

    Guler, Urcan; Li, Wen-Wei; Kinsey, Nathaniel

    2013-01-01

    We propose a metamaterial based perfect absorber in the visible region, and investigate the performance of titanium nitride as an alternative plasmonic material. Numerical and experimental results reveal that titanium nitride performs better than gold as a plasmonic absorbing material...

  13. Neutron spectrum and dose-equivalent in shuttle flights during solar maximum

    Energy Technology Data Exchange (ETDEWEB)

    Keith, J.E.; Badhwar, G.D.; Lindstrom, D.J. (National Aeronautics and Space Administration, Houston, TX (United States). Lyndon B. Johnson Space Center)

    1992-01-01

    This paper presents unambiguous measurements of the spectrum of neutrons found in spacecraft during spaceflight. The neutron spectrum was measured from thermal energies to about 10 MeV using a completely passive system of metal foils as neutron detectors. These foils were exposed to the neutron flux bare, covered by thermal neutron absorbers (Gd) and inside moderators (Bonner spheres). This set of detectors was flown on three U.S. Space Shuttle flights, STS-28, STS-36 and STS-31, during the solar maximum. We show that the measurements of the radioactivity of these foils lead to a differential neutron energy spectrum in all three flights that can be represented by a power law, J(E){approx equal}E{sup -0.765} neutrons cm{sup -2} day {sup -1} MeV{sup -1}. We also show that the measurements are even better represented by a linear combination of the terrestrial neutron albedo and a spectrum of neutrons locally produced in a aluminium by protons, computed by a previous author. We use both approximations to the neutron spectrum to produce a worst case and most probable case for the neutron spectra and the resulting dose-equivalents, computed using ICRP-51 neutron fluence-dose conversion tables. We compare these to the skin dose-equivalents due to charged particles during the same flights. (author).

  14. Remarks on Wheeler-Feynman absorber theory

    OpenAIRE

    Gründler, Gerold

    2014-01-01

    The derivation of absorber theory is outlined in very detail. Absorber theory is based on classical action-at-a-distance electrodynamics, but it deviates from that theory at a crucial point. It is shown that (a) absorber theory cannot achieve any of it's essential results without this deviation, and that (b) this deviation restricts the application range of absorber theory to stationary radiation processes. Furthermore an error which crept into Wheeler's and Feynman's interpretation of their ...

  15. Synchrotron radiation absorber for high density loads

    Science.gov (United States)

    Anashin, V. V.; Kuzminych, V. S.; Trakhtenberg, E. M.; Zholents, A. A.

    1991-10-01

    A design of a special synchrotron radiation absorber for the storage ring VEPP-4M is presented. The density of the synchrotron radiation power on the absorber surface is up to 500 W/mm 2. The absorber is made from a beryllium plate, brazed inside to the copper vacuum chamber, which is intensively water-cooled from outside.

  16. Neutron Detection with Mercuric Iodide

    CERN Document Server

    Bell, Z A

    2003-01-01

    Mercuric iodide is a high-density, high-Z semiconducting material useful for gamma ray detection. This makes it convertible to a thermal neutron detector by covering it with a boron rich material and detecting the 478 keV gamma rays resulting from the sup 1 sup 0 B(n, alpha) sup 7 Li* reaction. However, the 374 barn thermal capture cross section of sup n sup a sup t Hg, makes the detector itself an attractive absorber, and this has been exploited previously. Since previous work indicates that there are no low-energy gamma rays emitted in coincidence with the 368 keV capture gamma from the dominant sup 1 sup 9 sup 9 Hg(n, gamma) sup 2 sup 0 sup 0 Hg reaction, only the 368 keV capture gamma is seen with any efficiency a relatively thin (few mm) detector. In this paper we report preliminary measurements of neutrons via capture reactions in a bare mercuric iodide crystal and a crystal covered in sup 1 sup 0 B-loaded epoxy. The covered detector is an improvement over the bare detector because the presence of both ...

  17. Neutron scattering. Experiment manuals

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: The thermal triple axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, neutron polarization analysis with tht time-of-flight spectrometer DNS, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering with the KWS-1 and KWS-2 diffractometers, the very-small-angle neutron scattering diffractrometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  18. Grazing Incidence Neutron Optics

    Science.gov (United States)

    Gubarev, Mikhail V. (Inventor); Ramsey, Brian D. (Inventor); Engelhaupt, Darell E. (Inventor)

    2013-01-01

    Neutron optics based on the two-reflection geometries are capable of controlling beams of long wavelength neutrons with low angular divergence. The preferred mirror fabrication technique is a replication process with electroform nickel replication process being preferable. In the preliminary demonstration test an electroform nickel optics gave the neutron current density gain at the focal spot of the mirror at least 8 for neutron wavelengths in the range from 6 to 20.ANG.. The replication techniques can be also be used to fabricate neutron beam controlling guides.

  19. Neutron scatter camera

    Science.gov (United States)

    Mascarenhas, Nicholas; Marleau, Peter; Brennan, James S.; Krenz, Kevin D.

    2010-06-22

    An instrument that will directly image the fast fission neutrons from a special nuclear material source has been described. This instrument can improve the signal to background compared to non imaging neutron detection techniques by a factor given by ratio of the angular resolution window to 4.pi.. In addition to being a neutron imager, this instrument will also be an excellent neutron spectrometer, and will be able to differentiate between different types of neutron sources (e.g. fission, alpha-n, cosmic ray, and D-D or D-T fusion). Moreover, the instrument is able to pinpoint the source location.

  20. Piezooptic effect of absorbing environment

    Directory of Open Access Journals (Sweden)

    Ю. А. Рудяк

    2013-07-01

    Full Text Available Application of piezooptic effect of absorbing environment for the definition of the parameter of stress deformation state was examined. The analysis of dielectric permeability tensor of imaginary parts was done. It is shown that changes in the real part dielectric permeability tensor mainly the indicator of fracture was fixed by means of mechanics interference methods and the changes in the imaginary part (α – real rate of absorption can be measured by means of analysis of light absorption and thus stress deformation state can be determined

  1. Advances in neutron tomography

    Indian Academy of Sciences (India)

    W Treimer

    2008-11-01

    In the last decade neutron radiography (NR) and tomography (NCT) have experienced a number of improvements, due to the well-known properties of neutrons interacting with matter, i.e. the low attenuation by many materials, the strong attenuation by hydrogenous constituent in samples, the wavelength-dependent attenuation in the neighbourhood of Bragg edges and due to better 2D neutron detectors. So NR and NCT were improved by sophisticated techniques that are based on the attenuation of neutrons or on phase changes of the associated neutron waves if they pass through structured materials. Up to now the interaction of the neutron spin with magnetic fields in samples has not been applied to imaging techniques despite the fact that it was proposed many years ago. About ten years ago neutron depolarization as imaging signal for neutron radiography or tomography was demonstrated and in principle it works. Now one can present much improved test experiments using polarized neutrons for radiographic imaging. For this purpose the CONRAD instrument of the HMI was equipped with polarizing and analysing benders very similar to conventional scattering experiments using polarized neutrons. Magnetic fields in different coils and in samples (superconductors) at low temperatures could be visualized. In this lecture a summary about standard signals (attenuation) and the more `sophisticated' imaging signals as refraction, small angle scattering and polarized neutrons will be given.

  2. Early clinical experience utilizing scintillator with optical fiber (SOF) detector in clinical boron neutron capture therapy: its issues and solutions

    OpenAIRE

    Ishikawa, Masayori; Yamamoto, Tetsuya; Matsumura, Akira; Hiratsuka, Junichi; Miyatake, Shin-Ichi; Kato, Itsuro; Sakurai, Yoshinori; Kumada, Hiroaki; Shrestha, Shubhechha J.; ONO, KOJI

    2016-01-01

    Background Real-time measurement of thermal neutrons in the tumor region is essential for proper evaluation of the absorbed dose in boron neutron capture therapy (BNCT) treatment. The gold wire activation method has been routinely used to measure the neutron flux distribution in BNCT irradiation, but a real-time measurement using gold wire is not possible. To overcome this issue, the scintillator with optical fiber (SOF) detector has been developed. The purpose of this study is to demonstrate...

  3. Carbon dioxide absorbents for rebreather diving.

    Science.gov (United States)

    Pennefather, John

    2016-09-01

    Firstly I would like to thank SPUMS members for making me a Life Member of SPUMS; I was surprised and greatly honoured by the award. I also want to confirm and expand on the findings on carbon dioxide absorbents reported by David Harvey et al. For about 35 years, I was the main player in deciding which absorbent went into Australian Navy and Army diving sets. On several occasions, suppliers of absorbents to the anaesthesia market tried to supply the Australian military market. On no occasion did they provide absorbent that came close to the minimum absorbent capacity required, generally being 30-40% less efficient than diving-grade absorbents. Because I regard lives as being more important than any likely dollar saving, the best absorbent was always selected unless two suppliers provided samples with the same absorbent capacity. On almost every occasion, there was a clear winner and cost was never considered. I suggest the same argument for the best absorbent should be used by members and their friends who dive using rebreather sets. I make this point because of my findings on a set that was brought to me after the death of its owner. The absorbent was not the type or grain size recommended by the manufacturer of the set and did not resemble any of the diving grade absorbents I knew of. I suspected by its appearance that it was anaesthetic grade absorbent. When I tested the set, the absorbent system failed very quickly so it is likely that carbon dioxide toxicity contributed to his death. The death was not the subject of an inquest and I have no knowledge of how the man obtained the absorbent. Possibly there was someone from an operating theatre staff who unintentionally caused their friend's death by supplying him with 'borrowed absorbent'. I make this point as I would like to discourage members from making a similar error.

  4. Radiation-Induced Color Centers in LiF for Dosimetry at High Absorbed Dose Rates

    DEFF Research Database (Denmark)

    McLaughlin, W. L.; Miller, Arne; Ellis, S. C.

    1980-01-01

    Color centers formed by irradiation of optically clear crystals of pure LiF may be analyzed spectrophotometrically for dosimetry in the absorbed dose range from 102 to 107 Gy. Routine monitoring of intense electron beams is an important application. Both 6LiF and 7LiF forms are commercially avail...... available, and when used with filters as albedo dosimeters in pairs, they provide discrimination of neutron and gamma-ray doses....

  5. A polarization-independent broadband terahertz absorber

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Cheng; Zang, XiaoFei, E-mail: xfzang@usst.edu.cn, E-mail: ymzhu@usst.edu.cn; Wang, YiQiao; Chen, Lin; Cai, Bin; Zhu, YiMing, E-mail: xfzang@usst.edu.cn, E-mail: ymzhu@usst.edu.cn [Shanghai Key Laboratory of Modern Optical System and Engineering Research Center of Optical Instrument and System, Ministry of Education, University of Shanghai for Science and Technology, Shanghai 200093 (China)

    2014-07-21

    A highly efficient broadband terahertz absorber is designed, fabricated, and experimentally as well as theoretically evaluated. The absorber comprises a heavily doped silicon substrate and a well-designed two-dimensional grating. Due to the destructive interference of waves and diffraction, the absorber can achieve over 95% absorption in a broad frequency range from 1 to 2 THz and for angles of incidence from 0° to 60°. Such a terahertz absorber is also polarization-independent due to its symmetrical structure. This omnidirectional and broadband absorber have potential applications in anti-reflection coatings, imaging systems, and so on.

  6. Remarks on Wheeler-Feynman absorber theory

    CERN Document Server

    Gründler, Gerold

    2015-01-01

    The derivation of absorber theory is outlined in very detail. Absorber theory is based on classical action-at-a-distance electrodynamics, but it deviates from that theory at a crucial point. It is shown that (a) absorber theory cannot achieve any of it's essential results without this deviation, and that (b) this deviation restricts the application range of absorber theory to stationary radiation processes. Furthermore an error which crept into Wheeler's and Feynman's interpretation of their equation (19) is pointed out. These shortcomings can probably be eliminated by a quantum-theoretical formulation of absorber theory.

  7. Multi-channel coherent perfect absorbers

    KAUST Repository

    Bai, Ping

    2016-05-18

    The absorption efficiency of a coherent perfect absorber usually depends on the phase coherence of the incident waves on the surfaces. Here, we present a scheme to create a multi-channel coherent perfect absorber in which the constraint of phase coherence is loosened. The scheme has a multi-layer structure such that incident waves in different channels with different angular momenta can be simultaneously and perfectly absorbed. This absorber is robust in achieving high absorption efficiency even if the incident waves become "incoherent" and possess "random" wave fronts. Our work demonstrates a unique approach to designing highly efficient metamaterial absorbers. © CopyrightEPLA, 2016.

  8. Optimization of the Epithermal Neutron Beam for Boron Neutron Capture Therapy at the Brookhaven Medical Research Reactor

    Science.gov (United States)

    Hu, Jih-Perng; Rorer, David C.; Reciniello, Richard N.; Holden, Norman E.

    2003-06-01

    Clinical trials of Boron Neutron Capture Therapy for patients with malignant brain tumor had been carried out for half a decade, using an epithermal neutron beam at the Brookhaven Medical Reactor. The decision to permanently close this reactor in 2000 cut short the efforts to implement a new conceptual design to optimize this beam in preparation for use with possible new protocols. Details of the conceptual design to produce a higher intensity, more forward-directed neutron beam with less contamination from gamma rays, fast and thermal neutrons are presented here for their potential applicability to other reactor facilities. Monte Carlo calculations were used to predict the flux and absorbed dose produced by the proposed design. The results were benchmarked by the dose rate and flux measurements taken at the facility then in use.

  9. Importance of the elemental composition in brachytherapy with neutrons; Importancia de la composicion elemental en braquiterapia con neutrones

    Energy Technology Data Exchange (ETDEWEB)

    Paredes G, L.; Balcazar G, M. [ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico); Azorin N, J. [UAM-I, 09340 Mexico D.F. (Mexico); Francois L, J.L. [ICN-UNAM, 04510 Mexico D.F. (Mexico)

    2004-07-01

    An analysis is presented of as the small differences that exist in the elementary composition of the wicked tumors, healthy fabrics and some material substitutes of fabric employees in dosimetry, they generate variations in the value of the kerma coefficient and consequently in the absorbed dose of neutrons in the interval 11 eV to 29 MeV. These differences make that the coefficient of kerma of neutrons average for the considered wicked tumors, be between 6% and 7% smaller that the coefficient of kerma of neutrons average for soft fabric, in the interval of interest in therapy with quick neutrons. These results have a special importance during the process of planning of brachytherapy treatments with sources of {sup 252} Cf, to optimize and to individualize the treatments to the patients. (Author)

  10. Neutron dose estimation in a zero power nuclear reactor

    Science.gov (United States)

    Triviño, S.; Vedelago, J.; Cantargi, F.; Keil, W.; Figueroa, R.; Mattea, F.; Chautemps, A.; Santibañez, M.; Valente, M.

    2016-10-01

    This work presents the characterization and contribution of neutron and gamma components to the absorbed dose in a zero power nuclear reactor. A dosimetric method based on Fricke gel was implemented to evaluate the separation between dose components in the mixed field. The validation of this proposed method was performed by means of direct measurements of neutron flux in different positions using Au and Mg-Ni activation foils. Monte Carlo simulations were conversely performed using the MCNP main code with a dedicated subroutine to incorporate the exact complete geometry of the nuclear reactor facility. Once nuclear fuel elements were defined, the simulations computed the different contributions to the absorbed dose in specific positions inside the core. Thermal/epithermal contributions of absorbed dose were assessed by means of Fricke gel dosimetry using different isotopic compositions aimed at modifying the sensitivity of the dosimeter for specific dose components. Clear distinctions between gamma and neutron capture dose were obtained. Both Monte Carlo simulations and experimental results provided reliable estimations about neutron flux rate as well as dose rate during the reactor operation. Simulations and experimental results are in good agreement in every positions measured and simulated in the core.

  11. Microdosimetric investigations at the Fast Neutron Therapy Facility at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Langen, K.M.

    1997-12-31

    Microdosimetry was used to investigate three issues at the neutron therapy facility (NTF) at Fermilab. Firstly, the conversion factor from absorbed dose in A-150 tissue equivalent plastic to absorbed dose in ICRU tissue was determined. For this, the effective neutron kerma factor ratios, i.e. oxygen tissue equivalent plastic and carbon to A-150 tissue equivalent plastic, were measured in the neutron beam. An A-150 tissue equivalent plastic to ICRU tissue absorbed dose conversion factor of 0.92 {+-} 0.04 determined. Secondly, variations in the radiobiological effectiveness (RBE) in the beam were mapped by determining variations in two related quantities, e{sup *} and R, with field size and depth in tissue. Maximal variation in e{sup *} and R of 9% and 15% respectively were determined. Lastly, the feasibility of utilizing the boron neutron capture reaction on boron-10 to selectively enhance the tumor dose in the NTF beam was investigated. In the unmodified beam, a negligible enhancement for a 50 ppm boron loading was measured. To boost the boron dose enhancement to 3% it was necessary to change the primary proton energy from 66 MeV and to filter the beam by 90 mm of tungsten.

  12. Real-Time Active Cosmic Neutron Background Reduction Methods

    Energy Technology Data Exchange (ETDEWEB)

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald; Mitchell, Stephen; Guss, Paul

    2013-09-01

    Neutron counting using large arrays of pressurized 3He proportional counters from an aerial system or in a maritime environment suffers from the background counts from the primary cosmic neutrons and secondary neutrons caused by cosmic ray-induced mechanisms like spallation and charge-exchange reaction. This paper reports the work performed at the Remote Sensing Laboratory–Andrews (RSL-A) and results obtained when using two different methods to reduce the cosmic neutron background in real time. Both methods used shielding materials with a high concentration (up to 30% by weight) of neutron-absorbing materials, such as natural boron, to remove the low-energy neutron flux from the cosmic background as the first step of the background reduction process. Our first method was to design, prototype, and test an up-looking plastic scintillator (BC-400, manufactured by Saint Gobain Corporation) to tag the cosmic neutrons and then create a logic pulse of a fixed time duration (~120 μs) to block the data taken by the neutron counter (pressurized 3He tubes running in a proportional counter mode). The second method examined the time correlation between the arrival of two successive neutron signals to the counting array and calculated the excess of variance (Feynman variance Y2F)1 in the neutron count distribution from Poisson distribution. The dilution of this variance from cosmic background values ideally would signal the presence of man-made neutrons.2 The first method has been technically successful in tagging the neutrons in the cosmic-ray flux and preventing them from being counted in the 3He tube array by electronic veto—field measurement work shows the efficiency of the electronic veto counter to be about 87%. The second method has successfully derived an empirical relationship between the percentile non-cosmic component in a neutron flux and the Y2F of the measured neutron count distribution. By using shielding materials alone, approximately 55% of the neutron flux

  13. Development and calculation of an energy dependent normal brain tissue neutron RBE for evaluating neutron fields for BNCT.

    Science.gov (United States)

    Woollard, J E; Blue, T E; Gupta, N; Gahbauer, R A

    2001-06-01

    In Boron Neutron Capture Therapy (BNCT) of malignant brain tumors, the energy dependence of a clinically relevant Relative Biological Effectiveness (RBE) for epithermal neutrons, RBE(En), is important in neutron field design. In the first half of this paper, we present the development of an expression for the energy dependent normal-tissue RBE, RBE(En). We then calculate a reasonable estimate for RBE(En) for adult brain tissue. In the second half of the paper, two separate RBE expressions are developed, one for the RBE of the neutrons that interact in tissue via the 14N(n,p)14C reaction, denoted RBE(N), and one for the RBE of the neutrons which interact in tissue via the 1H(n,n')1H reaction, denoted RBE(H). The absorbed-dose-averaged values of these expressions are calculated for the neutron flux spectrum in phantom for the Brookhaven Medical Research Reactor (BMRR) epithermal neutron beam. The calculated values, [RBE(norm)N] = 3.4 and [RBE(norm)H] = 3.2, are within 6% of being equal, and support the use of equal values for RBEN and RBE(H) by researchers at Brookhaven National Laboratory (BNL). Finally, values of [RBE(norm)N] and [RBE(norm)H], along with the absorbed-dose-averaged RBE for brain, [RBE(norm)b], were calculated as a function of depth along the centerline of an ellipsoidal head phantom using flux spectra calculated for our Accelerator-Based Neutron Source (ABNS). These values remained essentially constant with depth, supporting the use of constant values for RBE, as is done at BNL.

  14. Compact, energy EFFICIENT neutron source: enabling technology for various applications

    Energy Technology Data Exchange (ETDEWEB)

    Hershcovitch, A.; Roser, T.

    2009-12-01

    A novel neutron source comprising of a deuterium beam (energy of about 100 KeV) injected into a tube filled with tritium gas and/or tritium plasma that generates D-T fusion reactions, whose products are 14.06 MeV neutrons and 3.52 MeV alpha particles, is described. At the opposite end of the tube, the energy of deuterium ions that did not interact is recovered. Beryllium walls of proper thickness can be utilized to absorb 14 MeV neutrons and release 2-3 low energy neutrons. Each ion source and tube forms a module. Larger systems can be formed from multiple units. Unlike currently proposed methods, where accelerator-based neutron sources are very expensive, large, and require large amounts of power for operation, this neutron source is compact, inexpensive, easy to test and to scale up. Among possible applications for this neutron source concept are sub-critical nuclear breeder reactors and transmutation of radioactive waste.

  15. Status of spallation neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Oyama, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-03-01

    Existing and planned facilities using proton accelerator driven spallation neutron source are reviewed. These include new project of neutron science proposed from Japan Atomic Energy Research Institute. The present status of facility requirement and accelerator technology leads us to new era of neutron science such as neutron scattering research and nuclear transmutation study using very intense neutron source. (author)

  16. 铀氢锆堆中子源辐照含硼C6胶质瘤细胞的生物学效应研究%Biological effects of boron-absorbed C6 glioma cells irradiated by UHZr reactor neutron source

    Institute of Scientific and Technical Information of China (English)

    江新标; 赵英; 曹锐锋; 肖艳; 陈伟; 屠荆; 章翔

    2005-01-01

    利用蒙卡程序MCNP/4B(Monte Carlo N-particle transportcode/4B)设计了C6细胞辐照实验的铀氢锆堆中子源.建立了细胞培养、孵育、L-BPA(L-boron phenylalanine)给药、细胞内宏观硼浓度测定及辐照实验方法,观察了BNCT(Boron neutron capture therapy)辐照实验对体外C6胶质瘤细胞的放射生物学效应,研究了C6细胞BNCT辐照效应与照射剂量之间的关系.试验结果表明,在同等吸收剂量下,BNCT对C6细胞的杀伤作用远远大于γ射线.

  17. Preliminary study of neutron absorption by concrete with boron carbide addition

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, Yusof, E-mail: yusofabd@nuclearmalaysia.gov.my; Yusof, Mohd Reusmaazran; Zali, Nurazila Mat; Ahmad, Megat Harun Al Rashid Megat; Yazid, Hafizal [Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia); Ariffin, Fatin Nabilah Tajul; Ahmad, Sahrim [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor (Malaysia); Hamid, Roszilah [Department of Civil and Structural Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor (Malaysia); Mohamed, Abdul Aziz [College of Engineering, Universiti Tenaga National, Jalan Ikram-Uniten, 43000 Kajang, Selangor (Malaysia)

    2014-02-12

    Concrete has become a conventional material in construction of nuclear reactor due to its properties like safety and low cost. Boron carbide was added as additives in the concrete construction as it has a good neutron absorption property. The sample preparation for concrete was produced with different weight percent of boron carbide powder content. The neutron absorption rate of these samples was determined by using a fast neutron source of Americium-241/Be (Am-Be 241) and detection with a portable backscattering neutron detector. Concrete with 20 wt % of boron carbide shows the lowest count of neutron transmitted and this indicates the most neutrons have been absorbed by the concrete. Higher boron carbide content may affect the concrete strength and other properties.

  18. Pulse-shape analysis for gamma background rejection in thermal neutron radiation using CVD diamond detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kavrigin, P., E-mail: pavel.kavrigin@cividec.at [Vienna University of Technology (Austria); Finocchiaro, P., E-mail: finocchiaro@lns.infn.it [INFN Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Griesmayer, E., E-mail: erich.griesmayer@cividec.at [Vienna University of Technology (Austria); Jericha, E., E-mail: jericha@ati.ac.at [Vienna University of Technology (Austria); Pappalardo, A., E-mail: apappalardo@lns.infn.it [INFN Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Weiss, C., E-mail: Christina.Weiss@cern.ch [Vienna University of Technology (Austria); European Organisation for Nuclear Research (CERN), Geneva (Switzerland)

    2015-09-21

    A novel technique for the rejection of gamma background from charged-particle spectra was demonstrated using a CVD diamond detector with a {sup 6}Li neutron converter installed at a thermal neutron beamline of the TRIGA research reactor at the Atominstitut (Vienna University of Technology). Spectra of the alpha particles and tritons of {sup 6}Li(n,T){sup 4}He thermal neutron capture reaction were separated from the gamma background by a new algorithm based on pulse-shape analysis. The thermal neutron capture in {sup 6}Li is already used for neutron flux monitoring, but the ability to remove gamma background allows using a CVD diamond detector for thermal neutron counting. The pulse-shape analysis can equally be applied to all cases where the charged products of an interaction are absorbed in the diamond and to other background particles that fully traverse the detector.

  19. Neutron detection with noble gas scintillation: a review of recent results

    Science.gov (United States)

    Lavelle, C. M.; Coplan, Michael; Miller, Eric C.; Thompson, Alan K.; Kowler, Alex; Vest, Rob; Yue, Andrew; Koeth, Tim; Al-Sheikhly, Mohammad; Clark, Charles

    2015-08-01

    Thermal neutron detection is of vital importance to many disciplines, including neutron scattering, workplace monitoring, and homeland protection. We survey recent results from our collaboration which couple low-pressure noble gas scintillation with novel approaches to neutron absorbing materials and geometries to achieve potentially advantageous detector concepts. Noble gas scintillators were used for neutron detection as early as the late 1950's. Modern use of noble gas scintillation includes liquid and solid forms of argon and xenon in the dark matter and neutron physics experiments and commercially available high pressure applications have achieved high resolution gamma ray spectroscopy. Little attention has been paid to the overlap between low pressure noble gas scintillation and thermal neutron detection, for which there are many potential benefits.

  20. Monte Carlo based dosimetry for neutron capture therapy of brain tumors

    Science.gov (United States)

    Zaidi, Lilia; Belgaid, Mohamed; Khelifi, Rachid

    2016-11-01

    Boron Neutron Capture Therapy (BNCT) is a biologically targeted, radiation therapy for cancer which combines neutron irradiation with a tumor targeting agent labeled with a boron10 having a high thermal neutron capture cross section. The tumor area is subjected to the neutron irradiation. After a thermal neutron capture, the excited 11B nucleus fissions into an alpha particle and lithium recoil nucleus. The high Linear Energy Transfer (LET) emitted particles deposit their energy in a range of about 10μm, which is of the same order of cell diameter [1], at the same time other reactions due to neutron activation with body component are produced. In-phantom measurement of physical dose distribution is very important for BNCT planning validation. Determination of total absorbed dose requires complex calculations which were carried out using the Monte Carlo MCNP code [2].

  1. Measurement of neutron dose equivalent to proton therapy patients outside of the proton radiation field

    CERN Document Server

    Yan, X; Köhler, A; Newhauser, W D

    2002-01-01

    Measurements of neutron dose equivalent values and neutron spectral fluences close to but outside of the therapeutic proton radiation field are presented. The neutron spectral fluences were determined at five locations with Bonner sphere measurements and established by unfolding techniques. More than 50 additional neutron dose equivalent values were measured with LiI and BF sub 3 thermal neutron detectors surrounded by a 25 cm polyethylene moderating sphere. For a large-field treatment, typical values of neutron dose equivalent per therapeutic proton absorbed dose, H/D, at 50 cm distance from isocenter, range from 1 mSv/Gy (at 0 deg.with respect to the proton beam axis) to 5 mSv/Gy (at 90 deg.). Experiments reveal that H/D varies significantly with the treatment technique, e.g., patient orientation, proton beam energy, and range-modulation. The relative uncertainty in H/D values is approximately 40% (one standard deviation).

  2. Energy-Absorbing Beam Member

    Science.gov (United States)

    Littell, Justin D. (Inventor)

    2017-01-01

    An energy-absorbing (EA) beam member and having a cell core structure is positioned in an aircraft fuselage proximate to the floor of the aircraft. The cell core structure has a length oriented along a width of the fuselage, a width oriented along a length of the fuselage, and a depth extending away from the floor. The cell core structure also includes cell walls that collectively define a repeating conusoidal pattern of alternating respective larger and smaller first and second radii along the length of the cell core structure. The cell walls slope away from a direction of flight of the aircraft at a calibrated lean angle. An EA beam member may include the cell core structure and first and second plates along the length of the cell core structure on opposite edges of the cell material.

  3. Numerical simulations of quasar absorbers

    CERN Document Server

    Theuns, T

    2005-01-01

    The physical state of the intergalactic medium can be probed in great detail with the intervening absorption systems seen in quasar spectra. The properties of the Hydrogen absorbers depend on many cosmological parameters, such as the matter-power spectrum, reionisation history, ionising background and the nature of the dark matter. The spectra also contain metal lines, which can be used to constrain the star formation history and the feedback processes acting in large and small galaxies. Simulations have been instrumental in investigating to what extent these parameters can be unambiguously constrained with current and future data. This paper is meant as an introduction to this subject, and reviews techniques and methods for simulating the intergalactic medium.

  4. Warm Absorbers in Active Galactic Nuclei

    CERN Document Server

    Komossa, S

    2000-01-01

    We first provide a review of the properties of warm absorbers concentrating on what we have learned from ROSAT and ASCA. This includes dusty and dust-free warm absorbers, non-X-ray emission and absorption features of warm absorbers, and the possible warm absorber interpretation of the peculiar 1.1 keV features. We then discuss facets of warm absorbers by a more detailed investigation of individual objects: In a first part, we discuss several candidates for dusty warm absorbers. In a second part, we review and extend our earlier study of a possible relation between warm absorber and CLR in NGC 4051, and confirm that both components are of different origin (the observed coronal lines are underpredicted by the models, the warm absorber is too highly ionized). We then suggest that a potential overprediction of these lines in more lowly ionized absorbers can be avoided if these warm absorbers are dusty. In a third part, we present first results of an analysis of a deep ROSAT PSPC observation of the quasar MR2251-1...

  5. The Time Structure of Hadronic Showers in Highly Granular Calorimeters with Tungsten and Steel Absorbers

    CERN Document Server

    Adloff, C.; Chefdeville, M.; Drancourt, C.; Gaglione, R.; Geffroy, N.; Karyotakis, Y.; Koletsou, I.; Prast, J.; Vouters, G.; Repond, J.; Schlereth, J.; Xia, L.; Baldolemar, E.; Li, J.; Park, S.T.; Sosebee, M.; White, A.P.; Yu, J.; Eigen, G.; Thomson, M.A.; Ward, D.R.; Benchekroun, D.; Hoummada, A.; Khoulaki, Y.; Apostolakis, J.; Arfaoui, A.; Benoit, M.; Dannheim, D.; Elsener, K.; Folger, G.; Grefe, C.; Ivantchenko, V.; Killenberg, M.; Klempt, W.; van der Kraaij, E.; Linssen, L.; Lucaci-Timoce, A.-I.; Münnich, A.; Poss, S.; Ribon, A.; Roloff, P.; Sailer, A.; Schlatter, D.; Sicking, E.; Strube, J.; Uzhinskiy, V.; Carloganu, C.; Gay, P.; Manen, S.; Royer, L.; Cornett, U.; David, D.; Ebrahimi, A.; Falley, G.; Feege, N.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Karstensen, S.; Krivan, F.; Krüger, K.; Lu, S.; Lutz, B.; Morozov, S.; Morgunov, V.; Neubüser, C.; Reinecke, M.; Sefkow, F.; Smirnov, P.; Terwort, M.; Fagot, A.; Tytgat, M.; Zaganidis, N.; Hostachy, J.-Y.; Morin, L.; Garutti, E.; Laurien, S.; Marchesini, I.; Matysek, M.; Ramilli, M.; Briggl, K.; Eckert, P.; Harion, T.; Schultz-Coulon, H.-Ch.; Shen, W.; Stamen, R.; Chang, S.; Khan, A.; Kim, D.H.; Kong, D.J.; Oh, Y.D.; Bilki, B.; Norbeck, E.; Northacker, D.; Onel, Y.; Wilson, G.W.; Kawagoe, K.; Miyazaki, Y.; Sudo, Y.; Ueno, H.; Yoshioka, T.; Dauncey, P.D.; Cortina Gil, E.; Mannai, S.; Baulieu, G.; Calabria, P.; Caponetto, L.; Combaret, C.; Della Negra, R.; Ete, R.; Grenier, G.; Han, R.; Ianigro, J-C.; Kieffer, R.; Laktineh, I.; Lumb, N.; Mathez, H.; Mirabito, L.; Petrukhin, A.; Steen, A.; Tromeur, W.; Vander Donckt, M.; Zoccarato, Y.; Berenguer Antequera, J.; Calvo Alamillo, E.; Fouz, M.-C.; Puerta-Pelayo, J.; Corriveau, F.; Bobchenko, B.; Chadeeva, M.; Danilov, M.; Epifantsev, A.; Markin, O.; Mizuk, R.; Novikov, E.; Rusinov, V.; Tarkovsky, E.; Kozlov, V.; Soloviev, Y.; Besson, D.; Buzhan, P.; Ilyin, A.; Kantserov, V.; Kaplin, V.; Popova, E.; Tikhomirov, V.; Gabriel, M.; Kiesling, C.; Seidel, K.; Simon, F.; Soldner, C.; Szalay, M.; Tesar, M.; Weuste, L.; Amjad, M.S.; Bonis, J.; Conforti di Lorenzo, S.; Cornebise, P.; Fleury, J.; Frisson, T.; van der Kolk, N.; Richard, F.; Pöschl, R.; Rouene, J.; Anduze, M.; Balagura, V.; Becheva, E.; Boudry, V.; Brient, J-C.; Cornat, R.; Frotin, M.; Gastaldi, F.; Guliyev, E.; Haddad, Y.; Magniette, F.; Ruan, M.; Tran, T.H.; Videau, H.; Callier, S.; Dulucq, F.; Martin-Chassard, G.; de la Taille, Ch.; Raux, L.; Seguin-Moreau, N.; Zacek, J.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Ruzicka, P.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; Belhorma, B.; Ghazlane, H.; Kotera, K.; Ono, H.; Takeshita, T.; Uozumi, S.; Chai, J.S.; Song, H.S.; Lee, S.H.; Götze, M.; Sauer, J.; Weber, S.; Zeitnitz, C.

    2014-01-01

    The intrinsic time structure of hadronic showers influences the timing capability and the required integration time of hadronic calorimeters in particle physics experiments, and depends on the active medium and on the absorber of the calorimeter. With the CALICE T3B experiment, a setup of 15 small plastic scintillator tiles read out with Silicon Photomultipliers, the time structure of showers is measured on a statistical basis with high spatial and temporal resolution in sampling calorimeters with tungsten and steel absorbers. The results are compared to GEANT4 (version 9.4 patch 03) simulations with different hadronic physics models. These comparisons demonstrate the importance of using high precision treatment of low-energy neutrons for tungsten absorbers, while an overall good agreement between data and simulations for all considered models is observed for steel.

  6. The time structure of hadronic showers in highly granular calorimeters with tungsten and steel absorbers

    Science.gov (United States)

    Adloff, C.; Blaising, J.-J.; Chefdeville, M.; Drancourt, C.; Gaglione, R.; Geffroy, N.; Karyotakis, Y.; Koletsou, I.; Prast, J.; Vouters, G.; Repond, J.; Schlereth, J.; Xia, L.; Baldolemar, E.; Li, J.; Park, S. T.; Sosebee, M.; White, A. P.; Yu, J.; Eigen, G.; Thomson, M. A.; Ward, D. R.; Benchekroun, D.; Hoummada, A.; Khoulaki, Y.; Apostolakis, J.; Arfaoui, S.; Benoit, M.; Dannheim, D.; Elsener, K.; Folger, G.; Grefe, C.; Ivantchenko, V.; Killenberg, M.; Klempt, W.; van der Kraaij, E.; Linssen, L.; Lucaci-Timoce, A.-I.; Münnich, A.; Poss, S.; Ribon, A.; Roloff, P.; Sailer, A.; Schlatter, D.; Sicking, E.; Strube, J.; Uzhinskiy, V.; Cârloganu, C.; Gay, P.; Manen, S.; Royer, L.; Cornett, U.; David, D.; Ebrahimi, A.; Falley, G.; Feege, N.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Karstensen, S.; Krivan, F.; Krüger, K.; Lu, S.; Lutz, B.; Morozov, S.; Morgunov, V.; Neubüser, C.; Reinecke, M.; Sefkow, F.; Smirnov, P.; Terwort, M.; Fagot, A.; Tytgat, M.; Zaganidis, N.; Hostachy, J.-Y.; Morin, L.; Garutti, E.; Laurien, S.; Marchesini, I.; Matysek, M.; Ramilli, M.; Briggl, K.; Eckert, P.; Harion, T.; Schultz-Coulon, H.-Ch; Shen, W.; Stamen, R.; Chang, S.; Khan, A.; Kim, D. H.; Kong, D. J.; Oh, Y. D.; Bilki, B.; Norbeck, E.; Northacker, D.; Onel, Y.; Wilson, G. W.; Kawagoe, K.; Miyazaki, Y.; Sudo, Y.; Ueno, H.; Yoshioka, T.; Dauncey, P. D.; Cortina Gil, E.; Mannai, S.; Baulieu, G.; Calabria, P.; Caponetto, L.; Combaret, C.; Della Negra, R.; Eté, R.; Grenier, G.; Han, R.; Ianigro, J.-C.; Kieffer, R.; Laktineh, I.; Lumb, N.; Mathez, H.; Mirabito, L.; Petrukhin, A.; Steen, A.; Tromeur, W.; Vander Donckt, M.; Zoccarato, Y.; Berenguer Antequera, J.; Calvo Alamillo, E.; Fouz, M.-C.; Puerta-Pelayo, J.; Corriveau, F.; Bobchenko, B.; Chadeeva, M.; Danilov, M.; Epifantsev, A.; Markin, O.; Mizuk, R.; Novikov, E.; Rusinov, V.; Tarkovsky, E.; Kozlov, V.; Soloviev, Y.; Besson, D.; Buzhan, P.; Ilyin, A.; Kantserov, V.; Kaplin, V.; Popova, E.; Tikhomirov, V.; Gabriel, M.; Kiesling, C.; Seidel, K.; Simon, F.; Soldner, C.; Szalay, M.; Tesar, M.; Weuste, L.; Amjad, M. S.; Bonis, J.; Conforti di Lorenzo, S.; Cornebise, P.; Fleury, J.; Frisson, T.; van der Kolk, N.; Richard, F.; Pöschl, R.; Rouëné, J.; Anduze, M.; Balagura, V.; Becheva, E.; Boudry, V.; Brient, J.-C.; Cornat, R.; Frotin, M.; Gastaldi, F.; Guliyev, E.; Haddad, Y.; Magniette, F.; Ruan, M.; Tran, T. H.; Videau, H.; Callier, S.; Dulucq, F.; Martin-Chassard, G.; de la Taille, Ch; Raux, L.; Seguin-Moreau, N.; Zacek, J.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Ruzicka, P.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; Belhorma, B.; Ghazlane, H.; Kotera, K.; Ono, H.; Takeshita, T.; Uozumi, S.; Chai, J. S.; Song, H. S.; Lee, S. H.; Götze, M.; Sauer, J.; Weber, S.; Zeitnitz, C.

    2014-07-01

    The intrinsic time structure of hadronic showers influences the timing capability and the required integration time of hadronic calorimeters in particle physics experiments, and depends on the active medium and on the absorber of the calorimeter. With the CALICE T3B experiment, a setup of 15 small plastic scintillator tiles read out with Silicon Photomultipliers, the time structure of showers is measured on a statistical basis with high spatial and temporal resolution in sampling calorimeters with tungsten and steel absorbers. The results are compared to GEANT4 (version 9.4 patch 03) simulations with different hadronic physics models. These comparisons demonstrate the importance of using high precision treatment of low-energy neutrons for tungsten absorbers, while an overall good agreement between data and simulations for all considered models is observed for steel.

  7. Neutron sources and applications

    Energy Technology Data Exchange (ETDEWEB)

    Price, D.L. [ed.] [Argonne National Lab., IL (United States); Rush, J.J. [ed.] [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

    1994-01-01

    Review of Neutron Sources and Applications was held at Oak Brook, Illinois, during September 8--10, 1992. This review involved some 70 national and international experts in different areas of neutron research, sources, and applications. Separate working groups were asked to (1) review the current status of advanced research reactors and spallation sources; and (2) provide an update on scientific, technological, and medical applications, including neutron scattering research in a number of disciplines, isotope production, materials irradiation, and other important uses of neutron sources such as materials analysis and fundamental neutron physics. This report summarizes the findings and conclusions of the different working groups involved in the review, and contains some of the best current expertise on neutron sources and applications.

  8. The DIORAMA Neutron Emitter

    Energy Technology Data Exchange (ETDEWEB)

    Terry, James Russell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-05

    Emission of neutrons in a given event is modeled by the DioramaEmitterNeutron object, a subclass of the abstract DioramaEmitterModule object. The GenerateEmission method of this object is the entry point for generation of a neutron population for a given event. Shown in table 1, this method requires a number of parameters to be defined in the event definition.

  9. A charge-collection method for measurements of pulsed fast-neutron flux

    CERN Document Server

    Ouyang, X P; Ho, Y K; Zhang, Z B

    2002-01-01

    A charge-collection method for measuring the flux of pulsed fast neutrons in current mode has been developed, which is based on the well-known recoil-proton method combined with ion-induced secondary electron emission from solid surfaces. The detection unit consists of four elements: an n-p converter, an absorber, a collector, and a rear insulator. The assembly does not require vacuum for operation. Recoil protons from the n-p converter and the secondary electrons induced by the passing protons on the interface of the absorber and the collector contribute to the detector output signal. By properly choosing the materials and the combination of the absorber and the collector, the fraction of secondary electrons in the output signal can be determined experimentally. This detection concept allows one to design a medium type of fast-neutron detector for measurements of extremely intense pulsed neutron flux with a number of advantages over the existing systems.

  10. Neutron dosimetry, moderated energy spectrum, and neutron capture therapy for californium-252 medical sources

    Science.gov (United States)

    Rivard, Mark Joseph

    Examination of neutron dosimetry for 252Cf has been conducted using calculative and experimental means. Monte Carlo N-Particle (MCNP) transport code was used in a distributed computing environment as a parallel virtual machine (PVM) to determine the absorbed neutron dose and neutron energy spectrum from 252Cf in a variety of clinically relevant materials. Herein, a Maxwellian spectrum was used to model the 252Cf neutron emissions within these materials. 252Cf mixed-field dosimetry of Applicator Tube (AT) type sources was measured using 1.0 and 0.05 cm3 tissue-equivalent ion chambers and a miniature GM counter. A dosimetry protocol was formulated similar that of ICRU 45. The 252Cf AT neutron dosimetry was determined in the cylindrical coordinate system formalism recommended by the AAPM Task Group 43. These results demonstrated the overwhelming dependence of dosimetry on the source geometry factor as there was no significant neutron attenuation within the source or encapsulation. Gold foils and TLDs were used to measure the thermal flux in the vicinity of 252Cf AT sources to compare with the results calculated using MCNP. As the fast neutron energy spectrum did not markedly changed at increasing distances from the AT source, neutron dosimetry results obtained with paired ion chambers using fixed sensitivity factors agreed well with MCNP results and those in the literature. Calculations of moderated 252Cf neutron energy spectrum with various loadings of 10B and 157Gd were performed, in addition to analysis of neutron capture therapy dosimetry with these isotopes. Radiological concerns such as personnel exposure and shielding of 252Cf emissions were examined. Feasibility of a high specific-activity 252Cf HDR source was investigated through radiochemical and metallurgical studies using stand-ins such as Tb, Gd and 249Cf. Issues such as capsule burst strength due to helium production for a variety of proposed HDR sources were addressed. A recommended 252Cf source

  11. Neutron scattering. Experiment manuals

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2014-07-01

    The following topics are dealt with: The thermal triple-axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot-single-crystal diffractometer HEiDi, the three-axis spectrometer PANDA, the backscattering spectrometer SPHERES, the DNS neutron-polarization analysis, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering at KWS-1 and KWS-2, a very-small-angle neutron scattering diffractometer with focusing mirror, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  12. Neutron-emission measurements at a white neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Haight, Robert C [Los Alamos National Laboratory

    2010-01-01

    Data on the spectrum of neutrons emittcd from neutron-induced reactions are important in basic nuclear physics and in applications. Our program studies neutron emission from inelastic scattering as well as fission neutron spectra. A ''white'' neutron source (continuous in energy) allows measurements over a wide range of neutron energies all in one experiment. We use the tast neutron source at the Los Alamos Neutron Science Center for incident neutron energies from 0.5 MeV to 200 MeV These experiments are based on double time-of-flight techniques to determine the energies of the incident and emitted neutrons. For the fission neutron measurements, parallel-plate ionization or avalanche detectors identify fission in actinide samples and give the required fast timing pulse. For inelastic scattering, gamma-ray detectors provide the timing and energy spectroscopy. A large neutron-detector array detects the emitted neutrons. Time-of-flight techniques are used to measure the energies of both the incident and emitted neutrons. Design considerations for the array include neutron-gamma discrimination, neutron energy resolution, angular coverage, segmentation, detector efficiency calibration and data acquisition. We have made preliminary measurements of the fission neutron spectra from {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu. Neutron emission spectra from inelastic scattering on iron and nickel have also been investigated. The results obtained will be compared with evaluated data.

  13. Multiband Negative Permittivity Metamaterials and Absorbers

    Directory of Open Access Journals (Sweden)

    Yiran Tian

    2013-01-01

    Full Text Available Design and characteristics of multiband negative permittivity metamaterial and its absorber configuration are presented in this paper. The proposed multiband metamaterial is composed of a novel multibranch resonator which can possess four electric resonance frequencies. It is shown that, by controlling the length of the main branches of such resonator, the resonant frequencies and corresponding absorbing bands of metamaterial absorber can be shifted in a large frequency band.

  14. Multiobjective Topology Optimization of Energy Absorbing Materials

    Science.gov (United States)

    2015-08-01

    125–143 DOI 10.1007/s00158-014-1117-8 RESEARCH PAPER Multiobjective topology optimization of energy absorbing materials Raymond A. Wildman · George A...recent developments. J Multiscale Model 3(4):1–42 Qiao P, Yang M, Bobaru F (2008) Impact mechanics and high-energy absorbing materials: review . J Aerosp...ARL-RP-0533 ● AUG 2015 US Army Research Laboratory Multiobjective Topology Optimization of Energy Absorbing Materials by

  15. New detectors of neutron, gamma- and X-radiations

    CERN Document Server

    Lobanov, N S

    2002-01-01

    Paper presents new detectors to record absorbed doses of neutron, gamma- and X-ray radiations within 0-1500 Mrad range. DBF dosimeter is based on dibutyl phthalate. EDS dosimeter is based on epoxy (epoxide) resin, while SD 5-40 detector is based on a mixture of dibutyl phthalate and epoxy resin. Paper describes experimental techniques to calibrate and interprets the measurement results of absorbed doses for all detectors. All three detectors cover 0-30000 Mrad measured does range. The accuracy of measurements is +- 10% independent (practically) of irradiation dose rates within 20-2000 rad/s limits under 20-80 deg C temperature

  16. A Six-Fold Symmetric Metamaterial Absorber

    Directory of Open Access Journals (Sweden)

    Humberto Fernández Álvarez

    2015-04-01

    Full Text Available A novel microwave metamaterial absorber design is introduced along with its manufacturing and characterization. Significant results considering both bandwidth and angular stability are achieved. Parametric analysis and simplified equivalent circuit are provided to give an insight on the key elements influencing the absorber performance. In addition, the constitutive parameters of the effective medium model are obtained and related to the absorber resonant behavior. Moreover, a new thinner and more flexible absorber version, preserving broad bandwidth and angular insensitive performance, is simulated, and an 8 × 8 unit-cells prototype is manufactured and measured for a limited angular margin in an anechoic chamber.

  17. Nonlinear dynamic vibration absorbers with a saturation

    Science.gov (United States)

    Febbo, M.; Machado, S. P.

    2013-03-01

    The behavior of a new type of nonlinear dynamic vibration absorber is studied. A distinctive characteristic of the proposed absorber is the impossibility to extend the system to infinity. The mathematical formulation is based on a finite extensibility nonlinear elastic potential to model the saturable nonlinearity. The absorber is attached to a single degree-of-freedom linear/nonlinear oscillator subjected to a periodic external excitation. In order to solve the equations of motion and to analyze the frequency-response curves, the method of averaging is used. The performance of the FENE absorber is evaluated considering a variation of the nonlinearity of the primary system, the damping and the linearized frequency of the absorber and the mass ratio. The numerical results show that the proposed absorber has a very good efficiency when the nonlinearity of the primary system increases. When compared with a cubic nonlinear absorber, for a large nonlinearity of the primary system, the FENE absorber shows a better effectiveness for the whole studied frequency range. A complete absence of quasi-periodic oscillations is also found for an appropriate selection of the parameters of the absorber. Finally, direct integrations of the equations of motion are performed to verify the accuracy of the proposed method.

  18. Absorbent product and articles made therefrom

    Science.gov (United States)

    Dawn, F. S.; Correale, J. V. (Inventor)

    1982-01-01

    A multilayer absorbent product for use in contact with the skin to absorb fluids is described. The product has a water pervious facing layer for contacting the skin, and a first fibrous wicking layer overlaying the water pervious layer. A first container section is defined by inner and outer layers of a water pervious wicking material in between a first absorbent mass and a second container section defined by inner and outer layers of a water pervious wicking material between what is disposed a second absorbent mass, and a liquid impermeable/gas permeable layer overlaying the second fibrous wicking layer.

  19. Metamaterial absorber with random dendritic cells

    Science.gov (United States)

    Zhu, Weiren; Zhao, Xiaopeng

    2010-05-01

    The metamaterial absorber composed of random dendritic cells has been investigated at microwave frequencies. It is found that the absorptivities come to be weaker and the resonant frequency get red shift as the disordered states increasing, however, the random metamaterial absorber still presents high absorptivity more than 95%. The disordered structures can help understanding of the metamaterial absorber and may be employed for practical design of infrared metamaterial absorber, which may play important roles in collection of radiative heat energy and directional transfer enhancement.

  20. Characteristics and application of spherical-type activation detectors in neutron spectrum measurements at a boron neutron capture therapy (BNCT) facility

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Heng-Xiao; Chen, Wei-Lin [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300, Taiwan, ROC (China); Liu, Yuan-Hao [Neuboron Medtech Ltd., Nanjing, Jiangsu Province 21112 (China); Sheu, Rong-Jiun, E-mail: rjsheu@mx.nthu.edu.tw [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300, Taiwan, ROC (China); Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300, Taiwan, ROC (China)

    2016-03-01

    A set of spherical-type activation detectors was developed aiming to provide better determination of the neutron spectrum at the Tsing Hua Open-pool Reactor (THOR) BNCT facility. An activation foil embedded in a specially designed spherical holder exhibits three advantages: (1) minimizing the effect of neutron angular dependence, (2) creating response functions with broadened coverage of neutron energies by introducing additional moderators or absorbers to the central activation foil, and (3) reducing irradiation time because of improved detection efficiencies to epithermal neutron beam. This paper presents the design concept and the calculated response functions of new detectors. Theoretical and experimental demonstrations of the performance of the detectors are provided through comparisons of the unfolded neutron spectra determined using this method and conventional multiple-foil activation techniques.

  1. Neutrons characterization of the nuclear reactor Ian-R1 of Colombia; Caracterizacion de los neutrones del reactor nuclear IAN-R1 de Colombia

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez P, L. X.; Martinez O, S. A. [Universidad Pedagogica y Tecnologica de Colombia, Grupo de Fisica Nuclear Aplicada y Simulacion, Carretera Central del Norte Km. 1, Via Paipa, 150003 Tunja, Boyaca (Colombia); Vega C, H. R., E-mail: s.agustin.martinez@uptc.edu.co [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2014-08-15

    By means of Monte Carlo methods, with the code MCNPX, the neutron characteristics of the research nuclear reactor Ian-R1 of Colombia, in power off but with the neutrons source in their start position, have been valued. The neutrons spectra, the total flow and their average power were calculated in the irradiation spaces inside the graphite reflector, as well as in the cells with air. Also the spectra, the total flow and the absorbed dose were calculated in several places distributed along the radial shaft inside the water moderator. The neutrons total flow was also considered to the long of the axial shaft. The characteristics of the neutrons spectra vary depending on their position regarding the source and the material that surrounds to the cell where the calculation was made. (Author)

  2. Transport of ultracold neutrons through a mirror system with surface roughness as a velocity filter

    CERN Document Server

    Chizhova, L A; Jenke, T; Cronenberg, G; Geltenbort, P; Abele, H; Burgdörfer, J

    2012-01-01

    We perform classical Monte Carlo simulations of ultracold neutron transport through an absorbing-reflecting mirror system in the Earth's gravitational field. We show that the underlying mixed phase space of regular skipping motion and random motion due to disorder scattering can be exploited to realize a velocity filter for ultracold neutrons. The range of velocities selected is controlled by geometric parameters of the wave guide. Possible applications include investigations of transport and scattering dynamics in confined systems.

  3. Neutron flux reduction programs for reactor pressure vessel

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, C.S. [Korea Atomic Energy Research Inst. KAERI, 150 Deogjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Kim, B.C. [Korea Reactor Integrity Surveillance Technology KRIST, 150 Deogjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

    2011-07-01

    The objective of this work is to implement various fast neutron flux reduction programs on the belt-line region of the reactor pressure vessel to reduce the increasing rate of reference temperature for pressurized thermal shock (RT PTS) for Korea Nuclear Unit 1. A pressurized thermal shock (PTS) event is an event or transient in pressurized water reactors (PWRs) causing severe overcooling (thermal shock) concurrent with or followed by significant pressure in the reactor vessel. A PTS concern arises if one of these transients acts in the belt-line region of a reactor vessel where a reduced fracture resistance exists because of neutron irradiation. Generally, the RT PTS value is continuously increasing according to the fast neutron irradiation during the reactor operation, and it can reach the screening criterion prior to the expiration of the operating license. To reduce the increasing rate of RT PTS, various neutron flux reduction programs can be implemented, which are focused on license renewal. In this paper, neutron flux reduction programs, such as low leakage loading pattern strategy, loading of neutron absorber rods, and dummy fuel assembly loading are considered for Korea Nuclear Unit 1, of which the RT PTS value of the leading material (circumferential weld) is going to reach the screening criterion in the near future. To evaluate the effects of the neutron flux reduction programs, plant and cycle specific forward neutron transport calculations for the various neutron flux reduction programs were carried out. For the analysis, all transport calculations were carried out by using the DORT 3.1 discrete ordinate code and BUGLE-96 cross-section library. (authors)

  4. Neutron resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gunsing, F

    2005-06-15

    The present document has been written in order to obtain the diploma 'Habilitation a Diriger des Recherches'. Since this diploma is indispensable to supervise thesis students, I had the intention to write a document that can be useful for someone starting in the field of neutron resonance spectroscopy. Although the here described topics are already described elsewhere, and often in more detail, it seemed useful to have most of the relevant information in a single document. A general introduction places the topic of neutron-nucleus interaction in a nuclear physics context. The large variations of several orders of magnitude in neutron-induced reaction cross sections are explained in terms of nuclear level excitations. The random character of the resonances make nuclear model calculation predictions impossible. Then several fields in physics where neutron-induced reactions are important and to which I have contributed in some way or another, are mentioned in a first synthetic chapter. They concern topics like parity nonconservation in certain neutron resonances, stellar nucleosynthesis by neutron capture, and data for nuclear energy applications. The latter item is especially important for the transmutation of nuclear waste and for alternative fuel cycles. Nuclear data libraries are also briefly mentioned. A second chapter details the R-matrix theory. This formalism is the foundation of the description of the neutron-nucleus interaction and is present in all fields of neutron resonance spectroscopy. (author)

  5. Development of Neutron Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Hee; Lee, J. S.; Seong, B. S. (and others)

    2007-06-15

    Neutron spectrometers which are used in the basic researches such as physics, chemistry and materials science and applied in the industry were developed at the horizontal beam port of HANARO reactor. In addition, the development of core components for neutron scattering and the upgrade of existing facilities are also performed. The vertical neutron reflectometer was fabricated and installed at ST3 beam port. The performance test of the reflectometer was completed and the reflectometer was opened to users. The several core parts and options were added in the polarized neutron spectrometer. The horizontal neutron reflectometer from Brookhaven National Laboratory was moved to HANARO and installed, and the performance of the reflectometer was examined. The HIPD was developed and the performance test was completed. The base shielding for TAS was fabricated. The soller collimator, Cu mosaic monochromator, Si BPC monochromator and position sensitive detector were developed and applied in the neutron spectrometer as part of core component development activities. In addition, the sputtering machine for mirror device are fabricated and the neutron mirror is made using the sputtering machine. The FCD was upgraded and the performance of the FCD are improved over the factor of 10. The integration and upgrade of the neutron detection system were also performed.

  6. Neutron Star Matter

    CERN Document Server

    Wambach, Jochen

    2013-01-01

    In this presentation I discuss two aspects of the neutron-matter equation of state. One relates to the symmetry energy of nuclear matter and empirical constraints on its slope parameter at saturation density. The second deals with spatially inhomogeneous chiral phases of deconfined quark matter in the inner core of a neutron star.

  7. Neutron Multiplicity Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Frame, Katherine Chiyoko [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-28

    Neutron multiplicity measurements are widely used for nondestructive assay (NDA) of special nuclear material (SNM). When combined with isotopic composition information, neutron multiplicity analysis can be used to estimate the spontaneous fission rate and leakage multiplication of SNM. When combined with isotopic information, the total mass of fissile material can also be determined. This presentation provides an overview of this technique.

  8. Neutron capture therapies

    Energy Technology Data Exchange (ETDEWEB)

    Yanch, Jacquelyn C. (Cambridge, MA); Shefer, Ruth E. (Newton, MA); Klinkowstein, Robert E. (Winchester, MA)

    1999-01-01

    In one embodiment there is provided an application of the .sup.10 B(n,.alpha.).sup.7 Li nuclear reaction or other neutron capture reactions for the treatment of rheumatoid arthritis. This application, called Boron Neutron Capture Synovectomy (BNCS), requires substantially altered demands on neutron beam design than for instance treatment of deep seated tumors. Considerations for neutron beam design for the treatment of arthritic joints via BNCS are provided for, and comparisons with the design requirements for Boron Neutron Capture Therapy (BNCT) of tumors are made. In addition, exemplary moderator/reflector assemblies are provided which produce intense, high-quality neutron beams based on (p,n) accelerator-based reactions. In another embodiment there is provided the use of deuteron-based charged particle reactions to be used as sources for epithermal or thermal neutron beams for neutron capture therapies. Many d,n reactions (e.g. using deuterium, tritium or beryllium targets) are very prolific at relatively low deuteron energies.

  9. Neutron capture therapies

    Energy Technology Data Exchange (ETDEWEB)

    Yanch, J.C.; Shefer, R.E.; Klinkowstein, R.E.

    1999-11-02

    In one embodiment there is provided an application of the {sup 10}B(n,{alpha}){sup 7}Li nuclear reaction or other neutron capture reactions for the treatment of rheumatoid arthritis. This application, called Boron Neutron Capture Synovectomy (BNCS), requires substantially altered demands on neutron beam design than for instance treatment of deep seated tumors. Considerations for neutron beam design for the treatment of arthritic joints via BNCS are provided for, and comparisons with the design requirements for Boron Neutron Capture Therapy (BNCT) of tumors are made. In addition, exemplary moderator/reflector assemblies are provided which produce intense, high-quality neutron beams based on (p,n) accelerator-based reactions. In another embodiment there is provided the use of deuteron-based charged particle reactions to be used as sources for epithermal or thermal neutron beams for neutron capture therapies. Many d,n reactions (e.g. using deuterium, tritium or beryllium targets) are very prolific at relatively low deuteron energies.

  10. In-Situ Spectrometry of Neutrons

    Science.gov (United States)

    Maurer, Richard H.

    1999-01-01

    High energy charged particles of extra-galactic, galactic and solar origin collide with spacecraft structures in Earth orbit outside the atmosphere and in interplanetary travel beyond the Earth's magnetosphere. These primaries create a number of secondary particles inside the structures that can produce a significant ionizing radiation environment. This radiation is a threat to long term inhabitants or travelers for space missions and produces an increased risk of cancer and DNA damage. The primary high energy cosmic rays and trapped protons collide with common spacecraft materials such as aluminum and silicon and create secondary particles inside structures that are mostly protons and neutrons. Charged protons are readily detected and instruments are already in existence for this task. Neutrons are electrically neutral and therefore much more difficult to measure and detect. These neutrons are reported to contribute 30-60% of the dose inside space structures and cannot be ignored. Currently there is no compact, portable and real time neutron detector instrumentation available for use inside spacecraft or on planetary surfaces where astronauts will live and work. We propose to design and build a portable, low power and robust neutron spectrometer that will measure the neutron spectrum from 10 KeV to 500 MeV with at least 10% energy resolution in the various energy intervals. This instrument will monitor the existing neutron environment both inside spacecraft structures and on planetary surfaces to determine the safest living areas, warn of high fluxes associated with solar storms and assist the NSBRI Radiation Effects Team in making an accurate assessment of increased cancer risk and DNA damage to astronauts. The instrument uses a highly efficient proportional counter Helium 3 tube at the lowest energy intervals where .equivalent damage factors for tissue are the highest (10 KeV-2 MeV). The Helium 3 tube may be shielded with a cadmium absorber to eliminate the much

  11. Inside HOLMES experiment: 163Ho metallic target production for the micro-calorimeter absorber

    Science.gov (United States)

    Pizzigoni, G.; Alpert, B.; Balata, M.; Bennett, D.; Biasotti, M.; Boragno, C.; Brofferio, C.; De Gerone, M.; Dressler, R.; Faverazani, M.; Ferri, E.; Folwer, J.; Gatti, F.; Giachero, A.; Heinitz, S.; Hilton, G.; Köster, U.; Lusignoli, M.; Maino, M.; Mates, J.; Nisi, S.; Nizzolo, R.; Nucciotti, A.; Pessina, G.; Puiu, A.; Ragazzi, S.; Reintsema, C.; Ribeiro Gomes, M.; Shmidt, D.; Schumann, D.; Sisti, M.; Swetz, D.; Terranova, F.; Ullom, J.; Day, P. K.

    2016-07-01

    The main goal in the HOLMES experiment is the neutrino mass measurement using an array of 1000 micro-calorimeters with standard metallic absorber. A good isotope for such measurement is the 163Ho, those isotopes embedded in the metallic absorber will be 1011-1013. Since 163Ho is not available in nature, a dedicated process must be set up to produce the amount needed for this neutrino mass experiment. The process with the highest born-up cross-section is the neutron irradiation of Er2O3 enriched in 162Er: 162Er(n,γ)163Er →163Ho+νe, where the decay is an EC with half-life of about 75 min and the (n,γ) is about 20 barns for thermal neutron. After the neutron irradiation in the oxide powder there are several radioactive isotopes which are potentially disturbing because of the background that they cause below 5 keV. The chemical separation of holmium from the irradiation enriched Er2O3 powder is therefore mandatory and will be performed by means of ion exchange chromatography. On the end of those processes the oxide powder enriched in 162Er will have the 163Ho isotope number required. The holmium chemical state influences the end point of the EC spectrum, in order to avoid such effect it is necessary to embed in the absorber only the metallic isotope. Reduction and distillation technique allowed us to obtain a pure metallic holmium, starting from natural oxide holmium. This technique will be applied on the irradiated oxide powder to obtain the metallic 163Ho, ready to be embedded in the micro-calorimeter absorber.

  12. Neutron Stars and Pulsars

    CERN Document Server

    Becker, Werner

    2009-01-01

    Neutron stars are the most compact astronomical objects in the universe which are accessible by direct observation. Studying neutron stars means studying physics in regimes unattainable in any terrestrial laboratory. Understanding their observed complex phenomena requires a wide range of scientific disciplines, including the nuclear and condensed matter physics of very dense matter in neutron star interiors, plasma physics and quantum electrodynamics of magnetospheres, and the relativistic magneto-hydrodynamics of electron-positron pulsar winds interacting with some ambient medium. Not to mention the test bed neutron stars provide for general relativity theories, and their importance as potential sources of gravitational waves. It is this variety of disciplines which, among others, makes neutron star research so fascinating, not only for those who have been working in the field for many years but also for students and young scientists. The aim of this book is to serve as a reference work which not only review...

  13. THERMAL NEUTRON BACKSCATTER IMAGING.

    Energy Technology Data Exchange (ETDEWEB)

    VANIER,P.; FORMAN,L.; HUNTER,S.; HARRIS,E.; SMITH,G.

    2004-10-16

    Objects of various shapes, with some appreciable hydrogen content, were exposed to fast neutrons from a pulsed D-T generator, resulting in a partially-moderated spectrum of backscattered neutrons. The thermal component of the backscatter was used to form images of the objects by means of a coded aperture thermal neutron imaging system. Timing signals from the neutron generator were used to gate the detection system so as to record only events consistent with thermal neutrons traveling the distance between the target and the detector. It was shown that this time-of-flight method provided a significant improvement in image contrast compared to counting all events detected by the position-sensitive {sup 3}He proportional chamber used in the imager. The technique may have application in the detection and shape-determination of land mines, particularly non-metallic types.

  14. Pocked surface neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, Douglas (Whitmore Lake, MI); Klann, Raymond (Bolingbrook, IL)

    2003-04-08

    The detection efficiency, or sensitivity, of a neutron detector material such as of Si, SiC, amorphous Si, GaAs, or diamond is substantially increased by forming one or more cavities, or holes, in its surface. A neutron reactive material such as of elemental, or any compound of, .sup.10 B, .sup.6 Li, .sup.6 LiF, U, or Gd is deposited on the surface of the detector material so as to be disposed within the cavities therein. The portions of the neutron reactive material extending into the detector material substantially increase the probability of an energetic neutron reaction product in the form of a charged particle being directed into and detected by the neutron detector material.

  15. Neutron stars - General review

    Science.gov (United States)

    Cameron, A. G. W.; Canuto, V.

    1974-01-01

    A review is presented of those properties of neutron stars upon which there is general agreement and of those areas which currently remain in doubt. Developments in theoretical physics of neutron star interiors are summarized with particular attention devoted to hyperon interactions and the structure of interior layers. Determination of energy states and the composition of matter is described for successive layers, beginning with the surface and proceeding through the central region into the core. Problems encountered in determining the behavior of matter in the ultra-high density regime are discussed, and the effects of the magnetic field of a neutron star are evaluated along with the behavior of atomic structures in the field. The evolution of a neutron star is outlined with discussion centering on carbon detonation, cooling, vibrational damping, rotation, and pulsar glitches. The role of neutron stars in cosmic-ray propagation is considered.

  16. Comments on liquid hydrogen absorbers for MICE

    Energy Technology Data Exchange (ETDEWEB)

    Green, Michael A.

    2003-02-01

    This report describes the heat transfer problems associatedwith a liquid hydrogen absorber for the MICE experiment. This reportdescribes a technique for modeling heat transfer from the outside world,to the abosrber case and in its vacuum vessel, to the hydrogen and theninto helium gas at 14 K. Also presented are the equation for freeconvection cooling of the liquid hydrogen in the absorber.

  17. An ultrathin dual-band metamaterial absorber

    Science.gov (United States)

    Zhang, Yong; Duan, Junping; Zhang, Wendong; Wang, Wanjun; Zhang, Binzhen

    2016-10-01

    The design and preparation of an ultrathin dual-band metamaterial absorber whose resonant frequency located at radar wave (20 GHz-60 GHz) is presented in this paper. The absorber is composed of a 2-D periodic sandwich featured with two concentric annuluses. The influence on the absorber's performance produced by resonant cell's structure size and material parameters was numerically simulated and analyzed based on the standard full wave finite integration technology in CST. Laser ablation process was adopted to prepare the designed absorber on epoxy resin board coated with on double plane of copper with a thickness that is 1/30 and 1/50 of the resonant wavelength at a resonant frequency of 30.51 GHz and 48.15 GHz. The full width at half maximum (FWHM) reached 2.2 GHz and 2.35 GHz and the peak of the absorptance reached 99.977%. The ultrathin absorber is nearly omnidirectional for all polarizations. The test results of prepared sample testify the designed absorber's excellent absorbing performance forcefully. The absorber expands inspirations of radar stealth in military domain due to its flexible design, cost-effective and other outstanding properties.

  18. 21 CFR 872.6050 - Saliva absorber.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Saliva absorber. 872.6050 Section 872.6050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6050 Saliva absorber. (a) Identification. A saliva...

  19. Tuned mass absorber on a flexible structure

    DEFF Research Database (Denmark)

    Krenk, Steen; Høgsberg, Jan Becker

    2014-01-01

    The classic design of a tuned mass absorber is based on a simple two-mass analogy in which the tuned mass is connected to the structural mass with a spring and a viscous damper. In a flexible multi-degree-of-freedom structure the tuned mass absorber is typically introduced to provide damping of a...

  20. SINGLE CRYSTAL NEUTRON DIFFRACTION.

    Energy Technology Data Exchange (ETDEWEB)

    KOETZLE,T.F.

    2001-03-13

    Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.

  1. Optical polarizing neutron devices designed for pulsed neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, M.; Kurahashi, K.; Endoh, Y. [Tohoku Univ, Sendai (Japan); Itoh, S. [National Lab. for High Energy Physics, Tsukuba (Japan)

    1997-09-01

    We have designed two polarizing neutron devices for pulsed cold neutrons. The devices have been tested at the pulsed neutron source at the Booster Synchrotron Utilization Facility of the National Laboratory for High Energy Physics. These two devices proved to have a practical use for experiments to investigate condensed matter physics using pulsed cold polarized neutrons.

  2. [Absorbed doses in dental radiology].

    Science.gov (United States)

    Bianchi, S D; Roccuzzo, M; Albrito, F; Ragona, R; Anglesio, S

    1996-01-01

    The growing use of dento-maxillo-facial radiographic examinations has been accompanied by the publication of a large number of studies on dosimetry. A thorough review of the literature is presented in this article. Most studies were carried out on tissue equivalent skull phantoms, while only a few were in vivo. The aim of the present study was to evaluate in vivo absorbed doses during Orthopantomography (OPT). Full Mouth Periapical Examination (FMPE) and Intraoral Tube Panoramic Radiography (ITPR). Measurements were made on 30 patients, reproducing clinical conditions, in 46 anatomical sites, with 24 intra- and 22 extra-oral thermoluminiscent dosimeters (TLDS). The highest doses were measured, in orthopantomography, at the right mandibular angle (1899 mu Gy) in FMPE on the right naso-labial fold (5640 mu Gy and in ITPR on the palatal surface of the left second upper molar (1936 mu Gy). Intraoral doses ranged from 21 mu Gy, in orthopantomography, to 4494 mu Gy in FMPE. Standard errors ranged from 142% in ITPR to 5% in orthopantomography. The highest rate of standard errors was found in FMPE and ITPR. The data collected in this trial are in agreement with others in major literature reports. Disagreements are probably due to different exam acquisition and data collections. Such differences, presented comparison in several sites, justify lower doses in FMPE and ITPR. Advantages and disadvantages of in vivo dosimetry of the maxillary region are discussed, the former being a close resemblance to clinical conditions of examination and the latter the impossibility of collecting values in depth of tissues. Finally, both ITPR and FMPE required lower doses than expected, and can be therefore reconsidered relative to their radiation risk.

  3. Active neutron methods for nuclear safeguards applications using Helium-4 gas scintillation detectors

    Science.gov (United States)

    Lewis, Jason M.

    Active neutron methods use a neutron source to interrogate fissionable material. In this work a 4He gas scintillation fast neutron detection system is used to measure neutrons created by the interrogation. Three new applications of this method are developed: spent nuclear fuel assay, fission rate measurement, and special nuclear material detection. Three active neutron methods are included in this thesis. First a non-destructive plutonium assay technique called Multispectral Active Neutron Interrogation Analysis is developed. It is based on interrogating fuel with neutrons at several different energies. The induced fission rates at each interrogation energy are compared with results from a neutron transport model of the irradiation geometry in a system of equations to iteratively solve the inverse problem for isotopic composition. The model is shown to converge on the correct composition for a material with 3 different fissionable components, a representative neutron absorber, and any neutron transparent material such as oxygen in a variety of geometries. Next an experimental fission rate measurement technique is developed using 4He gas scintillation fast neutron detector. Several unique features of this detector allow it to detect and provide energy information on fast neutrons with excellent gamma discrimination efficiency. The detector can measure induced fission rate by energetically differentiating between interrogation neutrons and higher energy fission neutrons. The detector response to a mono-energetic deuterium-deuterium fusion neutron generator and a 252Cf source are compared to examine the difference in detected energy range. Finally we demonstrate a special nuclear material detection technique by detecting an unambiguous fission neutron signal produced in natural uranium during active neutron interrogation using a deuterium-deuterium neutron generator and a high pressure 4He gas fast neutron scintillation detector. Energy histograms resulting from this

  4. Fast neutrons set the pace. [Radiobiological investigations with fast neutrons at the CSIR cyclotron in Pretoria

    Energy Technology Data Exchange (ETDEWEB)

    Hough, J.H.; Slabbert, J.P. (Council for Scientific and Industrial Research, Pretoria (South Africa). National Accelerator Centre)

    1985-01-01

    Radiobiological investigations with fast neutrons have been initiated at the CSIR cyclotron in Pretoria. It was proposed some years ago to create a neutron therapy facility using the CSIR cyclotron. Neutrons are classified as high linear energy transfer (LET) particles. Biological damage occurring in tissue is a direct function of the LET of the incident radiation. To quantify the biological effects of different types of radiation on mammalian cells, several procedures and concepts have evolved from radiobiological research. Probably the most significant laboratory techniques developed, were the derivation of cell survival curves which are obtained by determining the number of cell colonies that have survived a certain radiation dose. A semi-logarithmic plot of surviving fraction versus the absorbed dose yields the survival curve. Dose modifying factors such as the relative biological effectiveness (RBE) of the radiation can be quantified in terms of this relationship. A radiobiological programme has to be undertaken before patients can receive neutron therapy at the CSIR cyclotron. The article is a discussion of this programme.

  5. Performance characteristics of the MIT fission converter based epithermal neutron beam.

    Science.gov (United States)

    Riley, K J; Binns, P J; Harling, O K

    2003-04-07

    A pre-clinical characterization of the first fission converter based epithermal neutron beam (FCB) designed for boron neutron capture therapy (BNCT) has been performed. Calculated design parameters describing the physical performance of the aluminium and Teflon filtered beam were confirmed from neutron fluence and absorbed dose rate measurements performed with activation foils and paired ionization chambers. The facility currently provides an epithermal neutron flux of 4.6 x 10(9) n cm(-2) s(-1) in-air at the patient position that makes it the most intense BNCT source in the world. This epithermal neutron flux is accompanied by very low specific photon and fast neutron absorbed doses of 3.5 +/- 0.5 and 1.4 +/- 0.2 x 10(-13) Gy cm2, respectively. A therapeutic dose rate of 1.7 RBE Gy min(-1) is achievable at the advantage depth of 97 mm when boronated phenylalanine (BPA) is used as the delivery agent, giving an average therapeutic ratio of 5.7. In clinical trials of normal tissue tolerance when using the FCB, the effective prescribed dose is due principally to neutron interactions with the nonselectively absorbed BPA present in brain. If an advanced compound is considered, the dose to brain would instead be predominately from the photon kerma induced by thermal neutron capture in hydrogen and advantage parameters of 0.88 Gy min(-1), 121 mm and 10.8 would be realized for the therapeutic dose rate, advantage depth and therapeutic ratio, respectively. This study confirms the success of a new approach to producing a high intensity, high purity epithermal neutron source that attains near optimal physical performance and which is well suited to exploit the next generation of boron delivery agents.

  6. Fail-safe neutron shutter used for thermal neutron radiography

    Energy Technology Data Exchange (ETDEWEB)

    Sachs, R.D.; Morris, R.A.

    1976-11-01

    A fail-safe, reliable, easy-to-use neutron shutter was designed, built, and put into operation at the Omega West Reactor, Los Alamos Scientific Laboratory. The neutron shutter will be used primarily to perform thermal neutron radiography, but is also available for a highly collimated source of thermal neutrons (neutron flux = 3.876 x 10/sup 6/ (neutrons)/(cm/sup 2/.s)). Neutron collimator sizes of either 10.16 by 10.16 cm or 10.16 by 30.48 cm are available.

  7. Design of a nonlinear torsional vibration absorber

    Science.gov (United States)

    Tahir, Ammaar Bin

    Tuned mass dampers (TMD) utilizing linear spring mechanisms to mitigate destructive vibrations are commonly used in practice. A TMD is usually tuned for a specific resonant frequency or an operating frequency of a system. Recently, nonlinear vibration absorbers attracted attention of researchers due to some potential advantages they possess over the TMDs. The nonlinear vibration absorber, or the nonlinear energy sink (NES), has an advantage of being effective over a broad range of excitation frequencies, which makes it more suitable for systems with several resonant frequencies, or for a system with varying excitation frequency. Vibration dissipation mechanism in an NES is passive and ensures that there is no energy backflow to the primary system. In this study, an experimental setup of a rotational system has been designed for validation of the concept of nonlinear torsional vibration absorber with geometrically induced cubic stiffness nonlinearity. Dimensions of the primary system have been optimized so as to get the first natural frequency of the system to be fairly low. This was done in order to excite the dynamic system for torsional vibration response by the available motor. Experiments have been performed to obtain the modal parameters of the system. Based on the obtained modal parameters, the design optimization of the nonlinear torsional vibration absorber was carried out using an equivalent 2-DOF modal model. The optimality criterion was chosen to be maximization of energy dissipation in the nonlinear absorber attached to the equivalent 2-DOF system. The optimized design parameters of the nonlinear absorber were tested on the original 5-DOF system numerically. A comparison was made between the performance of linear and nonlinear absorbers using the numerical models. The comparison showed the superiority of the nonlinear absorber over its linear counterpart for the given set of primary system parameters as the vibration energy dissipation in the former is

  8. Neutron detection using a current biased kinetic inductance detector

    Energy Technology Data Exchange (ETDEWEB)

    Shishido, Hiroaki, E-mail: shishido@pe.osakafu-u.ac.jp; Miyajima, Shigeyuki; Ishida, Takekazu [Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Institute for Nanofabrication Research, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Narukami, Yoshito [Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Arai, Masatoshi [Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Hidaka, Mutsuo [National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan); Fujimaki, Akira [Department of Quantum Engineering, Nagoya University, Nagoya, Aichi 464-8603 (Japan)

    2015-12-07

    We demonstrate neutron detection using a solid state superconducting current biased kinetic inductance detector (CB-KID), which consists of a superconducting Nb meander line of 1 μm width and 40 nm thickness. {sup 10}B-enriched neutron absorber layer of 150 nm thickness is placed on top of the CB-KID. Our neutron detectors are able to operate in a wide superconducting region in the bias current–temperature diagram. This is in sharp contrast with our preceding current-biased transition edge detector, which can operate only in a narrow range just below the superconducting critical temperature. The full width at half maximum of the signals remains of the order of a few tens of ns, which confirms the high speed operation of our detectors.

  9. Targets for bulk hydrogen analysis using thermal neutrons

    CERN Document Server

    Csikai, J; Buczko, C M

    2002-01-01

    The reflection property of substances can be characterized by the reflection cross-section of thermal neutrons, sigma subbeta. A combination of the targets with thin polyethylene foils allowed an estimation of the flux depression of thermal neutrons caused by a bulk sample containing highly absorbing elements or compounds. Some new and more accurate sigma subbeta values were determined by using the combined target arrangement. For the ratio, R of the reflection and the elastic scattering cross-sections of thermal neutrons, R=sigma subbeta/sigma sub E sub L a value of 0.60+-0.02 was found on the basis of the data obtained for a number of elements from H to Pb. Using this correlation factor, and the sigma sub E sub L values, the unknown sigma subbeta data can be deduced. The equivalent thicknesses, to polyethylene or hydrogen, of the different target materials were determined from the sigma subbeta values.

  10. ESR-dosimetry in thermal and epithermal neutron fields for application in boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Tobias

    2016-01-22

    Dosimetry is essential for every form of radiotherapy. In Boron Neutron Capture Therapy (BNCT) mixed neutron and gamma fields have to be considered. Dose is deposited in different neutron interactions with elements in the penetrated tissue and by gamma particles, which are always part of a neutron field. The therapeutic dose in BNCT is deposited by densely ionising particles, originating from the fragmentation of the isotope boron-10 after capture of a thermal neutron. Despite being investigated for decades, dosimetry in neutron beams or fields for BNCT remains complex, due to the variety in type and energy of the secondary particles. Today usually ionisation chambers combined with metal foils are used. The applied techniques require extensive effort and are time consuming, while the resulting uncertainties remain high. Consequently, the investigation of more effective techniques or alternative dosimeters is an important field of research. In this work the possibilities of ESR-dosimeters in those fields have been investigated. Certain materials, such as alanine, generate stable radicals upon irradiation. Using Electron Spin Resonance (ESR) spectrometry the amount of radicals, which is proportional to absorbed dose, can be quantified. Different ESR detector materials have been irradiated in the thermal neutron field of the research reactor TRIGA research reactor in Mainz, Germany, with five setups, generating different secondary particle spectra. Further irradiations have been conducted in two epithermal neutron beams. The detector response, however, strongly depends on the dose depositing particle type and energy. It is hence necessary to accompany measurements by computational modelling and simulation. In this work the Monte Carlo code FLUKA was used to calculate absorbed doses and dose components. The relative effectiveness (RE), linking absorbed dose and detector response, has been calculated using amorphous track models. For the simulation, detailed models of

  11. SIXTH ERDA WORKSHOP ON PERSONNEL NEUTRON DOSIMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Vallario, E. J.; Hankins, D. E.; Bramson, P. E.

    1977-07-11

    This workshop was the sixth of a series and was held on July 11 and 12, 1977, at the Oak Ridge National Laboratory in Oak Ridge, Tennessee. Those presenting papers at the Sixth Workshop prepared summary reports of their recent work for inclusion in this document. The reports are reproduced here as submitted by the participants, with only minor editing. This year's Workshop took a decidedly international flavor, with participants from seven countries in addition to the United States. The significance of this group's contributions has raised the possibility that the next Neutron Dosimetry Workshop may be held in Europe. Of particular interest at the Workshop was the keynote address by Dr. Harald Rossi. He commented that there is evidence that 1) accepted values of RBE for low absorbed doses of neutrons may be low by an order of magnitude or more and 2) the risk of leukemia is significant at 0.5 rad to the bone narrow. A reduction of the limit for permissible neutron exposure, which could result from consideration of this information, would necessitate major improvements in our "middle ages" neutron dosimetry. A number of participants reported conversions to thermoluminescent dosimeter (TLD) systems. This move has not been unanimous, however, as there were several reports of apparently satisfactory fission fragment, activation foil, and NTA film dosimeters. While thementionof NTA film resulted in the usual discussion of energy cut off and humidity effects, it seems the use of NTA in accelerator environments still has some merit. Discussion of fission fragment dosimeters centered around track etching techniques, which have shown some improvement. Of particular interest was Tommasino's report on the use of polycarbonate centrifuge tubes as the sensitive element. Thermally stimulated exoelectron emission (TSEE), never very popular for personnel dosimetry, has lost additional ground with the report that the neutron/gamma response ratio is much less than

  12. Materials for Low-Energy Neutron Radiation Shielding

    Science.gov (United States)

    Singleterry, Robert C., Jr.; Thibeault, Sheila A.

    2000-01-01

    Various candidate aircraft and spacecraft materials were analyzed and compared in a low-energy neutron environment using the Monte Carlo N-Particle (MCNP) transport code with an energy range up to 20 MeV. Some candidate materials have been tested in particle beams, and others seemed reasonable to analyze in this manner before deciding to test them. The two metal alloys analyzed are actual materials being designed into or used in aircraft and spacecraft today. This analysis shows that hydrogen-bearing materials have the best shielding characteristics over the metal alloys. It also shows that neutrons above 1 MeV are reflected out of the face of the slab better by larger quantities of carbon in the material. If a low-energy absorber is added to the material, fewer neutrons are transmitted through the material. Future analyses should focus on combinations of scatterers and absorbers to optimize these reaction channels and on the higher energy neutron component (above 50 MeV).

  13. Neutron Transport and Nuclear Burnup Analysis for the Laser Inertial Confinement Fusion-Fission Energy (LIFE) Engine

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, K J; Latkowski, J F; Abbott, R P; Boyd, J K; Powers, J J; Seifried, J E

    2008-10-24

    Lawrence Livermore National Laboratory is currently developing a hybrid fusion-fission nuclear energy system, called LIFE, to generate power and burn nuclear waste. We utilize inertial confinement fusion to drive a subcritical fission blanket surrounding the fusion chamber. It is composed of TRISO-based fuel cooled by the molten salt flibe. Low-yield (37.5 MJ) targets and a repetition rate of 13.3 Hz produce a 500 MW fusion source that is coupled to the subcritical blanket, which provides an additional gain of 4-8, depending on the fuel. In the present work, we describe the neutron transport and nuclear burnup analysis. We utilize standard analysis tools including, the Monte Carlo N-Particle (MCNP) transport code, ORIGEN2 and Monteburns to perform the nuclear design. These analyses focus primarily on a fuel composed of depleted uranium not requiring chemical reprocessing or enrichment. However, other fuels such as weapons grade plutonium and highly-enriched uranium are also under consideration. In addition, we have developed a methodology using {sup 6}Li as a burnable poison to replace the tritium burned in the fusion targets and to maintain constant power over the lifetime of the engine. The results from depleted uranium analyses suggest up to 99% burnup of actinides is attainable while maintaining full power at 2GW for more than five decades.

  14. Practical absorption limits of MPP absorber

    Institute of Scientific and Technical Information of China (English)

    MAA Dah-You

    2006-01-01

    The construction and properties of microperforated panel (MPP) absorber are discussed. The absorption limit of the absorber had been shown that low values of the perforate constant k = d(f/10)1/2 and the orifice diameter d (in mm) are essential for MPP to have high absorption in wide frequency band. To find the exact limits, take 1 for k as a start, because both specific resistance and high absorption require k around one. And the orifice diameter d is chosen as 0.1 mm, so that the peak absorption coefficient (resonance absorption) is at 1000 Hz,and high sound frequency may be in the absorption region. Is it possible for a single layer of such an MPP to cover the whole absorption region required in practice? The half-absorption limit is not a good criterion, because low absorption comes in also in some cases. The 0.5 absorption coefficient limit is suggested for practical region, as a standard for comparison. Absorption curves were drawn for different load resistances, of absorption coefficients versus frequency.Ordinary MPP absorber absorbs in slightly over two octaves, and the new absorber with r = 1 (specific resistance equal to the characteristic impedance in air)is slightly better than these, 2.5 octaves. The new absorbers with r > 1, are much better than these, and some satisfies high absorption in broad frequency range. Realization of these will mean great progress of MPP absorbers.

  15. Neutron scattering in liquids

    Energy Technology Data Exchange (ETDEWEB)

    Barocchi, F. [Florence Univ. (Italy). Ist. di Fisica

    1996-12-31

    Together with X-rays, thermal neutrons are the ideal probe to study the microscopic structure of condensed matter, however the precision attainable usually with neutrons for the measurement of atomic position correlation functions in liquids is, at least, one order of magnitude better than for X-rays. In order to measure properly the microscopic dynamics a wide range of momentum transfer with corresponding energy transfer must be available in the range of liquid state excitations. This again is only attainable, with good resolution, with neutrons. (author) 7 figs., 3 refs.

  16. Neutrons in soft matter

    CERN Document Server

    Imae, Toyoko; Furusaka, Michihiro; Torikai, Naoya

    2011-01-01

    Neutron and synchrotron facilities, which are beyond the scale of the laboratory, and supported on a national level in countries throughout the world.  These tools for probing micro- and nano-structure research and on fast dynamics research of atomic location in materials have been key in the development of new polymer-based materials. Different from several existing professional books on neutron science, this book focuses on theory, instrumentation, an applications. The book is divided into five parts: Part 1 describes the underlying theory of neutron scattering. Part 2 desc

  17. Estimation of the neutron field around the HERA proton beam dump

    Science.gov (United States)

    Möhring, H.-J.; Noack, K.; Zazula, J. M.

    1991-01-01

    In this article we present estimates for the neutron fluences above 0.1 MeV to be expected around the proton beam dump of the HERA machine at DESY at 1000 GeV incident energy. The most important details of the absorber and tunnel layout are approximately modeled using the Cartesian and combinatorial geometry packages. In our method a volume neutron source for MORSE Monte Carlo neutron transport calculations has been determined from star densities obtained from the FLUKA Monte Carlo hadronic shower code, combined with estimates of low-energy neutron yields based on results of intranuclear cascade calculations and of the statistical model of evaporation. The calculated neutron fluences are in reasonable agreement with results obtained by the FLUNEV version of the FLUKA code, currently developed at DESY, as well as with estimates based on empirically determined conversion factors between star density and neutron fluence. Additionally, we present neutron spectra and the corresponding dose equivalents as well as the absorbed doses in beam dump materials obtained from the FLUNEV code.

  18. Compositional variability across Mercury's surface revealed by MESSENGER measurements of variations in thermal neutron count rates

    Science.gov (United States)

    Peplowski, P. N.; Lawrence, D. J.; Goldsten, J. O.; Nittler, L. R.; Solomon, S. C.

    2013-12-01

    Measurements by MESSENGER's Gamma-Ray and Neutron Spectrometer (GRNS) have revealed variations in the flux of thermal neutrons across Mercury's northern hemisphere. These variations are interpreted to originate from spatial variations in surface elemental composition. In particular, the measurements are sensitive to the near-surface abundances of elements that absorb thermal neutrons, including major rock-forming elements such as Fe and Ti, minor elements such as Mn and Cl, and rare-earth elements such as Gd and Sm. We have constructed a map of thermal neutron variability across the surface and compared it with known variations in elemental composition and with the distribution of geologic units. Development of the map included the derivation of the macroscopic thermal neutron absorption cross section across the surface, a quantity whose value and variability provides useful constraints on the formation and geochemical evolution of Mercury's crust. Finally, by combining the thermal neutron measurements with previously reported elemental measurements from the GRNS and MESSENGER's X-Ray Spectrometer, we have derived constraints on the abundances of neutron-absorbing elements, including previously unreported limits for some minor and rare-earth elements.

  19. High-speed neutron radiography for monitoring the water absorption by capillarity in porous materials

    Science.gov (United States)

    Cnudde, Veerle; Dierick, Manuel; Vlassenbroeck, Jelle; Masschaele, Bert; Lehmann, Eberhard; Jacobs, Patric; Van Hoorebeke, Luc

    2008-01-01

    Fluid flow through porous natural building stones is of great importance when studying their weathering processes. Many traditional experiments based on mass changes are available for studying liquid transport in porous stones, such as the determination of the water absorption coefficient by capillarity. Because thermal neutrons experience a strong attenuation by hydrogen, neutron radiography is a suitable technique for the study of water absorption by capillarity in porous stones. However, image contrast can be impaired because hydrogen mainly scatters neutrons rather than absorbing them, resulting in a blurred image. Capillarity results obtained by neutron radiography and by the European Standard 1925 for the determination of the water absorption coefficient by capillarity for natural building stones with a variable porosity were compared. It is illustrated that high-speed neutron radiography can be a useful research tool for the visualization of internal fluid flow inside inorganic building materials such as limestones and sandstones.

  20. Resonance capture gamma-ray spectrometry at Lead Slowing-down Neutron Spectrometer

    CERN Document Server

    Pourimani, R; Popov, Y P; Przytula, M; Wojtkiewicz, R

    2002-01-01

    A new method of measurement of the gamma-ray spectra from resonance neutron capture that can be realized at Lead Slowing-down Neutron Spectrometers was proposed and tested experimentally. The specific feature of the method is the shielding of germanium detector by a 'thick' investigated sample that absorbs intensive neutron flux with energies corresponding to sample resonances. In these energy regions the detector response on neutron irradiation is considerably reduced while the sample gamma-ray spectra are greatly strengthened. The detector response gamma-ray spectra are presented and analysed, and the spectra from neutron capture in tantalum resonances at energies 4.28 and 10.36 eV are shown. The obtained results demonstrate the usefulness of the proposed method. Five new excited levels in germanium isotopes are proposed.

  1. Development of a dual phantom technique for measuring the fast neutron component of dose in boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Sakurai, Yoshinori, E-mail: yosakura@rri.kyoto-u.ac.jp; Tanaka, Hiroki; Kondo, Natsuko; Kinashi, Yuko; Suzuki, Minoru; Masunaga, Shinichiro; Ono, Koji; Maruhashi, Akira [Kyoto University Research Reactor Institute, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

    2015-11-15

    Purpose: Research and development of various accelerator-based irradiation systems for boron neutron capture therapy (BNCT) is underway throughout the world. Many of these systems are nearing or have started clinical trials. Before the start of treatment with BNCT, the relative biological effectiveness (RBE) for the fast neutrons (over 10 keV) incident to the irradiation field must be estimated. Measurements of RBE are typically performed by biological experiments with a phantom. Although the dose deposition due to secondary gamma rays is dominant, the relative contributions of thermal neutrons (below 0.5 eV) and fast neutrons are virtually equivalent under typical irradiation conditions in a water and/or acrylic phantom. Uniform contributions to the dose deposited from thermal and fast neutrons are based in part on relatively inaccurate dose information for fast neutrons. This study sought to improve the accuracy in the dose estimation for fast neutrons by using two phantoms made of different materials in which the dose components can be separated according to differences in the interaction cross sections. The development of a “dual phantom technique” for measuring the fast neutron component of dose is reported. Methods: One phantom was filled with pure water. The other phantom was filled with a water solution of lithium hydroxide (LiOH) capitalizing on the absorbing characteristics of lithium-6 (Li-6) for thermal neutrons. Monte Carlo simulations were used to determine the ideal mixing ratio of Li-6 in LiOH solution. Changes in the depth dose distributions for each respective dose component along the central beam axis were used to assess the LiOH concentration at the 0, 0.001, 0.01, 0.1, 1, and 10 wt. % levels. Simulations were also performed with the phantom filled with 10 wt. % {sup 6}LiOH solution for 95%-enriched Li-6. A phantom was constructed containing 10 wt. % {sup 6}LiOH solution based on the simulation results. Experimental characterization of the

  2. Graphene and Graphene Metamaterials for Terahertz Absorbers

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Pizzocchero, Filippo; Booth, Tim

    2013-01-01

    Graphene, due to the possibility to tune its conductivity, is the promising material for a range of the terahertz (THz) applications, such as tunable reflectors, absorbers, modulators, filters and polarization converters. Subwavelength structuring of graphene in order to form metamaterials allows...... for even more control over the THz waves. In this poster presentation I will show an elegant way to describe the graphene metamaterials and the design of graphene based absorbers. I will also present our recent experimental results on the graphene absorbers characterization....

  3. The nonlinear piezoelectric tuned vibration absorber

    Science.gov (United States)

    Soltani, P.; Kerschen, G.

    2015-07-01

    This paper proposes a piezoelectric vibration absorber, termed the nonlinear piezoelectric tuned vibration absorber (NPTVA), for the mitigation of nonlinear resonances of mechanical systems. The new feature of the NPTVA is that its nonlinear restoring force is designed according to a principle of similarity, i.e., the NPTVA should be an electrical analog of the nonlinear host system. Analytical formulas for the NPTVA parameters are derived using the homotopy perturbation method. Doing so, a nonlinear generalization of Den Hartog’s equal-peak tuning rule is developed for piezoelectric vibration absorbers.

  4. Design and application of functional absorbers

    Institute of Scientific and Technical Information of China (English)

    WANG Jiqing

    2004-01-01

    This paper gives an overview of the research at Institute of Acoustics, Tongji University, on functional absorbers and experience acquired in practical applications over the past three decades. Experiments and analysis of the absorption characteristics of three different geometrical forms of functional absorbers, i.e., panels, cubes and tubes, were conducted with different arrangements. The resulting esthetical effects are illustrated with pictures. Several non-fiber materials are used to compose functional absorbers with advantages both in acoustic properties and in architectural features. Cost effectiveness analysis is also given in order to provide design guidelines.

  5. Absorbed Energy in Ship Collisions and Grounding

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Zhang, Shengming

    1998-01-01

    is that the absorbed energy does not depend on the arrangement of the structure, the material properties, and the damage mode.The purpose of the present paper is to establish a new simple relation between the absorbed energy and the destroyed material volume, which can be used as a design tool for analysis of ship......Minorsky's well-known empirical formula, which relates the absorbed energy to the destroyed material volume, has been widely used in analyses of high energy collision and grounding accidents for nearly 40 years. The advantage of the method is its apparent simplcity. Obviously, its drawback...

  6. HERSCHEL AND SPITZER OBSERVATIONS OF SLOWLY ROTATING, NEARBY ISOLATED NEUTRON STARS

    Energy Technology Data Exchange (ETDEWEB)

    Posselt, B.; Pavlov, G. G. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Popov, S. [Sternberg Astronomical Institute, Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Wachter, S., E-mail: posselt@psu.edu [Max Planck Institute for Astronomy, Königsstuhl 17, D-69117 Heidelberg (Germany)

    2014-11-01

    Supernova fallback disks around neutron stars have been suspected to influence the evolution of the diverse neutron star populations. Slowly rotating neutron stars are the most promising places to find such disks. Searching for the cold and warm debris of old fallback disks, we carried out Herschel PACS (70 μm, 160 mu m) and Spitzer IRAC (3.6 μm, 4.5 μm) observations of eight slowly rotating (P ≈ 3-11 s) nearby (<1 kpc) isolated neutron stars. Herschel detected 160 μm emission (>5σ) at locations consistent with the positions of the neutron stars RX J0806.4-4123 and RX J2143.0+0654. No other significant infrared emission was detected from the eight neutron stars. We estimate probabilities of 63%, 33%, and 3% that, respectively, none, one, or both Herschel PACS 160 μm detections are unrelated excess sources due to background source confusion or an interstellar cirrus. If the 160 μm emission is indeed related to cold (10-22 K) dust around the neutron stars, this dust is absorbing and re-emitting ∼10% to ∼20% of the neutron stars' X-rays. Such high efficiencies would be at least three orders of magnitude larger than the efficiencies of debris disks around nondegenerate stars. While thin dusty disks around the neutron stars can be excluded as counterparts of the 160 μm emission, dusty asteroid belts constitute a viable option.

  7. A comparative study of the attenuation of reactor thermal neutrons in different types of concrete

    Energy Technology Data Exchange (ETDEWEB)

    Bashiter, I.I. [Zagazig Univ. (Egypt). Dept. of Physics; El-Sayed Abdo, A.; Makarious, A.S. [Atomic Energy Authority, Cairo (Egypt). Nuclear Research Centre

    1996-05-20

    This study was carried out to assess the distribution of thermal neutrons emitted directly from the core of the ET-RR-1 reactor in ordinary concrete, ilmenite concrete and ilmenite-limonite concrete shields. Measurements were carried out by using a direct beam and a cadmium filtered beam of reactor neutrons. The neutron dose distributions were measured using Li{sub 2}B{sub 4}O{sub 7}:Mn thermoluminescent dosimeters. The data obtained show that ilmenite concrete is better for slow and thermal neutron attenuation than both ordinary and ilmenite-limonite concrete. Also it was concluded that thermal neutrons emitted directly from the reactor core are highly absorbed within the first few centimeters of each type of concrete. The thickness of ilmenite concrete required to attenuate the doses of neutrons to a certain value along the beam axis for a direct reactor beam estimated to be about 75 and 57% of the shield thickness made from ordinary and ilmenite-limonite concretes, respectively. Empirical formulae were derived to calculate the neutron dose distribution in ordinary, ilmenite and ilmenite-limonite concrete shields both along and perpendicular to the beam axis for both the direct reactor neutrons and the reactor thermal neutrons. (author).

  8. Neutron signal transfer analysis

    CERN Document Server

    Pleinert, H; Lehmann, E

    1999-01-01

    A new method called neutron signal transfer analysis has been developed for quantitative determination of hydrogenous distributions from neutron radiographic measurements. The technique is based on a model which describes the detector signal obtained in the measurement as a result of the action of three different mechanisms expressed by signal transfer functions. The explicit forms of the signal transfer functions are determined by Monte Carlo computer simulations and contain only the distribution as a variable. Therefore an unknown distribution can be determined from the detector signal by recursive iteration. This technique provides a simple and efficient tool for analysis of this type while also taking into account complex effects due to the energy dependency of neutron interaction and single and multiple scattering. Therefore this method provides an efficient tool for precise quantitative analysis using neutron radiography, as for example quantitative determination of moisture distributions in porous buil...

  9. Temperature of neutron stars

    Science.gov (United States)

    Tsuruta, Sachiko

    2016-07-01

    We start with a brief introduction to the historical background in the early pioneering days when the first neutron star thermal evolution calculations predicted the presence of neutron stars hot enough to be observable. We then report on the first detection of neutron star temperatures by ROSAT X-ray satellite, which vindicated the earlier prediction of hot neutron stars. We proceed to present subsequent developments, both in theory and observation, up to today. We then discuss the current status and the future prospect, which will offer useful insight to the understanding of basic properties of ultra-high density matter beyond the nuclear density, such as the possible presence of such exotic particles as pion condensates.

  10. Decoherence Free Neutron Interferometry

    CERN Document Server

    Pushin, Dmitry A; Cory, David G

    2016-01-01

    Perfect single-crystal neutron interferometers are adversely sensitive to environmental disturbances, particularly mechanical vibrations. The sensitivity to vibrations results from the slow velocity of thermal neutrons and the long measurement time that are encountered in a typical experiment. Consequently, to achieve a good interference solutions for reducing vibration other than those normally used in optical experiments must be explored. Here we introduce a geometry for a neutron interferometer that is less sensitive to low-frequency vibrations. This design may be compared with both dynamical decoupling methods and decoherence-free subspaces that are described in quantum information processing. By removing the need for bulky vibration isolation setups, this design will make it easier to adopt neutron interferometry to a wide range of applications and increase its sensitivity.

  11. Neutron Stars Recent Developments

    CERN Document Server

    Heiselberg, H

    1999-01-01

    Recent developments in neutron star theory and observation are discussed. Based on modern nucleon-nucleon potentials more reliable equations of state for dense nuclear matter have been constructed. Furthermore, phase transitions such as pion, kaon and hyperon condensation, superfluidity and quark matter can occur in cores of neutron stars. Specifically, the nuclear to quark matter phase transition and its mixed phases with intriguing structures is treated. Rotating neutron stars with and without phase transitions are discussed and compared to observed masses, radii and glitches. The observations of possible heavy $\\sim 2M_\\odot$ neutron stars in X-ray binaries and QPO's require relatively stiff equation of states and restrict strong phase transitions to occur at very high nuclear densities only.

  12. The intense neutron generator

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, W.B

    1966-07-01

    The presentation discusses both the economic and research contexts that would be served by producing neutrons in gram quantities at high intensities by electrical means without uranium-235. The revenue from producing radioisotopes is attractive. The array of techniques introduced by the multipurpose 65 megawatt Intense Neutron Generator project includes liquid metal cooling, superconducting magnets for beam bending and focussing, super-conductors for low-loss high-power radiofrequency systems, efficient devices for producing radiofrequency power, plasma physics developments for producing and accelerating hydrogen, ions at high intensity that are still far out from established practice, a multimegawatt high voltage D.C. generating machine that could have several applications. The research fields served relate principally to materials science through neutron-phonon and other quantum interactions as well as through neutron diffraction. Nuclear physics is served through {mu}-, {pi}- and K-meson production. Isotope production enters many fields of applied research. (author)

  13. Introduction to neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, W.E. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1996-11-01

    We give here an introduction to the theoretical principles of neutron scattering. The relationship between scattering- and correlation-functions is particularly emphasized. Within the framework of linear response theory (justified by the weakness of the basic interaction) the relation between fluctuation and dissipation is discussed. This general framework explains the particular power of neutron scattering as an experimental method. (author) 4 figs., 4 refs.

  14. Neutron scattering in dimers

    DEFF Research Database (Denmark)

    Gudel, H. U.; Furrer, A.; Kjems, Jørgen

    1986-01-01

    Insulating compounds containing dimers of transition metal and rare earth ions have been studied by inelastic neutron scattering (INS). Energy splittings can be directly determined, and the corresponding parameters are easily extracted from the experimental data. The intensities of dimer excitati......Insulating compounds containing dimers of transition metal and rare earth ions have been studied by inelastic neutron scattering (INS). Energy splittings can be directly determined, and the corresponding parameters are easily extracted from the experimental data. The intensities of dimer...

  15. Pulsed spallation Neutron Sources

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, J.M. [Argonne National Lab., IL (United States)

    1994-12-31

    This paper reviews the early history of pulsed spallation neutron source development at Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provides a few examples of applications in fundamental condensed matter physics, materials science and technology.

  16. In-Pile Experiment of a New Hafnium Aluminide Composite Material to Enable Fast Neutron Testing in the Advanced Test Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Donna Post Guillen; Douglas L. Porter; James R. Parry; Heng Ban

    2010-06-01

    A new hafnium aluminide composite material is being developed as a key component in a Boosted Fast Flux Loop (BFFL) system designed to provide fast neutron flux test capability in the Advanced Test Reactor. An absorber block comprised of hafnium aluminide (Al3Hf) particles (~23% by volume) dispersed in an aluminum matrix can absorb thermal neutrons and transfer heat from the experiment to pressurized water cooling channels. However, the thermophysical properties, such as thermal conductivity, of this material and the effect of irradiation are not known. This paper describes the design of an in-pile experiment to obtain such data to enable design and optimization of the BFFL neutron filter.

  17. Space Compatible Radar Absorbing Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase 1 project shall investigate novel radar absorbing materials (RAM) for use in space or simulated space environments. These materials are lightweight...

  18. An ultra-broadband multilayered graphene absorber

    KAUST Repository

    Amin, Muhammad

    2013-01-01

    An ultra-broadband multilayered graphene absorber operating at terahertz (THz) frequencies is proposed. The absorber design makes use of three mechanisms: (i) The graphene layers are asymmetrically patterned to support higher order surface plasmon modes that destructively interfere with the dipolar mode and generate electromagnetically induced absorption. (ii) The patterned graphene layers biased at different gate voltages backedup with dielectric substrates are stacked on top of each other. The resulting absorber is polarization dependent but has an ultra-broadband of operation. (iii) Graphene\\'s damping factor is increased by lowering its electron mobility to 1000cm 2=Vs. Indeed, numerical experiments demonstrate that with only three layers, bandwidth of 90% absorption can be extended upto 7THz, which is drastically larger than only few THz of bandwidth that can be achieved with existing metallic/graphene absorbers. © 2013 Optical Society of America.

  19. Semiconductor saturable absorbers for ultrafast THz signals

    DEFF Research Database (Denmark)

    Hoffmann, Matthias C.; Turchinovich, Dmitry

    We demonstrate saturable absorber behavior of n-type semiconductors in the THz frequency range using nonlinear THz spectroscopy. Further, we observe THz pulse shortening and increase of the group refractive index at high field strengths....

  20. Neutron scattering in Australia

    Energy Technology Data Exchange (ETDEWEB)

    Knott, R.B. [Australian Nuclear Science and Technology Organisation, Menai (Australia)

    1994-12-31

    Neutron scattering techniques have been part of the Australian scientific research community for the past three decades. The High Flux Australian Reactor (HIFAR) is a multi-use facility of modest performance that provides the only neutron source in the country suitable for neutron scattering. The limitations of HIFAR have been recognized and recently a Government initiated inquiry sought to evaluate the future needs of a neutron source. In essence, the inquiry suggested that a delay of several years would enable a number of key issues to be resolved, and therefore a more appropriate decision made. In the meantime, use of the present source is being optimized, and where necessary research is being undertaken at major overseas neutron facilities either on a formal or informal basis. Australia has, at present, a formal agreement with the Rutherford Appleton Laboratory (UK) for access to the spallation source ISIS. Various aspects of neutron scattering have been implemented on HIFAR, including investigations of the structure of biological relevant molecules. One aspect of these investigations will be presented. Preliminary results from a study of the interaction of the immunosuppressant drug, cyclosporin-A, with reconstituted membranes suggest that the hydrophobic drug interdigitated with lipid chains.

  1. Coded source neutron imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bingham, Philip R [ORNL; Santos-Villalobos, Hector J [ORNL

    2011-01-01

    Coded aperture techniques have been applied to neutron radiography to address limitations in neutron flux and resolution of neutron detectors in a system labeled coded source imaging (CSI). By coding the neutron source, a magnified imaging system is designed with small spot size aperture holes (10 and 100 m) for improved resolution beyond the detector limits and with many holes in the aperture (50% open) to account for flux losses due to the small pinhole size. An introduction to neutron radiography and coded aperture imaging is presented. A system design is developed for a CSI system with a development of equations for limitations on the system based on the coded image requirements and the neutron source characteristics of size and divergence. Simulation has been applied to the design using McStas to provide qualitative measures of performance with simulations of pinhole array objects followed by a quantitative measure through simulation of a tilted edge and calculation of the modulation transfer function (MTF) from the line spread function. MTF results for both 100um and 10um aperture hole diameters show resolutions matching the hole diameters.

  2. Coded source neutron imaging

    Science.gov (United States)

    Bingham, Philip; Santos-Villalobos, Hector; Tobin, Ken

    2011-03-01

    Coded aperture techniques have been applied to neutron radiography to address limitations in neutron flux and resolution of neutron detectors in a system labeled coded source imaging (CSI). By coding the neutron source, a magnified imaging system is designed with small spot size aperture holes (10 and 100μm) for improved resolution beyond the detector limits and with many holes in the aperture (50% open) to account for flux losses due to the small pinhole size. An introduction to neutron radiography and coded aperture imaging is presented. A system design is developed for a CSI system with a development of equations for limitations on the system based on the coded image requirements and the neutron source characteristics of size and divergence. Simulation has been applied to the design using McStas to provide qualitative measures of performance with simulations of pinhole array objects followed by a quantitative measure through simulation of a tilted edge and calculation of the modulation transfer function (MTF) from the line spread function. MTF results for both 100μm and 10μm aperture hole diameters show resolutions matching the hole diameters.

  3. Neutron Nucleic Acid Crystallography.

    Science.gov (United States)

    Chatake, Toshiyuki

    2016-01-01

    The hydration shells surrounding nucleic acids and hydrogen-bonding networks involving water molecules and nucleic acids are essential interactions for the structural stability and function of nucleic acids. Water molecules in the hydration shells influence various conformations of DNA and RNA by specific hydrogen-bonding networks, which often contribute to the chemical reactivity and molecular recognition of nucleic acids. However, X-ray crystallography could not provide a complete description of structural information with respect to hydrogen bonds. Indeed, X-ray crystallography is a powerful tool for determining the locations of water molecules, i.e., the location of the oxygen atom of H2O; however, it is very difficult to determine the orientation of the water molecules, i.e., the orientation of the two hydrogen atoms of H2O, because X-ray scattering from the hydrogen atom is very small.Neutron crystallography is a specialized tool for determining the positions of hydrogen atoms. Neutrons are not diffracted by electrons, but are diffracted by atomic nuclei; accordingly, neutron scattering lengths of hydrogen and its isotopes are comparable to those of non-hydrogen atoms. Therefore, neutron crystallography can determine both of the locations and orientations of water molecules. This chapter describes the current status of neutron nucleic acid crystallographic research as well as the basic principles of neutron diffraction experiments performed on nucleic acid crystals: materials, crystallization, diffraction experiments, and structure determination.

  4. Taming electromagnetic metamaterials for isotropic perfect absorbers

    Directory of Open Access Journals (Sweden)

    Doan Tung Anh

    2015-07-01

    Full Text Available Conventional metamaterial absorbers, which consist of a dielectric spacer sandwiched between metamaterial resonators and a metallic ground plane, have been inherently anisotropic. In this paper, we present an alternative approach for isotropic perfect absorbers using symmetric metamaterial structures. We show that by systematically manipulating the electrically and magnetically induced losses, one can achieve a desired absorption without breaking the structural homogeneity. Finite integration simulations and standard retrieval method are performed to elaborate on our idea.

  5. Absorbing Boundary Conditions for Hyperbolic Systems

    Institute of Scientific and Technical Information of China (English)

    Matthias Ehrhardt

    2010-01-01

    This paper deals with absorbing boundary conditions for hyperbolic systems in one and two space dimensions. We prove the strict well-posedness of the resulting initial boundary value problem in 1D. Afterwards we establish the GKS-stability of the corresponding Lax-Wendroff-type finite difference scheme. Hereby, we have to extend the classical proofs, since the (discretized) absorbing boundary conditions do not fit the standard form of boundary conditions for hyperbolic systems.

  6. Graphene and Graphene Metamaterials for Terahertz Absorbers

    OpenAIRE

    Andryieuski, Andrei; Pizzocchero, Filippo; Booth, Tim; Bøggild, Peter

    2013-01-01

    Graphene, due to the possibility to tune its conductivity, is the promising material for a range of the terahertz (THz) applications, such as tunable reflectors, absorbers, modulators, filters and polarization converters. Subwavelength structuring of graphene in order to form metamaterials allows for even more control over the THz waves. In this poster presentation I will show an elegant way to describe the graphene metamaterials and the design of graphene based absorbers. I will also present...

  7. MAGNETIC NEUTRON SCATTERING

    Energy Technology Data Exchange (ETDEWEB)

    ZALIZNYAK,I.A.; LEE,S.H.

    2004-07-30

    Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern

  8. MAGNETIC NEUTRON SCATTERING

    Energy Technology Data Exchange (ETDEWEB)

    ZALIZNYAK,I.A.; LEE,S.H.

    2004-07-30

    Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern

  9. Perfect terahertz absorber using fishnet based metafilm

    Energy Technology Data Exchange (ETDEWEB)

    Azad, Abul Kalam [Los Alamos National Laboratory; Shchegolkov, Dmitry Yu [Los Alamos National Laboratory; Chen, Houtong [Los Alamos National Laboratory; Taylor, Antoinette [Los Alamos National Laboratory; Smirnova, E I [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory

    2009-01-01

    We present a perfect terahertz (THz) absorber working for a broad-angle of incidence. The two fold symmetry of rectangular fishnet structure allows either complete absorption or mirror like reflection depending on the polarization of incident the THz beam. Metamaterials enable the ability to control the electromagnetic wave in a unique fashion by designing the permittivity or permeability of composite materials with desired values. Although the initial idea of metamaterials was to obtain a negative index medium, however, the evolution of metamaterials (MMs) offers a variety of practically applicable devices for controlling electromagnetic wave such as tunable filters, modulators, phase shifters, compact antenna, absorbers, etc. Terahertz regime, a crucial domain of the electromagnetic wave, is suffering from the scarcity of the efficient devices and might take the advantage of metamaterials. Here, we demonstrate design, fabrication, and characterization of a terahertz absorber based on a simple fishnet metallic film separated from a ground mirror plane by a dielectric spacer. Such absorbers are in particular important for bolometric terahertz detectors, high sensitivity imaging, and terahertz anechoic chambers. Recently, split-ring-resonators (SRR) have been employed for metamaterial-based absorbers at microwave and THz frequencies. The experimental demonstration reveals that such absorbers have absorptivity close to unity at resonance frequencies. However, the downside of these designs is that they all employ resonators of rather complicated shape with many fine parts and so they are not easy to fabricate and are sensitive to distortions.

  10. Advances in micro-perforated panel absorbers

    Institute of Scientific and Technical Information of China (English)

    LIU Ke; TIAN Jing; JIAO Fenglei; L(U) Yadong

    2006-01-01

    Theoretical and experimental investigations on the performance of micro-perforated-panel absorbers are reviewed in this paper. By reviewing recent research work, this paper reveals a relationship between the maximum absorption coefficient and the limit of the absorption frequency bandwidth. It has been demonstrated that the absorption frequency bandwidth can be extended up to 3 or 4 octaves as the diameters of the micro-holes decrease. This has become possible with the development of the technologies for manufacturing micro-perforated panels,such as laser drilling, powder metallurgy, welded meshing and electro-etching to form micrometer order holes. In this paper, absorption characteristics of such absorbers in random fields and in high sound intensity are discussed both theoretically and experimentally. A new absorbing structure based on micro-perforated-panel absorbers demonstrate experimentally high sound absorption capability. This review shows that the micro-perforated-panel absorber has potentials to be one of ideal absorbing materials in the 21st century.

  11. Adaptive Piezoelectric Absorber for Active Vibration Control

    Directory of Open Access Journals (Sweden)

    Sven Herold

    2016-02-01

    Full Text Available Passive vibration control solutions are often limited to working reliably at one design point. Especially applied to lightweight structures, which tend to have unwanted vibration, active vibration control approaches can outperform passive solutions. To generate dynamic forces in a narrow frequency band, passive single-degree-of-freedom oscillators are frequently used as vibration absorbers and neutralizers. In order to respond to changes in system properties and/or the frequency of excitation forces, in this work, adaptive vibration compensation by a tunable piezoelectric vibration absorber is investigated. A special design containing piezoelectric stack actuators is used to cover a large tuning range for the natural frequency of the adaptive vibration absorber, while also the utilization as an active dynamic inertial mass actuator for active control concepts is possible, which can help to implement a broadband vibration control system. An analytical model is set up to derive general design rules for the system. An absorber prototype is set up and validated experimentally for both use cases of an adaptive vibration absorber and inertial mass actuator. Finally, the adaptive vibration control system is installed and tested with a basic truss structure in the laboratory, using both the possibility to adjust the properties of the absorber and active control.

  12. Fundamental neutron physics at LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Greene, G.

    1995-10-01

    Modern neutron sources and science share a common origin in mid-20th-century scientific investigations concerned with the study of the fundamental interactions between elementary particles. Since the time of that common origin, neutron science and the study of elementary particles have evolved into quite disparate disciplines. The neutron became recognized as a powerful tool for studying condensed matter with modern neutron sources being primarily used (and justified) as tools for neutron scattering and materials science research. The study of elementary particles has, of course, led to the development of rather different tools and is now dominated by activities performed at extremely high energies. Notwithstanding this trend, the study of fundamental interactions using neutrons has continued and remains a vigorous activity at many contemporary neutron sources. This research, like neutron scattering research, has benefited enormously by the development of modern high-flux neutron facilities. Future sources, particularly high-power spallation sources, offer exciting possibilities for continuing this research.

  13. Investigation of neutron converters for production of optically stimulated luminescence (OSL) neutron dosimeters using Al{sub 2}O{sub 3}:C

    Energy Technology Data Exchange (ETDEWEB)

    Mittani, J.C.R. [Department of Physics, Oklahoma State University, Stillwater, OK 74078-3072 (United States); Silva, A.A.R. da [Department of Physics, Oklahoma State University, Stillwater, OK 74078-3072 (United States); Vanhavere, F. [SCK.CEN, Belgian Nuclear Research Centre, Boeretang 200, 2400 Mol (Belgium); Akselrod, M.S. [Landauer, Inc., Stillwater Crystal Growth Division, 723 1/2 Eastgate Rd., Stillwater, OK 74074 (United States); Yukihara, E.G. [Department of Physics, Oklahoma State University, Stillwater, OK 74078-3072 (United States)]. E-mail: eduardo.yukihara@okstate.edu

    2007-07-15

    This paper presents the optically stimulated luminescence (OSL) properties of neutron dosimeters in powder and in the form of pellets prepared with a mixture of Al{sub 2}O{sub 3}:C and neutron converters. The neutron converters investigated were high density polyethylene (HDPE), lithium fluoride (LiF), lithium fluoride 95% enriched with {sup 6}Li ({sup 6}LiF), lithium carbonate 95% enriched with {sup 6}Li ({sup 6}Li{sub 2}CO{sub 3}), boric acid enriched with 99% of {sup 10}B (H{sub 3}{sup 10}BO{sub 3}) and gadolinium oxide (Gd{sub 2}O{sub 3}). The proportion of Al{sub 2}O{sub 3}:C and neutron converter in the mixture was varied to optimize the total OSL signal and neutron sensitivity. The neutron sensitivity and dose-response were determined for the OSL dosimeters using a bare {sup 252}Cf source and compared to the response of Harshaw TLD-600 and TLD-700 dosimeters ({sup 6}LiF:Mg,Ti and {sup 7}LiF:Mg,Ti). The results demonstrate the possibility of developing an OSL dosimeter made of Al{sub 2}O{sub 3}:C powder and neutron converter with a neutron sensitivity (defined as the ratio between the {sup 60}Co equivalent gamma dose and the reference neutron absorbed dose) and neutron-gamma discrimination comparable to the TLD-600/TLD-700 combination. It was shown that the shape of the OSL decay curves varied with the type of the neutron converter, demonstrating the influence of the energy deposition mechanism and ionization density on the OSL process in Al{sub 2}O{sub 3}:C.

  14. Etude de la diagraphie neutron du granite de Beauvoir. Effet neutron des altérations et de la matrice du granite. Calibration granite. Porosité totale à l'eau et porosité neutron Analysis of the Beauvoir Granite Neutron Log. Neutron Effect of Alterations and of the Granite Matrix. Granite Calibration. Total Water Porosity and Neutron Porosity

    Directory of Open Access Journals (Sweden)

    Galle C.

    2006-11-01

    carottes (n. Nous montrons que, pour le granite de Beauvoir, l'effet neutron de la matrice est important (en moyenne proche de 7% et ne peut être négligé lorsque l'on mesure des porosités voisines de 0,5% sur carottes. La calibration de l'outil neutron dans le granite et non pas dans des calcaires est d'autre part capitale quant à la précision quantitative des résultats. This article describes the research done on the Beauvoir granite (Echassières GPF 1 borehole, French Massif Central range. The aim of this project was to obtain representative values of the water saturation (n total free water porosity of the Beauvoir granite from PorosityN neutron porosity (BRGM neutron log. The exact knowledge of the porosity of a crystalline block is effectively fundamental to determine its possibilities for being used as a waste storage site. With this goal, neutron logging provides indispensable information concerning the characterization of a porous medium. Our procedure was experimental, and we tried to go more deeply into various problems linked to the use of neutron logging in a granitic rock. Two main factors governed the neutron response : (i the hydrogen concentration of the formation (free water and combined water of various minerals and (ii the presence of absorber elements with a large capture cross-section such as gadolinium, cadmium, boron as well as lithium for the Beauvoir granite. After measuring the Beauvoir granite n total (free water porosity on core samples, we evaluated the combined water content of each sample tested on the basis of fire loss tests on rock powder at 900°C. From the hydrogen atoms volumic concentration, we determined a hydrogen index that we directly converted into the PorosityN(OH- neutron porosity, (by definition, pure water at 20°C has a hydrogen index of 1 which is equivalent to a 100% porosity. For the Beauvoir granite, the matrix combined water represents an average neutron porosity (Table 1 of about 4%. In the second phase, we used

  15. Radiography with polarised neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Michael L.

    2010-08-20

    In this thesis I present a new technique for the spatially resolved investigation of the magnetic properties of bulk samples. Standard one dimensional neutron depolarisation analysis is combined with neutron radiography to a method we call Neutron Depolarisation Imaging (NDI). The experimental setup which was installed at the neutron radiography beam line ANTARES at FRM II consists of a double crystal monochromator, neutron polariser, spin flipper, polarisation analyser and a position sensitive CCD detector. A comprehensive discussion of the requirements for these components is given and the limitations of the method are shown. The maximum spatial resolution which can be achieved with a neutron radiography setup is determined by the collimation of the neutron beam and the distance between sample and detector. Different types of polarisers have been tested and their advantages and disadvantages are discussed. A double crystal monochromator and a new type of polariser employing polarising neutron supermirrors based on the principle of an optical periscope were developed and tested during this work. Furthermore, NDI measurements on various samples of the weakly ferromagnetic materials Pd{sub 1-x}Ni{sub x} and Ni{sub 3}Al are presented. Neutron depolarisation radiography and tomography measurements were conducted with a spatial resolution as high as 0.3 mm on Pd{sub 1-x}Ni{sub x} and Ni{sub 3}Al samples. The feasibility of NDI experiments under hydrostatic pressures up to 10 kbar was shown on a sample of Ni{sub 3}Al using a modified Cu:Be clamp cell. A decrease of the ordering temperature by 2 K under hydrostatic pressure was determined from the NDI measurements and shows the potential of the method for further high pressure experiments. Additionally a method was developed which in principle allows to obtain the intrinsic dependence of the ordering temperature T{sub C} on the ordered moment Ms from NDI measurements on inhomogeneous samples containing regions with

  16. Optimization of a bolometer detector for ITER based on Pt absorber on SiN membrane.

    Science.gov (United States)

    Meister, H; Eich, T; Endstrasser, N; Giannone, L; Kannamüller, M; Kling, A; Koll, J; Trautmann, T; Detemple, P; Schmitt, S

    2010-10-01

    Any plasma diagnostic in ITER must be able to operate at temperatures in excess of 200 °C and neutron loads corresponding to 0.1 dpa over its lifetime. To achieve this aim for the bolometer diagnostic, a miniaturized metal resistor bolometer detector based on Pt absorbers galvanically deposited on SiN membranes is being developed. The first two generations of detectors featured up to 4.5 μm thick absorbers. Results from laboratory tests are presented characterizing the dependence of their calibration constants under thermal loads up to 450 °C. Several detectors have been tested in ASDEX Upgrade providing reliable data but also pointing out the need for further optimization. A laser trimming procedure has been implemented to reduce the mismatch in meander resistances below 1% for one detector and the thermal drifts from this mismatch.

  17. Optimization of a bolometer detector for ITER based on Pt absorber on SiN membrane

    Energy Technology Data Exchange (ETDEWEB)

    Meister, H.; Eich, T.; Endstrasser, N.; Giannone, L.; Kannamueller, M.; Kling, A.; Koll, J.; Trautmann, T. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany); Detemple, P.; Schmitt, S. [Institut fuer Mikrotechnik Mainz GmbH, Carl-Zeiss-Str. 18-20, D-55129 Mainz (Germany); Collaboration: ASDEX Upgrade Team

    2010-10-15

    Any plasma diagnostic in ITER must be able to operate at temperatures in excess of 200 deg. C and neutron loads corresponding to 0.1 dpa over its lifetime. To achieve this aim for the bolometer diagnostic, a miniaturized metal resistor bolometer detector based on Pt absorbers galvanically deposited on SiN membranes is being developed. The first two generations of detectors featured up to 4.5 {mu}m thick absorbers. Results from laboratory tests are presented characterizing the dependence of their calibration constants under thermal loads up to 450 deg. C. Several detectors have been tested in ASDEX Upgrade providing reliable data but also pointing out the need for further optimization. A laser trimming procedure has been implemented to reduce the mismatch in meander resistances below 1% for one detector and the thermal drifts from this mismatch.

  18. Neutron-Induced Failures in Semiconductor Devices

    Energy Technology Data Exchange (ETDEWEB)

    Wender, Stephen Arthur [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-04-06

    This slide presentation explores single event effect, environmental neutron flux, system response, the Los Alamos Neutron Science Center (LANSCE) neutron testing facility, examples of SEE measurements, and recent interest in thermal neutrons.

  19. Neutron drip transition in accreting and nonaccreting neutron star crusts

    CERN Document Server

    Chamel, N; Zdunik, J L; Haensel, P

    2015-01-01

    The neutron-drip transition in the dense matter constituting the interior of neutron stars generally refers to the appearance of unbound neutrons as the matter density reaches some threshold density $\\rho_\\textrm{drip}$. This transition has been mainly studied under the cold catalyzed matter hypothesis. However, this assumption is unrealistic for accreting neutron stars. After examining the physical processes that are thought to be allowed in both accreting and nonaccreting neutron stars, suitable conditions for the onset of neutron drip are derived and general analytical expressions for the neutron drip density and pressure are obtained. Moreover, we show that the neutron-drip transition occurs at lower density and pressure than those predicted within the mean-nucleus approximation. This transition is studied numerically for various initial composition of the ashes from X-ray bursts and superbursts using microscopic nuclear mass models.

  20. Design of a single moderator-type neutron spectrometer with enhanced energy resolution in the energy range from a few to 100 keV

    Energy Technology Data Exchange (ETDEWEB)

    Tanimura, Y. [Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)]. E-mail: tanimura@popsvr.tokai.jaeri.go.jp; Saegusa, J. [Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Yoshizawa, M. [Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Yoshida, M. [Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)

    2005-08-01

    The moderator structure for a neutron spectrometer was optimized with the Monte Carlo code MCNP-4B. The spectrometer consists of a cylindrical moderator and a position-sensitive thermal neutron detector and obtains energy spectra from thermal neutron distribution along its cylindrical axis. The structure of the moderator was improved by using a low hydrogen density material on one end and a high hydrogen density on the other, and inserting a neutron absorber that eliminates thermal neutron diffusion. This design improves the energy resolution of the spectrometer, especially for low-energy neutrons from a few to 100 keV. The designed spectrometer can be applied to the measurement of energy spectra over a neutron energy range from a few keV to 20 MeV.

  1. Space radiation absorbed dose distribution in a human phantom

    Science.gov (United States)

    Badhwar, G. D.; Atwell, W.; Badavi, F. F.; Yang, T. C.; Cleghorn, T. F.

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

  2. Hybrid superconducting neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Merlo, V.; Lucci, M.; Ottaviani, I. [Dipartimento di Fisica, Università Tor Vergata, Via della Ricerca Scientifica, I-00133 Roma (Italy); Salvato, M.; Cirillo, M. [Dipartimento di Fisica, Università Tor Vergata, Via della Ricerca Scientifica, I-00133 Roma (Italy); CNR SPIN Salerno, Università di Salerno, Via Giovanni Paolo II, n.132, 84084 Fisciano (Italy); Scherillo, A. [Science and Technology Facility Council, ISIS Facility Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Celentano, G. [ENEA Frascati Research Centre, Via. E. Fermi 45, 00044 Frascati (Italy); Pietropaolo, A., E-mail: antonino.pietropaolo@enea.it [ENEA Frascati Research Centre, Via. E. Fermi 45, 00044 Frascati (Italy); Mediterranean Institute of Fundamental Physics, Via Appia Nuova 31, 00040 Marino, Roma (Italy)

    2015-03-16

    A neutron detection concept is presented that is based on superconductive niobium (Nb) strips coated by a boron (B) layer. The working principle of the detector relies on the nuclear reaction, {sup 10}B + n → α + {sup 7}Li, with α and Li ions generating a hot spot on the current-biased Nb strip which in turn induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection principle has been experimentally assessed and verified by irradiating the samples with a pulsed neutron beam at the ISIS spallation neutron source (UK). It is found that the boron coated superconducting strips, kept at a temperature T = 8 K and current-biased below the critical current I{sub c}, are driven into the normal state upon thermal neutron irradiation. As a result of the transition, voltage pulses in excess of 40 mV are measured while the bias current can be properly modulated to bring the strip back to the superconducting state, thus resetting the detector. Measurements on the counting rate of the device are presented and the basic physical features of the detector are discussed.

  3. Hybrid Superconducting Neutron Detectors

    CERN Document Server

    Merlo, V; Cirillo, M; Lucci, M; Ottaviani, I; Scherillo, A; Celentano, G; Pietropaolo, A

    2014-01-01

    A new neutron detection concept is presented that is based on superconductive niobium (Nb) strips coated by a boron (B) layer. The working principle of the detector relies on the nuclear reaction 10B+n $\\rightarrow$ $\\alpha$+ 7Li , with $\\alpha$ and Li ions generating a hot spot on the current-biased Nb strip which in turn induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection principle has been experimentally assessed and verified by irradiating the samples with a pulsed neutron beam at the ISIS spallation neutron source (UK). It is found that the boron coated superconducting strips, kept at a temperature T = 8 K and current-biased below the critical current Ic, are driven into the normal state upon thermal neutron irradiation. As a result of the transition, voltage pulses in excess of 40 mV are measured while the bias current can be properly modulated to bring the strip back to the supercond...

  4. Neutron counting with cameras

    Energy Technology Data Exchange (ETDEWEB)

    Van Esch, Patrick; Crisanti, Marta; Mutti, Paolo [Institut Laue Langevin, Grenoble (France)

    2015-07-01

    A research project is presented in which we aim at counting individual neutrons with CCD-like cameras. We explore theoretically a technique that allows us to use imaging detectors as counting detectors at lower counting rates, and transits smoothly to continuous imaging at higher counting rates. As such, the hope is to combine the good background rejection properties of standard neutron counting detectors with the absence of dead time of integrating neutron imaging cameras as well as their very good spatial resolution. Compared to Xray detection, the essence of thermal neutron detection is the nuclear conversion reaction. The released energies involved are of the order of a few MeV, while X-ray detection releases energies of the order of the photon energy, which is in the 10 KeV range. Thanks to advances in camera technology which have resulted in increased quantum efficiency, lower noise, as well as increased frame rate up to 100 fps for CMOS-type cameras, this more than 100-fold higher available detection energy implies that the individual neutron detection light signal can be significantly above the noise level, as such allowing for discrimination and individual counting, which is hard to achieve with X-rays. The time scale of CMOS-type cameras doesn't allow one to consider time-of-flight measurements, but kinetic experiments in the 10 ms range are possible. The theory is next confronted to the first experimental results. (authors)

  5. Neutron whispering gallery

    Science.gov (United States)

    Nesvizhevsky, Valery V.; Voronin, Alexei Yu.; Cubitt, Robert; Protasov, Konstantin V.

    2010-02-01

    The `whispering gallery' effect has been known since ancient times for sound waves in air, later in water and more recently for a broad range of electromagnetic waves: radio, optics, Roentgen and so on. It consists of wave localization near a curved reflecting surface and is expected for waves of various natures, for instance, for atoms and neutrons. For matter waves, it would include a new feature: a massive particle would be settled in quantum states, with parameters depending on its mass. Here, we present for the first time the quantum whispering-gallery effect for cold neutrons. This phenomenon provides an example of an exactly solvable problem analogous to the `quantum bouncer'; it is complementary to the recently discovered gravitationally bound quantum states of neutrons . These two phenomena provide a direct demonstration of the weak equivalence principle for a massive particle in a pure quantum state. Deeply bound whispering-gallery states are long-living and weakly sensitive to surface potential; highly excited states are short-living and very sensitive to the wall potential shape. Therefore, they are a promising tool for studying fundamental neutron-matter interactions, quantum neutron optics and surface physics effects.

  6. Neutron Scattering in Hydrogenous Moderators, Studied by Time Dependent Reaction Rate Method

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, L.G.; Moeller, E.; Purohit, S.N.

    1966-03-15

    The moderation and absorption of a neutron burst in water, poisoned with the non-1/v absorbers cadmium and gadolinium, has been followed on the time scale by multigroup calculations, using scattering kernels for the proton gas and the Nelkin model. The time dependent reaction rate curves for each absorber display clear differences for the two models, and the separation between the curves does not depend much on the absorber concentration. An experimental method for the measurement of infinite medium reaction rate curves in a limited geometry has been investigated. This method makes the measurement of the time dependent reaction rate generally useful for thermalization studies in a small geometry of a liquid hydrogenous moderator, provided that the experiment is coupled to programs for the calculation of scattering kernels and time dependent neutron spectra. Good agreement has been found between the reaction rate curve, measured with cadmium in water, and a calculated curve, where the Haywood kernel has been used.

  7. Calorimetric and ionimetric dosimetry intercomparisons II: d + T neutron source at the Antoni Van Leeuwenhoek hospital.

    Science.gov (United States)

    McDonald, J C; Ma, I C; Mijhnheer, B J; Zoetelief, H

    1981-01-01

    A series of dosimetric measurements was carried out at the Antoni van Leeuwenhoek Hospital, Amsterdam, using a Philips d + T generator, which produced neutrons with energies of approximately 14 MeV. A-150 plastic ionization chambers, an A-150 plastic calorimeter, and a GM dosimeter were used to determine total absorbed dose and the photon absorbed dose fraction. The ion chambers were calibrated in a 60Co gamma-ray field in air and compared in a phantom placed in the 60Co gamma-ray beam. Comparison of the total absorbed dose derived from the ionization chamber measurements to that determined using the calorimeter indicated agreement for the neutron measurements between the techniques to within +/- 2%.

  8. Warm Absorber Diagnostics of AGN Dynamics

    Science.gov (United States)

    Kallman, Timothy

    Warm absorbers and related phenomena are observable manifestations of outflows or winds from active galactic nuclei (AGN) that have great potential value. Understanding AGN outflows is important for explaining the mass budgets of the central accreting black hole, and also for understanding feedback and the apparent co-evolution of black holes and their host galaxies. In the X-ray band warm absorbers are observed as photoelectric absorption and resonance line scattering features in the 0.5-10 keV energy band; the UV band also shows resonance line absorption. Warm absorbers are common in low luminosity AGN and they have been extensively studied observationally. They may play an important role in AGN feedback, regulating the net accretion onto the black hole and providing mechanical energy to the surroundings. However, fundamental properties of the warm absorbers are not known: What is the mechanism which drives the outflow?; what is the gas density in the flow and the geometrical distribution of the outflow?; what is the explanation for the apparent relation between warm absorbers and the surprising quasi-relativistic 'ultrafast outflows' (UFOs)? We propose a focused set of model calculations that are aimed at synthesizing observable properties of warm absorber flows and associated quantities. These will be used to explore various scenarios for warm absorber dynamics in order to answer the questions in the previous paragraph. The guiding principle will be to examine as wide a range as possible of warm absorber driving mechanisms, geometry and other properties, but with as careful consideration as possible to physical consistency. We will build on our previous work, which was a systematic campaign for testing important class of scenarios for driving the outflows. We have developed a set of tools that are unique and well suited for dynamical calculations including radiation in this context. We also have state-of-the-art tools for generating synthetic spectra, which are

  9. Ultrathin flexible dual band terahertz absorber

    Science.gov (United States)

    Shan, Yan; Chen, Lin; Shi, Cheng; Cheng, Zhaoxiang; Zang, Xiaofei; Xu, Boqing; Zhu, Yiming

    2015-09-01

    We propose an ultrathin and flexible dual band absorber operated at terahertz frequencies based on metamaterial. The metamaterial structure consists of periodical split ring resonators with two asymmetric gaps and a metallic ground plane, separated by a thin-flexible dielectric spacer. Particularly, the dielectric spacer is a free-standing polyimide film with thickness of 25 μm, resulting in highly flexible for our absorber and making it promising for non-planar applications such as micro-bolometers and stealth aircraft. Experimental results show that the absorber has two resonant absorption frequencies (0.41 THz and 0.75 THz) with absorption rates 92.2% and 97.4%, respectively. The resonances at the absorption frequencies come from normal dipole resonance and high-order dipole resonance which is inaccessible in the symmetrical structure. Multiple reflection interference theory is used to analyze the mechanism of the absorber and the results are in good agreement with simulated and experimental results. Furthermore, the absorption properties are studied under various spacer thicknesses. This kind of metamaterial absorber is insensitive to polarization, has high absorption rates (over 90%) with wide incident angles range from 0° to 45° and the absorption rates are also above 90% when wrapping it to a curved surface.

  10. Oxygen absorbers in food preservation: a review.

    Science.gov (United States)

    Cichello, Simon Angelo

    2015-04-01

    The preservation of packaged food against oxidative degradation is essential to establish and improve food shelf life, customer acceptability, and increase food security. Oxygen absorbers have an important role in the removal of dissolved oxygen, preserving the colour, texture and aroma of different food products, and importantly inhibition of food spoilage microbes. Active packaging technology in food preservation has improved over decades mostly due to the sealing of foods in oxygen impermeable package material and the quality of oxygen absorber. Ferrous iron oxides are the most reliable and commonly used oxygen absorbers within the food industry. Oxygen absorbers have been transformed from sachets of dried iron-powder to simple self-adhesive patches to accommodate any custom size, capacity and application. Oxygen concentration can be effectively lowered to 100 ppm, with applications spanning a wide range of food products and beverages across the world (i.e. bread, meat, fish, fruit, and cheese). Newer molecules that preserve packaged food materials from all forms of degradation are being developed, however oxygen absorbers remain a staple product for the preservation of food and pharmaceutical products to reduce food wastage in developed nations and increased food security in the developing & third world.

  11. Detecting and interpreting statistical lensing by absorbers

    CERN Document Server

    Ménard, B

    2004-01-01

    We propose a method for detecting gravitational magnification of distant sources, like quasars, due to absorber systems detected in their spectra. We first motivate the use of metal absorption lines rather than Lyman-alpha lines, then we show how to relate the observed moments of the source magnitude distribution to the mass distribution of absorbers. In order to illustrate the feasibility of the method, we use a simple model to estimate the amplitude of the effect expected for MgII absorption lines, and show that their lensing signal might already be detectable in large surveys like the SDSS. Our model suggests that quasars behind strong MgII absorbers are in average brightened by -0.05 to -0.2 magnitude due to magnification. One must therefore revisit the claim that, in magnitude limited surveys, quasars with strong absorbers tend to be missed due to extinction effects. In addition to constraining the mass of absorber systems, applying our method will allow for the quantification of this bias.

  12. Distributed Absorber for Noise and Vibration Control

    Directory of Open Access Journals (Sweden)

    Michel Azoulay

    2011-01-01

    Full Text Available An approach to a wide-band frequency passive vibration attenuation is introduced in this paper. This aims to suppress noise and vibration of extended multimode objects like plates, panels and shells. The absorber is arranged in the form of a single-layer assembly of small inertial bodies (balls being distributed and moulded within the light visco-elastic media (e.g. silicone resin. The absorber as a whole is embedded into object face covering the critical patches of the system surface. For the purpose of characterization, the authors introduced the complex frequency response function relating the volume velocity produced by the vibrating object surface (response stimulated by a point-wise force (stimulus applied to a particular point. The simulation and optimization of the main frequency characteristics has been performed using a full scale 3-dimensional Finite Element model. These revealed some new dynamic features of absorber's structures, which can contribute to vibration attenuation. A full-scale physical experimentation with synthesised absorber's structures confirmed the main results of simulation and has shown significant noise reduction over a staggering 0–20 kHz frequency band. This was achieved with a negligible weight and volume penalty due to the addition of the absorber. The results can find multiple applications in noise and vibration control of different structures. Some examples of such applications are presented.

  13. In-phantom spectra and dose distributions from a high-energy neutron therapy beam

    Energy Technology Data Exchange (ETDEWEB)

    Benck, S. E-mail: benck@fynu.ucl.ac.be; D' Errico, F.; Denis, J.-M.; Meulders, J.-P.; Nath, R.; Pitcher, E.J

    2002-01-01

    In radiotherapy with external beams, healthy tissues surrounding the target volumes are inevitably irradiated. In the case of neutron therapy, the estimation of dose to the organs surrounding the target volume is particularly challenging, because of the varying contributions from primary and secondary neutrons and photons of different energies. The neutron doses to tissues surrounding the target volume at the Louvain-la-Neuve (LLN) facility were investigated in this work. At LLN, primary neutrons have a broad spectrum with a mean energy of about 30 MeV. The transport of a 10x10 cm{sup 2} beam through a water phantom was simulated by means of the Monte Carlo code MCNPX. Distributions of energy-differential values of neutron fluence, kerma and kerma equivalent were estimated at different locations in a water phantom. The evolution of neutron dose and dose equivalent inside the phantom was deduced. Measurements of absorbed dose and of dose equivalent were then carried out in a water phantom using an ionization chamber and superheated drop detectors (SDDs). On the beam axis, the calculations agreed well with the ionization chamber data, but disagreed significantly from the SDD data due to the detector's under-response to neutrons above 20 MeV. Off the beam axis, the calculated absorbed doses were significantly lower than the ionization chamber readings, since gamma fields were not accounted for. The calculated data are doses from neutron-induced charge particles, and these agreed with the values measured by the photon-insensitive SDDs. When exposed to the degraded spectra off the beam axis, the SDD offered reliable estimates of the neutron dose equivalent.

  14. Virtual neutron scattering experiments

    DEFF Research Database (Denmark)

    Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael

    2017-01-01

    We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering....... In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus...... on physics and data rather than the overwhelming instrumentation. We argue that this is because they can transfer their virtual experimental experience to the real-life situation. However, we also find that learning is still situated in the sense that only knowledge of particular experiments is transferred...

  15. Virtual neutron scattering experiments

    DEFF Research Database (Denmark)

    Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael

    2016-01-01

    We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering....... In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus...... on physics and data rather than the overwhelming instrumentation. We argue that this is because they can transfer their virtual experimental experience to the real-life situation. However, we also find that learning is still situated in the sense that only knowledge of particular experiments is transferred...

  16. Direction sensitive neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    Ahlen, Steven; Fisher, Peter; Dujmic, Denis; Wellenstein, Hermann F.; Inglis, Andrew

    2017-01-31

    A neutron detector includes a pressure vessel, an electrically conductive field cage assembly within the pressure vessel and an imaging subsystem. A pressurized gas mixture of CF.sub.4, .sup.3He and .sup.4He at respective partial pressures is used. The field cage establishes a relatively large drift region of low field strength, in which ionization electrons generated by neutron-He interactions are directed toward a substantially smaller amplification region of substantially higher field strength in which the ionization electrons undergo avalanche multiplication resulting in scintillation of the CF.sub.4 along scintillation tracks. The imaging system generates two-dimensional images of the scintillation patterns and employs track-finding to identify tracks and deduce the rate and direction of incident neutrons. One or more photo-multiplier tubes record the time-profile of the scintillation tracks permitting the determination of the third coordinate.

  17. Carbon neutron star atmospheres

    CERN Document Server

    Suleimanov, V F; Pavlov, G G; Werner, K

    2013-01-01

    The accuracy of measuring the basic parameters of neutron stars is limited in particular by uncertainties in chemical composition of their atmospheres. For example, atmospheres of thermally - emitting neutron stars in supernova remnants might have exotic chemical compositions, and for one of them, the neutron star in CasA, a pure carbon atmosphere has recently been suggested by Ho & Heinke (2009). To test such a composition for other similar sources, a publicly available detailed grid of carbon model atmosphere spectra is needed. We have computed such a grid using the standard LTE approximation and assuming that the magnetic field does not exceed 10^8 G. The opacities and pressure ionization effects are calculated using the Opacity Project approach. We describe the properties of our models and investigate the impact of the adopted assumptions and approximations on the emergent spectra.

  18. Uniformly rotating neutron stars

    CERN Document Server

    Boshkayev, Kuantay

    2016-01-01

    In this chapter we review the recent results on the equilibrium configurations of static and uniformly rotating neutron stars within the Hartle formalism. We start from the Einstein-Maxwell-Thomas-Fermi equations formulated and extended by Belvedere et al. (2012, 2014). We demonstrate how to conduct numerical integration of these equations for different central densities ${\\it \\rho}_c$ and angular velocities $\\Omega$ and compute the static $M^{stat}$ and rotating $M^{rot}$ masses, polar $R_p$ and equatorial $R_{\\rm eq}$ radii, eccentricity $\\epsilon$, moment of inertia $I$, angular momentum $J$, as well as the quadrupole moment $Q$ of the rotating configurations. In order to fulfill the stability criteria of rotating neutron stars we take into considerations the Keplerian mass-shedding limit and the axisymmetric secular instability. Furthermore, we construct the novel mass-radius relations, calculate the maximum mass and minimum rotation periods (maximum frequencies) of neutron stars. Eventually, we compare a...

  19. Determination of the [gamma]-ray dose in an epithermal neutron beam

    Energy Technology Data Exchange (ETDEWEB)

    Raaijmakers, C.P.J.; Konijnenberg, M.W.; Mijnheer, B.J. (Netherlands Cancer Inst., Amsterdam (Netherlands)); Stecher-Rasmussen, F.; Verhagen, H. (Netherlands Energy Research Foundation, Petten (Netherlands))

    1993-01-01

    Neutron beams used for Boron Neutron Capture Therapy (BNCT) are always accompanied by photons. These two irradiation components have different relative biological effectiveness. Therefore it is necessary to determine the neutron and photon absorbed dose in the mixed field separately. All gamma-ray detectors however are also sensitive for neutrons. In this work preliminary results are presented using TLD-700 chips, a Mg(Ar) ionisation chamber and a GM-counter to determine the gamm-ray component in a mixed beam of gamma-rays and neutrons. The results show a good agreement between the GM-counter and the ionisation chamber, indicating a small realtive neutron sensitivity (k[sub u]) for these detectors. The sensitivity of TLD-700 for thermal neutrons however gives rise to a detector response for which a correction is necessary. The uncertainty however in the relative gamma-ray sensitivity (h[sub u]) of the detectors is at this moment too large to determine accurate values of the relative neutron sensitivities. (orig.).

  20. Neutron scattering in concrete and wood: Part II--Oblique incidence.

    Science.gov (United States)

    Facure, A; Silva, A X; Rivera, J C; Falcão, R C

    2008-01-01

    The knowledge of neutron reflection coefficients is of practical interest when projecting the shielding of radiotherapy rooms, since it is known that about 75% of the neutrons at the maze entrance of these rooms are scattered neutrons. In a previous paper, the energy spectra of photoneutrons were calculated, when reflected by ordinary, high-density concrete and wood barriers, using the MCNP5 code, considering normal incidence and neutron incident energies varying between 0.1 and 10 MeV. It was found that the mean energy of the reflected neutrons does not depend on the reflection angle and that these mean energies are lower in wood and barytes concrete, compared with ordinary concrete. In the present work, the simulation of neutron reflection coefficients were completed, considering the case when these particles do not collide frontally with the barriers, which constitute the radiotherapy room walls. Some simulations were also made to evaluate how neutron equivalent doses at the position of the room door is affected when the maze walls are lined with neutron absorbing materials, such as wood itself or borated polyethylene. Finally, capture gamma rays dose at the entrance of rooms with different maze lengths were also simulated. The results were discussed in the light of the albedo concepts presented in the literature and some of these results were confronted with others, finding good agreement between them.

  1. Secondary neutron doses received by paediatric patients during intracranial proton therapy treatments.

    Science.gov (United States)

    Sayah, R; Farah, J; Donadille, L; Hérault, J; Delacroix, S; De Marzi, L; De Oliveira, A; Vabre, I; Stichelbaut, F; Lee, C; Bolch, W E; Clairand, I

    2014-06-01

    This paper's goal is to assess secondary neutron doses received by paediatric patients treated for intracranial tumours using a 178 MeV proton beam. The MCNPX Monte Carlo model of the proton therapy facility, previously validated through experimental measurements for both proton and neutron dosimetry, was used. First, absorbed dose was calculated for organs located outside the clinical target volume using a series of hybrid computational phantoms for different ages and considering a realistic treatment plan. In general, secondary neutron dose was found to decrease as the distance to the treatment field increases and as the patient age increases. In addition, secondary neutron doses were studied as a function of the beam incidence. Next, neutron equivalent dose was assessed using organ-specific energy-dependent radiation weighting factors determined from Monte Carlo simulations of neutron spectra at each organ. The equivalent dose was found to reach a maximum value of ∼155 mSv at the level of the breasts for a delivery of 49 proton Gy to an intracranial tumour of a one-year-old female patient. Finally, a thorough comparison of the calculation results with published data demonstrated the dependence of neutron dose on the treatment configuration and proved the need for facility-specific and treatment-dependent neutron dose calculations.

  2. Herschel and Spitzer Observations of Slowly Rotating, Nearby Isolated Neutron Stars

    Science.gov (United States)

    Posselt, B.; Pavlov, G. G.; Popov, S.; Wachter, S.

    2014-11-01

    Supernova fallback disks around neutron stars have been suspected to influence the evolution of the diverse neutron star populations. Slowly rotating neutron stars are the most promising places to find such disks. Searching for the cold and warm debris of old fallback disks, we carried out Herschel PACS (70 μm, 160 μm) and Spitzer IRAC (3.6 μm, 4.5 μm) observations of eight slowly rotating (P ≈ 3-11 s) nearby (5σ) at locations consistent with the positions of the neutron stars RX J0806.4-4123 and RX J2143.0+0654. No other significant infrared emission was detected from the eight neutron stars. We estimate probabilities of 63%, 33%, and 3% that, respectively, none, one, or both Herschel PACS 160 μm detections are unrelated excess sources due to background source confusion or an interstellar cirrus. If the 160 μm emission is indeed related to cold (10-22 K) dust around the neutron stars, this dust is absorbing and re-emitting ~10% to ~20% of the neutron stars' X-rays. Such high efficiencies would be at least three orders of magnitude larger than the efficiencies of debris disks around nondegenerate stars. While thin dusty disks around the neutron stars can be excluded as counterparts of the 160 μm emission, dusty asteroid belts constitute a viable option.

  3. Absorbing material based on starch having improved absorbent properties and process for the preparation thereof

    NARCIS (Netherlands)

    Feil, H.; Soest, van J.J.G.; Schijndel, van R.J.G.

    1999-01-01

    A biodegradable, highly water-absorbing polymer based on starch or derivatives thereof is described, wherein the starch has not been chemically modified or only to a degree of substitution below 0.2, and has a water-absorbing power of at least 10 times its own weight, half of the water absorption be

  4. Non-Absorbable Gas Behavior in the Absorber/Evaporator of a Absorption Chiller

    Science.gov (United States)

    Suzuki, Hiroshi; Nagamoto, Wataru; Sugiyama, Takahide

    A two-dimensional numerical study on non-absorbable gas behavior in the absorber/evaporator of an absorption chiller has been performed. In the present study, the effect of the pitch-to-diameter ratio of a cylinder bundle in the absorber was highlighted. From the results, a sudden decrease of the overall heat transfer coefficient of the absorber was observed at a certain mean concentration of non-absorbable gas for each pitch-to-diameter ratio. Such a critical concentration was also found to decrease as the pitch-to- diameter ratio increased. The sudden decrease occurs due to the sudden disappearance of recirculating region, which is formed between the absorber and the evaporator, and where most of non-absorbable gas stays when it exists. As the pitch-to-diameter ratio increases, the recirculating region becomes weak because the velocity of the high velocity region supporting the recirculating flow decreases. Then, the critical mean concentration of non-absorbable gas is found to decrease as pitch-to-ratio increases.

  5. Distributed electric absorbers of beam vibrations

    Science.gov (United States)

    dell'lsola, Francesco; Del Vescovo, Dionisio; Maurini, Corrado

    2003-07-01

    Several electric vibration absorbers based on distributed piezoelectric control of beam vibrations are studied. The damping devices are conceived by interconnecting with different modular electric networks an array of piezoelectric transducers uniformly distributed on a beam. Five different vibration absorbers made of five different network interconnecting topologies are considered and their damping performances are analyzed and compared. The analysis is based on homogenized models of modular piezo-electromechanical systems. The optimal parameters of these absorbers are found by adopting the criterion of critical damping of waves with a single wave number. We show that: i) there is an interconnecting network providing an optimal multimodal damping; ii) the performances required to the electr(on)ic components can be significantly decreased by increasing the number (and decreasing the dimensions) of the piezoelectric transducers.

  6. On the warm absorber in AGN outflow

    CERN Document Server

    Adhikari, T P; Sobolewska, M; Czerny, B

    2016-01-01

    Warm absorber (WA) is an ionised gas present in the line of sight to the AGN central engine. The effect of the absorber is imprinted in the absorption lines observed in X-ray spectra of AGN. In this work, we model the WA in Seyfert 1 galaxy Mrk 509 using its recently published shape of broad band spectral energy distribution (SED) as a continuum illuminating the absorber. Using the photoionization code {\\sc Titan}, recently we have shown that the absorption measure distribution (AMD) found for this object can be successfully modelled as a single slab of gas in total pressure (radiation+gas) equilibrium, contrary to the usual models of constant density multiple slabs. We discuss the transmitted spectrum that would be recorded by an observer after the radiation from the nucleus passes through the WA.

  7. Ferrite HOM Absorber for the RHIC ERL

    Energy Technology Data Exchange (ETDEWEB)

    Hahn,H.; Choi, E.M.; Hammons, L.

    2008-10-01

    A superconducting Energy Recovery Linac is under construction at Brookhaven National Laboratory to serve as test bed for RHIC upgrades. The damping of higher-order modes in the superconducting five-cell cavity for the Energy-Recovery linac at RHIC is performed exclusively by two ferrite absorbers. The ferrite properties have been measured in ferrite-loaded pill box cavities resulting in the permeability values given by a first-order Debye model for the tiled absorber structure and an equivalent permeability value for computer simulations with solid ring dampers. Measured and simulated results for the higher-order modes in the prototype copper cavity are discussed. First room-temperature measurements of the finished niobium cavity are presented which confirm the effective damping of higher-order modes in the ERL. by the ferrite absorbers.

  8. Broadband plasmonic absorber for photonic integrated circuits

    CERN Document Server

    Xiong, Xiao; Ren, Xi-Feng; Guo, Guang-Can

    2013-01-01

    The loss of surface plasmon polaritons has long been considered as a fatal shortcoming in information transport. Here we propose a plasmonic absorber utilizing this "shortcoming" to absorb the stray light in photonic integrated circuits (PICs). Based on adiabatic mode evolution, its performance is insensitive to incident wavelength with bandwidth larger than 300nm, and robust against surrounding environment and temperature. Besides, the use of metal enables it to be very compact and beneficial to thermal dissipation. With this 40um-long absorber, the absorption efficiency can be over 99.8% at 1550nm, with both the reflectivity and transmittance of incident light reduced to less than 0.1%. Such device may find various applications in PICs, to eliminate the residual strong pump laser or stray light.

  9. Interference theory of metamaterial perfect absorbers

    CERN Document Server

    Chen, Hou-Tong

    2011-01-01

    The impedance matching in metamaterial perfect absorbers has been believed to involve and rely on magnetic resonant response, with a direct evidence from the anti-parallel directions of surface currents in the metal structures. Here we present a different theoretical interpretation based on interferences, which shows that the two layers of metal structure in metamaterial absorbers are linked only by multiple reflections with negligible near-field interactions or magnetic resonances. This is further supported by the out-of-phase surface currents derived at the interfaces of resonator array and ground plane through multiple reflections and superpositions. The theory developed here explains all features observed in narrowband metamaterial absorbers and therefore provides a profound understanding of the underlying physics.

  10. Absorber Materials at Room and Cryogenic Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    F. Marhauser, T.S. Elliott, A.T. Wu, E.P. Chojnacki, E. Savrun

    2011-09-01

    We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.

  11. Atmospheres around Neutron Stars

    Science.gov (United States)

    Fryer, Chris L.; Benz, Willy

    1994-12-01

    Interest in the behavior of atmospheres around neutron stars has grown astronomically in the past few years. Some of this interest arrived in the wake of the explosion of Supernova 1987A and its elusive remnant; spawning renewed interest in a method to insure material ``fall-back'' onto the adolescent neutron star in an effort to transform it into a silent black hole. However, the bulk of the activity with atmospheres around neutron stars is concentrated in stellar models with neutron star, rather than white dwarf, cores; otherwise known as Thorne-Zytkow objects. First a mere seed in the imagination of theorists, Thorne-Zytkow objects have grown into an observational reality with an ever-increasing list of formation scenarios and observational prospects. Unfortunately, the analytic work of Chevalier on supernova fall-back implies that, except for a few cases, the stellar simulations of Thorne-Zytkow objects are missing an important aspect of physics: neutrinos. Neutrino cooling removes the pressure support of these atmospheres, allowing accretion beyond the canonical Eddington rate for these objects. We present here the results of detailed hydrodynamical simulations in one and two dimensions with the additional physical effects of neutrinos, advanced equations of state, and relativity over a range of parameters for our atmosphere including entropy and chemical composition as well as a range in the neutron star size. In agreement with Chevalier, we find, under the current list of formation scenarios, that the creature envisioned by Thorne and Zytkow will not survive the enormous appetite of a neutron star. However, neutrino heating (a physical effect not considered in Chevalier's analysis) can play an important role in creating instabilities in some formation schemes, leading to an expulsion of matter rather than rapid accretion. By placing scrutiny upon the formation methods, we can determine the observational prospects for each.

  12. Pixelated neutron image plates

    Science.gov (United States)

    Schlapp, M.; Conrad, H.; von Seggern, H.

    2004-09-01

    Neutron image plates (NIPs) have found widespread application as neutron detectors for single-crystal and powder diffraction, small-angle scattering and tomography. After neutron exposure, the image plate can be read out by scanning with a laser. Commercially available NIPs consist of a powder mixture of BaFBr : Eu2+ and Gd2O3 dispersed in a polymer matrix and supported by a flexible polymer sheet. Since BaFBr : Eu2+ is an excellent x-ray storage phosphor, these NIPs are particularly sensitive to ggr-radiation, which is always present as a background radiation in neutron experiments. In this work we present results on NIPs consisting of KCl : Eu2+ and LiF that were fabricated into ceramic image plates in which the alkali halides act as a self-supporting matrix without the necessity for using a polymeric binder. An advantage of this type of NIP is the significantly reduced ggr-sensitivity. However, the much lower neutron absorption cross section of LiF compared with Gd2O3 demands a thicker image plate for obtaining comparable neutron absorption. The greater thickness of the NIP inevitably leads to a loss in spatial resolution of the image plate. However, this reduction in resolution can be restricted by a novel image plate concept in which a ceramic structure with square cells (referred to as a 'honeycomb') is embedded in the NIP, resulting in a pixelated image plate. In such a NIP the read-out light is confined to the particular illuminated pixel, decoupling the spatial resolution from the optical properties of the image plate material and morphology. In this work, a comparison of experimentally determined and simulated spatial resolutions of pixelated and unstructured image plates for a fixed read-out laser intensity is presented, as well as simulations of the properties of these NIPs at higher laser powers.

  13. POLARIZED NEUTRONS IN RHIC

    Energy Technology Data Exchange (ETDEWEB)

    COURANT,E.D.

    1998-04-27

    There does not appear to be any obvious way to accelerate neutrons, polarized or otherwise, to high energies by themselves. To investigate the behavior of polarized neutrons the authors therefore have to obtain them by accelerating them as components of heavier nuclei, and then sorting out the contribution of the neutrons in the analysis of the reactions produced by the heavy ion beams. The best neutron carriers for this purpose are probably {sup 3}He nuclei and deuterons. A polarized deuteron is primarily a combination of a proton and a neutron with their spins pointing in the same direction; in the {sup 3}He nucleus the spins of the two protons are opposite and the net spin (and magnetic moment) is almost the same as that of a free neutron. Polarized ions other than protons may be accelerated, stored and collided in a ring such as RHIC provided the techniques proposed for polarized proton operation can be adapted (or replaced by other strategies) for these ions. To accelerate polarized particles in a ring, one must make provisions for overcoming the depolarizing resonances that occur at certain energies. These resonances arise when the spin tune (ratio of spin precession frequency to orbit frequency) resonates with a component present in the horizontal field. The horizontal field oscillates with the vertical motion of the particles (due to vertical focusing); its frequency spectrum is dominated by the vertical oscillation frequency and its modulation by the periodic structure of the accelerator ring. In addition, the magnet imperfections that distort the closed orbit vertically contain all integral Fourier harmonics of the orbit frequency.

  14. Precise dispersion equations of absorbing filter glasses

    Science.gov (United States)

    Reichel, S.; Biertümpfel, Ralf

    2014-05-01

    The refractive indices versus wavelength of optical transparent glasses are measured at a few wavelengths only. In order to calculate the refractive index at any wavelength, a so-called Sellmeier series is used as an approximation of the wavelength dependent refractive index. Such a Sellmeier representation assumes an absorbing free (= loss less) material. In optical transparent glasses this assumption is valid since the absorption of such transparent glasses is very low. However, optical filter glasses have often a rather high absorbance in certain regions of the spectrum. The exact description of the wavelength dependent function of the refractive index is essential for an optimized design for sophisticated optical applications. Digital cameras use an IR cut filter to ensure good color rendition and image quality. In order to reduce ghost images by reflections and to be nearly angle independent absorbing filter glass is used, e.g. blue glass BG60 from SCHOTT. Nowadays digital cameras improve their performance and so the IR cut filter needs to be improved and thus the accurate knowledge of the refractive index (dispersion) of the used glasses must be known. But absorbing filter glass is not loss less as needed for a Sellmeier representation. In addition it is very difficult to measure it in the absorption region of the filter glass. We have focused a lot of effort on measuring the refractive index at specific wavelength for absorbing filter glass - even in the absorption region. It will be described how to do such a measurement. In addition we estimate the use of a Sellmeier representation for filter glasses. It turns out that in most cases a Sellmeier representation can be used even for absorbing filter glasses. Finally Sellmeier coefficients for the approximation of the refractive index will be given for different filter glasses.

  15. New compact neutron polarizer

    Science.gov (United States)

    Krist, Th; Kennedy, S. J.; Hicks, T. J.; Mezei, F.

    A new type of a neutron polarizing bender was developed in co-operation with BENSC and ANSTO. It is based upon bent thin silicon wafers coated on one side with SiFeCo polarizing supermirrors and on the other side with Gd. Initial tests at BENSC in a 300 Oe magnetic field yielded a transmission of spin-up neutrons of about 55% over an angle range of 0.75° and flipping ratios > 30. Subsequent tests at ANSTO at 1200 Oe yielded a transmission of 48% with a flipping ratio > 45.

  16. FAST NEUTRONIC REACTOR

    Science.gov (United States)

    Snell, A.H.

    1957-12-01

    This patent relates to a reactor and process for carrying out a controlled fast neutron chain reaction. A cubical reactive mass, weighing at least 920 metric tons, of uranium metal containing predominantly U/sup 238/ and having a U/sup 235/ content of at least 7.63% is assembled and the maximum neutron reproduction ratio is limited to not substantially over 1.01 by insertion and removal of a varying amount of boron, the reactive mass being substantially freed of moderator.

  17. Cubic Phases in the Gd2O3-ZrO2 and Dy2O3-TiO2 Systems for Nuclear Industry Applications

    Directory of Open Access Journals (Sweden)

    Maria Teresa Malachevsky

    2015-01-01

    Full Text Available Neutron absorbers are elements with a high neutron capture cross section that are employed at nuclear reactors to control excess fuel reactivity. If these absorbers are converted into materials of relatively low absorption cross section as the result of neutron absorption, they consume during the reactor core life and so are called burnable. These elements can be distributed inside an oxide ceramic that is stable under irradiation and thus called inert. Cubic zirconium oxide is one of the preferred materials to be used as inert matrix. It is stable under irradiation, experiments very low swelling, and is isomorphic to uranium oxide. The cubic phase is stabilized by adding small amounts of dopants like Dy2O3 and Gd2O3. As both dysprosium and gadolinium have a high neutron cross section, they are good candidates to prepare burnable neutron absorbers. Pyrochlores, like Gd2Zr2O7 and Dy2Ti2O7, allow the solid solution of a large quantity of elements besides being stable under irradiation. These characteristics make them also useful for safe storage of nuclear wastes. We present a preliminary study of the thermal analysis of different compositions in the systems Gd2O3-ZrO2 and Dy2O3-TiO2, investigating the feasibility to obtain oxide ceramics useful for the nuclear industry.

  18. Helium 3 neutron precision polarimetry

    Science.gov (United States)

    Menard, Christopher

    2009-10-01

    Measuring neutron polarization to a high degree of precision is critical for the next generation of neutron decay correlation experiments. Polarized neutrons are also used in experiments to probe the hadronic weak interaction which contributes a small portion (˜10-7) of the force between nucleons. Using a beam of cold neutrons at Los Alamos Neutron Science Center (LANSCE), we polarized neutrons and measured their absolute polarization to ˜0.1%. Neutrons were polarized by passing them through a ^3He spin filter, relying on the maximally spin dependent 3He neutron absorption cross section. The neutron polarization can be determined by measuring the wavelength-dependent neutron transmission through the ^3He cell. An independent measurement of the neutron polarization was also obtained by passing the polarized beam through an RF spin flipper and a second polarized ^3He cell, used as an analyzer. To measure the efficiency of the spin flipper, the same measurements were made after reversing the ^3He polarization in the polarizer by using NMR techniques (adiabatic fast passage). We will show the consistency of these two measurements and the resulting precision of neutron polarimetry using these techniques.

  19. Durability of Polymeric Glazing and Absorber Materials

    Energy Technology Data Exchange (ETDEWEB)

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Lindquist, C.; Milbourne, M.

    2005-11-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. We have begun evaluation of several new UV-screened polycarbonate sheet glazing constructions. This has involved interactions with several major polymer industry companies to obtain improved candidate samples. Proposed absorber materials were tested for UV resistance, and appear adequate for unglazed ICS absorbers.

  20. Timing the warm absorber in NGC 4051

    Science.gov (United States)

    Silva, C. V.; Uttley, P.; Costantini, E.

    2016-12-01

    We investigated, using spectral-timing analysis, the characterization of highly ionized outflows in Seyfert galaxies, the so-called warm absorbers. Here, we present our results of the extensive 600 ks of XMM-Newton archival observations of the bright and highly variable Seyfert 1 galaxy NGC 4051 whose spectrum has revealed a complex multicomponent wind. Making use of both RGS and EPIC-pn data, we performed a detailed analysis through a time-dependent photoionization code in combination with spectral and Fourier spectral-timing techniques. The source light curves and the warm absorber parameters obtained from the data were used to simulate the response of the gas to variations in the ionizing flux of the central source. The resulting time variable spectra were employed to predict the effects of the warm absorber on the time lags and coherence of the energy dependent light curves. We have found that, in the absence of any other lag mechanisms, a warm absorber with the characteristics of the one observed in NGC 4051, is able to produce soft lags, up to 100 s, on timescales of hours. The time delay is associated with the response of the gas to changes in the ionizing source, either by photoionization or radiative recombination, which is dependent on its density. The range of radial distances that, under our assumptions, yield longer time delays are distances r 0.3-1.0 × 1016 cm, and hence gas densities n 0.4-3.0 × 107 cm-3. Since these ranges are comparable to the existing estimates of the location of the warm absorber in NGC 4051, we suggest that it is likely that the observed X-ray time lags may carry a signature of the warm absorber response time to changes in the ionizing continuum. Our results show that the warm absorber in NGC 4051 does not introduce lags on the short timescales associated with reverberation, but will likely modify the hard continuum lags seen on longer timescales, which in this source have been measured to be on the order of 50 s. Hence, these

  1. Shock-Absorbent Ball-Screw Mechanism

    Science.gov (United States)

    Hirr, Otto A., Jr.; Meneely, R. W.

    1986-01-01

    Actuator containing two ball screws in series employs Belleville springs to reduce impact loads, thereby increasing life expectancy. New application of springs increases reliability of equipment in which ball screws commonly used. Set of three springs within lower screw of ball-screw mechanism absorbs impacts that result when parts reach their upper and lower limits of movement. Mechanism designed with Belleville springs as shock-absorbing elements because springs have good energy-to-volume ratio and easily stacked to attain any stiffness and travel.

  2. Spin Particle in an Absorbing Environment

    Science.gov (United States)

    Amooshahi, M.

    2015-10-01

    The quantum dynamics of a localized spin Particle interacting with an absorbing environment is investigated. The quantum Langevin-Schrödinger equation for spin is obtained. The susceptibility function of the environment is calculated in terms of the coupling function of the spin and the environment. it is shown that the susceptibility function satisfies the Kramers-Kronig relations. Spontaneous emission and the shift frequency of the spin is obtained in terms of the imaginary part of the susceptibility function in frequency domain. Some transition probabilities between the spin states are calculated when the absorbing environment is in the thermal state.

  3. Quantum walk with one variable absorbing boundary

    Science.gov (United States)

    Wang, Feiran; Zhang, Pei; Wang, Yunlong; Liu, Ruifeng; Gao, Hong; Li, Fuli

    2017-01-01

    Quantum walks constitute a promising ingredient in the research on quantum algorithms; consequently, exploring different types of quantum walks is of great significance for quantum information and quantum computation. In this study, we investigate the progress of quantum walks with a variable absorbing boundary and provide an analytical solution for the escape probability (the probability of a walker that is not absorbed by the boundary). We simulate the behavior of escape probability under different conditions, including the reflection coefficient, boundary location, and initial state. Moreover, it is also meaningful to extend our research to the situation of continuous-time and high-dimensional quantum walks.

  4. Neutron storage time measurement for the neutron EDM experiment

    Science.gov (United States)

    Griffith, W. Clark; Ito, Takeyasu; Ramsey, John; Makela, Mark; Clayton, Steven; Hennings-Yeomans, Raul; Saidur Rahaman, M.; Currie, Scott; Womack, Todd; Sondheim, Walter; Cooper, Martin

    2010-11-01

    A new experiment to search for the neutron electric dipole moment (nEDM) is under development for installation at the Spallation Neutron Source (SNS) at Oakridge National Laboratory. The experiment will use ultra-cold neutrons (UCN) stored in superfluid helium, along with ^3He atoms acting as a neutron spin analyzer and comagnetometer. One crucial factor affecting the ultimate sensitivity of the experiment is the neutron storage time that can be obtained in the acrylic measurement cell. The acrylic cell walls will be coated with deuterated polystyrene (dPS), which is expected to give a wall loss factor of ˜room temperature and below 20 K.

  5. Neutron recognition in LAND detector for large neutron multiplicity

    CERN Document Server

    Pawłowski, P; Leifels, Y; Trautmann, W; Adrich, P; Aumann, T; Bacri, C O; Barczyk, T; Bassini, R; Bianchin, S; Boiano, C; Boretzky, K; Boudard, A; Chbihi, A; Cibor, J; Czech, B; De Napoli, M; Ducret, J -E; Emling, H; Frankland, J D; Gorbinet, T; Hellström, M; Henzlova, D; Hlavac, S; Immè, J; Iori, I; Johansson, H; Kezzar, K; Kupny, S; Lafriakh, A; Fèvre, A Le; Gentil, E Le; Leray, S; Łukasik, J; Lühning, J; Lynch, W G; Lynen, U; Majka, Z; Mocko, M; Müller, W F J; Mykulyak, A; Orth, H; Otte, A N; Palit, R; Panebianco, S; Pullia, A; Raciti, G; Rapisarda, E; Rossi, D; Salsac, M -D; Sann, H; Schwarz, C; Simon, H; Sfienti, C; Sümmerer, K; Tsang, M B; Verde, G; Veselsky, M; Volant, C; Wallace, M; Weick, H; Wiechula, J; Wieloch, A; Zwiegliński, B

    2012-01-01

    The performance of the LAND neutron detector is studied. Using an event-mixing technique based on one-neutron data obtained in the S107 experiment at the GSI laboratory, we test the efficiency of various analytic tools used to determine the multiplicity and kinematic properties of detected neutrons. A new algorithm developed recently for recognizing neutron showers from spectator decays in the ALADIN experiment S254 is described in detail. Its performance is assessed in comparison with other methods. The properties of the observed neutron events are used to estimate the detection efficiency of LAND in this experiment.

  6. Neutron beam imaging at neutron spectrometers at Dhruva

    Science.gov (United States)

    Desai, Shraddha S.; Rao, Mala N.

    2012-06-01

    A low efficiency, 2-Dimensional Position Sensitive Neutron Detector based on delay line position encoding is developed. It is designed to handle beam flux of 106-107 n/cm2/s and for monitoring intensity profiles of neutron beams. The present detector can be mounted in transmission mode, as the hardware allows maximum neutron transmission in sensitive region. Position resolution of 1.2 mm in X and Y directions, is obtained. Online monitoring of beam images and intensity profile of various neutron scattering spectrometers at Dhruva are presented. It shows better dynamic range of intensity over commercial neutron camera and is also time effective over the traditionally used photographic method.

  7. Some Implications of Neutron Mirror Neutron Oscillation

    CERN Document Server

    Mohapatra, Rabindra N; Nussinov, S

    2005-01-01

    We comment on a recently discussed possibility of oscillations between neutrons and degenerate mirror neutrons in the context of mirror models for particles and forces. It has been noted by Bento and Berezhiani that if these oscillations occurred at a rate of $\\tau^{-1}_{NN'}\\sim sec^{-1}$, it would help explain putative super GKZ cosmic ray events provided the temperature of the mirror radiation is $\\sim 0.3-0.4$ times that of familiar cosmic microwave background radiation. We discuss how such oscillation time scales can be realized in mirror models and find that the simplest nonsupersymmetric model for this idea requires the existence of a low mass (30-3000 GeV) color triplet scalar or vector boson. A supersymmetric model, where this constraint can be avoided is severely constrained by the requirement of maintaining a cooler mirror sector. We also find that the reheat temperature after inflation in generic models that give fast $n-n'$ oscillation be less than about 100 GeV in order to maintain the required ...

  8. 21 CFR 880.6025 - Absorbent tipped applicator.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Absorbent tipped applicator. 880.6025 Section 880... Devices § 880.6025 Absorbent tipped applicator. (a) Identification. An absorbent tipped applicator is a device intended for medical purposes that consists of an absorbent swab on a wooden, paper, or...

  9. 21 CFR 880.5300 - Medical absorbent fiber.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Medical absorbent fiber. 880.5300 Section 880.5300... Devices § 880.5300 Medical absorbent fiber. (a) Identification. A medical absorbent fiber is a device...'s body surface. Absorbent fibers intended solely for cosmetic purposes are not included in...

  10. Neutron Scattering Investigations of Correlated Electron Systems and Neutron Instrumentation

    DEFF Research Database (Denmark)

    Holm, Sonja Lindahl

    are a unique probe for studying the atomic and molecular structure and dynamics of materials. Even though neutrons are very expensive to produce, the advantages neutrons provide overshadow the price. As neutrons interact weakly with materials compared to many other probes, e.g. electrons or photons......, it is possible to make a neutron scattering experiment through sample environment equipment like cryostats or pressure cells. Another advantage of neutron experiments is that the wavelength and energy of the neutron match the inter-atomic distances and basic excitations of solid materials. The scattering cross...... is not taken into account in previous reports on the field effect of magnetic scattering, since usually only L 0 is probed. A paper draft submitted for publication describing the results of elastic and inelastic neutron scattering experiments performed on the oxygen-doped La2CuO4+y HTSC is appended (Tc 40 K...

  11. Neutronic studies of the coupled moderators for spallation neutron sources

    Institute of Scientific and Technical Information of China (English)

    Yin Wen; Liang Jiu-Qing

    2005-01-01

    We investigate the neutronic performance of coupled moderators to be implemented in spallation neutron sources by Monte-Carlo simulation and give the slow neutron spectra for the cold and thermal moderators. CH4 moderator can provide slow neutrons with highly desirable characteristics and will be used in low-power spallation neutron soureces. The slow neutron intensity extracted from different angles has been calculated. The capability of moderation of liquid H2 is lower than H2O and liquid CH4 due to lower atomic number density of hydrogen but we can compensate for this disadvantage by using a premoderator. The H2O premoderator of 2cm thickness can reduce the heat deposition in the cold moderator by about 33% without spoiling the neutron pulse.

  12. Development and qualification of reference calculation schemes for absorbers in pressured water reactor; Elaboration et qualification de schemas de calcul de reference pour les absorbants dans les reacteurs a eau pressurisee

    Energy Technology Data Exchange (ETDEWEB)

    Blanc-Tranchant, P

    2001-07-01

    The general field in which this work takes place is the field of the accuracy improvement of neutronic calculations, required to operate Pressurized Water Reactors (PWR) with a better precision and a lower cost. More specifically, this thesis deals with the calculation of the absorber clusters used to control these reactors. The first aim of that work was to define and validate a reference calculation route of such an absorber cluster, based on the deterministic code APOLLO2. This calculation scheme was then to be checked against experimental data. This study of the complex situation of absorber clusters required several intermediate studies, of simpler problems, such as the study of fuel rods lattices and the study of single absorber rods (B4C, AIC, Hafnium) isolated in such lattices. Each one of these different studies led to a particular reference calculation route. All these calculation routes were developed against reference continuous energy Monte-Carlo calculations, carried out with the stochastic code TRIPOLI4. They were then checked against experimental data measured during French experimental programs, undertaken within the EOLE experimental reactor, at the Nuclear Research Center of Cadarache: the MISTRAL experiments for the study of isolated absorber rods and the EPICURE experiments for the study of absorber clusters. This work led to important improvements in the calculation of isolated absorbers and absorber clusters. The reactivity worth of these clusters in particular, can now be obtained with a great accuracy: the discrepancy observed between the calculated and the experimental values is less than 2.5 %, and then slightly lower than the experimental uncertainty. (author)

  13. Elaboration and qualification of a reference calculation routes for the absorbers in the PWR reactors; Elaboration et qualification des schemas de calcul de reference pour les absorbants dans les reacteurs a eau pressurisee

    Energy Technology Data Exchange (ETDEWEB)

    Blanc-Tranchant, P

    1999-11-01

    The general field in which this work takes place is the field of the accuracy improvement of neutronic calculations, required to operate Pressurized Water Reactors (PWR) with a better precision and a lower cost. More specifically, this thesis deals with the calculation of the absorber clusters used to control these reactors. The first aim of that work was to define and validate a reference calculation route of such an absorber cluster, based on the deterministic code Apollo 2. This calculation scheme was then to be checked against experimental data. This study of the complex situation of absorber clusters required several intermediate studies, of simpler problems, such as the study of fuel rods lattices and the study of single absorber rods (B{sub 4}C, AIC, Hafnium) isolated in such lattices. Each one of these different studies led to a particular reference calculation route. All these calculation routes were developed against reference continuous energy Monte-Carlo calculations, carried out with the stochastic code TRIPOLI14. They were then checked against experimental data measured during french experimental programs, undertaken within the EOLE experimental reactor, at the Nuclear Research Center of Cadarache: the MISTRAL experiments for the study of isolated absorber rods and the EPICURE experiments for the study of absorber clusters. This work led to important improvements in the calculation of isolated absorbers and absorber clusters. The reactivity worth of these clusters in particular, can now be obtained with a great accuracy: the discrepancy observed between the calculated and the experimental values is less than 2.5 %, and then slightly lower than the experimental uncertainty. (author)

  14. Reconciling Coulomb breakup and neutron radiative capture

    Science.gov (United States)

    Capel, P.; Nollet, Y.

    2017-07-01

    The Coulomb-breakup method to extract the cross section for neutron radiative capture at astrophysical energies is analyzed in detail. In particular, its sensitivity to the description of the neutron-core continuum is ascertained. We consider the case of 14C(n ,γ )15C for which both the radiative capture at low energy and the Coulomb breakup of 15C into 14C+n on Pb at 68 MeV/nucleon have been measured with accuracy. We confirm the direct proportionality of the cross section for both reactions to the square of the asymptotic normalization constant of 15C observed by Summers and Nunes [Phys. Rev. C 78, 011601(R) (2008), 10.1103/PhysRevC.78.011601], but we also show that the 14C-n continuum plays a significant role in the calculations. Fortunately, the method proposed by Summers and Nunes can be improved to absorb that continuum dependence. We show that a more precise radiative-capture cross section can be extracted selecting the breakup data at forward angles and low 14C-n relative energies.

  15. A review on neutron reflectometry

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Soo; Lee, Chang Hee; Shim, Hae Seop; Seong, Baek Seok

    1999-03-01

    This report contains principle and characteristic of neutron reflectometry. Therefore, in case of operating neutron reflectometer at HANARO in future, it will be a reference to the user who wishes to use the instrument effectively. Also, the current situation of neutron reflectometer operating in the world was examined. The detail of neutron reflectometer such as GANS(MURR), ADAM(ILL), POSY II(ANL), ROG(IRI) was described. The recent research situation on neutron reflectometry was also examined and it helps us to determine research field. (author)

  16. Neutron proton crystallography station (PCS)

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, Zoe [Los Alamos National Laboratory; Kovalevsky, Andrey [Los Alamos National Laboratory; Johnson, Hannah [Los Alamos National Laboratory; Mustyakimov, Marat [Los Alamos National Laboratory

    2009-01-01

    The PCS (Protein Crystallography Station) at Los Alamos Neutron Science Center (LANSCE) is a unique facility in the USA that is designed and optimized for detecting and collecting neutron diffraction data from macromolecular crystals. PCS utilizes the 20 Hz spallation neutron source at LANSCE to enable time-of-flight measurements using 0.6-7.0 {angstrom} neutrons. This increases the neutron flux on the sample by using a wavelength range that is optimal for studying macromolecular crystal structures. The diagram below show a schematic of PCS and photos of the detector and instrument cave.

  17. Neutron detection efficiency determinations for the TUNL neutron-neutron and neutron-proton scattering-length measurements

    Energy Technology Data Exchange (ETDEWEB)

    Trotter, D.E. Gonzalez [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)], E-mail: crowell@tunl.duke.edu; Meneses, F. Salinas [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Tornow, W. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)], E-mail: tornow@tunl.duke.edu; Crowell, A.S.; Howell, C.R. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Schmidt, D. [Physikalisch-Technische Bundesanstalt, D-38116, Braunschweig (Germany); Walter, R.L. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)

    2009-02-11

    The methods employed and the results obtained from measurements and calculations of the detection efficiency for the neutron detectors used at Triangle Universities Nuclear Laboratory (TUNL) in the simultaneous determination of the {sup 1}S{sub 0} neutron-neutron and neutron-proton scattering lengths a{sub nn} and a{sub np}, respectively, are described. Typical values for the detector efficiency were 0.3. Very good agreement between the different experimental methods and between data and calculation has been obtained in the neutron energy range below E{sub n}=13MeV.

  18. Cooling of Neutron Stars

    Directory of Open Access Journals (Sweden)

    Grigorian H.

    2010-10-01

    Full Text Available We introduce the theoretical basis for modeling the cooling evolution of compact stars starting from Boltzmann equations in curved space-time. We open a discussion on observational verification of different neutron star models by consistent statistics. Particular interest has the question of existence of quark matter deep inside of compact object, which has to have a specific influence on the cooling history of the star. Besides of consideration of several constraints and features of cooling evolution, which are susceptible of being critical for internal structure of hot compact stars we have introduced a method of extraction of the mass distribution of the neutron stars from temperature and age data. The resulting mass distribution has been compared with the one suggested by supernove simulations. This method can be considered as an additional checking tool for the consistency of theoretical modeling of neutron stars. We conclude that the cooling data allowed existence of neutron stars with quark cores even with one-flavor quark matter.

  19. New Neutron Dosimeter

    CERN Multimedia

    2001-01-01

    CERN has been operating an Individual Dosimetry Service for neutrons for about 35 years. The service was based on nuclear emulsions in the form of film packages which were developed and scanned in the Service. In 1999, the supplier of theses packages informed CERN that they will discontinue production of this material. TIS-RP decided to look for an external service provider for individual neutron dosimetry. After an extensive market survey and an invitation for tender, a supplier that met the stringent technical requirements set up by CERN's host states for personal dosimeters was identified. The new dosimeter is based on a track-etching technique. Neutrons have the capability of damaging plastic material. The microscopic damage centres are revealed by etching them in a strong acid. The resulting etch pits can be automatically counted and their density is proportional to dose equivalent from neutrons. On the technical side, the new dosimeter provides an improved independence of its response from energy and th...

  20. Neutron protein crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Niimura, Nobuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-10-01

    X-ray diffraction of single crystal has enriched the knowledge of various biological molecules such as proteins, DNA, t-RNA, viruses, etc. It is difficult to make structural analysis of hydrogen atoms in a protein using X-ray crystallography, whereas neutron diffraction seems usable to directly determine the location of those hydrogen atoms. Here, neutron diffraction method was applied to structural analysis of hen egg-white lysozyme. Since the crystal size of a protein to analyze is generally small (5 mm{sup 3} at most), the neutron beam at the sample position in monochromator system was set to less than 5 x 5 mm{sup 2} and beam divergence to 0.4 degree or less. Neutron imaging plate with {sup 6}Li or Gd mixed with photostimulated luminescence material was used and about 2500 Bragg reflections were recorded in one crystal setting. A total of 38278 reflections for 2.0 A resolution were collected in less than 10 days. Thus, stereo views of Trp-111 omit map around the indol ring of Trp-111 was presented and the three-dimensional arrangement of 696H and 264D atoms in the lysozyme molecules was determined using the omit map. (M.N.)

  1. Tunable metamaterial dual-band terahertz absorber

    Science.gov (United States)

    Luo, C. Y.; Li, Z. Z.; Guo, Z. H.; Yue, J.; Luo, Q.; Yao, G.; Ji, J.; Rao, Y. K.; Li, R. K.; Li, D.; Wang, H. X.; Yao, J. Q.; Ling, F. R.

    2015-11-01

    We report a design of a temperature controlled tunable dual band terahertz absorber. The compact single unit cell consists of two nested closed square ring resonators and a layer metallic separated by a substrate strontium titanate (STO) dielectric layer. It is found that the absorber has two distinctive absorption peaks at frequencies 0.096 THz and 0.137 THz, whose peaks are attained 97% and 75%. Cooling the absorber from 400 K to 250 K causes about 25% and 27% shift compared to the resonance frequency of room temperature, when we cooling the temperature to 150 K, we could attained both the two tunabilities exceeding 53%. The frequency tunability is owing to the variation of the dielectric constant of the low-temperature co-fired ceramic (LTCC) substrate. The mechanism of the dual band absorber is attributed to the overlapping of dual resonance frequencies, and could be demonstrated by the distributions of the electric field. The method opens up avenues for designing tunable terahertz devices in detection, imaging, and stealth technology.

  2. Review of Plasmonic Nanocomposite Metamaterial Absorber

    Directory of Open Access Journals (Sweden)

    Mehdi Keshavarz Hedayati

    2014-02-01

    Full Text Available Plasmonic metamaterials are artificial materials typically composed of noble metals in which the features of photonics and electronics are linked by coupling photons to conduction electrons of metal (known as surface plasmon. These rationally designed structures have spurred interest noticeably since they demonstrate some fascinating properties which are unattainable with naturally occurring materials. Complete absorption of light is one of the recent exotic properties of plasmonic metamaterials which has broadened its application area considerably. This is realized by designing a medium whose impedance matches that of free space while being opaque. If such a medium is filled with some lossy medium, the resulting structure can absorb light totally in a sharp or broad frequency range. Although several types of metamaterials perfect absorber have been demonstrated so far, in the current paper we overview (and focus on perfect absorbers based on nanocomposites where the total thickness is a few tens of nanometer and the absorption band is broad, tunable and insensitive to the angle of incidence. The nanocomposites consist of metal nanoparticles embedded in a dielectric matrix with a high filling factor close to the percolation threshold. The filling factor can be tailored by the vapor phase co-deposition of the metallic and dielectric components. In addition, novel wet chemical approaches are discussed which are bio-inspired or involve synthesis within levitating Leidenfrost drops, for instance. Moreover, theoretical considerations, optical properties, and potential application of perfect absorbers will be presented.

  3. Microstructured extremely thin absorber solar cells

    DEFF Research Database (Denmark)

    Biancardo, Matteo; Krebs, Frederik C

    2007-01-01

    In this paper we present the realization of extremely thin absorber (ETA) solar cells employing conductive glass substrates functionalized with TiO2 microstructures produced by embossing. Nanocrystalline or compact TiO2 films on Indium doped tin oxide (ITO) glass substrates were embossed...

  4. Methods of calculating radiation absorbed dose.

    Science.gov (United States)

    Wegst, A V

    1987-01-01

    The new tumoricidal radioactive agents being developed will require a careful estimate of radiation absorbed tumor and critical organ dose for each patient. Clinical methods will need to be developed using standard imaging or counting instruments to determine cumulated organ activities with tracer amounts before the therapeutic administration of the material. Standard MIRD dosimetry methods can then be applied.

  5. Can polar bear hairs absorb environmental energy?

    Directory of Open Access Journals (Sweden)

    He Ji-Huan

    2011-01-01

    Full Text Available A polar bear (Ursus maritimus has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  6. Timing the warm absorber in NGC 4051

    CERN Document Server

    Silva, Catia; Costantini, Elisa

    2016-01-01

    We investigated, using spectral-timing analysis, the characterization of highly ionized outflows in Seyfert galaxies, the so-called warm absorbers. Here, we present our results on the extensive ~ 600 ks of XMM-Newton archival observations of the bright and highly variable Seyfert 1 galaxy NGC 4051, whose spectrum has revealed a complex multicomponent wind. Making use of both RGS and EPIC-pn data, we performed a detailed analysis through a time-dependent photoionization code in combination with spectral and Fourier spectral-timing techniques. The source light curves and the warm absorber parameters obtained from the data were used to simulate the response of the gas due to variations in the ionizing flux of the central source. The resulting time variable spectra were employed to predict the effects of the warm absorber on the time lags and coherence of the energy dependent light curves. We have found that, in the absence of any other lag mechanisms, a warm absorber with the characteristics of the one observed ...

  7. Can polar bear hairs absorb environmental energy?

    OpenAIRE

    He Ji-Huan; Wang Qing-Li; Sun Jie

    2011-01-01

    A polar bear (Ursus maritimus) has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  8. Fabrication of high efficacy selective solar absorbers

    CSIR Research Space (South Africa)

    Tile, N

    2012-03-01

    Full Text Available High efficiency tandem selective solar absorber materials of carbon in nickel oxide (C-NiO) composite were fabricated on an aluminium substrate using a simple and cost effective sol-gel process. The process involved preparation of carbon and nickel...

  9. Moving core beam energy absorber and converter

    Science.gov (United States)

    Degtiarenko, Pavel V.

    2012-12-18

    A method and apparatus for the prevention of overheating of laser or particle beam impact zones through the use of a moving-in-the-coolant-flow arrangement for the energy absorbing core of the device. Moving of the core spreads the energy deposition in it in 1, 2, or 3 dimensions, thus increasing the effective cooling area of the device.

  10. Semiconductor saturable absorbers for ultrafast terahertz signals

    DEFF Research Database (Denmark)

    Hoffmann, Matthias C.; Turchinovich, Dmitry

    2010-01-01

    We demonstrate saturable absorber behavior of n-type semiconductors GaAs, GaP, and Ge in the terahertz THz frequency range at room temperature using nonlinear THz spectroscopy. The saturation mechanism is based on a decrease in electron conductivity of semiconductors at high electron momentum sta...

  11. Evaluation of energy responses for neutron dose-equivalent meters made in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Saegusa, J. E-mail: saegusa@popsvr.tokai.jaeri.go.jp; Yoshizawa, M.; Tanimura, Y.; Yoshida, M.; Yamano, T.; Nakaoka, H

    2004-01-01

    Energy responses of three types of Japanese neutron dose-equivalent (DE) meters were evaluated by Monte Carlo simulations and measurements. The energy responses were evaluated for thermal neutrons, monoenergetic neutrons with energies up to 15.2 MeV, and also for neutrons from such radionuclide sources as {sup 252}Cf and {sup 241}Am-Be. The calculated results were corroborated with the measured ones. The angular dependence of the response and the DE response were also evaluated. As a result, reliable energy responses were obtained by careful simulations of the proportional counter, moderator and absorber of the DE meters. Furthermore, the relationship between pressure of counting gas and response of the DE meter was discussed. By using the obtained responses, relations between predicted readings of the DE meters and true DE values were studied for various workplace spectra.

  12. Neutron detection on the Foton-M2 satellite by a track etch detector stack.

    Science.gov (United States)

    Pálfalvi, J K; Szabó, J; Dudás, B

    2007-01-01

    In the frame of a European Space Agency (ESA) project called 'Biology and Physics in Space', a returning satellite, Foton-M2, was orbiting a container, the BIOPAN-5, loaded with biological experiments and facilities for radiation dosimetry (RADO) in the open space. One of the RADO experiments was dedicated to the detection of the primary cosmic rays and secondary neutrons by a track etch detector stack. The system was calibrated at high-energy particle accelerators and neutron generators. The developed detectors were investigated by an image analyser, and from the track parameters the linear energy transfer spectra and the absorbed dose were determined (26 microGy/d). Also, the neutron flux was estimated below 5 MeV and found to be 2.4 cm(-2) s(-1) directly from the space. The construction of the stack allowed to investigate the neutrons also from the direction of the carrying satellite, where the flux was found somewhat higher.

  13. Measurements of ultracold neutron upscattering and absorption in polyethylene and vanadium

    CERN Document Server

    Sharapov, E I; Makela, M; Saunders, A; Adamek, Evan R; Bagdasarova, Yelena; Broussard, L J; Cude-Woods, C B; Fellers, Deon E; Geltenbort, Peter; Hasan, S I; Hickerson, K P; Hogan, G; Holley, A T; Liu, Chen-Yu; Mendenhall, M P; Ortiz, J; Pattie, R W; Phillips, D G; Ramsey, J; Salvat, D J; Seestrom, S J; Shaw, E; Sjue, Sky; Sondheim, W E; VornDick, B; Wang, Z; Womack, T L; Young, A R; Zeck, B A

    2013-01-01

    The study of neutron cross sections for elements used as efficient ``absorbers'' of ultracold neutrons (UCN) is crucial for many precision experiments in nuclear and particle physics, cosmology and gravity. In this context, ``absorption'' includes both the capture and upscattering of neutrons to the energies above the UCN energy region. The available data, especially for hydrogen, do not agree between themselves or with the theory. In this report we describe measurements performed at the Los Alamos National Laboratory UCN facility of the UCN upscattering cross sections for vanadium and for hydrogen in CH$_2$ using simultaneous measurements of the radiative capture cross sections for these elements. We measured $\\sigma_{up}=1972\\pm130$ b for hydrogen in CH$_2$, which is below theoretical expectations, and $\\sigma_{up} < 25\\pm9$ b for vanadium, in agreement with the expectation for the neutron heating by thermal excitations in solids.

  14. Optimization of a sup 6 LiF bolometric neutron detector

    CERN Document Server

    Silver, C S; Piccirillo, L; Timbie, P T; Zhou, J W

    2002-01-01

    The optimization of a sup 6 LiF bolometer for neutron spectroscopy applications has been accomplished with a series of 12 different detectors. This type of detector is similar to X-ray bolometers, which have been extensively studied, and the absorber has a high neutron capture cross-section. Each bolometer was irradiated with alpha particles to investigate its response to thermal pulses. The best resolution obtained with this series of bolometers was 39 keV FWHM at 5.3 MeV. One of the bolometers was calibrated with monoenergetic neutrons, and its thermal properties are derived from measurements over a range of temperatures. We discuss the considerations involved in optimizing a sup 6 LiF bolometer for different types of neutron applications.

  15. Neutron capture reactions at DANCE

    Science.gov (United States)

    Bredeweg, T. A.

    2008-05-01

    The Detector for Advanced Neutron Capture Experiments (DANCE) is a 4π BaF2 array consisting of 160 active detector elements. The primary purpose of the array is to perform neutron capture cross section measurements on small (>~100 μg) and/or radioactive (DANCE we have performed neutron capture cross section measurements on a wide array of medium to heavy mass nuclides. Measurements to date include neutron capture cross sections on 241,243Am, neutron capture and neutron-induced fission cross sections and capture-to-fission ratio (α = σγ/σf) for 235U using a new fission-tagging detector as well as neutron capture cross sections for several astrophysics branch-point nuclei. Results from several of these measurements will be presented along with a discussion of additional physics information that can be extracted from the DANCE data.

  16. Nanostructure Neutron Converter Layer Development

    Science.gov (United States)

    Park, Cheol (Inventor); Sauti, Godfrey (Inventor); Kang, Jin Ho (Inventor); Lowther, Sharon E. (Inventor); Thibeault, Sheila A. (Inventor); Bryant, Robert G. (Inventor)

    2016-01-01

    Methods for making a neutron converter layer are provided. The various embodiment methods enable the formation of a single layer neutron converter material. The single layer neutron converter material formed according to the various embodiments may have a high neutron absorption cross section, tailored resistivity providing a good electric field penetration with submicron particles, and a high secondary electron emission coefficient. In an embodiment method a neutron converter layer may be formed by sequential supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In another embodiment method a neutron converter layer may be formed by simultaneous supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In a further embodiment method a neutron converter layer may be formed by in-situ metalized aerogel nanostructure development.

  17. Absorbed fractions for electrons in ellipsoidal volumes

    Science.gov (United States)

    Amato, E.; Lizio, D.; Baldari, S.

    2011-01-01

    We applied a Monte Carlo simulation in Geant4 in order to calculate the absorbed fractions for monoenergetic electrons in the energy interval between 10 keV and 2 MeV, uniformly distributed in ellipsoids made from soft tissue. For each volume, we simulated a spherical shape, four oblate and four prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found, and the dependence of the fit parameters from electron energy is discussed and fitted by proper parametric functions. With the proposed formulation, the absorbed fraction for electrons in the 10-2000 keV energy range can be calculated for all volumes and for every ellipsoidal shape of practical interest. This method can be directly applied to evaluation of the absorbed fraction from the radionuclide emission of monoenergetic electrons, such as Auger or conversion electrons. The average deposited energy per disintegration in the case of extended beta spectra can be evaluated through integration. Two examples of application to a pure beta emitter such as 90Y and to 131I, whose emission include monoenergetic and beta electrons plus gamma photons, are presented. This approach represent a generalization of our previous studies, allowing a comprehensive treatment of absorbed fractions from electron and photon sources uniformly distributed in ellipsoidal volumes of any ellipticity and volume, in the whole range of practical interest for internal dosimetry in nuclear medicine applications, as well as in radiological protection estimations of doses from an internal contamination.

  18. Observation of Neutron Skyshine from an Accelerator Based Neutron Source

    Energy Technology Data Exchange (ETDEWEB)

    Franklyn, C. B. [Radiation Science Department, Necsa, PO Box 582, Pretoria 0001 (South Africa)

    2011-12-13

    A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >10{sup 11} n{center_dot}s{sup -1}. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It is further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine.

  19. Neutron logging tool readings and neutron parameters of formations

    Science.gov (United States)

    Czubek, Jan A.

    1995-03-01

    A case history of the calibration of neutron porosity tools is given in the paper. The calibration of neutron porosity tools is one of the most difficult, complicated, and time consuming tasks in the well logging operations in geophysics. A semi empirical approach to this problem is given in the paper. It is based on the correlation of the tool readings observed in known environments with the apparent neutron parameters sensed by the tools. The apparent neutron parameters are functions of the true neutron parameters of geological formations and of the borehole material, borehole diameter, and the tool position inside the borehole. The true integral neutron transport parameters are obtained by the multigroup diffusion approximation for slowing down of neutrons and by one thermal neutron group for the diffusion. In the latter, the effective neutron temperature is taken into account. The problem of the thermal neutron absorption cross section of rocks is discussed in detail from the point of view of its importance for the well logging results and for the experimental techniques being used.

  20. Induction of chromosomal aberrations in human lymphocytes by fission neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcia Augusta da; Coelho, Paulo Rogerio Pinto; Bartolini, Paolo; Okazaki, Kayo [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil)], e-mail: kokazaki@ipen.br

    2009-07-01

    Chromosome aberrations induced by sparsely ionizing radiation (low-LET) are well known and cytogenetic analyses of irradiated human lymphocytes have been widely applied to biological dosimetry. However, much less is known about chromosome aberrations induced by densely ionizing radiation (high LET), such as that of alpha particles or neutrons. Such particles induce DNA strand breaks, as well as chromosome breakage and rearrangements of high complexity. This damage is more localized and less efficiently repaired than after X- or {gamma}-ray irradiation. This preferential production of complex aberrations by densely ionizing radiation is related to the unique energy deposition patterns, which produces highly localized multiple DNA damage at the chromosomal level. A better knowledge of the interactions between different types of radiation and cellular DNA is of importance, not only from the radiobiological viewpoint but also for dosimetric and therapeutic purposes. The objective of the present study was to analyse the cytogenetic effects of fission neutrons on peripheral blood lymphocytes in order to evaluate structural and numerical aberrations and number of cells in the different mitotic cycles. So, blood samples from five healthy donors, 22-25 years old, of both sexes, were irradiated in the Research Reactor IEA-R1 of our Institute (IPEN/CNEN-SP) with thermal and fast neutrons at doses of 0.2; 0.3; 0.5 and 1.0 Gy. The {gamma} contribution to the total absorbed dose was about 30%. These doses were monitored by thermoluminescent dosemeters: LiF-600 (for neutrons) and LiF-700 (for {gamma}-rays). The data concerning structural aberrations were evaluated with regard to three parameters: percentage of cells with aberrations, number of aberrations/cell and number of dicentric/cell. The cytogenetic results showed an increase in the three parameters after irradiation with neutrons, as a function of radiation dose. Apparently, there was no influence of neutrons on the

  1. Experimental evidence of an incomplete thermalization of the energy in an x-ray microcalorimeter with a TaAu absorber.

    Science.gov (United States)

    Perinati, E; Barbera, M; Varisco, S; Silver, E; Beeman, J; Pigot, C

    2008-05-01

    We have conducted an experimental test at our XACT facility using an x-ray microcalorimeter with TaAu absorber and neutron transmutation doped germanium thermal sensor. The test was aimed at measuring the percentage of energy effectively thermalized after absorption of x-ray photons in superconducting tantalum. Moreover, in general, possible formation of long living quasiparticles implies that by using a superconducting absorber, a fraction of the deposited energy could not be thermalized on the useful time scale of the thermal sensor. To investigate this scenario, we exploited an absorber made of gold, where no energy trapping is expected, with a small piece of superconducting tantalum attached on top. We obtained evidence that the thermalization of photons absorbed in tantalum is delayed by energy trapping from quasiparticles. We compare the experimental results with numerical simulations and derive a value for the intrinsic lifetime of quasiparticles.

  2. Neutron beam design for low intensity neutron and gamma-ray radioscopy using small neutron sources

    CERN Document Server

    Matsumoto, T

    2003-01-01

    Two small neutron sources of sup 2 sup 5 sup 2 Cf and sup 2 sup 4 sup 1 Am-Be radioisotopes were used for design of neutron beams applicable to low intensity neutron and gamma ray radioscopy (LINGR). In the design, Monte Carlo code (MCNP) was employed to generate neutron and gamma ray beams suited to LINGR. With a view to variable neutron spectrum and neutron intensity, various arrangements were first examined, and neutron-filter, gamma-ray shield and beam collimator were verified. Monte Carlo calculations indicated that with a suitable filter-shield-collimator arrangement, thermal neutron beam of 3,900 ncm sup - sup 2 s sup - sup 1 with neutron/gamma ratio of 7x10 sup 7 , and 25 ncm sup - sup 2 s sup - sup 1 with very large neutron/gamma ratio, respectively, could be produced by using sup 2 sup 5 sup 2 Cf(122 mu g) and a sup 2 sup 4 sup 1 Am-Be(37GBq)radioisotopes at the irradiation port of 35 cm from the neutron sources.

  3. Canyon transfer neutron absorber to fissile material ratio analysis. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Clemmons, J.S.

    1994-03-04

    Waste tank fissile material and non-fissile material estimates are used to evaluate criticality safety for the existing sludge inventory and batches of sludge sent to Extended Sludge Processing (ESP). This report documents the weight ratios of several non-fissile waste constituents to fissile waste constituents from canyon reprocessing waste streams. Weight ratios of Fe, Mn, Al, Mi, and U-238 to fissile material are calculated from monthly loss estimates from the F and H Canyon Low Heat Waste (LHW) and High Heat Waste (HHW) streams. The monthly weight ratios for Fe, Mn and U-238 are then compared to calculated minimum safe weight ratios. Documented minimum safe weight ratios for Al and Ni to fissile material are currently not available. Total mass data for the subject sludge constituents is provided along with scatter plots of the monthly weight ratios for each waste stream.

  4. The corrosion resistance and neutron-absorbing properties of coatings based on amorphous alloys

    Science.gov (United States)

    Sevryukov, O. N.; Polyansky, A. A.

    2016-04-01

    The object of the present study was the corrosion-resistant amorphizing alloys with an increased content of boron for cladding the surface of metals, rapidly quenched alloys without boron for protective coatings on a high-boron cladding layer, as well as steel samples with a protective coating with a high content of boron and without boron. The aim of the work is to investigate the corrosion resistance of a coating in water at the temperature of 40 °C in conditions of an open access of oxygen for 1000 h, as well as the features of the microstructure of clad samples before and after the corrosion tests. New data on the corrosion resistance of Cr18Ni10Ti steel samples with a protective layer from a rapidly quenched alloy Ni-19Cr-10Si (in wt.%) on a high-boron coating have been obtained.

  5. Towards 0.1-mm spatial resolution in neutron diffractometry

    CERN Document Server

    Stoica, A D

    2002-01-01

    A design goal for VULCAN, the SNS engineering neutron diffractometer, is to enable spatial mapping with 0.1-mm resolution. Because the targeted applications often involve the use of large samples or special environments, slits cannot be used for this purpose. In this paper, methods to achieve 0.1-mm spatial resolution are outlined. For the incident beam, a new compact focusing device is proposed. The device is made of a stack of bent silicon wafers, each having a reflective multilayer (supermirror) deposited on one side and a neutron-absorbing layer on the other side. The optimal design to minimize the optical spatial aberrations is discussed and Monte Carlo simulation results are presented. For the diffracted beam, imaging devices made from thick packets of diffracting bent silicon wafers (known as Bragg mirrors) could be used. The requirements to achieve sharp imaging together with a large phase-space acceptance window are discussed and preliminary testing results are presented. (orig.)

  6. Peculiarities of neutron waveguides with thin Gd layer

    CERN Document Server

    Khaydukov, Yu; Progliado, V; Ustinov, V; Nikitenko, Yu; Keller, T; Aksenov, V; Keimer, B

    2015-01-01

    Peculiarities of the formation of a neutron enhanced standing wave in the structure with a thin highly absorbing layer of gadolinium are considered in the article. An analogue of the poisoning effect well known in reactor physics was found. The effect is stronger for the Nb/Gd/Nb system. Despite of this effect, for a Nb/Gd bilayer and a Nb/Gd/Nb trilayer placed between Al2O3 substrate and Cu layer, it is shown theoretically and experimentally that one order of magnitude enhancement of neutron density is possible in the vicinity of the Gd layer. This enhancement makes it possible to study domain formation in the Gd layer under transition of the Nb layer(s) into the superconducting state (cryptoferromagnetic phase).

  7. Design of a high-flux epithermal neutron beam using 235U fission plates at the Brookhaven Medical Research Reactor.

    Science.gov (United States)

    Liu, H B; Brugger, R M; Rorer, D C; Tichler, P R; Hu, J P

    1994-10-01

    Beams of epithermal neutrons are being used in the development of boron neutron capture therapy for cancer. This report describes a design study in which 235U fission plates and moderators are used to produce an epithermal neutron beam with higher intensity and better quality than the beam currently in use at the Brookhaven Medical Research Reactor (BMRR). Monte Carlo calculations are used to predict the neutron and gamma fluxes and absorbed doses produced by the proposed design. Neutron flux measurements at the present epithermal treatment facility (ETF) were made to verify and compare with the computed results where feasible. The calculations indicate that an epithermal neutron beam produced by a fission-plate converter could have an epithermal neutron intensity of 1.2 x 10(10) n/cm2.s and a fast neutron dose per epithermal neutron of 2.8 x 10(-11) cGy.cm2/nepi plus being forward directed. This beam would be built into the beam shutter of the ETF at the BMRR. The feasibility of remodeling the facility is discussed.

  8. Neutron Scattering Investigations of Correlated Electron Systems and Neutron Instrumentation

    DEFF Research Database (Denmark)

    Holm, Sonja Lindahl

    are a unique probe for studying the atomic and molecular structure and dynamics of materials. Even though neutrons are very expensive to produce, the advantages neutrons provide overshadow the price. As neutrons interact weakly with materials compared to many other probes, e.g. electrons or photons......, it is possible to make a neutron scattering experiment through sample environment equipment like cryostats or pressure cells. Another advantage of neutron experiments is that the wavelength and energy of the neutron match the inter-atomic distances and basic excitations of solid materials. The scattering cross...... magnetism. This is in contrast to what is observed as the critical temperature is slightly lower for this system compared to other co-doped systems, suggesting that the magnetic and superconducting phases co-exist. A published manuscript describes the study of magnetic and superconducting properties of Ba...

  9. Neutron-gamma competition for $\\beta$-delayed neutron emission

    CERN Document Server

    Mumpower, Matthew; Moller, Peter

    2016-01-01

    We present a coupled Quasi-particle Random Phase Approximation and Hauser-Feshbach (QRPA+HF) model for calculating delayed particle emission. This approach uses microscopic nuclear structure information which starts with Gamow-Teller strength distributions in the daughter nucleus, and then follows the statistical decay until the initial available excitation energy is exhausted. Explicitly included at each particle emission stage is $\\gamma$-ray competition. We explore this model in the context of neutron emission of neutron-rich nuclei and find that neutron-gamma competition can lead to both increases and decreases in neutron emission probabilities, depending on the system considered. A second consequence of this formalism is a prediction of more neutrons on average being emitted after $\\beta$-decay for nuclei near the neutron dripline compared to models that do not consider the statistical decay.

  10. The alanine detector in BNCT dosimetry: Dose response in thermal and epithermal neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, T., E-mail: schmito@uni-mainz.de [Institute for nuclear chemistry, Johannes Gutenberg-University, Mainz D-55128 (Germany); Bassler, N. [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, Aarhus C, Aarhus 8000 (Denmark); Blaickner, M. [AIT Austrian Institute of Technology GmbH, Vienna A-1220 (Austria); Ziegner, M. [AIT Austrian Institute of Technology GmbH, Vienna A-1220, Austria and TU Wien, Vienna University of Technology, Vienna A-1020 (Austria); Hsiao, M. C. [Insitute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Liu, Y. H. [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Koivunoro, H. [Department of Physics, University of Helsinki, POB 64, FI-00014, Finland and HUS Medical Imaging Center, Helsinki University Central Hospital, FI-00029 HUS (Finland); Auterinen, I.; Serén, T.; Kotiluoto, P. [VTT Technical Research Centre of Finland, Espoo (Finland); Palmans, H. [National Physical Laboratory, Acoustics and Ionising Radiation Division, Teddington TW11 0LW, United Kingdom and Medical Physics Group, EBG MedAustron GmbH, Wiener Neustadt A-2700 (Austria); Sharpe, P. [National Physical Laboratory, Acoustics and Ionising Radiation Division, Teddington TW11 0LW (United Kingdom); Langguth, P. [Department of Pharmacy and Toxicology, University of Mainz, Mainz D-55128 (Germany); Hampel, G. [Institut für Kernchemie, Johannes Gutenberg-Universität, Mainz D-55128 (Germany)

    2015-01-15

    Purpose: The response of alanine solid state dosimeters to ionizing radiation strongly depends on particle type and energy. Due to nuclear interactions, neutron fields usually also consist of secondary particles such as photons and protons of diverse energies. Various experiments have been carried out in three different neutron beams to explore the alanine dose response behavior and to validate model predictions. Additionally, application in medical neutron fields for boron neutron capture therapy is discussed. Methods: Alanine detectors have been irradiated in the thermal neutron field of the research reactor TRIGA Mainz, Germany, in five experimental conditions, generating different secondary particle spectra. Further irradiations have been made in the epithermal neutron beams at the research reactors FiR 1 in Helsinki, Finland, and Tsing Hua open pool reactor in HsinChu, Taiwan ROC. Readout has been performed with electron spin resonance spectrometry with reference to an absorbed dose standard in a {sup 60}Co gamma ray beam. Absorbed doses and dose components have been calculated using the Monte Carlo codes FLUKA and MCNP. The relative effectiveness (RE), linking absorbed dose and detector response, has been calculated using the Hansen and Olsen alanine response model. Results: The measured dose response of the alanine detector in the different experiments has been evaluated and compared to model predictions. Therefore, a relative effectiveness has been calculated for each dose component, accounting for its dependence on particle type and energy. Agreement within 5% between model and measurement has been achieved for most irradiated detectors. Significant differences have been observed in response behavior between thermal and epithermal neutron fields, especially regarding dose composition and depth dose curves. The calculated dose components could be verified with the experimental results in the different primary and secondary particle fields. Conclusions: The

  11. Effect of the bio-absorbent on the microwave absorption property of the flaky CIPs/rubber absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Yang; Xu, Yonggang, E-mail: xuyonggang221@163.com; Cai, Jun; Yuan, Liming; Zhang, Deyuan

    2015-09-01

    Microwave absorbing composites filled with flaky carbonyl iron particles (CIPs) and the bio-absorbent were prepared by using a two-roll mixer and a vulcanizing machine. The electromagnetic (EM) parameters were measured by a vector network analyzer and the reflection loss (RL) was measured by the arch method in the frequency range of 1–4 GHz. The uniform dispersion of the absorbents was verified by comparing the calculated RL with the measured one. The results confirm that as the bio-absorbent was added, the permittivity was increased due to the volume content of absorbents, and the permeability was enlarged owing to the volume content of CIPs and interactions between the two absorbents. The composite filled with bio-absorbents achieved an excellent absorption property at a thickness of 1 mm (minimum RL reaches −7.8 dB), and as the RL was less than −10 dB the absorption band was widest (2.1–3.8 GHz) at a thickness of 2 mm. Therefore, the bio-absorbent is a promising additive candidate on fabricating microwave absorbing composites with a thinner thickness and wider absorption band. - Graphical abstract: Morphology of composites filled with flaky CIPs and the bio-absorbent. The enhancement of bio-absorbent on the electromagnetic absorption property of composites filled with flaky carbonyl iron particles (CIPs) is attributed to the interaction of the two absorbents. The volume content of the FCMPs with the larger shape CIPs play an important role in this effects, the composites filled with irons and bio-absorbents can achieve wider-band and thinner-thickness absorbing materials. - Highlights: • Absorbers filled with bio-absorbents and CIPs was fabricated. • Bio-absorbents enhanced the permittivity and permeability of the composites. • The absorbent interactions play a key role in the enhancement mechanism. • Bio-absorbents enhanced the composite RL in 1–4 GHz.

  12. Herschel and Spitzer observations of slowly rotating, nearby isolated neutron stars

    CERN Document Server

    Posselt, B; Popov, S B; Wachter, S

    2014-01-01

    Supernova fallback disks around neutron stars have been discussed to influence the evolution of the diverse neutron star populations. Slowly rotating neutron stars are most promising to find such disks. Searching for the cold and warm debris of old fallback disks, we carried out Herschel PACS (70 $\\mu$m, 160 $\\mu$m) and Spitzer IRAC (3.6 $\\mu$m, 4.5 $\\mu$m) observations of eight slowly rotating ($P\\approx 3 - 11$ s) nearby ($5\\sigma$) at locations consistent with the positions of the neutron stars RX J0806.4-4123 and RX J2143.0+0654. No other significant infrared emission was detected from the eight neutron stars. We estimate probabilities of 63%, 33% and 3% that, respectively, none, one, or both Herschel PACS 160 $\\mu$m detections are unrelated excess sources due to background source confusion or an interstellar cirrus. If the 160 $\\mu$m emission is indeed related to cold (10 K to 22 K) dust around the neutron stars, this dust is absorbing and re-emitting $\\sim 10$% to $\\sim 20$% of the neutron stars' X-rays...

  13. Beams of gravitationally bound ultracold neutrons in rough waveguides

    Science.gov (United States)

    Escobar, M.; Meyerovich, A. E.

    2011-03-01

    We investigate the propagation of ultracold neutrons through a rough waveguide in conjunction with recent experiments in which the ultracold neutrons were beamed between a perfect mirror and a rough scatterer and absorber. The main goal is to find a way to resolve the lowest gravitationally quantized discrete states in the peV range. We compare the neutron count for various types of mirrors with Gaussian, power-law, and exponential correlation functions of surface inhomogeneities. The main conclusion is that all the information about inhomogeneities, including their amplitude, correlation radius, and the rate of decay of the correlation function, enter the exit neutron count via just a single constant Φ, which effectively renormalizes the amplitude of roughness. To observe well-defined quantum steps, one should have an experimental setup with Φ>40. For a wide variety of correlation functions, the constant Φ is proportional to the square of the amplitude of the surface roughness and is inversely proportional to the square root of the correlation radius. The strong dependence of Φ on roughness parameters and the shape of the correlation function opens a novel way for improving the resolution of gravitationally bound states by optimizing the roughness pattern without reverting to an undesirable strong roughness. We discuss how to optimize the scatterer and absorber by first generating numerically the desired roughness profile and then transferring it to the mirror. We also study the effect of beam preparation on the initial occupancies of gravitational states before the beam enters the waveguide. It turns out that there are simple ways to manipulate the beam in front of the waveguide that can help to resolve the gravitationally bound quantum states. Our results are in good agreement with available experimental data.

  14. Optimization of sound absorbing performance for gradient multi-layer-assembled sintered fibrous absorbers

    Science.gov (United States)

    Zhang, Bo; Zhang, Weiyong; Zhu, Jian

    2012-04-01

    The transfer matrix method, based on plane wave theory, of multi-layer equivalent fluid is employed to evaluate the sound absorbing properties of two-layer-assembled and three-layer-assembled sintered fibrous sheets (generally regarded as a kind of compound absorber or structures). Two objective functions which are more suitable for the optimization of sound absorption properties of multi-layer absorbers within the wider frequency ranges are developed and the optimized results of using two objective functions are also compared with each other. It is found that using the two objective functions, especially the second one, may be more helpful to exert the sound absorbing properties of absorbers at lower frequencies to the best of their abilities. Then the calculation and optimization of sound absorption properties of multi-layer-assembled structures are performed by developing a simulated annealing genetic arithmetic program and using above-mentioned objective functions. Finally, based on the optimization in this work the thoughts of the gradient design over the acoustic parameters- the porosity, the tortuosity, the viscous and thermal characteristic lengths and the thickness of each samples- of porous metals are put forth and thereby some useful design criteria upon the acoustic parameters of each layer of porous fibrous metals are given while applying the multi-layer-assembled compound absorbers in noise control engineering.

  15. Neutronics Assessments for a RIA Fragmentation Line Beam Dump Concept

    CERN Document Server

    Boles, Jason; Reyes, Susana; Stein, Werner

    2005-01-01

    Heavy ion and radiation transport calculations are in progress for conceptual beam dump designs for the fragmentation line of the proposed Rare Isotope Accelerator (RIA). Using the computer code PHITS, a preliminary design of a motor-driven rotating wheel beam dump and adjacent downstream multipole has been modeled. Selected results of these calculations are given, including neutron and proton flux in the wheel, absorbed dose and displacements per atom in the hub materials, and heating from prompt radiation and from decay heat in the multipole.

  16. Are geological media homogeneous or heterogeneous for neutron investigations?

    Science.gov (United States)

    Woźnicka, U; Drozdowicz, K; Gabańska, B; Krynicka, E; Igielski, A

    2003-01-01

    The thermal neutron absorption cross section of a heterogeneous material is lower than that of the corresponding homogeneous one which contains the same components. When rock materials are investigated the sample usually contains grains which create heterogeneity. The heterogeneity effect depends on the mass contribution of highly and low-absorbing centers, on the ratio of their absorption cross sections, and on their sizes. An influence of the granulation of silicon and diabase samples on the absorption cross section measured with Czubek's method has been experimentally investigated. A 20% underestimation of the absorption cross section has been observed for diabase grains of sizes from 6.3 to 12.8 mm.

  17. Fast neutron imaging device and method

    Science.gov (United States)

    Popov, Vladimir; Degtiarenko, Pavel; Musatov, Igor V.

    2014-02-11

    A fast neutron imaging apparatus and method of constructing fast neutron radiography images, the apparatus including a neutron source and a detector that provides event-by-event acquisition of position and energy deposition, and optionally timing and pulse shape for each individual neutron event detected by the detector. The method for constructing fast neutron radiography images utilizes the apparatus of the invention.

  18. Progress of Neutron Bubble Detectors in CIAE

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Neutron bubble detector is the only personal neutron dosimeter which has adequate neutronsensitivity to meet the implications of the ICRP 60 recommendations for neutron dosimetry. It canmonitor the wide range of neutron energy, for example 100 eV to 10 MeV And it becomes a significanttool for neutron dose monitoring at the environment of nuclear energy.

  19. Measurement of neutron scattering lengths using neutron interferometry

    Science.gov (United States)

    Shahi, Chandra B.

    This thesis describes the details on building a new Neutron Interferometry and Optics Facility (NIOFa), the measurement of the incoherent neutron scattering length bi of 3He, and the measurement of the coherent neutron scattering length bc of 4He at National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR). A new monochromatic beamline and facility has been installed at the NCNR devoted to neutron interferometry in the research areas of spin control, spin manipulation, quantum mechanics, quantum information science, spintronics, and material science. This facility is possible in part because of advances in decoherence free subspace interferometer designs that have demonstrated consistent contrast in the presence of vibrational noise; a major environmental constraint that has prevented neutron interferometry from being applied at other neutron facilities. This new facility, NIOFa, is located in the guide hall of the NCNR upstream of the existing Neutron Interferometry and Optics Facility (NIOF) and has several advantages over the NIOF including higher incident flux, better neutron polarization, and increased accessibility. The measurement of the incoherent neutron scattering length bi of 3He was done using a (220) single silicon crystal skew symmetric interferometer. This experiment requires both a polarized beam and a polarized target. We report bi = -2.35 +/- 0.014 (stat.) +/- 0.014 (syst.). This experiment is a revision of the previous experiment which was done in 2008, and partially explains the non-zero phase shift seen in 2008 experiment even if target cell was completely unpolarized. The measurement of the coherent neutron scattering length b c of the 4He was done using a (111) single silicon crystal interferometer. The neutron interferometry and optics facility at NIST had been used previously to determine the coherent scattering lengths for n- 1H, n-2H, and n-3He to less than 1% relative uncertainty. We report bc of the 4He

  20. A sound absorbing metasurface with coupled resonators

    Science.gov (United States)

    Li, Junfei; Wang, Wenqi; Xie, Yangbo; Popa, Bogdan-Ioan; Cummer, Steven A.

    2016-08-01

    An impedance matched surface is able, in principle, to totally absorb the incident sound and yield no reflection, and this is desired in many acoustic applications. Here we demonstrate a design of impedance matched sound absorbing surface with a simple construction. By coupling different resonators and generating a hybrid resonance mode, we designed and fabricated a metasurface that is impedance-matched to airborne sound at tunable frequencies with subwavelength scale unit cells. With careful design of the coupled resonators, over 99% energy absorption at central frequency of 511 Hz with a 50% absorption bandwidth of 140 Hz is achieved experimentally. The proposed design can be easily fabricated, and is mechanically stable. The proposed metasurface can be used in many sound absorption applications such as loudspeaker design and architectural acoustics.

  1. Absorbing angles, Steiner minimal trees, and antipodality

    CERN Document Server

    Martini, Horst; de Wet, P Oloff; 10.1007/s10957-009-9552-1

    2011-01-01

    We give a new proof that a star $\\{op_i:i=1,...,k\\}$ in a normed plane is a Steiner minimal tree of its vertices $\\{o,p_1,...,p_k\\}$ if and only if all angles formed by the edges at o are absorbing [Swanepoel, Networks \\textbf{36} (2000), 104--113]. The proof is more conceptual and simpler than the original one. We also find a new sufficient condition for higher-dimensional normed spaces to share this characterization. In particular, a star $\\{op_i: i=1,...,k\\}$ in any CL-space is a Steiner minimal tree of its vertices $\\{o,p_1,...,p_k\\}$ if and only if all angles are absorbing, which in turn holds if and only if all distances between the normalizations $\\frac{1}{\\|p_i\\|}p_i$ equal 2. CL-spaces include the mixed $\\ell_1$ and $\\ell_\\infty$ sum of finitely many copies of $R^1$.

  2. Absorbing Software Testing into the Scrum Method

    Science.gov (United States)

    Tuomikoski, Janne; Tervonen, Ilkka

    In this paper we study, how to absorb software testing into the Scrum method. We conducted the research as an action research during the years 2007-2008 with three iterations. The result showed that testing can and even should be absorbed to the Scrum method. The testing team was merged into the Scrum teams. The teams can now deliver better working software in a shorter time, because testing keeps track of the progress of the development. Also the team spirit is higher, because the Scrum team members are committed to the same goal. The biggest change from test manager’s point of view was the organized Product Owner Team. Test manager don’t have testing team anymore, and in the future all the testing tasks have to be assigned through the Product Backlog.

  3. Use of Wedge Absorbers in MICE

    Energy Technology Data Exchange (ETDEWEB)

    Neuffer, D. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Summers, D. [Univ. of Mississippi, Oxford, MS (United States); Mohayai, T. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); IIT, Chicago, IL (United States); Snopok, P. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); IIT, Chicago, IL (United States); Rogers, C. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL)

    2017-03-01

    Wedge absorbers are needed to obtain longitudinal cooling in ionization cooling. They also can be used to obtain emittance exchanges between longitudinal and transverse phase space. There can be large exchanges in emittance, even with single wedges. In the present note we explore the use of wedge absorbers in the MICE experiment to obtain transverse–longitudinal emittance exchanges within present and future operational conditions. The same wedge can be used to explore “direct” and “reverse” emittance exchange dynamics, where direct indicates a configuration that reduces momentum spread and reverse is a configuration that increases momentum spread. Analytical estimated and ICOOL and G4BeamLine simulations of the exchanges at MICE parameters are presented. Large exchanges can be obtained in both reverse and direct configurations.

  4. Neutron electric polarizability

    CERN Document Server

    Alexandru, Andrei

    2009-01-01

    We use the background field method to extract the "connected" piece of the neutron electric polarizability. We present results for quenched simulations using both clover and Wilson fermions and discuss our experience in extracting the mass shifts and the challenges we encountered when we lowered the quark mass. For the neutron we find that as the pion mass is lowered below $500\\MeV$, the polarizability starts rising in agreement with predictions from chiral perturbation theory. For our lowest pion mass, $m_\\pi=320\\MeV$, we find that $\\alpha_n = 3.8(1.3)\\times 10^{-4}\\fm^3$, which is still only one third of the experimental value. We also present results for the neutral pion; we find that its polarizability turns negative for pion masses smaller than $500\\MeV$ which is puzzling.

  5. Neutron beam measurement dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Amaro, C.R. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1995-11-01

    This report describes animal dosimetry studies and phantom measurements. During 1994, 12 dogs were irradiated at BMRR as part of a 4 fraction dose tolerance study. The animals were first infused with BSH and irradiated daily for 4 consecutive days. BNL irradiated 2 beagles as part of their dose tolerance study using BPA fructose. In addition, a dog at WSU was irradiated at BMRR after an infusion of BPA fructose. During 1994, the INEL BNCT dosimetry team measured neutron flux and gamma dose profiles in two phantoms exposed to the epithermal neutron beam at the BMRR. These measurements were performed as a preparatory step to the commencement of human clinical trials in progress at the BMRR.

  6. Neutron Scattering Stiudies

    Energy Technology Data Exchange (ETDEWEB)

    Kegel, Gunter H.R.; Egan, James J

    2007-04-18

    This project covers four principal areas of research: Elastic and inelastic neutron scattering studies in odd-A terbium, thulium and other highly deformed nuclei near A=160 with special regard to interband transitions and to the investigation of the direct-interaction versus the compound-nucleus excitation process in these nuclei. Examination of new, fast photomultiplier tubes suitable for use in a miniaturized neutron-time-of-flight spectrometer. Measurement of certain inelastic cross sections of 238U. Determination of the multiplicity of prompt fission gamma rays in even-A fissile actinides. Energies and mean lives of fission isomers produced by fast fission of even-Z, even-A actinides. Study of the mean life of 7Be in different host matrices and its possible astro-physical significance.

  7. Neutrons from Antiproton Irradiation

    DEFF Research Database (Denmark)

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

    Background: Radiotherapy with Antiprotons is currently investigated by the AD-4/ACE collaboration. The hypothesis is that the additional energy released from the antiprotons annihilating at the target nuclei can enable a reduced dose in the entry channel of the primary beam. Furthermore an enhanced...... relative biological effect (RBE) has already been beam measured in spread out Bragg peaks of antiprotons, relative to that found in the plateau region. However, the antiproton annihilation process is associated with a substantial release of secondary particles which contribute to the dose outside...... the neutron spectrum. Additionally, we used a cylindrical polystyrene loaded with several pairs of thermoluminescent detectors containing Lithium-6 and Lithium-7, which effectively detects thermalized neutrons. The obtained results are compared with FLUKA imulations. Results: The results obtained...

  8. The LTS{sub N} method used for the determination of parameters in heterogeneous shielding for neutrons and photons; O uso do metodo LTS{sub N} na obtencao de parametros de blindagens multiplas para neutrons e fotons

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Volnei [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Dept. de Engenharia Nuclear; Francio, Laci Maria; Brigoni, Justina Ines Fronza [Universidade de Caxias do Sul, RS (Brazil). Dept. de Ciencias Exatas e da Natureza

    2002-07-01

    In this work the LTS{sub N} methodology is used for determination of the radiation flux distribution into the homogeneous and heterogeneous shielding, using the multigroup model in energy, for photons and neutrons. Numerical results for emergent flux, absorbed dose rates and buildup factor are reported. (author)

  9. Oxygen absorbers in food preservation: a review

    OpenAIRE

    Cichello, Simon Angelo

    2014-01-01

    The preservation of packaged food against oxidative degradation is essential to establish and improve food shelf life, customer acceptability, and increase food security. Oxygen absorbers have an important role in the removal of dissolved oxygen, preserving the colour, texture and aroma of different food products, and importantly inhibition of food spoilage microbes. Active packaging technology in food preservation has improved over decades mostly due to the sealing of foods in oxygen imperme...

  10. 2D Saturable Absorbers for Fibre Lasers

    Directory of Open Access Journals (Sweden)

    Robert I. Woodward

    2015-11-01

    Full Text Available Two-dimensional (2D nanomaterials are an emergent and promising platform for future photonic and optoelectronic applications. Here, we review recent progress demonstrating the application of 2D nanomaterials as versatile, wideband saturable absorbers for Q-switching and mode-locking fibre lasers. We focus specifically on the family of few-layer transition metal dichalcogenides, including MoS2, MoSe2 and WS2.

  11. VUV Absorbing Vapours in n-Perfluorocarbons

    CERN Document Server

    Albrecht, E; Bellunato, T F; Bressan, A; Dalla Torre, S; D'Ambrosio, C; Davenport, M; Dragicevic, M; Duarte-Pinto, S; Fauland, P; Ilie, S; Lenzen, Georg; Pagano, P; Piedigrossi, D; Tessarotto, F; Ullaland, O

    2003-01-01

    The optical transparency of perfluorocarbons used as Cherenkov media is of prime importance to many Ring Imaging Cherenkov detectors. We will in this paper show that the main photon absorbers in these fluids are hydrocarbons with double or triple bonds. We will moreover discuss a process which can eliminate these pollutants and restore the intrinsic excellent optical transparency of these fluids in the VUV range.

  12. Preparation of perlite-based carbon dioxide absorbent.

    Science.gov (United States)

    He, H; Wu, L; Zhu, J; Yu, B

    1994-02-01

    A new highly efficient carbon dioxide absorbent consisting of sodium hydroxide, expanded perlite and acid-base indicator was prepared. The absorption efficiency, absorption capacity, flow resistance and color indication for the absorbent were tested and compared with some commercial products. The absorbent can reduce the carbon dioxide content in gases to 3.3 ppb (v/v) and absorbs not less than 35% of its weight of carbon dioxide. Besides its large capacity and sharp color indication, the absorbent has an outstanding advantage of small flow resistance in comparison with other commercial carbon dioxide absorbents. Applications in gas analysis and purification were also investigated.

  13. Neutron Transport Simulations for NIST Neutron Lifetime Experiment

    Science.gov (United States)

    Li, Fangchen; BL2 Collaboration Collaboration

    2016-09-01

    Neutrons in stable nuclei can exist forever; a free neutron lasts for about 15 minutes on average before it beta decays to a proton, an electron, and an antineutrino. Precision measurements of the neutron lifetime test the validity of weak interaction theory and provide input into the theory of the evolution of light elements in the early universe. There are two predominant ways of measuring the neutron lifetime: the bottle method and the beam method. The bottle method measures decays of ultracold neutrons that are stored in a bottle. The beam method measures decay protons in a beam of cold neutrons of known flux. An improved beam experiment is being prepared at the National Institute of Science and Technology (Gaithersburg, MD) with the goal of reducing statistical and systematic uncertainties to the level of 1 s. The purpose of my studies was to develop computer simulations of neutron transport to determine the beam collimation and study the neutron distribution's effect on systematic effects for the experiment, such as the solid angle of the neutron flux monitor. The motivation for the experiment and the results of this work will be presented. This work was supported, in part, by a Grant to Gettysburg College from the Howard Hughes Medical Institute through the Precollege and Undergraduate Science Education Program.

  14. High-resolution neutron microtomography with noiseless neutron counting detector

    Energy Technology Data Exchange (ETDEWEB)

    Tremsin, A.S., E-mail: ast@ssl.berkeley.edu [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); McPhate, J.B.; Vallerga, J.V.; Siegmund, O.H.W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Feller, W.B. [Nova Scientific Inc., 10 Picker Road, Sturbridge, MA 01566 (United States); Lehmann, E. [Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Butler, L.G. [Louisiana State University, Baton Rouge, LA 70803 (United States); Dawson, M. [Helmholtz Centre Berlin for Materials and Energy (Germany)

    2011-10-01

    The improved collimation and intensity of thermal and cold neutron beamlines combined with recent advances in neutron imaging devices enable high-resolution neutron radiography and microtomography, which can provide information on the internal structure of objects not achievable with conventional X-ray imaging techniques. Neutron detection efficiency, spatial and temporal resolution (important for the studies of dynamic processes) and low background count rate are among the crucial parameters defining the quality of radiographic images and tomographic reconstructions. The unique capabilities of neutron counting detectors with neutron-sensitive microchannel plates (MCPs) and with Timepix CMOS readouts providing high neutron detection efficiency ({approx}70% for cold neutrons), spatial resolutions ranging from 15 to 55 {mu}m and a temporal resolution of {approx}1 {mu}s-combined with the virtual absence of readout noise-make these devices very attractive for high-resolution microtomography. In this paper we demonstrate the capabilities of an MCP-Timepix detection system applied to microtomographic imaging, performed at the ICON cold neutron facility of the Paul Scherrer Institute. The high resolution and the absence of readout noise enable accurate reconstruction of texture in a relatively opaque wood sample, differentiation of internal tissues of a fly and imaging of individual {approx}400 {mu}m grains in an organic powder encapsulated in a {approx}700 {mu}m thick metal casing.

  15. Neutrons in the moon. [neutron flux and production rate calculations

    Science.gov (United States)

    Kornblum, J. J.; Fireman, E. L.; Levine, M.; Aronson, A.

    1973-01-01

    Neutron fluxes for energies between 15 MeV and thermal at depths of 0 to 300 g/sq cm in the moon are calculated by the discrete ordinate mathod with the ANISN code. With the energy spectrum of Lingenfelter et al. (1972). A total neutron-production rate for the moon of 26 plus or minus neutrons/sq cm sec is determined from the Ar-37 activity measurements in the Apollo 16 drill string, which are found to have a depth dependence in accordance with a neutron source function that decreases exponentially with an attenuation length of 155 g/sq cm.

  16. Are there good probes for the di-neutron correlation in light neutron-rich nuclei?

    CERN Document Server

    Hagino, K

    2015-01-01

    The di-neutron correlation is a spatial correlation with which two valence neutrons are located at a similar position inside a nucleus. We discuss possible experimental probes for the di-neutron correlation. This includes the Coulomb breakup and the pair transfer reactions of neutron-rich nuclei, and the direct two-neutron decays of nuclei beyond the neutron drip-line.

  17. Neutrons are flying

    CERN Multimedia

    2000-01-01

    View of the n_TOF tube with members of the design and construction team of the facility(from left to right: R. Magnin/LHC, E. Radermacher/EP, P. Cennini/EP and R. Cappi/PS). A new experimental facility was inaugurated at CERN on Wednesday 8 November. The neutron Time Of Flight (n_TOF) facility received its first protons from the PS at 10:55. With an intensity of 1 x 1011 protons per cycle on the n_TOF target, an intense neutron beam has been produced at CERN for the first time, opening the door to many new avenues of research including, for example, neutron induced cross-section measurements. The facility is an offspring of the work by Carlo Rubbia and his group on the novel idea of an Energy Amplifier. The basic idea was successfully tested at the PS with the FEAT experiment and later with the TARC experiment, where the feasibility of transmutation of long-lived products by Adiabatic Resonance Crossing (ARC) was confirmed. This led to the possibility of radio-isotope production for medical applications, fo...

  18. Neutron instrumentation for biology

    Energy Technology Data Exchange (ETDEWEB)

    Mason, S.A. [Institut Laue-Langevin, Grenoble (France)

    1994-12-31

    In the October 1994 round of proposals at the ILL, the external biology review sub- committee was asked to allocate neutron beam time to a wide range of experiments, on almost half the total number of scheduled neutron instruments: on 3 diffractometers, on 3 small angle scattering instruments, and on some 6 inelastic scattering spectrometers. In the 3.5 years since the temporary reactor shutdown, the ILL`s management structure has been optimized, budgets and staff have been trimmed, the ILL reactor has been re-built, and many of the instruments up-graded, many powerful (mainly Unix) workstations have been introduced, and the neighboring European Synchrotron Radiation Facility has established itself as the leading synchrotron radiation source and has started its official user program. The ILL reactor remains the world`s most intense dedicated neutron source. In this challenging context, it is of interest to review briefly the park of ILL instruments used to study the structure and energetics of small and large biological systems. A brief summary will be made of each class of experiments actually proposed in the latest ILL proposal round.

  19. Neutron dosimetry using proportional counters with tissue equivalent walls; Dosimetrie des neutrons au moyen de compteurs proportionnels a paroi equivalente aux tissus

    Energy Technology Data Exchange (ETDEWEB)

    Kerviller, H. de [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    The author reminds the calculation method of the neutron absorbed dose in a material and deduce of it the conditions what this material have to fill to be equivalent to biological tissues. Various proportional counters are mode with walls in new tissue equivalent material and filled with various gases. The multiplication factor and neutron energy response of these counters are investigated and compared with those obtained with ethylene lined polyethylene counters. The conditions of working of such proportional counters for neutron dosimetry in energy range 10{sup -2} to 15 MeV are specified. (author) [French] L'auteur rappelle la methode de calcul de la dose absorbee due aux neutrons dans un materiau et en deduit les conditions que dolt remplir ce materiau pour titre equivalent aux tissus biologiques. Divers compteurs proportionnels sont realises avec des parois en nouveau materiau equivalent aux tissus et remplis de divers gaz. Les coefficients de multiplication et la reponse en fonction de l'energie des neutrons sont etudies et compares avec ceux de compteurs a paroi de polyethylene et remplis d'ethylene, Les conditions de fonctionnement de tels compteurs proportionnels pour la dosimetrie des neutrons d'energie 10{sup -2} a 15 MeV sont precisees. (auteur)

  20. Exploration of Adiabatic Resonance Crossing Through Neutron Activator Design for Thermal and Epithermal Neutron Formation in (99)Mo Production and BNCT Applications.

    Science.gov (United States)

    Khorshidi, Abdollah

    2015-10-01

    A feasibility study was performed to design thermal and epithermal neutron sources for radioisotope production and boron neutron capture therapy (BNCT) by moderating fast neutrons. The neutrons were emitted from the reaction between (9)Be, (181)Ta, and (184)W targets and 30 MeV protons accelerated by a small cyclotron at 300 μA. In this study, the adiabatic resonance crossing (ARC) method was investigated by means of (207)Pb and (208)Pb moderators, graphite reflector, and boron absorber around the moderator region. Thermal/epithermal flux, energy, and cross section of accumulated neutrons in the activator were examined through diverse thicknesses of the specified regions. Simulation results revealed that the (181)Ta target had the highest neutron yield, and also tungsten was found to have the highest values in both surface and volumetric flux ratio. Transmutation in the (98)Mo sample through radiative capture was investigated for the natural lead moderator. When the sample radial distance from the target was increased inside the graphite region, the production yield had the greatest value of activity. The potential of the ARC method is a replacement or complements the current reactor-based supply sources of BNCT purposes.

  1. Gamma/neutron dose evaluation using Fricke gel and alanine gel dosimeters to be applied in boron neutron capture therapy.

    Science.gov (United States)

    Mangueira, T F; Silva, C F; Coelho, P R P; Campos, L L

    2010-01-01

    Gel dosimetry has been studied mainly for medical applications. The radiation induced ferric ions concentration can be measured by different techniques to be related with the absorbed dose. Aiming to assess gamma/thermal neutrons dose from research reactors, Fricke gel and alanine gel solutions produced at IPEN using 300 bloom gelatin were mixed with Na(2)B(4)O(7) salt, and the mixtures were irradiated at the beam hole #3 of the IEA-R1 research reactor, (BH#3) adapted to BNCT studies, and the dose-response was evaluated using spectrophotometry technique.

  2. Euratom Neutron Radiography Working Group

    DEFF Research Database (Denmark)

    Domanus, Joseph Czeslaw

    1986-01-01

    In 1979 a Neutron Radiography Working Group (NRWG) was constituted within Buratom with the participation of all centers within the European Community at which neutron facilities were available. The main purpose of NRWG was to standardize methods and procedures used in neutron radiography of nuclear...... reactor fuel as well as establish standards for radiographic image quality of neutron radiographs. The NRWG meets once a year in each of the neutron radiography centers to review the progress made and draw plans for the future. Besides, ad-hoc sub-groups or. different topics within the field of neutron...... radiography are constituted. This paper reviews the activities and achievements of the NRWG and its sub-groups....

  3. Neutron background estimates in GESA

    Directory of Open Access Journals (Sweden)

    Fernandes A.C.

    2014-01-01

    Full Text Available The SIMPLE project looks for nuclear recoil events generated by rare dark matter scattering interactions. Nuclear recoils are also produced by more prevalent cosmogenic neutron interactions. While the rock overburden shields against (μ,n neutrons to below 10−8 cm−2 s−1, it itself contributes via radio-impurities. Additional shielding of these is similar, both suppressing and contributing neutrons. We report on the Monte Carlo (MCNP estimation of the on-detector neutron backgrounds for the SIMPLE experiment located in the GESA facility of the Laboratoire Souterrain à Bas Bruit, and its use in defining additional shielding for measurements which have led to a reduction in the extrinsic neutron background to ∼ 5 × 10−3 evts/kgd. The calculated event rate induced by the neutron background is ∼ 0,3 evts/kgd, with a dominant contribution from the detector container.

  4. Effects of dose and dose protraction on embryotoxicity of 14.1 MeV neutron irradiation in rats

    Energy Technology Data Exchange (ETDEWEB)

    Beckman, D.A.; Buck, S.J. [Alfred I. duPont Institute, Wilmington, DE (United States)]|[Thomas Jefferson Univ., Philadelphia, PA (United States); Solomon, H.M. [SmithKline and Beecham Pharmaceuticals, King of Prussia, PA (United States); Gorson, R.O. [Thomas Jefferson Univ., Philadelphia, PA (United States); Mills, R.E. [Brookhaven National Lab., Upton, NY (United States); Brent, R.L. [Alfred I. duPont Institute, Wilmington, DE (United States)]|[Thomas Jefferson Univ., Philadelphia, PA (United States)

    1994-06-01

    The embryotoxic effects of neutron radiation on rodent embryos are documented, but there is disagreement about the dose-response relationship and the impact of protracting the dose. Pregnant rats were exposed to total absorbed doses of 0.15 to 1.50 Gy 14.1 MeV neutrons on day 9.5 after conception, coincident with the most sensitive stage of embryonic development for the induction of major congenital malformations. In general terms, the incidence of embryotoxic effects increased with increasing total absorbed dose. However, the dose-response relationship differed depending on the parameter of embryotoxicity chosen, namely, intrauterine death, malformations or very low body weight. In a second study, embryos were exposed to a single embryotoxic absorbed dose (0.75 Gy) administered at a range of dose rates, from 0.10 to 0.50 Gy/h. The results offer no evidence that protraction of this selected dose significantly increased or decreased the incidence or pattern of embryotoxicity of the neutron exposure used in this study. The results do not support the hypothesis of a linear dose-response relationship for the effects of prenatal neutron irradiation that contribute to embryotoxicity for total absorbed doses of 0.15 to 1.50 Gy. 23 refs., 8 tabs.

  5. Neutron Imaging by Boric Acid

    CERN Document Server

    Cardone, Fabio; Perconti, Walter; Petrucci, Andrea; Rosada, Alberto

    2013-01-01

    In this paper a new type of passive neutron detector based on the already existing one, CR39, is described. Its operation was verified by three different neutron sources: an Americium-Beryllium (Am241-Be) source; a TRIGA type nuclear reactor; and a fast neutron reactor called TAPIRO. The obtained results, reported here, positively confirm its operation and the accountability of the new developed detecting technique.

  6. Study of the relative dose-response of BANG-3® polymer gel dosimeters in epithermal neutron irradiation

    Science.gov (United States)

    Uusi-Simola, J.; Savolainen, S.; Kangasmäki, A.; Heikkinen, S.; Perkiö, J.; Abo Ramadan, U.; Seppälä, T.; Karila, J.; Serén, T.; Kotiluoto, P.; Sorvari, P.; Auterinen, I.

    2003-09-01

    Polymer gels have been reported as a new, potential tool for dosimetry in mixed neutron-gamma radiation fields. In this work, BANG-3 (MGS Research Inc.) gel vials from three production batches were irradiated with 6 MV photons of a Varian Clinac 2100 C linear accelerator and with the epithermal neutron beam of the Finnish boron neutron capture therapy (BNCT) facility at the FiR 1 nuclear reactor. The gel is tissue equivalent in main elemental composition and density and its T2 relaxation time is dependent on the absorbed dose. The T2 relaxation time map of the irradiated gel vials was measured with a 1.5 T magnetic resonance (MR) scanner using spin echo sequence. The absorbed doses of neutron irradiation were calculated using DORT computer code, and the accuracy of the calculational model was verified by measuring gamma ray dose rate with thermoluminescent dosimeters and 55Mn(n,gamma) activation reaction rate with activation detectors. The response of the BANG-3 gel dosimeter for total absorbed dose in the neutron irradiation was linear, and the magnitude of the response relative to the response in the photon irradiation was observed to vary between different gel batches. The results support the potential of polymer gels in BNCT dosimetry, especially for the verification of two- or three-dimensional dose distributions.

  7. Estimate of the damage in organs induced by neutrons in three-dimensional conformal radiotherapy; Estimacion del dano en organos inducido por neutrones en radioterapia conformada en 3D

    Energy Technology Data Exchange (ETDEWEB)

    Benites R, J. L. [Centro Estatal de Cancerologia de Nayarit, Servicio de Seguridad Radiologica, Calzada de la Cruz 118 sur, 63000 Tepic, Nayarit (Mexico); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Uribe, M. del R., E-mail: jlbenitesr@prodigy.net.mx [Instituto Tecnico Superior de Radiologia, Calle Leon No. 129, 63000 Tepic, Nayarit (Mexico)

    2014-08-15

    By means of Monte Carlo methods was considered the damage in the organs, induced by neutrons, of patients with cancer that receive treatment in modality of three-dimensional conformal radiotherapy (3D-CRT) with lineal accelerator Varian Ix. The objective of this work was to estimate the damage probability in radiotherapy patients, starting from the effective dose by neutrons in the organs and tissues out of the treatment region. For that a three-dimensional mannequin of equivalent tissue of 30 x 100 x 30 cm{sup 3} was modeled and spherical cells were distributed to estimate the Kerma in equivalent tissue and the absorbed dose by neutrons. With the absorbed dose the effective dose was calculated using the weighting factors for the organ type and radiation type. With the effective dose and the damage factors, considered in the ICRP 103, was considered the probability of damage induction in organs. (Author)

  8. NEUTRON IMAGING, RADIOGRAPHY AND TOMOGRAPHY.

    Energy Technology Data Exchange (ETDEWEB)

    SMITH,G.C.

    2002-03-01

    Neutrons are an invaluable probe in a wide range of scientific, medical and commercial endeavors. Many of these applications require the recording of an image of the neutron signal, either in one-dimension or in two-dimensions. We summarize the reactions of neutrons with the most important elements that are used for their detection. A description is then given of the major techniques used in neutron imaging, with emphasis on the detection media and position readout principle. Important characteristics such as position resolution, linearity, counting rate capability and sensitivity to gamma-background are discussed. Finally, the application of a subset of these instruments in radiology and tomography is described.

  9. Centrifugal quantum states of neutrons

    Science.gov (United States)

    Nesvizhevsky, V. V.; Petukhov, A. K.; Protasov, K. V.; Voronin, A. Yu.

    2008-09-01

    We propose a method for observation of the quasistationary states of neutrons localized near a curved mirror surface. The bounding effective well is formed by the centrifugal potential and the mirror Fermi potential. This phenomenon is an example of an exactly solvable “quantum bouncer” problem that can be studied experimentally. It could provide a promising tool for studying fundamental neutron-matter interactions, as well as quantum neutron optics and surface physics effects. We develop a formalism that describes quantitatively the neutron motion near the mirror surface. The effects of mirror roughness are taken into account.

  10. Ukraine experimental neutron source facility.

    Energy Technology Data Exchange (ETDEWEB)

    Gohar, Y.; Bolshinsky, I.; Nekludov, I.; Karnaukhov, I. (Nuclear Engineering Division); (INL); (Kharkov Institute of Physics and Technology)

    2008-01-01

    Kharkov Institute of Physics and Technology (KIPT) of Ukraine has a plan to construct an experimental neutron source facility. The facility has been developed for producing medical isotopes, training young nuclear professionals, supporting the Ukraine nuclear industry, providing capability for performing reactor physics, material research, and basic science experiments. Argonne National Laboratory (ANL) of USA is collaborating with KIPT on developing this facility. A driven subcritical assembly utilizing the KIPT electron accelerator with a target assembly is used to generate the neutron source. The target assembly utilizes tungsten or uranium for neutron production through photonuclear reactions with 100-KW of electron beam power. The neutron source intensity, spectrum, and spatial distribution have been studied to maximize the neutron yield and satisfy different engineering requirements. The subcritical assembly is designed to obtain the highest possible neutron flux intensity with a subcriticality of 0.98. Low enrichment uranium is used for the fuel material because it enhances the neutron source performance. Safety, reliability, and environmental considerations are included in the facility conceptual design. Horizontal neutron channels are incorporated for performing basic research including cold neutron source. This paper describes the conceptual design and summarizes some of the related analyses.

  11. Ultra-Cold Neutrons (UCN)

    Data.gov (United States)

    Federal Laboratory Consortium — Researchers working at the Los Alamos Neutron Science Center and eight other member institutions of an international collaboration are constructing the most intense...

  12. Reactor neutrons in nuclear astrophysics

    Science.gov (United States)

    Reifarth, René; Glorius, Jan; Göbel, Kathrin; Heftrich, Tanja; Jentschel, Michael; Jurado, Beatriz; Käppeler, Franz; Köster, Ulli; Langer, Christoph; Litvinov, Yuri A.; Weigand, Mario

    2017-09-01

    The huge neutron fluxes offer the possibility to use research reactors to produce isotopes of interest, which can be investigated afterwards. An example is the half-lives of long-lived isotopes like 129I. A direct usage of reactor neutrons in the astrophysical energy regime is only possible, if the corresponding ions are not at rest in the laboratory frame. The combination of an ion storage ring with a reactor and a neutron guide could open the path to direct measurements of neutron-induced cross sections on short-lived radioactive isotopes in the astrophysically interesting energy regime.

  13. Measurement of neutron diffraction with compact neutron source RANS

    Science.gov (United States)

    Ikeda, Y.; Takamura, M.; Taketani, A.; Sunaga, H.; Otake, Y.; Suzuki, H.; Kumagai, M.; Oba, Y.; Hama, T.

    2016-11-01

    Diffraction is used as a measurement technique for crystal structure. X-rays or electron beam with wavelength that is close to the lattice constant of the crystal is often used for the measurement. They have sensitivity in surface (0.01mm) of heavy metals due to the mean free path for heavy ions. Neutron diffraction has the probe of the internal structure of the heavy metals because it has a longer mean free path than that of the X-rays or the electrons. However, the neutron diffraction measurement is not widely used because large facilities are required in the many neutron sources. RANS (Riken Accelerator-driven Compact Neutron Source) is developed as a neutron source which is usable easily in laboratories and factories. In RANS, fast neutrons are generated by 7MeV protons colliding on a Be target. Some fast neutrons are moderated with polyethylene to thermal neutrons. The thermal neutrons of 10meV which have wavelength of 10nm can be used for the diffraction measurement. In this study, the texture evolution in steels was measured with RANS and the validity of the compact neutron source was proved. The texture of IF steel sheets with the thickness of 1.0mm was measured with 10minutes run. The resolution is 2% and is enough to analyze a evolution in texture due to compression/tensile deformation or a volume fraction of two phases in the steel sample. These results have proven the possibility to use compact neutron source for the analysis of mesoscopic structure of metallic materials.

  14. T-violation in neutron optics

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Y. [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1996-08-01

    Experimental method to detect a T-odd correlation term in neutron propagation through a nuclear target is discussed. The correlation term is between the neutron spin, neutron momentum and nuclear spin. (author)

  15. Fundamental physics research and neutron interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Ioffe, A. [Hahn-Meitner-Institut Berlin GmbH (Germany)

    1996-08-01

    The possibility of the use of an extremely sensitive neutron interferometry technique for the study of electromagnetic structure of the neutron and the parity non-conservative effects in neutron spin rotation is discussed. (author)

  16. Slow and Fast Light in an Electro-Absorber

    DEFF Research Database (Denmark)

    Öhman, Filip; Bermejo Ramirez, Andres; Sales, Salvador

    2006-01-01

    We demonstrate controllable and large time delay in cascaded semiconductor saturable absorbers and amplifiers. The possibility of further increasing the tuneable phase shift by utilizing field screening effects in the quantum well absorber is demonstrated....

  17. Modeling the Effect of Polychromatic Light in Quantitative Absorbance Spectroscopy

    Science.gov (United States)

    Smith, Rachel; Cantrell, Kevin

    2007-01-01

    Laboratory experiment is conducted to give the students practical experience with the principles of electronic absorbance spectroscopy. This straightforward approach creates a powerful tool for exploring many of the aspects of quantitative absorbance spectroscopy.

  18. Effect of inclusions' distribution on microwave absorbing properties of composites

    Science.gov (United States)

    Qin, Siliang; Wang, Qingguo; Qu, Zhaoming

    2013-03-01

    Effect of inclusions' spatial distributions on the permeability and permittivity of composites is studied using the generalized Maxwell-Garnett equations. The result indicates that inclusions' orientation distribution can increase the longitudinal electromagnetic parameters. For inclusions' random and orientation distribution, single and three-layer absorbers are designed and optimized using genetic algorithm. The result shows that under a given absorbing requirement, absorber with inclusions' orientation distribution is lighter and thinner than absorber with inclusions' random distribution.

  19. Slow and Fast Light in an Electro-Absorber

    DEFF Research Database (Denmark)

    Öhman, Filip; Bermejo Ramirez, Andres; Sales, Salvador

    2006-01-01

    We demonstrate controllable and large time delay in cascaded semiconductor saturable absorbers and amplifiers. The possibility of further increasing the tuneable phase shift by utilizing field screening effects in the quantum well absorber is demonstrated.......We demonstrate controllable and large time delay in cascaded semiconductor saturable absorbers and amplifiers. The possibility of further increasing the tuneable phase shift by utilizing field screening effects in the quantum well absorber is demonstrated....

  20. Method for absorbing an ion from a fluid

    Science.gov (United States)

    Gao, Huizhen; Wang, Yifeng; Bryan, Charles R.

    2007-07-03

    A method for absorbing an ion from a fluid by using dispersing an organic acid into an anion surfactant solution, mixing in a divalent-metal containing compound and a trivalent-metal containing compound and calcining the resulting solid layered double hydroxide product to form an absorbent material and then contacting the absorbent material with an aqueous solution of cations or anions to be absorbed.