WorldWideScience

Sample records for benchmark neutron fields

  1. Use of Neutron Benchmark Fields for the Validation of Dosimetry Cross Sections

    Science.gov (United States)

    Griffin, Patrick

    2016-02-01

    The evolution of validation metrics for dosimetry cross sections in neutron benchmark fields is explored. The strength of some of the metrics in providing validation evidence is examined by applying them to the 252Cf spontaneous fission standard neutron benchmark field, the 235U thermal neutron fission reference benchmark field, the ACRR pool-type reactor central cavity reference benchmark fields, and the SPR-III fast burst reactor central cavity. The IRDFF dosimetry cross section library is used in the validation study and observations are made on the amount of coverage provided to the library contents by validation data available in these benchmark fields.

  2. Neutron Reference Benchmark Field Specification: ACRR Free-Field Environment (ACRR-FF-CC-32-CL).

    Energy Technology Data Exchange (ETDEWEB)

    Vega, Richard Manuel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Parma, Edward J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Griffin, Patrick J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vehar, David W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-07-01

    This report was put together to support the International Atomic Energy Agency (IAEA) REAL- 2016 activity to validate the dosimetry community’s ability to use a consistent set of activation data and to derive consistent spectral characterizations. The report captures details of integral measurements taken in the Annular Core Research Reactor (ACRR) central cavity free-field reference neutron benchmark field. The field is described and an “a priori” calculated neutron spectrum is reported, based on MCNP6 calculations, and a subject matter expert (SME) based covariance matrix is given for this “a priori” spectrum. The results of 31 integral dosimetry measurements in the neutron field are reported.

  3. Neutron Reference Benchmark Field Specifications: ACRR Polyethylene-Lead-Graphite (PLG) Bucket Environment (ACRR-PLG-CC-32-CL).

    Energy Technology Data Exchange (ETDEWEB)

    Vega, Richard Manuel [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Parm, Edward J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Griffin, Patrick J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Vehar, David W. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-07-01

    This report was put together to support the International Atomic Energy Agency (IAEA) REAL- 2016 activity to validate the dosimetry community’s ability to use a consistent set of activation data and to derive consistent spectral characterizations. The report captures details of integral measurements taken in the Annular Core Research Reactor (ACRR) central cavity with the Polyethylene-Lead-Graphite (PLG) bucket, reference neutron benchmark field. The field is described and an “a priori” calculated neutron spectrum is reported, based on MCNP6 calculations, and a subject matter expert (SME) based covariance matrix is given for this “a priori” spectrum. The results of 37 integral dosimetry measurements in the neutron field are reported.

  4. Benchmarking of activation reaction distribution in an intermediate energy neutron field.

    Science.gov (United States)

    Ogawa, Tatsuhiko; Morev, Mikhail N; Hirota, Masahiro; Abe, Takuya; Koike, Yuya; Iwai, Satoshi; Iimoto, Takeshi; Kosako, Toshiso

    2011-07-01

    Neutron-induced reaction rate depth profiles inside concrete shield irradiated by intermediate energy neutron were calculated using a Monte-Carlo code and compared with an experiment. An irradiation field of intermediate neutron produced in the forward direction from a thick (stopping length) target bombarded by 400 MeV nucleon(-1) carbon ions was arranged at the heavy ion medical accelerator in Chiba. Ordinary concrete shield of 90 cm thickness was installed 50 cm downstream the iron target. Activation detectors of aluminum, gold and gold covered with cadmium were inserted at various depths. Irradiated samples were extracted after exposure and gamma-ray spectrometry was performed for each sample. Comparison of experimental and calculated shows good agreement for both low- and high-energy neutron-induced reaction except for (27)Al(n,X)(24)Na reaction at the surface. PMID:21515619

  5. Neutron Reference Benchmark Field Specification: ACRR 44 Inch Lead-Boron (LB44) Bucket Environment (ACRR-LB44-CC-32-CL).

    Energy Technology Data Exchange (ETDEWEB)

    Vega, Richard Manuel [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Parma, Edward J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Griffin, Patrick J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Vehar, David W. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-07-01

    This report was put together to support the International Atomic Energy Agency (IAEA) REAL- 2016 activity to validate the dosimetry community’s ability to use a consistent set of activation data and to derive consistent spectral characterizations. The report captures details of integral measurements taken in the Annular Core Research Reactor (ACRR) central cavity with the 44 inch Lead-Boron (LB44) bucket, reference neutron benchmark field. The field is described and an “a priori” calculated neutron spectrum is reported, based on MCNP6 calculations, and a subject matter expert (SME) based covariance matrix is given for this “a priori” spectrum. The results of 31 integral dosimetry measurements in the neutron field are reported.

  6. Design of Pre-collimator System for Neutronics Benchmark Experiment

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In order to carry out evaluation of neutron nuclear data, in the last "Five-Year" period, China Institute of Atomic Energy has developed a set of neutron nuclear data benchmarking test system, and used the time-of-flight technique to measure the neutron

  7. Detail analysis of fusion neutronics benchmark experiment for iron

    Energy Technology Data Exchange (ETDEWEB)

    Konno, Chikara [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan)], E-mail: konno.chikara@jaea.go.jp; Ochiai, Kentaro [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan); Wada, Masayuki [Japan Computer System, Mito 310-0805 (Japan); Takakura, Kosuke; Sato, Satoshi [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan)

    2009-06-15

    In order to specify the best nuclear data on iron, the fusion neutronics benchmark experiment on iron at Japan Atomic Energy Agency (JAEA)/Fusion Neutronics Source (FNS) was analyzed in detail with MCNP-4C and the latest nuclear data libraries, JENDL-3.3, FENDL-2.1, JEFF-3.1 and ENDF/B-VII.0. As a result, totally the calculation result with ENDF/B-VII.0 agreed with the measurement best, except that it underestimated the measured neutron flux above 10 MeV with the depth. It was noted that the calculation result with JENDL-3.3 overestimated the measured neutrons below a few keV. Through the DORT calculations based on the iron data in ENDF/B-VII.0, it was found out that the first inelastic scattering cross-section data of {sup 57}Fe in JENDL-3.3 caused the overestimation.

  8. Spectrometer equipment for neutron spectra measurements in mixed neutron/photon fields

    CERN Document Server

    Chernov, V A; Trykov, L A

    2002-01-01

    The paper describes spectrometer equipment in the IPPE experimental laboratory for neutron spectra measurement in mixed (n,gamma) fields. The laboratory was founded in 1957 and it occupies a leading position in the field of nuclear facilities radiation spectrometry and benchmark experiments in Russia. Spectrometer equipment includes spectrometers based on the organic stilbene scintillator, hydrogen counter and Bonner balls. Basic fields of spectrometer application are mixed radiation neutron spectra measurement of radionuclide sources, of nuclear reactors and accelerators; study of neutron transfer through the material, including benchmark experiments and measurement of neutron spectra in the rooms of nuclear facilities.

  9. Use of Apollo 17 Epoch Neutron Spectrum as a Benchmark in Testing LEND Collimated Sensor

    Science.gov (United States)

    Chin, Gordon; Sagdeev, R.; Milikh, G.

    2011-01-01

    The Apollo 17 neutron experiment LPNE provided a unique set of data on production of neutrons in the Lunar soil bombarded by Galactic Cosmic Rays (GCR). It serves as valuable "ground-truth" in the age of orbital remote sensing. We used the neutron data attributed to Apollo 17 epoch as a benchmark for testing the LEND's collimated sensor, as introduced by the geometry of collimator and efficiency of He3 counters. The latter is defined by the size of gas counter and pressure inside it. The intensity and energy spectrum of neutrons escaping the lunar surface are dependent on incident flux of Galactic Cosmic Rays (GCR) whose variability is associated with Solar Cycle and its peculiarities. We obtain first the share of neutrons entering through the field of view of collimator as a fraction of the total neutron flux by using the angular distribution of neutron exiting the Moon described by our Monte Carlo code. We computed next the count rate of the 3He sensor by using the neutron energy spectrum from McKinney et al. [JGR, 2006] and by consider geometry and gas pressure of the LEND sensor. Finally the neutron count rate obtained for the Apollo 17 epoch characterized by intermediate solar activity was adjusted to the LRO epoch characterized by low solar activity. It has been done by taking into account solar modulation potential, which affects the GCR flux, and in turn changes the neutron albedo flux.

  10. Benchmark experiment on vanadium assembly with D-T neutrons. Leakage neutron spectrum measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kokooo; Murata, I.; Nakano, D.; Takahashi, A. [Osaka Univ., Suita (Japan); Maekawa, F.; Ikeda, Y.

    1998-03-01

    The fusion neutronics benchmark experiments have been done for vanadium and vanadium alloy by using the slab assembly and time-of-flight (TOF) method. The leakage neutron spectra were measured from 50 keV to 15 MeV and comparison were done with MCNP-4A calculations which was made by using evaluated nuclear data of JENDL-3.2, JENDL-Fusion File and FENDL/E-1.0. (author)

  11. Benchmark experiment on vanadium assembly with D-T neutrons. In-situ measurement

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Fujio; Kasugai, Yoshimi; Konno, Chikara; Wada, Masayuki; Oyama, Yukio; Ikeda, Yujiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Murata, Isao; Kokooo; Takahashi, Akito

    1998-03-01

    Fusion neutronics benchmark experimental data on vanadium were obtained for neutrons in almost entire energies as well as secondary gamma-rays. Benchmark calculations for the experiment were performed to investigate validity of recent nuclear data files, i.e., JENDL Fusion File, FENDL/E-1.0 and EFF-3. (author)

  12. Benchmarking of the FENDL-3 Neutron Cross-section Data Starter Library for Fusion Applications

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, U., E-mail: ulrich.fischer@kit.edu [Association KIT-Euratom, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Angelone, M. [Associazione ENEA-Euratom, ENEA Fusion Division, Via E. Fermi 27, I-00044 Frascati (Italy); Bohm, T. [University of Wisconsin-Madison, 1500 Engineering Dr, Madison, WI 53706 (United States); Kondo, K. [Association KIT-Euratom, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Konno, C. [Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan); Sawan, M. [University of Wisconsin-Madison, 1500 Engineering Dr, Madison, WI 53706 (United States); Villari, R. [Associazione ENEA-Euratom, ENEA Fusion Division, Via E. Fermi 27, I-00044 Frascati (Italy); Walker, B. [University of Wisconsin-Madison, 1500 Engineering Dr, Madison, WI 53706 (United States)

    2014-06-15

    This paper summarizes the benchmark analyses performed in a joint effort of ENEA (Italy), JAEA (Japan), KIT (Germany), and the University of Wisconsin (USA) on a computational ITER benchmark and a series of 14 MeV neutron benchmark experiments. The computational benchmark revealed a modest increase of the neutron flux levels in the deep penetration regions and a substantial increase of the gas production in steel components. The comparison to experimental results showed good agreement with no substantial differences between FENDL-3.0 and FENDL-2.1 for most of the responses. In general, FENDL-3 shows an improved performance for fusion neutronics applications.

  13. Benchmarking of the FENDL-3 Neutron Cross-section Data Starter Library for Fusion Applications

    International Nuclear Information System (INIS)

    This paper summarizes the benchmark analyses performed in a joint effort of ENEA (Italy), JAEA (Japan), KIT (Germany), and the University of Wisconsin (USA) on a computational ITER benchmark and a series of 14 MeV neutron benchmark experiments. The computational benchmark revealed a modest increase of the neutron flux levels in the deep penetration regions and a substantial increase of the gas production in steel components. The comparison to experimental results showed good agreement with no substantial differences between FENDL-3.0 and FENDL-2.1 for most of the responses. In general, FENDL-3 shows an improved performance for fusion neutronics applications

  14. Neutron scattering in magnetic fields

    International Nuclear Information System (INIS)

    The use of magnetic fields in neutron scattering experimentation is reviewed briefly. Two general areas of application can be distinguished. In one the field acts to change the properties of the scattering sample; in the second the field acts on the neutron itself. Several examples are discussed. Precautions necessary for high precision polarized beam measurements are reviewed. 33 references

  15. Results of the MUSE Benchmark - 3D distribution of reaction yields and delayed neutrons in criticality calculations

    International Nuclear Information System (INIS)

    The MUSE project, carried out within the European fifth Framework Program, focuses on the coupling of a sub-critical reactor core with an external neutron source. In the first stage of the project a benchmark has been defined in order to define a reference calculational route, which is able to accurately predict the neutronics behavior in an accelerator driven system. Benchmark calculations will be carried out by several members of the project and the results will be compared, also with experimental results. The contribution of NRG to the project consists of the benchmark calculations and additional work that focuses on the calculation of 3D distributions of reaction yields. This paper discusses the non-conventional methods used to perform the benchmark calculations, including the 3D reaction yield distributions. The 3D distributions calculated for the sub-critical core will be Shown and discussed. With the ORANGE-extension to MCNP it is possible to tally 3D distributions, without adding extra cells and surfaces to the geometry and without a significant slowing down of the calculation. These are major advantages when compared to the conventional way of tallying in the MCNP-code. The distributions show details that can be understood in terms of the expected neutron behavior in the different parts of the geometry. For instance, the results show that: 1) a large number of fast neutrons is found in the fuel regions, 2) the reflector region shows an increased number of slower neutrons and 3) the reaction yield in the shielding region declines steeply. The extension therefore seems a useful tool in generating a better understanding of the behavior of neutrons throughout large and complex geometries like accelerator driven systems, but we also expect to use the extension in a variety of different fields. (authors)

  16. Computational benchmarking of fast neutron transport throughout large water thicknesses; Benchmark theorique du transport de neutrons rapides a travers de larges epaisseurs d`eau

    Energy Technology Data Exchange (ETDEWEB)

    Risch, P.; Dekens, O.; Ait Abderrahim, H. [SCK-CEN, Fuel Research Department, (Belgium); Wouters, R. de [Tractebel, Energy Engineering, (Belgium)

    1997-10-01

    Neutron dosimetry experiments seem to point our difficulties in the treatment of large water thickness like those encountered between the core baffle and the pressure vessel. This paper describes the theoretical benchmark undertaken by EDF, SCK/CEN and TRACTEBEL ENERGY ENGINEERING, concerning the transport of fast neutrons throughout a one meter cube of water, located after a U-235 fission sources plate. The results showed no major discrepancies between the calculations up to 50 cm from the source, accepting that a P3 development of the Legendre polynomials is necessary for the Sn calculations. The main differences occurred after 50 cm, reaching 20 % at the end of the water cube. This results lead us to consider an experimental benchmark, dedicated to the problem of fast neutron deep penetration in water, which has been launched at SCK/CEN. (authors). 7 refs.

  17. Neutron and gamma spectra measurements and calculations in benchmark spherical iron assemblies with sup 2 sup 5 sup 2 Cf neutron source in the centre

    CERN Document Server

    Jansky, B; Turzik, Z; Kyncl, J; Cvachovec, F; Trykov, L A; Volkov, V S

    2002-01-01

    The neutron and gamma spectra measurements have been made for benchmark iron spherical assemblies with the diameter of 30, 50 and 100 cm. The sup 2 sup 5 sup 2 Cf neutron sources with different emissions were placed into the centre of iron spheres. In the first stage of the project, independent laboratories took part in the leakage spectra measurements. The proton recoil method was used with stilbene crystals and hydrogen proportional counters. The working range of spectrometers for neutrons is in energy range from 0.01 to 16 MeV, and for gamma from 0.40 to 12 MeV. Some adequate calculations have been carried out. The propose to carefully analyse the leakage mixed neutron and gamma spectrum from iron sphere of diameter 50 cm and then adopt that field as standard.

  18. Detail analysis of fusion neutronics benchmark experiment on beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Konno, Chikara, E-mail: konno.chikara@jaea.go.j [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan); Ochiai, Kentaro; Takakura, Kosuke; Ohnishi, Seiki; Kondo, Keitaro [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan); Wada, Masayuki [Japan Computer System, Mito-shi, Ibaraki-ken 310-0805 (Japan); Sato, Satoshi [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan)

    2010-12-15

    Our previous analysis of the integral experiments (in situ and TOF experiments) on beryllium with DT neutrons at JAEA/FNS pointed out two problems by using MCNP4C and the latest nuclear data libraries; one was a strange larger neutron peak around 12 MeV appearing in the TOF experiment analysis with JEFF-3.1 and the other was an overestimation on law energy neutrons in the in situ experiment analyses with all the nuclear data libraries. We investigated reasons for these problems in detail. It was found out that the official ACE file MCJEFF3.1 of JEFF-3.1 had an inconsistency with the original JEFF-3.1, which caused the strange larger neutron peak around 12 MeV in the TOF experiment analysis. We also found out that the calculated thermal neutron peak was probably too large in the in situ experiment. On trial we examined influence of the thermal neutron scattering law data of beryllium metal in ENDF/B-VI. The result pointed out that the coherent elastic scattering cross-section data in the thermal neutron scattering law data of beryllium metal were probably too large.

  19. Analytical three-dimensional neutron transport benchmarks for verification of nuclear engineering codes. Final report

    International Nuclear Information System (INIS)

    Because of the requirement of accountability and quality control in the scientific world, a demand for high-quality analytical benchmark calculations has arisen in the neutron transport community. The intent of these benchmarks is to provide a numerical standard to which production neutron transport codes may be compared in order to verify proper operation. The overall investigation as modified in the second year renewal application includes the following three primary tasks. Task 1 on two dimensional neutron transport is divided into (a) single medium searchlight problem (SLP) and (b) two-adjacent half-space SLP. Task 2 on three-dimensional neutron transport covers (a) point source in arbitrary geometry, (b) single medium SLP, and (c) two-adjacent half-space SLP. Task 3 on code verification, includes deterministic and probabilistic codes. The primary aim of the proposed investigation was to provide a suite of comprehensive two- and three-dimensional analytical benchmarks for neutron transport theory applications. This objective has been achieved. The suite of benchmarks in infinite media and the three-dimensional SLP are a relatively comprehensive set of one-group benchmarks for isotropically scattering media. Because of time and resource limitations, the extensions of the benchmarks to include multi-group and anisotropic scattering are not included here. Presently, however, enormous advances in the solution for the planar Green's function in an anisotropically scattering medium have been made and will eventually be implemented in the two- and three-dimensional solutions considered under this grant. Of particular note in this work are the numerical results for the three-dimensional SLP, which have never before been presented. The results presented were made possible only because of the tremendous advances in computing power that have occurred during the past decade

  20. Analytical three-dimensional neutron transport benchmarks for verification of nuclear engineering codes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Ganapol, B.D.; Kornreich, D.E. [Univ. of Arizona, Tucson, AZ (United States). Dept. of Nuclear Engineering

    1997-07-01

    Because of the requirement of accountability and quality control in the scientific world, a demand for high-quality analytical benchmark calculations has arisen in the neutron transport community. The intent of these benchmarks is to provide a numerical standard to which production neutron transport codes may be compared in order to verify proper operation. The overall investigation as modified in the second year renewal application includes the following three primary tasks. Task 1 on two dimensional neutron transport is divided into (a) single medium searchlight problem (SLP) and (b) two-adjacent half-space SLP. Task 2 on three-dimensional neutron transport covers (a) point source in arbitrary geometry, (b) single medium SLP, and (c) two-adjacent half-space SLP. Task 3 on code verification, includes deterministic and probabilistic codes. The primary aim of the proposed investigation was to provide a suite of comprehensive two- and three-dimensional analytical benchmarks for neutron transport theory applications. This objective has been achieved. The suite of benchmarks in infinite media and the three-dimensional SLP are a relatively comprehensive set of one-group benchmarks for isotropically scattering media. Because of time and resource limitations, the extensions of the benchmarks to include multi-group and anisotropic scattering are not included here. Presently, however, enormous advances in the solution for the planar Green`s function in an anisotropically scattering medium have been made and will eventually be implemented in the two- and three-dimensional solutions considered under this grant. Of particular note in this work are the numerical results for the three-dimensional SLP, which have never before been presented. The results presented were made possible only because of the tremendous advances in computing power that have occurred during the past decade.

  1. Magnetic fields of neutron stars

    CERN Document Server

    Reisenegger, Andreas

    2013-01-01

    Neutron stars contain the strongest magnetic fields known in the Universe. In this paper, I discuss briefly how these magnetic fields are inferred from observations, as well as the evidence for their time-evolution. I show how these extremely strong fields are actually weak in terms of their effects on the stellar structure, as is also the case for magnetic stars on the upper main sequence and magnetic white dwarfs, which have similar total magnetic fluxes. I propose a scenario in which a stable hydromagnetic equilibrium (containing a poloidal and a toroidal field component) is established soon after the birth of the neutron star, aided by the strong compositional stratification of neutron star matter, and this state is slowly eroded by non-ideal magnetohydrodynamic processes such as beta decays and ambipolar diffusion in the core of the star and Hall drift and breaking of the solid in its crust. Over sufficiently long time scales, the fluid in the neutron star core will behave as if it were barotropic, becau...

  2. Neutron in Strong Magnetic Fields

    CERN Document Server

    Andreichikov, M A; Orlovsky, V D; Simonov, Yu A

    2013-01-01

    Relativistic world-line Hamiltonian for strongly interacting 3q systems in magnetic field is derived from the path integral for the corresponding Green's function. The neutral baryon Hamiltonian in magnetic field obeys the pseudomomentum conservation and allows a factorization of the c.m. and internal motion. The resulting expression for the baryon mass in magnetic field is written explicitly with the account of hyperfine, OPE and OGE (color Coulomb) interaction. The neutron mass is fast decreasing with magnetic field, losing 1/2 of its value at eB~0.25 GeV^2 and is nearly zero at eB~0.5 GeV^2. Possible physical consequences of the calculated mass trajectory of the neutron, M_n(B), are presented and discussed.

  3. TRIPOLI-4® - MCNP5 ITER A-lite neutronic model benchmarking

    Science.gov (United States)

    Jaboulay, J.-C.; Cayla, P.-Y.; Fausser, C.; Lee, Y.-K.; Trama, J.-C.; Li-Puma, A.

    2014-06-01

    The aim of this paper is to present the capability of TRIPOLI-4®, the CEA Monte Carlo code, to model a large-scale fusion reactor with complex neutron source and geometry. In the past, numerous benchmarks were conducted for TRIPOLI-4® assessment on fusion applications. Experiments (KANT, OKTAVIAN, FNG) analysis and numerical benchmarks (between TRIPOLI-4® and MCNP5) on the HCLL DEMO2007 and ITER models were carried out successively. In this previous ITER benchmark, nevertheless, only the neutron wall loading was analyzed, its main purpose was to present MCAM (the FDS Team CAD import tool) extension for TRIPOLI-4®. Starting from this work a more extended benchmark has been performed about the estimation of neutron flux, nuclear heating in the shielding blankets and tritium production rate in the European TBMs (HCLL and HCPB) and it is presented in this paper. The methodology to build the TRIPOLI-4® A-lite model is based on MCAM and the MCNP A-lite model (version 4.1). Simplified TBMs (from KIT) have been integrated in the equatorial-port. Comparisons of neutron wall loading, flux, nuclear heating and tritium production rate show a good agreement between the two codes. Discrepancies are mainly included in the Monte Carlo codes statistical error.

  4. Benchmarking of photon and coupled neutron and photon process of SuperMC 2.0

    International Nuclear Information System (INIS)

    Super Monte Carlo Calculation Program for Nuclear and Radiation Process (SuperMC), developed by FDS Team in China, is a multi-functional simulation program mainly based on Monte Carlo (MC) method and advanced computer technology. This paper focuses on the benchmarking of physical process of photon and coupled neutron-photon of SuperMC2.0. Integral leakage rate of photon in the spherical and hemispherical shell experiment was tested to verify the physical process of photon and coupled neutron and photon transport. Vanadium assembly experiment and ADS benchmark were given as comprehensive benchmarks. The correctness was preliminarily verified by comparing calculation results of SuperMC with experimental results and MCNP calculation results. (author)

  5. Solution of the neutronics code dynamic benchmark by finite element method

    Science.gov (United States)

    Avvakumov, A. V.; Vabishchevich, P. N.; Vasilev, A. O.; Strizhov, V. F.

    2016-10-01

    The objective is to analyze the dynamic benchmark developed by Atomic Energy Research for the verification of best-estimate neutronics codes. The benchmark scenario includes asymmetrical ejection of a control rod in a water-type hexagonal reactor at hot zero power. A simple Doppler feedback mechanism assuming adiabatic fuel temperature heating is proposed. The finite element method on triangular calculation grids is used to solve the three-dimensional neutron kinetics problem. The software has been developed using the engineering and scientific calculation library FEniCS. The matrix spectral problem is solved using the scalable and flexible toolkit SLEPc. The solution accuracy of the dynamic benchmark is analyzed by condensing calculation grid and varying degree of finite elements.

  6. Data collection of fusion neutronics benchmark experiment conducted at FNS/JAERI

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Fujio; Konno, Chikara; Kasugai, Yoshimi; Oyama, Yukio; Ikeda, Yujiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-08-01

    Fusion neutronics benchmark experimental data have been continued at the Fusion Neutronics Source (FNS) facility in JAERI. This report compiles unpublished results of the in-situ measurement experiments conducted by the end of 1996. Experimental data of neutron spectra in entire energy range, dosimetry reaction rates, gamma-ray spectrum and gamma-ray heating rates are acquired for five materials of beryllium, vanadium, iron, copper and tungsten. These experimental data along with data previously reported are effective for validating cross section data stored in evaluated nuclear data files such as JENDL. (author)

  7. Sustaining knowledge in the neutron generator community and benchmarking study.

    Energy Technology Data Exchange (ETDEWEB)

    Barrentine, Tameka C.; Kennedy, Bryan C.; Saba, Anthony W.; Turgeon, Jennifer L.; Schneider, Julia Teresa; Stubblefield, William Anthony; Baldonado, Esther

    2008-03-01

    In 2004, the Responsive Neutron Generator Product Deployment department embarked upon a partnership with the Systems Engineering and Analysis knowledge management (KM) team to develop knowledge management systems for the neutron generator (NG) community. This partnership continues today. The most recent challenge was to improve the current KM system (KMS) development approach by identifying a process that will allow staff members to capture knowledge as they learn it. This 'as-you-go' approach will lead to a sustainable KM process for the NG community. This paper presents a historical overview of NG KMSs, as well as research conducted to move toward sustainable KM.

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

    International Nuclear Information System (INIS)

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

  9. Benchmarking the inelastic neutron scattering soil carbon method

    Science.gov (United States)

    The herein described inelastic neutron scattering (INS) method of measuring soil carbon was based on a new procedure for extracting the net carbon signal (NCS) from the measured gamma spectra and determination of the average carbon weight percent (AvgCw%) in the upper soil layer (~8 cm). The NCS ext...

  10. Integral Data Benchmark of HENDL2.0/MG Compared with Neutronics Shielding Experiments

    Institute of Scientific and Technical Information of China (English)

    JIANG Jieqiong; XU Dezheng; ZHENG Shanliang; HE Zhaozhong; HU Yanglin; LI Jingjing; ZOU Jun; ZENG Qin; CHEN Mingliang; WANG Minghuang

    2009-01-01

    HENDL2.0,the latest version of the hybrid evaluated nuclear data library,was developed based upon some evaluated data from FENDL2.1 and ENDF/B-VII.To qualify and validate the working library,an integral test for the neutron production data of HENDL2.0 was performed with a series of existing spherical shell benchmark experiments (such as V,Be,Fe,Pb,Cr,Mn,Cu,Al,Si,Co,Zr,Nb,Mo,W and Ti).These experiments were simulated numerically using HENDL2.0/MG and a home-developed code VisualBUS.Calculations were conducted with both FENDL2.1/MG and FENDL2.1/MC,which are based on a continuous-energy Monte Carlo Code MCNP/4C.By comparison and analysis of the neutron leakage spectra and the integral test,benchmark results of neutron production data are presented in this paper.

  11. Deficiency in Monte Carlo simulations of coupled neutron-gamma-ray fields

    NARCIS (Netherlands)

    Maleka, Peane P.; Maucec, Marko; de Meijer, Robert J.

    2011-01-01

    The deficiency in Monte Carlo simulations of coupled neutron-gamma-ray field was investigated by benchmarking two simulation codes with experimental data. Simulations showed better correspondence with the experimental data for gamma-ray transport only. In simulations, the neutron interactions with m

  12. The possibility to use `energy plus transmutation' set-up for neutron production and transport benchmark studies

    Indian Academy of Sciences (India)

    V Wagner; A Krása; M Majerla; F Křížek; O Svoboda; A Kugler; J Adam; V M Tsoupko-Sitnikov; M I Krivopustov; I V Zhuk; W Westmeier

    2007-02-01

    The set-up `energy plus transmutation', consisting of a thick lead target and a natural uranium blanket, was irradiated by relativistic proton beams with the energy from 0.7 GeV up to 2 GeV. Neutron field was measured in different places of this set-up using different activation detectors. The possibilities of using the obtained data for benchmark studies are analyzed in this paper. Uncertainties of experimental data are shown and discussed. The experimental data are compared with results of simulation with MCNPX code.

  13. Sustaining knowledge in the neutron generator community and benchmarking study. Phase II.

    Energy Technology Data Exchange (ETDEWEB)

    Huff, Tameka B.; Stubblefield, William Anthony; Cole, Benjamin Holland, II; Baldonado, Esther

    2010-08-01

    This report documents the second phase of work under the Sustainable Knowledge Management (SKM) project for the Neutron Generator organization at Sandia National Laboratories. Previous work under this project is documented in SAND2008-1777, Sustaining Knowledge in the Neutron Generator Community and Benchmarking Study. Knowledge management (KM) systems are necessary to preserve critical knowledge within organizations. A successful KM program should focus on people and the process for sharing, capturing, and applying knowledge. The Neutron Generator organization is developing KM systems to ensure knowledge is not lost. A benchmarking study involving site visits to outside industry plus additional resource research was conducted during this phase of the SKM project. The findings presented in this report are recommendations for making an SKM program successful. The recommendations are activities that promote sharing, capturing, and applying knowledge. The benchmarking effort, including the site visits to Toyota and Halliburton, provided valuable information on how the SEA KM team could incorporate a KM solution for not just the neutron generators (NG) community but the entire laboratory. The laboratory needs a KM program that allows members of the workforce to access, share, analyze, manage, and apply knowledge. KM activities, such as communities of practice (COP) and sharing best practices, provide a solution towards creating an enabling environment for KM. As more and more people leave organizations through retirement and job transfer, the need to preserve knowledge is essential. Creating an environment for the effective use of knowledge is vital to achieving the laboratory's mission.

  14. A neutron collimator with adjustable radiation field

    International Nuclear Information System (INIS)

    An adjustable neutron collimator for neutron therapy purposes is described. The collimator is designed to give a very sharp radiation field and a high freedom of choice for the radiation geometrics. (L.E.)

  15. Development and benchmarking of higher energy neutron transport data libraries

    International Nuclear Information System (INIS)

    Neutron cross-section evaluations covering the energy range from 10/sup /minus/11/ to 100 MeV have been prepared for several materials. The principal method used to generate this data base has employed statistical-preequilibrium nuclear models, sophisticated phase shift analyses, and R-matrix techniques. The library takes advantage of formats developed for Version 6 of the Evaluated Nuclear Data File, ENDF. Methods to efficiently utilize the ENDF/B-VI representation of this library in the MCNP Monte Carlo code have been developed. MCNP results using the new library have been compared with calculated results using codes or data based upon intranuclear cascade models. 7 refs., 8 figs

  16. Parareal in time 3D numerical solver for the LWR Benchmark neutron diffusion transient model

    CERN Document Server

    Baudron, Anne-Marie A -M; Maday, Yvon; Riahi, Mohamed Kamel; Salomon, Julien

    2014-01-01

    We present a parareal in time algorithm for the simulation of neutron diffusion transient model. The method is made efficient by means of a coarse solver defined with large time steps and steady control rods model. Using finite element for the space discretization, our implementation provides a good scalability of the algorithm. Numerical results show the efficiency of the parareal method on large light water reactor transient model corresponding to the Langenbuch-Maurer-Werner (LMW) benchmark [1].

  17. EA-MC Neutronic Calculations on IAEA ADS Benchmark 3.2

    International Nuclear Information System (INIS)

    The neutronics and the transmutation properties of the IAEA ADS benchmark 3.2 setup, the 'Yalina' experiment or ISTC project B-70, have been studied through an extensive amount of 3-D Monte Carlo calculations at CERN. The simulations were performed with the state-of-the-art computer code package EA-MC, developed at CERN. The calculational approach is outlined and the results are presented in accordance with the guidelines given in the benchmark description. A variety of experimental conditions and parameters are examined; three different fuel rod configurations and three types of neutron sources are applied to the system. Reactivity change effects introduced by removal of fuel rods in both central and peripheral positions are also computed. Irradiation samples located in a total of 8 geometrical positions are examined. Calculations of capture reaction rates in 129I, 237Np and 243Am samples and of fission reaction rates in 235U, 237Np and 243Am samples are presented. Simulated neutron flux densities and energy spectra as well as spectral indices inside experimental channels are also given according to benchmark specifications. Two different nuclear data libraries, JAR-95 and JENDL-3.2, are applied for the calculations

  18. Benchmark Evaluation of the Neutron Radiography (NRAD) Reactor Upgraded LEU-Fueled Core

    Energy Technology Data Exchange (ETDEWEB)

    John D. Bess

    2001-09-01

    Benchmark models were developed to evaluate the cold-critical start-up measurements performed during the fresh core reload of the Neutron Radiography (NRAD) reactor with Low Enriched Uranium (LEU) fuel. The final upgraded core configuration with 64 fuel elements has been completed. Evaluated benchmark measurement data include criticality, control-rod worth measurements, shutdown margin, and excess reactivity. Dominant uncertainties in keff include the manganese content and impurities contained within the stainless steel cladding of the fuel and the 236U and erbium poison content in the fuel matrix. Calculations with MCNP5 and ENDF/B-VII.0 nuclear data are approximately 1.4% greater than the benchmark model eigenvalue, supporting contemporary research regarding errors in the cross section data necessary to simulate TRIGA-type reactors. Uncertainties in reactivity effects measurements are estimated to be ~10% with calculations in agreement with benchmark experiment values within 2s. The completed benchmark evaluation de-tails are available in the 2014 edition of the International Handbook of Evaluated Reactor Physics Experiments (IRPhEP Handbook). Evaluation of the NRAD LEU cores containing 56, 60, and 62 fuel elements have also been completed, including analysis of their respective reactivity effects measurements; they are also available in the IRPhEP Handbook but will not be included in this summary paper.

  19. FENDL-3 benchmark test with neutronics experiments related to fusion in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Konno, Chikara, E-mail: konno.chikara@jaea.go.jp; Ohta, Masayuki; Takakura, Kosuke; Ochiai, Kentaro; Sato, Satoshi

    2014-10-15

    Highlights: •We have benchmarked FENDL-3.0 with integral experiments with DT neutron sources in Japan. •The FENDL-3.0 is as accurate as FENDL-2.1 and JENDL-4.0 or more. •Some data in FENDL-3.0 may have some problems. -- Abstract: The IAEA supports and promotes the gathering of the best data from evaluated nuclear data libraries for each nucleus involved in fusion reactor applications and compiles these data as FENDL. In 2012, the IAEA released a major update to FENDL, FENDL-3.0, which extends the neutron energy range from 20 MeV to greater than 60 MeV for 180 nuclei. We have benchmarked FENDL-3.0 versus in situ and TOF experiments using the DT neutron source at FNS at the JAEA and TOF experiments using the DT neutron source at OKTAVIAN at Osaka University in Japan. The Monte Carlo code MCNP-5 and the ACE file of FENDL-3.0 supplied from the IAEA were used for the calculations. The results were compared with measured ones and those obtained using the previous version, FENDL-2.1, and the latest version, JENDL-4.0. It is concluded that FENDL-3.0 is as accurate as or more so than FENDL-2.1 and JENDL-4.0, although some data in FENDL-3.0 may be problematic.

  20. Magnetic fields in Neutron Stars

    CERN Document Server

    Viganò, Daniele; Miralles, Juan A; Rea, Nanda

    2015-01-01

    Isolated neutron stars show a diversity in timing and spectral properties, which has historically led to a classification in different sub-classes. The magnetic field plays a key role in many aspects of the neutron star phenomenology: it regulates the braking torque responsible for their timing properties and, for magnetars, it provides the energy budget for the outburst activity and high quiescent luminosities (usually well above the rotational energy budget). We aim at unifying this observational variety by linking the results of the state-of-the-art 2D magneto-thermal simulations with observational data. The comparison between theory and observations allows to place two strong constraints on the physical properties of the inner crust. First, strong electrical currents must circulate in the crust, rather than in the star core. Second, the innermost part of the crust must be highly resistive, which is in principle in agreement with the presence of a novel phase of matter so-called nuclear pasta phase.

  1. Benchmark experiment on titanium with DT neutron at JAEA/FNS

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, Masayuki, E-mail: ohta.masayuki@jaea.go.jp; Takakura, Kosuke; Ochiai, Kentaro; Sato, Satoshi; Konno, Chikara

    2014-10-15

    Titanium is contained in lithium titanate which is a tritium breeding material candidate. In the nuclear design, accurate nuclear data are needed. However, few benchmark experiments had been performed for titanium. We performed a benchmark experiment with a titanium assembly and a DT neutron source at JAEA/FNS. The titanium assembly was covered with Li{sub 2}O blocks in order to reduce background neutrons. Dosimetry reaction rates were measured with niobium, indium and gold foils inside the assembly. And fission rates of {sup 235}U were measured by using micro fission chambers. This experiment was analyzed by using the Monte Carlo neutron transport code MCNP5-1.40 with recent nuclear data libraries of ENDF/B-VII.0, ENDF/B-VII.1, JEFF-3.1.2, JENDL-4.0 and JENDL-4.0u1. The calculation results were compared with the measured one in order to validate the nuclear data libraries of titanium. The calculated results with ENDF/B-VII.1 agreed with the measured one the best because the (n,2n) and (n,n′{sub cont}) reaction cross section data and resonance parameters were improved.

  2. Benchmarking Benchmarks

    NARCIS (Netherlands)

    D.C. Blitz (David)

    2011-01-01

    textabstractBenchmarking benchmarks is a bundle of six studies that are inspired by the prevalence of benchmarking in academic finance research as well as in investment practice. Three studies examine if current benchmark asset pricing models adequately describe the cross-section of stock returns. W

  3. Evolution of Neutron Star Magnetic Fields

    Indian Academy of Sciences (India)

    Dipankar Bhattacharya

    2002-03-01

    This paper reviews the current status of the theoretical models of the evolution of the magnetic fields of neutron stars other than magnetars. It appears that the magnetic fields of neutron stars decay significantly only if they are in binary systems. Three major physical models for this, namely spindown-induced flux expulsion, ohmic evolution of crustal field and diamagnetic screening of the field by accreted plasma, are reviewed.

  4. Reference neutron fields for radiation monitoring

    International Nuclear Information System (INIS)

    A set of reference neutron fields, generated at the Joint Institute of Nuclear Research (JINR) for radiation monitoring, is described. A calibration algorithm is proposed for detectors used in express and individual monitoring. The reference fields cover practically the whole energy range of neutron radiation produced at the nuclear installations of the JINR (from 10-8 up to hundreds of megaelectronvolts). The set includes the fields obtained from a 252Cf source in polyethylene moderators 12.7 and 29.2 cm in diameter; a soft-radiation field produced by multiply scattered neutrons in a synchrocyclotron labyrinth; and the hard radiation field formed by neutrons leaking from a whole concrete shield surrounding a synchrocyclotron when the shield is irradiated by the secondary radiation from the accelerator chamber and target. The latter two fields appear when the synchrocyclotron of the Laboratory of Nuclear Problems operates at an energy of 660 MeV

  5. The Benchmark experiment on stainless steel bulk shielding at the Frascati neutron generator

    International Nuclear Information System (INIS)

    In the framework of the European Technology Program for NET/ITER, ENEA (Italian Agency for New Technologies, Energy and Environment) - Frascati and CEA (Commissariat a L'Energie Atomique) - Cadarache collaborated on a Bulk Shield Benchmark Experiment using the 14-MeV Frascati Neutron Generator (FNG). The aim of the experiment was to obtain accurate experimental data for improving the nuclear database and methods used in shielding designs, through a rigorous analysis of the results. The experiment consisted of the irradiation of a stainless steel block by 14-MeV neutrons. The neutron reaction rates at different depths inside the block were measured by fission chambers and activation foils characterized by different energy response ranges. The experimental results have been compared with numerical results calculated using both SN and Monte Carlo transport codes and as transport cross section library the European Fusion File (EFF). In particular, the present report describes the experimental and numerical activity, including neutron measurements and Monte Carlo calculations, carried out by the ENEA Italian Agency for New Technologies, Energy and Environment) team

  6. Evaluation of large 3600 MWth sodium-cooled fast reactor OECD neutronic benchmarks

    International Nuclear Information System (INIS)

    Within the activities of the Working Party on Scientific Issues of Reactor Systems (WPRS) of the OECD, an international collaboration is ongoing on the neutronic analyses of several Generation-IV Sodium-cooled Fast Reactor (SFR) concepts. This paper summarizes the results obtained by participants from institutions of different countries (ANL, CEA, ENEA, HZDR, JAEA, CER, KIT, UIUC) for the large core numerical benchmarks. These results have been obtained using different calculation methods and analysis tools to estimate the core reactivity and isotopic composition evolution, neutronic feedbacks and power distribution. For the different core concepts analyzed, a satisfactory agreement was obtained between participants despite the different calculation schemes used. A good agreement was generally obtained when comparing compositions after burnup, the delayed neutron fraction, the Doppler coefficient, and the sodium void worth. However, some noticeable discrepancies between the k-effective values were observed and are explained in this paper. These are mostly due to the different neutronic libraries employed (JEFF3.1, ENDFB7.0 or JENDL-4.0) and to a lesser extent the calculations methods. (author)

  7. Neutron interferometry constrains dark energy chameleon fields

    Directory of Open Access Journals (Sweden)

    H. Lemmel

    2015-04-01

    Full Text Available We present phase shift measurements for neutron matter waves in vacuum and in low pressure Helium using a method originally developed for neutron scattering length measurements in neutron interferometry. We search for phase shifts associated with a coupling to scalar fields. We set stringent limits for a scalar chameleon field, a prominent quintessence dark energy candidate. We find that the coupling constant β is less than 1.9×107 for n=1 at 95% confidence level, where n is an input parameter of the self-interaction of the chameleon field φ inversely proportional to φn.

  8. SCALE Modeling of Selected Neutronics Test Problems within the OECD UAM LWR’s Benchmark

    Directory of Open Access Journals (Sweden)

    Luigi Mercatali

    2013-01-01

    Full Text Available The OECD UAM Benchmark was launched in 2005 with the objective of determining the uncertainty in the simulation of Light Water Reactors (LWRs system calculations at all the stages of the coupled reactor physics—thermal hydraulics modeling. Within the framework of the “Neutronics Phase” of the Benchmark the solutions of some selected test cases at the cell physics and lattice physics levels are presented. The SCALE 6.1 code package has been used for the neutronics modeling of the selected exercises. Sensitivity and Uncertainty analysis (S/U based on the generalized perturbation theory has been performed in order to assess the uncertainty of the computation of some selected reactor integral parameters due to the uncertainty in the basic nuclear data. As a general trend, it has been found that the main sources of uncertainty are the 238U (n, and the 239Pu nubar for the UOX- and the MOX-fuelled test cases, respectively. Moreover, the reference solutions for the test cases obtained using Monte Carlo methodologies together with a comparison between deterministic and stochastic solutions are presented.

  9. Development of neutron calibration field using accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Mamoru [Tohoku Univ., Cyclotron and Radioisotope Center, Sendai, Miyagi (Japan)

    2003-03-01

    A brief summary is given on the fast neutron calibration fields for 1) 8 keV to 15 MeV range, and 2) 30-80 MeV range. The field for 8 keV to 15 MeV range was developed at the Fast Neutron Laboratory (FNL) at Tohoku University using a 4.5 MV pulsed Dynamitron accelerator and neutron production reactions, {sup 45}Sc(p, n), {sup 7}Li(p, n), {sup 3}H(p, n), D(d, n) and T(d, n). The latter 30-80 MeV fields are setup at TIARA of Takasaki Establishment of Japan Atomic Energy Research Institute, and at Cyclotron Radio Isotope Center (CYRIC) of Tohoku University using a 90 MeV AVF cyclotron and the {sup 7}Li(p, n) reaction. These fields have been applied for various calibration of neutron spectrometers and dosimeters, and for irradiation purposes. (author)

  10. Neutron transmission benchmark problems for iron and concrete shields in low, intermediate and high energy proton accelerator facilities

    Energy Technology Data Exchange (ETDEWEB)

    Nakane, Yoshihiro; Sakamoto, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Hayashi, Katsumi [and others

    1996-09-01

    Benchmark problems were prepared for evaluating the calculation codes and the nuclear data for accelerator shielding design by the Accelerator Shielding Working Group of the Research Committee on Reactor Physics in JAERI. Four benchmark problems: transmission of quasi-monoenergetic neutrons generated by 43 MeV and 68 MeV protons through iron and concrete shields at TIARA of JAERI, neutron fluxes in and around an iron beam stop irradiated by 500 MeV protons at KEK, reaction rate distributions inside a thick concrete shield irradiated by 6.2 GeV protons at LBL, and neutron and hadron fluxes inside an iron beam stop irradiated by 24 GeV protons at CERN are compiled in this document. Calculational configurations and neutron reaction cross section data up to 500 MeV are provided. (author)

  11. Neutron field characteristics of Ciemat's Neutron Standards Laboratory Hector Rene Vega-Carrillo

    OpenAIRE

    Guzmán-García, Karen Arlete; Méndez Villafañe, Roberto; Vega-Carrillo, Héctor René

    2015-01-01

    Monte Carlo calculations were carried out to characterize the neutron field produced by the calibration neutron sources of the Neutron Standards Laboratory at the Research Center for Energy, Environment and Technology (CIEMAT) in Spain. For 241AmBe and 252Cf neutron sources, the neutron spectra, the ambient dose equivalent rates and the total neutron fluence rates were estimated. In the calibration hall, there are several items that modify the neutron field. To evaluate their effects differen...

  12. 239Pu Prompt Fission Neutron Spectra Impact on a Set of Criticality and Experimental Reactor Benchmarks

    Science.gov (United States)

    Peneliau, Y.; Litaize, O.; Archier, P.; De Saint Jean, C.

    2014-04-01

    A large set of nuclear data are investigated to improve the calculation predictions of the new neutron transport simulation codes. With the next generation of nuclear power plants (GEN IV projects), one expects to reduce the calculated uncertainties which are mainly coming from nuclear data and are still very important, before taking into account integral information in the adjustment process. In France, future nuclear power plant concepts will probably use MOX fuel, either in Sodium Fast Reactors or in Gas Cooled Fast Reactors. Consequently, the knowledge of 239Pu cross sections and other nuclear data is crucial issue in order to reduce these sources of uncertainty. The Prompt Fission Neutron Spectra (PFNS) for 239Pu are part of these relevant data (an IAEA working group is even dedicated to PFNS) and the work presented here deals with this particular topic. The main international data files (i.e. JEFF-3.1.1, ENDF/B-VII.0, JENDL-4.0, BRC-2009) have been considered and compared with two different spectra, coming from the works of Maslov and Kornilov respectively. The spectra are first compared by calculating their mathematical moments in order to characterize them. Then, a reference calculation using the whole JEFF-3.1.1 evaluation file is performed and compared with another calculation performed with a new evaluation file, in which the data block containing the fission spectra (MF=5, MT=18) is replaced by the investigated spectra (one for each evaluation). A set of benchmarks is used to analyze the effects of PFNS, covering criticality cases and mock-up cases in various neutron flux spectra (thermal, intermediate, and fast flux spectra). Data coming from many ICSBEP experiments are used (PU-SOL-THERM, PU-MET-FAST, PU-MET-INTER and PU-MET-MIXED) and French mock-up experiments are also investigated (EOLE for thermal neutron flux spectrum and MASURCA for fast neutron flux spectrum). This study shows that many experiments and neutron parameters are very sensitive to

  13. Magnetic Field Evolution During Neutron Star Recycling

    CERN Document Server

    Cumming, A

    2004-01-01

    I describe work on two aspects of magnetic field evolution relevant for the "recycling" scenario for making millisecond radio pulsars. First, many of the theoretical ideas for bringing about accretion-induced field decay rely on dissipation of currents in the neutron star crust. I discuss field evolution in the crust due to the Hall effect, and outline when it dominates Ohmic decay. This emphasises the importance of understanding the impurity level in the crust. Second, I briefly discuss the progress that has been made in understanding the magnetic fields of neutron stars currently accreting matter in low mass X-ray binaries. In particular, thermonuclear X-ray bursts offer a promising probe of the magnetic field of these neutron stars.

  14. Validation and benchmarking of calculation methods for photon and neutron transport at cask configurations

    International Nuclear Information System (INIS)

    The reliability of calculation tools to evaluate and calculate dose rates appearing behind multi-layered shields is important with regard to the certification of transport and storage casks. Actual benchmark databases like SINBAD do not offer such configurations because they were developed for reactor and accelerator purposes. Due to this, a bench-mark-suite based on own experiments that contain dose rates measured in different distances and levels from a transport and storage cask and on a public benchmark to validate Monte-Carlo-transport-codes has been developed. The analysed and summarised experiments include a 60Co point-source located in a cylindrical cask, a 252Cf line-source shielded by iron and polyethylene (PE) and a bare 252Cf source moderated by PE in a concrete-labyrinth with different inserted shielding materials to quantify neutron streaming effects on measured dose rates. In detail not only MCNPTM (version 5.1.6) but also MAVRIC, included in the SCALE 6.1 package, have been compared for photon and neutron transport. Aiming at low deviations between calculation and measurement requires precise source term specification and exact measurements of the dose rates which have been evaluated carefully including known uncertainties. In MAVRIC different source-descriptions with respect to the group-structure of the nuclear data library are analysed for the calculation of gamma dose rates because the energy lines of 60Co can only be modelled in groups. In total the comparison shows that MCNPTM fits very wall to the measurements within up to two standard deviations and that MAVRIC behaves similarly under the prerequisite that the source-model can be optimized. (author)

  15. Symmetry energy, neutron skin, and neutron star radius from chiral effective field theory interactions

    OpenAIRE

    Hebeler, K.; Schwenk, A.

    2014-01-01

    We discuss neutron matter calculations based on chiral effective field theory interactions and their predictions for the symmetry energy, the neutron skin of 208 Pb, and for the radius of neutron stars.

  16. Applications of Neutron Bubble Dosimeters for Neutron Dose Monitoring in Mixed n-γ Fields

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Bubble dosimeter is a promising technology in the field of neutron dosimetry. It provides real-time monitoring of neutron dose, stable energy response over wide range of neutron energy, and a very low

  17. Parareal in time 3D numerical solver for the LWR Benchmark neutron diffusion transient model

    International Nuclear Information System (INIS)

    In this paper we present a time-parallel algorithm for the 3D neutrons calculation of a transient model in a nuclear reactor core. The neutrons calculation consists in numerically solving the time dependent diffusion approximation equation, which is a simplified transport equation. The numerical resolution is done with finite elements method based on a tetrahedral meshing of the computational domain, representing the reactor core, and time discretization is achieved using a θ-scheme. The transient model presents moving control rods during the time of the reaction. Therefore, cross-sections (piecewise constants) are taken into account by interpolations with respect to the velocity of the control rods. The parallelism across the time is achieved by an adequate use of the parareal in time algorithm to the handled problem. This parallel method is a predictor corrector scheme that iteratively combines the use of two kinds of numerical propagators, one coarse and one fine. Our method is made efficient by means of a coarse solver defined with large time step and fixed position control rods model, while the fine propagator is assumed to be a high order numerical approximation of the full model. The parallel implementation of our method provides a good scalability of the algorithm. Numerical results show the efficiency of the parareal method on large light water reactor transient model corresponding to the Langenbuch–Maurer–Werner benchmark

  18. Parareal in time 3D numerical solver for the LWR Benchmark neutron diffusion transient model

    Energy Technology Data Exchange (ETDEWEB)

    Baudron, Anne-Marie, E-mail: anne-marie.baudron@cea.fr [Laboratoire de Recherche Conventionné MANON, CEA/DEN/DANS/DM2S and UPMC-CNRS/LJLL (France); CEA-DRN/DMT/SERMA, CEN-Saclay, 91191 Gif sur Yvette Cedex (France); Lautard, Jean-Jacques, E-mail: jean-jacques.lautard@cea.fr [Laboratoire de Recherche Conventionné MANON, CEA/DEN/DANS/DM2S and UPMC-CNRS/LJLL (France); CEA-DRN/DMT/SERMA, CEN-Saclay, 91191 Gif sur Yvette Cedex (France); Maday, Yvon, E-mail: maday@ann.jussieu.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7598, Laboratoire Jacques-Louis Lions and Institut Universitaire de France, F-75005, Paris (France); Laboratoire de Recherche Conventionné MANON, CEA/DEN/DANS/DM2S and UPMC-CNRS/LJLL (France); Brown Univ, Division of Applied Maths, Providence, RI (United States); Riahi, Mohamed Kamel, E-mail: riahi@cmap.polytechnique.fr [Laboratoire de Recherche Conventionné MANON, CEA/DEN/DANS/DM2S and UPMC-CNRS/LJLL (France); CMAP, Inria-Saclay and X-Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex (France); Salomon, Julien, E-mail: salomon@ceremade.dauphine.fr [CEREMADE, Univ Paris-Dauphine, Pl. du Mal. de Lattre de Tassigny, F-75016, Paris (France)

    2014-12-15

    In this paper we present a time-parallel algorithm for the 3D neutrons calculation of a transient model in a nuclear reactor core. The neutrons calculation consists in numerically solving the time dependent diffusion approximation equation, which is a simplified transport equation. The numerical resolution is done with finite elements method based on a tetrahedral meshing of the computational domain, representing the reactor core, and time discretization is achieved using a θ-scheme. The transient model presents moving control rods during the time of the reaction. Therefore, cross-sections (piecewise constants) are taken into account by interpolations with respect to the velocity of the control rods. The parallelism across the time is achieved by an adequate use of the parareal in time algorithm to the handled problem. This parallel method is a predictor corrector scheme that iteratively combines the use of two kinds of numerical propagators, one coarse and one fine. Our method is made efficient by means of a coarse solver defined with large time step and fixed position control rods model, while the fine propagator is assumed to be a high order numerical approximation of the full model. The parallel implementation of our method provides a good scalability of the algorithm. Numerical results show the efficiency of the parareal method on large light water reactor transient model corresponding to the Langenbuch–Maurer–Werner benchmark.

  19. Benchmarking mean-field approximations to level densities

    Science.gov (United States)

    Alhassid, Y.; Bertsch, G. F.; Gilbreth, C. N.; Nakada, H.

    2016-04-01

    We assess the accuracy of finite-temperature mean-field theory using as a standard the Hamiltonian and model space of the shell model Monte Carlo calculations. Two examples are considered: the nucleus 162Dy, representing a heavy deformed nucleus, and 148Sm, representing a nearby heavy spherical nucleus with strong pairing correlations. The errors inherent in the finite-temperature Hartree-Fock and Hartree-Fock-Bogoliubov approximations are analyzed by comparing the entropies of the grand canonical and canonical ensembles, as well as the level density at the neutron resonance threshold, with shell model Monte Carlo calculations, which are accurate up to well-controlled statistical errors. The main weak points in the mean-field treatments are found to be: (i) the extraction of number-projected densities from the grand canonical ensembles, and (ii) the symmetry breaking by deformation or by the pairing condensate. In the absence of a pairing condensate, we confirm that the usual saddle-point approximation to extract the number-projected densities is not a significant source of error compared to other errors inherent to the mean-field theory. We also present an alternative formulation of the saddle-point approximation that makes direct use of an approximate particle-number projection and avoids computing the usual three-dimensional Jacobian of the saddle-point integration. We find that the pairing condensate is less amenable to approximate particle-number projection methods because of the explicit violation of particle-number conservation in the pairing condensate. Nevertheless, the Hartree-Fock-Bogoliubov theory is accurate to less than one unit of entropy for 148Sm at the neutron threshold energy, which is above the pairing phase transition. This result provides support for the commonly used "back-shift" approximation, treating pairing as only affecting the excitation energy scale. When the ground state is strongly deformed, the Hartree-Fock entropy is significantly

  20. FIELD CORRECTION FACTORS FOR PERSONAL NEUTRON DOSEMETERS.

    Science.gov (United States)

    Luszik-Bhadra, M

    2016-09-01

    A field-dependent correction factor can be obtained by comparing the readings of two albedo neutron dosemeters fixed in opposite directions on a polyethylene sphere to the H*(10) reading as determined with a thermal neutron detector in the centre of the same sphere. The work shows that the field calibration technique as used for albedo neutron dosemeters can be generalised for all kind of dosemeters, since H*(10) is a conservative estimate of the sum of the personal dose equivalents Hp(10) in two opposite directions. This result is drawn from reference values as determined by spectrometers within the EVIDOS project at workplace of nuclear installations in Europe. More accurate field-dependent correction factors can be achieved by the analysis of several personal dosimeters on a phantom, but reliable angular responses of these dosemeters need to be taken into account. PMID:26493946

  1. Benchmarking mean-field approximations to level densities

    CERN Document Server

    Alhassid, Y; Gilbreth, C N; Nakada, H

    2015-01-01

    We assess the accuracy of finite-temperature mean-field theory using as a standard the Hamiltonian and model space of the shell model Monte Carlo calculations. Two examples are considered: the nucleus $^{162}$Dy, representing a heavy deformed nucleus, and $^{148}$Sm, representing a nearby heavy spherical nucleus with strong pairing correlations. The errors inherent in the finite-temperature Hartree-Fock and Hartree-Fock-Bogoliubov approximations are analyzed by comparing the entropies of the grand canonical and canonical ensembles, as well as the level density at the neutron resonance threshold, with shell model Monte Carlo (SMMC) calculations, which are accurate up to well-controlled statistical errors. The main weak points in the mean-field treatments are seen to be: (i) the extraction of number-projected densities from the grand canonical ensembles, and (ii) the symmetry breaking by deformation or by the pairing condensate. In the absence of a pairing condensate, we confirm that the usual saddle-point appr...

  2. Field Ion Source Development for Neutron Generators

    Energy Technology Data Exchange (ETDEWEB)

    B. Bargsten Johnson; P. R. Schwoebel; C. E. Holland; P. J. Resnick; K. L. Hertz; D. L. Chichester

    2012-01-01

    An ion source based on the principles of electrostatic field desorption is being developed to improve the performance of existing compact neutron generators. The ion source is an array of gated metal tips derived from field electron emitter array microfabrication technology. A comprehensive summary of development and experimental activities is presented. Many structural modifications to the arrays have been incorporated to achieve higher tip operating fields, while lowering fields at the gate electrode to prevent gate field electron emission which initiates electrical breakdown in the array. The latest focus of fabrication activities has been on rounding the gate electrode edge and surrounding the gate electrode with dielectric material. Array testing results have indicated a steady progression of increased array tip operating fields with each new design tested. The latest arrays have consistently achieved fields beyond those required for the onset of deuterium desorption ({approx}20 V/nm), and have demonstrated the desorption of deuterium at fields up to 36 V/nm. The number of ions desorbed from an array has been quantified, and field desorption of metal tip substrate material from array tips has been observed for the first time. Gas-phase field ionization studies with {approx}10,000 tip arrays have achieved deuterium ion currents of {approx}50 nA. Neutron production by field ionization has yielded {approx}10{sup 2} n/s from {approx}1 mm{sup 2} of array area using the deuterium-deuterium fusion reaction at 90 kV.

  3. Field ion source development for neutron generators

    Energy Technology Data Exchange (ETDEWEB)

    Bargsten Johnson, B. [University of New Mexico, Albuquerque, NM 87131 (United States); Schwoebel, P.R., E-mail: schwoebel@chtm.unm.edu [University of New Mexico, Albuquerque, NM 87131 (United States); Holland, C.E. [SRI International, Menlo Park, CA 94025 (United States); Resnick, P.J. [Sandia National Laboratories, Albuquerque, NM 87123 (United States); Hertz, K.L. [Sandia National Laboratories, Livermore, CA 94551 (United States); Chichester, D.L. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States)

    2012-01-21

    An ion source based on the principles of electrostatic field desorption is being developed to improve the performance of existing compact neutron generators. The ion source is an array of gated metal tips derived from field electron emitter array microfabrication technology. A comprehensive summary of development and experimental activities is presented. Many structural modifications to the arrays have been incorporated to achieve higher tip operating fields, while lowering fields at the gate electrode to prevent gate field electron emission which initiates electrical breakdown in the array. The latest focus of fabrication activities has been on rounding the gate electrode edge and surrounding the gate electrode with dielectric material. Array testing results have indicated a steady progression of increased array tip operating fields with each new design tested. The latest arrays have consistently achieved fields beyond those required for the onset of deuterium desorption ({approx}20 V/nm), and have demonstrated the desorption of deuterium at fields up to 36 V/nm. The number of ions desorbed from an array has been quantified, and field desorption of metal tip substrate material from array tips has been observed for the first time. Gas-phase field ionization studies with {approx}10,000 tip arrays have achieved deuterium ion currents of {approx}50 nA. Neutron production by field ionization has yielded {approx}10{sup 2} n/s from {approx}1 mm{sup 2} of array area using the deuterium-deuterium fusion reaction at 90 kV.

  4. Neutron stars and their magnetic fields

    CERN Document Server

    Reisenegger, Andreas

    2008-01-01

    Neutron stars have the strongest magnetic fields known anywhere in the Universe. In this review, I intend to give a pedagogical discussion of some of the related physics. Neutron stars exist because of Pauli's exclusion principle, in two senses: 1) It makes it difficult to squeeze particles too close together, in this way allowing a mechanical equilibrium state in the presence of extremely strong gravity. 2) The occupation of low-energy proton and electron states makes it impossible for low-energy neutrons to beta decay. A corollary of the second statement is that charged particles are necessarily present inside a neutron star, allowing currents to flow. Since these particles are degenerate, they collide very little, and therefore make it possible for the star to support strong, organized magnetic fields over long times. These show themselves in pulsars and are the most likely energy source for the high X-ray and gamma-ray luminosity ``magnetars''. I briefly discuss the possible origin of this field and some ...

  5. Flux Expulsion Field Evolution in Neutron Stars

    CERN Document Server

    Jahan-Miri, M

    1999-01-01

    Models for the evolution of magnetic fields of neutron stars are constructed, assuming the field is embedded in the proton superconducting core of the star. The rate of expulsion of the magnetic flux out of the core, or equivalently the velocity of outward motion of flux-carrying proton-vortices is determined from a solution of the Magnus equation of motion for these vortices. A force due to the pinning interaction between the proton-vortices and the neutron-superfluid vortices is also taken into account in addition to the other more conventional forces acting on the proton-vortices. Alternative models for the field evolution are considered based on the different possibilities discussed for the effective values of the various forces. The coupled spin and magnetic evolution of single pulsars as well as those processed in low-mass binary systems are computed, for each of the models. The predicted lifetimes of active pulsars, field strengths of the very old neutron stars, and distribution of the magnetic fields ...

  6. Gravitational field energy contribution to the neutron star mass

    OpenAIRE

    Dyrda, M.; Kinasiewicz, B.; Kutschera, M.; Szmaglinski, A.

    2006-01-01

    Neutron stars are discussed as laboratories of physics of strong gravitational fields. The mass of a neutron star is split into matter energy and gravitational field energy contributions. The energy of the gravitational field of neutron stars is calculated with three different approaches which give the same result. It is found that up to one half of the gravitational mass of maximum mass neutron stars is comprised by the gravitational field energy. Results are shown for a number of realistic ...

  7. Photon spectrometry in thermal neutron standard field

    CERN Document Server

    Kudo, K; Koshikawa, S; Toyokawa, H; Ohgaki, H; Matzke, M

    2002-01-01

    An NE213 liquid scintillation counter (5.08 cm in diameter and 5.08 cm long) with an LiF filter was used to measure the energy distribution of photons mixed in a thermal neutron field. The response function matrix of photons in an energy range up to 10 MeV was calculated by the EGS4/PRESTA code and properly folded with a resolution function. Pulse height spectra measured with a set of reference gamma-ray sources were compared to the calculated response function and agreed very well for all reference gamma-ray sources. The GRAVEL and MIEKE codes from the HEPRO program were used to unfold measured pulse height spectra. Energy distributions obtained by the unfolding were applied to evaluate the effective dose equivalent of photons mixed in a thermal neutron field.

  8. Calibration of the IRD two-component TLD albedo neutron dosemeter in some moderated neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, Bruno M.; Silva, Ademir X. da, E-mail: bfreitas@nuclear.ufrj.br, E-mail: ademir@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Martins, Marcelo M.; Pereira, Walsan W.; Mauricio, Claudia L.P., E-mail: marcelo@ird.gov.br, E-mail: walsan@ird.gov.br, E-mail: claudia@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    In some stray neutron fields, like those found in practices involving the handling of radionuclide sources, the neutron calibration factor for albedo neutron dosemeter can vary widely compared to the factor for bare sources. This is the case for well logging, which is the area with the largest number of workers exposed to neutrons in Brazil. The companies employ routinely {sup 241}Am-Be neutron sources. The albedo response variation is mainly due to the presence of scattered and moderated neutrons. This paper studies the response variation of the two-component TLD albedo neutron dosemeter used in the neutron individual monitoring service of Instituto de Radioprotecao e Dosimetria, in different radionuclide neutron source beams. The neutron spectra were evaluated applying a Bonner sphere spectrometer with a {sup 6}LiI(Eu) detector in the Brazilian National Metrology Neutron Laboratory. Standard neutron sources of {sup 241}Am-Be and {sup 252}Cf were employed, besides {sup 238}Pu-Be. Measurements were also made with scattered and moderated neutron beams, including {sup 252}Cf(D{sub 2}O) reference spectrum, {sup 241}Am-Be moderated with paraffin and silicone and a thermal neutron flux facility. New neutron calibration factors, as a function of the incident to albedo neutron ratio, were proposed for use in the albedo algorithm for occupational fields where the primary neutron beam is one of those studied sources. (author)

  9. Neutron Cross Section Processing Methods for Improved Integral Benchmarking of Unresolved Resonance Region Evaluations

    Science.gov (United States)

    Walsh, Jonathan A.; Forget, Benoit; Smith, Kord S.; Brown, Forrest B.

    2016-03-01

    In this work we describe the development and application of computational methods for processing neutron cross section data in the unresolved resonance region (URR). These methods are integrated with a continuous-energy Monte Carlo neutron transport code, thereby enabling their use in high-fidelity analyses. Enhanced understanding of the effects of URR evaluation representations on calculated results is then obtained through utilization of the methods in Monte Carlo integral benchmark simulations of fast spectrum critical assemblies. First, we present a so-called on-the-fly (OTF) method for calculating and Doppler broadening URR cross sections. This method proceeds directly from ENDF-6 average unresolved resonance parameters and, thus, eliminates any need for a probability table generation pre-processing step in which tables are constructed at several energies for all desired temperatures. Significant memory reduction may be realized with the OTF method relative to a probability table treatment if many temperatures are needed. Next, we examine the effects of using a multi-level resonance formalism for resonance reconstruction in the URR. A comparison of results obtained by using the same stochastically-generated realization of resonance parameters in both the single-level Breit-Wigner (SLBW) and multi-level Breit-Wigner (MLBW) formalisms allows for the quantification of level-level interference effects on integrated tallies such as keff and energy group reaction rates. Though, as is well-known, cross section values at any given incident energy may differ significantly between single-level and multi-level formulations, the observed effects on integral results are minimal in this investigation. Finally, we demonstrate the calculation of true expected values, and the statistical spread of those values, through independent Monte Carlo simulations, each using an independent realization of URR cross section structure throughout. It is observed that both probability table

  10. Compilation of neutron flux density spectra and reaction rates in different neutron fields. V.3

    International Nuclear Information System (INIS)

    Upon the recommendation of the International Working Group of Reactor Radiation Measurements (IWGRRM) a compilation of documents containing neutron flux density spectra and the reaction rates obtained by activiation and fission foils in different neutron fields is presented

  11. Benchmarking of the WIMSD/CITATION deterministic code system for the neutronic calculations of TRIGA Mark-III research reactors

    International Nuclear Information System (INIS)

    Highlights: • Benchmark study performed for the neutronic calculations of TRIGA research reactors. • WIMSD-5B/CITATION is the utilized code system along with the WIMSD-IAEA-69 library. • The studied condensed spectra are five and seven energy groups spectra. • Analyzed: lattice parameters, reactivities, CR worth, flux and power distribution. • The lattice and neutronic parameters showed the accuracy of both condensed spectra. - Abstract: The objective of this paper is to assess the suitability and accuracy of the deterministic diffusion method for the neutronic calculations of the TRIGA Mark-III research reactors using the WIMSD/CITATION code system in proposed condensed energy spectra of five and seven energy groups with one and three thermal groups respectively. The utilized cell transport calculations code and core diffusion calculations code are the WIMSD-5B and the CITVAP v3.1 codes respectively, along with the WIMSD-IAEA-69 nuclear data library. Firstly, the assessment goes through analyzing the integral parameters – keff, ρ238, δ235, δ238, and C* – of the TRX and BAPL benchmark lattices and comparison with experimental and previous reference results using other ENDLs at the full energy spectra which show good agreement with the references at both spectra. Secondly, evaluation of the 3D nuclear characteristics of three different cores of the TRR-1/M1 TRIGA Mark-III Thai research reactor at the condensed energy spectra. The results include the excess reactivities of the cores and the worth of selected control rods which were compared with reference Monte Carlo results and experimental values. The results show good agreement with the references at both energy spectra and the better accuracy are attainable in the five energy groups spectrum. The results also include neutron flux distributions which are evaluated for future comparisons with other calculational techniques even they are comparable to reactors and fuels of the same type. The

  12. Research of Multi Detectors of Neutron Spectrum in Mix Fields

    Institute of Scientific and Technical Information of China (English)

    LI; Wei; CHEN; Jun; WANG; Zhi-qiang; LI; Chun-juan; LIU; Yi-na; LUO; Hai-long; ZHANG; Wei-hua

    2013-01-01

    This neutron spectrometer can be used to measure neutron spectrum and neutron equivalent dosimetry.The range of neutron spectrum is thermal-20 MeV,and the range of neutron equivalent dosimetry is 1μSv·h-1-4 mSv·h-1.The sensor head of the neutron spectrum of multi detectors in mix fields houses five gas-filled sensors and a photo-scintillator column.There are two boron tri-fluoride(BF3)and three hydrogen

  13. The Response of Alanine Dosimeters in Thermal Neutron Fields

    DEFF Research Database (Denmark)

    Schmitz, T.; Bassler, Niels; Sharpe, P.;

    Purpose: Boron Neutron Capture Therapy (BNCT) is a special kind of particle therapy, based on the neutron induced fission of the boron isotope 10B [1]. We have performed dosimetry experiments on the mixed neutron and gamma fields at the TRIGA Mark II research reactor in Mainz. Commonly, dosimetry...

  14. Structure of Rotating Neutron Stars in Uniform Strong Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    WEN De-Hua; CHEN Wei; LIU Liang-Gang

    2007-01-01

    Properties and deformations of the rotating neutron stars in uniform strong magnetic field are calculated.The magnetic field will soften the equation of state of the neutron star matters and make an obvious effect on the structure of the rotating neutron star.If the magnetic field is superstrong (B = 1017 T),the mass,radius,and the deformation will become smaller effectively.

  15. Characterization of neutron field in a NPP workplace.

    Science.gov (United States)

    Breznik, B; Pochat, J L; Muller, H; Asselineau, B; Pavlin, M

    2007-01-01

    At the Krsko Nuclear Power Plant (NPP), albedo dosimeters are used for personal neutron dosimetry. Spectrometric measurements allow determination of reference dosimetric values of realistic neutron fields to be used for calibration of albedo dosimeters. The Laboratory for Neutron Metrology and Dosimetry from the Institute for Radiological Protection and Nuclear Safety (IRSN) was in charge of characterising neutron fields in the plant at two representative points with high neutron and gamma dose rate. Calibration of the dosimeters in the workplace used to be performed only by a spherical survey meter. Based on the reference dosimetric values, the Plant Dosimetry Laboratory has verified the response of albedo dosimeters.

  16. Characterization of neutron field in a NPP workplace

    International Nuclear Information System (INIS)

    At the Krsko Nuclear Power Plant (NPP), albedo dosimeters are used for personal neutron dosimetry. Spectrometric measurements allow determination of reference dosimetric values of realistic neutron fields to be used for calibration of albedo dosimeters. The Laboratory for Neutron Metrology and Dosimetry from the Inst. for Radiological Protection and Nuclear Safety (IRSN) was in charge of characterising neutron fields in the plant at two representative points with high neutron and gamma dose rate. Calibration of the dosimeters in the workplace used to be performed only by a spherical survey meter. Based on the reference dosimetric values, the Plant Dosimetry Laboratory has verified the response of albedo dosimeters. (authors)

  17. Characterization of neutron field in a NPP workplace.

    Science.gov (United States)

    Breznik, B; Pochat, J L; Muller, H; Asselineau, B; Pavlin, M

    2007-01-01

    At the Krsko Nuclear Power Plant (NPP), albedo dosimeters are used for personal neutron dosimetry. Spectrometric measurements allow determination of reference dosimetric values of realistic neutron fields to be used for calibration of albedo dosimeters. The Laboratory for Neutron Metrology and Dosimetry from the Institute for Radiological Protection and Nuclear Safety (IRSN) was in charge of characterising neutron fields in the plant at two representative points with high neutron and gamma dose rate. Calibration of the dosimeters in the workplace used to be performed only by a spherical survey meter. Based on the reference dosimetric values, the Plant Dosimetry Laboratory has verified the response of albedo dosimeters. PMID:17416593

  18. Standard Guide for Benchmark Testing of Light Water Reactor Calculations

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This guide covers general approaches for benchmarking neutron transport calculations in light water reactor systems. A companion guide (Guide E2005) covers use of benchmark fields for testing neutron transport calculations and cross sections in well controlled environments. This guide covers experimental benchmarking of neutron fluence calculations (or calculations of other exposure parameters such as dpa) in more complex geometries relevant to reactor surveillance. Particular sections of the guide discuss: the use of well-characterized benchmark neutron fields to provide an indication of the accuracy of the calculational methods and nuclear data when applied to typical cases; and the use of plant specific measurements to indicate bias in individual plant calculations. Use of these two benchmark techniques will serve to limit plant-specific calculational uncertainty, and, when combined with analytical uncertainty estimates for the calculations, will provide uncertainty estimates for reactor fluences with ...

  19. Development of magnetic field imaging using polarized pulsed neutrons

    International Nuclear Information System (INIS)

    Magnetic field imaging using polarized pulsed neutrons is one of the most attractive applications of the energy-resolved neutron imaging technique. As the interaction between magnetic fields and a neutron spin depends on the neutron wavelength, analysis of the wavelength dependent polarization makes it possible to quantify the both magnetic field strength and direction. Hence, the combination of Time-of-flight method of pulsed neutron beam and three-dimensional polarization analysis is very suitable to the neutron magnetic field imaging technique. In this paper, we will explain about the results on magnetic steel sample and on spatial magnetic field from the electromagnet performed at BL10 of MLF in J-PARC. (author)

  20. ENDF/B-VII.1 Neutron Cross Section Data Testing with Critical Assembly Benchmarks and Reactor Experiments

    Science.gov (United States)

    Kahler, A. C.; MacFarlane, R. E.; Mosteller, R. D.; Kiedrowski, B. C.; Frankle, S. C.; Chadwick, M. B.; McKnight, R. D.; Lell, R. M.; Palmiotti, G.; Hiruta, H.; Herman, M.; Arcilla, R.; Mughabghab, S. F.; Sublet, J. C.; Trkov, A.; Trumbull, T. H.; Dunn, M.

    2011-12-01

    The ENDF/B-VII.1 library is the latest revision to the United States' Evaluated Nuclear Data File (ENDF). The ENDF library is currently in its seventh generation, with ENDF/B-VII.0 being released in 2006. This revision expands upon that library, including the addition of new evaluated files (was 393 neutron files previously, now 423 including replacement of elemental vanadium and zinc evaluations with isotopic evaluations) and extension or updating of many existing neutron data files. Complete details are provided in the companion paper [M. B. Chadwick et al., "ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data," Nuclear Data Sheets, 112, 2887 (2011)]. This paper focuses on how accurately application libraries may be expected to perform in criticality calculations with these data. Continuous energy cross section libraries, suitable for use with the MCNP Monte Carlo transport code, have been generated and applied to a suite of nearly one thousand critical benchmark assemblies defined in the International Criticality Safety Benchmark Evaluation Project's International Handbook of Evaluated Criticality Safety Benchmark Experiments. This suite covers uranium and plutonium fuel systems in a variety of forms such as metallic, oxide or solution, and under a variety of spectral conditions, including unmoderated (i.e., bare), metal reflected and water or other light element reflected. Assembly eigenvalues that were accurately predicted with ENDF/B-VII.0 cross sections such as unmoderated and uranium reflected 235U and 239Pu assemblies, HEU solution systems and LEU oxide lattice systems that mimic commercial PWR configurations continue to be accurately calculated with ENDF/B-VII.1 cross sections, and deficiencies in predicted eigenvalues for assemblies containing selected materials, including titanium, manganese, cadmium and tungsten are greatly reduced. Improvements are also confirmed for selected

  1. ENDF/B-VII.1 Neutron Cross Section Data Testing with Critical Assembly Benchmarks and Reactor Experiments

    International Nuclear Information System (INIS)

    The ENDF/B-VII.1 library is the latest revision to the United States' Evaluated Nuclear Data File (ENDF). The ENDF library is currently in its seventh generation, with ENDF/B-VII.0 being released in 2006. This revision expands upon that library, including the addition of new evaluated files (was 393 neutron files previously, now 418 including replacement of elemental vanadium and zinc evaluations with isotopic evaluations) and extension or updating of many existing neutron data files. Complete details are provided in the companion paper [1]. This paper focuses on how accurately application libraries may be expected to perform in criticality calculations with these data. Continuous energy cross section libraries, suitable for use with the MCNP Monte Carlo transport code, have been generated and applied to a suite of nearly one thousand critical benchmark assemblies defined in the International Criticality Safety Benchmark Evaluation Project's International Handbook of Evaluated Criticality Safety Benchmark Experiments. This suite covers uranium and plutonium fuel systems in a variety of forms such as metallic, oxide or solution, and under a variety of spectral conditions, including unmoderated (i.e., bare), metal reflected and water or other light element reflected. Assembly eigenvalues that were accurately predicted with ENDF/B-VII.0 cross sections such as unmoderated and uranium reflected 235U and 239Pu assemblies, HEU solution systems and LEU oxide lattice systems that mimic commercial PWR configurations continue to be accurately calculated with ENDF/B-VII.1 cross sections, and deficiencies in predicted eigenvalues for assemblies containing selected materials, including titanium, manganese, cadmium and tungsten are greatly reduced. Improvements are also confirmed for selected actinide reaction rates such as 236U capture. Other deficiencies, such as the overprediction of Pu solution system critical eigenvalues and a decreasing trend in calculated eigenvalue for

  2. ENDF/B-VII.1 Neutron Cross Section Data Testing with Critical Assembly Benchmarks and Reactor Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kahler, A. [Los Alamos National Laboratory (LANL); Macfarlane, R E [Los Alamos National Laboratory (LANL); Mosteller, R D [Los Alamos National Laboratory (LANL); Kiedrowski, B C [Los Alamos National Laboratory (LANL); Frankle, S C [Los Alamos National Laboratory (LANL); Chadwick, M. B. [Los Alamos National Laboratory (LANL); Mcknight, R D [Argonne National Laboratory (ANL); Lell, R M [Argonne National Laboratory (ANL); Palmiotti, G [Idaho National Laboratory (INL); Hiruta, h [Idaho National Laboratory (INL); Herman, Micheal W [Brookhaven National Laboratory (BNL); Arcilla, r [Brookhaven National Laboratory (BNL); Mughabghab, S F [Brookhaven National Laboratory (BNL); Sublet, J C [Culham Science Center, Abington, UK; Trkov, A. [Jozef Stefan Institute, Slovenia; Trumbull, T H [Knolls Atomic Power Laboratory; Dunn, Michael E [ORNL

    2011-01-01

    The ENDF/B-VII.1 library is the latest revision to the United States' Evaluated Nuclear Data File (ENDF). The ENDF library is currently in its seventh generation, with ENDF/B-VII.0 being released in 2006. This revision expands upon that library, including the addition of new evaluated files (was 393 neutron files previously, now 423 including replacement of elemental vanadium and zinc evaluations with isotopic evaluations) and extension or updating of many existing neutron data files. Complete details are provided in the companion paper [1]. This paper focuses on how accurately application libraries may be expected to perform in criticality calculations with these data. Continuous energy cross section libraries, suitable for use with the MCNP Monte Carlo transport code, have been generated and applied to a suite of nearly one thousand critical benchmark assemblies defined in the International Criticality Safety Benchmark Evaluation Project's International Handbook of Evaluated Criticality Safety Benchmark Experiments. This suite covers uranium and plutonium fuel systems in a variety of forms such as metallic, oxide or solution, and under a variety of spectral conditions, including unmoderated (i.e., bare), metal reflected and water or other light element reflected. Assembly eigenvalues that were accurately predicted with ENDF/B-VII.0 cross sections such as unrnoderated and uranium reflected (235)U and (239)Pu assemblies, HEU solution systems and LEU oxide lattice systems that mimic commercial PWR configurations continue to be accurately calculated with ENDF/B-VII.1 cross sections, and deficiencies in predicted eigenvalues for assemblies containing selected materials, including titanium, manganese, cadmium and tungsten are greatly reduced. Improvements are also confirmed for selected actinide reaction rates such as (236)U; (238,242)Pu and (241,243)Am capture in fast systems. Other deficiencies, such as the overprediction of Pu solution system critical

  3. ENDF/B-VII.1 Neutron Cross Section Data Testing with Critical Assembly Benchmarks and Reactor Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kahler, A.C.; Herman, M.; Kahler,A.C.; MacFarlane,R.E.; Mosteller,R.D.; Kiedrowski,B.C.; Frankle,S.C.; Chadwick,M.B.; McKnight,R.D.; Lell,R.M.; Palmiotti,G.; Hiruta,H.; Herman,M.; Arcilla,R.; Mughabghab,S.F.; Sublet,J.C.; Trkov,A.; Trumbull,T.H.; Dunn,M.

    2011-12-01

    The ENDF/B-VII.1 library is the latest revision to the United States Evaluated Nuclear Data File (ENDF). The ENDF library is currently in its seventh generation, with ENDF/B-VII.0 being released in 2006. This revision expands upon that library, including the addition of new evaluated files (was 393 neutron files previously, now 423 including replacement of elemental vanadium and zinc evaluations with isotopic evaluations) and extension or updating of many existing neutron data files. Complete details are provided in the companion paper [M. B. Chadwick et al., 'ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data,' Nuclear Data Sheets, 112, 2887 (2011)]. This paper focuses on how accurately application libraries may be expected to perform in criticality calculations with these data. Continuous energy cross section libraries, suitable for use with the MCNP Monte Carlo transport code, have been generated and applied to a suite of nearly one thousand critical benchmark assemblies defined in the International Criticality Safety Benchmark Evaluation Project's International Handbook of Evaluated Criticality Safety Benchmark Experiments. This suite covers uranium and plutonium fuel systems in a variety of forms such as metallic, oxide or solution, and under a variety of spectral conditions, including unmoderated (i.e., bare), metal reflected and water or other light element reflected. Assembly eigenvalues that were accurately predicted with ENDF/B-VII.0 cross sections such as unmoderated and uranium reflected {sup 235}U and {sup 239}Pu assemblies, HEU solution systems and LEU oxide lattice systems that mimic commercial PWR configurations continue to be accurately calculated with ENDF/B-VII.1 cross sections, and deficiencies in predicted eigenvalues for assemblies containing selected materials, including titanium, manganese, cadmium and tungsten are greatly reduced. Improvements are also

  4. Coarse-graining polymers with the MARTINI force-field: polystyrene as a benchmark case

    DEFF Research Database (Denmark)

    Rossi, G.; Monticelli, L.; Puisto, S. R.;

    2011-01-01

    in the parameterization. We refine the MARTINI procedure by including one additional target property related to the structure of the polymer, namely the radius of gyration. The force-field optimization is mainly based on experimental data. We test our procedure on polystyrene, a standard benchmark for coarse-grained (CG...

  5. Monte Carlo simulations and benchmark measurements on the response of TE(TE) and Mg(Ar) ionization chambers in photon, electron and neutron beams

    Science.gov (United States)

    Lin, Yi-Chun; Huang, Tseng-Te; Liu, Yuan-Hao; Chen, Wei-Lin; Chen, Yen-Fu; Wu, Shu-Wei; Nievaart, Sander; Jiang, Shiang-Huei

    2015-06-01

    The paired ionization chambers (ICs) technique is commonly employed to determine neutron and photon doses in radiology or radiotherapy neutron beams, where neutron dose shows very strong dependence on the accuracy of accompanying high energy photon dose. During the dose derivation, it is an important issue to evaluate the photon and electron response functions of two commercially available ionization chambers, denoted as TE(TE) and Mg(Ar), used in our reactor based epithermal neutron beam. Nowadays, most perturbation corrections for accurate dose determination and many treatment planning systems are based on the Monte Carlo technique. We used general purposed Monte Carlo codes, MCNP5, EGSnrc, FLUKA or GEANT4 for benchmark verifications among them and carefully measured values for a precise estimation of chamber current from absorbed dose rate of cavity gas. Also, energy dependent response functions of two chambers were calculated in a parallel beam with mono-energies from 20 keV to 20 MeV photons and electrons by using the optimal simple spherical and detailed IC models. The measurements were performed in the well-defined (a) four primary M-80, M-100, M120 and M150 X-ray calibration fields, (b) primary 60Co calibration beam, (c) 6 MV and 10 MV photon, (d) 6 MeV and 18 MeV electron LINACs in hospital and (e) BNCT clinical trials neutron beam. For the TE(TE) chamber, all codes were almost identical over the whole photon energy range. In the Mg(Ar) chamber, MCNP5 showed lower response than other codes for photon energy region below 0.1 MeV and presented similar response above 0.2 MeV (agreed within 5% in the simple spherical model). With the increase of electron energy, the response difference between MCNP5 and other codes became larger in both chambers. Compared with the measured currents, MCNP5 had the difference from the measurement data within 5% for the 60Co, 6 MV, 10 MV, 6 MeV and 18 MeV LINACs beams. But for the Mg(Ar) chamber, the derivations reached 7

  6. Neutronics Benchmarks for the Utilization of Mixed-Oxide Fuel: Joint US/Russian Progress Report for Fiscal 1997. Volume 3 - Calculations Performed in the Russian Federation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-06-01

    This volume of the progress report provides documentation of reactor physics and criticality safety studies conducted in the Russian Federation during fiscal year 1997 and sponsored by the Fissile Materials Disposition Program of the US Department of Energy. Descriptions of computational and experimental benchmarks for the verification and validation of computer programs for neutron physics analyses are included. All benchmarks include either plutonium, uranium, or mixed uranium and plutonium fuels. Calculated physics parameters are reported for all of the contaminated benchmarks that the United States and Russia mutually agreed in November 1996 were applicable to mixed-oxide fuel cycles for light-water reactors.

  7. Weakly bound states of neutrons in gravitational fields

    OpenAIRE

    Khugaev, Avas V.; Sultanov, Renat A.; Guster, Dennis

    2010-01-01

    In this paper a quantum-mechanical behaviour of neutrons in gravitational fields is considered. A first estimation is made using the semiclassical approximation, neglecting General Relativity, magnetic and rotation effects, for neutrons in weakly bound states in the weak gravitational field of the Earth. This result was generalized for a case, in which the Randall - Sundrum correction to Newton's gravitational law on the small scales was applied. Application of the results to Neutron Star phy...

  8. Core management and fast neutron field characterization of JOYO

    International Nuclear Information System (INIS)

    Twenty eight years of operations at the experimental fast reactor JOYO provide a wealth of experience with core management and characterization of fast neutron field. This experience has been applied to several core modifications to upgrade JOYO's irradiation capability. Reactor physics test and neutron n field.flux measurement results have been used to confirm the accuracy of neutron diffusion theory calculations. These experiences and accumulated data will be useful for the core design in future fast reactors. (author)

  9. The Response of Alanine Dosimeters in Thermal Neutron Fields

    OpenAIRE

    Schmitz, T; Bassler, Niels; Sharpe, P; Palmans, H.; KRATZ J.v.; Langgruth, P.; HAMPEL G.

    2012-01-01

    Purpose:Boron Neutron Capture Therapy (BNCT) is a special kind of particle therapy, based on the neutron induced fission of the boron isotope 10B [1]. We have performed dosimetry experiments on the mixed neutron and gamma fields at the TRIGA Mark II research reactor in Mainz. Commonly, dosimetry in such fields is realized by foil activation and ion chambers [2]. Here we investigate alanine as an easier and more robust alternative dosimeter.Methods:We have performed four phantom experiments at...

  10. Status of international benchmark experiment for effective delayed neutron fraction ({beta}eff)

    Energy Technology Data Exchange (ETDEWEB)

    Okajima, S.; Sakurai, T.; Mukaiyama, T. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-03-01

    To improve the prediction accuracy of the {beta}eff, the program of the international benchmark experiment (Beta Effect Reactor Experiment for a New International Collaborative Evaluation: BERNICE) was planned. This program composed of two parts; BERNICE-MASURCA and BERNICE-FCA. The former one was carried out in the fast critical facility MASURCA of CEA, FRANCE between 1993 and 1994. The latter one started in the FCA, JAERI in 1995 and still is going. In these benchmark experiments, various experimental techniques have been applied for in-pile measurements of the {beta}eff. The accuracy of the measurements was better than 3%. (author)

  11. The neutron imaging system fielded at the National Ignition Facility

    International Nuclear Information System (INIS)

    We have fielded a neutron imaging system at the National Ignition Facility to collect images of fusion neutrons produced in the implosion of inertial confinement fusion experiments and scattered neutrons from (n, n') reactions of the source neutrons in the surrounding dense material. A description of the neutron imaging system is presented, including the pinhole array aperture, the line-of-sight collimation, the scintillator-based detection system and the alignment systems and methods. Discussion of the alignment and resolution of the system is presented. We also discuss future improvements to the system hardware. (authors)

  12. The Neutron Imaging System Fielded at the National Ignition Facility

    International Nuclear Information System (INIS)

    We have fielded a neutron imaging system at the National Ignition Facility to collect images of fusion neutrons produced in the implosion of inertial confinement fusion experiments and scattered neutrons from (n, n') reactions of the source neutrons in the surrounding dense material. A description of the neutron imaging system will be presented, including the pinhole array aperture, the line-of-sight collimation, the scintillator-based detection system and the alignment systems and methods. Discussion of the alignment and resolution of the system will be presented. We will also discuss future improvements to the system hardware.

  13. The neutron imaging system fielded at the National Ignition Facility

    Directory of Open Access Journals (Sweden)

    Fittinghoff D.N.

    2013-11-01

    Full Text Available We have fielded a neutron imaging system at the National Ignition Facility to collect images of fusion neutrons produced in the implosion of inertial confinement fusion experiments and scattered neutrons from (n, n′ reactions of the source neutrons in the surrounding dense material. A description of the neutron imaging system is presented, including the pinhole array aperture, the line-of-sight collimation, the scintillator-based detection system and the alignment systems and methods. Discussion of the alignment and resolution of the system is presented. We also discuss future improvements to the system hardware.

  14. Interaction of neutrons with the matter in the laser field

    International Nuclear Information System (INIS)

    The interactions of neutrons with the molecules, atoms and nuclei in the presence of the coherent electromagnetic radiation are considered. There are two effects which are discussed in detail: 1) the ''acceleration'' of thermal neutrons passed through the excited by the resonance laser wave molecular gas; 2) the induced by the laser field the slow neutron capture accompanied by the compound nucleus level excitation. The given effects, if they are experimentally detected, give the possibility to control the neutron flux (spectrum change, polarization, spatial modulation and etc.) and change the interaction cross sections of thermal and resonance neutrons with nuclei due to excitation of p levels of the compound nucleus

  15. Magnetic Fields in neutron stars : A theoretical perspective

    NARCIS (Netherlands)

    Reisenegger, A.; Prieto, J.; Benguria, R.; Lai, D.; Araya, P.

    2005-01-01

    Abstract: We present our view of the main physical ingredients determining the evolution of neutron star magnetic fields. This includes the basic properties of neutron star matter, possible scenarios for the origin of the magnetic field, constraints and mechanisms for its evolution, and a discussion

  16. MOX use in reactors: Benchmarking of neutronic codes -- Analyses of selected Saxton plutonium program experiments using WIMS7a

    Energy Technology Data Exchange (ETDEWEB)

    Cuevas Vivas, G.F.; Paris, T.A. [Texas A and M Univ., College Station, TX (United States)

    1999-03-01

    As part of the effort for the benchmarking neutronic codes for plutonium utilization, the deterministic code WIMS7a (and its associated JEF 2.2 nuclear data library) was employed to calculationally model a selected group of the Saxton experiments. The selection of the experimental configurations to be modeled was performed based on the best experimental information available, and so as to fully exploit the neutronic variety of the Saxton plutonium program experiments. The modular WIMS7a code can be run in many ways. For the analyses presented here, a solver strategy was implemented using WIMS7a`s most evolved modules. The results showed a slightly better agreement with the experimental values for the effective neutron multiplication than the earlier results (obtained in 1997) using the codes, WIMSD4m and DIF3D. However, the calculated relative rod power distributions were not improved even though several energy group structures were tried. The simulations were carried out at Texas A and M University with access to WIMS7a being obtained via a one year lease from the AEA Technology.

  17. The Verification of Coupled Neutronics Thermal-Hydraulics Code NODAL3 in the PWR Rod Ejection Benchmark

    Directory of Open Access Journals (Sweden)

    Surian Pinem

    2014-01-01

    Full Text Available A coupled neutronics thermal-hydraulics code NODAL3 has been developed based on the few-group neutron diffusion equation in 3-dimensional geometry for typical PWR static and transient analyses. The spatial variables are treated by using a polynomial nodal method while for the neutron dynamic solver the adiabatic and improved quasistatic methods are adopted. In this paper we report the benchmark calculation results of the code against the OECD/NEA CRP PWR rod ejection cases. The objective of this work is to determine the accuracy of NODAL3 code in analysing the reactivity initiated accident due to the control rod ejection. The NEACRP PWR rod ejection cases are chosen since many organizations participated in the NEA project using various methods as well as approximations, so that, in addition to the reference solutions, the calculation results of NODAL3 code can also be compared to other codes’ results. The transient parameters to be verified are time of power peak, power peak, final power, final average Doppler temperature, maximum fuel temperature, and final coolant temperature. The results of NODAL3 code agree well with the PHANTHER reference solutions in 1993 and 1997 (revised. Comparison with other validated codes, DYN3D/R and ANCK, shows also a satisfactory agreement.

  18. Monte Carlo simulations and benchmark measurements on the response of TE(TE) and Mg(Ar) ionization chambers in photon, electron and neutron beams

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yi-Chun [Health Physics Division, Institute of Nuclear Energy Research, Taoyuan County, Taiwan (China); Huang, Tseng-Te, E-mail: huangtt@iner.gov.tw [Health Physics Division, Institute of Nuclear Energy Research, Taoyuan County, Taiwan (China); Liu, Yuan-Hao [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu City, Taiwan (China); Chen, Wei-Lin [Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu City, Taiwan (China); Chen, Yen-Fu [Atomic Energy Council, New Taipei City, Taiwan (China); Wu, Shu-Wei [Dept. of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan (China); Nievaart, Sander [Institute for Energy, Joint Research Centre, European Commission, Petten (Netherlands); Jiang, Shiang-Huei [Dept. of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan (China)

    2015-06-01

    The paired ionization chambers (ICs) technique is commonly employed to determine neutron and photon doses in radiology or radiotherapy neutron beams, where neutron dose shows very strong dependence on the accuracy of accompanying high energy photon dose. During the dose derivation, it is an important issue to evaluate the photon and electron response functions of two commercially available ionization chambers, denoted as TE(TE) and Mg(Ar), used in our reactor based epithermal neutron beam. Nowadays, most perturbation corrections for accurate dose determination and many treatment planning systems are based on the Monte Carlo technique. We used general purposed Monte Carlo codes, MCNP5, EGSnrc, FLUKA or GEANT4 for benchmark verifications among them and carefully measured values for a precise estimation of chamber current from absorbed dose rate of cavity gas. Also, energy dependent response functions of two chambers were calculated in a parallel beam with mono-energies from 20 keV to 20 MeV photons and electrons by using the optimal simple spherical and detailed IC models. The measurements were performed in the well-defined (a) four primary M-80, M-100, M120 and M150 X-ray calibration fields, (b) primary {sup 60}Co calibration beam, (c) 6 MV and 10 MV photon, (d) 6 MeV and 18 MeV electron LINACs in hospital and (e) BNCT clinical trials neutron beam. For the TE(TE) chamber, all codes were almost identical over the whole photon energy range. In the Mg(Ar) chamber, MCNP5 showed lower response than other codes for photon energy region below 0.1 MeV and presented similar response above 0.2 MeV (agreed within 5% in the simple spherical model). With the increase of electron energy, the response difference between MCNP5 and other codes became larger in both chambers. Compared with the measured currents, MCNP5 had the difference from the measurement data within 5% for the {sup 60}Co, 6 MV, 10 MV, 6 MeV and 18 MeV LINACs beams. But for the Mg(Ar) chamber, the derivations

  19. Personnel neutron dose assessment upgrade: Volume 2, Field neutron spectrometer for health physics applications

    International Nuclear Information System (INIS)

    Both the (ICRP) and the (NCPR) have recommended an increase in neutron quality factors and the adoption of effective dose equivalent methods. The series of reports entitled Personnel Neutron Dose Assessment Upgrade (PNL-6620) addresses these changes. Volume 1 in this series of reports (Personnel Neutron Dosimetry Assessment) provided guidance on the characteristics, use, and calibration of personnel neutron dosimeters in order to meet the new recommendations. This report, Volume 2: Field Neutron Spectrometer for Health Physics Applications describes the development of a portable field spectrometer which can be set up for use in a few minutes by a single person. The field spectrometer described herein represents a significant advance in improving the accuracy of neutron dose assessment. It permits an immediate analysis of the energy spectral distribution associated with the radiation from which neutron quality factor can be determined. It is now possible to depart from the use of maximum Q by determining and realistically applying a lower Q based on spectral data. The field spectrometer is made up of two modules: a detector module with built-in electronics and an analysis module with a IBM PC/reg sign/-compatible computer to control the data acquisition and analysis of data in the field. The unit is simple enough to allow the operator to perform spectral measurements with minimal training. The instrument is intended for use in steady-state radiation fields with neutrons energies covering the fission spectrum range. The prototype field spectrometer has been field tested in plutonium processing facilities, and has been proven to operate satisfactorily. The prototype field spectrometer uses a 3He proportional counter to measure the neutron energy spectrum between 50 keV and 5 MeV and a tissue equivalent proportional counter (TEPC) to measure absorbed neutron dose

  20. Rotating proto-neutron stars under strong magnetic fields

    CERN Document Server

    Franzon, B; Schramm, S

    2016-01-01

    In this work, we study the effects of magnetic fields and rotation on the structure and composition of proto-neutron stars (PNSs). A hadronic chiral SU(3) model is applied to cold neutron stars (NS) and proto-neutron stars with trapped neutrinos and at fixed entropy per baryon. We obtain general relativistic solutions for neutron and proto-neutron stars endowed with a poloidal magnetic field by solving Einstein-Maxwell field equations in a self-consistent way. As the neutrino chemical potential decreases in value over time, this alters the chemical equilibrium and the composition inside the star, leading to a change in the structure and in the particle population of these objects. We find that the magnetic field deforms the star and significantly alters the number of trapped neutrinos in the stellar interior, together with strangeness content and temperature in each evolution stage.

  1. Energy of Gravitational Field of Static Spherically Symmetric Neutron Stars

    Institute of Scientific and Technical Information of China (English)

    WEN De-Hua; CHEN Wei; WANG Xian-Ju; AI Bao-Quan; LIU Guo-Tao; LIU Liang-Gang

    2003-01-01

    By using the Einstein-Tolman expression of the energy-momentum pseudo-tensor, the energy density ofthe gravitational field of the static spherically symmetric neutron stars is calculated in the Cartesian coordinate system.It is exciting that the energy density of gravitational field is positive and rational. The numerical results ot the energydensity of gravitational field of neutron stars are calculated. For neutron stars with M = 2M , the ratio of the energydensity of gravitational field to the energy density of pure matters would be up to 0.54 at the surface.

  2. Energy of Gravitational Field of Static Spherically Symmetric Neutron Stars

    Institute of Scientific and Technical Information of China (English)

    WENDe-Hua; CHENWei; WANGXian-Ju; AIBao-Quan; LIUGuo-Tao; LIULiang-Gang

    2003-01-01

    By using the Einstein-Tolman expression of the energy-momentum pseudo-tensor, the energy density of the gravitational field of the static spherically symmetric neutron stars is calculated in the Cartesian coordinate system.It is exciting that the energy density of gravitational field is positive and rational The xmmerical results of the energy density of gravitational field of neutron stars are calculated. For neutron stars with M=2M, the ratio of the energy density of gravitational field to the energy density of pure matters would be up to 0.54 at the surface.

  3. A critical assembly designed to measure neutronic benchmarks in support of the space nuclear thermal propulsion program

    Science.gov (United States)

    Parma, Edward J.; Ball, Russell M.; Hoovler, Gary S.; Selcow, Elizabeth C.; Cerbone, Ralph J.

    1993-01-01

    A reactor designed to perform criticality experiments in support of the Space Nuclear Thermal Propulsion program is currently in operation at the Sandia National Laboratories' reactor facility. The reactor is a small, water-moderated system that uses highly enriched uranium particle fuel in a 19-element configuration. Its purpose is to obtain neutronic measurements under a variety of experimental conditions that are subsequently used to benchmark rector-design computer codes. Brookhaven National Laboratory, Babcock & Wilcox, and Sandia National Laboratories participated in determining the reactor's performance requirements, design, follow-on experimentation, and in obtaining the licensing approvals. Brookhaven National Laboratory is primarily responsible for the analytical support, Babcock & Wilcox the hardware design, and Sandia National Laboratories the operational safety. All of the team members participate in determining the experimentation requirements, performance, and data reduction. Initial criticality was achieved in October 1989. An overall description of the reactor is presented along with key design features and safety-related aspects.

  4. Development and benchmark of high energy continuous-energy neutron cross Section library HENDL-ADS/MC

    International Nuclear Information System (INIS)

    The ADS (accelerator driven sub-critical system) has great energy spans, complex energy spectrum structures and strong physical effects. Hence, the existing nuclear data libraries can't fully meet the needs of nuclear analysis in ADS. In order to do nuclear analysis for ADS system, a point-wise data library HENDL-ADS/MC (hybrid evaluated nuclear data library) was produced by FDS team. Meanwhile, to test the availability and reliability of the HENDL-ADS/MC data library, a series of shielding and critical safety benchmarks were performed. To validate and qualify the reliability of the high-energy cross section for HENDL-ADS/MC library further, a series of high neutronics integral experiments have been performed. The testing results confirm the accuracy and reliability of HENDL-ADS/MC. (authors)

  5. Ionization signals from diamond detectors in fast-neutron fields

    Science.gov (United States)

    Weiss, C.; Frais-Kölbl, H.; Griesmayer, E.; Kavrigin, P.

    2016-09-01

    In this paper we introduce a novel analysis technique for measurements with single-crystal chemical vapor deposition (sCVD) diamond detectors in fast-neutron fields. This method exploits the unique electronic property of sCVD diamond sensors that the signal shape of the detector current is directly proportional to the initial ionization profile. In fast-neutron fields the diamond sensor acts simultaneously as target and sensor. The interaction of neutrons with the stable isotopes 12 C and 13 C is of interest for fast-neutron diagnostics. The measured signal shapes of detector current pulses are used to identify individual types of interactions in the diamond with the goal to select neutron-induced reactions in the diamond and to suppress neutron-induced background reactions as well as γ-background. The method is verified with experimental data from a measurement in a 14.3 MeV neutron beam at JRC-IRMM, Geel/Belgium, where the 13C(n, α)10Be reaction was successfully extracted from the dominating background of recoil protons and γ-rays and the energy resolution of the 12C(n, α)9Be reaction was substantially improved. The presented analysis technique is especially relevant for diagnostics in harsh radiation environments, like fission and fusion reactors. It allows to extract the neutron spectrum from the background, and is particularly applicable to neutron flux monitoring and neutron spectroscopy.

  6. Simulation analysis of radiation fields inside phantoms for neutron irradiation

    International Nuclear Information System (INIS)

    Radiation fields inside phantoms have been calculated for neutron irradiation. Particle and heavy-ion transport code system PHITS was employed for the calculation. Energy and size dependences of neutron dose were analyzed using tissue equivalent spheres of different size. A voxel phantom of mouse was developed based on CT images of an 8-week-old male C3H/HeNs mouse. Deposition energy inside the mouse was calculated for 2- and 10-MeV neutron irradiation. (author)

  7. Status of benchmark calculations of the neutron characteristics of the cascade molten salt ADS for the nuclear waste incineration

    Energy Technology Data Exchange (ETDEWEB)

    Dudnikov, A.A.; Alekseev, P.N.; Subbotin, S.A.; Vasiliev, A.V.; Abagyan, L.P.; Alexeyev, N.I.; Gomin, E.A.; Ponomarev, L.I.; Kolyaskin, O.E.; Men' shikov, L.I. [Russian Research Centre Kurchatov Inst., Moscow (Russian Federation); Kolesov, V.F.; Ivanin, I.A.; Zavialov, N.V. [Russian Federal Nuclear Center, RFNC-VNIIEF, Nizhnii Novgorod region (Russian Federation)

    2001-07-01

    The facility for incineration of long-lived minor actinides and some dangerous fission products should be an important feature of the future nuclear power (NP). For many reasons the liquid-fuel reactor driven by accelerator can be considered as the perspective reactor- burner for radioactive waste. The fuel of such reactor is the fluoride molten salt composition with minor actinides (Np, Cm, Am) and some fission products ({sup 99}Tc, {sup 129}I, etc.). Preliminary analysis shows that the values of keff, calculated with different codes and nuclear data differ up to several percents for such fuel compositions. Reliable critical and subcritical benchmark experiments with molten salt fuel compositions with significant quantities of minor actinides are absent. One of the main tasks for the numerical study of this problem is the estimation of nuclear data for such fuel compositions and verification of the different numerical codes used for the calculation of keff, neutron spectra and reaction rates. It is especially important for the resonance region where experimental data are poor or absent. The calculation benchmark of the cascade subcritical molten salt reactor is developed. For the chosen nuclear fuel composition the comparison of the results obtained by three different Monte-Carlo codes (MCNP4A, MCU, and C95) using three different nuclear data libraries are presented. This report concerns the investigation of subcritical molten salt reactor unit main peculiarities carried out at the beginning of ISTC project 1486. (author)

  8. Status of benchmark calculations of the neutron characteristics of the cascade molten salt ADS for the nuclear waste incineration

    International Nuclear Information System (INIS)

    The facility for incineration of long-lived minor actinides and some dangerous fission products should be an important feature of the future nuclear power (NP). For many reasons the liquid-fuel reactor driven by accelerator can be considered as the perspective reactor- burner for radioactive waste. The fuel of such reactor is the fluoride molten salt composition with minor actinides (Np, Cm, Am) and some fission products (99Tc, 129I, etc.). Preliminary analysis shows that the values of keff, calculated with different codes and nuclear data differ up to several percents for such fuel compositions. Reliable critical and subcritical benchmark experiments with molten salt fuel compositions with significant quantities of minor actinides are absent. One of the main tasks for the numerical study of this problem is the estimation of nuclear data for such fuel compositions and verification of the different numerical codes used for the calculation of keff, neutron spectra and reaction rates. It is especially important for the resonance region where experimental data are poor or absent. The calculation benchmark of the cascade subcritical molten salt reactor is developed. For the chosen nuclear fuel composition the comparison of the results obtained by three different Monte-Carlo codes (MCNP4A, MCU, and C95) using three different nuclear data libraries are presented. This report concerns the investigation of subcritical molten salt reactor unit main peculiarities carried out at the beginning of ISTC project 1486. (author)

  9. US/JAERI fusion neutronics calculational benchmarks for nuclear data and codes intercomparison

    International Nuclear Information System (INIS)

    The US Department of Energy (DOE) and the Japan Atomic Energy Research Institute (JAERI) have been involved in a collaborative research program on fusion neutronics. The program focuses on performing post- and pre-analyses for the integral experiments conducted at the fusion neutronics source (FNS) facility at JAERI. The main general objectives of the program are: (a) to provide experimental data needed to determine the accuracy, guide the development and establish the validity of computational methods and the nuclear data base; (b) to provide the data base required to evaluate the overall uncertainty (both analytical and experimental) in estimating key parameters of importance in fusion blanket design (e.g., tritium production rate, nuclear heating rate, dose rate, etc.); (c) to intercompare various measuring techniques and to increase the reliability of measurements by developing more advanced detectors; (d) to provide experimental data to assist in the selection of materials and configuration of candidate blanket concepts from the neutronics viewpoint

  10. Magnetic structure determination using zero-field neutron polarimetry

    International Nuclear Information System (INIS)

    A simple interpretation of the formulae which predict the polarisation of elastically scattered neutrons and a pictorial representation of the polarisation directions before and after the scattering process are presented. Some results from recent zero-field neutron polarimetry experiments are used to demonstrate the theory. (orig.)

  11. TRIPOLI-2: neutron gamma coupling - applications to shielding benchmarks and designs

    Energy Technology Data Exchange (ETDEWEB)

    Cramer, S.N.; Dejonghe, G.; Gonnord, J.; Nimal, J.C.; Vergnaud, T.

    1983-05-01

    Recent additions in the on-going development of the TRIPOLI Monte Carlo code system include conversion to the ENDF/B data format and an automated coupling scheme for neutron secondary gamma-ray calculations. Two shielding calculations are presented here which feature these two new developments.

  12. Measurement of accelerator neutron radiation field spectrum by Extended Range Neutron Multisphere Spectrometers and unfolding program

    CERN Document Server

    Li, Guanjia; Ma, Zhongjian; Guo, Siming; Yan, Mingyang; Shi, Haoyu; Xu, Chao

    2015-01-01

    This paper described a measurement of accelerator neutron radiation field at a transport beam line of Beijing-TBF. The experiment place was be selected around a Faraday Cup with a graphite target impacted by electron beam at 2.5GeV. First of all, we simulated the neutron radiation experiment by FLUKA. Secondly, we chose six appropriate ERNMS according to their neutron fluence response function to measure the neutron count rate. Then the U_M_G package program was be utilized to unfolding experiment data. Finally, we drew a comparison between the unfolding with the simulation spectrum and made an analysis about the result.

  13. Reference neutron fields for metrology of radiation monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Aleinikov, V.E.; Bamblevskij, V.P.; Komochkov, M.M.; Krylov, A.R.; Mokrov, Yu.V.; Timoshenko, G.N. (Joint Inst. for Nuclear Research, Dubna (Russian Federation))

    1994-01-01

    A set of reference neutron fields has been created in the Joint Institute for Nuclear Research for metrology of radiation monitoring. The set covers the common energy range of neutrons generated by nuclear installations of the Institute (from [approx] 10[sup -8] to hundreds of MeV). The set comprises reference fields based on [sup 252]Cf in polyethylene moderators with diameters 12.7 and 29.2 cm and two reference fields, based on a 600 MeV phasotron. A soft field is created in the labyrinth of the phasotron by scattered neutrons. A hard field is formed by leakage neutrons from a concrete shield without holes. This shield is irradiated by secondary radiation produced in the accelerator chamber and the target station. (author).

  14. Reference neutron fields for metrology of radiation monitoring

    International Nuclear Information System (INIS)

    A set of reference neutron fields has been created in the Joint Institute for Nuclear Research for metrology of radiation monitoring. The set covers the common energy range of neutrons generated by nuclear installations of the Institute (from ∼ 10-8 to hundreds of MeV). The set comprises reference fields based on 252Cf in polyethylene moderators with diameters 12.7 and 29.2 cm and two reference fields, based on a 600 MeV phasotron. A soft field is created in the labyrinth of the phasotron by scattered neutrons. A hard field is formed by leakage neutrons from a concrete shield without holes. This shield is irradiated by secondary radiation produced in the accelerator chamber and the target station. (author)

  15. Evaluation of neutron radiation field in carbon ion therapy

    Science.gov (United States)

    Xu, Jun-Kui; Su, You-Wu; Li, Wu-Yuan; Yan, Wei-Wei; Chen, Xi-Meng; Mao, Wang; Pang, Cheng-Guo

    2016-01-01

    Carbon ions have significant advantages in tumor therapy because of their physical and biological properties. In view of the radiation protection, the safety of patients is the most important issue in therapy processes. Therefore, the effects of the secondary particles produced by the carbon ions in the tumor therapy should be carefully considered, especially for the neutrons. In the present work, the neutron radiation field induced by carbon ions was evaluated by using the FLUKA code. The simulated results of neutron energy spectra and neutron dose was found to be in good agreement with the experiment data. In addition, energy deposition of carbon ions and neutrons in tissue-like media was studied, it is found that the secondary neutron energy deposition is not expected to exceed 1% of the carbon ion energy deposition in a typical treatment.

  16. Study on neutron radiation field of carbon ions therapy

    CERN Document Server

    Xu, Jun-Kui; Li, Wu-Yuan; Yan, Wei-Wei; Chen, Xi-Meng; Mao, Wang; Pang, Cheng-Guo

    2015-01-01

    Carbon ions offer significant advantages for deep-seated local tumors therapy due to their physical and biological properties. Secondary particles, especially neutrons caused by heavy ion reactions should be carefully considered in treatment process and radiation protection. For radiation protection purposes, the FLUKA Code was used in order to evaluate the radiation field at deep tumor therapy room of HIRFL in this paper. The neutron energy spectra, neutron dose and energy deposition of carbon ion and neutron in tissue-like media was studied for bombardment of solid water target by 430MeV/u C ions. It is found that the calculated neutron dose have a good agreement with the experimental date, and the secondary neutron dose may not exceed one in a thousand of the carbon ions dose at Bragg peak area in tissue-like media.

  17. Computational evaluation oa a neutron field facility

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Jose Julio de O.; Pazianotto, Mauricio T., E-mail: jjfilos@hotmail.com, E-mail: mpazianotto@gmail.com [Instituto Tecnologico de Aeronautica (ITA/DCTA), Sao Jose dos Campos, SP (Brazil); Federico, Claudio A.; Passaro, Angelo, E-mail: claudiofederico@ieav.cta.br, E-mail: angelo@ieav.cta.br [Instituto de Estudos Avancados (IEAv/DCTA), Sao Jose dos Campos, SP (Brazil)

    2015-07-01

    This paper describes the results of a study based on computer simulation for a realistic 3D model of Ionizing Radiation Laboratory of the Institute for Advanced Studies (IEAv) using the MCNP5 (Monte Carlo N-Particle) code, in order to guide the installing a neutron generator, produced by reaction {sup 3}H(d,n){sup 4}He. The equipment produces neutrons with energy of 14.1 MeV and 2 x 10{sup 8} n/s production rate in 4 πgeometry, which can also be used for neutron dosimetry studies. This work evaluated the spectra and neutron fluence provided on previously selected positions inside the facility, chosen due to the interest to evaluate the assessment of ambient dose equivalent so that they can be made the necessary adjustments to the installation to be consistent with the guidelines of radiation protection and radiation safety, determined by the standards of National Nuclear Energy Commission (CNEN). (author)

  18. Evaluation of thermal neutron irradiation field using a cyclotron-based neutron source for alpha autoradiography

    International Nuclear Information System (INIS)

    It is important to measure the microdistribution of 10B in a cell to predict the cell-killing effect of new boron compounds in the field of boron neutron capture therapy. Alpha autoradiography has generally been used to detect the microdistribution of 10B in a cell. Although it has been performed using a reactor-based neutron source, the realization of an accelerator-based thermal neutron irradiation field is anticipated because of its easy installation at any location and stable operation. Therefore, we propose a method using a cyclotron-based epithermal neutron source in combination with a water phantom to produce a thermal neutron irradiation field for alpha autoradiography. This system can supply a uniform thermal neutron field with an intensity of 1.7×109 (cm−2 s−1) and an area of 40 mm in diameter. In this paper, we give an overview of our proposed system and describe a demonstration test using a mouse liver sample injected with 500 mg/kg of boronophenyl-alanine. - Highlights: • We developed a thermal neutron irradiation field using cyclotron based epithermal neutron source combination with a water phantom for alpha autoradiography. • The uniform thermal neutron irradiation field with an intensity of 1.7×109 (cm−2 s−1) with a size of 40 mm in diameter was obtained. • Demonstration test of alpha autoradiography using a liver sample with the injection of BPA was performed. • Boron image discriminated with the background event of protons was clearly shown by means of the particle identification

  19. Neutron Limit on the Strongly-Coupled Chameleon Field

    CERN Document Server

    Li, K; Cory, D G; Haun, R; Heacock, B; Huber, M G; Nsofini, J; Pushin, D A; Saggu, P; Sarenac, D; Shahi, C B; Skavysh, V; Snow, W M; Young, A R

    2016-01-01

    The physical origin of the dark energy that causes the accelerated expansion rate of the universe is one of the major open questions of cosmology. One set of theories postulates the existence of a self-interacting scalar field for dark energy coupling to matter. In the chameleon dark energy theory, this coupling induces a screening mechanism such that the field amplitude is nonzero in empty space but is greatly suppressed in regions of terrestrial matter density. However measurements performed under appropriate vacuum conditions can enable the chameleon field to appear in the apparatus, where it can be subjected to laboratory experiments. Here we report the most stringent upper bound on the free neutron-chameleon coupling in the strongly-coupled limit of the chameleon theory using neutron interferometric techniques. Our experiment sought the chameleon field through the relative phase shift it would induce along one of the neutron paths inside a perfect crystal neutron interferometer. The amplitude of the cham...

  20. A Neutronics Solution to the OECD/NEA/NSC PBMR-400 Stand Alone Steady State Benchmark Problem by using the Hex-Z Solver of the MASTER Code

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Chul; Song, Jae Seung; Noh, Jae Man [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2006-07-01

    Recently, the OECD/NEA/NSC PBMR-400 coupled neutronics/thermal hydraulics transient benchmark problem was proposed. The benchmark problem was derived from the design data of the PBMR-400 nuclear power plant. The benchmark problem consists of two phases. Phase I is a steady state which consists of three exercises. Phase II is the transient state initiated from phase I. Exercise 1 and exercise 2 of phase I are stand alone steady state problems for the neutronics and thermal hydraulics, respectively. Exercise 3 is a couple neutronics/thermal hydraulics steady state problem, which is the initial condition for the phase II problems. In this paper, we present a solution to the exercise 1 of phase I of the benchmark problem by using the MASTER code. Although the original problem is defined as an R-Z 2D problem, we transformed it into an approximate 3D problem which consists of many hexagonal prisms. The approximate 3D problem was then solved by using the Hex- Z solver of the MASTER code. To investigate the effect of the geometrical approximation, the solution of the MASTER code was compared with a reference finite difference method (FDM) solution for the original problem.

  1. Neutron Star Magnetic Field as for Nonzero Photon Mass

    Institute of Scientific and Technical Information of China (English)

    WANG Qing-Wu; L(U) Xiao-Fu

    2005-01-01

    We investigate the neutron star magnetic field by the relative mean-field theory, where the photon effective mass depending on baryon density of charged particles is nonzero. This field is produced by star itself, which is the function of baryon density. The result fits the observations.

  2. Reference neutron fields for metrology of radiation monitoring

    International Nuclear Information System (INIS)

    The set of reference neutron fields created in the JINR for metrology of radiation monitoring is described. The set comprises reference fields based on Cf-252 in polyethylene moderators with diameters 12.7 cm and 29.2 cm and two reference fields based on 660 MeV Laboratory of Nuclear Problems phasotron. 11 refs.; 7 figs.; 1 tab

  3. Producing ultrastrong magnetic fields in neutron star mergers.

    Science.gov (United States)

    Price, D J; Rosswog, S

    2006-05-01

    We report an extremely rapid mechanism for magnetic field amplification during the merger of a binary neutron star system. This has implications for the production of the short class of gamma-ray bursts, which recent observations suggest may originate in such mergers. In detailed magnetohydrodynamic simulations of the merger process, the fields are amplified by Kelvin-Helmholtz instabilities beyond magnetar field strength and may therefore represent the strongest magnetic fields in the universe. The amplification occurs in the shear layer that forms between the neutron stars and on a time scale of only 1 millisecond, that is, long before the remnant can collapse into a black hole.

  4. Thermal evolution of neutron stars with decaying magnetic fields

    International Nuclear Information System (INIS)

    Rotochemical heating originates in the deviation from beta equilibrium due to spin-down compression, which is closely related to the dipole magnetic field. We numerically calculate the deviation from chemical equilibrium and thermal evolution of neutron stars with decaying magnetic fields. We find that the power-law long term decay of the magnetic field slightly affects the deviation from chemical equilibrium and surface temperature. However, the magnetic decay leads to older neutron stars that could have a different surface temperature with the same magnetic field strength. That is, older neutron stars with a low magnetic field (108 G) could have a lower temperature even with rotochemical heating in operation, which probably explains the lack of other observations on older millisecond pulsars with higher surface temperature, except millisecond pulsar J0437–4715. (paper)

  5. A benchmark analysis of radiation flux distribution for Boron Neutron Capture Therapy of canine brain tumors

    Energy Technology Data Exchange (ETDEWEB)

    Moran, J.M.

    1992-02-01

    Calculations of radiation flux and dose distributions for Boron Neutron Capture Therapy (BNCT) of brain tumors are typically performed using sophisticated three-dimensional analytical models based on either a homogeneous approximation or a simplified few-region approximation to the actual highly-heterogeneous geometry of the irradiation volume. Such models should be validated by comparison with calculations using detailed models in which all significant macroscopic tissue heterogeneities and geometric structures are explicitly represented as faithfully as possible. This work describes a validation exercise for BNCT of canine brain tumors. Geometric measurements of the canine anatomical structures of interest for this work were performed by dissecting and examining two essentially identical Labrador Retriever heads. Chemical analyses of various tissue samples taken during the dissections were conducted to obtain measurements of elemental compositions for tissues of interest. The resulting geometry and tissue composition data were then used to construct a detailed heterogeneous calculational model of the Labrador Retriever head. Calculations of three-dimensional radiation flux distributions pertinent to BNCT were performed for the model using the TORT discrete-ordinates radiation transport code. The calculations were repeated for a corresponding volume-weighted homogeneous tissue model. Comparison of the results showed that the peak neutron and photon flux magnitudes were quite similar for the two models (within 5%), but that the spatial flux profiles were shifted in the heterogeneous model such that the fluxes in some locations away from the peak differed from the corresponding fluxes in the homogeneous model by as much as 10-20%. Differences of this magnitude can be therapeutically significant, emphasizing the need for proper validation of simplified treatment planning models.

  6. A benchmark analysis of radiation flux distribution for Boron Neutron Capture Therapy of canine brain tumors

    International Nuclear Information System (INIS)

    Calculations of radiation flux and dose distributions for Boron Neutron Capture Therapy (BNCT) of brain tumors are typically performed using sophisticated three-dimensional analytical models based on either a homogeneous approximation or a simplified few-region approximation to the actual highly-heterogeneous geometry of the irradiation volume. Such models should be validated by comparison with calculations using detailed models in which all significant macroscopic tissue heterogeneities and geometric structures are explicitly represented as faithfully as possible. This work describes a validation exercise for BNCT of canine brain tumors. Geometric measurements of the canine anatomical structures of interest for this work were performed by dissecting and examining two essentially identical Labrador Retriever heads. Chemical analyses of various tissue samples taken during the dissections were conducted to obtain measurements of elemental compositions for tissues of interest. The resulting geometry and tissue composition data were then used to construct a detailed heterogeneous calculational model of the Labrador Retriever head. Calculations of three-dimensional radiation flux distributions pertinent to BNCT were performed for the model using the TORT discrete-ordinates radiation transport code. The calculations were repeated for a corresponding volume-weighted homogeneous tissue model. Comparison of the results showed that the peak neutron and photon flux magnitudes were quite similar for the two models (within 5%), but that the spatial flux profiles were shifted in the heterogeneous model such that the fluxes in some locations away from the peak differed from the corresponding fluxes in the homogeneous model by as much as 10-20%. Differences of this magnitude can be therapeutically significant, emphasizing the need for proper validation of simplified treatment planning models

  7. Benchmarks on effective delayed neutron parameters and reactivity: a Brazilian IPEN/MB-01 contribution to the IRPhE project

    Energy Technology Data Exchange (ETDEWEB)

    Dos Santos, Adimir; Yoichi Ribeiro Kuramoto, Renato; Diniz, Ricardo; Jereza Graciete Simoes de Andrade e Silva, Rogerio; Yamaguchi, Mitsuo [Instituto de Pesquisas Energeticas e Nucleares, IPEN - CNEN/SP, Sao Paulo (Brazil)

    2008-07-01

    The purpose of this work is to present the experimental results of the in-pile experiments performed at the IPEN/MB-01 Reactor for the determination of the effective delayed neutron parameters and reactivity. The methodologies employed were the macroscopic noise in the frequency domain, where the very low frequency range (< 1.0 Hz) was also exploited and analyzed, and the microscopic noise, which is based on the measurement of Rossi-alpha and Feynmann-alpha distributions at several subcritical levels. In this last case, a Two- Region Model was developed. The main advantage of these methodologies is to obtain the effective delayed neutron parameters in a purely experimental way, eliminating all parameters that are difficult to measure or calculate. Consequently, the uncertainties associated with these parameters are eliminated and the accuracy in the effective delayed neutron parameters is improved. Both techniques are claimed to be well defined and produce experimental data of very high quality. Finally, it is proposed to assign benchmark-values to beta{sub eff} (the effective delayed neutron fraction), to LAMBDA (the prompt neutron generation time), to their ratio (beta{sub eff}/LAMBDA) and also for the first time to the reactivity by means of the in-hour equation. It is concluded that the experiments are acceptable benchmarks. (authors)

  8. The freedom to choose neutron star magnetic field equilibria

    OpenAIRE

    Glampedakis, Kostas; Lasky, Paul D.

    2016-01-01

    Our ability to interpret and glean useful information from the large body of observations of strongly magnetised neutron stars rests largely on our theoretical understanding of magnetic field equilibria. We answer the following question: is one free to arbitrarily prescribe magnetic equilibria such that fluid degrees of freedom can balance the equilibrium equations? We examine this question for various models for neutron star matter; from the simplest single-fluid barotrope to more realistic ...

  9. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    Energy Technology Data Exchange (ETDEWEB)

    Caresana, M., E-mail: marco.caresana@polimi.it [Politecnico di Milano, CESNEF, Dipartimento di Energia, via Ponzio 34/3, 20133 Milano (Italy); Denker, A. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Esposito, A. [IFNF-LNF, FISMEL, via E. Fermi 40, 00044 Frascati (Italy); Ferrarini, M. [CNAO, Via Privata Campeggi, 27100 Pavia (Italy); Golnik, N. [Institute of Metrology and Biomedical Engineering, Warsaw University of Technology, Sw. A. Boboli 8, 02-525 Warsaw (Poland); Hohmann, E. [Paul Scherrer Institut (PSI), Radiation Metrology Section, CH-5232 Villigen PSI (Switzerland); Leuschner, A. [Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg (Germany); Luszik-Bhadra, M. [Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig (Germany); Manessi, G. [CERN, 1211 Geneva 23 (Switzerland); University of Liverpool, Department of Physics, L69 7ZE Liverpool (United Kingdom); Mayer, S. [Paul Scherrer Institut (PSI), Radiation Metrology Section, CH-5232 Villigen PSI (Switzerland); Ott, K. [Helmholtz-Zentrum Berlin, BESSYII, Albert-Einstein-Str.15, 12489 Berlin (Germany); Röhrich, J. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Silari, M. [CERN, 1211 Geneva 23 (Switzerland); Trompier, F. [Institute for Radiological Protection and Nuclear Safety, F-92262 Fontenay aux Roses (France); Volnhals, M.; Wielunski, M. [Helmholtz Zentrum München, Ingolstädter Landstr. 1, D-85764 Neuherberg (Germany)

    2014-02-11

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instruments were placed in a reference position and irradiated with neutrons delivered in bursts of different intensity. The analysis of the instrument response as a function of the burst charge (the total electric charge of the protons in the burst shot onto the tungsten target) permitted to assess for each device the dose underestimation due to the time structure of the radiation field. The personal neutron dosemeters were exposed on a standard PMMA slab phantom and the response linearity was evaluated.

  10. Calibration of a special neutron dosemeter based on solid-state track detectors and fission radiators in various neutron fields

    International Nuclear Information System (INIS)

    The calibration of a personnel neutron dosemeter in different neutron fields is described. The badge-like dosemeter contains 5 detectors: polycarbonate foil (10 μm, Makrofol KG), 232Th, natural uranium, natural uranium with boron, and natural uranium with cadmium. Detector sensitivity and calibration factors have been calculated and measured in radiation fields of 252Cf fission neutrons, WWR-S reactor neutrons with and without Cd and Fe shielding, 3-MeV (d,t) generator neutrons, and 238PuBe neutrons. Measurement range and achievable accuracy are discussed from the point of view of applying the dosemeter in routine and emergency uses

  11. A Steady State Neutronics Solutions to the OECD/NEA PBMR-400 Coupled Benchmark Problem by using the MARS-GCR/CAPP Code

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Chul; Lee, Seung Wook; Noh, Jae Man; Jeong, Jae Jun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2007-07-01

    The OECD/NEA PBMR-400 neutronics/thermal hydraulics benchmark problem was recently proposed to test the existing analysis methods for high temperature gas-cooled reactors (HTGRs) and to develop more accurate and efficient tools to analyze the neutronics and thermal-hydraulic behavior for the design and safety evaluations of the PBMR. There are three cases in the steady state phase (Phase I). They are the neutronics stand-alone case with fixed cross sections (Exercise 1), the thermal-hydraulics stand-alone case with given heat source (Exercise 2), and the neutronics/thermal hydraulics couple case (Exercise 3), which is the initial condition for the cases in the transient state phase (Phase II). In our previous work, we tried to use the hex-z solver of the MASTER code for the neutronics solutions of exercise 1. However, we observed a large azimuthal dependency of the neutronics solution which was additionally introduced by the zigzag core/reflector boundary in the hex-z model. In this paper, we present the neutronics solutions of the newly developed CAPP (Core Analyzer for Pebble and Prismatic type VHTRs) code to exercise 3 as well as exercise 1.

  12. Automated full-field range OPD and MTF measurement bench for automotive objective benchmark

    Science.gov (United States)

    Boucher, W.; Yonnet, M.; Brahmi, D.; Gascon, A.; Deprez, M.; Wattellier, B.; Lavergne, O.

    2015-10-01

    We present a metrology bench used to benchmark the optical quality of lenses used in automotive applications. These lenses have a wide field of view, typically larger than 180° and fast numerical apertures (F/2). Lenses are compared in terms of OPD and MTF. For this aim, interferometric solutions would require double-passing the lens. Between two field positions, it would be necessary to realign the reference sphere. This is not compatible with the requested high measurement throughput. Therefore wave front sensing is the best solution to this problem because it is able to characterize lenses in single pass configurations. We chose to measure the transmitted wave front with a QuadriWave Lateral Shearing Inferferometer wave front sensor placed directly after the focal plane. This technology is best suited in this case because it has the unique ability to measure fast diverging beams with high accuracy. It can also accept the large tilt angles due to the lens non telecentricity. Because the information needed for lens comparison is the OPD in the exit pupil, the wave front is then back-propagated to it thanks to an innovative ray-trace algorithm. This algorithm is also able to deduce the aperture transmission to take into account vignetting effects that appear at the field edges. Finally the MTF is simulated from the OPD and the pupil function. This bench is fully automated to rapidly benchmark a large number of lenses in their complete field of view. We characterized the bench according to the ISO 5725 standard. Its precision was tested with commercial lenses whereas trueness was assessed with calibrated lenses. The accuracy on MTF was found to be below 1% over the whole field of view.

  13. An active pixels spectrometers for neutronic fields metrology

    International Nuclear Information System (INIS)

    The fundamental metrology is responsible for the sustainability of the measurement systems and handles to supply the reference standards. Concerning the metrology of ionizing radiations and, in particular the neutron metrology, detectors standards are used to characterize reference fields, in terms of energy and fluence. The dosimeters or particle detectors are calibrated on these reference fields. This thesis presents the development of a neutron spectrometer neutron candidate to the status of primary standard for the characterization of neutron fields in the range from 5 to 20 MeV. The spectrometer uses the recoil proton telescope as detection principle; the CMOS technology, through three sensor positions, is taking advantage to realize the tracking of protons. A Si(Li) detector handles the measure of the residual proton energy. The device simulations, realized under MCNPX, allow to estimate its performances and to validate the neutron energy reconstruction. An essential step of characterization of the telescope elements and in particular of CMOS sensors is also proposed to guarantee the validity of posterior experimental measurements. The tests realized as well in mono-energy fields as in radionuclide source show the very good performances of the system. The quantification of uncertainties indicates an energy estimation with 1.5 % accuracy and a resolution of less than 6 %. The fluence measurement is performed with an uncertainty about 4 to 6%. (author)

  14. Cooling of Neutron Stars with Strong Toroidal Magnetic Fields

    CERN Document Server

    Page, D; Küker, M; Page, Dany; Geppert, Ulrich; Kueker, Manfred

    2007-01-01

    We present models of temperature distribution in the crust of a neutron star in the presence of a strong toroidal component superposed to the poloidal component of the magnetic field. The presence of such a toroidal field hinders heat flow toward the surface in a large part of the crust. As a result, the neutron star surface presents two warm regions surrounded by extended cold regions and has a thermal luminosity much lower than in the case the magnetic field is purely poloidal. We apply these models to calculate the thermal evolution of such neutron stars and show that the lowered photon luminosity naturally extends their life-time as detectable thermal X-ray sources.

  15. Neutron matter under strong magnetic fields: a comparison of models

    CERN Document Server

    Aguirre, R; Vidaña, I

    2013-01-01

    The equation of state of neutron matter is affected by the presence of a magnetic field due to the intrinsic magnetic moment of the neutron. Here we study the equilibrium configuration of this system for a wide range of densities, temperatures and magnetic fields. Special attention is paid to the behavior of the isothermal compressibility and the magnetic susceptibility. Our calculation is performed using both microscopic and phenomenological approaches of the neutron matter equation of state, namely the Brueckner--Hartree--Fock (BHF) approach using the Argonne V18 nucleon-nucleon potential supplemented with the Urbana IX three-nucleon force, the effective Skyrme model in a Hartree--Fock description, and the Quantum Hadrodynamic formulation with a mean field approximation. All these approaches predict a change from completely spin polarized to partially polarized matter that leads to a continuous equation of state. The compressibility and the magnetic susceptibility show characteristic behaviors, which reflec...

  16. A compact neutron scatter camera for field deployment.

    Science.gov (United States)

    Goldsmith, John E M; Gerling, Mark D; Brennan, James S

    2016-08-01

    We describe a very compact (0.9 m high, 0.4 m diameter, 40 kg) battery operable neutron scatter camera designed for field deployment. Unlike most other systems, the configuration of the sixteen liquid-scintillator detection cells are arranged to provide omnidirectional (4π) imaging with sensitivity comparable to a conventional two-plane system. Although designed primarily to operate as a neutron scatter camera for localizing energetic neutron sources, it also functions as a Compton camera for localizing gamma sources. In addition to describing the radionuclide source localization capabilities of this system, we demonstrate how it provides neutron spectra that can distinguish plutonium metal from plutonium oxide sources, in addition to the easier task of distinguishing AmBe from fission sources. PMID:27587113

  17. A compact neutron scatter camera for field deployment

    CERN Document Server

    Goldsmith, John E M; Brennan, James S

    2016-01-01

    We describe a very compact (0.9 m high, 0.4 m diameter, 40 kg) battery operable neutron scatter camera designed for field deployment. Unlike most other systems, the configuration of the sixteen liquid-scintillator detection cells are arranged to provide omnidirectional (4{\\pi}) imaging with sensitivity comparable to a conventional two-plane system. Although designed primarily to operate as a neutron scatter camera for localizing energetic neutron sources, it also functions as a Compton camera for localizing gamma sources. In addition to describing the radionuclide source localization capabilities of this system, we demonstrate how it provides neutron spectra that can distinguish plutonium metal from plutonium oxide sources, in addition to the easier task of distinguishing AmBe from fission sources.

  18. A stochastic transport theory of neutron and photon coupled fields neutron and photon counting statistics in nuclear assemblies

    International Nuclear Information System (INIS)

    The behavior of neutrons and gamma rays in a nuclear reactor or configuration of fissile material can be represented as a stochastic process. The observation of this stochastic process is usually achieved by measuring the fluctuations of the neutron and gamma ray population on the system. The general theory of the stochastic neutron field has been developed to a high degree. However, the theory of the stochastic nature of the gamma rays and neutrons couples the two processes. The generalized probability balances are developed from which the first and higher moments of the neutron and gamma rays fields are obtained. The paper also provides a description of the probability generating functions for both photon and neutron detectors that are the foundations for measurements of the fluctuations. The formalism developed in this paper for the representation of the statistical descriptors of the neutron-photon coupled field is applicable for many neutron noise analysis measurements

  19. Benchmark Modeling of the Near-Field and Far-Field Wave Effects of Wave Energy Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Rhinefrank, Kenneth E; Haller, Merrick C; Ozkan-Haller, H Tuba

    2013-01-26

    This project is an industry-led partnership between Columbia Power Technologies and Oregon State University that will perform benchmark laboratory experiments and numerical modeling of the near-field and far-field impacts of wave scattering from an array of wave energy devices. These benchmark experimental observations will help to fill a gaping hole in our present knowledge of the near-field effects of multiple, floating wave energy converters and are a critical requirement for estimating the potential far-field environmental effects of wave energy arrays. The experiments will be performed at the Hinsdale Wave Research Laboratory (Oregon State University) and will utilize an array of newly developed Buoys' that are realistic, lab-scale floating power converters. The array of Buoys will be subjected to realistic, directional wave forcing (1:33 scale) that will approximate the expected conditions (waves and water depths) to be found off the Central Oregon Coast. Experimental observations will include comprehensive in-situ wave and current measurements as well as a suite of novel optical measurements. These new optical capabilities will include imaging of the 3D wave scattering using a binocular stereo camera system, as well as 3D device motion tracking using a newly acquired LED system. These observing systems will capture the 3D motion history of individual Buoys as well as resolve the 3D scattered wave field; thus resolving the constructive and destructive wave interference patterns produced by the array at high resolution. These data combined with the device motion tracking will provide necessary information for array design in order to balance array performance with the mitigation of far-field impacts. As a benchmark data set, these data will be an important resource for testing of models for wave/buoy interactions, buoy performance, and far-field effects on wave and current patterns due to the presence of arrays. Under the proposed project we will initiate

  20. Benchmark Modeling of the Near-Field and Far-Field Wave Effects of Wave Energy Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Rhinefrank, Kenneth E.; Haller, Merrick C.; Ozkan-Haller, H. Tuba

    2013-01-26

    This project is an industry-led partnership between Columbia Power Technologies and Oregon State University that will perform benchmark laboratory experiments and numerical modeling of the near-field and far-field impacts of wave scattering from an array of wave energy devices. These benchmark experimental observations will help to fill a gaping hole in our present knowledge of the near-field effects of multiple, floating wave energy converters and are a critical requirement for estimating the potential far-field environmental effects of wave energy arrays. The experiments will be performed at the Hinsdale Wave Research Laboratory (Oregon State University) and will utilize an array of newly developed Buoys that are realistic, lab-scale floating power converters. The array of Buoys will be subjected to realistic, directional wave forcing (1:33 scale) that will approximate the expected conditions (waves and water depths) to be found off the Central Oregon Coast. Experimental observations will include comprehensive in-situ wave and current measurements as well as a suite of novel optical measurements. These new optical capabilities will include imaging of the 3D wave scattering using a binocular stereo camera system, as well as 3D device motion tracking using a newly acquired LED system. These observing systems will capture the 3D motion history of individual Buoys as well as resolve the 3D scattered wave field; thus resolving the constructive and destructive wave interference patterns produced by the array at high resolution. These data combined with the device motion tracking will provide necessary information for array design in order to balance array performance with the mitigation of far-field impacts. As a benchmark data set, these data will be an important resource for testing of models for wave/buoy interactions, buoy performance, and far-field effects on wave and current patterns due to the presence of arrays. Under the

  1. The Covariance and Bicovariance of the Stochastic Neutron Field

    International Nuclear Information System (INIS)

    On the basis of the general stochastic neutron field theory developed by Munoz-Cobo et al, results on the covariance and bicovariance of the neutron field have been presented. These two statistical quantities are obtained from the counts observed in detectors operating during a period of time (gate length), Δqc. A classical example is the so called Feynmann Y-function that is defined as the variance to mean ratio of the neutron field. Upon taking the limit of the covariance and bicovariance function for Δqc rarrow O , one obtains the two and three detector cross correlation functions respectively. The mathematical structure of the results so obtained have a transparent physical interpretation in terms of the space and delay time overlap between the field-of-view of the detectors. For the first time, an expression has been obtained for the bispectrum function of the stochastic neutron field and for the appropriate weight functions to be used as space-energy-angle correction factors for the one-point kinetics approximation

  2. Fast neutron fields imaging with a CCD-based luminescent detector

    International Nuclear Information System (INIS)

    The paper considers some questions concerned with the development of an imaging system based on a CCD-detector for visualising fast neutron fields. From those the most important are: development of fast neutron screens, detector resistance to irradiation fields, and feasibility of fast neutron radiography and tomography at various neutron sources

  3. Fast neutron fields imaging with a CCD-based luminescent detector

    CERN Document Server

    Mikerov, V

    1999-01-01

    The paper considers some questions concerned with the development of an imaging system based on a CCD-detector for visualising fast neutron fields. From those the most important are: development of fast neutron screens, detector resistance to irradiation fields, and feasibility of fast neutron radiography and tomography at various neutron sources.

  4. Evolutions of Neutron Stars and their Magnetic Fields

    CERN Document Server

    Bisnovatyi-Kogan, G S

    2016-01-01

    Estimations of magnetic fields of neutron stars, observed as radio and X-ray pulsars, are discussed. It is shown, that theoretical and observational values for different types of radiopulsars are in good correspondence. Radiopulsars in close binaries and millisecond pulsars, which have passed the stage of disk accretion (recycled radiopulsars), have magnetic fields 2-4 orders of magnitude smaller than ordinary single pulsars. Most probably, the magnetic field of the neutron star was screened by the infalling material. Several screening models are considered. Formation of single recycled pulsars loosing its companion is discussed. Magnetic fields of some X-ray pulsars are estimated from the cyclotron line energy. In the case of Her X-1 this estimation exceeds considerably the value of its magnetic field obtained from long term observational data related to the beam structure evolution. Another interpretation of the cyclotron feature, based on the relativistic dipole radiation mechanism, could remove this discr...

  5. A compact neutron generator using a field ionization source

    Energy Technology Data Exchange (ETDEWEB)

    Persaud, Arun [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Waldmann, Ole [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kapadia, Rehan [Univ. of California, Berkeley, CA (United States); Takei, Kuniharu [Univ. of California, Berkeley, CA (United States); Javey, Ali [Univ. of California, Berkeley, CA (United States); Schenkel, Thomas [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-02-15

    We study field ionization as a means to create ions for compact and rugged neutron source. Arrays of carbon nano-fibers promise the high field-enhancement factors required for efficient field ionization. We report on the fabrication of arrays of field emitters with a density up to 106 tips/cm2 and measure their performance characteristics using electron field emission. Lastly, the critical issue of uniformity is discussed, as are efforts towards coating the nano-fibers to enhance their lifetime and surface properties.

  6. A compact neutron generator using a field ionization source

    Energy Technology Data Exchange (ETDEWEB)

    Persaud, Arun; Waldmann, Ole; Schenkel, Thomas [E.O. Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kapadia, Rehan; Takei, Kuniharu; Javey, Ali [Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720 (United States)

    2012-02-15

    Field ionization as a means to create ions for compact and rugged neutron sources is pursued. Arrays of carbon nano-fibers promise the high field-enhancement factors required for efficient field ionization. We report on the fabrication of arrays of field emitters with a density up to 10{sup 6} tips/cm{sup 2} and measure their performance characteristics using electron field emission. The critical issue of uniformity is discussed, as are efforts towards coating the nano-fibers to enhance their lifetime and surface properties.

  7. Neutronics Benchmarks for the Utilization of Mixed-Oxide Fuel: Joint U.S./Russian Progress Report for Fiscal Year 1997 Volume 2-Calculations Performed in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Primm III, RT

    2002-05-29

    This volume of the progress report provides documentation of reactor physics and criticality safety studies conducted in the US during fiscal year 1997 and sponsored by the Fissile Materials Disposition Program of the US Department of Energy. Descriptions of computational and experimental benchmarks for the verification and validation of computer programs for neutron physics analyses are included. All benchmarks include either plutonium, uranium, or mixed uranium and plutonium fuels. Calculated physics parameters are reported for all of the computational benchmarks and for those experimental benchmarks that the US and Russia mutually agreed in November 1996 were applicable to mixed-oxide fuel cycles for light-water reactors.

  8. Semiclassical description of neutron polarization in an inhomogeneous magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Naida, O.N.; Prudkovskii, A.G.

    1978-12-01

    A method is obtained for constructing the semiclassical solutions to the Pauli equation for the neutron in a magnetic field which describe both the Stern-Gerlach beam splitting and spin-flip processes. The accuracy of these solutions makes it possible (in contrast to the known semiclassical methods) to describe interference phenomena, which can be interpreted as corrections to the Larmor precession.

  9. Spot--like Structures of Neutron Star Surface Magnetic Fields

    CERN Document Server

    Geppert, U; Gil, J

    2003-01-01

    There is growing evidence, based on both X-ray and radio observations of isolated neutron stars, that besides the large--scale (dipolar) magnetic field, which determines the pulsar spin--down behaviour, small--scale poloidal field components are present, which have surface strengths one to two orders of magnitude larger than the dipolar component. We argue in this paper that the Hall--effect can be an efficient process in producing such small--scale field structures just above the neutron star surface. It is shown that due to a Hall--drift induced instability, poloidal magnetic field structures can be generated from strong subsurface toroidal fields, which are the result of either a dynamo or a thermoelectric instability acting at early times of a neutron star's life. The geometrical structure of these small--scale surface anomalies of the magnetic field resembles that of some types of ``star--spots''. The magnetic field strength and the length--scales are comparable with values that can be derived from vario...

  10. A comparison of neutron beams for BNCT based on in-phantom neutron field assessment parameters

    International Nuclear Information System (INIS)

    In this paper our in-phantom neutron field assessment parameters, T and DTumor, were used to evaluate several neutron sources for use in BNCT. Specifically, neutron fields from The Ohio State University (OSU) Accelerator-Based Neutron Source (ABNS) design, two alternative ABNS designs from the literature (the Al/AlF3-Al2O3 ABNS and the 7LiF-Al2O3 ABNS), a fission-convertor plate concept based on the 500-kW OSU Research Reactor (OSURR), and the Brookhaven Medical Research Reactor (BMRR) facility were evaluated. In order to facilitate a comparison of the various neutron fields, values of T and DTumor were calculated in a 14 cmx14 cmx14 cm lucite cube phantom located in the treatment port of each neutron source. All of the other relevant factors, such as phantom materials, kerma factors, and treatment parameters, were kept the same. The treatment times for the OSURR, the 7LiF-Al2O3 ABNS operating at a beam current of 10 mA, and the BMRR were calculated to be comparable and acceptable, with a treatment time per fraction of approximately 25 min for a four fraction treatment scheme. The treatment time per fraction for the OSU ABNS and the Al/AlF3-Al2O3 ABNS can be reduced to below 30 min per fraction for four fractions, if the proton beam current is made greater than approximately 20 mA. DTumor was calculated along the beam centerline for tumor depths in the phantom ranging from 0 to 14 cm. For tumor depths ranging from 0 to approximately 1.5 cm, the value of DTumor for the OSURR is largest, while for tumor depths ranging from 1.5 to approximately 14 cm, the value of DTumor for the OSU-ABNS is the largest

  11. PENTrack---a simulation tool for ultracold neutrons, protons, and electrons in complex electromagnetic fields and geometries

    CERN Document Server

    Schreyer, Wolfgang; Losekamm, Martin J; Paul, Stephan; Picker, Rüdiger

    2016-01-01

    Modern precision experiments trapping low-energy particles require detailed simulations of particle trajectories and spin precession to determine systematic measurement limitations and apparatus deficiencies. We developed PENTrack, a tool that allows to simulate trajectories of ultracold neutrons and their decay products---protons and electrons---and the precession of their spins in complex geometries and electromagnetic fields. The interaction of ultracold neutrons with matter is implemented with the Fermi-potential formalism and micro-roughness scattering. The results of several benchmark simulations agree with STARucn v1.2, uncovered several flaws in \\textsc{Geant4} v10.2.2, and agree with experimental data. Experiment geometry and electromagnetic fields can be imported from commercial computer-aided-design and finite-element software. All simulation parameters are defined in simple text files allowing quick changes. The simulation code is written in C++ and is freely available at github.com/wschreyer/PENT...

  12. Torsional oscillations of neutron stars with highly tangled magnetic fields

    CERN Document Server

    Sotani, Hajime

    2015-01-01

    To determine the frequencies of magnetic oscillations in the neutron stars with highly tangled magnetic fields, we derive the perturbation equations. We assume that the field strength of the global magnetic structure is so small that such fields are negligible compared with the tangled fields, which may still be far from a realistic configuration. Then, we systematically examine the spectra of the magnetic oscillations, as varying the magnetic field strength and stellar mass. The frequencies without crust elasticity are completely proportional to the strength of magnetic field, whose proportionality constant depends strongly on the stellar mass. On the other hand, the oscillation spectra with crust elasticity become more complicated, where the frequencies even for weak magnetic fields are different from the crustal torsional oscillations without magnetic fields. For discussing the spectra, the critical field strength can play an important role, which is determined in such a way that the shear velocity is equi...

  13. Inner crusts of neutron stars in strongly quantising magnetic fields

    CERN Document Server

    Nandi, Rana; Mishustin, Igor N; Greiner, Walter

    2010-01-01

    We study the properties and stability of nuclei in the inner crust of neutron stars in the presence of strong magnetic fields $\\sim 10^{17}$ G. Nuclei coexist with a neutron gas and reside in a uniform gas of electrons in the inner crust. This problem is investigated within the Thomas-Fermi model. We extract the properties of nuclei based on the subtraction procedure of Bonche, Levit and Vautherin. The phase space modification of electrons due to Landau quantisation in the presence of strong magnetic fields leads to the enhancement of electron as well as proton fractions at lower densities $\\sim 0.001$ fm$^{-3}$. We find the equilibrium nucleus at each average baryon density by minimising the free energy and show that, in the presence of strong magnetic fields, it is lower than that in the field free case. The size of the spherical cell that encloses a nucleus along with the neutron and electron gases becomes smaller in strong magnetic fields compared with the zero field case. Nuclei with larger mass and atom...

  14. Thermal neutron irradiation field design for boron neutron capture therapy of human explanted liver.

    Science.gov (United States)

    Bortolussi, S; Altieri, S

    2007-12-01

    The selective uptake of boron by tumors compared to that by healthy tissue makes boron neutron capture therapy (BNCT) an extremely advantageous technique for the treatment of tumors that affect a whole vital organ. An example is represented by colon adenocarcinoma metastases invading the liver, often resulting in a fatal outcome, even if surgical resection of the primary tumor is successful. BNCT can be performed by irradiating the explanted organ in a suitable neutron field. In the thermal column of the Triga Mark II reactor at Pavia University, a facility was created for this purpose and used for the irradiation of explanted human livers. The neutron field distribution inside the organ was studied both experimentally and by means of the Monte Carlo N-particle transport code (MCNP). The liver was modeled as a spherical segment in MCNP and a hepatic-equivalent solution was used as an experimental phantom. In the as-built facility, the ratio between maximum and minimum flux values inside the phantom ((phi(max)/phi(min)) was 3.8; this value can be lowered to 2.3 by rotating the liver during the irradiation. In this study, the authors proposed a new facility configuration to achieve a uniform thermal neutron flux distribution in the liver. They showed that a phi(max)/phi(min) ratio of 1.4 could be obtained without the need for organ rotation. Flux distributions and dose volume histograms were reported for different graphite configurations. PMID:18196797

  15. Benchmark problem proposal

    International Nuclear Information System (INIS)

    The meeting of the Radiation Energy Spectra Unfolding Workshop organized by the Radiation Shielding Information Center is discussed. The plans of the unfolding code benchmarking effort to establish methods of standardization for both the few channel neutron and many channel gamma-ray and neutron spectroscopy problems are presented

  16. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    CERN Document Server

    Caresana, M; Esposito, A; Ferrarini, M; Golnik, N; Hohmann, E; Leuschner, A; Luszik-Bhadra, M; Manessi, G; Mayer, S; Ott, K; Röhrich, J; Silari, M; Trompier, F; Volnhals, M; Wielunski, M

    2014-01-01

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instru...

  17. The PTB thermal neutron reference field at GeNF

    Energy Technology Data Exchange (ETDEWEB)

    Boettger, R.; Friedrich, H.; Janssen, H.

    2004-07-01

    The experimental setup and procedure for the characterization of the thermal neutron reference field established at the Geesthacht neutron facility (GeNF) of the GKSS is described. The neutron beam, free in air, with a maximum flux of 10{sup 6} s{sup -1}, can easily be reduced to less than 10{sup 4} s{sup -1} by using a diaphragm variable in size and without changing the beam divergence. Also, the spectral distribution with a mean energy of 45 meV, measured by time-of-flight over a 6.6 m long flight path, is independent of the beam current chosen. In the 2002/2003 experiments reported here, a {sup 6}Li glass detector was employed to determine the absolute beam current and to calibrate the {sup 3}He transmission beam monitor. In addition, activation measurements of gold foils were carried out at a reduced beam divergence. The results agree within {+-}2%. Furthermore, the beam is characterized by a low gamma background intensity and a negligible fraction of epithermal neutrons. Irradiations in combination with a scanner device to achieve a homogeneously illuminated scan field have shown that the thermal beam is well suited for dosemeter development and for the calibration of radiation protection instruments. (orig.)

  18. Relativistic mean field models for finite nuclei and neutron stars

    Science.gov (United States)

    Chen, Wei-Chia

    In this dissertation we have created theoretical models for finite nuclei, nuclear matter, and neutron stars within the framework of relativistic mean field (RMF) theory, and we have used these models to investigate the elusive isovector sector and related physics, in particular, the neutron-skin thickness of heavy nuclei, the nuclear symmetry energy, and the properties of neutron stars. To build RMF models that incorporate collective excitations in finite nuclei in addition to their ground-state properties, we have extended the non-relativistic sum rule approach to the relativistic domain. This allows an efficient estimate of giant monopole energies. Moreover, we have combined an exact shell-model-like approach with the mean-field calculation to describe pairing correlations in open-shell nuclei. All the ingredients were then put together to establish the calibration scheme. We have also extended the transformation between model parameters and pseudo data of nuclear matter within the RMF context. Performing calibration in this pseudo data space can not only facilitate the searching algorithm but also make the pseudo data genuine model predictions. This calibration scheme is also supplemented by a covariance analysis enabling us to extract the information content of a model, including theoretical uncertainties and correlation coefficients. A series of RMF models subject to the same isoscalar constraints but one differing isovector assumption were then created using this calibration scheme. By comparing their predictions of the nuclear matter equation of state to both experimental and theoretical constraints, we found that a small neutron skin of about 0.16 fm in Pb208 is favored, indicating that the symmetry energy should be soft. To obtain stronger evidence, we proceeded to examine the evolution of the isotopic chains in both oxygen and calcium. Again, it was found that the model with such small neutron skin and soft symmetry energy can best describe both isotopic

  19. Characterization of neutron reference fields at US Department of Energy calibration fields.

    Science.gov (United States)

    Olsher, R H; McLean, T D; Mallett, M W; Seagraves, D T; Gadd, M S; Markham, Robin L; Murphy, R O; Devine, R T

    2007-01-01

    The Health Physics Measurements Group at the Los Alamos National Laboratory (LANL) has initiated a study of neutron reference fields at selected US Department of Energy (DOE) calibration facilities. To date, field characterisation has been completed at five facilities. These fields are traceable to the National Institute for Standards and Technology (NIST) through either a primary calibration of the source emission rate or through the use of a secondary standard. However, neutron spectral variation is caused by factors such as room return, scatter from positioning tables and fixtures, source anisotropy and spectral degradation due to source rabbits and guide tubes. Perturbations from the ideal isotropic point source field may impact the accuracy of instrument calibrations. In particular, the thermal neutron component of the spectrum, while contributing only a small fraction of the conventionally true dose, can contribute a significant fraction of a dosemeter's response with the result that the calibration becomes facility-specific. A protocol has been developed to characterise neutron fields that relies primarily on spectral measurements with the Bubble Technology Industries (BTI) rotating neutron spectrometer (ROSPEC) and the LANL Bonner sphere spectrometer. The ROSPEC measurements were supplemented at several sites by the BTI Simple Scintillation Spectrometer probe, which is designed to extend the ROSPEC upper energy range from 5 to 15 MeV. In addition, measurements were performed with several rem meters and neutron dosemeters. Detailed simulations were performed using the LANL MCNPX Monte Carlo code to calculate the magnitude of source anisotropy and scatter factors.

  20. An investigation of neutron and gamma fields originating from the operation of a nuclear reactor

    International Nuclear Information System (INIS)

    The testing and usage of a suite of computer programs applicable to 1-D shielding analyses is described. The motion of radiation through matter and its interaction with the medium through which it propagates is described by the Boltzmann transport equation. This complex equation usually cannot be solved analytically. It can however be re-written in the so-called Discrete Ordinates form which is successfully solved by digital computer. Computer software is an invaluable tool in finding cost effective solutions to the problem of ensuring that people and materials are safely shielded from the harmful effects of radiation. The package of computer program SCALE-3 contains several modules which can be used to devise solutions to 1-D shielding problems. However, before they can be applied, the user's ability to obtain and interpret meaningful results must be validated. This is achieved by means of comparative studies called benchmarks. Two benchmark studies were performed. The first assesses the ability to apply the software in question to solve a problem associated with the safe transportation of spent nuclear fuel. This was achieved by repeating the shielding analysis of a simplified cast iron cask found in the literature and comparing results. For the second benchmark, the properties of neutron and gamma-ray fields found around an operating nuclear reactor were evaluated and compared to those obtained using alternative technology. Using the computer technology thus tested, a complete shielding analysis of a cask being considered for the transportation of spent nuclear fuel was performed. 27 figs., 9 tabs., 34 refs

  1. Establishing local workplace field correction factors for neutron personal dosemeters

    International Nuclear Information System (INIS)

    The present personal neutron dosemeters still need local correction factors to be able to provide accuracy comparable with photon dosemeters. Characterisation of the local neutron field is an indispensable part of neutron dosimetry to obtain such correction factors. It is often overlooked that besides characterisation in the neutron energy also the directional distribution of neutrons plays a crucial part in this characterisation. The authors have done such characterisation in the energy and angle for four workplace fields in Paks NPP. For this a relatively simple approximation method was used using the Nprobe for the energy distribution and measurements on the six sides of the slab phantom with personal dosemeters for the directional distribution. This allowed one to estimate a reference neutron Hp(10) rate and to compare it with the response of several neutron personal dosemeters. In October 2011, a measurement campaign was set-up in Paks NPP, which is a VVER reactor type. The measurements were performed to estimate reference values for personal dose equivalent rates dHp(10)/dt and to evaluate the behaviour of several personal dosemeters at different locations inside the plant. Two locations in the pump room and two locations in the reactor hall were chosen. Instead of just assuming that the fluence is unidirectional or that the fluence is isotropic, an attempt was made to estimate the directional distribution of the neutron field using a relatively simple measurement procedure. A number of active and passive personal dosemeters were placed on the six faces of a slab phantom and the results were analysed to obtain partial fluences in several directions of incidence. This method has important limitations, but is relatively simple to perform. The results show that it is very important to include the directional distribution in the Hp(10) evaluation. When comparing Hp(10)/dt and H*(10)/dt, H*(10) can be considered a conservative value for Hp(10). In the pump room H

  2. The freedom to choose neutron star magnetic field equilibria

    CERN Document Server

    Glampedakis, Kostas

    2016-01-01

    Our ability to interpret and glean useful information from the large body of observations of strongly magnetised neutron stars rests largely on our theoretical understanding of magnetic field equilibria. We answer the following question: is one free to arbitrarily prescribe magnetic equilibria such that fluid degrees of freedom can balance the equilibrium equations? We examine this question for various models for neutron star matter; from the simplest single-fluid barotrope to more realistic non-barotropic multifluid models with superfluid/superconducting components, muons and entropy. We do this for both axi- and non-axisymmetric equilibria, and in Newtonian gravity and general relativity. We show that, in axisymmetry, the most realistic model allows complete freedom in choosing a magnetic field equilibrium whereas non-axisymmetric equilibria are never completely arbitrary.

  3. The freedom to choose neutron star magnetic field equilibria

    Science.gov (United States)

    Glampedakis, Kostas; Lasky, Paul D.

    2016-08-01

    Our ability to interpret and glean useful information from the large body of observations of strongly magnetised neutron stars rests largely on our theoretical understanding of magnetic field equilibria. We answer the following question: is one free to arbitrarily prescribe magnetic equilibria such that fluid degrees of freedom can balance the equilibrium equations? We examine this question for various models for neutron star matter; from the simplest single-fluid barotrope to more realistic non-barotropic multifluid models with superfluid/superconducting components, muons and entropy. We do this for both axi- and non-axisymmetric equilibria, and in Newtonian gravity and general relativity. We show that, in axisymmetry, the most realistic model allows complete freedom in choosing a magnetic field equilibrium whereas non-axisymmetric equilibria are never completely arbitrary.

  4. Radiative Neutron Capture on Carbon-14 in Effective Field Theory

    OpenAIRE

    Rupak, Gautam; Fernando, Lakma; Vaghani, Akshay

    2012-01-01

    The cross section for radiative capture of neutron on carbon-14 is calculated using the model-independent formalism of halo effective field theory. The dominant contribution from E1 transition is considered, and the cross section is expressed in terms of elastic scattering parameters of the effective range expansion. Contributions from both resonant and non-resonant interaction are calculated. Significant interference between these leads to a capture contribution that deviates from simple Bre...

  5. Neutron star mass-radius relation with gravitational field shielding by a scalar field

    Institute of Scientific and Technical Information of China (English)

    Bo-Jun Zhang; Tian-Xi Zhang; Padmaja Guggilla; Mostafa Dokhanian

    2013-01-01

    The currently well-developed models for equations of state (EoSs) have been severely impacted by recent measurements of neutron stars with a small radius and/or large mass.To explain these measurements,the theory of gravitational field shielding by a scalar field is applied.This theory was recently developed in accordance with the five-dimensional (5D) fully covariant Kaluza-Klein (KK) theory that has successfully unified Einstein's general relativity and Maxwell's electromagnetic theory.It is shown that a massive,compact neutron star can generate a strong scalar field,which can significantly shield or reduce its gravitational field,thus making it more massive and more compact.The mass-radius relation developed under this type of modified gravity can be consistent with these recent measurements of neutron stars.In addition,the effect of gravitational field shielding helps explain why the supernova explosions of some very massive stars (e.g.,40 M⊙ as measured recently) actually formed neutron stars rather than black holes as expected.The EoS models,ruled out by measurements of small radius and/or large mass neutron stars according to the theory of general relativity,can still work well in terms of the 5D fully covariant KK theory with a scalar field.

  6. Intercomparison of radiation protection devices in a high-energy stray neutron field, Part II: Bonner sphere spectrometry

    International Nuclear Information System (INIS)

    The European Commission has funded within its 6th Framework Programme a three-year project (2005-2007) called CONRAD, COordinated Network for RAdiation Dosimetry. A major task of the CONRAD Work Package 'complex mixed radiation fields at workplaces' was to organise a benchmark exercise in a workplace field at a high-energy particle accelerator where neutrons are the dominant radiation component. The CONRAD benchmark exercise took place at the Gesellschaft fuer Schwerionenforschung mbH (GSI) in Darmstadt, Germany in July 2006. In this paper, the results of the spectrometry using four extended -range Bonner sphere spectrometers of four different institutes are reported. Outside Cave A the neutron spectra were measured with three spectrometers at six selected positions and ambient dose equivalent values were derived for use in the intercomparison with other area monitors and dosemeters. At a common position all three spectrometers were used to allow a direct comparison of their results which acts as an internal quality assurance. The comparison of the neutron spectra measured by the different groups shows very good agreement. A detailed analysis presents some differences between the shapes of the spectra and possible sources of these differences are discussed. However, the ability of Bonner sphere spectrometers to provide reliable integral quantities like fluence and ambient dose equivalent is well demonstrated in this exercise. The fluence and dose results derived by the three groups agree very well within the given uncertainties, not only with respect to the total energy region present in this environment but also for selected energy regions which contribute in certain strength to the total values. In addition to the positions outside Cave A one spectrometer was used to measure the neutron spectrum at one position in the entry maze of Cave A. In this case a comparison was possible to earlier measurements.

  7. Intercomparison of radiation protection devices in a high-energy stray neutron field. Part II: Bonner sphere spectrometry

    CERN Document Server

    Wiegel, B; Bedogni, R; Caresana, M; Esposito, A; Fehrenbacher, G; Ferrarini, M; Hohmann, E; Hranitzky, C; Kasper, A; Khurana, S; Mares, V; Reginatto, M; Rollet, S; Rühm, W; Schardt, D; Silari, M; Simmer, G; Weitzenegger, E

    2009-01-01

    The European Commission has funded within its 6th Framework Programme a three-year project (2005–2007) called CONRAD, COordinated Network for RAdiation Dosimetry. A major task of the CONRAD Work Package “complex mixed radiation fields at workplaces” was to organise a benchmark exercise in a workplace field at a high-energy particle accelerator where neutrons are the dominant radiation component. The CONRAD benchmark exercise took place at the Gesellschaft für Schwerionenforschung mbH (GSI) in Darmstadt, Germany in July 2006. In this paper, the results of the spectrometry using four extended -range Bonner sphere spectrometers of four different institutes are reported. Outside Cave A the neutron spectra were measured with three spectrometers at six selected positions and ambient dose equivalent values were derived for use in the intercomparison with other area monitors and dosemeters. At a common position all three spectrometers were used to allow a direct comparison of their results which acts as an int...

  8. Neutron spectrometry in mixed fields: superheated drop (bubble) detectors.

    Science.gov (United States)

    d'Errico, F; Matzke, M

    2003-01-01

    The BINS neutron threshold spectrometer permits the analysis of the main features of a neutron field for radiation protection purposes. The system offers a virtually complete photon discrimination and nested threshold responses to neutrons, which allow the use of very effective 'few-channel' unfolding procedures. To date, the practical operating energy range of a BINS is 0.1-10 MeV, over which a resolving power of 20-30% can be expected when the deconvolution is performed without explicit pre-information. Spectrum unfolding results in relatively high uncertainties on the differential fluence distributions, but due to negative correlations in adjacent energy groups the uncertainties on integral quantities such as dose equivalent are small and of the order of 5% to 10%, similar to the results of other active spectrometers. In comparison with most radiation detectors, the BINS is an extremely slow system due to the intrinsic duration of a bubble pulse and to the time associated with pulse analysis. For example, the maximum sustainable fluence rate of 1 MeV neutrons is about 10(4) cm(-2) s(-1), which is low for many neutron physics experiments. However, this rate corresponds to an ambient dose equivalent rate of about 1 mSv h(-1), making the active device adequate for radiation protection applications in the workplaces described in Section 1. There are ample margins for improvement of the spectrometer. In particular, in the low-energy region a thermal-epithermal neutron group may be added by using chlorine-bearing emulsions stabilised at suitable temperatures. In fact, the latest version of the system achieves this goal by using a single superheated emulsion of dichlorotetrafluoroethane (R-114) operated at temperatures up to 55 degrees C. This extends the range of the spectrometer and at the same time removes the undue enhancement of the UNFANA output in the low energy region. Above 10 MeV, the resolution can be improved by adding more thresholds, e.g. by starting from

  9. A militarily fielded thermal neutron activation sensor for landmine detection

    Energy Technology Data Exchange (ETDEWEB)

    Clifford, E.T.H. [Bubble Technology Industries, Chalk River (Canada); McFee, J.E. [Defence R and D Canada-Suffield, Medicine Hat (Canada)], E-mail: john.mcfee@drdc-rddc.gc.ca; Ing, H.; Andrews, H.R.; Tennant, D.; Harper, E. [Bubble Technology Industries, Chalk River (Canada); Faust, A.A. [Defence R and D Canada-Suffield, Medicine Hat (Canada)

    2007-08-21

    The Canadian Department of National Defence has developed a teleoperated, vehicle-mounted, multi-sensor system to detect anti-tank landmines on roads and tracks in peacekeeping operations. A key part of the system is a thermal neutron activation (TNA) sensor which is placed above a suspect location to within a 30 cm radius and confirms the presence of explosives via detection of the 10.835 MeV gamma ray associated with thermal neutron capture on {sup 14}N. The TNA uses a 100{mu}g{sup 252}Cf neutron source surrounded by four 7.62cmx7.62cm NaI(Tl) detectors. The system, consisting of the TNA sensor head, including source, detectors and shielding, the high-rate, fast pulse processing electronics and the data processing methodology are described. Results of experiments to characterize detection performance are also described. The experiments have shown that anti-tank mines buried 10 cm or less can be detected in roughly a minute or less, but deeper mines and mines significantly displaced horizontally take considerably longer time. Mines as deep as 30 cm can be detected for long count times (1000 s). Four TNA detectors are now in service with the Canadian Forces as part of the four multi-sensor systems, making it the first militarily fielded TNA sensor and the first militarily fielded confirmation sensor for landmines. The ability to function well in adverse climatic conditions has been demonstrated, both in trials and operations.

  10. Neutrons field in the neutronic measurements room of the Polytechnic University of Madrid

    International Nuclear Information System (INIS)

    Through of measurements and calculations of a Monte Carlo series has been characterized the neutronic field of the neutronic measurements room of Nuclear Engineering Department of the Polytechnic University of Madrid. The measurements were realized with the Bonner Spheres Spectrometer that allowed establish the spectra on the new stainless steel panel and at different distances measured regarding the source. The values of the speed of environmental equivalent dose were measured with an area monitor Bert hold Lb 6411. Through of Monte Carlo methods was built a detailed model of the room with the panel and the spectra were calculated and, with these the values of the environmental equivalent dose were obtained using the conversion coefficients of the ICRP 74 and the Bert hold Lb 6411 response. The calculated values were compared with those measured and was consistency among the results. (Author)

  11. Neutron Interference in the Gravitational Field of a Ring Laser

    Science.gov (United States)

    Fischetti, Robert

    2013-04-01

    A number of analyses of neutron interference effects due to various metric perturbations have been found in the literature [1,2]. However, the approach of each author depends on a specific metric. I will present a new general technique giving the Foldy-Wouthuysen transformed Hamiltonian for a Dirac particle in the most general linearized space-time metric. I will then apply this new technique to calculate the phase shift on a neutron beam interferometer due to the gravitational field of a ring laser [3].[4pt] [1] D. M Greenberger and A. W. Overhauser, Rev. Mod. Phys. 51, 43--78 (1979).[0pt] [2] F. W. Hehl and W. T. Ni, Phys. Rev. D, vol 42, no. 6, pp. 2045-2048, 1990.[0pt] [3] R. L. Mallett, Phys. Lett. A 269, 214 (2000).

  12. Properties of Neutron Stars Rotating at Kepler Frequency with Uniform Strong Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    WEN De-Hua; CHEN Wei; LU Yi-Gang; LIU Liang-Gang

    2007-01-01

    A uniform strong magnetic field is considered in calculating the properties of neutron star rotating at the Kepler frequency. The results show that the effect of the magnetic field on the properties of neutron star is evident, and the properties of the neutron stars rotating at the Kepler frequency can be used as a criterion to the equations of states of the neutron star matters.

  13. Construction of the Calibration Neutron Fields and Spectrum Weighted Response of Several Detectors

    International Nuclear Information System (INIS)

    The types and the forms of radioactive source term are getting a variety due to expansion of the radiation industry such as medical radiation treatments and research. of materials. For neutron sources, it is necessary to account for the neutron energy distribution to evaluate exactly the dose equivalent, because the energy range of the neutron from thermal neutrons (0.025 eV) to a few GeV. The neutron dose equivalent depends heavily on the energy of the neutrons. The neutron field spectra from a DT neutron generator at Korea Atomic Energy research Institute (KAERI) and the proton accelerators at Korea Institute of Radiological and Medical Science (KIRAMS) were measured by using the Bonner sphere measurement system (BS system) and several neutron detectors. The spectrum weighted response was obtained by using the response function of the neutron detectors as given in the IAEA Technical Report Series 403 (TRS)

  14. Energy response characteristics of several neutron measuring devices determined by using the scattered neutron calibration fields of KAERI

    International Nuclear Information System (INIS)

    The energy response characteristics of several neutron measuring devices used popularly for radiation protection purpose were determined under the simulated neutron calibration fields which was produced by using the radionuclide neutron sources and the shadow objects to scatter and to moderate the fast neutrons emitted from the source. The simulated neutron calibration fields for the calibration of personal dosemeters and survey meters were constructed in the Radiation Calibration Laboratory (RCL) of Korea Atomic Energy Research Institute (KAERI). The radionuclide sources of 252Cf and 241AmBe were used for producing the neutron calibration fields with little different from the method recommended by ISO. The calibration points of interest were behind the shadow objects and the concrete wall in the irradiation room. In order to characterize the neutron calibration fields at the point of test, the spectral neutron fluence rate was determined by means of the Bonner Multi-sphere Spectrometry System (BMSS) and the measured spectra unfolded using the BUNKI code. The dosimetric quantities were derived from the unfolded spectra and used as the reference value to determine the response of each detector. Five kinds of the active detector (three for detector with heavy moderator, one for detector having two spherical tubes with different size, and a TEPC, Tissue Equivalent Proportional Counter) and a TLD as the passive detector were used in this study. The spectral mean energy at the reference calibration points ranged from 0.1 MeV to 3.44 MeV and the dose rate from 0.12 mSv/hr to 4.62 mSv/hr. This paper shows that the big difference, more than four times in case of TLD, in the response of detector with the neutron field spectra should be corrected when the detector is used for monitoring and the dosimetric data of KAERI 's scattered neutron calibration fields. (author)

  15. Benchmark test of TRIPOLI-4 code through simple model calculation and analysis of fusion neutronics experiments at JAEA/FNS

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, Masayuki, E-mail: ohta.masayuki@jaea.go.jp [Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan); Takakura, Kosuke; Ochiai, Kentaro; Sato, Satoshi; Konno, Chikara [Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan)

    2013-10-15

    In order to examine a basic performance of the TRIPOLI code, two types of analyses were carried out with TRIPOLI-4.4 and MCNP5-1.40; one is a simple model calculation and the other is an analysis of iron fusion neutronics experiments with DT neutrons at the Fusion Neutronics Source (FNS) facility in Japan Atomic Energy Agency (JAEA). In the simple model calculation, we adopted a sphere of 0.5 m in radius with a 20 MeV neutron source in the center and calculated leakage neutron spectra from the sphere. We also analyzed in situ and Time-of-Flight (TOF) experiments for iron at JAEA/FNS. For the in situ experiment, neutron spectra and reaction rates for dosimetry reactions were calculated for several points inside the assembly. For the TOF experiment, angular neutron leakage spectra from the assembly were calculated. Results with TRIPOLI were comparable to those with MCNP in most calculations, but a difference between TRIPOLI and MCNP calculation results, probably caused by inadequate treatment of inelastic scattering data in TRIPOLI, appears in some calculations.

  16. Differential Die-Away Instrument: Report on Benchmark Measurements and Comparison with Simulation for the Effects of Neutron Poisons

    Energy Technology Data Exchange (ETDEWEB)

    Goodsell, Alison Victoria [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Swinhoe, Martyn Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Henzl, Vladimir [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rael, Carlos D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Desimone, David J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-30

    In this report, new experimental data and MCNPX simulation results of the differential die-away (DDA) instrument response to the presence of neutron absorbers are evaluated. In our previous fresh nuclear fuel experiments and simulations, no neutron absorbers or poisons were included in the fuel definition. These new results showcase the capability of the DDA instrument to acquire data from a system that better mimics spent nuclear fuel.

  17. Impact of the neutron and nuclear matter equations of state on neutron skin and neutron drip lines in chiral effective field theory

    CERN Document Server

    Sammarruca, Francesca

    2016-01-01

    We present predictions of the binding energy per nucleon and the neutron skin thickness in highly neutron-rich isotopes of Oxygen, Magnesium, and Aluminum. The calculations are carried out at and below the neutron drip line. The nuclear properties are obtained via an energy functional whose input is the equation of state of isospin-asymmetric in?finite matter. The latter is based on a microscopic derivation applying chiral few-nucleon forces. We highlight the impact of the equation of state at diff?erent orders of chiral effective fi?eld theory and discuss the role of three-neutron forces.

  18. Simulated magnetic field expulsion in neutron star cores

    CERN Document Server

    Elfritz, J G; Rea, N; Glampedakis, K; Viganò, D

    2015-01-01

    The study of long-term evolution of neutron star (NS) magnetic fields is key to understanding the rich diversity of NS observations, and to unifying their nature despite the different emission mechanisms and observed properties. Such studies in principle permit a deeper understanding of the most important parameters driving their apparent variety, e.g. radio pulsars, magnetars, x-ray dim isolated neutron stars, gamma-ray pulsars. We describe, for the first time, the results from self-consistent magneto-thermal simulations considering not only the effects of the Hall-driven field dissipation in the crust, but adding a complete set of proposed driving forces in a superconducting core. We emphasize how each of these core-field processes drive magnetic evolution and affect observables, and show that when all forces are considered together in vectorial form, the net expulsion of core magnetic flux is negligible, and will have no observable effect in the crust (consequently in the observed surface emission) on mega...

  19. Experimental possibilities and fast neutron dose map of the fast neutron fields at the RB reactor facility

    International Nuclear Information System (INIS)

    The RB is an unshielded, zero power nuclear facility with natural and enriched uranium fuel (2% and 80%) and D2O as moderator. It is possible to create different configurations of non-reflected and partially reflected critical systems and to make experiments in the fields of thermal neutrons. The fields of fast neutrons with 'softened' fission spectrum are made by modifying the system: modified experimental fuel channel EFC, coupled fast-thermal system in two configurations CFTS-1 and CFTS-2, coupled fast-thermal core HERBE. The intermediate and fast neutron absorbed doses in fast neutron fields are given. In first configuration of RB reactor it was almost impossible to perform dosimetric and other experiments. By creating these fields, with in our circumstances available fuel elements, the possibilities for different experiments are greatly improved. Now we can irradiate food samples, soil samples, electronic devices, study material properties, perform various dosimetry experiments, etc. (1 tab.)

  20. Neutron star in the presence of strong magnetic field

    Indian Academy of Sciences (India)

    K K Mohanta; R Mallick; N R Panda; L P Singh; P K Sahu

    2014-05-01

    Compact stars such as neutron stars (NS) can have either hadronic or exotic states like strange quark or colour superconducting matter. Stars can also have a quark core surrounded by hadronic matter, known as hybrid stars (HS). The HS is likely to have a mixed phase in between the hadron and the quark phases. Observational results suggest huge surface magnetic field in certain NS. Therefore, we study here the effect of strong magnetic field on the respective equation of states (EOS) of matter under extreme conditions. We further study the hadron–quark phase transition in the interiors of NS giving rise to HS in the presence of strong magnetic field. The hadronic matter EOS is described based on RMF theory and we include the effects of strong magnetic fields leading to Landau quantization of the charged particles. For quark phase, we use the simple Massachusetts Institute of Technology (MIT) bag model, assuming density-dependent bag pressure and magnetic field. The magnetic field strength increases from the surface to the centre of the star. We construct the intermediate mixed phase using Glendenning conjecture. The magnetic field softens the EOS of both the matter phases. We finally study, the mass–radius relationship for such types of mixed HS, calculating their maximum mass, and compare them with the recent observations of pulsar PSR J1614-2230, which is about 2 solar mass.

  1. Measurement of quantum states of neutrons in the Earth's gravitational field

    OpenAIRE

    Nesvizhevsky, V. V.; Boerner, H. G.; Gagarsky, A. M.; Petoukhov, A. K.; Petrov, G. A.; Abele, H; Baessler, S.; Divkovic, G.; Ruess, F. J.; Stoeferle, Th.; Westphal, A.; Strelkov, A. V.; Protasov, K. V.; Voronin, A. Yu.

    2003-01-01

    The lowest stationary quantum state of neutrons in the Earth's gravitational field is identified in the measurement of neutron transmission between a horizontal mirror on the bottom and an absorber on top. Such an assembly is not transparent for neutrons if the absorber height is smaller than the "height" of the lowest quantum state.

  2. Growth of the Magnetic Field in Young Neutron Stars

    CERN Document Server

    Negreiros, Rodrigo

    2015-01-01

    Rotation Powered-Pulsars are subjected to long-term changes in their period of rotation, which are measured by timing observations of their rotation frequency and its derivatives ($\\Omega$, $\\dot{\\Omega}$, $\\ddot{\\Omega}$). If the spin-down is solely due to dipolar radiation, the braking index should be $n=3$. To date, only a handful of braking indices have been estimated for young pulsars, and in all cases one observes that $n<3$. These observations suggest that there are complex spin-down processes taking place in the pulsar that are not fully well understood. In the present work we revisit the spin-down of young pulsars by considering a possible magnetic field growth due ohmic diffusion. In order to perform such study we perform calculations with phenomenological growth functions for the magnetic field. With that we are able to calculate the spin evolution of the neutron star with all relevant quantities. We show that such approach could explain the low values of $n$ in very young neutron stars and may ...

  3. Electrical conductivity of warm neutron star crust in magnetic fields

    CERN Document Server

    Harutyunyan, Arus

    2016-01-01

    We study the electrical conductivity of finite-temperature crust of a warm compact star which may be formed in the aftermath of a supernova explosion or a binary neutron star merger as well as when a cold neutron star is heated by accretion of material from a companion. We focus on the temperature-density regime where plasma is in the liquid state and, therefore, the conductivity is dominated by the electron scattering off correlated nuclei. The dynamical screening of this interaction is implemented in terms of polarization tensor computed in the hard-thermal-loop effective field theory of QED plasma. The correlations of the background ionic component are accounted for via a structure factor derived from Monte-Carlo simulations of one-component-plasma. With this input we solve the Boltzmann kinetic equation in relaxation time approximation taking into account the anisotropy of transport due to the magnetic field. The electrical conductivity tensor is studied numerically as a function of temperature and densit...

  4. Experimental study of the neutronics of the first gas cooled fast reactor benchmark assembly (GCFR phase I assembly)

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, S.K.

    1976-12-01

    The Gas Cooled Fast Reactor (GCFR) Phase I Assembly is the first in a series of ZPR-9 critical assemblies designed to provide a reference set of reactor physics measurements in support of the 300 MW(e) GCFR Demonstration Plant designed by General Atomic Company. The Phase I Assembly was the first complete mockup of a GCFR core ever built. A set of basic reactor physics measurements were performed in the assembly to characterize the neutronics of the assembly and assess the impact of the neutron streaming on the various integral parameters. The analysis of the experiments was carried out using ENDF/B-IV based data and two-dimensional diffusion theory methods. The Benoist method of using directional diffusion coefficients was used to treat the anisotropic effects of neutron streaming within the framework of diffusion theory. Calculated predictions of most integral parameters in the GCFR showed the same kinds of agreements with experiment as in earlier LMFBR assemblies.

  5. Neutron assay in mixed radiation fields with a 6Li-loaded plastic scintillator

    International Nuclear Information System (INIS)

    A novel technique for assay of thermal and fast neutrons in a 6Li-loaded plastic scintillator is presented. Existing capture-gated thermal neutron detection techniques were evaluated with the 6Li-loaded plastic scintillator studied in this work. Using simulations and experimental work, shortcomings in its performance were highlighted. As a result, it was proposed that by separating the combined fast and thermal neutron events from gamma events, using established pulse shape discrimination techniques, the thermal neutron events could then be assayed. Experiments were conducted at the National Physical Laboratory, Teddington, performing neutron assays with seven different neutron fields using the proposed technique. For each field, thermal and fast neutron content was estimated and were shown to corroborate with the seven synthesised fields

  6. New Multi-group Transport Neutronics (PHISICS) Capabilities for RELAP5-3D and its Application to Phase I of the OECD/NEA MHTGR-350 MW Benchmark

    Energy Technology Data Exchange (ETDEWEB)

    Gerhard Strydom; Cristian Rabiti; Andrea Alfonsi

    2012-10-01

    PHISICS is a neutronics code system currently under development at the Idaho National Laboratory (INL). Its goal is to provide state of the art simulation capability to reactor designers. The different modules for PHISICS currently under development are a nodal and semi-structured transport core solver (INSTANT), a depletion module (MRTAU) and a cross section interpolation (MIXER) module. The INSTANT module is the most developed of the mentioned above. Basic functionalities are ready to use, but the code is still in continuous development to extend its capabilities. This paper reports on the effort of coupling the nodal kinetics code package PHISICS (INSTANT/MRTAU/MIXER) to the thermal hydraulics system code RELAP5-3D, to enable full core and system modeling. This will enable the possibility to model coupled (thermal-hydraulics and neutronics) problems with more options for 3D neutron kinetics, compared to the existing diffusion theory neutron kinetics module in RELAP5-3D (NESTLE). In the second part of the paper, an overview of the OECD/NEA MHTGR-350 MW benchmark is given. This benchmark has been approved by the OECD, and is based on the General Atomics 350 MW Modular High Temperature Gas Reactor (MHTGR) design. The benchmark includes coupled neutronics thermal hydraulics exercises that require more capabilities than RELAP5-3D with NESTLE offers. Therefore, the MHTGR benchmark makes extensive use of the new PHISICS/RELAP5-3D coupling capabilities. The paper presents the preliminary results of the three steady state exercises specified in Phase I of the benchmark using PHISICS/RELAP5-3D.

  7. International key comparison of neutron fluence measurements in monoenergetic neutron fields: CCRI(III)-K11

    Science.gov (United States)

    Gressier, V.; Bonaldi, A. C.; Dewey, M. S.; Gilliam, D. M.; Harano, H.; Masuda, A.; Matsumoto, T.; Moiseev, N.; Nico, J. S.; Nolte, R.; Oberstedt, S.; Roberts, N. J.; Röttger, S.; Thomas, D. J.

    2014-01-01

    To ensure the validity of their national standards, National Metrology Institutes (NMIs) participate regularly in international comparisons. In the area of neutron metrology, Section III of the Consultative Committee for Ionizing Radiation is in charge of the organization of these comparisons. From September 2011 to October 2012, the eleventh key comparison, named CCRI(III)-K11, took place at the AMANDE facility of the LNE-IRSN, in France. Participants from nine NMIs came with their own primary reference instruments, or instruments traceable to primary standards, with the aim of determining the neutron fluence, at 1 m distance from the target in vacuum, per monitor count at four monoenergetic neutron fields: 27 keV, 565 keV, 2.5 MeV and 17 MeV. The key comparison reference values (KCRV) were evaluated as the weighted mean values of the results provided by seven participants. The uncertainties of each KCRV are between 0.9% and 1.7%. The degree of equivalence (DoE), defined as the deviation of the result reported by the laboratories for each energy from the corresponding KCRV, and the associated expanded uncertainty are also reported and discussed. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  8. New integral experiments for large angle scattering cross section data benchmarking with DT neutron beam at JAEA/FNS

    Energy Technology Data Exchange (ETDEWEB)

    Ohnishi, Seiki, E-mail: ohnishi@nmri.go.jp [National Maritime Research Institute, Mitaka, Tokyo (Japan); Kondo, Keitaro [Japan Atomic Energy Agency, Tokai-mura, Ibaraki (Japan); Azuma, Tetsushi [Kyoto University, Kumatori-cho, Osaka (Japan); Sato, Satoshi; Ochiai, Kentaro; Takakura, Kosuke [Japan Atomic Energy Agency, Tokai-mura, Ibaraki (Japan); Murata, Isao [Osaka University, Suita, Osaka (Japan); Konno, Chikara [Japan Atomic Energy Agency, Tokai-mura, Ibaraki (Japan)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer We constructed a deuteron-triton fusion neutron beam. Black-Right-Pointing-Pointer A large SS316 cylinder assembly was irradiated by the neutron beam. Black-Right-Pointing-Pointer The reaction rates of activation foil were measured inside it. Black-Right-Pointing-Pointer The C/Es became smaller with the distance from the beam axis. Black-Right-Pointing-Pointer The large angle scattering cross section around 90 Degree-Sign affects that. - Abstract: A new integral experiment with a deuteron-triton fusion (DT) neutron beam started in order to validate scattering cross section data. First the DT neutron beam was constructed with a collimator. The performance of the collimator system and the characteristics of the DT neutron beam were measured. Second a new integral experiment for type 316 stainless steel (SS316) was carried out with this DT neutron beam. The DT neutron beam of 3.5 cm in diameter was injected to the front surface center of an SS316 cylindrical assembly. Reaction rates of the {sup 93}Nb(n,2n){sup 92m}Nb reaction in the assembly were measured with the activation foil method and were calculated with the Monte Carlo transport calculation code. The measurement points were located at three positions, on the center of the beam axis and at 15 cm and 30 cm apart from the axis. The ratio of calculation to experiment of the {sup 93}Nb(n,2n){sup 92m}Nb reaction rate became smaller than 1 with the distance from the beam axis. Then, the dependency of each reaction rate on scattering angle was calculated. It was proved that at off-axis positions, where C/E is smaller than 1, 90 Degree-Sign scattering contribute relatively larger than at on-axis positions and backward scattering made little contribution to the results in this experiment. The reasons of the discrepancy between the measured and calculated data will be investigated.

  9. Characteristics of the KUR Heavy Water Neutron Irradiation Facility as a neutron irradiation field with variable energy spectra

    Science.gov (United States)

    Sakurai, Yoshinori; Kobayashi, Tooru

    2000-10-01

    The Heavy Water Neutron Irradiation Facility (HWNIF) of the Kyoto University Research Reactor (KUR) was updated in March 1996, mainly for the improvement in neutron capture therapy (NCT). A striking feature of the updated facility is that the energy spectrum of the neutron beam can be controlled from almost pure thermal to epi-thermal, within 5 min by remote control under a continuous reactor operation. This feature is advantageous not only to medical science such as NCT, but also to the other research fields such as physics, engineering, biology, etc. The performance of the updated facility as a neutron irradiation field with variable energy spectra, was characterized. Thermal neutron flux, cadmium ratio, gamma-ray dose rate, etc., at the normal irradiation position for various irradiation modes were determined, mainly on the basis of the measurement using gold activation foils and thermo-luminescent dosimeters (TLDs). The emphasis was on the performance of the new neutron energy spectrum shifter and cadmium thermal neutron filter, that control the mixing ratio of thermal and epi-thermal neutrons, through the change in the heavy water thickness of the spectrum shifter and the aperture size of the cadmium filter. The evaluation of neutron energy spectra at the normal irradiation position was also performed for three representative irradiation modes, in which the neutron intensities are largest of all the irradiation modes. In addition, the irradiation characteristics of two irradiation devices, namely the Irradiation Rail Device and the Remote Patient Carrier, which were updated concurrently with the facility update, were evaluated.

  10. Gravitationally enhanced depolarization of ultracold neutrons in magnetic field gradients, and implications for neutron electric dipole moment measurements

    CERN Document Server

    Harris, P G; Devenish, N E

    2014-01-01

    Trapped ultracold neutrons (UCN) have for many years been the mainstay of experiments to search for the electric dipole moment (EDM) of the neutron, a critical parameter in constraining scenarios of new physics beyond the Standard Model. Because their energies are so low, UCN preferentially populate the lower region of their physical enclosure, and do not sample uniformly the ambient magnetic field throughout the storage volume. This leads to a substantial increase in the rate of depolarization, as well as to shifts in the measured frequency of the stored neutrons. Consequences for EDM measurements are discussed.

  11. Characterisation of Laboratory-produced CANDU(r)-like workplace neutron fields

    International Nuclear Information System (INIS)

    Two neutron fields were produced in the Neutron Irradiation Facility (NIF) at the Chalk River Laboratories of the Atomic Energy of Canada Ltd. by direction (d,D) neutrons from a 150 kV neutron generator through a specially designed moderator assembly. Bonner sphere and proton recoil spectrometry systems were used to characterise these fields to determine whether they were CANDU(r)-like, i.e. whether they resembled neutron fields found in workplaces around pressurised heavy-water moderated power reactors such as CANDU(r) reactors. Similarities were found between the distributions in energy of neutron fluence and ambient dose equivalent of the neutron fields produced in the NIF and those measured previously in power plants. In addition, there was agreement between theoretical (Monte Carlo) data and measured data, thereby validating continued use of Monte Carlo modelling for field characterisations in the NIF. The CANDU(r)-like fields add to the repertoire of neutron fields available in the NIF and are expected to be useful for evaluating neutron dosemeters. (author)

  12. Experimental and numerical characterization of the neutron field produced in the n@BTF Frascati photo-neutron source

    OpenAIRE

    Bedogni, R.; Quintieri, L; Buonomo, B.; Esposito, A.; Mazzitelli, G.; Foggetta, L.; Gomez Ros. J.M.

    2011-01-01

    A photo-neutron irradiation facility is going to be established at the Frascati National Laboratories of INFN on the base of the successful results of the n@BTF experiment. The photoneutron source is obtained by an electron or positron pulsed beam, tunable in energy, current and in time structure, impinging on an optimized tungsten target located in a polyethylene-lead shielding assembly. The resulting neutron field, through selectable collimated apertures at different angles, is released int...

  13. Review of neutron calibration facilities and monitoring techniques: new needs for emerging fields.

    Science.gov (United States)

    Gressier, V

    2014-10-01

    Neutron calibration facilities and monitoring techniques have been developed since the middle of the 20th century to support research and nuclear power energy development. The technical areas needing reference neutron fields and related instruments were mainly cross section measurements, radiation protection, dosimetry and fission reactors, with energy ranging from a few millielectronvolts to about 20 MeV. The reference neutron fields and calibration techniques developed for these purposes will be presented in this paper. However, in recent years, emerging fields have brought new needs for calibration facilities and monitoring techniques. These new challenges for neutron metrology will be exposed with their technical difficulties.

  14. Quantitative Neutron Dark-field Imaging through Spin-Echo Interferometry

    OpenAIRE

    Markus Strobl; Morten Sales; Jeroen Plomp; Bouwman, Wim G.; Tremsin, Anton S.; Anders Kaestner; Catherine Pappas; Klaus Habicht

    2015-01-01

    Neutron dark-field imaging constitutes a seminal progress in the field of neutron imaging as it combines real space resolution capability with information provided by one of the most significant neutron scattering techniques, namely small angle scattering. The success of structural characterizations bridging the gap between macroscopic and microscopic features has been enabled by the introduction of grating interferometers so far. The induced interference pattern, a spatial beam modulation, a...

  15. DEVELOPMENT OF SIMULATED WORKPLACE FIELDS AT KRISS FOR PERFORMANCE TEST OF NEUTRON PERSONAL DOSEMETERS.

    Science.gov (United States)

    Kim, Jungho; Park, Hyeonseo; Kim, Yunho

    2016-09-01

    Simulated workplace neutron fields have been developed at the Korea Research Institute of Standards and Science (KRISS). An (241)Am-Be neutron source and a cylindrical moderator composed of stainless steel and heavy water were installed in a 10-cm-thick concrete block with dimensions of 150 × 120 × 120 cm(3) The neutron energy spectrum at a distance of 66.5 cm was measured using a Bonner sphere spectrometer and was found to agree with the spectrum obtained from the Monte Carlo N-Particle Extended simulation to within 5 %. The neutron fluence-to-personal dose equivalent conversion coefficients were (20.8-43.6) pSv·cm(2) and were thus in good agreement with those of reactor fields. The results showed that the KRISS-simulated workplace neutron fields can be used for performance tests and the calibration service of neutron personal dosemeters. PMID:26541186

  16. Experimental investigations of the neutron contamination in high-energy photon fields at medical linear accelerators

    International Nuclear Information System (INIS)

    The scope of this thesis was to develop a device for the detection of the photoneutron dose inside the high-energy photon field. The photoneutron contamination of a Siemens PRIMUS linear accelerator was investigated in detail in its 15 MV photon mode. The experimental examinations were performed with three ionisation chambers (a tissue equivalent chamber, a magnesium chamber and a 10B-coated magnesium chamber) and two types of thermoluminescence detectors (enriched with 6Li and 7Li, respectively). The detectors have different sensitivities to photons and neutrons and their combination allows the dose separation in a mixed neutron/photon field. The application of the ionisation chamber system, as well as the present TLD system for photoneutron detection in high-energy photon beams is a new approach. The TLD neutron sensitivity was found to be too low for a measurement inside the open photon field and the further investigation focused on the ionisation chambers. The three ionisation chambers were calibrated at different photon and neutron sources and a the borated magnesium chamber showed a very high response to thermal neutrons. For a cross check of the calibration, the three chambers were also used for dose separation of a boron neutron capture therapy beam where the exact determination of the thermal neutron dose is essential. Very accurate results were achieved for the thermal neutron dose component. At the linear accelerator the chamber system was reduced to a paired chamber system utilising the two magnesium chambers, since the fast neutron component was to small to be separated. The neutron calibration of the three chambers could not be applied, instead a conversion of measured thermal neutron signal by the borated chamber to Monte Carlo simulated total neutron dose was performed. Measurements for open fields in solid water and liquid water were performed with the paired chamber system. In larger depths the neutron dose could be determined with an uncertainty

  17. Experimental investigations of the neutron contamination in high-energy photon fields at medical linear accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Brunckhorst, Elin

    2009-02-26

    The scope of this thesis was to develop a device for the detection of the photoneutron dose inside the high-energy photon field. The photoneutron contamination of a Siemens PRIMUS linear accelerator was investigated in detail in its 15 MV photon mode. The experimental examinations were performed with three ionisation chambers (a tissue equivalent chamber, a magnesium chamber and a {sup 10}B-coated magnesium chamber) and two types of thermoluminescence detectors (enriched with {sup 6}Li and {sup 7}Li, respectively). The detectors have different sensitivities to photons and neutrons and their combination allows the dose separation in a mixed neutron/photon field. The application of the ionisation chamber system, as well as the present TLD system for photoneutron detection in high-energy photon beams is a new approach. The TLD neutron sensitivity was found to be too low for a measurement inside the open photon field and the further investigation focused on the ionisation chambers. The three ionisation chambers were calibrated at different photon and neutron sources and a the borated magnesium chamber showed a very high response to thermal neutrons. For a cross check of the calibration, the three chambers were also used for dose separation of a boron neutron capture therapy beam where the exact determination of the thermal neutron dose is essential. Very accurate results were achieved for the thermal neutron dose component. At the linear accelerator the chamber system was reduced to a paired chamber system utilising the two magnesium chambers, since the fast neutron component was to small to be separated. The neutron calibration of the three chambers could not be applied, instead a conversion of measured thermal neutron signal by the borated chamber to Monte Carlo simulated total neutron dose was performed. Measurements for open fields in solid water and liquid water were performed with the paired chamber system. In larger depths the neutron dose could be determined

  18. The response of the BTI bubble detectors in mixed gamma-neutron workplace fields

    International Nuclear Information System (INIS)

    Bubble detectors have become a mature technology and are used as neutron dosemeters in a wide range of applications. At the SCK-CEN and Belgonucleaire they are used as official personal neutron dosemeter for the personnel. In the European Commission (EC) project of Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields (EVIDOS), a whole range of neutron dosemeters were irradiated in workplace fields in nuclear installations in Europe, including two types of bubble detectors. The responses of the bubble detectors are compared with the reference values determined using a directional spectrometer and a reference instrument to measure Hp(10). (authors)

  19. Powerful pulsed neutron sources for research with a pulsed magnetic field

    International Nuclear Information System (INIS)

    The prospects for neutron investigations into the magnetic properties of condensed matter with the use of powerful pulsed neutron sources [Japan Spallation Neutron Source (JSNS) (Tokai, Japan), TIRAN (Zababakhin All-Russia Research Institute of Technical Physics, Russian Federal Nuclear Center, Snezhinsk, Russia), Large Hadron Collider (LHC) (CERN)] and pulsed magnetic fields are considered. It is demonstrated that the diffraction measurements of the magnetic states induced by a magnetic field of up to 700-1000 kOe can be performed at the TIRAN reactor and the neutron source that can be developed on the basis of the LHC accelerator.

  20. Response of neutron dosimeters to pulsed neutron fields in high energy electron accelerators at Indus Complex, RRCAT

    International Nuclear Information System (INIS)

    Indus Accelerator Complex (IAC) comprises of two high energy electron accelerators namely Indus-1 SRS (450 MeV) and Indus-2 SRS (2.5 GeV). The radiation environment present is mainly due to Bremsstrahlung Photons and Photo- neutrons produced due to interaction of high-energy electrons with the structural material of accelerators. Since electron beam is pulsed in nature, the radiations produced are also pulsed. The response of commonly used Rem meters is not proper in severely pulsed neutron fields at high dose rates. They tend to underestimate the actual dose. Due to this uncertainty, an attempt was made to study the response of passive integrating type detectors in the pulsed neutron fields found in high energy electron accelerators to get an idea about the ambient neutron field in IAC. The detectors used were CR-39 foils (provided by PMS, RPAD and RSSD, BARC), Bubble Detectors (provided by Defence Laboratory, Jodhpur) and Rem Meter. Neutron dose assessment in both, accessible and inaccessible areas of IAC was carried out using these detectors and the present paper gives the results of preliminary experiments performed. (author)

  1. Internal composition of proto-neutron stars under strong magnetic fields

    Science.gov (United States)

    Franzon, B.; Dexheimer, V.; Schramm, S.

    2016-08-01

    In this work, we study the effects of magnetic fields and rotation on the structure and composition of proto-neutron stars. A hadronic chiral SU(3) model is applied to cold neutron stars and proto-neutron stars with trapped neutrinos and at fixed entropy per baryon. We obtain general relativistic solutions for neutron and proto-neutron stars endowed with a poloidal magnetic field by solving Einstein-Maxwell field equations in a self-consistent way. As the neutrino chemical potential decreases in value over time, this alters the chemical equilibrium and the composition inside the star, leading to a change in the structure and in the particle population of these objects. We find that the magnetic field deforms the star and significantly alters the number of trapped neutrinos in the stellar interior, together with strangeness content and temperature in each evolution stage.

  2. PADC Detected External Neutron Field by Nuclear Tracks at RFX-mod

    Directory of Open Access Journals (Sweden)

    W. Gonzalez

    2014-08-01

    Full Text Available Measured neutron signals relevant for plasma diagnostics on Reversed Field pinch eXperiment, RFX-mod, are obtained by nuclear track methodology with PADC-NTD’s. This technique provides the external neutron field values around the RFX-mod installation during pulsed operation. Charged particles from (n, p and (n, α reactions are related to formed latent tracks. These are etched in a thermoregulated water bath with a 6.25M, KOH solution at 60o C. Observed tracks were analyzed to determine track density from which neutron fluence spatial values should be derived. Results indicate that the neutron density in the surrounding environment change at most 40%. The epithermal component is 60% higher than that corresponding to the thermal region. The estimated neutron fluence for the whole experiment is 7.5×1010 neutrons cm2 /s.

  3. 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).

  4. Evaluation of neutronic characteristic of irradiation field in MEU6-core. Comparison of neutron flux and neutron spectrum in MEU6-core and Mixed-core

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Yoshiharu; Komukai, Bunsaku; Tabata, Toshio; Takeda, Takashi; Fujiki, Kazuo [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment

    1999-08-01

    In JMTR (Japan Materials Testing Reactor, 50 MW), the core configuration has been changed from previously employed Mixed-core (25 LEUs(low enrichment uranium (19.8%) fuel elements) and 2 MEUs (medium enrichment uranium (45%) fuel elements)) to MEU6-core (21 LEUs and 6 MEUs), since 125th operating cycle (started in Nov. 17, 1998). In order to investigate the effect of core configuration change on the irradiation tests, neutron flux distribution and neutron spectrum of irradiation field in MEU6-core were calculated by diffusion code CITATION and Monte Carlo code MCNP. As the result, it was confirmed that irradiation field in the MEU6-core has the neutronic characteristics almost equivalent to the irradiation field in the Mixed-core. (author)

  5. Production of neutron cross section library based on JENDL-4.0 to continuous-energy Monte Carlo code MVP and its application to criticality analysis of benchmark problems in the ICSBEP handbook

    International Nuclear Information System (INIS)

    In May 2010, JENDL-4.0 was released from Japan Atomic Energy Agency as the updated Japanese Nuclear Data Library. It was processed by the nuclear data processing system LICEM and an arbitrary-temperature neutron cross section library MVPlib-nJ40 was produced for the neutron and photon transport calculation code MVP based on the continuous-energy Monte Carlo method. The library contains neutron cross sections for 406 nuclides on the free gas model, thermal scattering cross sections, and cross sections of pseudo fission products for burn-up calculations with MVP. Criticality benchmark calculations were carried out with MVP and MVPlib-nJ40 for about 1,000 cases of critical experiments stored in the hand book of International Criticality Safety Benchmark Evaluation Project (ICSBEP), which covers a wide variety of fuel materials, fuel forms, and neutron spectra. We report all comparison results (C/E values) of effective neutron multiplication factors between calculations and experiments to give a validation data for the prediction accuracy of JENDL-4.0 for criticalities. (author)

  6. Monte-Carlo simulation of cement neutron field distribution characteristics in PGNAA

    International Nuclear Information System (INIS)

    The distribution characteristics of the neutron field in cement was simulated using the MCNP code to comply with the requirements of an online Prompt Gamma Neutron Activation Analysis system. Simulation results showed that the neutron relative flux proportion reduced with increasing cement thickness. When the cement thickness remains unchanged, the reduced proportion of thermal neutrons increases to a small extent, but the epithermal, intermediate, and fast neutrons will decrease according to the geometric progression. H element in the cement mainly affects the reduction of fast neutrons and other single-substance elements, e.g., O, Ca, 56Fe, Si, and Al. It also slows down the reduction of the fast neutrons via inelastic scattering. O contributes more than other elements in the reduction of fast neutrons. Changing the H content affects the thermal, epithermal, intermediate, and fast neutrons, while changing the Ca, Fe, and Si contents only influences the thermal, epithermal, and intermediate neutrons; hence, there is little effect on the reduction of fast neutrons. (authors)

  7. Elusive Neutrons from Nuclei in Effective Field Theory

    OpenAIRE

    Beane, Silas R.

    1999-01-01

    We review recent computations of neutral pion photoproduction and Compton scattering on the deuteron in baryon chiral perturbation theory. Progress in extracting the neutron electric dipole amplitude, which is relevant in neutral pion photoproduction, and the neutron polarizabilities, which are relevant in Compton scattering, is discussed.

  8. Neutron Scattering at Highest Magnetic Fields at the Helmholtz Centre Berlin

    Science.gov (United States)

    Smeibidl, P.; Tennant, A.; Ehmler, H.; Bird, M.

    2010-04-01

    The Helmholtz Centre Berlin (HZB), formerly Hahn-Meitner Institute is a user facility for the study of structure and dynamics with neutrons and synchrotron radiation with special emphasis on experiments under extreme conditions. Neutron scattering is uniquely suited to study magnetic properties on a microscopic length scale, because neutrons have comparable wavelengths and, due to their magnetic moment, they interact with the atomic magnetic moments. At HZB a dedicated instrument for neutron scattering at extreme fields is under construction, the Extreme Environment Diffractometer ExED. It is projected according to the “time-of-flight” principle for elastic and inelastic neutron scattering and for the special geometric constraints of analysing samples in a high field magnet. The new magnet will not only allow for novel experiments, it will be at the forefront of development in magnet technology itself. The design of the magnet will follow the Series Connected Hybrid System Technology (SCH) developed at the National High Magnetic Field Laboratory (NHMFL) in Tallahassee, Florida. To compromise between the needs of the magnet design for highest fields and the concept of the neutron instrument, the magnetic field will be generated by means of a coned solenoid with horizontal field orientation. By using resistive insert coils, which are mounted in the room temperature bore of a superconducting cable-in-conduit (CIC) magnet, fields above 30 Tesla can be obtained in a geometry optimised for the demands of neutron scattering.

  9. A field-based method to derive macroinvertebrate benchmark for specific conductivity adapted for small data sets and demonstrated in the Hun-Tai River Basin, Northeast China.

    Science.gov (United States)

    Zhao, Qian; Jia, Xiaobo; Xia, Rui; Lin, Jianing; Zhang, Yuan

    2016-09-01

    Ionic mixtures, measured as specific conductivity, have been increasingly concerned because of their toxicities to aquatic organisms. However, identifying protective values of specific conductivity for aquatic organisms is challenging given that laboratory test systems cannot examine more salt-intolerant species nor effects occurring in streams. Large data sets used for deriving field-based benchmarks are rarely available. In this study, a field-based method for small data sets was used to derive specific conductivity benchmark, which is expected to prevent the extirpation of 95% of local taxa from circum-neutral to alkaline waters dominated by a mixture of SO4(2-) and HCO3(-) anions and other dissolved ions. To compensate for the smaller sample size, species level analyses were combined with genus level analyses. The benchmark is based on extirpation concentration (XC95) values of specific conductivity for 60 macroinvertebrate genera estimated from 296 sampling sites in the Hun-Tai River Basin. We derived the specific conductivity benchmark by using a 2-point interpolation method, which yielded the benchmark of 249 μS/cm. Our study tailored the method that was developed by USEPA to derive aquatic life benchmark for specific conductivity for basin scale application, and may provide useful information for water pollution control and management.

  10. Dose Determination using alanine detectors in a Mixed Neutron and Gamma Field for Boron Neutron Capture Therapy of Liver Malignancies

    DEFF Research Database (Denmark)

    Schmitz, T.; Blaickner, M.; Ziegner, M.;

    2011-01-01

    Introduction Boron Neutron Capture Therapy for liver malignancies is being investigated at the University of Mainz. One important aim is the set-up of a reliable dosimetry system. Alanine dosimeters have previously been applied for dosimetry of mixed radiation fields in antiproton therapy, and may...

  11. Comparative Neutronics Analysis of DIMPLE S06 Criticality Benchmark with Contemporary Reactor Core Analysis Computer Code Systems

    Directory of Open Access Journals (Sweden)

    Wonkyeong Kim

    2015-01-01

    Full Text Available A high-leakage core has been known to be a challenging problem not only for a two-step homogenization approach but also for a direct heterogeneous approach. In this paper the DIMPLE S06 core, which is a small high-leakage core, has been analyzed by a direct heterogeneous modeling approach and by a two-step homogenization modeling approach, using contemporary code systems developed for reactor core analysis. The focus of this work is a comprehensive comparative analysis of the conventional approaches and codes with a small core design, DIMPLE S06 critical experiment. The calculation procedure for the two approaches is explicitly presented in this paper. Comprehensive comparative analysis is performed by neutronics parameters: multiplication factor and assembly power distribution. Comparison of two-group homogenized cross sections from each lattice physics codes shows that the generated transport cross section has significant difference according to the transport approximation to treat anisotropic scattering effect. The necessity of the ADF to correct the discontinuity at the assembly interfaces is clearly presented by the flux distributions and the result of two-step approach. Finally, the two approaches show consistent results for all codes, while the comparison with the reference generated by MCNP shows significant error except for another Monte Carlo code, SERPENT2.

  12. Neutron Crystal-Field Spectroscopy and Susceptibility in ErcY1-cA1

    DEFF Research Database (Denmark)

    Heer, H.; Furrer, A.; Walker, E.;

    1974-01-01

    Inelastic neutron scattering experiments and susceptibility measurements have been carried out on polycrystalline ErcY1-cAl2. A least-squares fitting procedure has been applied to the neutron data which favours four sets of crystal-field parameters. The results are compared with the measured susc...

  13. Polarisation Analysis Neutron Spectrometer, POLANO, at J-PARC - Concept and Magnetic Field Optimisation

    Science.gov (United States)

    Ohoyama, K.; Yokoo, T.; Itoh, S.; Nanbu, M.; Iwasa, K.; Ohkawara, M.; Kaneko, N.; Ino, T.; Hayashida, H.; Oku, T.; Kira, H.; Tasaki, S.; Takeda, M.; Kimura, H.; Sato, T. J.

    2016-04-01

    The status of the polarised neutron spectrometer constructed at the Japan Proton Accelerator Research Complex through a collaboration between Tohoku University and KEK will be reported. In particular, the optimisation of magnetic fields to minimise neutron- beam depolarisation using the finite element method will be discussed on the basis of several simulations using the finite element method.

  14. Axial distribution of absorbed doses in fast neutron field at the RB reactor

    International Nuclear Information System (INIS)

    The coupled fast thermal system CFTS at the RB reactor is created for obtaining fast neutron fields. The axial distribution of fast neutron flux density in its second configuration (CFTS-2) is measured. The axial distribution of absorbed doses is computed on the basis of mentioned experimental results. At the end these experimental and computed results are given. (Author)

  15. Quantification of the sensitivity range in neutron dark-field imaging

    Energy Technology Data Exchange (ETDEWEB)

    Betz, B.; Harti, R. P.; Hovind, J.; Kaestner, A.; Lehmann, E.; Grünzweig, C. [Paul Scherrer Institute, LNS, Neutron Imaging and Activation Group, CH-5232 Villigen (Switzerland); Strobl, M. [European Spallation Source ESS, 22100 Lund, Sweden and University of Copenhagen, 2100 Copenhagen (Denmark); Van Swygenhoven, H. [Ecole Polytechnique Fédérale de Lausanne, NXMM Laboratory, IMX, CH-1015 Lausanne, Switzerland and Paul Scherrer Institut, NXMM, CH-5232 Villigen (Switzerland)

    2015-12-15

    In neutron grating interferometry, the dark-field image visualizes the scattering properties of samples in the small-angle and ultra-small-angle scattering range. These angles correspond to correlation lengths from several hundred nanometers up to several tens of micrometers. In this article, we present an experimental study that demonstrates the potential of quantitative neutron dark-field imaging. The dark-field signal for scattering from different particle sizes and concentrations of mono-dispersive polystyrene particles in aqueous solution is compared to theoretical predictions and the good agreement between measurements and calculations underlines the quantitative nature of the measured values and reliability of the technique with neutrons.

  16. Auxiliary-Field Quantum Monte Carlo Simulations of Neutron Matter in Chiral Effective Field Theory

    CERN Document Server

    Wlazłowski, G; Moroz, S; Bulgac, A; Roche, K J

    2014-01-01

    We present variational Monte Carlo calculations of the neutron matter equation of state using chiral nuclear interactions. The ground-state wavefunction of neutron matter, containing non-perturbative many-body correlations, is obtained from auxiliary-field quantum Monte Carlo simulations of up to about 340 neutrons interacting on a 10^3 discretized lattice. The evolution Hamiltonian is chosen to be attractive and spin-independent in order to avoid the fermion sign problem and is constructed to best reproduce broad features of chiral nuclear forces. This is facilitated by choosing a lattice spacing of 1.5 fm, corresponding to a momentum-space cutoff of 414 MeV/c, a resolution scale at which strongly repulsive features of nuclear two-body forces are suppressed. Differences between the evolution potential and the full chiral nuclear interaction are then treated perturbatively. Our results for the equation of state are compared to previous quantum Monte Carlo simulations which employed chiral two-body forces at n...

  17. Neutron Star Structure in the Presence of Conformally Coupled Scalar Fields

    Science.gov (United States)

    Sultana, Joseph; Bose, Benjamin; Kazanas, Demosthenes

    2014-01-01

    Neutron star models are studied in the context of scalar-tensor theories of gravity in the presence of a conformally coupled scalar field, using two different numerical equations of state (EoS) representing different degrees of stiffness. In both cases we obtain a complete solution by matching the interior numerical solution of the coupled Einstein-scalar field hydrostatic equations, with an exact metric on the surface of the star. These are then used to find the effect of the scalar field and its coupling to geometry, on the neutron star structure, particularly the maximum neutron star mass and radius. We show that in the presence of a conformally coupled scalar field, neutron stars are less dense and have smaller masses and radii than their counterparts in the minimally coupled case, and the effect increases with the magnitude of the scalar field at the center of the star.

  18. Skyrme model study of proton and neutron properties in a strong magnetic field

    CERN Document Server

    He, Bing-Ran

    2016-01-01

    The proton and neutron properties in a uniform magnetic field are investigated. The Gell-Mann-Nishijima formula is shown to be satisfied for baryon states. It is found that with increasing magnetic field strength, the proton mass first decreases and then increases, while the neutron mass always increases. The ratio between magnetic moment of proton and neutron increases with the increase of the magnetic field strength. With increasing magnetic field strength, the size of proton first increases and then decreases, while the size of neutron always decreases. The present analyse implies that in the core part of the magnetar, the equation of state depend on the magnetic field, which modifies the mass limit of the magnetar.

  19. Study of the neutron field in the vicinity of an unshielded PET cyclotron.

    Science.gov (United States)

    Méndez, R; Iñiguez, M P; Martí-Climent, J M; Peñuelas, I; Vega-Carrillo, H R; Barquero, R

    2005-11-01

    The neutron field in the proximity of an unshielded PET cyclotron was investigated during 18F radioisotope production with an 18 MeV proton beam. Thermoluminescent detector (TLD) models TLD600 and TLD700 as well as Bonner moderating spheres were irradiated at different positions inside the vault room where the cyclotron is located to determine the thermal neutron flux, neutron spectrum and dose equivalent. Furthermore, from a combination of measurements and Monte Carlo simulations the neutron source intensity at the target was estimated. The resulting intensity is in good agreement with the IAEA recommendations. Neutron doses derived from the measured spectra were found to vary between 7 and 320 mSv per 1 microA h of proton-integrated current. Finally, gamma doses were determined from TLD700 readings and amounted to around 10% of the neutron doses.

  20. Simulation of the Mg(Ar) ionization chamber currents by different Monte Carlo codes in benchmark gamma fields

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yi-Chun [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Taiwan (China); Liu, Yuan-Hao, E-mail: yhl.taiwan@gmail.com [Boron Neutron Capture Therapy Center, Nuclear Science and Technology Development Center, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu City 30013, Taiwan (China); Nievaart, Sander [Institute for Energy, Joint Research Centre, European Commission, Petten (Netherlands); Chen, Yen-Fu [Department of Engineering and System Science, National Tsing Hua University, Taiwan (China); Wu, Shu-Wei; Chou, Wen-Tsae [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Taiwan (China); Jiang, Shiang-Huei [Institute of Nuclear Engineering and Science, National Tsing Hua University, Taiwan (China)

    2011-10-01

    High energy photon (over 10 MeV) and neutron beams adopted in radiobiology and radiotherapy always produce mixed neutron/gamma-ray fields. The Mg(Ar) ionization chambers are commonly applied to determine the gamma-ray dose because of its neutron insensitive characteristic. Nowadays, many perturbation corrections for accurate dose estimation and lots of treatment planning systems are based on Monte Carlo technique. The Monte Carlo codes EGSnrc, FLUKA, GEANT4, MCNP5, and MCNPX were used to evaluate energy dependent response functions of the Exradin M2 Mg(Ar) ionization chamber to a parallel photon beam with mono-energies from 20 keV to 20 MeV. For the sake of validation, measurements were carefully performed in well-defined (a) primary M-100 X-ray calibration field, (b) primary {sup 60}Co calibration beam, (c) 6-MV, and (d) 10-MV therapeutic beams in hospital. At energy region below 100 keV, MCNP5 and MCNPX both had lower responses than other codes. For energies above 1 MeV, the MCNP ITS-mode greatly resembled other three codes and the differences were within 5%. Comparing to the measured currents, MCNP5 and MCNPX using ITS-mode had perfect agreement with the {sup 60}Co, and 10-MV beams. But at X-ray energy region, the derivations reached 17%. This work shows us a better insight into the performance of different Monte Carlo codes in photon-electron transport calculation. Regarding the application of the mixed field dosimetry like BNCT, MCNP with ITS-mode is recognized as the most suitable tool by this work.

  1. Simulation of the Mg(Ar) ionization chamber currents by different Monte Carlo codes in benchmark gamma fields

    International Nuclear Information System (INIS)

    High energy photon (over 10 MeV) and neutron beams adopted in radiobiology and radiotherapy always produce mixed neutron/gamma-ray fields. The Mg(Ar) ionization chambers are commonly applied to determine the gamma-ray dose because of its neutron insensitive characteristic. Nowadays, many perturbation corrections for accurate dose estimation and lots of treatment planning systems are based on Monte Carlo technique. The Monte Carlo codes EGSnrc, FLUKA, GEANT4, MCNP5, and MCNPX were used to evaluate energy dependent response functions of the Exradin M2 Mg(Ar) ionization chamber to a parallel photon beam with mono-energies from 20 keV to 20 MeV. For the sake of validation, measurements were carefully performed in well-defined (a) primary M-100 X-ray calibration field, (b) primary 60Co calibration beam, (c) 6-MV, and (d) 10-MV therapeutic beams in hospital. At energy region below 100 keV, MCNP5 and MCNPX both had lower responses than other codes. For energies above 1 MeV, the MCNP ITS-mode greatly resembled other three codes and the differences were within 5%. Comparing to the measured currents, MCNP5 and MCNPX using ITS-mode had perfect agreement with the 60Co, and 10-MV beams. But at X-ray energy region, the derivations reached 17%. This work shows us a better insight into the performance of different Monte Carlo codes in photon-electron transport calculation. Regarding the application of the mixed field dosimetry like BNCT, MCNP with ITS-mode is recognized as the most suitable tool by this work.

  2. Verification and validation benchmarks.

    Energy Technology Data Exchange (ETDEWEB)

    Oberkampf, William Louis; Trucano, Timothy Guy

    2007-02-01

    Verification and validation (V&V) are the primary means to assess the accuracy and reliability of computational simulations. V&V methods and procedures have fundamentally improved the credibility of simulations in several high-consequence fields, such as nuclear reactor safety, underground nuclear waste storage, and nuclear weapon safety. Although the terminology is not uniform across engineering disciplines, code verification deals with assessing the reliability of the software coding, and solution verification deals with assessing the numerical accuracy of the solution to a computational model. Validation addresses the physics modeling accuracy of a computational simulation by comparing the computational results with experimental data. Code verification benchmarks and validation benchmarks have been constructed for a number of years in every field of computational simulation. However, no comprehensive guidelines have been proposed for the construction and use of V&V benchmarks. For example, the field of nuclear reactor safety has not focused on code verification benchmarks, but it has placed great emphasis on developing validation benchmarks. Many of these validation benchmarks are closely related to the operations of actual reactors at near-safety-critical conditions, as opposed to being more fundamental-physics benchmarks. This paper presents recommendations for the effective design and use of code verification benchmarks based on manufactured solutions, classical analytical solutions, and highly accurate numerical solutions. In addition, this paper presents recommendations for the design and use of validation benchmarks, highlighting the careful design of building-block experiments, the estimation of experimental measurement uncertainty for both inputs and outputs to the code, validation metrics, and the role of model calibration in validation. It is argued that the understanding of predictive capability of a computational model is built on the level of

  3. Measurement of Neutron Field Characteristics at Nuclear-Physics Instalations for Personal Radiation Monitoring

    CERN Document Server

    Alekseev, A G; Britvich, G I; Kosyanenko, E V; Pikalov, V A; Gomonov, I P

    2003-01-01

    n this work the observed data of neutron spectra on Rostov NEP, Kursk NEP and Smolensk NEP and on the reactor IRT MIPHI are submitted. For measurement of neutron spectra two types of spectrometer were used: SHANS (IHEP design ) and SDN-MS01 (FEI design). The comparison of the data measurements per-formed by those spectrometers above one-type cells on the reactor RBMK is submitted. On the basis of the 1-st horizontal experimental channel HEC-1 of the IRT reactor 4 reference fields of neutrons are investigated. It is shown, that spectra of neutrons of reference fields can be used for imitation of neutron spectra for conditions of NEP with VVER and RBMK type reactors.

  4. Fundamentals and applications of neutron imaging (applications part 10). Applications of neutron imaging to medical field

    International Nuclear Information System (INIS)

    Described is the application of neutron (Nt) imaging in 3 objects, small animals and excised organs, odontology, and BNCT (boron Nt capture therapy). Nt radiography (NR) uses the fast and thermal Nt. For the former Nt, NR is done by transferring the permeation image on In-leaf to X-ray film or by direct imaging on nitro-cellulose film; and for the latter, by imaging on X-ray film through Gd-converter, by transfer of the image on In- or Dy-leaf to the film or by use of (BaFBr-Gd2O3) Nt imaging plate. NR in animals can image air-containing organs like the lung. For human excised organs, NR can give images of wet tissues in hard organs like malignant tumors in the bone due to a large and small Nt cross sections of H and Ca, respectively. Excised gallstones (cholesterol- and Ca-derived) have been subjected to NR. NR of the pancreatic cancer has been reported with fast Nt. Many studies of NR have been reported in odontology, involving animals', human normal, treated and prosthetic teeth. NR can give information different in nature from X-ray radiography and further development of NR in odontology is expected as one of nondestructive tests. In BNCT-related field, NCAR (NC autoradiography) has been applied for seeing the distribution of 10B in the tumor-bearing mouse given a B compound. Thermal and cold Nts are irradiated on the mouse whole body section and yielded (4He+7Li) radioactivity is detected by CR-39 plastic track detector undergone with various etching treatments. The distribution in the body and tumor can be observed by NCAR and by the recently-developed, versatile high speed image acquisition microscope, respectively. Micro-dosimetry on the CR-39 is thought possible by the latter microscope. (R.T.)

  5. Time-Dependent Neutron and Photon Dose-Field Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Wooten, Hasani Omar [Georgia Inst. of Technology, Atlanta, GA (United States)

    2005-08-01

    A unique tool is developed that allows the user to model physical representations of complicated glovebox facilities in two dimensions and determine neutral-particle flux and ambient dose-equivalent fields throughout that geometry. The Pandemonium code, originally designed to determine flux and dose-rates only, is improved to include realistic glovebox geometries, time-dependent source and detector positions, time-dependent shielding thickness calculations, time-integrated doses, a representative criticality accident scenario based on time-dependent reactor kinetics, and more rigorous photon treatment. A primary benefit of this work has been an extensive analysis and improvement of the photon model that is not limited to the application described in this thesis. The photon model has been extended in energy range to 10 MeV to include photons from fission and new photon buildup factors have been included that account for the effects of photon buildup at slant-path thicknesses as a function of angle, where the mean free path thickness has been preserved. The overall system of codes is user-friendly and it is directly applicable to facilities such as the plutonium facility at Los Alamos National Laboratory, where high-intensity neutron and photon emitters are regularly used. The codes may be used to determine a priori doses for given work scenarios in an effort to supply dose information to process models which will in turn assist decision makers on ensuring as low as reasonably achievable (ALARA) compliance. In addition, coupling the computational results of these tools with the process model visualization tools will help to increase worker safety and radiological safety awareness.

  6. Spin polarization phenomena in dense neutron matter at a strong magnetic field

    CERN Document Server

    Isayev, A A

    2010-01-01

    Spin polarized states in neutron matter at strong magnetic fields up to $10^{18}$ G are considered in the model with the Skyrme effective interaction. Analyzing the self-consistent equations at zero temperature, it is shown that a thermodynamically stable branch of solutions for the spin polarization parameter as a function of density corresponds to the negative spin polarization when the majority of neutron spins are oriented oppositely to the direction of the magnetic field. Besides, it is found that in a strong magnetic field the state with the positive spin polarization can be realized as a metastable state at the high density region in neutron matter. At finite temperature, the entropy of the thermodynamically stable branch demonstrates the unusual behavior being larger than that for the nonpolarized state (at vanishing magnetic field) above certain critical density which is caused by the dependence of the entropy on the effective masses of neutrons in a spin polarized state.

  7. Hall Equilibria: Solutions with toroidal and poloidal magnetic fields in Neutron Star Crusts

    CERN Document Server

    Gourgouliatos, K N; Lyutikov, M; Reisenegger, A

    2013-01-01

    We present Hall equilibrium solutions for neutron stars crusts containing toroidal and poloidal magnetic field. Some simple cases are solved analytically while more complicated configurations are found numerically through a Gauss-Seidel elliptic partial differential equation solver.

  8. A unique focusing property of a parabolic mirror for neutrons in the gravitational field: geometric proof

    OpenAIRE

    Masalovich, S.

    2014-01-01

    An extraordinary focusing property of a parabolic mirror for ultracold neutrons in the presence of the gravitational field was first reported by A. Steyerl and co-authors. It was shown that all neutrons emitted from the focus of the mirror will be reflected back upon the same focus point passing, in between, a point of return in the gravitational field. The present note offers a complementary geometric proof of this feature and discusses some implications.

  9. Atomic parity nonconservation, neutron radii, and effective field theories of nuclei

    OpenAIRE

    Sil, Tapas; Centelles Aixalà, Mario; Viñas Gausí, Xavier; Piekarewicz, J.

    2005-01-01

    Accurately calibrated effective field theories are used to compute atomic parity non-conserving (APNC) observables. Although accurately calibrated, these effective field theories predict a large spread in the neutron skin of heavy nuclei. While the neutron skin is strongly correlated to a large number of physical observables, in this contribution we focus on its impact on new physics through APNC observables. The addition of an isoscalar-isovector coupling constant to the effective Lagrangian...

  10. Spin Precession of Slow Neutrons in Einstein-Cartan Gravity with Torsion, Chameleon and Magnetic Field

    CERN Document Server

    Ivanov, A N

    2016-01-01

    We analyse a spin precession of slow neutrons in the Einstein-Cartan gravity with torsion, chameleon and magnetic field. For the derivation of the Heisenberg equation of motion of the neutron spin we use the effective low-energy potential, derived by Ivanov and Wellenzohn (Phys. Rev. D92, 125004 (2015)) for slow neutrons, coupled to gravitational, chameleon and torsion fields to order 1/m, where m is the neutron mass. In addition to this low-energy interactions we switch on the interaction of slow neutrons with a magnetic field. We show that to linear order approximation with respect to gravitational, chameleon and torsion fields the Dirac Hamilton operator for fermions (neutrons), moving in spacetimes created by rotating coordinate systems, contains the anti-Hermitian operators of torsion-fermion (neutron) interactions, caused by torsion scalar and tensor degrees of freedom. Such anti-Hermitian operators violate CP and T invariance. One may assume that in the rotating Universe and galaxies the obtained anti-...

  11. Analysis of unstable chromosome alterations frequency induced by neutron-gamma mixed field radiation

    International Nuclear Information System (INIS)

    Nowadays monitoring chromosome alterations in peripheral blood lymphocytes have been used to access the radiation absorbed dose in individuals exposed accidental or occupationally to gamma radiation. However there are not many studies based on the effects of mixed field neutron-gamma. The radiobiology of neutrons has great importance because in nuclear factories worldwide there are several hundred thousand individuals monitored as potentially receiving doses of neutron. In this paper it was observed the frequencies of unstable chromosome alterations induced by a gamma-neutron mixed field. Blood was obtained from one healthy donor and exposed to mixed field neutron-gamma sources 241AmBe (20 Ci) at the Neutron Calibration Laboratory (NCL-CRCN/NE-PE-Brazil). The chromosomes were observed at metaphase, following colcemid accumulation and 1000 well-spread metaphases were analyzed for the presence of chromosome alterations by two experienced scorers. The results suggest that there is the possibility of a directly proportional relationship between absorbed dose of neutron-gamma mixed field radiation and the frequency of unstable chromosome alterations analyzed in this paper. (author)

  12. Atmospheres and radiating surfaces of neutron stars with strong magnetic fields

    CERN Document Server

    Potekhin, A Y; Chabrier, G

    2016-01-01

    We review the current status of the theory of thermal emission from the surface layers of neutron stars with strong magnetic fields $B\\sim 10^{10}-10^{15}$ G, including formation of the spectrum in a partially ionized atmosphere and at a condensed surface. In particular, we describe recent progress in modeling partially ionized atmospheres of central compact objects in supernova remnants, which may have moderately strong fields $B\\sim 10^{10}-10^{11}$ G. Special attention is given to polarization of thermal radiation emitted by a neutron star surface. Finally, we briefly describe applications of the theory to observations of thermally emitting isolated neutron stars.

  13. The optimization study of Bonner sphere in the epi-thermal neutron irradiation field for BNCT.

    Science.gov (United States)

    Ueda, H; Tanaka, H; Maruhashi, A; Ono, K; Sakurai, Y

    2011-12-01

    The optimization study on the Bonner sphere in the epi-thermal neutron irradiation field for BNCT was done for the moderator material, moderator size, and activation foils as a neutron detector in the sphere. The saturated activity for the activation foil was obtained from the calculated response, and the effective energy range for each Bonner sphere was determined from the saturated activity. We can see that boric acid solution moderator is suitable for the spectrum measurement of a epi-thermal neutron irradiation field.

  14. Development of a compact neutron source based on field ionization processes

    Energy Technology Data Exchange (ETDEWEB)

    Persaud, Arun; Allen, Ian; Dickinson, Michael R.; Schenkel, Thomas; Kapadia, Rehan; Takei, Kuniharu; Javey, Ali

    2010-11-25

    The authors report on the use of carbon nanofiber nanoemitters to ionize deuterium atoms for the generation of neutrons in a deuterium-deuterium reaction in a preloaded target. Acceleration voltages in the range of 50-80 kV are used. Field emission of electrons is investigated to characterize the emitters. The experimental setup and sample preparation are described and first data of neutron production are presented. Ongoing experiments to increase neutron production yields by optimizing the field emitter geometry and surface conditions are discussed.

  15. Development of a Compact Neutron Source based on Field Ionization Processes

    CERN Document Server

    Persaud, Arun; Dickinson, Michael R; Kapadia, Rehan; Takei, Kuniharu; Javey, Ali; Schenkel, Thomas

    2010-01-01

    We report on the use of nano-emitters, here carbon nano-fibers(CNFs), to ionize deuterium atoms and the creation of neutrons in a deuterium-deuterium reaction in a pre-loaded target. Acceleration voltages in the range of 50-80 kV are used. Field emission of electrons is investigated to characterize the emitters. Experimental setup and sample preparation are discussed and preliminary data of first neutron production is shown. We further discuss ongoing experiments to increase neutron production yields by optimizing the field emitter geometry and surface conditions.

  16. Determination of cross sections for the production of low-energy monoenergetic neutron fields

    International Nuclear Information System (INIS)

    The response of a neutron detector, defined as the reading of the device per unit of incident fluence or dose, varies with neutron energy. The experimental determination of this variation, i.e. of the response function of this instrument, has to be performed by facilities producing monoenergetic neutron fields. These neutrons are commonly produced by interaction between accelerated ions (proton or deuteron) onto a thin target composed of a reactive layer deposited on a metallic backing. Using the 7Li(p, n), 3H(p, n), 2H(d, n) and 3H(d, n) reactions, monoenergetic neutrons are obtained between 120 keV and 20 MeV in the ion beam direction (0 deg.). To reach lower neutron energies, the angle of the measuring point with respect to the ion beam direction can be increased. However, this method presents several problems of neutron energy and fluence homogeneities over the detector surface, as well as an important increase of the scattered neutron contribution. Another solution is to investigate other nuclear reactions, as 45Sc(p, n) allowing to extend the neutron energy range down to 8 keV at 0 deg.. A complete study of this reaction and its cross section has been undertaken within the framework of a scientific cooperation between the laboratory of neutron metrology and dosimetry (IRSN, France), two European national metrological institutes, the National Physical Laboratory (UK) and the Physikalisch-Technische Bundesanstalt (Germany), and IRMM, the Institute for Reference Materials and Measurements (EC). In parallel, other possible reactions have been investigated: 65Cu(p, n), 51V(p, n), 57Fe(p, n), 49Ti(p, n), 53Cr(p, n) and 37Cl(p, n). They were compared in terms of neutron fluence and minimum energy of the produced neutrons. (author)

  17. Response of a lithium gadolinium borate scintillator in monoenergetic neutron fields.

    Science.gov (United States)

    Williams, A M; Beeley, P A; Spyrou, N M

    2004-01-01

    Accurate estimation of neutron dose requires knowledge of the neutron energy distribution in the working environment. Existing neutron spectrometry systems, Bonner spheres for example, are large and bulky, and require long data acquisition times. A portable system that could indicate the approximate neutron energy spectrum in a short time would be extremely useful in radiation protection. A composite scintillator, consisting of lithium gadolinium borate crystals in a plastic scintillator matrix, produced by Photogenics is being tested for this purpose. A prototype device based on this scintillator and digital pulse processing electronics has been calibrated using quasi-monoenergetic neutron fields at the low-scatter facility of the UK National Physical Laboratory (NPL). Energies selected were 144, 250, 565, 1400, 2500 and 5000 keV, with correction for scattered neutrons being made using the shadow cone technique. Measurements were also made in the NPL thermal neutron field. Pulse distributions collected with the digitiser in capture-gated mode are presented, and detection efficiency and energy resolution derived. For comparison, neutron spectra were also collected using the commercially available Microspec N-Probe from Bubble Technology Industries, which consists of an NE213 scintillator and a 3He proportional counter.

  18. Estimating field scale root zone soil moisture using the cosmic-ray neutron probe

    Science.gov (United States)

    Peterson, A. M.; Helgason, W. D.; Ireson, A. M.

    2015-12-01

    Many practical hydrological, meteorological and agricultural management problems require estimates of soil moisture with an areal footprint equivalent to "field scale", integrated over the entire root zone. The cosmic-ray neutron probe is a promising instrument to provide field scale areal coverage, but these observations are shallow and require depth scaling in order to be considered representative of the entire root zone. A study to identify appropriate depth-scaling techniques was conducted at a grazing pasture site in central Saskatchewan, Canada over a two year period. Area-averaged soil moisture was assessed using a cosmic-ray neutron probe. Root zone soil moisture was measured at 21 locations within the 5002 m2 area, using a down-hole neutron probe. The cosmic-ray neutron probe was found to provide accurate estimates of field scale surface soil moisture, but accounted for less than 40 % of the seasonal change in root zone storage due to its shallow measurement depth. The root zone estimation methods evaluated were: (1) the coupling of the cosmic-ray neutron probe with a time stable neutron probe monitoring location, (2) coupling the cosmic-ray neutron probe with a representative landscape unit monitoring approach, and (3) convolution of the cosmic-ray neutron probe measurements with the exponential filter. The time stability method provided the best estimate of root zone soil moisture (RMSE = 0.004 cm3 cm-3), followed by the exponential filter (RMSE = 0.012 cm3 cm-3). The landscape unit approach, which required no calibration, had a negative bias but estimated the cumulative change in storage reasonably. The feasibility of applying these methods to field sites without existing instrumentation is discussed. It is concluded that the exponential filter method has the most potential for estimating root zone soil moisture from cosmic-ray neutron probe data.

  19. Estimating field-scale root zone soil moisture using the cosmic-ray neutron probe

    Science.gov (United States)

    Peterson, Amber M.; Helgason, Warren D.; Ireson, Andrew M.

    2016-04-01

    Many practical hydrological, meteorological, and agricultural management problems require estimates of soil moisture with an areal footprint equivalent to field scale, integrated over the entire root zone. The cosmic-ray neutron probe is a promising instrument to provide field-scale areal coverage, but these observations are shallow and require depth-scaling in order to be considered representative of the entire root zone. A study to identify appropriate depth-scaling techniques was conducted at a grazing pasture site in central Saskatchewan, Canada over a 2-year period. Area-averaged soil moisture was assessed using a cosmic-ray neutron probe. Root zone soil moisture was measured at 21 locations within the 500 m × 500 m study area, using a down-hole neutron probe. The cosmic-ray neutron probe was found to provide accurate estimates of field-scale surface soil moisture, but measurements represented less than 40 % of the seasonal change in root zone storage due to its shallow measurement depth. The root zone estimation methods evaluated were: (a) the coupling of the cosmic-ray neutron probe with a time-stable neutron probe monitoring location, (b) coupling the cosmic-ray neutron probe with a representative landscape unit monitoring approach, and (c) convolution of the cosmic-ray neutron probe measurements with the exponential filter. The time stability method provided the best estimate of root zone soil moisture (RMSE = 0.005 cm3 cm-3), followed by the exponential filter (RMSE = 0.014 cm3 cm-3). The landscape unit approach, which required no calibration, had a negative bias but estimated the cumulative change in storage reasonably. The feasibility of applying these methods to field sites without existing instrumentation is discussed. Based upon its observed performance and its minimal data requirements, it is concluded that the exponential filter method has the most potential for estimating root zone soil moisture from cosmic-ray neutron probe data.

  20. Benchmark selection

    DEFF Research Database (Denmark)

    Hougaard, Jens Leth; Tvede, Mich

    2002-01-01

    Within a production theoretic framework, this paper considers an axiomatic approach to benchmark selection. It is shown that two simple and weak axioms; efficiency and comprehensive monotonicity characterize a natural family of benchmarks which typically becomes unique. Further axioms are added...

  1. Interactive benchmarking

    DEFF Research Database (Denmark)

    Lawson, Lartey; Nielsen, Kurt

    2005-01-01

    We discuss individual learning by interactive benchmarking using stochastic frontier models. The interactions allow the user to tailor the performance evaluation to preferences and explore alternative improvement strategies by selecting and searching the different frontiers using directional...... in the suggested benchmarking tool. The study investigates how different characteristics on dairy farms influences the technical efficiency....

  2. Effects of neutrino emissivity on the cooling of neutron stars in the presence of a strong magnetic field

    Science.gov (United States)

    Coelho, Eduardo Lenho; Chiapparini, Marcelo; Negreiros, Rodrigo Picanço

    2015-12-01

    One of the most interesting kind of neutron stars are the pulsars, which are highly magnetized neutron stars with fields up to 1014 G at the surface. The strength of magnetic field in the center of a neutron star remains unknown. According to the scalar virial theorem, magnetic field in the core could be as large as 1018 G. In this work we study the influence of strong magnetic fields on the cooling of neutron stars coming from direct Urca process. Direct Urca process is an extremely efficient mechanism for cooling a neutron star after its formation. The matter is described using a relativistic mean-field model at zero temperature with eight baryons (baryon octet), electrons and muons. We obtain the relative population of each species of particles as function of baryon density for different magnetic fields. We calculate numerically the cooling of neutron stars for a parametrized magnetic field and compare the results for the case without a magnetic field.

  3. Describing one- and two-neutron halos in effective field theory

    Indian Academy of Sciences (India)

    Daniel R Phillips

    2014-11-01

    In this paper, the recent work our group has undertaken on effective field theory (EFT) analyses of experimental data pertaining to one- and two-neutron halo nuclei is discussed. The cases of 19C and 8Li (one-neutron halos) and 22C (two-neutron halo) are considered. For 19C and 8Li electromagnetic processes, such as Coulomb dissociation and radiative capture are considered. In the 22C system the way in which the measured matter radius can be used to derive constraints on the two-neutron separation energy of this very neutron-rich system is shown. In each case the Halo EFT’s ability to correlate different experimental observables with one another, in a modelindependent manner, and up to an accuracy that is determined by the separation of scales in the halo system is shown.

  4. Thermoluminescence dosimetry of a thermal neutron field and comparison with Monte Carlo calculations.

    Science.gov (United States)

    Fernandes, A C; Santos, J P; Kling, A; Marques, J G; Gonçalves, I C; Carvalho, A Ferro; Santos, L; Cardoso, J; Osvay, M

    2004-01-01

    The characteristics of thermoluminescence dosemeters (TLDs) regarding the determination of photon and neutron absorbed doses were investigated in a thermal neutron beam. Harshaw TLD-100 (LiF:Mg,Ti) and TLD-700 (7LiF:Mg,Ti) were compared with similar materials from Solid Dosimetric Detector and Method Laboratory (People's Republic of China). Harshaw TLD-700H (7LiF:Mg,Cu,P) and aluminium oxide (Al2O3:Mg,Y) from Hungary were also considered for photon dose measurement. The neutron sensitivity of the investigated materials was measured and found to be consistent with values reported by other authors. A comparison was made between the TL dose measurements and results obtained via conventional methods. An agreement within 20% was obtained, which demonstrates the ability of TLD for measuring neutron and photon doses in a mixed field, using careful calibration procedures and determining the neutron sensitivity for the usage conditions. PMID:15367765

  5. Monte Carlo simulation of MLC-shaped TrueBeam electron fields benchmarked against measurement

    CERN Document Server

    Lloyd, Samantha AM; Zavgorodni, Sergei

    2014-01-01

    Modulated electron radiotherapy (MERT) and combined, modulated photon/electron radiotherapy (MPERT) have received increased research attention, having shown capacity for reduced low dose exposure to healthy tissue and comparable, if not improved, target coverage for a number of treatment sites. Accurate dose calculation tools are necessary for clinical treatment planning, and Monte Carlo (MC) is the gold standard for electron field simulation. With many clinics replacing older accelerators, MC source models of the new machines are needed for continued development, however, Varian has kept internal schematics of the TrueBeam confidential and electron phase-space sources have not been made available. TrueBeam electron fields are not substantially different from those generated by the Clinac 21EX, so we have modified the internal schematics of the Clinac 21EX to simulate TrueBeam electrons. BEAMnrc/DOSXYZnrc were used to simulate 5x5 and 20x20 cm$^2$ electron fields with MLC-shaped apertures. Secondary collimati...

  6. Benchmarking the Performance of Mobile Laser Scanning Systems Using a Permanent Test Field

    Directory of Open Access Journals (Sweden)

    Hannu Hyyppä

    2012-09-01

    Full Text Available The performance of various mobile laser scanning systems was tested on an established urban test field. The test was connected to the European Spatial Data Research (EuroSDR project “Mobile Mapping—Road Environment Mapping Using Mobile Laser Scanning”. Several commercial and research systems collected laser point cloud data on the same test field. The system comparisons focused on planimetric and elevation errors using a filtered digital elevation model, poles, and building corners as the reference objects. The results revealed the high quality of the point clouds generated by all of the tested systems under good GNSS conditions. With all professional systems properly calibrated, the elevation accuracy was better than 3.5 cm up to a range of 35 m. The best system achieved a planimetric accuracy of 2.5 cm over a range of 45 m. The planimetric errors increased as a function of range, but moderately so if the system was properly calibrated. The main focus on mobile laser scanning development in the near future should be on the improvement of the trajectory solution, especially under non-ideal conditions, using both improvements in hardware and software. Test fields are relatively easy to implement in built environments and they are feasible for verifying and comparing the performance of different systems and also for improving system calibration to achieve optimum quality.

  7. Time analysis of the slow neutron field generated by the accelerating tube downhole

    International Nuclear Information System (INIS)

    Pulsed neutron logging (PNL) consists in the irradiation of rocks around the well by a pulsed periodic flux of fast neutrons generated by a portable accelerating tube and detection of thermal neutrons during pauses between the neutron pulses. The main aim of the PNL is determining the time distribution of thermal neutrons in the well and formation. At present the PNL response is considered as the sum of two exponentially decaying components, one related to the well and another one - to rock formation: J(t) = A1 exp (-λ1t) + A2 exp (-λ2t) . This is a result of homogenization of a neutron field in the borehole and formation space which is characterized by complicated radial structure and heterogeneous neutron properties. The time base of measurements T is subdivided into a set consisting of I narrow time windows Δt and the PNL response is formed as the series of neutron registration events Ni for each time window Δt with number i =1 to I (time neutron spectrum). Presented is a noise-immune algorithm for decomposition of the experimental time neutron spectrum into two components using the following overdetermined system of equations: Ni - Δt (λ1 + λ2) Σk=i Nk + (Δt)2 λ1λ2 Σk=i Σj=k Nj + [T - (i - 1) Δt][J'(T) - (λ1 + λ2) J(T)]Δt - J(T) Δt 0. Two amplitudes and two time decay constants of these components give an information about the neutron absorption cross-section and porosity of rocks. Presented are physical characteristics of new Russian PNL tools and examples illustrating the processing of PNL in oil wells. (author)

  8. Performance of a PADC personal neutron dosemeter at simulated and real workplace fields of the nuclear industry

    International Nuclear Information System (INIS)

    In the framework of the EVIDOS (Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields) project, funded by the EC, measurements with PADC personal neutron dosemeters were carried out at several workplace fields of the nuclear industry and at simulated workplace fields. The measured personal neutron dose equivalents of the PADC personal neutron dosemeter are compared with values that were assessed within the EVIDOS project by other partners. The detection limits for different spectra types are given. In cases were the neutron dose was too low to be measured by the PADC personal neutron dosemeter, the response is estimated by convoluting the responses to monoenergetic neutrons with the dose energy distribution measured within EVIDOS. The advantages and limitations of the PADC personal neutron dosemeter are discussed. (authors)

  9. Magnetic field and EoS of neutron star matter at finite temperature

    International Nuclear Information System (INIS)

    In this paper, magnetic field and equation of state (EoS) of neutron star matter are studied under relativistic mean field theory. A nonzero mass term of magnetic field in the Lagrangian is introduced, which depends on baryon density of charged particles. The magnetic field has not been treated as external as usual and the calculations of magnetic field strength at finite temperature reveal the existence of inflection points in certain densities. (author)

  10. Relativistic theory of inverse beta-decay of polarized neutron in strong magnetic field

    Indian Academy of Sciences (India)

    S Shinkevich; A Studenikin

    2005-08-01

    The relativistic theory of the inverse beta-decay of polarized neutron, + → + -, in strong magnetic field is developed. For the proton wave function we use the exact solution of the Dirac equation in the magnetic filed that enables us to account exactly for effects of the proton momentum quantization in the magnetic field and also for the proton recoil motion. The effect of nucleons anomalous magnetic moments in strong magnetic fields is also discussed. We examine the cross-section for different energies and directions of propagation of the initial neutrino accounting for neutron polarization. It is shown that in the super-strong magnetic field the totally polarized neutron matter is transparent for neutrinos propagating antiparallel to the direction of polarization. The developed relativistic approach can be used for calculations of cross-sections of the other URCA processes in strong magnetic fields.

  11. Spin precession of slow neutrons in Einstein-Cartan gravity with torsion, chameleon, and magnetic field

    Science.gov (United States)

    Ivanov, A. N.; Wellenzohn, M.

    2016-02-01

    We analyze a spin precession of slow neutrons in the Einstein-Cartan gravity with torsion, chameleon and magnetic field. For the derivation of the Heisenberg equation of motion of the neutron spin we use the effective low-energy potential, derived by Ivanov and Wellenzohn [Phys. Rev. D 92, 125004 (2015)] for slow neutrons, coupled to gravitational, chameleon, and torsion fields to order 1 /m , where m is the neutron mass. In addition to these low-energy interactions we switch on the interaction of slow neutrons with a magnetic field. We show that to linear order approximation with respect to gravitational, chameleon, and torsion fields the Dirac Hamilton operator for fermions (neutrons), moving in spacetimes created by rotating coordinate systems, contains the anti-Hermitian operators of torsion-fermion (neutron) interactions, caused by torsion scalar and tensor space-space-time and time-space-space degrees of freedom. Such anti-Hermitian operators violate C P and T invariance. In the low-energy approximation the C P and T violating torsion-fermion (neutron) interactions appear only to order O (1 /m ). One may assume that in the rotating Universe and galaxies the obtained anti-Hermitian torsion-fermion interactions might be an origin of (i) violation of C P and T invariance in the Universe and (ii) of baryon asymmetry. We show that anti-Hermitian torsion-fermion interactions of relativistic fermions, violating C P and T invariance, (i) cannot be removed by nonunitary transformations of the Dirac fermion wave functions and (ii) are conformal invariant. According to general requirements of conformal invariance of massive particle theories in gravitational fields [see R. H. Dicke, Phys. Rev. 125, 2163 (1962) and A. J. Silenko, Phys. Rev. D 91, 065012 (2015)], conformal invariance of anti-Hermitian torsion-fermion interactions is valid only if the fermion mass is changed by a conformal factor.

  12. The measurement of chemical persistence in the field by benchmarking : Theory and Experiment

    OpenAIRE

    Zou, Hongyan

    2015-01-01

    Persistence is one of the core criteria in chemical exposure and hazard assessment. It is often defined as the half-life for the removal of a chemical from a specified environment by transformation. Chemicals with long transformation half-lives may pose high risks for wildlife or humans and be subject to long-range transport to remote areas. It is challenging to measure persistence directly in the field in view of the complexity of the natural environment and spatial and temporal variability ...

  13. Characteristics of the simulated workplace neutron fields using a 252Cf source surrounded with cylindrical moderators

    International Nuclear Information System (INIS)

    The authors established the simulated workplace neutron fields using a 252Cf source surrounded with cylindrical moderators at the Japan Nuclear Cycle Development Inst. (JNC), Tokai Works. The moderators are annular cylinders made of polymethyl methacrylate and steel. The neutron energy spectrum at the reference calibration point was evaluated from the calculations by MCNP-4B and the measurements by the Bonner multisphere spectrometer and the hydrogen-filled proportional counters. The calculated neutron spectra were in good agreements with the measured ones. These fields can provide the realistic neutron spectra similar to those encountered around the glove-boxes of the fabrication process of MOX (PuO2-UO2 mixed oxide) fuel. (authors)

  14. Nuclei, hypernuclei, and neutron stars in a relativistic mean-field model

    International Nuclear Information System (INIS)

    An essential aim of this thesis consisted in the obtainment of an optimal description of finite also strangeness carrying nuclei in the framework of a relativistic mean-field model. For this the model parameters were fitted to experimental nuclear and hypernuclear data. By the so optimized parametrizations the - among others - equations of state of neutron matter were extrapolated and by solving of the Oppenheimer-Volkoff equation neutron star properties calculated. In this connection also the possible existence of a quark phase in the interior of neutron stars was considered. (orig.)

  15. Gravitationally enhanced depolarization of ultracold neutrons in magnetic-field gradients

    Science.gov (United States)

    Harris, P. G.; Pendlebury, J. M.; Devenish, N. E.

    2014-01-01

    Trapped ultracold neutrons (UCNs) have for many years been the mainstay of experiments to search for the electric dipole moment (EDM) of the neutron, a critical parameter in constraining scenarios of new physics beyond the Standard Model. Because their energies are so low, UCNs preferentially populate the lower region of their physical enclosure and do not sample uniformly the ambient magnetic field throughout the storage volume. This leads to a substantial increase in the rate of depolarization, as well as to shifts in the measured frequency of the stored neutrons. Consequences for EDM measurements are discussed.

  16. Optimization of a single sphere albedo system using 3He counters for the measurement of neutron dose equivalent rates and the field calibration of personnel albedo neutron dosimeters

    International Nuclear Information System (INIS)

    The laboratory type of an active single sphere albedo dosemeter system using three 3He proportional counters in a polyethylene sphere for the measurement of neutron dose equivalent rates and the field calibration of personnel neutron dosemeters was optimized with respect to the detector-moderator combination by means of calibration exposures. One detector is located in the centre of the sphere to measure the neutron dose equivalent rate and the other two detectors near the moderator surface, in order to simulate the response of the albedo neutron detector and the thermal neutron detector. The response of the detectors to neutrons in the range between thermal and 14 MeV neutrons was investigated for various moderator-absorber combinations. Comparison was made between the system response and the response of the passive detector system. After completion the active system could be used for comprehensive neutron field measurements in radiation protection. By means of a microprocessor the linear combination of the three detector readings gives energy independent readings of the neutron dose equivalent rate, the absorbed dose rate and the neutron flux density at particle accelerators and nuclear facilities. (orig./HP)

  17. Gravitationally enhanced depolarization of ultracold neutrons in magnetic-field gradients

    OpenAIRE

    Harris, P.G.; Pendlebury, J.M.; Devenish, N. E.

    2014-01-01

    Trapped ultracold neutrons (UCN) have for many years been the mainstay of experiments to search for the electric dipole moment (EDM) of the neutron, a critical parameter in constraining scenarios of new physics beyond the Standard Model. Because their energies are so low, UCN preferentially populate the lower region of their physical enclosure, and do not sample uniformly the ambient magnetic field throughout the storage volume. This leads to a substantial increase in the rate of depolariza...

  18. 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

  19. Demonstration of a white beam far-field neutron interferometer for spatially resolved small angle neutron scattering

    CERN Document Server

    Hussey, Daniel S; Yuan, Guangcui; Pushin, Dmitry; Sarenac, Dusan; Huber, Michael G; Jacobson, David L; LaManna, Jacob M; Wen, Han

    2016-01-01

    We provide the first demonstration that a neutron far-field interferometer can be employed to measure the microstructure of a sample. The interferometer is based on the moir\\'e pattern of two phase modulating gratings which was previously realized in hard x-ray and visible light experiments. The autocorrelation length of this interferometer, and hence the microstructure length scale that is probed, is proportional to the grating spacing and the neutron wavelength, and can be varied over several orders of magnitude for one pair of gratings. We compare our measurements of the change in visibility from monodisperse samples with calculations which show reasonable agreement. The potential advantages of a far-field neutron interferometer include high fringe visibility in a polychromatic beam (over 30 %), no requirement for an absorbing grating to resolve the interference fringes, and the ability to measure the microstructure in the length scale range of 100 nm to 10 \\mum by varying either the grating spacing or neu...

  20. Semiconductor High-Level Dosimeters Used in the SLAC Mixed Gamma and Neutron Fields

    CERN Document Server

    Mao, S

    2003-01-01

    As part of an exploration of Semiconductor High-Level Dosimetry (SHLD) in the accelerator radiation fields, the response of SHLD system, composed of dual MOSFETs, wide-base PIN diode, and a microprocessor-controlled reader, was calibrated in photon (Co-60) and neutron (Bare-reactor) fields. The response curves for the MOSFET and the PIN diode were determined. The neutron sensitivity of the PIN diode is about a factor of 2200 times higher than its photon sensitivity. Therefore, the PIN diode can be used to measure the neutron dose and virtually ignore the photon dose contribution. The MOSFET can be used to estimate the photon dose after subtracting the ionizing effect of the neutrons. The SHLD was used in the SLAC mixed field to measure the photon and neutron doses around a copper beam dump. The photon measurements near the copper dump agreed reasonably with the FLUKA Monte Carlo calculations. The neutron measurements agreed with FLUKA calculations to within a factor of two.

  1. Are neutron stars crushed? Gravitomagnetic tidal fields as a mechanism for binary-induced collapse

    CERN Document Server

    Favata, M

    2005-01-01

    (abridged) Numerical simulations of binary neutron stars by Wilson, Mathews, and Marronetti indicated that neutron stars that are stable in isolation can be made to collapse to black holes when placed in a binary. This claim was surprising as it ran counter to the Newtonian expectation that a neutron star in a binary should be more stable, not less. After correcting an error found by Flanagan, Wilson and Mathews found that the compression of the neutron stars was significantly reduced but not eliminated. This has motivated us to ask the following general question: Under what circumstances can general relativistic tidal interactions cause an otherwise stable neutron star to be compressed? We have found that if a non-rotating neutron star possess a current quadrupole moment, interactions with a gravitomagnetic tidal field can lead to a compressive force on the star. If this current quadrupole is induced by the gravitomagnetic tidal field, it is related to the tidal field by an equation-of-state-dependent consta...

  2. Structure detection in the D1 CFHTLS deep field using accurate photometric redshifts: a benchmark

    CERN Document Server

    Mazure, A; Pierre, M; Lefèvre, O; Arnouts, S; Duc, P A; Ilbert, O; Le Brun, V; Meneux, B; Pacaud, F; Surdej, J; Valtchanov, I

    2007-01-01

    We investigate structures in the D1 CFHTLS deep field in order to test the method that will be applied to generate homogeneous samples of clusters and groups of galaxies in order to constrain cosmology and detailed physics of groups and clusters. Adaptive kernel technique is applied on galaxy catalogues. This technique needs none of the usual a-priori assumptions (luminosity function, density profile, colour of galaxies) made with other methods. Its main drawback (decrease of efficiency with increasing background) is overcame by the use of narrow slices in photometric redshift space. There are two main concerns in structure detection. One is false detection and the second, the evaluation of the selection function in particular if one wants "complete" samples. We deal here with the first concern using random distributions. For the second, comparison with detailed simulations is foreseen but we use here a pragmatic approach with comparing our results to GalICS simulations to check that our detection number is n...

  3. LiCaAlF6 scintillators in neutron and gamma radiation fields

    Science.gov (United States)

    Viererbl, L.; Klupák, V.; Vinš, M.; Koleška, M.; Šoltés, J.; Yoshikawa, A.; Nikl, M.

    2016-09-01

    Intentionally doped LiCaAlF6 (LiCAF) single crystals are prospective scintillators, especially for thermal neutron detection through the 6Li(n,t)4He nuclear reaction. Four different LiCAF scintillator samples were tested in various neutron and gamma fields. Two of the tested samples were LiCAF:Eu and LiCAF:Eu,Na single crystals, and another two samples were made of LiCAF:Eu micro crystals dispersed in transparent rubber, with different rubber dimensions. All LiCAF samples contain lithium enriched to6Li. A plutonium-beryllium source was used as a neutron source. The neutron spectrum was modified by moderator and filter to get different ratios between thermal, epithermal and fast neutron fluence rates. The MCNP code was used for calculations of the fluence rates for different configurations. Radionuclides 137Cs and 60Co were applied as gamma radiation sources. The light signal from the scintillator was evaluated with a photomultiplier and a multichannel analyzer. The purpose of this work was to study the characteristics of LiCAF scintillators, especially the ability to discriminate signals from neutron and gamma radiation, which is the basic scintillator condition for neutron detection in mixed neutron-gamma radiation fields. Generally, the discrimination can be done by the pulse height and/or the pulse shape of the evaluated signals. Both methods can be used for a LiCAF scintillator. However, only the pulse height discrimination method is discussed in this paper. The possibility of fast neutron detection with LiCAF scintillators was also tested.

  4. Magnetic Field Effect on β+ Decay in the Crusts of Accreting Neutron Stars

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jie; LIU Men-Quan; LUO Zhi-Quan

    2007-01-01

    Based on shell model of nuclei,the influence of a high magnetic field on ββ+ decay in the crusts of accreting neutron stars is analyzed.The magnetic field effect on 54Mn is discussed.The results show that a weak magnetic field makes little effect on β+ decay but a strong magnetic field (B > 1011 G) improves β+ decay rates obviously.The conclusion derived will benefit to develop further research on nuclear astrophysics in the future.

  5. Maxwell equation violation by density dependent magnetic fields in neutron stars

    CERN Document Server

    Menezes, Débora P

    2016-01-01

    We show that the widely used density dependent magnetic field prescriptions, necessary to account for the variation of the field intensity from the crust to the core of neutron stars violate one of the Maxwell equations. We estimate how strong the violation is when different equations of state are used and check for which cases the pathological problem can be cured.

  6. A prototype vector magnetic field monitoring system for a neutron electric dipole moment experiment

    CERN Document Server

    Nouri, N; Brown, M A; Carr, R; Filippone, B; Osthelder, C; Plaster, B; Slutsky, S; Swank, C

    2015-01-01

    We present results from a first demonstration of a magnetic field monitoring system for a neutron electric dipole moment experiment. The system is designed to reconstruct the vector components of the magnetic field in the interior measurement region solely from exterior measurements.

  7. A comprehensive spectrometry study of a stray neutron radiation field in scanning proton therapy

    Science.gov (United States)

    Mares, Vladimir; Romero-Expósito, Maite; Farah, Jad; Trinkl, Sebastian; Domingo, Carles; Dommert, Martin; Stolarczyk, Liliana; Van Ryckeghem, Laurent; Wielunski, Marek; Olko, Pawel; Harrison, Roger M.

    2016-06-01

    The purpose of this study is to characterize the stray neutron radiation field in scanning proton therapy considering a pediatric anthropomorphic phantom and a clinically-relevant beam condition. Using two extended-range Bonner sphere spectrometry systems (ERBSS), Working Group 9 of the European Radiation Dosimetry Group measured neutron spectra at ten different positions around a pediatric anthropomorphic phantom irradiated for a brain tumor with a scanning proton beam. This study compares the different systems and unfolding codes as well as neutron spectra measured in similar conditions around a water tank phantom. The ten spectra measured with two ERBSS systems show a generally similar thermal component regardless of the position around the phantom while high energy neutrons (above 20 MeV) were only registered at positions near the beam axis (at 0°, 329° and 355°). Neutron spectra, fluence and ambient dose equivalent, H *(10), values of both systems were in good agreement (patients. The ten measured spectra provide precise information about the exposure of healthy organs to thermal, epithermal, evaporation and intra-nuclear cascade neutrons. This comprehensive spectrometry analysis can also help in understanding the tremendous literature data based rem-counters while also being of great value for general neutron shielding and radiation safety studies.

  8. Miniature neutron sources: Thermal neutron sources and their uses in the academic field

    International Nuclear Information System (INIS)

    The three levels of thermal neutron sources are introduced: university laboratory sources; infrastructure sources; and world-class sources; and the needs for each kind and their inter-dependence will be emphasized. A description of the possibilities for university sources based on α-Be reactions or spontaneous fission emission is given, and current experience with them is described. A new generation of infrastructure sources is needed to continue the regional programs based on small reactors. Some possibilities for accelerator sources that could meet this need are considered

  9. Simultaneous and integrated neutron-based techniques for material analysis of a metallic ancient flute

    Science.gov (United States)

    Festa, G.; Pietropaolo, A.; Grazzi, F.; Sutton, L. F.; Scherillo, A.; Bognetti, L.; Bini, A.; Barzagli, E.; Schooneveld, E.; Andreani, C.

    2013-09-01

    A metallic 19th century flute was studied by means of integrated and simultaneous neutron-based techniques: neutron diffraction, neutron radiative capture analysis and neutron radiography. This experiment follows benchmark measurements devoted to assessing the effectiveness of a multitask beamline concept for neutron-based investigation on materials. The aim of this study is to show the potential application of the approach using multiple and integrated neutron-based techniques for musical instruments. Such samples, in the broad scenario of cultural heritage, represent an exciting research field. They may represent an interesting link between different disciplines such as nuclear physics, metallurgy and acoustics.

  10. Neutrons field in the neutronic measurements room of the Polytechnic University of Madrid; Campo de neutrones en la sala de medidas neutronicas de la Universidad Politecnica de Madrid

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Gallego, E.; Lorente, A.; Rubio O, I. P., E-mail: hrvegacarrillo@yahoo.com.m [Universidad Politecnica de Madrid, Departamento de Ingenieria Nuclear, C/Jose Gutierrez Abascal No. 2, 28006 Madrid (Spain)

    2010-09-15

    Through of measurements and calculations of a Monte Carlo series has been characterized the neutronic field of the neutronic measurements room of Nuclear Engineering Department of the Polytechnic University of Madrid. The measurements were realized with the Bonner Spheres Spectrometer that allowed establish the spectra on the new stainless steel panel and at different distances measured regarding the source. The values of the speed of environmental equivalent dose were measured with an area monitor Bert hold Lb 6411. Through of Monte Carlo methods was built a detailed model of the room with the panel and the spectra were calculated and, with these the values of the environmental equivalent dose were obtained using the conversion coefficients of the ICRP 74 and the Bert hold Lb 6411 response. The calculated values were compared with those measured and was consistency among the results. (Author)

  11. Study of the neutron skin thickness of ${}^{208}$Pb in mean field models

    CERN Document Server

    Roca-Maza, X; Viñas, X; Warda, M

    2011-01-01

    We study whether the neutron skin thickness $\\Delta r_{np}$ of ${}^{208}$Pb originates from the bulk or from the surface of the neutron and proton density distributions in mean field models. We find that the size of the bulk contribution to $\\Delta r_{np}$ of ${}^{208}$Pb strongly depends on the slope of the nuclear symmetry energy, while the surface contribution does not. We note that most mean field models predict a neutron density for ${}^{208}$Pb between the halo and skin type limits. We investigate the dependence of parity- violating electron scattering at the kinematics of the PREX experiment on the shape of the nucleon densities predicted by the mean field models for ${}^{208}$Pb. We find an approximate formula for the parity-violating asymmetry in terms of the central radius and the surface diffuseness of the nucleon densities of ${}^{208}$Pb in these models.

  12. Quantification of the sensitivity range in neutron dark-field imaging.

    Science.gov (United States)

    Betz, B; Harti, R P; Strobl, M; Hovind, J; Kaestner, A; Lehmann, E; Van Swygenhoven, H; Grünzweig, C

    2015-12-01

    In neutron grating interferometry, the dark-field image visualizes the scattering properties of samples in the small-angle and ultra-small-angle scattering range. These angles correspond to correlation lengths from several hundred nanometers up to several tens of micrometers. In this article, we present an experimental study that demonstrates the potential of quantitative neutron dark-field imaging. The dark-field signal for scattering from different particle sizes and concentrations of mono-dispersive polystyrene particles in aqueous solution is compared to theoretical predictions and the good agreement between measurements and calculations underlines the quantitative nature of the measured values and reliability of the technique with neutrons. PMID:26724039

  13. Neutron Stars in Relativistic Mean Field Theory with Isovector Scalar Meson

    CERN Document Server

    Kubis, S; Stachniewicz, S

    1998-01-01

    We study the equation of state of beta-stable dense matter and models of neutron stars in the relativistic mean field theory with the isovector scalar mean field corresponding to the delta-meson [a_0(980)]. A range of values of the delta-meson coupling compatible with the Bonn potentials is explored. Parameters of the model in the isovector sector are constrained to fit the nuclear symmetry energy, E_s=30 MeV. We find that the quantity most sensitive to the delta-meson coupling is the proton fraction of neutron star matter. It increases significantly in the presence of the delta-field. The energy per baryon also increases but the effect is smaller. The equation of state becomes slightly stiffer and the maximum neutron star mass increases for stronger delta-meson coupling.

  14. Measurements of H*(10) in reference neutron fields using Bonner sphere spectrometry and LET spectrometry

    CERN Document Server

    Golnik, N; Králik, M

    2002-01-01

    A Bonner sphere spectrometer and the REM-2 recombination chamber were used for inter-comparison measurements of the neutron component of ambient dose equivalent, H sub n *(10) in reference neutron fields. The sup 2 sup 4 sup 1 Am-Be and sup 2 sup 5 sup 2 Cf neutron sources were exposed either free-in-air or placed in iron or paraffin filters. The REM-2 recombination chamber was used as a LET spectrometer. The agreement of H sub n *(10) values measured with both the methods was within experimental uncertainties of few percent. The determined neutron spectra were used for calculations of the REM-2 chamber response to H*(10).

  15. Characterization of the neutron field of the 241AmBe in a calibration room

    International Nuclear Information System (INIS)

    The field of neutrons produced by an isotopic source of neutrons of 241 Am Be had been characterized. The characterization was carried out modeling those relevant details of the calibration room and simulating the neutron transport at different distances of the source. The calculated spectra were used to determine the equivalent environmental dose rate. A series of experiments were carried out with the Bonner sphere spectrometric system to measure the spectra in the same points where the calculations were carried out and with these spectra the rates of environmental dose were calculated. By means of a one sphere dosemeter type Berthold the rates of environmental dose were measured. To the one to compare the calculated spectra and measured its were found small differences in the group of the thermal neutrons due to the elementary composition used during the simulation. When comparing the derived rates starting from the calculated spectra with those measured it was found a maxim difference smaller to 13%. (Author)

  16. Neutron field for activation experiments in horizontal channel of training reactor VR-1

    International Nuclear Information System (INIS)

    The experimental channels of nuclear reactors often serve for nuclear data measurement and validation. The dosimetry-foils activation technique was employed to measure neutron field parameters in the horizontal radial channel of the training reactor VR-1, and to test the possibility of using the reactor for scientific purposes. The reaction rates, energy spectral indexes, and neutron spectrum at several irradiation positions of the experimental channel were determined. The experimental results show the feasibility of the radial channel for irradiating experiments and open new possibilities for data validation by using this nuclear facility. - Highlights: • Neutron activation analysis of various samples. • Neutron spectrometry and gamma-spectrometry. • Study of keff for various types of reactor core

  17. A Method for evaluating personal dosemeters in workplace with neutron fields

    International Nuclear Information System (INIS)

    Passive detectors, as albedo or track-etch, still dominate the field of neutron personal dosimetry, mainly due to their low-cost, high-reliability and elevated throughput. However, the recent appearance in the market of electronic personal dosemeters for neutrons presents a new option for personal dosimetry. In addition to passive detectors, electronic personal dosemeters necessitate correction factors, concerning their energy and angular response dependencies. This paper reports on the results of a method to evaluate personal dosemeters for workplace where neutrons are present. The approach here uses few instruments and does not necessitate a large mathematical workload. Qualitative information on the neutron energy spectrum is acquired using a simple spectrometer (Nprobe), reference values for H*(10) are derived from measurements with ambient detectors (Studsvik, Berthold and Harwell) and angular information is measured using personal dosemeters (electronic and bubbles dosemeters) disposed in different orientations on a slab phantom. (authors)

  18. Effect of the neutron field profile on the power reactor stability

    International Nuclear Information System (INIS)

    A technique has been developed for calculating the power reactor stability at an arbitrary stationary power distribution. To describe the neutron balance the one-group diffusion equation in a cylindrical geometry is used. Using computer calculations a table of parameters has been obtained which can be taken advantage of to calculate the period of instability development for the first azimut.hal harmonics as a function of the field deformation, provided that reactivity effects are available. A lowered level of the neutron flux distribution in the centre of the core is demonstrated to effect significantly the period of instability development. For example, if the neutron flux in the centre of the core is 30% lower than at the periphery, than the period is decreases 1.5 times as compared to that in case of the flat neutron flux distribution

  19. The measurement of neutron and neutron induced photon spectra in fusion reactor related assemblies

    CERN Document Server

    Unholzer, S; Klein, H; Seidel, K

    2002-01-01

    The spectral neutron and photon fluence (or flux) measured outside and inside of assemblies related to fusion reactor constructions are basic quantities of fusion neutronics. The comparison of measured spectra with the results of MCNP neutron and photon transport calculations allows a crucial test of evaluated nuclear data as generally used in fusion applications to be carried out. The experiments concern mixed neutron/photon fields with about the same intensity of the two components. An NE-213 scintillation spectrometer, well described by response matrices for both neutrons and photons, is used as proton-recoil and Compton spectrometer. The experiments described here in more detail address the background problematic of two applications, an iron benchmark experiment with an ns-pulsed neutron source and a deep penetration mock-up experiment for the investigation of the ITER in-board shield system. The measured spectral neutron and photon fluences are compared with spectra calculated with the MCNP code on the b...

  20. The measurement of internal stress fields in weldments and around cracks using high resolution neutron diffraction

    International Nuclear Information System (INIS)

    The paper describes and illustrates the capability of neutron diffraction to measure the complete internal lattice macrostrain field, and hence the stress field, within steel components and weldments arising from their fabrication. A brief outline is given of the theory of the neutron method. The experimental considerations are discussed. The method is illustrated by its application to the measurement of the stress distribution in a:- uniaxially stressed mild steel rod, a double - V test weld, a tube-plate weld, and a cracked fatigue test specimen. (U.K.)

  1. The influence of the energy distribution of workplace fields on neutron personal dosemeter reading

    International Nuclear Information System (INIS)

    Variations in the energy dependence of response of neutron personal dosemeters cause systematic errors in the readings obtained in workplace fields. The magnitude of these errors has been determined theoretically by folding measured and calculated workplace energy distributions with dosemeter response functions, to determine the response of a given personal dosemeter in that field. These results have been analysed with consideration of the dosemeter response to various calibration spectra, and with reference to different workplaces. The dosemeters in the study are discussed in terms of the workplaces for which they can be suitably calibrated. Deficiencies in the published neutron energy distributions are identified

  2. Crystalline Electric Field Levels in the Neodymium Monopnictides Determined by Neutron Spectroscopy

    DEFF Research Database (Denmark)

    Furrer, A.; Kjems, Jørgen; Vogt, O.

    1972-01-01

    Neutron inelastic scattering experiments have been carried out to determine the energies and widths of the crystalline electric field levels in the neodymium monopnictides NdP, NdAs, and NdSb. The energy level sequence is derived from the observed crystal field transition peak intensities, which ...... are in good agreement with calculations based on elementary crystal field theory. The energy level widths are qualitatively discussed. It is found that the point-charge model cannot reproduce the crystal field levels satisfactorily.......Neutron inelastic scattering experiments have been carried out to determine the energies and widths of the crystalline electric field levels in the neodymium monopnictides NdP, NdAs, and NdSb. The energy level sequence is derived from the observed crystal field transition peak intensities, which...

  3. Accessing Interior Vector Magnetic Field Components in Neutron EDM Experiments via Boundary Value Techniques

    Science.gov (United States)

    Plaster, Brad

    2012-10-01

    We propose a new technique for the determination and monitoring of the interior vector magnetic field components during the operation of neutron EDM experiments. If a suitable three-dimensional volume surrounding the fiducial volume of an experiment can be defined which contains no interior currents or magnetization, each of the interior vector field components will satisfy the Laplace Equation within this volume. Therefore, if the field components can be measured on the boundary, the interior vector field components can be determined uniquely via numerical solution of the Laplace Equation. We discuss the applicability of this technique to the determination of the magnetic field components and magnetic field gradients in the fiducial volumes of neutron EDM experiments.

  4. Comparison of Out-Of-Field Neutron Equivalent Doses in Scanning Carbon and Proton Therapies for Cranial Fields

    DEFF Research Database (Denmark)

    Athar, B.; Henker, K.; Jäkel, O.;

    Purpose: The purpose of this analysis is to compare the secondary neutron lateral doses from scanning carbon and proton beam therapies. Method and Materials: We simulated secondary neutron doses for out-of-field organs in an 11-year old male patient. Scanned carbon and proton beams were simulated...... separately using Monte Carlo techniques. We have used circular aperture field of 6 cm in diameter as a representative field. The tumor was assumed to be in the cranium. The range and modulation width for both carbon and proton beams were set to 15 cm and 10 cm, respectively. Results: In carbon therapy......, absorbed neutron doses to tonsils and pharynx close to the field-edge were found to be 5x10-4 mSv/GyE and 4x10-4 mSv/GyE, respectively. Whereas, neutron equivalent doses to tonsils and pharynx were estimated to be 0.57mSv/GyE and 0.55 mSv/GyE in scanned proton therapy, respectively. In heavy ion carbon...

  5. Probing into Magnetic Field and Initial Period of Neutron Star

    Institute of Scientific and Technical Information of China (English)

    BAI Hua; PENG Qiu-He

    2004-01-01

    Using the hybrid model and the neutrino jet rocket model, we calculate the magnetic fields and the initial periods of 72 pulsars. We probe into the possible connection among magnetic field, initial period, and initial quantum number.

  6. Quantitative Neutron Dark-field Imaging through Spin-Echo Interferometry.

    Science.gov (United States)

    Strobl, Markus; Sales, Morten; Plomp, Jeroen; Bouwman, Wim G; Tremsin, Anton S; Kaestner, Anders; Pappas, Catherine; Habicht, Klaus

    2015-01-01

    Neutron dark-field imaging constitutes a seminal progress in the field of neutron imaging as it combines real space resolution capability with information provided by one of the most significant neutron scattering techniques, namely small angle scattering. The success of structural characterizations bridging the gap between macroscopic and microscopic features has been enabled by the introduction of grating interferometers so far. The induced interference pattern, a spatial beam modulation, allows for mapping of small-angle scattering signals and hence addressing microstructures beyond direct spatial resolution of the imaging system with high efficiency. However, to date the quantification in the small angle scattering regime is severely limited by the monochromatic approach. To overcome such drawback we here introduce an alternative and more flexible method of interferometric beam modulation utilizing a spin-echo technique. This novel method facilitates straightforward quantitative dark-field neutron imaging, i.e. the required quantitative microstructural characterization combined with real space image resolution. For the first time quantitative microstructural reciprocal space information from small angle neutron scattering becomes available together with macroscopic image information creating the potential to quantify several orders of magnitude in structure sizes simultaneously. PMID:26560644

  7. Population synthesis studies of isolated neutron stars with magnetic field decay

    CERN Document Server

    Popov, S B; Miralles, J A; Boldin, P A; Posselt, B

    2009-01-01

    We perform population synthesis studies of different types of neutron stars (thermally emitting isolated neutron stars, normal radio pulsars, magnetars) taking into account the magnetic field decay and using results from the most recent advances in neutron star cooling theory. For the first time, we confront our results with observations using {\\it simultaneously} the Log N -- Log S distribution for nearby isolated neutron stars, the Log N -- Log L distribution for magnetars, and the distribution of radio pulsars in the $P$ -- $\\dot P$ diagram. For this purpose, we fix a baseline neutron star model (all microphysics input), and other relevant parameters to standard values (velocity distribution, mass spectrum, birth rates ...), allowing to vary the initial magnetic field strength. We find that our theoretical model is consistent with all sets of data if the initial magnetic field distribution function follows a log-normal law with $\\sim 13.25$ and $\\sigma_{\\log B_0}\\sim 0.6$. The typical scenario includes abo...

  8. Comparison of DD, DT and Cf-252 neutron excitation of light and medium mass nuclei for field PGNAA applications

    Energy Technology Data Exchange (ETDEWEB)

    Seabury, E.H. [Idaho National Laboratory, P.O. Box 1625 Idaho Falls, ID 8341-3840 (United States)]. E-mail: Edward.Seabury@inl.gov; Blackburn, B.W. [Idaho National Laboratory, P.O. Box 1625 Idaho Falls, ID 8341-3840 (United States); Chichester, D.L. [Idaho National Laboratory, P.O. Box 1625 Idaho Falls, ID 8341-3840 (United States); Wharton, C.J. [Idaho National Laboratory, P.O. Box 1625 Idaho Falls, ID 8341-3840 (United States); Caffrey, A.J. [Idaho National Laboratory, P.O. Box 1625 Idaho Falls, ID 8341-3840 (United States)

    2007-08-15

    Prompt Gamma Ray Neutron activation analysis can offer significant cost and safety advantages in the identification of explosives and toxic chemicals. As an example, the US military examined over a thousand suspect chemical munitions with Idaho National Laboratory's PINS Chemical Assay System last year. PGNAA requires, of course, a neutron source to excite the atomic nuclei of the item under test via neutron capture and inelastic neutron scattering reactions and the choice of neutron source can drastically affect PGNAA system performance. We have carried out Monte Carlo and laboratory experiments comparing DD, DT and Cf-252 neutrons incident on light and medium mass chemical elements, toward optimizing the design of future neutron-generator-based PGNAA systems for field use. We report the excitation of (n, {gamma}) and (n, n') gamma rays from these elements by each type of neutron source.

  9. Comparison of DD, DT and Cf-252 neutron excitation of light and medium mass nuclei for field PGNAA applications

    International Nuclear Information System (INIS)

    Prompt Gamma Ray Neutron activation analysis can offer significant cost and safety advantages in the identification of explosives and toxic chemicals. As an example, the US military examined over a thousand suspect chemical munitions with Idaho National Laboratory's PINS Chemical Assay System last year. PGNAA requires, of course, a neutron source to excite the atomic nuclei of the item under test via neutron capture and inelastic neutron scattering reactions and the choice of neutron source can drastically affect PGNAA system performance. We have carried out Monte Carlo and laboratory experiments comparing DD, DT and Cf-252 neutrons incident on light and medium mass chemical elements, toward optimizing the design of future neutron-generator-based PGNAA systems for field use. We report the excitation of (n, γ) and (n, n') gamma rays from these elements by each type of neutron source

  10. Comparison of DD, DT and Cf-252 neutron excitation of light and medium mass nuclei for field PGNAA applications

    Science.gov (United States)

    Seabury, E. H.; Blackburn, B. W.; Chichester, D. L.; Wharton, C. J.; Caffrey, A. J.

    2007-08-01

    Prompt Gamma Ray Neutron activation analysis can offer significant cost and safety advantages in the identification of explosives and toxic chemicals. As an example, the US military examined over a thousand suspect chemical munitions with Idaho National Laboratory's PINS Chemical Assay System last year. PGNAA requires, of course, a neutron source to excite the atomic nuclei of the item under test via neutron capture and inelastic neutron scattering reactions and the choice of neutron source can drastically affect PGNAA system performance. We have carried out Monte Carlo and laboratory experiments comparing DD, DT and Cf-252 neutrons incident on light and medium mass chemical elements, toward optimizing the design of future neutron-generator-based PGNAA systems for field use. We report the excitation of (n, γ) and (n, n‧) gamma rays from these elements by each type of neutron source.

  11. A toroidal vortex field as an origin of the narrow mass spectrum of neutron stars

    Science.gov (United States)

    Kontorovich, V. M.

    2016-03-01

    The evolution and collapse of a gaseous, self-gravitating sphere in the presence of an internal massive toroidal vortex analogous to the vortex created by the toroidal magnetic field of the Sun is considered. When thermal pressure is taken into account, for sufficiently high masses, the instability is preserved even for a polytropic index γ neutrons differs appreciably. In the ultrarelativistic limit, an interval of stablemasses arises in a neutron gas, between a minimum mass that depends on the circulation velocity in the vortex and the critical mass for the formation of a black hole. This suggests toroidal vortex fields as a possible physical origin for the observed narrow spectrum of neutron-star masses.

  12. Stationary Electromagnetic Fields of a Slowly Rotating Magnetized Neutron Star in General Relativity

    CERN Document Server

    Rezzolla, L; Miller, J C

    2001-01-01

    Following the general formalism presented by Rezzolla, Ahmedov and Miller (MNRAS, 322, 723 2001), we here derive analytic solutions of the electromagnetic fields equations in the internal and external background spacetime of a slowly rotating highly conducting magnetized neutron star. The star is assumed to be isolated and in vacuum, with a dipolar magnetic field not aligned with the axis of rotation. Our results indicate that the electromagnetic fields of a slowly rotating neutron star are modified by general relativistic effects arising from both the monopolar and the dipolar parts of the gravitational field. The results presented here differ from the ones discussed by Rezzolla, Ahmedov and Miller (MNRAS, 322, 723 2001) mainly in that we here consider the interior magnetic field to be dipolar with the same radial dependence as the external one. While this assumption might not be a realistic one, it should be seen as the application of our formalism to a case often discussed in the literature.

  13. Field ionization characteristics of an ion source array for neutron generators

    Energy Technology Data Exchange (ETDEWEB)

    B. Bargsten Johnson; P. R. Schwoebel; P. J. Resnick; C. E. Holland; L. Hertz; D. L. Chichester

    2013-11-01

    A new deuterium ion source is being developed to improve the performance of existing compact neutron generators. The ion source is a microfabricated array of metal tips with an integrated gate (i.e., grid) and produces deuterium ions by field ionizing (or field desorbing) a supply of deuterium gas. Deuterium field ion currents from arrays at source temperatures of 77?K and 293?K are studied. Ion currents from single etched-wire tips operating under the same conditions are used to help understand array results. I-F characteristics of the arrays were found to follow trends similar to those of the better understood single etched-wire tip results; however, the fields achieved by the arrays are limited by electrical breakdown of the structure. Neutron production by field ionization at 293?K was demonstrated for the first time from microfabricated array structures with integrated gates.

  14. Field ionization characteristics of an ion source array for neutron generators

    Energy Technology Data Exchange (ETDEWEB)

    Bargsten Johnson, B.; Schwoebel, P. R. [University of New Mexico, Albuquerque, New Mexico 87131 (United States); Resnick, P. J. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Holland, C. E. [SRI International, Menlo Park, California 94025 (United States); Hertz, K. L. [Sandia National Laboratories, Livermore, California 94551 (United States); Chichester, D. L. [Idaho National Laboratory, Idaho Falls, Idaho 83415 (United States)

    2013-11-07

    A new deuterium ion source is being developed to improve the performance of existing compact neutron generators. The ion source is a microfabricated array of metal tips with an integrated gate (i.e., grid) and produces deuterium ions by field ionizing (or field desorbing) a supply of deuterium gas. Deuterium field ion currents from arrays at source temperatures of 77 K and 293 K are studied. Ion currents from single etched-wire tips operating under the same conditions are used to help understand array results. I-F characteristics of the arrays were found to follow trends similar to those of the better understood single etched-wire tip results; however, the fields achieved by the arrays are limited by electrical breakdown of the structure. Neutron production by field ionization at 293 K was demonstrated for the first time from microfabricated array structures with integrated gates.

  15. Reproducibility of TL measurements in a mixed field of thermal neutrons and photons.

    Science.gov (United States)

    Fernandes, A C; Gonçalves, I C; Ferro Carvalho, A; Santos, J; Cardoso, J; Santos, L; Osvay, M

    2002-01-01

    The reproducibility of measurements performed with GR-100 (LiF:Mg,Ti) from the Solid Dosimetric Detector and Method Laboratory (DML) China, GR-107 (7LiF:Mg,Ti, DML), TLD-700H (7LiF:Mg.Cu,P, Harshaw) and Al2O3:Mg,Y (Hungary) in photon and mixed photon-neutron fields was investigated. Mixed-field irradiations were performed in a thermal neutron field generated at a nuclear reactor. GR-100 sensitivity decreased after mixed-field irradiations, while no significant change was found for the other materials. Using GR-100 for the dosimetry of mixed and high-intensity fields requires careful procedures. PMID:12382796

  16. Signatures of field induced spin polarization of neutron star matter in seismic vibrations of paramagnetic neutron star

    CERN Document Server

    Bastrukov, S I; Podgainy, D V; Weber, F

    2003-01-01

    A macroscopic model of the dissipative magneto-elastic dynamics of viscous spin polarized nuclear matter is discussed in the context of seismic activity of a paramagnetic neutron star. The source of the magnetic field of such a star is attributed to Pauli paramagnetism of baryon matter promoted by a seed magnetic field frozen into the star in the process of gravitational collapse of a massive progenitor. Particular attention is given to the effect of shear viscosity of incompressible stellar material on the timing of non-radial torsional magneto-elastic pulsations of the star triggered by starquakes. By accentuating the fact that this kind of vibration is unique to the seismology of a paramagnetic neutron star we show that the high-frequency modes decay faster than the low-frequency modes. The obtained analytic expressions for the period and relaxation time of this mode, in which the magnetic susceptibility and viscosity enter as input parameters, are then quantified by numerical estimates for these parameter...

  17. Zero Sound in Neutron Stars with Dense Quark Matter under Strong Magnetic Fields

    DEFF Research Database (Denmark)

    Kouvaris, Christoforos

    2009-01-01

    We study a neutron star with a quark matter core under extremely strong magnetic fields. We investigate the possibility of an Urca process as a mechanism for the cooling of such a star. We found that apart from very particular cases, the Urca process cannot occur. We also study the stability of...

  18. Shape Coexistence in Neutron-Deficient At Isotopes in Relativistic Mean-Field Model

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The potential energy surfaces are calculated for neutron-deficient At isotopes from A = 190 to 207 in an axiaJJy deformed relativistic mean-field approach, using a quadratic constraint scheme for the first time. We find several minima in the potential energy surface for each nucleus, shape-coexistence, and quadratic deform are discussed.

  19. Dependence of TLD thermoluminescence yield on absorbed dose in a thermal neutron field.

    Science.gov (United States)

    Gambarini, G; Roy, M S

    1997-01-01

    The emission from 6LiF and 7LiF thermoluminescence dosimeters (TLDs) exposed to the mixed field of thermal neutrons and gamma-rays of the thermal facility of a TRIGA MARK II nuclear reactor has been investigated for various thermal neutron fluences of the order of magnitude of those utilised in radiotherapy, with the purpose of investigating the reliability of TLD readouts in such radiation fields and of giving some information for better obtainment of the absorbed dose values. The emission after exposure in this mixed field is compared with the emission after gamma-rays only. The glow curves have been deconvoluted into gaussian peaks, and the differences in the characteristics of the peaks observed for the two radiation fields, having different linear energy transfers, and for different doses are shown. Irreversible radiation damage in dosimeters having high sensitivity to thermal neutrons is also reported, showing a memory effect of the previous thermal neutron irradiation history which is not restored by anneal treatment. PMID:9463872

  20. Characterization of Monoenergetic Neutron Reference Fields with a High Resolution Diamond Detector

    CERN Document Server

    Zimbal, A; Nolte, R; Schuhmacher, H

    2009-01-01

    A novel radiation detector based on an artificial single crystal diamond was used to characterize in detail the energy distribution of neutron reference fields at the Physikalisch-Technische Bundesanstalt (PTB) and their contamination with charged particles. The monoenergetic reference fields at PTB in the neutron energy range from 1.5 MeV up to 19 MeV are generated by proton and deuteron beams impinging on solid and gas targets of tritium and deuterium. The energy of the incoming particles and the variation of the angle under which the measurement is performed produce monoenergetic reference fields with different mean energies and line shapes. In this paper we present high resolution neutron spectrometry measurements of different monoenergetic reference fields. The results are compared with calculated spectra taking into account the actual target parameters. Line structures in the order of 80 keV for a neutron energy of 9 MeV were resolved. The shift of the mean energy and the increasing of the width of the ...

  1. Magnetic Field R&D for the neutron EDM experiment at TRIUMF

    Science.gov (United States)

    Mammei, Russell R.

    2014-09-01

    The neutron EDM experiment at TRIUMF aims to constrain the EDM with a precision of 1 ×10-27 e-cm by 2018. The experiment will use a spallation ultracold neutron (UCN) source employing superfluid helium coupled to a room-temperature EDM apparatus. In the previous best experiment, conducted at ILL, effects related to magnetic field homogeneity and instability were found to dominate the systematic error. This presentation will cover our R&D efforts on passive and active magnetic shielding, magnetic field generation within shielded volumes, and precision magnetometry. The neutron EDM experiment at TRIUMF aims to constrain the EDM with a precision of 1 ×10-27 e-cm by 2018. The experiment will use a spallation ultracold neutron (UCN) source employing superfluid helium coupled to a room-temperature EDM apparatus. In the previous best experiment, conducted at ILL, effects related to magnetic field homogeneity and instability were found to dominate the systematic error. This presentation will cover our R&D efforts on passive and active magnetic shielding, magnetic field generation within shielded volumes, and precision magnetometry. Supported by the Canada Foundation for Innovation, the Natural Sciences and Engineering Research Council of Canada, and the Canada Research Chairs program.

  2. Effect of magnetic field decay on the chemical heating of cooling neutron stars

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xia; KANG Miao; WANG Na

    2013-01-01

    The effect of magnetic field decay on the chemical heating and thermal evolution of neutron stars is discussed in this paper.Our main goal is to study how the chemical heating mechanism and thermal evolution are changed by the field decay and how the magnetic field decay is modified by the thermal evolution.We compare stars cooling with chemical heating with one without chemical heating and find that the decay of the magnetic field is delayed significantly by the chemical heating.We find that the effect of chemical heating has been suppressed through the decaying magnetic field by the spin-down of the stars at a later stage.Compared with typical chemical heating,we find the decay of the magnetic field can even cause the surface temperature to turn down at an older age.When we discuss the cooling of neutron stars,we should consider the coupling effect of the magnetic field and the rotational evolution of neutron stars on the heating mechanisms.

  3. Extension of the VITESS polarized neutron suite towards the use of imported magnetic field distributions

    International Nuclear Information System (INIS)

    Latest developments of the polarized neutron suite in the VITESS simulation package allowed for simulations of time-dependent spin handling devices (e.g. radio-frequency (RF) flippers, adiabatic gradient RF-flippers) and the instrumentation built upon them (NRSE, SESANS, MIEZE, etc.). However, till now the magnetic field distribution in such devices have been considered as 'ideal' (sinusoidal, triangular or rectangular), when the main practical interest is in the use of arbitrary magnetic field distributions (either obtained by the field mapping or by FEM calculations) that may significantly influence the performance of real polarized neutron instruments and is the key issue in the practical use of the simulation packages. Here we describe modified VITESS modules opening the possibility to load the magnetic field 3-dimensional space map from an external source (file). Such a map can be either obtained by direct measurements or calculated by dedicated FEM programs (such as ANSYS, MagNet, Maxwell or similar). The successful use of these new modules is demonstrated by a very good agreement of neutron polarimetric experiments with performance of the spin turner with rotating magnetic field and an adiabatic gradient RF-flipper simulated by VITESS using calculated 3-dimensional field maps (using MagNet) and magnetic field mapping, respectively.

  4. Benchmarking water productivity in agriculture and the scope for improvement - remote sensing modelling from field to global scale

    NARCIS (Netherlands)

    Zwart, S.J.

    2010-01-01

    Agriculture is the largest consumer and water. In the context of an increasing population and less water available for the agricultural sector, the water productivity needs to be sustained or increased to secure food security. This study provides benchmark values for water productivity for the major

  5. Consistent neutron star models with magnetic field dependent equations of state

    CERN Document Server

    Chatterjee, Debarati; Novak, Jerome; Oertel, Micaela

    2014-01-01

    We present a self-consistent model for the study of the structure of a neutron star in strong magnetic fields. Starting from a microscopic Lagrangian, this model includes the effect of the magnetic field on the equation of state, the interaction of the electromagnetic field with matter (magnetisation), and anisotropies in the energy-momentum tensor, as well as general relativistic aspects. We build numerical axisymmetric stationary models and show the applicability of the approach with one example quark matter equation of state (EoS) often employed in the recent literature for studies of strongly magnetised neutron stars. For this EoS, the effect of inclusion of magnetic field dependence or the magnetisation do not increase the maximum mass significantly in contrast to what has been claimed by previous studies.

  6. Neutron reflectivity studies of electric field driven structural transformations of surfactants

    CERN Document Server

    Majewski, J; Burgess, I; Zamlynny, V; Szymanski, G; Lipkowski, J; Satija, S

    2002-01-01

    We employed electrochemical methods together with in situ neutron reflectometry to describe the aggregation of organic surfactant molecules at a solid-liquid interface. The neutron reflectometry allowed us to determine the surface coverage, thickness, roughness and the relative positions of the aggregates. We found that the applied electric field may be used to reversibly manipulate the architecture of the organic molecules: from uniform monolayers to adsorbed hemi-micelles. These studies are expected to provide a new insight into the roles played by entropic and electrostatic forces in complex fluids or biomaterials. (orig.)

  7. Pasta phases in neutron star studied with extended relativistic mean field models

    CERN Document Server

    Gupta, Neha

    2013-01-01

    To explain several properties of finite nuclei, infinite matter, and neutron stars in a unified way within the relativistic mean field models, it is important to extend them either with higher order couplings or with density-dependent couplings. These extensions are known to have strong impact in the high-density regime. Here we explore their role on the equation of state at densities lower than the saturation density of finite nuclei which govern the phase transitions associated with pasta structures in the crust of neutron stars.

  8. Measurement of energy and direction distribution of neutron and photon fluences in workplace fields

    International Nuclear Information System (INIS)

    Within the EU Project EVIDOS, a spectrometer with 24 silicon detectors mounted on the surface of a polyethylene sphere is used for the determination of the energy and direction distribution of neutrons and photons. It has been characterized with respect to neutron radiation with energies from thermal up to 15 MeV and to photon radiation with energies from 65 keV to 6 MeV. The first measurements described here were performed in the simulated workplace field, CANEL, at Cadarache, with the purpose of checking the instrument and the unfolding procedures. (authors)

  9. Tidal deformability of neutron and hyperon star with relativistic mean field equations of state

    CERN Document Server

    Kumar, Bharat; Patra, S K

    2016-01-01

    We systematically study the tidal deformability for neutron and hyperon stars using relativistic mean field (RMF) equations of state (EOSs). The tidal effect plays an important role during the early part of the evolution of compact binaries. Although, the deformability associated with the EOSs has a small correction, it gives a clean gravitational wave signature in binary inspiral. These are characterized by various love numbers kl (l=2, 3, 4), that depend on the EOS of a star for a given mass and radius. The tidal effect of star could be efficiently measured through advanced LIGO detector from the final stages of inspiraling binary neutron star (BNS) merger.

  10. Neutron Star masses from the Field Correlator Method Equation of State

    Directory of Open Access Journals (Sweden)

    Zappalà D.

    2014-04-01

    Full Text Available We analyse the hadron-quark phase transition in neutron stars by confronting the hadronic Equation of State (EoS obtained according to the microscopic Brueckner-Hartree-Fock many body theory, with the quark matter EoS derived within the Field Correlator Method. In particular, the latter EoS is only parametrized in terms of the gluon condensate and the large distance quark-antiquark potential, so that the comparison of the results of this analysis with the most recent measurements of heavy neutron star masses provides some physical constraints on these two parameters.

  11. Pulsar Spin-Down by 3P2 Superfluid Neutron with Field Decay

    Institute of Scientific and Technical Information of China (English)

    LUO Xin-Lian; PENG Qiu-He; CHOU Chih-Kang

    2003-01-01

    To describe pulsar spin-down, we present a simple combined torque model that takes into account both the standard magnetic dipole radiation and the electromagnetic radiation from the 3P2 superSuid vortex neutrons inside neutron star. Using an ordinary exponential model for the magnetic field decay, we derive an analytical formulae for pulsar evolution tracks. The pulsar evolution on the P-P diagram is quite different from that of the standard magnetic dipole radiation model, especially when the supernuid torque or Geld decay becomes dominant.

  12. Visualization of electric field in ion conductive oxides using neutron computed tomography

    International Nuclear Information System (INIS)

    Neutron computed tomography was applied to visualize of electric field in the spinel-type lithium conductive oxide Li1.33Ti1.67O4. Distribution of lithium ion in the specimen was able to be visualized by this method. Considering the distribution of lithium ion inserted through point interface, the electric field formed in the specimen appeared to be similar to that of metallic conductor. (author)

  13. Benchmarking for Best Practice

    CERN Document Server

    Zairi, Mohamed

    1998-01-01

    Benchmarking for Best Practice uses up-to-the-minute case-studies of individual companies and industry-wide quality schemes to show how and why implementation has succeeded. For any practitioner wanting to establish best practice in a wide variety of business areas, this book makes essential reading. .It is also an ideal textbook on the applications of TQM since it describes concepts, covers definitions and illustrates the applications with first-hand examples. Professor Mohamed Zairi is an international expert and leading figure in the field of benchmarking. His pioneering work in this area l

  14. On observation of neutron quantum states in the Earth's gravitational field

    Science.gov (United States)

    Vankov, Anatoli Andrei

    2010-03-01

    Observation of neutron gravitational quantum states En=mgzn in the peV energy range (z1 is about 10μm in the vertical direction) in the experiment conducted at Laue-Langevin Institute, Grenoble, with ultracold neutrons was recently reported in a series of publications. The purpose of the present work is to analyze the experiment. The experimental apparatus is designed to measure a transmission function T(za), namely, a horizontal flux of relatively fast neutrons (k≫kz in wavelength terms) passing through a slit of variable height za of upper absorbing wall. The quantum states in question are defined by the so-called Airy functions, which are solutions to the stationary 1D equation for a neutron “bouncing” above the perfect mirror in a linear potential field. The Airy functions describe the quantum bouncer (QB), the concept of which is subject to theoretical study of toy 1D models of gravitationally bound particles in nonrelativistic quantum mechanics (QM). This is essentially different from the 3D nonstationary QM object, “the running QB,” investigated in the experiment. The authors assume that there is a connection between T(za) and the probability density distribution P(z,za) for QB states. They devised the “phenomenological model,” in which the quantum pattern should be visible in the transmission curve. We argue, however, that the measured curve T(za) is not sensitive to QB states. Instead, it is sensitive to dynamics of neutron horizontal transport inside the absorbing slit for neutrons of energy values about 105 times greater than eigenvalues En. The latter are related to the neutron transverse mode kz and cannot be termed “energies of neutron gravitational quantum states.” We conclude that the experiment setup and real conditions are not adequate to the claimed objective, and the methodology of measured data treatment is flawed. The authors’ claim that “neutron gravitational quantum states are observed” is neither theoretically nor

  15. A comprehensive spectrometry study of a stray neutron radiation field in scanning proton therapy

    Science.gov (United States)

    Mares, Vladimir; Romero-Expósito, Maite; Farah, Jad; Trinkl, Sebastian; Domingo, Carles; Dommert, Martin; Stolarczyk, Liliana; Van Ryckeghem, Laurent; Wielunski, Marek; Olko, Pawel; Harrison, Roger M.

    2016-06-01

    The purpose of this study is to characterize the stray neutron radiation field in scanning proton therapy considering a pediatric anthropomorphic phantom and a clinically-relevant beam condition. Using two extended-range Bonner sphere spectrometry systems (ERBSS), Working Group 9 of the European Radiation Dosimetry Group measured neutron spectra at ten different positions around a pediatric anthropomorphic phantom irradiated for a brain tumor with a scanning proton beam. This study compares the different systems and unfolding codes as well as neutron spectra measured in similar conditions around a water tank phantom. The ten spectra measured with two ERBSS systems show a generally similar thermal component regardless of the position around the phantom while high energy neutrons (above 20 MeV) were only registered at positions near the beam axis (at 0°, 329° and 355°). Neutron spectra, fluence and ambient dose equivalent, H *(10), values of both systems were in good agreement (Gy‑1 was measured at 329° to the beam axis and 1.63 m from the isocenter where high-energy neutrons (E  ⩾  20 MeV) contribute with about 53%. The neutron mapping within the gantry room showed that H *(10) values significantly decreased with distance and angular position with respect to the beam axis dropping to 0.52 μSv Gy‑1 at 90° and 3.35 m. Spectra at angles of 45° and 135° with respect to the beam axis measured here with an anthropomorphic phantom showed a similar peak structure at the thermal, fast and high energy range as in the previous water-tank experiments. Meanwhile, at 90°, small differences at the high-energy range were observed. Using ERBSS systems, neutron spectra mapping was performed to characterize the exposure of scanning proton therapy patients. The ten measured spectra provide precise information about the exposure of healthy organs to thermal, epithermal, evaporation and intra-nuclear cascade neutrons. This comprehensive spectrometry analysis

  16. Neutron star deformation due to arbitrary-order multipolar magnetic fields

    CERN Document Server

    Mastrano, Alpha; Melatos, Andrew

    2013-01-01

    Certain multi-wavelength observations of neutron stars, such as intermittent radio emissions from rotation-powered pulsars beyond the pair-cascade death line, the pulse profile of the magnetar SGR 1900+14 after its 1998 August 27 giant flare, and X-ray spectral features of PSR J0821-4300 and SGR 0418+5729, suggest that the magnetic fields of non-accreting neutron stars are not purely dipolar and may contain higher-order multipoles. Here, we calculate the ellipticity of a non-barotropic neutron star with (i) a quadrupole poloidal-toroidal field, and (ii) a purely poloidal field containing arbitrary multipoles, deriving the relation between the ellipticity and the multipole amplitudes. We present, as a worked example, a purely poloidal field comprising dipole, quadrupole, and octupole components. We show the correlation between field energy and ellipticity for each multipole, that the l=4 multipole has the lowest energy, and that l=5 has the lowest ellipticity. We show how a mixed multipolar field creates an ob...

  17. Hypercritical Accretion onto a Newborn Neutron Star and Magnetic Field Submergence

    CERN Document Server

    Bernal, Cristian G; Lee, William H

    2012-01-01

    We present magnetohydrodynamic numerical simulations of the late post-supernova hypercritical accretion to understand its effect on the magnetic field of the new-born neutron star. We consider as an example the case of a magnetic field loop protruding from the star's surface. The accreting matter is assumed to be non magnetized and, due to the high accretion rate, matter pressure dominates over magnetic pressure. We find that an accretion envelope develops very rapidly and once it becomes convectively stable the magnetic field is easily buried and pushed into the newly forming neutron star crust. However, for low enough accretion rates the accretion envelope remains convective for an extended period of time and only partial submergence of the magnetic field occurs due to a residual field that is maintained at the interface between the forming crust and the convective envelope. In this latter case, the outcome should be a weakly magnetized neutron star with a likely complicated field geometry. In our simulatio...

  18. Sensitivity Reach of the Neutron EDM Experiment: The Electric Field Strength

    International Nuclear Information System (INIS)

    The search for an electric dipole moment of the neutron tests physics beyond the Standard Model such as new sources of CP-violation and Supersymmetry. The nEDM experiment aims to improve the sensitivity on the current limit of the electric dipole moment of the neutron to -27 e·cm. The experiment will use a flux of Ultra Cold Neutrons (UCNs) produced and stored in a bath of superfluid He-II. A change in precession frequency is expected for a non-zero EDM when an electric field is applied parallel and antiparallel to a magnetic field across the neutron storage cell. A dominant parameter in terms of reducing the statistical uncertainty of this measurement is the strength of the applied electric field. An experiment to measure if superfluid He-II can sustain up to 50 kV/cm for a volume and electrode spacings comparable to the nEDM experiment has been constructed at Los Alamos National Laboratory. It consists in a large-area parallel plate capacitor immersed in a 200 liter central volume inside a suitable cryostat that in turn is connected to a dilution refrigerator unit. A description of test runs and the status of the experiment is presented.

  19. Monte Carlo simulation of mixed neutron-gamma radiation fields and dosimetry devices

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guoqing

    2011-12-22

    Monte Carlo methods based on random sampling are widely used in different fields for the capability of solving problems with a large number of coupled degrees of freedom. In this work, Monte Carlos methods are successfully applied for the simulation of the mixed neutron-gamma field in an interim storage facility and neutron dosimeters of different types. Details are discussed in two parts: In the first part, the method of simulating an interim storage facility loaded with CASTORs is presented. The size of a CASTOR is rather large (several meters) and the CASTOR wall is very thick (tens of centimeters). Obtaining the results of dose rates outside a CASTOR with reasonable errors costs usually hours or even days. For the simulation of a large amount of CASTORs in an interim storage facility, it needs weeks or even months to finish a calculation. Variance reduction techniques were used to reduce the calculation time and to achieve reasonable relative errors. Source clones were applied to avoid unnecessary repeated calculations. In addition, the simulations were performed on a cluster system. With the calculation techniques discussed above, the efficiencies of calculations can be improved evidently. In the second part, the methods of simulating the response of neutron dosimeters are presented. An Alnor albedo dosimeter was modelled in MCNP, and it has been simulated in the facility to calculate the calibration factor to get the evaluated response to a Cf-252 source. The angular response of Makrofol detectors to fast neutrons has also been investigated. As a kind of SSNTD, Makrofol can detect fast neutrons by recording the neutron induced heavy charged recoils. To obtain the information of charged recoils, general-purpose Monte Carlo codes were used for transporting incident neutrons. The response of Makrofol to fast neutrons is dependent on several factors. Based on the parameters which affect the track revealing, the formation of visible tracks was determined. For

  20. Monte Carlo simulation of mixed neutron-gamma radiation fields and dosimetry devices

    International Nuclear Information System (INIS)

    Monte Carlo methods based on random sampling are widely used in different fields for the capability of solving problems with a large number of coupled degrees of freedom. In this work, Monte Carlos methods are successfully applied for the simulation of the mixed neutron-gamma field in an interim storage facility and neutron dosimeters of different types. Details are discussed in two parts: In the first part, the method of simulating an interim storage facility loaded with CASTORs is presented. The size of a CASTOR is rather large (several meters) and the CASTOR wall is very thick (tens of centimeters). Obtaining the results of dose rates outside a CASTOR with reasonable errors costs usually hours or even days. For the simulation of a large amount of CASTORs in an interim storage facility, it needs weeks or even months to finish a calculation. Variance reduction techniques were used to reduce the calculation time and to achieve reasonable relative errors. Source clones were applied to avoid unnecessary repeated calculations. In addition, the simulations were performed on a cluster system. With the calculation techniques discussed above, the efficiencies of calculations can be improved evidently. In the second part, the methods of simulating the response of neutron dosimeters are presented. An Alnor albedo dosimeter was modelled in MCNP, and it has been simulated in the facility to calculate the calibration factor to get the evaluated response to a Cf-252 source. The angular response of Makrofol detectors to fast neutrons has also been investigated. As a kind of SSNTD, Makrofol can detect fast neutrons by recording the neutron induced heavy charged recoils. To obtain the information of charged recoils, general-purpose Monte Carlo codes were used for transporting incident neutrons. The response of Makrofol to fast neutrons is dependent on several factors. Based on the parameters which affect the track revealing, the formation of visible tracks was determined. For

  1. Distributions of neutron and gamma doses in phantom under a mixed field

    International Nuclear Information System (INIS)

    A calculation program, based on Monte Carlo method, allowed to estimate the absorbed doses relatives to the reactor primary radiation, in a water cubic phantom and in cylindrical phantoms modelized from tissue compositions. This calculation is a theoretical approach of gamma and neutron dose gradient study in an animal phantom. PIN junction dosimetric characteristics have been studied experimentally. Air and water phantom radiation doses measured by PIN junction and lithium 7 fluoride, in reactor field have been compared to doses given by dosimetry classical techniques as tissue equivalent plastic and aluminium ionization chambers. Dosimeter responses have been employed to evaluate neutron and gamma doses in plastinaut (tissue equivalent plastic) and animal (piglet). Dose repartition in the piglet bone medulla has been also determined. This work has been completed by comparisons with Doerschell, Dousset and Brown results and by neutron dose calculations; the dose distribution related to lineic energy transfer in Auxier phantom has been also calculated

  2. X-ray studies of neutron stars and their magnetic fields

    Science.gov (United States)

    MAKISHIMA, Kazuo

    2016-01-01

    Utilizing results obtained over the past quarter century mainly with Japanese X-ray astronomy satellites, a review is given to some aspects of neutron stars (NSs), with a particular emphasis on the magnetic fields (MFs) of mass-accreting NSs and magnetars. Measurements of electron cyclotron resonance features in binary X-ray pulsars, using the Ginga and Suzaku observatories, clarified that their surface MFs are concentrated in a narrow range of (1–7) × 108 T. Extensive studies of magnetars with Suzaku reinforced their nature as neutron stars with truly strong MFs, and revealed several important clues to their formation, evolution, and physical states. Taking all these results into account, a discussion is made on the origin and evolution of these strong MFs. One possible scenario is that the MF of NSs is a manifestation of some fundamental physics, e.g., neutron spin alignment or chirality violation, and the MF makes transitions from strong to weak states. PMID:27169348

  3. Neutrino energy loss by electron capture in magnetic field at the crusts of neutron stars

    Institute of Scientific and Technical Information of China (English)

    LIU Jing-Jing; LUO Zhi-Quan

    2008-01-01

    Based on the p-f shell model,the effect of strong magnetic field on neutrino energy loss rates by electron capture is investigated.The calculations show that the magnetic field has only a slight effect on the neutrino energy loss rates in the range of 108-1013 G on the surfaces of most neutron stars.But for some magnetars,the range of the magnetic field is 1013-1018 G,and the neutrino energy loss rates are greatly reduced,even by more than four orders of magnitude due to the strong magnetic field.

  4. The design of the inelastic neutron scattering mode for the Extreme Environment Diffractometer with the 26 T High Field Magnet

    Energy Technology Data Exchange (ETDEWEB)

    Bartkowiak, Maciej, E-mail: maciej.bartkowiak@helmholtz-berlin.de; Stüßer, Norbert; Prokhnenko, Oleksandr

    2015-10-11

    The Extreme Environment Diffractometer is a neutron time-of-flight instrument, designed to work with a constant-field hybrid magnet capable of reaching fields over 26 T, unprecedented in neutron science; however, the presence of the magnet imposes both spatial and technical limitations on the surrounding instrument components. In addition to the existing diffraction and small-angle neutron scattering modes, the instrument will operate also in an inelastic scattering mode, as a direct time-of-flight spectrometer. In this paper we present the Monte Carlo ray-tracing simulations, the results of which illustrate the performance of the instrument in the inelastic-scattering mode. We describe the focussing neutron guide and the chopper system of the existing instrument and the planned design for the instrument upgrade. The neutron flux, neutron spatial distribution, divergence distribution and energy resolution are calculated for standard instrument configurations.

  5. Application of an ultraminiature thermal neutron monitor for irradiation field study of accelerator-based neutron capture therapy

    OpenAIRE

    Ishikawa, Masayori; Tanaka, Kenichi; Endo, Satrou; Hoshi, Masaharu

    2015-01-01

    Phantom experiments to evaluate thermal neutron flux distribution were performed using the Scintillator with Optical Fiber (SOF) detector, which was developed as a thermal neutron monitor during boron neutron capture therapy (BNCT) irradiation. Compared with the gold wire activation method and Monte Carlo N-particle (MCNP) calculations, it was confirmed that the SOF detector is capable of measuring thermal neutron flux as low as 105 n/cm2/s with sufficient accuracy. The SOF detector will be u...

  6. Application of an ultraminiature thermal neutron monitor for irradiation field study of accelerator-based neutron capture therapy

    OpenAIRE

    Ishikawa, Masayori; Tanaka, Kenichi; Endo, Satrou; Hoshi, Masaharu

    2015-01-01

    Phantom experiments to evaluate thermal neutron flux distribution were performed using the Scintillator with Optical Fiber (SOF) detector, which was developed as a thermal neutron monitor during boron neutron capture therapy (BNCT) irradiation. Compared with the gold wire activation method and Monte Carlo N-particle (MCNP) calculations, it was confirmed that the SOF detector is capable of measuring thermal neutron flux as low as 105 n/cm2/s with sufficient accuracy. The SOF detector ...

  7. Magnetic field dependence of the neutron spin resonance in CeB6

    Science.gov (United States)

    Portnichenko, P. Y.; Demishev, S. V.; Semeno, A. V.; Ohta, H.; Cameron, A. S.; Surmach, M. A.; Jang, H.; Friemel, G.; Dukhnenko, A. V.; Shitsevalova, N. Yu.; Filipov, V. B.; Schneidewind, A.; Ollivier, J.; Podlesnyak, A.; Inosov, D. S.

    2016-07-01

    In zero magnetic field, the famous neutron spin resonance in the f -electron superconductor CeCoIn5 is similar to the recently discovered exciton peak in the nonsuperconducting CeB6. A magnetic field splits the resonance in CeCoIn5 into two components, indicating that it is a doublet. Here we employ inelastic neutron scattering (INS) to scrutinize the field dependence of spin fluctuations in CeB6. The exciton shows a markedly different behavior without any field splitting. Instead, we observe a second field-induced magnon whose energy increases with field. At the ferromagnetic zone center, however, we find only a single mode with a nonmonotonic field dependence. At low fields, it is initially suppressed to zero together with the antiferromagnetic order parameter, but then reappears at higher fields inside the hidden-order phase, following the energy of an electron spin resonance (ESR). This is a unique example of a ferromagnetic resonance in a heavy-fermion metal seen by both ESR and INS consistently over a broad range of magnetic fields.

  8. Neutron Radiography

    OpenAIRE

    Reddy, A. R.; Rao, M. V. N.

    2012-01-01

    The field of neutron radiography with special reference to isotopic neutron radiography has been reviewed. Different components viz., sources, collimators, imaging systems are described. Various designs of neutron radiography facilities, their relative merits and demerits , the appropriateness of each design depending on the object to be radiographed, and economics of each technique are also dealt. The applications of neutron radiography are also briefly presented.

  9. Neutron investigations of magnetic properties of crystal substances with use of a pulsed magnetic field

    CERN Document Server

    Nitts, V V

    2001-01-01

    Bases for neutron researches of magnetic properties of crystal substances with use of a pulsed magnetic field and analysis of possible application of various neutron sources in this area are submitted. The review of the most interesting physical results is presented. Main investigations on pulsed reactors of JINR are researches on kinetics of the first order reorientational phase transitions induced in single crystals, and also measurements of antiferromagnetic ordering induced by an external magnetic field. Magnetic phase transitions, induced by a field up to 160 kOe in several magnetic ordering substances, were studied in KEK (Japan). Experiment on observation of spin-flop transition in MnF sub 2 was carried out on TRIGA-reactor in a mode of single flashes of power

  10. Energy and direction distribution of neutrons in workplace fields: Implication of the results from the EVIDOS project for the set-up of simulated workplace fields

    International Nuclear Information System (INIS)

    Workplace neutron spectra from nuclear facilities obtained within the European project EVIDOS are compared with those of the simulated workplace fields CANEL and SIGMA and fields set-up with radionuclide sources at the PTB. Contributions of neutrons to ambient dose equivalent and personal dose equivalent are given in three energy intervals (for thermal, intermediate and fast neutrons) together with the corresponding direction distribution, characterised by three different types of distributions (isotropic, weakly directed and directed). The comparison shows that none of the simulated workplace fields investigated here can model all the characteristics of the fields observed at power reactors. (authors)

  11. Effects of Magnetic Field Topology in Black Hole-Neutron Star Mergers: Long-Term Simulations

    CERN Document Server

    Wan, Mew-Bing

    2016-01-01

    We report long-term simulations of black hole-neutron star binary mergers where the neutron star possesses an asymmetric magnetic field dipole. Focusing on the scenario where the neutron star is tidally disrupted by the black hole, we track the evolution of the binary up to $\\approx 100$ms after merger. We uncover more than one episode of thermally driven winds being launched along a funnel wall in all these cases beginning from $\\approx 25$ms after merger. The emission rate of the second wind episode is found to increase with the degree of asymmetry. A large-scale poloidal magnetic field configuration is formed along the funnel wall accompanied by the generation of a large Poynting flux. The magnetic field in the accretion disk around the black hole remnant is amplified by the non-axisymmetric magneto-rotational instability. However, the asymmetry in the magnetic field leads to increased turbulence which causes the poloidal magnetic field in the accretion disk to grow largely in a non-linear manner.

  12. Simultaneous soil moisture and properties estimation for a drip irrigated field by assimilating cosmic-ray neutron intensity

    OpenAIRE

    Han, Xujun; Franssen, Harrie-Jan Hendricks; Bello, Miguel Ángel Jiménez; Rosolem, Rafael; Bogena, Heye; Alzamora, Fernando Martínez; Chanzy, André; Vereecken, Harry

    2016-01-01

    Neutron intensity measured by the aboveground cosmic-ray neutron intensity probe (CRP) allows estimating soil moisture content at the field scale. In this work, synthetic neutron intensities were used to remove the bias of simulated soil moisture content or update soil hydraulic properties (together with soil moisture) in the Community Land Model (CLM) using the Local Ensemble Transform Kalman Filter. The cosmic-ray forward model COSMIC was used as the non-linear measurement operator which ma...

  13. DOSIMETRIC response of a REM-500 in low energy neutron fields typical of nuclear power plants.

    Science.gov (United States)

    Aslam; Matysiak, W; Atanackovic, J; Waker, A J

    2012-06-01

    This study investigates the response of a REM-500 to assess neutron quality factor and dose equivalent in low energy neutron fields, which are commonly encountered in the workplace environment of nuclear power stations. The McMaster University 3 MV Van de Graaff accelerator facility was used to measure the response of the instrument in monoenergetic neutron fields in the energy range 51 to 727 keV by bombarding a thin LiF target with 1.93-2.50 MeV protons. The energy distribution of the neutron fields produced in the facility was measured by a (3)He filled gas ionization chamber. The MCA mode of the REM-500 instrument was used to collect lineal energy distributions at varying neutron energies and to calculate the frequency and dose-mean lineal energies. The effective quality factor, Q-, was also calculated using the values of Q(y)listed in the REM-500 operation manual and compared with those of ICRP 60. The authors observed a continuously increasing trend in y - F, y-D, and Q-with an increase in neutron energy. It is interesting to note that standard tissue equivalent proportional counters (TEPCs) filled with tissue equivalent(TE) gas give rise to a similar trend for these microdosimetric quantities of interest in the same energy range; however, the averages calculated in this study are larger by about 15%compared to a TEPC filled with propane-based TE gas probably because of the larger stopping power of protons in propane compared to TE gas. These somewhat larger event sizes did not result in any significant increase in the Q-compared to those obtained from a TEPC filled with TE gas and were found to be in good agreement with other measurements reported earlier at corresponding neutron energies. The instrument quality factor response, R(Q), defined as the ratio of measured quality factor to the calculated quality factor in an ICRU tissue sphere,was found to vary with neutron energy. The instrument response,R(Q), was ~0.6 at 727 keV, which deteriorates further to

  14. Impacts of Parameters Adjustment of Relativistic Mean Field Model on Neutron Star Properties

    Science.gov (United States)

    Kasmudin; Sulaksono, A.

    Analysis of the parameters adjustment effects in isovector as well as in isoscalar sectors of effective field based relativistic mean field (E-RMF) model in the symmetric nuclear matter and neutron-rich matter properties has been performed. The impacts of the adjustment on slowly rotating neutron star are systematically investigated. It is found that the mass-radius relation obtained from adjusted parameter set G2** is compatible not only with neutron stars masses from 4U 0614+09 and 4U 1636-536, but also with the ones from thermal radiation measurement in RX J1856 and with the radius range of canonical neutron star of X7 in 47 Tuc, respectively. It is also found that the moment inertia of PSR J073-3039A and the strain amplitude of gravitational wave at the Earth's vicinity of PSR J0437-4715 as predicted by the E-RMF parameter sets used are in reasonable agreement with the extracted constraints of these observations from isospin diffusion data.

  15. Big Black Hole, Little Neutron Star: Magnetic Dipole Fields in the Rindler Spacetime

    CERN Document Server

    D'Orazio, Daniel J

    2013-01-01

    As a black hole and neutron star approach during inspiral, the field lines of a magnetized neutron star eventually thread the black hole event horizon and a short-lived electromagnetic circuit is established. The black hole acts as a battery that provides power to the circuit, thereby lighting up the pair just before merger. Although originally suggested as a promising electromagnetic counterpart to gravitational-wave detection, the luminous signals are promising more generally as potentially detectable phenomena, such as short gamma-ray bursts. To aid in the theoretical understanding, we present a analytic solutions for the electromagnetic fields of a magnetic dipole in the presence of an event horizon. In the limit that the neutron star is very close to a Schwarzschild horizon, the Rindler limit, we can solve Maxwell's equations exactly for a magnetic dipole on an arbitrary worldline. We present these solutions here and investigate a proxy for a small segment of the neutron star orbit around a big black hol...

  16. Field calibration of PADC track etch detectors for local neutron dosimetry in man using different radiation qualities

    Energy Technology Data Exchange (ETDEWEB)

    Haelg, Roger A., E-mail: rhaelg@phys.ethz.ch [Institute for Radiotherapy, Radiotherapie Hirslanden AG, Hirslanden Medical Center, Rain 34, CH-5000 Aarau (Switzerland); Besserer, Juergen [Institute for Radiotherapy, Radiotherapie Hirslanden AG, Hirslanden Medical Center, Rain 34, CH-5000 Aarau (Switzerland); Boschung, Markus; Mayer, Sabine [Division for Radiation Safety and Security, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Clasie, Benjamin [Department of Radiation Oncology, Massachusetts General Hospital, 30 Fruit Street, Boston, MA 02114 (United States); Kry, Stephen F. [Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 (United States); Schneider, Uwe [Institute for Radiotherapy, Radiotherapie Hirslanden AG, Hirslanden Medical Center, Rain 34, CH-5000 Aarau (Switzerland); Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 204, CH-8057 Zurich (Switzerland)

    2012-12-01

    In order to quantify the dose from neutrons to a patient for contemporary radiation treatment techniques, measurements inside phantoms, representing the patient, are necessary. Published reports on neutron dose measurements cover measurements performed free in air or on the surface of phantoms and the doses are expressed in terms of personal dose equivalent or ambient dose equivalent. This study focuses on measurements of local neutron doses inside a radiotherapy phantom and presents a field calibration procedure for PADC track etch detectors. An initial absolute calibration factor in terms of H{sub p}(10) for personal dosimetry is converted into neutron dose equivalent and additional calibration factors are derived to account for the spectral changes in the neutron fluence for different radiation therapy beam qualities and depths in the phantom. The neutron spectra used for the calculation of the calibration factors are determined in different depths by Monte Carlo simulations for the investigated radiation qualities. These spectra are used together with the energy dependent response function of the PADC detectors to account for the spectral changes in the neutron fluence. The resulting total calibration factors are 0.76 for a photon beam (in- and out-of-field), 1.00 (in-field) and 0.84 (out-of-field) for an active proton beam and 1.05 (in-field) and 0.91 (out-of-field) for a passive proton beam, respectively. The uncertainty for neutron dose measurements using this field calibration method is less than 40%. The extended calibration procedure presented in this work showed that it is possible to use PADC track etch detectors for measurements of local neutron dose equivalent inside anthropomorphic phantoms by accounting for spectral changes in the neutron fluence.

  17. Theory of the fission source driven neutron noise field

    International Nuclear Information System (INIS)

    The extensive use of the 252Cf driven noise technique makes it desirable to develop a general theory of the fission source driven noise field. For photoneutron sources and a point reactor model, a unified theory of the different experimental techniques used in noise analysis was developed by Pacilio. They used the probability generating function (PGF) as the common element of all the experimental techniques. Similarly, if the PGF is obtained in the presence of a fission source, the equations relevant to all the noise techniques using such a source can be obtained. A very detailed theory has been proposed recently in order to include the space and energy variables in the equations describing the stochastic field for both types of sources. The complications of the formalism restrict its practical applications to the calculation of the first moments of the distribution of counts instead of the calculation of the PGF. Consequently it seems convenient to explore the possibility of obtaining the entire PGF with a simpler model

  18. Neutron spin echo spectroscopy under 17 T magnetic field at RESEDA

    Directory of Open Access Journals (Sweden)

    Kindervater J.

    2015-01-01

    Full Text Available We report proof-of-principle measurements at the neutron resonance spin echo spectrometer RESEDA (MLZ under large magnetic fields by means of Modulation of IntEnsity with Zero Effort (MIEZE. Our study demonstrates the feasibility of applying strong magnetic fields up to 17 T at the sample while maintaining unchanged sub-μeV resolution. We find that the MIEZE-spin-echo resolution curve remains essentially unchanged as a function of magnetic field up to the highest fields available, promising access to high fields without need for additional fine-tuning of the instrument. This sets the stage for the experimental investigations of subtle field dependent phenomena, such as magnetic field-driven phase transitions in hard and soft condensed matter physics.

  19. Particle discrimination of NaI(Tl) scintillator under high-energy neutron field to measure the photon energy spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Kamada, So, E-mail: kamada-s@nmri.go.jp; Takada, Masashi; Suzuki, Toshikazu

    2014-09-11

    Photons are measured separately from neutrons in high-energy neutron fields using a NaI(Tl) scintillator, 7.62 cm in diameter and 7.62 cm in length, combined with a pulse-shape discrimination method. The particle discrimination capability for this scintillator is confirmed using a time-of-flight method. Neutron fields were produced by irradiating Li targets with 40 and 80 MeV proton beams at the cyclotron facility in the National Institute of Radiological Sciences. Figures of merit corresponding to particle discrimination for the scintillator at the two neutron fields are improved with higher neutron energies. Photon energy spectra for energies over 6.5 MeV can be measured using the NaI(Tl) scintillator.

  20. R-modes of a neutron star with a magnetic dipole field

    CERN Document Server

    Lee, U

    2004-01-01

    We study $r$-modes of a rotating magnetized neutron star, assuming a magnetic dipole field whose axis is aligned with the axis of rotation. We approach the problem by applying a singular perturbation theory to the oscillations of rotating stars. In this treatment, we divide the star into a thin surface magnetic layer and a non-magnetic core. We integrate linearized ideal MHD equations in the surface magnetic layer and non-magnetic oscillation equations in the core, and match the two integrations at the interface to obtain a complete solution. For a polytropic neutron star model of mass $M=1.4M_\\odot$ and radius $R=10^6$cm, the magnetic dipole field becomes effective on the modal properties of the $r$-modes only when the field strength $B_S$ is much greater than $10^{14}$G. We also find that the damping effects caused by very short magnetic perturbations in the surface layer are not important for the $r$-mode instability of rapidly rotating neutron stars if the field strength $B_S$ is smaller than $10^{12}$G.

  1. Biological determination of the variation of fast-neutron field quality with depth, RBE, and OER

    International Nuclear Information System (INIS)

    The biological effectiveness of two cyclotron-produced fast neutron fields (E/sub n/ approximately 3.5 and 7 MeV) has been studied as a function of depth within a water phantom. Aerobic and hypoxic HeLa S3 cell survival data were obtained at depths of 2 and 12 cm and compared with those measured in a 60Co gamma ray field. Although the resulting survival curves show a small decrease in sensitivity with increasing depth, the oxygen enhancement ratio remains constant and has a value of 1.8 +- 0.1 in both fields. (U.S.)

  2. Development and characteristics of the HANARO ex-core neutron irradiation facility for applications in the boron neutron capture therapy field

    CERN Document Server

    Kim, M S; Jun, B J; Kim, H; Lee, B C; Hwang, Sung-Yul; Jun, Byung-Jin; Kim, Heonil; Kim, Myong-Seop; Lee, Byung-Chul

    2006-01-01

    The HANARO ex-core neutron irradiation facility was developed for various applications in the boron neutron capture therapy (BNCT) field, and its characteristics have been investigated. In order to obtain a sufficient thermal neutron flux with a low level contamination of fast neutrons and gamma-rays, a radiation filtering method is adopted. The radiation filter has been designed by using a silicon single crystal cooled by liquid nitrogen and a bismuth crystal. The installation of the main components of the irradiation facility and the irradiation room are finished. Experimental measurements of the neutron beam characteristics have been performed by using bare and cadmium covered gold foils and wires. The in-phantom neutron flux distribution was measured for a flux mapping inside the phantom. The gamma-ray dose was determined by using TLD-700 thermoluminescence dosimeters. The thermal and fast neutron fluxes and the gamma-ray dose were calculated by using the MCNP code, and they were compared with experimenta...

  3. Validation of updated neutronic calculation models proposed for Atucha-II PHWR. Part II: Benchmark comparisons of PUMA core parameters with MCNP5 and improvements due to a simple cell heterogeneity correction

    International Nuclear Information System (INIS)

    In 2005 the Argentine Government took the decision to complete the construction of the Atucha-II nuclear power plant, which has been progressing slowly during the last ten years. Atucha-II is a 745 MWe nuclear station moderated and cooled with heavy water, of German (Siemens) design located in Argentina. It has a pressure vessel design with 451 vertical coolant channels and the fuel assemblies (FA) are clusters of 37 natural UO2 rods with an active length of 530 cm. For the reactor physics area, a revision and update of reactor physics calculation methods and models was recently carried out covering cell, supercell (control rod) and core calculations. This paper presents benchmark comparisons of core parameters of a slightly idealized model of the Atucha-I core obtained with the PUMA reactor code with MCNP5. The Atucha-I core was selected because it is smaller, similar from a neutronic point of view, more symmetric than Atucha-II, and has some experimental data available. To validate the new models benchmark comparisons of k-effective, channel power and axial power distributions obtained with PUMA and MCNP5 have been performed. In addition, a simple cell heterogeneity correction recently introduced in PUMA is presented, which improves significantly the agreement of calculated channel powers with MCNP5. To complete the validation, the calculation of some of the critical configurations of the Atucha-I reactor measured during the experiments performed at first criticality is also presented. (authors)

  4. Status of the international criticality safety benchmark evaluation project (ICSBEP)

    International Nuclear Information System (INIS)

    Since ICNC'99, four new editions of the International Handbook of Evaluated Criticality Safety Benchmark Experiments have been published. The number of benchmark specifications in the Handbook has grown from 2157 in 1999 to 3073 in 2003, an increase of nearly 1000 specifications. These benchmarks are used to validate neutronics codes and nuclear cross-section data. Twenty evaluations representing 192 benchmark specifications were added to the Handbook in 2003. The status of the International Criticality Safety Benchmark Evaluation Project (ICSBEP) is provided in this paper along with a summary of the newly added benchmark specifications that appear in the 2003 Edition of the Handbook. (author)

  5. Description of a neutron field perturbed by a probe using coupled Monte Carlo and discrete ordinates radiation transport calculations

    International Nuclear Information System (INIS)

    This work concerns calculation of a neutron response, caused by a neutron field perturbed by materials surrounding the source or the detector. Solution of a problem is obtained using coupling of the Monte Carlo radiation transport computation for the perturbed region and the discrete ordinates transport computation for the unperturbed system. (author). 62 refs

  6. Use of a spherical albedo system for correcting the readings of albedo dosimeters in JINR phasotron neutron radiation fields

    Science.gov (United States)

    Mokrov, Yu. V.; Morozova, S. V.

    2014-03-01

    Results of calibrating a spherical albedo system in the radiation fields of a Pu-Be radionuclide neutron source are presented. It is shown that it can be used for correcting the readings of the DVGN-01 albedo dosimeter. The results of measurements with the system in JINR phasotron neutron fields for the purpose of correcting the DVGN-01 readings in these fields are given. The values of the correction factors for DVGN-01 albedo dosimeters when used in personnel neutron dosimetry (PD) on the JINR phasotron are determined.

  7. Spectra of photons and neutrons generated in a heterogeneous head of a 15 MV LINAC at differents field sizes

    Energy Technology Data Exchange (ETDEWEB)

    Benites-Rengifo, J. L.; Vega-Carrillo, H. R.; Velazquez-Fernandez, J. B. [Posgrado en CBAP, Universidad Autonoma de Nayarit, Carretera Tepic-Compostela km 9. C.P. 63780. Xalisco, Nayarit (Mexico); Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Apdo. Postal 336, 98000 Zacatecas, Zac. (Mexico); Posgrado en CBAP, Universidad Autonoma de Nayarit, Carretera Tepic-Compostela km 9. C.P. 63780. Xalisco, Nayarit (Mexico)

    2012-10-23

    Spectra of photons and neutrons were calculated, using the Monte Carlo code MCNP-5 using the e/p/n mode. A heterogeneous model was used to define the linac head where the collimators were modeled to produce five different treatment fields at the isocenter. Photon and neutron spectra were estimated in several points along two directions from the isocenter. The total photon fluence beyond 60 cm behaves according to 1/r{sup 2} rule, while total neutron fluence, beyond 80 cm, can be described by diffusion theory using an infinite plane as a neutron source.

  8. Magnetic field amplification in hypermassive neutron stars via the magnetorotational instability

    CERN Document Server

    Siegel, Daniel M

    2014-01-01

    Mergers of binary neutron stars likely lead to the formation of a hypermassive neutron star (HMNS), which is metastable and eventually collapses to a black hole. This merger scenario is thought to explain the phenomenology of short gamma-ray bursts (SGRBs). The very high energies observed in SGRBs have been suggested to stem from neutrino-antineutrino annihilation and/or from very strong magnetic fields created during or after the merger by mechanisms like the magnetorotational instability (MRI). Here, we report on results that show for the first time the development of the MRI in HMNSs in three-dimensional, fully general-relativistic magnetohydrodynamic simulations. This instability amplifies magnetic fields exponentially and could be a vital ingredient in solving the SGRB puzzle.

  9. Hydrogen Concentration and Strain Fields Near Fatigue Cracks in Pipeline Steel Measured Via Neutron Imaging

    Science.gov (United States)

    Connolly, Matthew; Slifka, Andrew; Drexler, Elizabeth; Hydrogen Pipeline Safety Team

    Hydrogen (H2) is desirable for energy storage as it is cleaner burning and can store a larger amount of energy than an equal mass of gasoline. One problem in the development of a hydrogen economy is to find or develop materials that ensure the safe, reliable, and cost-effective flow of energy from the source to the user. It is expected steels will be needed to serve this function. However, the existing network of natural gas pipeline, for example, is constructed of ferrous materials which are susceptible to embrittlement and subsequent increased fatigue crack growth rates after exposure to hydrogen. In order to improve current modeling efforts, experimental determination of hydrogen concentration, hydrogen diffusion rates, and strain fields are required to inform and validate the model. Here we report neutron imaging measurements of the hydrogen concentration near a fatigue crack and the corresponding strain field, measured via neutron transmission Bragg edge spectroscopy. Nist Materials Measurement Laboratory, Applied Chemicals and Materials Division.

  10. Recent developments in neutron-proton scattering with Lattice Effective Field Theory

    CERN Document Server

    Alarcón, Jose Manuel

    2015-01-01

    In this contribution, we show some recent progress in the study of neutron-proton scattering with Nuclear Lattice Effective Field Theory (NLEFT). We present preliminary studies of both, the uncertainties in the $np$ phase shifts extracted with NLEFT, and the lattice spacing dependence in the transfer matrix formalism. Such investigations have not been performed before in the literature, and will be relevant for Monte Carlo simulations of nuclear structure with NLEFT.

  11. The cross-section data from neutron activation experiments on niobium in the NPI p-7Li quasi-monoenergetic neutron field

    Science.gov (United States)

    Honusek, M.; Bém, P.; Fischer, U.; Götz, M.; Novák, J.; Simakov, S. P.; Šimečková, E.

    2010-10-01

    The reaction of protons on 7Li target produces the high-energy quasi- monoenergetic neutron spectrum with the tail to lower energies. Proton energies of 19.8, 25.1, 27.6, 30.1, 32.6, 35.0 and 37.4 MeV were used to obtain quasi-monoenergetic neutrons with energies of 18, 21.6, 24.8, 27.6, 30.3, 32.9 and 35.6 MeV, respectively. Nb cross-section data for neutron energies higher than 22.5 MeV do not exist in the literature. Nb is the important material for fusion applications (IFMIF) as well. The variable-energy proton beam of NPI cyclotron is utilized for the production of neutron field using thin lithium target. The carbon backing serves as the beam stopper. The system permits to produce neutron flux density about 109 n/cm2/s in peak at 30 MeV neutron energy. The niobium foils of 15 mm in diameter and approx. 0.75 g weight were activated. The nuclear spectroscopy methods with HPGe detector technique were used to obtain the activities of produced isotopes. The large set of neutron energies used in the experiment allows us to make the complex study of the cross-section values. The reactions (n,2n), (n,3n), (n,4n), (n,He3), (n,α) and (n,2nα) are studied. The cross-sections data of the (n,4n) and (n,2nα) are obtained for the first time. The cross-sections of (n,2n) and (n,α) reactions for higher neutron energies are strongly influenced by low energy tail of neutron spectra. This effect is discussed. The results are compared with the EAF-2007 library.

  12. The cross-section data from neutron activation experiments on niobium in the NPI p-7Li quasi-monoenergetic neutron field

    Directory of Open Access Journals (Sweden)

    Simakov S.P.

    2010-10-01

    Full Text Available The reaction of protons on 7Li target produces the high-energy quasi- monoenergetic neutron spectrum with the tail to lower energies. Proton energies of 19.8, 25.1, 27.6, 30.1, 32.6, 35.0 and 37.4 MeV were used to obtain quasi-monoenergetic neutrons with energies of 18, 21.6, 24.8, 27.6, 30.3, 32.9 and 35.6 MeV, respectively. Nb cross-section data for neutron energies higher than 22.5 MeV do not exist in the literature. Nb is the important material for fusion applications (IFMIF as well. The variable-energy proton beam of NPI cyclotron is utilized for the production of neutron field using thin lithium target. The carbon backing serves as the beam stopper. The system permits to produce neutron flux density about 109  n/cm2/s in peak at 30 MeV neutron energy. The niobium foils of 15 mm in diameter and approx. 0.75 g weight were activated. The nuclear spectroscopy methods with HPGe detector technique were used to obtain the activities of produced isotopes. The large set of neutron energies used in the experiment allows us to make the complex study of the cross-section values. The reactions (n,2n, (n,3n, (n,4n, (n,He3, (n,α and (n,2nα are studied. The cross-sections data of the (n,4n and (n,2nα are obtained for the first time. The cross-sections of (n,2n and (n,α reactions for higher neutron energies are strongly influenced by low energy tail of neutron spectra. This effect is discussed. The results are compared with the EAF-2007 library.

  13. Applying full multigroup cell characteristics from MCU code to finite difference calculations of neutron field in VVER core

    Energy Technology Data Exchange (ETDEWEB)

    Gorodkov, S.S.; Kalugin, M.A. [Nuclear Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation)

    2015-09-15

    Up to now core calculations with Monte Carlo provided only average cross-sections of mesh cells for further use either in finite difference calculations or as benchmark ones for approximate spectral algorithms. Now MCU code is capable to handle functions, which may be interpreted as average diffusion coefficients. Subsequently the results of finite difference calculations with cells characteristic sets obtained in such a way can be compared with Monte Carlo results as benchmarks, giving reliable information on quality of production code under consideration. As an example of such analysis, the results of mesh calculations with 1-, 2-, 4-, 8- and 12 neutron groups of some model VVER fuel assembly are presented in comparison with the exact Monte Carlo solution. As a second example, an analysis is presented of water gap approximate enlargement between fuel assemblies, allowing VVER core region be covered by regular mesh.

  14. Effects of neutrino emissivity on the cooling of neutron stars in the presence of a strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, Eduardo Lenho, E-mail: eduardo.coelho@uva.br [Universidade Veiga de Almeida, 108 Ibituruna St., 20271-020, Rio de Janeiro (Brazil); Chiapparini, Marcelo [Instituto de Física, Universidade do Estado do Rio de Janeiro, 524 São Francisco Xavier St., 20271-020, Rio de Janeiro (Brazil); Negreiros, Rodrigo Picanço [Instituto de Física, Universidade Federal Fluminense, Gal. Milton Tavares de Souza Ave., 24210-346, Rio de Janeiro (Brazil)

    2015-12-17

    One of the most interesting kind of neutron stars are the pulsars, which are highly magnetized neutron stars with fields up to 10{sup 14} G at the surface. The strength of magnetic field in the center of a neutron star remains unknown. According to the scalar virial theorem, magnetic field in the core could be as large as 10{sup 18} G. In this work we study the influence of strong magnetic fields on the cooling of neutron stars coming from direct Urca process. Direct Urca process is an extremely efficient mechanism for cooling a neutron star after its formation. The matter is described using a relativistic mean-field model at zero temperature with eight baryons (baryon octet), electrons and muons. We obtain the relative population of each species of particles as function of baryon density for different magnetic fields. We calculate numerically the cooling of neutron stars for a parametrized magnetic field and compare the results for the case without a magnetic field.

  15. Metric of the gravitational field outside the neutron star

    Institute of Scientific and Technical Information of China (English)

    WANG; Yongjiu

    2001-01-01

    [1]Vogeley, M. S., Szalay, A. S., Eigenmode analysis of galaxy redsh ift surveys. I. theory and methods, ApJ, 1996, 465: 34-53.[2]Fang, L. Z., Pando, J., Large-scale structures revealed by wavel et decomposition, The 5th Current Topics of Astrofundamental Physics (eds. Sanch ez, N., Zichichi, A.), Singapore: World Scientific, 1997.[3]Pando, J., Fang, L. Z., Detecting the non-Gaussian spectrum of Q SO's Lyalpha absorption line distribution, A&A, 1998, 340: 335-342.[4]Xu, W., Fang, L. Z., Deng, Z. G., Scale invariance of rich cluste r abundance: A possible test for models of structure formation, ApJ, 1998, 508: 472-482.[5]Pando, J., Valls-Gabaud, D., Fang, L. Z., Evidence for scale-sc ale correlations in the cosmic microwave background radiation, PRL, 1998, 81: 45 68-4571.[6]Feng, L. L., Fang, L. Z., Non-Gaussianity and the recovery of th e mass power spectrum from the Lyα forest, ApJ, 2000, 535: 519-529.[7]Feng, L. L., Deng, Z. G., Fang, L. Z., Breaking degeneracy of dar k matter models by the scale-scale correlations of galaxies, ApJ, 2000, 530: 53 -61.[8]Fang, L. Z., Feng, L. L., Measuring the galaxy power spectrum and scale-scale correlations with multiresolution-decomposed covariance-I. metho d, ApJ, 2000, 539: 9-22.[9]Tegmark, M., Hamilton, A. J. S., Vogeley, M. S. et al., Measuring the galaxy power spectrum with future redshift surveys, ApJ, 1998, 499: 555-57 6.[10]Bardeen, J. M., Bond, J. R., Kaiser, N. et al., The statistics of peak s of Gauss random fields, ApJ, 1986, 304: 15-61.[11]Peacock, J. A., Dodds, S. J., Linear power spectrum of cosmological ma ss fluctuations, MNRAS, 1994, 267: 1020-1034.[12]White, S. D. M., Efstathiou, G., Frenk, C. S., The amplitude of mass f luctuations in the universe, MNRAS, 1993, 262: 1023-1028.[13]Peacock, J. A., Dodds, S. J., Non-linear evolution of cosmological po wer spectra, MNRAS, 1996, 280: L19-L26.[14]Loveday, J., Peterson, B. A., Efstathiou, G. et al., The

  16. Sensitivity Reach of the Neutron EDM Experiment: The Electric Field Strength

    Science.gov (United States)

    Hennings-Yeomans, R.; Cooper, M.; Currie, S. A.; Makela, M. F.; Ramsey, J. C.; Tajima, S.; Womack, T. L.; Long, J. C.; Stanislaus, S.

    2010-08-01

    The search for an electric dipole moment of the neutron tests physics beyond the Standard Model such as new sources of CP-violation and Supersymmetry. The nEDM experiment aims to improve the sensitivity on the current limit of the electric dipole moment of the neutron to EDM when an electric field is applied parallel and antiparallel to a magnetic field across the neutron storage cell. A dominant parameter in terms of reducing the statistical uncertainty of this measurement is the strength of the applied electric field. An experiment to measure if superfluid He-II can sustain up to 50 kV/cm for a volume and electrode spacings comparable to the nEDM experiment has been constructed at Los Alamos National Laboratory. It consists in a large-area parallel plate capacitor immersed in a 200 liter central volume inside a suitable cryostat that in turn is connected to a dilution refrigerator unit. A description of test runs and the status of the experiment is presented.

  17. Interior Vector Magnetic Field Monitoring for the SNS Neutron EDM Experiment

    Science.gov (United States)

    Nouri, Nima; Plaster, Brad

    2014-09-01

    A concept has been developed which provides for a real-time determination of the spatial dependence of the vector components of the magnetic field (and, hence, the ∂Bi / ∂xj field gradients) within the interior fiducial volume of the SNS neutron EDM experiment solely from exterior measurements at fixed discrete locations. This technique will be especially important during the operation of the experiment, when direct measurements of the field gradients present within the fiducial volume will not be physically possible. Our method, which is based on the solution to the Laplace Equation, is completely general and does not require the field to possess any type of symmetry. We describe the concept and our systematic approach for optimizing the locations of these exterior measurements. We also present results from prototyping studies of a field monitoring system deployed within a half-scale prototype of the experiment's magnetic field environment. A concept has been developed which provides for a real-time determination of the spatial dependence of the vector components of the magnetic field (and, hence, the ∂Bi / ∂xj field gradients) within the interior fiducial volume of the SNS neutron EDM experiment solely from exterior measurements at fixed discrete locations. This technique will be especially important during the operation of the experiment, when direct measurements of the field gradients present within the fiducial volume will not be physically possible. Our method, which is based on the solution to the Laplace Equation, is completely general and does not require the field to possess any type of symmetry. We describe the concept and our systematic approach for optimizing the locations of these exterior measurements. We also present results from prototyping studies of a field monitoring system deployed within a half-scale prototype of the experiment's magnetic field environment. This work was supported in part by the U.S. Department of Energy Office of

  18. KIC 1571511B: A Benchmark Low-Mass Star In An Eclipsing Binary System In The Kepler Field

    CERN Document Server

    Ofir, Aviv; Buchhave, Lars; Lacy, Claud H S; Hatzes, Artie P; Fridlund, Malcolm

    2011-01-01

    KIC 1571511 is a 14d eclipsing binary (EB) in the Kepler dataset. The secondary of this EB is a very low mass star with a mass of 0.14136 +/- 0.00036 M_sun and a radius of 0.17831 +0.00051/-0.00062 R_sun (statistical errors only). The overall system parameters make KIC 1571511B an ideal "benchmark object": among the smallest, lightest and best-described stars known, smaller even than some known exoplanet. Currently available photometry encompasses only a small part of the total: future Kepler data releases promise to constrain many of the properties of KIC 1571511B to unprecedented level. However, as in many spectroscopic single-lined systems, the current error budget is dominated by the modeling errors of the primary and not by the above statistical errors. We conclude that detecting the RV signal of the secondary component is crucial to achieving the full potential of this possible benchmark object for the study of low mass stars.

  19. Optimal design of measurement network for neutronic activity field reconstruction by data assimilation

    International Nuclear Information System (INIS)

    Data assimilation methods, that merge information from model and measurement, can be used to obtain an optimal determination of neutronic activity field within a nuclear reactor core. Here the problem is to determine an optimal spatial distribution of the instruments, within the core, to get the best possible field reconstruction from data assimilation procedure. The position optimization is based on simulated annealing with a Metropolis- Hasting algorithm. To perform the method in the framework of data assimilation, several algebraic optimization for computing time of data assimilation has been developed and are presented here. (authors)

  20. Optimal design of measurement network for neutronic activity field reconstruction by data assimilation

    International Nuclear Information System (INIS)

    Several studies show that data assimilation methods, by merging information both from model and measurement can be used to elaborate an optimal determination of neutronic activity field within a nuclear PWR reactor core. Here the problem addressed and solved is to determine an optimal repartition of the instruments, used to make measurements within the core, to get the best possible reconstructed field using a data assimilation procedure. The position optimization is based on simulated annealing, with a Metropolis-Hasting algorithm. To perform the method in the framework of data assimilation, algebraic optimisation related to computing time of data assimilation has been developed and is used here. (author)

  1. General relativistic simulations of black hole-neutron star mergers: Effects of tilted magnetic fields

    OpenAIRE

    Etienne, Zachariah B.; Paschalidis, Vasileios; Shapiro, Stuart L.

    2012-01-01

    Black hole--neutron star (BHNS) binary mergers can form disks in which magnetorotational instability (MRI)-induced turbulence may drive accretion onto the remnant BH, supporting relativistic jets and providing the engine for a short-hard gamma-ray burst (SGRB). Our earlier study of magnetized BHNSs showed that NS tidal disruption winds the magnetic field into a toroidal configuration, with poloidal fields so weak that capturing MRI with full-disk simulations would require $\\sim 10^8$ CPU-hour...

  2. Optimal design of measurement network for neutronic activity field reconstruction by data assimilation

    International Nuclear Information System (INIS)

    Several studies show that data assimilation methods, by merging information both from model and measurement, can be used to elaborate an optimal determination of neutronic activity field within a nuclear PWR reactor core. Here the problem addressed and solved is to determine an optimal repartition of the instruments within the core, to get the best possible reconstructed field using a data assimilation procedure. The position optimization is based on simulated annealing with a Metropolis-Hasting algorithm. To perform the method in the framework of data assimilation, several algebraic optimisation related to computing time of data assimilation has been developed and are presented here. (author)

  3. Neutron Fermi Liquids under the presence of a strong magnetic field with effective nuclear forces

    CERN Document Server

    Perez-Garcia, M Angeles; Polls, A

    2009-01-01

    Landau's Fermi Liquid parameters are calculated for non-superfluid pure neutron matter in the presence of a strong magnetic field at zero temperature. The particle-hole interactions in the system, where a net magnetization may be present, are characterized by these parameters in the framework of a multipolar formalism. We use either zero- or finite-range effective nuclear forces to describe the nuclear interaction. Using the obtained Fermi Liquid parameters, the effect of a strong magnetic field on some bulk magnitudes such as isothermal compressibility and spin susceptibility is also investigated.

  4. Neutron scattering studies of crude oil viscosity reduction with electric field

    Science.gov (United States)

    Du, Enpeng

    topic. Dr. Tao with his group at Temple University, using his electro or magnetic rheological viscosity theory has developed a new technology, which utilizes electric or magnetic fields to change the rheology of complex fluids to reduce the viscosity, while keeping the temperature unchanged. After we successfully reduced the viscosity of crude oil with field and investigated the microstructure changing in various crude oil samples with SANS, we have continued to reduce the viscosity of heavy crude oil, bunker diesel, ultra low sulfur diesel, bio-diesel and crude oil and ultra low temperature with electric field treatment. Our research group developed the viscosity electrorheology theory and investigated flow rate with laboratory and field pipeline. But we never visualize this aggregation. The small angle neutron scattering experiment has confirmed the theoretical prediction that a strong electric field induces the suspended nano-particles inside crude oil to aggregate into short chains along the field direction. This aggregation breaks the symmetry, making the viscosity anisotropic: along the field direction, the viscosity is significantly reduced. The experiment enables us to determine the induced chain size and shape, verifies that the electric field works for all kinds of crude oils, paraffin-based, asphalt-based, and mix-based. The basic physics of such field induced viscosity reduction is applicable to all kinds of suspensions.

  5. Novel recoil nuclei detectors to qualify the AMANDE facility as a Standard for mono-energetic neutron fields

    OpenAIRE

    Allaoua, A.; Guillaudin, O.; Higueret, S.; Husson, D.; Lebreton, L.; Mayet, F.; Nourreddine, M.; Santos, D.; Trichet, A.

    2008-01-01

    The AMANDE facility at IRSN-Cadarache produces mono-energetic neutron fields from 2 keV to 20 MeV with metrological quality. To be considered as a standard facility, characteristics of neutron field i.e fluence distribution must be well known by a device using absolute measurements. The development of new detector systems allowing a direct measurement of neutron energy and fluence has started in 2006. Using the proton recoil telescope principle with the goal of increase the efficiency, two sy...

  6. Measurements of the high energy neutron component of cosmic radiation fields in aircraft using etched track dosemeters

    CERN Document Server

    Bartlett, D T; Tanner, R J; Steele, J D

    2001-01-01

    Measurements of the complex cosmic radiation field in aircraft at altitude are made with a passive survey meter comprising routine-use thermoluminescent detectors and etched track detectors. The energy dependence of response of the etched track detectors used to determine the neutron component has been characterized, partly, up to a neutron energy of 180 MeV. The neutron detectors are routinely calibrated in the CERN EC Ref.Field. The 15% determination level for total dose equivalent is 100 mu Sv. The evidence is that the passive survey meter provides a reliable determination of route dose. (41 refs).

  7. Cooling of neutron stars and emissivity of neutrinos by the direct Urca process under influence of a strong magnetic field

    Science.gov (United States)

    Coelho, E. L.; Chiapparini, M.; Negreiros, R. P.

    2016-04-01

    Neutron stars are born with high temperatures and during a few seconds suffer rapid cooling by emission of neutrinos. The direct Urca process is the main mechanism to explain this loss of energy. In this work we study the influence of a strong magnetic field on the composition of nuclear matter at high densities and zero temperature. We describe the matter through a relativistic mean-field model with eight light baryons (baryon octet), electrons, muons magnetic field. As output of the numerical calculations, we obtain the relative population for a parametrized magnetic field. We calculate the cooling of neutron stars with different mass and magnetic fields due to direct Urca process.

  8. Multipolar electromagnetic fields around neutron stars: exact vacuum solutions and related properties

    CERN Document Server

    Petri, Jerome

    2015-01-01

    The magnetic field topology in the surrounding of neutron stars is one of the key questions in pulsar magnetospheric physics. A very extensive literature exists about the assumption of a dipolar magnetic field but very little progress has been made in attempts to include multipolar components in a self-consistent way. In this paper, we study the effect of multipolar electromagnetic fields anchored in the star. We give exact analytical solutions in closed form for any order $l$ and apply them to the retarded point quadrupole ($l=2$), hexapole ($l=3$) and octopole ($l=4$), a generalization of the retarded point dipole ($l=1$). We also compare the Poynting flux from each multipole and show that the spin down luminosity depends on the ratio $R/r_{\\rm L}$, $R$ being the neutron star radius and $r_{\\rm L}$ the light-cylinder radius. Therefore the braking index also depends on $R/r_{\\rm L}$. As such multipole fields possess very different topology, most importantly smaller length scales compared to the dipolar field...

  9. Surface temperature of a magnetized neutron star and interpretation of the ROSAT data. 1: Dipole fields

    Science.gov (United States)

    Page, Dany

    1995-01-01

    We model the temperature distribution at the surface of a magnetized neutron star and study the effects on the observed X-ray spectra and light curves. Generalrelativistic effects, i.e., redshift and lensing, are fully taken into account. Atmospheric effects on the emitted spectral flux are not included: we consider only blackbody emission at the local effective temperature. In this first paper we restrict ourselves to dipole fields. General features are studied and compared with the ROSAT data from the pulsars 0833 - 45 (Vela), 0656 + 14, 0630 + 178 (Geminga), and 1055 - 52, the four cases for which there is strong evidence that thermal radiation from the stellar surface is detected. The composite spectra we obtain are not very different from a blackbody spectrum at the star's effective temperature. We conclude that, as far as blackbody spectra are considered, temperature estimates using single-temperature models give results practically identical to our composite models. The change of the (composite blackbody) spectrum with the star's rotational phase is also not very large and may be unobservable inmost cases. Gravitational lensing strongly suppresses the light curve pulsations. If a dipole field is assumed, pulsed fractions comparable to the observed ones can be obtained only with stellar radii larger than those which are predicted by current models of neutron star struture, or with low stellar masses. Moreover, the shapes of the theoretical light curves with dipole fields do not correspond to the observations. The use of magnetic spectra may raise the pulsed fraction sufficiently but will certainly make the discrepancy with the light curve shapes worse: dipole fields are not sufficient to interpret the data. Many neutron star models with a meson condensate or hypersons predict very small radii, and hence very strong lensing, which will require highly nondipolar fields to be able to reproduce the observed pulsed fractions, if possible at all: this may be a new

  10. Benchmarking of Decay Heat Measured Values of ITER Materials Induced by 14 MeV Neutron Activation with Calculated Results by ACAB Activation Code

    Energy Technology Data Exchange (ETDEWEB)

    Tore, C.; Ortego, P.; Rodriguez Rivada, A.

    2014-07-01

    The aim of this paper is the comparison between the calculated and measured decay heat of material samples which were irradiated at the Fusion Neutron Source of JAERI in Japan with D-T production of 14MeV neutrons. In the International Thermonuclear Experimental Reactor (ITER) neutron activation of the structural material will result in a source of heat after shutdown of the reactor. The estimation of decay heat value with qualified codes and nuclear data is an important parameter for the safety analyses of fusion reactors against lost of coolant accidents. When a loss of coolant and/or flow accident happen plasma facing components are heated up by decay heat. If the temperature of the components exceeds the allowable temperature, the accident would expand to loose the integrity of ITER. Uncertainties associated with decay prediction less than 15% are strongly requested by the ITER designers. Additionally, accurate decay heat prediction is required for making reasonable shutdown scenarios of ITER. (Author)

  11. Antikaons in neutron star studied with recent versions of relativistic mean-field models

    Science.gov (United States)

    Gupta, Neha; Arumugam, P.

    2013-03-01

    We study the impact of additional couplings in the relativistic mean field (RMF) models, in conjunction with antikaon condensation, on various neutron star properties. We analyze different properties such as in-medium antikaon and nucleon effective masses, antikaon energies, chemical potentials and the mass-radius relations of neutron star (NS). We calculate the NS properties with the RMF (NL3), E-RMF (G1, G2) and FSU2.1 models, which are quite successful in explaining several finite nuclear properties. Our results show that the onset of kaon condensation in NS strongly depends on the parameters of the Lagrangian, especially the additional couplings which play a significant role at higher densities where antikaons dominate the behavior of equation of state.

  12. Antikaons in neutron star studied with recent versions of relativistic mean-field models

    CERN Document Server

    Gupta, Neha

    2013-01-01

    We study the impact of additional couplings in the relativistic mean field (RMF) models, in conjunction with antikaon condensation, on various neutron star properties. We analyze different properties such as in-medium antikaon and nucleon effective masses, antikaon energies, chemical potentials and the mass-radius relations of neutron star (NS). We calculate the NS properties with the RMF (NL3), E-RMF (G1, G2) and FSU2.1 models, which are quite successful in explaining several finite nuclear properties. Our results show that the onset of kaon condensation in NS strongly depends on the parameters of the Lagrangian, especially the additional couplings which play a significant role at higher densities where antikaons dominate the behavior of equation of state.

  13. Hyperons in neutron star matter within relativistic mean-field models

    CERN Document Server

    Oertel, M; Gulminelli, F; Raduta, A R

    2014-01-01

    Since the discovery of neutron stars with masses around 2 solar masses the composition of matter in the central part of these massive stars has been intensively discussed. Within this paper we will (re)investigate the question of the appearance of hyperons. To that end we will perform an extensive parameter study within relativistic mean field models. We will show that it is possible to obtain high mass neutron stars (i) with a substantial amount of hyperons, (ii) radii of 12-13 km for the canonical mass of 1.4 solar masses, and (iii) a spinodal instability at the onset of hyperons. The results depend strongly on the interaction in the hyperon-hyperon channels, on which only very little information is available from terrestrial experiments up to now.

  14. Magnetic domains in multiferroic YMn$2O5 probed by Spherical Neutron Polarimetry under electric field

    Science.gov (United States)

    Vecchini, Carlo; Chapon, Laurent; Radaelli, Paolo; Daoud-Aladine, Aziz; Brown, Jane; Chatterji, Tapan; Park, Soonyong; Cheong, Sang-Wook

    2008-03-01

    Precise determination of the magnetic structures in multiferroics RMn2O5 (R: Y, Ho, Bi) have been obtained by single crystal neutron diffraction. The analysis shows the presence of zig-zag antiferromagnetic chains in the ab-plane. An additional weak magnetic component parallel to the c-axis was detected which is modulated in phase quadrature with the a-b components. The nature and population of the coexisting antiferromagnetic domains in YMn2O5 have been determined by Spherical Neutron Polarimetry under an external electric field. We have proved that reversing the electrical polarity results in the inversion of the population of two types of antiferromagnetic domains, with opposite in-plane spin components. This analysis strongly supports theories in which the coupling of the magnetic configuration to the ferroelectric polarisation is due to magnetic exchange striction and likely not related to the small cycloidal modulation in the bc-plane.

  15. Disordered nuclear pasta, magnetic field decay, and crust cooling in neutron stars

    CERN Document Server

    Horowitz, C J; Briggs, C M; Caplan, M E; Cumming, A; Schneider, A S

    2014-01-01

    Nuclear pasta, with non-spherical shapes, is expected near the base of the crust in neutron stars. Large scale molecular dynamics simulations of pasta show long lived topological defects that could increase electron scattering and reduce both the thermal and electrical conductivities. We model a possible low conductivity pasta layer by increasing an impurity parameter Q_{imp}. Predictions of light curves for the low mass X-ray binary MXB 1659-29, assuming a large Q_{imp}, find continued late time cooling that is consistent with Chandra observations. The electrical and thermal conductivities are likely related. Therefore observations of late time crust cooling can provide insight on the electrical conductivity and the possible decay of neutron star magnetic fields (assuming these are supported by currents in the crust).

  16. Modeling the structure of magnetic fields in Neutron Stars: from the interior to the magnetosphere

    CERN Document Server

    Bucciantini, N; Del Zanna, L

    2015-01-01

    The phenomenology of the emission of pulsars and magnetars depends dramatically on the structure and properties of their magnetic field. In particular it is believed that the outbursting and flaring activity observed in AXPs and SRGs is strongly related to their internal magnetic field. Recent observations have moreover shown that charges are present in their magnetospheres supporting the idea that their magnetic field is tightly twisted in the vicinity of the star. In principle these objects offer a unique opportunity to investigate physics in a regime beyond what can be obtained in the laboratory. We will discuss the properties of equilibrium models of magnetized neutron stars, and we will show how internal and external currents can be related. These magnetic field configurations will be discussed considering also their stability, relevant for their origin and possibly connected to events like SNe and GRBs. We will also show what kind of deformations they induce in the star, that could lead to emission of g...

  17. Magnetic Field Evolution in Neutron Stars: One-Dimensional Multi-Fluid Model

    CERN Document Server

    Hoyos, J; Valdivia, J A

    2008-01-01

    This paper is the first in a series aimed at understanding the long-term evolution of neutron star magnetic fields. We model the stellar matter as an electrically neutral and lightly ionized plasma composed of three moving particle species: neutrons, protons, and electrons, which can be converted into each other by weak interactions (beta decays), suffer binary collisions, and be affected by each other's macroscopic electromagnetic fields. Since the evolution of the magnetic field occurs over thousands of years or more, compared to dynamical time scales (sound and Alfv\\'en) of milliseconds to seconds, we use a slow-motion approximation in which we neglect the inertial terms in the equations of motion for the particles. We restrict ourselves to a one-dimensional geometry in which the magnetic field points in one Cartesian direction but varies only along an orthogonal direction. We study the evolution of the system in three different ways: (i) estimating time scales directly from the equations, guided by physic...

  18. X-ray studies of neutron stars and their magnetic fields.

    Science.gov (United States)

    Makishima, Kazuo

    2016-01-01

    Utilizing results obtained over the past quarter century mainly with Japanese X-ray astronomy satellites, a review is given to some aspects of neutron stars (NSs), with a particular emphasis on the magnetic fields (MFs) of mass-accreting NSs and magnetars. Measurements of electron cyclotron resonance features in binary X-ray pulsars, using the Ginga and Suzaku observatories, clarified that their surface MFs are concentrated in a narrow range of (1-7) × 10(8) T. Extensive studies of magnetars with Suzaku reinforced their nature as neutron stars with truly strong MFs, and revealed several important clues to their formation, evolution, and physical states. Taking all these results into account, a discussion is made on the origin and evolution of these strong MFs. One possible scenario is that the MF of NSs is a manifestation of some fundamental physics, e.g., neutron spin alignment or chirality violation, and the MF makes transitions from strong to weak states. PMID:27169348

  19. Bubble detector's evaluation for neutron field measurement in a very known source

    Energy Technology Data Exchange (ETDEWEB)

    Ramalho, Eduardo; Silva, Ademir X. da, E-mail: ademir@nuclear.ufrj.b, E-mail: jdantas@con.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (PEN/COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Nuclear; Reina, Luiz, E-mail: reina@ien.gov.b [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Facure, Alessandro, E-mail: facure@cnen.gov.b [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    Measurements on neutron fields, mainly for dosimetric purposes, have been a major concern for ionizing radiation workers, because of the radiation protection issues. The present work aims to study the using of bubble detectors in neutron dosimetry and the Bubble Detector Spectrometer (BDS) was chosen for this task. Several experiments were performed in order to obtain spectra from such devices and their respective analysis and then they were compared to those which were obtained by other ways. An Am-Be calibration neutron source from Instituto de Radioprotecao e Dosimetria/Comissao Nacional de Energia Nuclear (IRD/CNEN) was used and its spectrum was compared to the one obtained by BDS. The possibility of the use of such devices as ambient dosimeters was also evaluated. Despite the uncertainties, especially in the lowest energy thresholds, the spectrum from BDS is in good agreement with the known ones and the use of BDS as a dosimeter demands a more detailed study due to some characteristics of the Am-Be source that produce high uncertainties in low energy thresholds. (author)

  20. Fully Relativistic Simulations of Black Holes and Neutron Stars with Global Magnetic Fields

    Science.gov (United States)

    Motl, Patrick

    We propose to conduct fully relativistic simulations of the merger of compact objects to investigate their connection to the population of short-duration, hard-spectrum gamma ray bursts. In particular, we will explore possible observational signatures that may lead to the simultaneous study of such mergers through both their gravitational radiation and through an electromagnetic counterpart. The combination of so-called multi-messenger observations can yield significantly more astrophysical content than either gravitational radiation or electromagnetic radiation alone. Through the work described herein to extend our previous efforts we will arrive at a numerical tool set that allows us to simulate the merger of a neutron star with another neutron star or with a black hole that include (i) full general relativity, (ii) a hydrodynamic treatment of the neutron star material, (iii) electromagnetic fields in both the stellar material and globally and (iv) a treatment of energy transport and losses via neutrinos. These physics modules run within the publicly available, distributed adaptive mesh refinement framework (named HAD) developed by our collaboration. The numerical tools that we develop and release will likely be of use in other areas of computational astrophysics. Furthermore, predications and the interpretation of the signatures from compact object mergers may make a timely contribution to current efforts to study these systems observationally as well as efforts underway to detect these mergers through their gravitational radiation for the first time.

  1. Study of neutron magic drip-line nuclei within relativistic mean-field plus BCS approach

    International Nuclear Information System (INIS)

    Encouraged by the success of relativistic mean-field plus BCS (RMF + BCS) approach for the description of the ground state properties of the chains of isotopes of proton magic nuclei with proton number Z = 8, 20, 28, 50 and 82 as well as those of proton sub-magic nuclei with Z = 40, we have further employed it, in an analogous manner, for a detailed calculations of the ground state properties of the neutron magic isotones with neutron number N = 8, 20, 28, 50, 82 and 126 as well as those of neutron sub-magic isotones with N = 40 using the TMA force parametrizations in order to explore low lying resonance and other exotic phenomenon near drip-lines. The results of these calculations for wave function, single particle pairing gaps etc. are presented here to demonstrate the general validity of our RMF + BCS approach. It is found that, in some of the proton-rich nuclei in the vicinity of the proton drip-line, the main contribution to the pairing correlations is provided by the low-lying resonant states, in addition to the contributions coming from the states close to the Fermi surface, which results extended proton drip-line for isotonic chain. (author)

  2. Kvantitativ benchmark - Produktionsvirksomheder

    DEFF Research Database (Denmark)

    Sørensen, Ole H.; Andersen, Vibeke

    Rapport med resultatet af kvantitativ benchmark over produktionsvirksomhederne i VIPS projektet.......Rapport med resultatet af kvantitativ benchmark over produktionsvirksomhederne i VIPS projektet....

  3. The PRISM Benchmark Suite

    OpenAIRE

    Kwiatkowsa, Marta; Norman, Gethin; Parker, David

    2012-01-01

    We present the PRISM benchmark suite: a collection of probabilistic models and property specifications, designed to facilitate testing, benchmarking and comparisons of probabilistic verification tools and implementations.

  4. Neutron spectral measurements in an intense photon field associated with a high-energy x-ray radiotherapy machine.

    Science.gov (United States)

    Holeman, G R; Price, K W; Friedman, L F; Nath, R

    1977-01-01

    High-energy x-ray radiotherapy machines in the supermegavoltage region generate complex neutron energy spectra which make an exact evaluation of neutron shielding difficult. Fast neutrons resulting from photonuclear reactions in the x-ray target and collimators undergo successive collisions in the surrounding materials and are moderated by varying amounts. In order to examine the neutron radiation exposures quantitatively, the neutron energy spectra have been measured inside and outside the treatment room of a Sagittaire medical linear accelerator (25-MV x rays) located at Yale-New Haven Hospital. The measurements were made using a Bonner spectrometer consisting of 2-, 3-, 5-, 8-, 10- and 12-in.-diameter polyethylene spheres with 6Li and 7Li thermoluminescent dosimeter (TLD) chips at the centers, in addition to bare and cadmium-covered chips. The individual TLD chips were calibrated for neutron and photon response. The spectrometer was calibrated using a known PuBe spectrum Spectrometer measurements were made at Yale Electron Accelerator Laboratory and results compared with a neutron time-of-flight spectrometer and an activation technique. The agreement between the results from these independent methods is found to be good, except for the measurements in the direct photon beam. Quality factors have been inferred for the neutron fields inside and outside the treatment room. Values of the inferred quality factors fall primarily between 4 and 8, depending on location.

  5. Nuclear reaction and penetration through matter of neutrons above 20 MeV using p-Li quasi-monoenergetic neutron field

    International Nuclear Information System (INIS)

    Quasi-monoenergetic neutron fields above 20 MeV have been developed from Li(p,n) reaction at three laboratories in Japan (INS-SF cyclotron. CYRIC-AVF cyclotron and TIARA-AVF cyclotron) and are evaluated based on the measurement of the energy spectra. Penetration of 40.5 MeV monoenergetic neutrons (43 MeV proton energy) at TIARA through iron and concrete was investigated and the result agreed well with calculation with MORSE code using the cross section of DLC-119/HILO 86. Measurements of neutron activation and nuclear spallation cross section were carried out at INS and TIARA and the results were examined. (T.H.)

  6. Optimal design of measurement network for neutronic activity field reconstruction by data assimilation

    International Nuclear Information System (INIS)

    An optimal reconstruction of the neutronic activity field can be determined for a nuclear reactor core using a data assimilation framework to merge information from models and measurements. In this paper, we focus on solving the inverse problem of determining an optimal repartition of the measuring instruments within the core, to get the best possible results from the data assimilation reconstruction procedure. The position optimisation is realised using a Simulated Annealing algorithm, based on the Metropolis-Hastings proposition. Moreover, algebraic improvements of data assimilation have been developed, optimising their computational performance, and are presented here.

  7. Neutron scattering study of crystal-field excitations in TmTe

    International Nuclear Information System (INIS)

    Inelastic neutron scattering measurements have been carried out on TmTe to settle the controversial issue of the crystal-field level scheme in this compound. By comparing data obtained with different energy resolutions, it is shown that the total splitting cannot exceed 2 meV. The energies and intensities of the excitations are consistent with a Γ8 quartet ground-state, but their width is appreciably larger than the resolution. This broadening may be due to spin fluctuations and/or a weak quadrupolar splitting of the quartet state. (orig.)

  8. Dose equivalent conversion coefficients, instrument and dosemeter responses for a set of neutron radiation fields

    International Nuclear Information System (INIS)

    The results are presented of calculations of spectrum (energy and angle) weighted conversion coefficients from fluence to the quantities effective dose equivalent, ambient dose equivalent (H*(10)), directional dose equivalent at 10 mm (H'(10)) and MADE; and of the responses per unit fluence of a spherical rem meter, a nuclear emulsion dosemeter, an albedo dosemeter and a PADC (CR39) dosemeter, for a set of neutron spectra. Calculations have been performed for both unidirectional fields and for rotational symmetry. The values of conversion coefficients and instrument and dosemeter responses are compared. (author)

  9. In vivo Observation of Tree Drought Response with Low-Field NMR and Neutron Imaging

    OpenAIRE

    Malone, Michael W.; Yoder, Jacob; Hunter, James F.; Espy, Michelle A.; Dickman, Lee T.; Nelson, Ron O.; Sven C. Vogel; Sandin, Henrik J.; Sevanto, Sanna

    2016-01-01

    Using a simple low-field NMR system, we monitored water content in a living tree in a greenhouse over 2 months. By continuously running the system, we observed changes in tree water content on a scale of half an hour. The data showed a diurnal change in water content consistent both with previous NMR and biological observations. Neutron imaging experiments show that our NMR signal is primarily due to water being rapidly transported through the plant, and not to other sources of hydrogen, such...

  10. Integral test on activation cross section of tag gas nuclides using fast neutron spectrum fields

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-03-01

    Activation cross sections of tag gas nuclides, which will be used for the failed fuel detection and location in FBR plants, were evaluated by the irradiation tests in the fast neutron spectrum fields in JOYO and YAYOI. The comparison of their measured radioactivities and the calculated values using the JENDL-3.2 cross section set showed that the C/E values ranged from 0.8 to 2.8 for the calibration tests in YAYOI and that the present accuracies of these cross sections were confirmed. (author)

  11. High energy neutron spectroscopy of crystal field excitations in NpO2

    International Nuclear Information System (INIS)

    Neutron spectroscopy has been applied to study the crystal field potential in NpO2. The inelastic scattering cross section shows a broad magnetic peak which is split into two components and is centred at about 55 meV. A quasielastic magnetic signal extending up to about 30 meV is also observed at temperatures below the phase transition at 25 K. The inelastic peak is shown to originate from excitations between the Γ8(2) and Γ8(1) crystal field quartets. Its position is in agreement with the value estimated by scaling the crystal field potential of UO2 to the Np4+ case. Several mechanisms which could be responsible for the observed splitting are discussed. (author)

  12. Interior Vector Magnetic Field Monitoring via External Measurements for the SNS Neutron EDM Experiment

    Science.gov (United States)

    Nouri, Nima; Brown, Michael; Carr, Robert; Filippone, Bradley; Osthelder, Charles; Plaster, Bradley; Slutsky, Simon; Swank, Christopher

    2015-10-01

    A prototype of a magnetic field monitoring system designed to reconstruct the vector magnetic field components (and, hence, all nine of the ∂Bi / ∂xj field gradients) within the interior measurement fiducial volume solely from external measurements is under development for the SNS neutron EDM experiment. A first-generation room-temperature prototype array has already been tested. A second-generation prototype array consisting of 12 cryogenic-compatible fluxgate magnetometer probes will be deployed within the cold region of the experiment's 1 / 3 -scale cryogenic magnet testing apparatus. We will report progress towards the development of this second-generation prototype. This work was supported in part by the U. S. Department of Energy Office of Nuclear Physics under Award No. DE-FG02-08ER41557.

  13. Study of the radial behavior of non-steady neutron field produced by a 14-MeV neutron generator in constructing the PNL formation standards

    International Nuclear Information System (INIS)

    Presented are results of the analysis of radial saturation of a non-steady neutron field produced by a 14-MeV pulsed neutron generator in constructing reference standards for the PNL logging tool. These standards were constructed as formation models reproducing such parameters as porosity and neutron characteristics of rocks - thermal neutron absorption macro cross-section and diffusion coefficient. Radial sizes of standards depend crucially on the sounding depth of PNL. Radial sizes were found with due regard of known 2-group diffusion calculations (A. Shkolnikov and S. Kantor, 1976) and original Monte-Carlo calculations made together with V. Velizhanin. The comparison evidences of the overestimated radii of saturated models proposed by a 2-group diffusion approximation as compared to Monte-Carlo values. Analyzed are functions of integral and differential radial sensitivities of the PNL response (density of thermal neutron flux) for PNL spacing of 0-100 cm, time delay of up to 3 ms (with a time discretization of 50 mcs), for the formation porosity of 0, 10, 20, 30, and 40 %. Compared are the contributions of axial layers to the PNL response depending on the tool's spacing and formation porosity. (author)

  14. Relativistic mean field study of 'islands of inversion' in neutron rich Z = 17 - 23, 37 - 40 and 60 - 64 nuclei

    CERN Document Server

    Singh, S K; Mishra, R N

    2013-01-01

    We study the extremely neutron-rich nuclei for $Z = 17 - 23$, $37 - 40$ and $60 - 64$ regions of the periodic table by using axially deformed relativistic mean field formalism with NL3* parametrization. Based on the analysis of binding energy, two neutron separation energy, quadrupole deformation and root mean square radii, we emphasized the speciality of these considered regions which are recently predicted islands of inversion.

  15. Benchmark Database on Isolated Small Peptides Containing an Aromatic Side Chain: Comparison Between Wave Function and Density Functional Theory Methods and Empirical Force Field

    Energy Technology Data Exchange (ETDEWEB)

    Valdes, Haydee; Pluhackova, Kristyna; Pitonak, Michal; Rezac, Jan; Hobza, Pavel

    2008-03-13

    A detailed quantum chemical study on five peptides (WG, WGG, FGG, GGF and GFA) containing the residues phenylalanyl (F), glycyl (G), tryptophyl (W) and alanyl (A)—where F and W are of aromatic character—is presented. When investigating isolated small peptides, the dispersion interaction is the dominant attractive force in the peptide backbone–aromatic side chain intramolecular interaction. Consequently, an accurate theoretical study of these systems requires the use of a methodology covering properly the London dispersion forces. For this reason we have assessed the performance of the MP2, SCS-MP2, MP3, TPSS-D, PBE-D, M06-2X, BH&H, TPSS, B3LYP, tight-binding DFT-D methods and ff99 empirical force field compared to CCSD(T)/complete basis set (CBS) limit benchmark data. All the DFT techniques with a ‘-D’ symbol have been augmented by empirical dispersion energy while the M06-2X functional was parameterized to cover the London dispersion energy. For the systems here studied we have concluded that the use of the ff99 force field is not recommended mainly due to problems concerning the assignment of reliable atomic charges. Tight-binding DFT-D is efficient as a screening tool providing reliable geometries. Among the DFT functionals, the M06-2X and TPSS-D show the best performance what is explained by the fact that both procedures cover the dispersion energy. The B3LYP and TPSS functionals—not covering this energy—fail systematically. Both, electronic energies and geometries obtained by means of the wave-function theory methods compare satisfactorily with the CCSD(T)/CBS benchmark data.

  16. Neutron Radiography

    Directory of Open Access Journals (Sweden)

    A. R. Reddy

    1982-07-01

    Full Text Available The field of neutron radiography with special reference to isotopic neutron radiography has been reviewed. Different components viz., sources, collimators, imaging systems are described. Various designs of neutron radiography facilities, their relative merits and demerits , the appropriateness of each design depending on the object to be radiographed, and economics of each technique are also dealt. The applications of neutron radiography are also briefly presented.

  17. Responses of conventional and extended-range neutron detectors in mixed radiation fields around a 150-MeV electron LINAC

    International Nuclear Information System (INIS)

    This study analyzed the responses of two types of neutron detector in mixed gamma-ray and neutron radiation fields around a 150-MeV electron linear accelerator (LINAC). The detectors were self-assembled, high efficiency, and designed in two configurations: (1) a conventional moderated-type neutron detector based on a large cylindrical He-3 proportional counter; and (2) an extended-range version with an embedded layer of lead in the moderator to increase the detector’s sensitivity to high-energy neutrons. Two sets of the detectors were used to measure neutrons at the downstream and lateral locations simultaneously, where the radiation fields differed considerably in intensities and spectra of gamma rays and neutrons. Analyzing the detector responses through a comparison between calculations and measurements indicated that not only neutrons but also high-energy gamma rays (>5 MeV) triggered the detectors because of photoneutrons produced in the detector materials. In the lateral direction, the contribution of photoneutrons to both detectors was negligible. Downstream of the LINAC, where high-energy photons were abundant, photoneutrons contributed approximately 6% of the response of the conventional neutron detector; however, almost 50% of the registered counts of the extended-range neutron detector were from photoneutrons because of the presence of the detector rather than the effect of the neutron field. Dose readings delivered by extended-range neutron detectors should be interpreted cautiously when used in radiation fields containing a mixture of neutrons and high-energy gamma rays

  18. Radiation Detection Computational Benchmark Scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Shaver, Mark W.; Casella, Andrew M.; Wittman, Richard S.; McDonald, Ben S.

    2013-09-24

    Modeling forms an important component of radiation detection development, allowing for testing of new detector designs, evaluation of existing equipment against a wide variety of potential threat sources, and assessing operation performance of radiation detection systems. This can, however, result in large and complex scenarios which are time consuming to model. A variety of approaches to radiation transport modeling exist with complementary strengths and weaknesses for different problems. This variety of approaches, and the development of promising new tools (such as ORNL’s ADVANTG) which combine benefits of multiple approaches, illustrates the need for a means of evaluating or comparing different techniques for radiation detection problems. This report presents a set of 9 benchmark problems for comparing different types of radiation transport calculations, identifying appropriate tools for classes of problems, and testing and guiding the development of new methods. The benchmarks were drawn primarily from existing or previous calculations with a preference for scenarios which include experimental data, or otherwise have results with a high level of confidence, are non-sensitive, and represent problem sets of interest to NA-22. From a technical perspective, the benchmarks were chosen to span a range of difficulty and to include gamma transport, neutron transport, or both and represent different important physical processes and a range of sensitivity to angular or energy fidelity. Following benchmark identification, existing information about geometry, measurements, and previous calculations were assembled. Monte Carlo results (MCNP decks) were reviewed or created and re-run in order to attain accurate computational times and to verify agreement with experimental data, when present. Benchmark information was then conveyed to ORNL in order to guide testing and development of hybrid calculations. The results of those ADVANTG calculations were then sent to PNNL for

  19. Preequilibrium neutron emission in heavy ion reaction: Mean field effect and multiple emission

    Science.gov (United States)

    Paul, Sabyasachi; Nandy, Maitreyee; Mohanty, A. K.; Gambhir, Y. K.

    2016-09-01

    Effects of nuclear mean field and of multiple preequilibrium (PEQ) emission on double differential neutron multiplicity distribution from heavy ion reactions (12C+165Ho and 20Ne+165Ho ) at 10-30 MeV/u have been investigated in the framework of the semiclassical formalism for heavy ion reaction (henceforth termed "HION") developed earlier. HION follows the equilibration of a target+projectile composite system through the kinematics of two-body scattering. In the present work nuclear density distribution in the composite system is estimated in the relativistic mean field (RMF) approach. The nucleon-nucleon collision rates and subsequently the nucleon emission probability are calculated from this density distribution. A second approach based on a semiphenomenological formalism is also used for nuclear density distribution. Energy-angle distribution of neutron multiplicities calculated with this modified HION model coupled with multiple PEQ emission could reproduce the measured data of earlier workers in the projectile energy range of 10-30 MeV/u.

  20. Electrical conductivity of a warm neutron star crust in magnetic fields

    Science.gov (United States)

    Harutyunyan, Arus; Sedrakian, Armen

    2016-08-01

    We study the electrical conductivity of finite-temperature crust of a warm compact star which may be formed in the aftermath of a supernova explosion or a binary neutron star merger as well as when a cold neutron star is heated by accretion of material from a companion. We focus on the temperature-density regime where plasma is in the liquid state and, therefore, the conductivity is dominated by the electron scattering off correlated nuclei. The dynamical screening of this interaction is implemented in terms of the polarization tensor computed in the hard-thermal-loop effective field theory of QED plasma. The correlations of the background ionic component are accounted for via a structure factor derived from Monte Carlo simulations of one-component plasma. With this input we solve the Boltzmann kinetic equation in relaxation time approximation taking into account the anisotropy of transport due to the magnetic field. The electrical conductivity tensor is studied numerically as a function of temperature and density for carbon and iron nuclei as well as density-dependent composition of zero-temperature dense matter in weak equilibrium with electrons. We also provide accurate fit formulas to our numerical results as well as supplemental tables which can be used in dissipative magneto-hydrodynamics simulations of warm compact stars.

  1. Study on the manganese distribution in the soil of an agricultural field using neutron activation analysis method

    International Nuclear Information System (INIS)

    Manganese distribution in the soil of an agricultural field was evaluated by neutron activation analysis. The accuracy and precision of the method were verified by the analysis of two Standard Reference Materials with different manganese concentration in the experimental field, through one schematic diagram. (author). 7 refs., 1 fig., 2 tabs

  2. Out-of-field doses and neutron dose equivalents for electron beams from modern Varian and Elekta linear accelerators.

    Science.gov (United States)

    Cardenas, Carlos E; Nitsch, Paige L; Kudchadker, Rajat J; Howell, Rebecca M; Kry, Stephen F

    2016-01-01

    Out-of-field doses from radiotherapy can cause harmful side effects or eventually lead to secondary cancers. Scattered doses outside the applicator field, neutron source strength values, and neutron dose equivalents have not been broadly investigated for high-energy electron beams. To better understand the extent of these exposures, we measured out-of-field dose characteristics of electron applicators for high-energy electron beams on two Varian 21iXs, a Varian TrueBeam, and an Elekta Versa HD operating at various energy levels. Out-of-field dose profiles and percent depth-dose curves were measured in a Wellhofer water phantom using a Farmer ion chamber. Neutron dose was assessed using a combination of moderator buckets and gold activation foils placed on the treatment couch at various locations in the patient plane on both the Varian 21iX and Elekta Versa HD linear accelerators. Our findings showed that out-of-field electron doses were highest for the highest electron energies. These doses typically decreased with increasing distance from the field edge but showed substantial increases over some distance ranges. The Elekta linear accelerator had higher electron out-of-field doses than the Varian units examined, and the Elekta dose profiles exhibited a second dose peak about 20 to 30 cm from central-axis, which was found to be higher than typical out-of-field doses from photon beams. Electron doses decreased sharply with depth before becoming nearly constant; the dose was found to decrease to a depth of approximately E(MeV)/4 in cm. With respect to neutron dosimetry, Q values and neutron dose equivalents increased with electron beam energy. Neutron contamination from electron beams was found to be much lower than that from photon beams. Even though the neutron dose equivalent for electron beams represented a small portion of neutron doses observed under photon beams, neutron doses from electron beams may need to be considered for special cases. PMID:27455499

  3. Characterization of the neutronic fields obtained by means of neutron traps inside the nuclear reactor core IPEN/MB-01

    International Nuclear Information System (INIS)

    This paper presents the results of the neutron flux values obtained from the deployment of a Flux Trap of neutrons in the reactor core IPEN/MB-01. We analyzed several configurations of Flux Traps deployed in the reactor core IPEN/MB-01 in order to get elected to Flux Trap configuration more efficient. To characterize the neutron spectrum were irradiated in the center of the Flux Trap activation detectors of different materials (Au, Sc, In, Ti, Ni). The respective gamma spectroscopy of these elements after irradiation with and without cadmium cover, provided the experimental values of the nuclear reaction rates (saturation activity) by the target nuclei and their uncertainties used as input to the code SANDBP who calculated the energy spectrum of neutrons in the center of the 'Flux-Trap' in 50 energy groups, using the input spectra calculated at the irradiation position (center of the 'Flux Trap') by codes for Reactor Physics. The results found an increase in the thermal neutron flux in the center of the Flux Trap configuration 203 for the standard configuration (default) of about 350% without having the need to increase the reactor power. We also made comparisons between the spectra obtained by SANDBP deployed, compared to those calculated by MCNP-4C code and XSDRNPM. The spatial characterization of the thermal neutron flux is made with activation foils in the form of an infinitely dilute bulk alloy of 1% Au and 99% Al in some internal points of the configuration 203 (axially to Flux Trap and adjacent radial) and the results showed a significant increase in the magnitude of their values when compared to standard rectangular configuration. (author)

  4. Rapidly rotating neutron stars with a massive scalar field - structure and universal relations

    CERN Document Server

    Doneva, Daniela D

    2016-01-01

    We construct rapidly rotating neutron star models in scalar-tensor theories with a massive scalar field. The fact that the scalar field has nonzero mass leads to very interesting results since the allowed range of values of the coupling parameters is significantly broadened. These deviations from pure general relativity can be very large for values of the parameters that are in agreement with the observations. The rapid rotation can magnify the differences several times compared to the static case. The universal relations between the normalized moment of inertia and quadrupole moment are also investigated both for the slowly and rapidly rotating cases. The results show that these relations are still EOS independent up to a large extend and the deviations from pure general relativity can be large. This places the massive scalar-tensor theories amongst the few alternative theories of gravity that can be tested via the universal $I$-Love-$Q$ relations.

  5. The new high field photoexcitation muon spectrometer at the ISIS pulsed neutron and muon source

    CERN Document Server

    Yokoyama, K; Murahari, P; Wang, K; Dunstan, D J; Waller, S P; McPhail, D J; Hillier, A D; Henson, J; Harper, M R; Heathcote, P; Drew, A J

    2016-01-01

    A high power pulsed laser system has been installed on the high magnetic field muon instrument (HiFi) at the ISIS pulsed neutron and muon source, situated at the STFC Rutherford Appleton Laboratory in the UK. The upgrade enables one to perform light-pump muon-probe experiments under a high field, which opens up a brand-new area in the muon spin spectroscopy. In this report we overview the principle of the HiFi Laser system, and describe the newly developed techniques and devices that enable a controlled photoexcitation in the muon instrument. A demonstration experiment illustrates the unique combination of the photoexcited system and avoided level crossing technique.

  6. Ernst formulation of axisymmetric fields in f (R ) gravity: Applications to neutron stars and gravitational waves

    Science.gov (United States)

    Suvorov, Arthur George; Melatos, Andrew

    2016-08-01

    The Ernst formulation of the Einstein equations is generalized to accommodate f (R ) theories of gravity. It is shown that, as in general relativity, the axisymmetric f (R ) field equations for a vacuum spacetime that is either stationary or cylindrically symmetric reduce to a single, nonlinear differential equation for a complex-valued scalar function. As a worked example, we apply the generalized Ernst equations to derive a f (R ) generalization of the Zipoy-Voorhees metric, which may be used to describe the gravitational field outside of an ellipsoidal neutron star. We also apply the theory to investigate the phase speed of large-amplitude gravitational waves in f (R ) gravity in the context of solitonlike solutions that display shock-wave behavior across the causal boundary.

  7. PRISMATIC CORE COUPLED TRANSIENT BENCHMARK

    Energy Technology Data Exchange (ETDEWEB)

    J. Ortensi; M.A. Pope; G. Strydom; R.S. Sen; M.D. DeHart; H.D. Gougar; C. Ellis; A. Baxter; V. Seker; T.J. Downar; K. Vierow; K. Ivanov

    2011-06-01

    The Prismatic Modular Reactor (PMR) is one of the High Temperature Reactor (HTR) design concepts that have existed for some time. Several prismatic units have operated in the world (DRAGON, Fort St. Vrain, Peach Bottom) and one unit is still in operation (HTTR). The deterministic neutronics and thermal-fluids transient analysis tools and methods currently available for the design and analysis of PMRs have lagged behind the state of the art compared to LWR reactor technologies. This has motivated the development of more accurate and efficient tools for the design and safety evaluations of the PMR. In addition to the work invested in new methods, it is essential to develop appropriate benchmarks to verify and validate the new methods in computer codes. The purpose of this benchmark is to establish a well-defined problem, based on a common given set of data, to compare methods and tools in core simulation and thermal hydraulics analysis with a specific focus on transient events. The benchmark-working group is currently seeking OECD/NEA sponsorship. This benchmark is being pursued and is heavily based on the success of the PBMR-400 exercise.

  8. Ground Albedo Neutron Sensing (GANS) method for measurements of soil moisture in cropped fields

    Science.gov (United States)

    Andres Rivera Villarreyes, Carlos; Baroni, Gabriele; Oswald, Sascha E.

    2013-04-01

    Measurement of soil moisture at the plot or hill-slope scale is an important link between local vadose zone hydrology and catchment hydrology. However, so far only few methods are on the way to close this gap between point measurements and remote sensing. This study evaluates the applicability of the Ground Albedo Neutron Sensing (GANS) for integral quantification of seasonal soil moisture in the root zone at the scale of a field or small watershed, making use of the crucial role of hydrogen as neutron moderator relative to other landscape materials. GANS measurements were performed at two locations in Germany under different vegetative situations and seasonal conditions. Ground albedo neutrons were measured at (i) a lowland Bornim farmland (Brandenburg) cropped with sunflower in 2011 and winter rye in 2012, and (ii) a mountainous farmland catchment (Schaefertal, Harz Mountains) since middle 2011. At both sites depth profiles of soil moisture were measured at several locations in parallel by frequency domain reflectometry (FDR) for comparison and calibration. Initially, calibration parameters derived from a previous study with corn cover were tested under sunflower and winter rye periods at the same farmland. GANS soil moisture based on these parameters showed a large discrepancy compared to classical soil moisture measurements. Therefore, two new calibration approaches and four different ways of integration the soil moisture profile to an integral value for GANS were evaluated in this study. This included different sets of calibration parameters based on different growing periods of sunflower. New calibration parameters showed a good agreement with FDR network during sunflower period (RMSE = 0.023 m3 m-3), but they underestimated soil moisture in the winter rye period. The GANS approach resulted to be highly affected by temporal changes of biomass and crop types which suggest the need of neutron corrections for long-term observations with crop rotation. Finally

  9. Realistic exact solution for the exterior field of a rotating neutron star

    Science.gov (United States)

    Pachón, Leonardo A.; Rueda, Jorge A.; Sanabria-Gómez, José D.

    2006-05-01

    A new six-parametric, axisymmetric, and asymptotically flat exact solution of Einstein-Maxwell field equations having reflection symmetry is presented. It has arbitrary physical parameters of mass, angular momentum, mass-quadrupole moment, current octupole moment, electric charge, and magnetic dipole, so it can represent the exterior field of a rotating, deformed, magnetized, and charged object; some properties of the closed-form analytic solution such as its multipolar structure, electromagnetic fields, and singularities are also presented. In the vacuum case, this analytic solution is matched to some numerical interior solutions representing neutron stars, calculated by Berti and Stergioulas [E. Berti and N. Stergioulas, Mon. Not. R. Astron. Soc.MNRAA40035-8711 350, 1416 (2004)10.1111/j.1365-2966.2004.07740.x], imposing that the multipole moments be the same. As an independent test of accuracy of the solution to describe exterior fields of neutron stars, we present an extensive comparison of the radii of innermost stable circular orbits (ISCOs) obtained from the Berti and Stergioulas numerical solutions, the Kerr solution [R. P. Kerr, Phys. Rev. Lett.PRLTAO0031-9007 11, 237 (1963)10.1103/PhysRevLett.11.237], the Hartle and Thorne solution [J. B. Hartle and K. S. Thorne, Astrophys. J.ASJOAB0004-637X 153, 807 (1968)10.1086/149707], an analytic series expansion derived by Shibata and Sasaki [M. Shibata and M. Sasaki, Phys. Rev. DPRVDAQ0556-2821 58, 104011 (1998)10.1103/PhysRevD.58.104011], and our exact solution. We found that radii of ISCOs from our solution fits better than others with realistic numerical interior solutions.

  10. Benchmark data set for wheat growth models: field experiments and AgMIP multi-model simulations

    NARCIS (Netherlands)

    Supit, I.; Wolf, J.; Asseng, S.; Ewert, F.; Martre, P.; Rosenzweig, C.

    2015-01-01

    The data set includes a current representative management treatment from detailed, quality-tested sentinel field experiments with wheat from four contrasting environments including Australia, The Netherlands, India and Argentina. Measurements include local daily climate data (solar radiation, maximu

  11. Out-of-field photon and neutron dose equivalents from step-and-shoot intensity-modulated radiation therapy

    International Nuclear Information System (INIS)

    Purpose: To measure the photon and neutron out-of-treatment-field dose equivalents to various organs from different treatment strategies (conventional vs. intensity-modulated radiation therapy [IMRT]) at different treatment energies and delivered by different accelerators. Methods and Materials: Independent measurements were made of the photon and neutron out-of-field dose equivalents resulting from one conventional and six IMRT treatments for prostate cancer. The conventional treatment used an 18-MV beam from a Clinac 2100; the IMRT treatments used 6-MV, 10-MV, 15-MV, and 18-MV beams from a Varian Clinac 2100 accelerator and 6-MV and 15-MV beams from a Siemens Primus accelerator. Photon doses were measured with thermoluminescent dosimeters in a Rando phantom, and neutron fluence was measured with gold foils. Dose equivalents to the colon, liver, stomach, lung, esophagus, thyroid, and active bone marrow were determined for each treatment approach. Results: For each treatment approach, the relationship between dose equivalent per MU, distance from the treatment field, and depth in the patient was examined. Photon dose equivalents decreased approximately exponentially with distance from the treatment field. Neutron dose equivalents were independent of distance from the treatment field and decreased with increasing tissue depth. Neutrons were a significant contributor to the out-of field dose equivalent for beam energies ≥15 MV. Conclusions: Out-of-field photon and neutron dose equivalents can be estimated to any point in a patient undergoing a similar treatment approach from the distance of that point to the central axis and from the tissue depth. This information is useful in determining the dose to critical structures and in evaluating the risk of associated carcinogenesis

  12. Computational benchmark problem for deep penetration in iron

    International Nuclear Information System (INIS)

    A calculational benchmark problem which is simple to model and easy to interpret is described. The benchmark consists of monoenergetic 2-, 4-, or 40-MeV neutrons normally incident upon a 3-m-thick pure iron slab. Currents, fluxes, and radiation doses are tabulated throughout the slab

  13. Workplace characterisation in mixed neutron-gamma fields, specific requirements and available methods at high-energy accelerators

    International Nuclear Information System (INIS)

    A good knowledge of the radiation field present outside the shielding of high-energy particle accelerators is very important to be able to select the type of detectors (active and/or passive) to be employed for area monitoring and the type of personal dosemeter required for estimating the doses received by individuals. Around high-energy electron and proton accelerators the radiation field is usually dominated by neutrons and photons, with minor contributions from other charged particles. Under certain circumstances, muon radiation in the forward beam direction may also be present. Neutron dosimetry and spectrometry are of primary importance to characterise the radiation field and thus to correctly evaluate personnel exposure. Starting from the beam parameters important for radiation monitoring, the paper first briefly reviews the stray radiation fields encountered around high-energy accelerators and then addresses the relevant techniques employed for their monitoring. Recent developments to increase the response of neutron measuring devices beyond 10-20 MeV are illustrated. Instruments should be correctly calibrated either in reference monoenergetic radiation fields or in a field similar to the field in which they are used (workplace calibration). The importance of the instrument calibration is discussed and available neutron calibration facilities are briefly reviewed. (authors)

  14. Spin period change and the magnetic fields of neutron stars in Be X-ray binaries in the SMC

    Directory of Open Access Journals (Sweden)

    Klus H.

    2014-01-01

    Full Text Available We report on the long term average spin period, rate of change of spin period and X-ray luminosity during outbursts for 42 Be X-ray binary systems in the Small Magellanic Cloud. We also collect and calculate parameters of each system and use this data to determine that all systems contain a neutron star which is accreting via a disc, rather than a wind, and that if these neutron stars are near spin equilibrium, then over half of them, including all with spin periods over about 100 seconds, have magnetic fields over the quantum critical level of 4.4×1013 G. If these neutron stars are not close to spin equilibrium, then their magnetic fields are inferred to be much lower, on the order of 106-1010 G, comparable to the fields of neutron stars in low mass X-ray binaries. Both results are unexpected and have implications for the rate of magnetic field decay and the isolated neutron star population.

  15. Benchmark calculations of nonconservative charged-particle swarms in dc electric and magnetic fields crossed at arbitrary angles.

    Science.gov (United States)

    Dujko, S; White, R D; Petrović, Z Lj; Robson, R E

    2010-04-01

    A multiterm solution of the Boltzmann equation has been developed and used to calculate transport coefficients of charged-particle swarms in gases under the influence of electric and magnetic fields crossed at arbitrary angles when nonconservative collisions are present. The hierarchy resulting from a spherical-harmonic decomposition of the Boltzmann equation in the hydrodynamic regime is solved numerically by representing the speed dependence of the phase-space distribution function in terms of an expansion in Sonine polynomials about a Maxwellian velocity distribution at an internally determined temperature. Results are given for electron swarms in certain collisional models for ionization and attachment over a range of angles between the fields and field strengths. The implicit and explicit effects of ionization and attachment on the electron-transport coefficients are considered using physical arguments. It is found that the difference between the two sets of transport coefficients, bulk and flux, resulting from the explicit effects of nonconservative collisions, can be controlled either by the variation in the magnetic field strengths or by the angles between the fields. In addition, it is shown that the phenomena of ionization cooling and/or attachment cooling/heating previously reported for dc electric fields carry over directly to the crossed electric and magnetic fields. The results of the Boltzmann equation analysis are compared with those obtained by a Monte Carlo simulation technique. The comparison confirms the theoretical basis and numerical integrity of the moment method for solving the Boltzmann equation and gives a set of well-established data that can be used to test future codes and plasma models. PMID:20481843

  16. In-situ neutron scattering studies of magnetic shape memory alloys under stress, temperature, and magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Donald W [Los Alamos National Laboratory; Sisneros, Thomas A [Los Alamos National Laboratory; Kabra, Saurabh [ANSTO/AUSTRALIA; Lograsso, Thomas A [AMES LAB; Schlagel, Deborah [AMES LAB

    2010-01-01

    We have utilized the SMARTS engineering neutron diffractometer to study the crystallographic orientation and phase transformations in the ferromagnetic shape memory alloy Ni 2MnGa under conditions of temperature (200-600K), stress (500MPa), and magnetic field (2T). Neutrons are uniquely suited to probe the crystallographic response of materials to external stimuli because of their high penetration, which allows them to sample the bulk of the material (as opposed to the surface) as well as pass through environmental chambers. A single crystal of Ni{sub 5}MnGa was repeatedly thermally cycled through the Austenitic-Martensitic phase transformation under varying conditions of applied stress, magnetic field or both. In-situ neutron diffraction was used to quantitatively monitor the population of the crystallographic variants in the martensitic phase as a function of the external stimuli during cooling. Neutron diffraction was used to monitor variant selection in the Ferromagnetic Shape Memory Alloy Ni{sub 2}Mn Ga during austenitic to martensitic transformation under varying conditions of externally applied stress and magnetic field. Qualitatively, the results were to be expected in this simple example. The shorter and magnetically soft c-axis of the tetragonal martensitic phase aligned with the compressive stress or magnetic field. However, neutron diffraction proved useful in directly quantifying the selection of the preferred variant by external influence. For instance, by quantifying the variant selection, the neutron diffraction results made apparent that the sample 'remembered' a loading cycle following a 'reset' cycle with no external applied stress. Moreover, the power of in-situ neutron diffraction will become more apparent when applied to more complex, less understood, samples such as polycrystalline samples or composite samples.

  17. MeV-GeV neutrino propagation as a signal of magnetic field amplification in neutron star merger

    Science.gov (United States)

    Fraija, N.

    2016-09-01

    Short gamma-ray bursts (sGRBs) have widely been accepted to arise from a compact object binary merger; neutron star-neutron star or neutron star-black hole. During the merger of a binary neutron star system, magnetic field can be amplified beyond magnetar field strength (∼1015-1016 G) by Kelvin-Helmholtz instabilities. Considering this effect on the GRB "fireball" dynamics, we study the emission, propagation and oscillation of multi MeV-GeV neutrinos through their self-energies and using these we compute the neutrino effective potential up to order MW-4. Additionally, we calculate the number of neutrino events and neutrino flavor ratios that we would expect on Hyper-Kamiokande and DeepCore experiments. We found that MeV neutrinos in a strong magnetic field could provide information of the topology of the field, and that the number of GeV neutrinos expected in DeepCore detector would be directly affected by the strength of the field. It is worth noting that our estimates correspond to the only trustworthy method for verifying the effect of the magnetic field amplification.

  18. Neutron and photon spectrometry with liquid scintillation detectors in mixed fields

    CERN Document Server

    Klein, H

    2002-01-01

    Liquid scintillation detectors of type NE213 or BC501A are well suited and routinely used for spectrometry in mixed n-gamma-fields. Neutron- and photon-induced pulse height spectra may be simultaneously recorded making use of the n/gamma-discrimination capability based on pulse shape analysis. The light output functions for the detected secondary charged particles, i.e. electrons, positrons, protons and other charged reaction products, and the pulse height resolution function must carefully be determined. This can be done experimentally, in part via an iterative procedure by comparison with calculations. The response functions can then be reliably calculated by Monte Carlo simulations. Photon response functions calculated with the PHRESP code, which was developed on the basis of the EGS4+PRESTA program package, are in very good agreement with calibrations up to 17 MeV, both in shape and absolute scale. Similarly, neutron response functions calculated with the NRESP7 code well describe the pulse height spectra...

  19. Test of the rem-counter WENDI-II from Eberline in different energy-dispersed neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Gutermuth, F.; Radon, T.; Fehrenbacher, G.; Siekmann, R.

    2004-03-01

    The neutron rem-counter WENDI-II from Eberline was tested in high-energy particle accelerator produced neutron fields. A radioactive {sup 241}Am-Be({alpha}n) source was used as a reference. The experimentally determined responses are compared to Monte-Carlo simulations of the response function done by R. H. Olsher et al. (2000). The energy spectra of the accelerator produced neutron fields were determined employing Monte-Carlo simulations, too. According to the simulations done by C. Birattari et al. (1998) and in this work these neutron fields exhibit large contributions to the ambient dose equivalent resulting from neutrons with kinetic energy of more than 20 MeV up to a few 100 MeV. The WENDI-II detector proved to show a response of approximately 3.10{sup 9} pulses per Sievert ambient dose equivalent. Considering the experimental and statistical uncertainties the results are consistent with the assumption that the dose response of the WENDI-II reproduces quite accurately the function for the ambient dose equivalent of the ICRP 74.

  20. Test of the rem-counter WENDI-II from Eberline in different energy-dispersed neutron fields

    CERN Document Server

    Gutermuth, F; Fehrenbacher, G; Siekmann, R

    2004-01-01

    The neutron rem-counter WENDI-II from Eberline was tested in high-energy particle accelerator produced neutron fields. A radioactive 241Am-Be(α,n) source was used as a reference. The experimentally determined responses are compared to Monte-Carlo simulations of the response function done by Olsher et al. [1]. The energy spectra of the accelerator produced neutron fields were determined employing Monte-Carlo simulations, too. According to the simulations done by Birattari et al. [2] and in this work these neutron fields exhibit large contributions to the ambient dose equivalent resulting from neutrons with kinetic energy of more than 20 MeV up to a few 100 MeV. The WENDI-II detector proved to show a response of approximately 3 · 109 pulses per Sievert ambient dose equivalent. Considering the experimental and statistical uncertainties the results are consistent with the assumption that the dose response of the WENDI-II reproduces quite accurately the function for the ambient dose equivalent of the ICRP 74.

  1. Device and circuit-level performance of carbon nanotube field-effect transistor with benchmarking against a nano-MOSFET.

    Science.gov (United States)

    Tan, Michael Loong Peng; Lentaris, Georgios; Amaratunga Aj, Gehan

    2012-01-01

    The performance of a semiconducting carbon nanotube (CNT) is assessed and tabulated for parameters against those of a metal-oxide-semiconductor field-effect transistor (MOSFET). Both CNT and MOSFET models considered agree well with the trends in the available experimental data. The results obtained show that nanotubes can significantly reduce the drain-induced barrier lowering effect and subthreshold swing in silicon channel replacement while sustaining smaller channel area at higher current density. Performance metrics of both devices such as current drive strength, current on-off ratio (Ion/Ioff), energy-delay product, and power-delay product for logic gates, namely NAND and NOR, are presented. Design rules used for carbon nanotube field-effect transistors (CNTFETs) are compatible with the 45-nm MOSFET technology. The parasitics associated with interconnects are also incorporated in the model. Interconnects can affect the propagation delay in a CNTFET. Smaller length interconnects result in higher cutoff frequency. PMID:22901374

  2. Enhanced Device and Circuit-Level Performance Benchmarking of Graphene Nanoribbon Field-Effect Transistor against a Nano-MOSFET with Interconnects

    Directory of Open Access Journals (Sweden)

    Huei Chaeng Chin

    2014-01-01

    Full Text Available Comparative benchmarking of a graphene nanoribbon field-effect transistor (GNRFET and a nanoscale metal-oxide-semiconductor field-effect transistor (nano-MOSFET for applications in ultralarge-scale integration (ULSI is reported. GNRFET is found to be distinctly superior in the circuit-level architecture. The remarkable transport properties of GNR propel it into an alternative technology to circumvent the limitations imposed by the silicon-based electronics. Budding GNRFET, using the circuit-level modeling software SPICE, exhibits enriched performance for digital logic gates in 16 nm process technology. The assessment of these performance metrics includes energy-delay product (EDP and power-delay product (PDP of inverter and NOR and NAND gates, forming the building blocks for ULSI. The evaluation of EDP and PDP is carried out for an interconnect length that ranges up to 100 μm. An analysis, based on the drain and gate current-voltage (Id-Vd and Id-Vg, for subthreshold swing (SS, drain-induced barrier lowering (DIBL, and current on/off ratio for circuit implementation is given. GNRFET can overcome the short-channel effects that are prevalent in sub-100 nm Si MOSFET. GNRFET provides reduced EDP and PDP one order of magnitude that is lower than that of a MOSFET. Even though the GNRFET is energy efficient, the circuit performance of the device is limited by the interconnect capacitances.

  3. Producing Magnetar Magnetic Fields in the Merger of Binary Neutron Stars

    CERN Document Server

    Giacomazzo, Bruno; Duffell, Paul; MacFadyen, Andrew I; Perna, Rosalba

    2014-01-01

    The merger of binary neutron stars (BNSs) can lead to large amplifications of the magnetic field due to the development of turbulence and instabilities in the fluid, such as the Kelvin-Helmholtz shear instability, which drive small scale dynamo activity. In order to properly resolve such instabilities and obtain the correct magnetic field amplification, one would need to employ resolutions that are currently unfeasible in global general relativistic magnetohydrodynamic (GRMHD) simulations of BNS mergers. Here we present a subgrid model that allows global simulations to take into account the small scale amplification of the magnetic field which is caused by development of turbulence during BNS mergers. Assuming dynamo saturation, we show that magnetar-level fields ($\\sim 10^{16}\\,{\\rm G}$) can be easily reached and should therefore be expected from the merger of magnetized BNSs. The total magnetic energy can reach values up to $\\sim 10^{51}\\,{\\rm erg}$ and the post-merger remnant can therefore emit strong elec...

  4. Specification for the VERA Depletion Benchmark Suite

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kang Seog [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-12-17

    CASL-X-2015-1014-000 iii Consortium for Advanced Simulation of LWRs EXECUTIVE SUMMARY The CASL neutronics simulator MPACT is under development for the neutronics and T-H coupled simulation for the pressurized water reactor. MPACT includes the ORIGEN-API and internal depletion module to perform depletion calculations based upon neutron-material reaction and radioactive decay. It is a challenge to validate the depletion capability because of the insufficient measured data. One of the detoured methods to validate it is to perform a code-to-code comparison for benchmark problems. In this study a depletion benchmark suite has been developed and a detailed guideline has been provided to obtain meaningful computational outcomes which can be used in the validation of the MPACT depletion capability.

  5. Argonne Code Center: benchmark problem book

    International Nuclear Information System (INIS)

    This report is a supplement to the original report, published in 1968, as revised. The Benchmark Problem Book is intended to serve as a source book of solutions to mathematically well-defined problems for which either analytical or very accurate approximate solutions are known. This supplement contains problems in eight new areas: two-dimensional (R-z) reactor model; multidimensional (Hex-z) HTGR model; PWR thermal hydraulics--flow between two channels with different heat fluxes; multidimensional (x-y-z) LWR model; neutron transport in a cylindrical ''black'' rod; neutron transport in a BWR rod bundle; multidimensional (x-y-z) BWR model; and neutronic depletion benchmark problems. This supplement contains only the additional pages and those requiring modification

  6. Argonne Code Center: benchmark problem book

    Energy Technology Data Exchange (ETDEWEB)

    1977-06-01

    This report is a supplement to the original report, published in 1968, as revised. The Benchmark Problem Book is intended to serve as a source book of solutions to mathematically well-defined problems for which either analytical or very accurate approximate solutions are known. This supplement contains problems in eight new areas: two-dimensional (R-z) reactor model; multidimensional (Hex-z) HTGR model; PWR thermal hydraulics--flow between two channels with different heat fluxes; multidimensional (x-y-z) LWR model; neutron transport in a cylindrical ''black'' rod; neutron transport in a BWR rod bundle; multidimensional (x-y-z) BWR model; and neutronic depletion benchmark problems. This supplement contains only the additional pages and those requiring modification. (RWR)

  7. In vivo Observation of Tree Drought Response with Low-Field NMR and Neutron Imaging

    Science.gov (United States)

    Malone, Michael W.; Yoder, Jacob; Hunter, James F.; Espy, Michelle A.; Dickman, Lee T.; Nelson, Ron O.; Vogel, Sven C.; Sandin, Henrik J.; Sevanto, Sanna

    2016-01-01

    Using a simple low-field NMR system, we monitored water content in a living tree in a greenhouse over 2 months. By continuously running the system, we observed changes in tree water content on a scale of half an hour. The data showed a diurnal change in water content consistent both with previous NMR and biological observations. Neutron imaging experiments show that our NMR signal is primarily due to water being rapidly transported through the plant, and not to other sources of hydrogen, such as water in cytoplasm, or water in cell walls. After accounting for the role of temperature in the observed NMR signal, we demonstrate a change in the diurnal signal behavior due to simulated drought conditions for the tree. These results illustrate the utility of our system to perform noninvasive measurements of tree water content outside of a temperature controlled environment. PMID:27200037

  8. In vivo observation of tree drought response with low-field NMR and neutron imaging

    Directory of Open Access Journals (Sweden)

    Michael W. Malone

    2016-05-01

    Full Text Available Using a simple low-field NMR system, we monitored water content in a livingtree in a greenhouse over two months. By continuously running thesystem, we observed changes in tree water content on a scale of halfan hour. The data showed a diurnal change in water content consistentboth with previous NMR and biological observations. Neutron imaging experiments showthat our NMR signal is primarily due to water being rapidly transported through the plant, and not to other sources of hydrogen, such as water in cytoplasm, or water in cell walls. After accountingfor the role of temperature in the observed NMR signal, we demonstratea change in the diurnal signal behavior due to simulated drought conditionsfor the tree. These results illustrate the utility of our system toperform noninvasive measurements of tree water content outside of a temperature controlled environment.

  9. In vivo Observation of Tree Drought Response with Low-Field NMR and Neutron Imaging.

    Science.gov (United States)

    Malone, Michael W; Yoder, Jacob; Hunter, James F; Espy, Michelle A; Dickman, Lee T; Nelson, Ron O; Vogel, Sven C; Sandin, Henrik J; Sevanto, Sanna

    2016-01-01

    Using a simple low-field NMR system, we monitored water content in a living tree in a greenhouse over 2 months. By continuously running the system, we observed changes in tree water content on a scale of half an hour. The data showed a diurnal change in water content consistent both with previous NMR and biological observations. Neutron imaging experiments show that our NMR signal is primarily due to water being rapidly transported through the plant, and not to other sources of hydrogen, such as water in cytoplasm, or water in cell walls. After accounting for the role of temperature in the observed NMR signal, we demonstrate a change in the diurnal signal behavior due to simulated drought conditions for the tree. These results illustrate the utility of our system to perform noninvasive measurements of tree water content outside of a temperature controlled environment. PMID:27200037

  10. Effect of superstrong magnetic field on electron screening at the crusts of neutron stars

    International Nuclear Information System (INIS)

    The influences of electron screening (ES) and electron energy correction (EEC) are investigated by superstrong magnetic field (SMF). We also discuss in detail the discrepant factor between our results and those of Fushiki, Gudmundsson and Pethick (FGP) in SMF. The results show that SMF has only a slight effect on ES when B 9 T on the surfaces of most neutron stars. Whereas for some magnetars, SMF influence ES greatly when B > 109 T. For instance, due to SMF the ES potential may be increased about 23.6% and the EEC may be increased about 4 orders of magnitude at ρ/μe = 1.0 × 106 mol/cm3 and T9 = 1. On the other hand, the discrepant factor shows that our results are in good agreement with FGP's when B 9 T. But the difference will be increased with increasing SMF. (geophysics, astronomy and astrophysics)

  11. Pulse-shape discrimination of the new plastic scintillators in neutron-gamma mixed field using fast digitizer card

    Science.gov (United States)

    Jančář, A.; Kopecký, Z.; Dressler, J.; Veškrna, M.; Matěj, Z.; Granja, C.; Solar, M.

    2015-11-01

    Recently invented plastic scintillator EJ-299-33 enables pulse-shape discrimination (PSD) and thus measurement of neutron and photon spectra in mixed fields. In this work we compare the PSD properties of EJ-299-33 plastic and the well-known NE-213 liquid scintillator in monoenergetic neutron fields generated by the Van de Graaff accelerator using the 3H(d, n)4He reaction. Pulses from the scintillators are processed by a newly developed digital measuring system employing the fast digitizer card. This card contains two AD converters connected to the measuring computer via 10 Gbps optical ethernet. The converters operate with a resolution of 12 bits and have two differential inputs with a sampling frequency 1 GHz. The resulting digital channels with different gains are merged into one composite channel with a higher digital resolution in a wide dynamic range of energies. Neutron signals are fully discriminated from gamma signals. Results are presented.

  12. Multilayer detector for operative estimation of spectral composition of neutron fields

    CERN Document Server

    Dedenko, G L; Kaplun, A A; Kolesnikov, S V; Samosadnyj, A V; Samosadnyj, V T

    2002-01-01

    Paper describes measuring and control equipment to detect and to identify neutron sources. The equipment comprises two multilayer detectors based on sup 3 He-counters of slow neutron and poly ethylene moderator of fast neutrons, as well as, intensifiers-signal shapers, power multichannel intensifies, power unit, 8-bit microprocessor base information acquisition and processing system. Paper contains the results of measurements of energy dependence of sensitivity of neutron recording by detector layers with application of monoenergetic neutron fluxes. Difference of the experimental data and the Monte Carlo method base calculation results is 10% maximum

  13. Benchmarking: A tool to enhance performance

    Energy Technology Data Exchange (ETDEWEB)

    Munro, J.F. [Oak Ridge National Lab., TN (United States); Kristal, J. [USDOE Assistant Secretary for Environmental Management, Washington, DC (United States); Thompson, G.; Johnson, T. [Los Alamos National Lab., NM (United States)

    1996-12-31

    The Office of Environmental Management is bringing Headquarters and the Field together to implement process improvements throughout the Complex through a systematic process of organizational learning called benchmarking. Simply stated, benchmarking is a process of continuously comparing and measuring practices, processes, or methodologies with those of other private and public organizations. The EM benchmarking program, which began as the result of a recommendation from Xerox Corporation, is building trust and removing barriers to performance enhancement across the DOE organization. The EM benchmarking program is designed to be field-centered with Headquarters providing facilitatory and integrative functions on an ``as needed`` basis. One of the main goals of the program is to assist Field Offices and their associated M&O/M&I contractors develop the capabilities to do benchmarking for themselves. In this regard, a central precept is that in order to realize tangible performance benefits, program managers and staff -- the ones closest to the work - must take ownership of the studies. This avoids the ``check the box`` mentality associated with some third party studies. This workshop will provide participants with a basic level of understanding why the EM benchmarking team was developed and the nature and scope of its mission. Participants will also begin to understand the types of study levels and the particular methodology the EM benchmarking team is using to conduct studies. The EM benchmarking team will also encourage discussion on ways that DOE (both Headquarters and the Field) can team with its M&O/M&I contractors to conduct additional benchmarking studies. This ``introduction to benchmarking`` is intended to create a desire to know more and a greater appreciation of how benchmarking processes could be creatively employed to enhance performance.

  14. The Linked Data Benchmark Council Project

    NARCIS (Netherlands)

    Boncz, P.A.; Fundulaki, I.; Gubichev, A.; Larriba-Pey, J.; Neumann, T.

    2013-01-01

    Despite the fast growth and increasing popularity, the broad field of RDF and Graph database systems lacks an independent authority for developing benchmarks, and for neutrally assessing benchmark results through industry-strength auditing which would allow to quantify and compare the performance of

  15. Benchmark Data Set for Wheat Growth Models: Field Experiments and AgMIP Multi-Model Simulations.

    Science.gov (United States)

    Asseng, S.; Ewert, F.; Martre, P.; Rosenzweig, C.; Jones, J. W.; Hatfield, J. L.; Ruane, A. C.; Boote, K. J.; Thorburn, P.J.; Rotter, R. P.

    2015-01-01

    The data set includes a current representative management treatment from detailed, quality-tested sentinel field experiments with wheat from four contrasting environments including Australia, The Netherlands, India and Argentina. Measurements include local daily climate data (solar radiation, maximum and minimum temperature, precipitation, surface wind, dew point temperature, relative humidity, and vapor pressure), soil characteristics, frequent growth, nitrogen in crop and soil, crop and soil water and yield components. Simulations include results from 27 wheat models and a sensitivity analysis with 26 models and 30 years (1981-2010) for each location, for elevated atmospheric CO2 and temperature changes, a heat stress sensitivity analysis at anthesis, and a sensitivity analysis with soil and crop management variations and a Global Climate Model end-century scenario.

  16. Aquatic Life Benchmarks

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Aquatic Life Benchmarks is an EPA-developed set of criteria for freshwater species. These benchmarks are based on toxicity values reviewed by EPA and used in...

  17. Magnetic neutron scattering resonance of high-¤Tc¤ superconductors in external magnetic fields: An SO(5) study

    DEFF Research Database (Denmark)

    Mortensen, Asger; Rønnow, Henrik Moodysson; Bruus, Henrik;

    2000-01-01

    The magnetic resonance at 41 meV observed in neutron scattering studies of YBa2Cu3O7 holds a key position in the understanding of high-T-c, superconductivity. Within the SO(5) model for superconductivity and antiferromagnetism, we have calculated the effect of an applied magnetic field on the neu...

  18. Dipolar structures in magnetite ferrofluids studied with small-angle neutron scattering with and without applied magnetic field

    NARCIS (Netherlands)

    Klokkenburg, M.; Erne, B.H.; Wiedenmann, A.; Petukhov, A.V.; Philipse, A.P.

    2007-01-01

    Field-induced structure formation in a ferrofluid with well-defined magnetite nanoparticles with a permanent magnetic dipole moment was studied with small-angle neutron scattering (SANS) as a function of the magnetic interactions. The interactions were tuned by adjusting the size of the well-defined

  19. Neutron-photon mixed field dosimetry by TLD-700 glow curve analysis and its implementation in dose monitoring for Boron Neutron Capture Therapy (BNCT) treatments

    International Nuclear Information System (INIS)

    BNCT is a cancerous cells selective, non-conventional radiotherapy modality to treat malignant tumors such as glioblastoma, melanoma and recurrent head and neck cancer. It consists of a two-step procedure: first, the patient is injected with a tumor localizing drug containing a non-radioactive isotope (Boron-10) with high slow neutron capture cross-section. In a second step, the patient is irradiated with neutrons, which are absorbed by the Boron-10 agent with the subsequently nuclear reaction B- 10(n,a)Li-7, thereby resulting in dose at cellular level due to the high-Let particles. The neutron fields suitable for BNCT are characterized by high neutron fluxes and low gamma dose. Determination of each component is not an easy task, especially when the volume of measurement is quite small or inaccessible for a miniature ionization chamber, for example. A method of measuring the photon and slow neutron dose(mainly by N-14 and B-10) from the glow curve (GC) analysis of a single 7LiF thermoluminescence detector is evaluated. This method was suggested by the group headed by Dr. Grazia Gambarini. The dosemeters used were TLD-600 (6LiF:Mg,Ti with 95.6% 6Li) and TLD-700 (7LiF:Mg,Ti with 99.9% 7LiF) from Harshaw. Photon dose measurement using the GC analysis method with TLD-700 in mixed fields requires the relation of the two main peaks of a TLD-600 GC shape obtained from an exposition to the same neutron field, and a photon calibrated GC with TLD-700. The requirements for slow neutron dose measurements are similar. In order to properly apply the GC analysis method at the Ra-6 Research Reactor BNCT facility, measurements were carried out in a standard water phantom, fully characterized on the BNCT beam by conventional techniques (activation detectors and paired ionization chambers technique). Next, the method was implemented in whole body dose monitoring of a patient undergoing a BNCT treatment, using a Bo MAb (Bottle Manikin Absorption) phantom, with representative

  20. Neutron-photon mixed field dosimetry by TLD-700 glow curve analysis and its implementation in dose monitoring for Boron Neutron Capture Therapy (BNCT) treatments

    Energy Technology Data Exchange (ETDEWEB)

    Boggio, E. F.; Longhino, J. M. [Centro Atomico Bariloche, Departamento de Fisica de Reactores y Radiaciones / CNEA, Av. E. Bustillo Km 9.5, R8402AGP San Carlos de Bariloche (Argentina); Andres, P. A., E-mail: efboggio@cab.cnea.gov.ar [Centro Atomico Bariloche, Division Proteccion Radiologica / CNEA, Av. E. Bustillo Km 9.5, R8402AGP San Carlos de Bariloche (Argentina)

    2015-10-15

    BNCT is a cancerous cells selective, non-conventional radiotherapy modality to treat malignant tumors such as glioblastoma, melanoma and recurrent head and neck cancer. It consists of a two-step procedure: first, the patient is injected with a tumor localizing drug containing a non-radioactive isotope (Boron-10) with high slow neutron capture cross-section. In a second step, the patient is irradiated with neutrons, which are absorbed by the Boron-10 agent with the subsequently nuclear reaction B- 10(n,a)Li-7, thereby resulting in dose at cellular level due to the high-Let particles. The neutron fields suitable for BNCT are characterized by high neutron fluxes and low gamma dose. Determination of each component is not an easy task, especially when the volume of measurement is quite small or inaccessible for a miniature ionization chamber, for example. A method of measuring the photon and slow neutron dose(mainly by N-14 and B-10) from the glow curve (GC) analysis of a single {sup 7}LiF thermoluminescence detector is evaluated. This method was suggested by the group headed by Dr. Grazia Gambarini. The dosemeters used were TLD-600 ({sup 6}LiF:Mg,Ti with 95.6% {sup 6}Li) and TLD-700 ({sup 7}LiF:Mg,Ti with 99.9% {sup 7}LiF) from Harshaw. Photon dose measurement using the GC analysis method with TLD-700 in mixed fields requires the relation of the two main peaks of a TLD-600 GC shape obtained from an exposition to the same neutron field, and a photon calibrated GC with TLD-700. The requirements for slow neutron dose measurements are similar. In order to properly apply the GC analysis method at the Ra-6 Research Reactor BNCT facility, measurements were carried out in a standard water phantom, fully characterized on the BNCT beam by conventional techniques (activation detectors and paired ionization chambers technique). Next, the method was implemented in whole body dose monitoring of a patient undergoing a BNCT treatment, using a Bo MAb (Bottle Manikin Absorption) phantom

  1. A benchmark study of the two-dimensional Hubbard model with auxiliary-field quantum Monte Carlo method

    CERN Document Server

    Qin, Mingpu; Zhang, Shiwei

    2016-01-01

    Ground state properties of the Hubbard model on a two-dimensional square lattice are studied by the auxiliary-field quantum Monte Carlo method. Accurate results for energy, double occupancy, effective hopping, magnetization, and momentum distribution are calculated for interaction strengths of U/t from 2 to 8, for a range of densities including half-filling and n = 0.3, 0.5, 0.6, 0.75, and 0.875. At half-filling, the results are numerically exact. Away from half-filling, the constrained path Monte Carlo method is employed to control the sign problem. Our results are obtained with several advances in the computational algorithm, which are described in detail. We discuss the advantages of generalized Hartree-Fock trial wave functions and its connection to pairing wave functions, as well as the interplay with different forms of Hubbard-Stratonovich decompositions. We study the use of different twist angle sets when applying the twist averaged boundary conditions. We propose the use of quasi-random sequences, whi...

  2. Benchmark ab initio thermochemistry of the isomers of diimide, $N_{2}H_2$, using accurate computed structures and anharmonic force fields

    CERN Document Server

    Martin, J M L; Martin, Jan M.L.; Taylor, Peter R.

    1999-01-01

    A benchmark ab initio study on the thermochemistry of the trans-HNNH, cis-HNNH, and H$_2$NN isomers of diazene has been carried out using the CCSD(T) coupled cluster method, basis sets as large as $[7s6p5d4f3g2h/5s4p3d2f1g]$, and extrapolations towards the 1-particle basis set limit. The effects on inner-shell correlation and of anharmonicity in the zero-point energy were taken into account: accurate geometries and anharmonic force fields were thus obtained as by-products. Our best computed $\\Delta H^\\circ_{f,0}$ for trans-HNNH, 49.2 \\pm 0.3 kcal/mol, is in very good agreement with a recent experimental lower limit of 48.8 \\pm 0.5 kcal/mol. CCSD(T) basis set limit values for the isomerization energies at 0 K are 5.2 \\pm 0.2 kcal/mol (cis-trans) and 24.1 \\pm 0.2 kcal/mol (iso-trans). Our best computed geometry for trans-HNNH, $r_e$(NN)=1.2468 Å, $r_e$(NH)=1.0283 Å, and rotational constants of trans-HNNH to within better than 0.1 %. The rotation-vibration spectra of both cis-HNNH and H$_2$NN are dominated by ...

  3. Preliminary study about frequencies of unstable chromosome alterations induced by gamma beam and neutron-gamma mixed field

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Mariana E.; Souza, Priscilla L.G.; Brandao, Jose Odinilson de C.; Santos, Joelan A.L.; Vilela, Eudice C.; Lima, Fabiana F. [Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Calixto, Merilane S.; Santos, Neide [Universidade Federal de Pernanmbuco (CCB/UFPE), Recife, PE (Brazil). Centro de Ciencias Biologicas. Dept. de Genetica

    2011-07-01

    The estimate on approximate dose in exposed individual can be made through conventional cytogenetic analysis of dicentric, this technique has been used to support physical dosimetry. It is important to estimate the absorbed dose in case of accidents with the aim of developing an appropriate treatment and biological dosimetry can be very useful in case where the dosimetry is unavailable. Exposure to gamma and neutron radiation leads to the same biological effects such as chromosomal alterations and cancer. However, neutrons cause more genetic damage, such as mutation or more structural damage, such as chromosome alterations. The aim of research is to compare frequencies of unstable chromosome alterations induced by a gamma beam with those from neutron-gamma mixed field. Two blood samples were obtained from one healthy donor and irradiated at different sources. The first sample was exposed to mixed field neutron-gamma sources {sup 241}AmBe at the Neutron Calibration Laboratory (NCL - CRCN/NE - PE - Brazil) and the second one was exposed to {sup 137}Cs gamma rays at {sup 137}Cs Laboratory (CRCN/NE - PE - Brazil), both exposures resulting in an absorbed dose of 0.66Gy. Mitotic metaphase cells were obtained by lymphocyte culture for chromosomal analysis and slides were stained with Giemsa 5%. These preliminary results showed a similarity in associated dicentrics frequency per cell (0.041 and 0.048) after {sup 137}Cs and {sup 241}AmBe sources irradiations, respectively. However, it was not observed centric rings frequency per cell (0.0 and 0.027). This study will be continue to verify the frequencies of unstable chromosome alterations induced by only gamma beam and neutron-gamma mixed field. (author)

  4. Study on the response of IFMIF fission chambers to mixed neutron-gamma fields: PH-2 experimental tests

    OpenAIRE

    Rapisarda, D; Vermeeren, L.; Garcia, A; Cabellos de Francisco, Oscar Luis; GARCIA, J.M.; Ibarra, A.; Gómez Ros, J.M.; MOTA, F.; Casal, N.; Queral, V.

    2011-01-01

    The engineering design of fissionchambers as on-line radiation detectors for IFMIF is being performed in the framework of the IFMIF-EVEDA works. In this paper the results of the experiments performed in the BR2 reactor during the phase-2 of the foreseen validation activities are addressed. Two detectors have been tested in a mixedneutron-gamma field with high neutron fluence and gamma absorbed dose rates, comparable with the expected values in the HFTM in IFMIF. Since the neutron spectra in a...

  5. A field calibration of neutron moisture meter and gamma ray density probe in a duplex soil profile

    International Nuclear Information System (INIS)

    Field calibrations of two neutron moisture meters and a gamma ray density probe were obtained for the two layers of a duplex soil, sand over clay, in south east South Australia. The technique involved destructive sampling around access tubes set out in a grid pattern in a pine forest. The density probe was found to have a single calibration for both soil layers. The neutron moisture meters yielded calibrations which were different for the sand and clay layers. It is shown that errors associated with the use of each curve decrease when a correction is made for the dry bulk density of the soil layer

  6. RISKIND verification and benchmark comparisons

    International Nuclear Information System (INIS)

    This report presents verification calculations and benchmark comparisons for RISKIND, a computer code designed to estimate potential radiological consequences and health risks to individuals and the population from exposures associated with the transportation of spent nuclear fuel and other radioactive materials. Spreadsheet calculations were performed to verify the proper operation of the major options and calculational steps in RISKIND. The program is unique in that it combines a variety of well-established models into a comprehensive treatment for assessing risks from the transportation of radioactive materials. Benchmark comparisons with other validated codes that incorporate similar models were also performed. For instance, the external gamma and neutron dose rate curves for a shipping package estimated by RISKIND were compared with those estimated by using the RADTRAN 4 code and NUREG-0170 methodology. Atmospheric dispersion of released material and dose estimates from the GENII and CAP88-PC codes. Verification results have shown the program to be performing its intended function correctly. The benchmark results indicate that the predictions made by RISKIND are within acceptable limits when compared with predictions from similar existing models

  7. Dipolar structures in magnetite ferrofluids studied with small-angle neutron scattering with and without applied magnetic field

    OpenAIRE

    Klokkenburg, M.; Erne, B.H.; Wiedenmann, A.; Petukhov, A.V.; Philipse, A. P.

    2007-01-01

    Field-induced structure formation in a ferrofluid with well-defined magnetite nanoparticles with a permanent magnetic dipole moment was studied with small-angle neutron scattering (SANS) as a function of the magnetic interactions. The interactions were tuned by adjusting the size of the well-defined, single-magnetic-domain magnetite (Fe3O4) particles and by applying an external magnetic field. For decreasing particle dipole moments, the data show a progressive distortion of the hexagonal symm...

  8. Pilot study for the implantation of a high-energy neutrons field; Estudo piloto para a implantacao de um campo de neutrons de alta energia

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Jose Julio de O.; Mendes, Adriane C.; Federico, Claudio A.; Passaro, Angelo; Gaspar, Felipe de B., E-mail: jjfilos@hotmail.com, E-mail: adriane@ieav.cta.br, E-mail: claudiofederico@ieav.cta.br, E-mail: angelo@ieav.cta.br, E-mail: fbgaspar@ieav.cta.br [Instituto de Estudos Avancados (IEAv/DCTA), Sao Jose dos Campos, SP (Brazil); Pazianotto, Mauricio T., E-mail: mpazianotto@gmail.com [Instituto Tecnologico de Aeronautica (ITA/DCTA), Sao Jose dos Campos, SP (Brazil)

    2013-07-01

    In this work a theoretical study is presented for the implementation of a high-energy neutron field (14.1 MeV) produced by a neutron generator type DT (deuterium-tritium), to be installed in the premises of the Laboratorio de Radiacoes Ionizantes (LRI) of the Instituto de Estudos Avancados (IEAv). This evaluation was performed by means of computer simulation by Monte Carlo method, using the computer code MCNP5 (Monte Carlo N-Particle). The neutron spectra were simulated computationally for pre-selected points of the installation, allowing to estimate the beam quality in the positions provided for use of the direct beam. These simulations also allow assist the basement of a project to install the consistent D-T generator with the guidelines for radiation protection and radiation safety standards determined by the Comissao Nacional de Energia Nuclear (CNEN), by estimating the dose rates provided in accessible points to Individuals Occupationally Exposed (IOE) in the facility. The computational determination of spectra, fluxes and doses produced in different positions previously selected within and outside the laboratory, will serve as guidance from previous studies for the future installation of this generator in the physical facilities of the LRI.

  9. The use of albedo neutron dosemeters for the measurement of low doses in mixed photon neutron radiation fields at transport casks for high active waste

    International Nuclear Information System (INIS)

    Radiation exposure of the police forces accompanying transports of spent fuel elements and high-active waste form reprocessing (HAW) is determined by means of albedo dosemeters. The official dosimetry services use this type of dosemeter to mesure the personal dose in mixed gamma/neutron radiation fields above all for routine monitoring of workers occupationally exposed to radiation. The present report describes the detailed set-up and functioning of the albedo dosemeter, the process of obtaining the photon and neutron personal dose from the detector indications as well as the determination of the detection limit of the total personal dose of the albedo dosemeter according to the methods specified in the valid standards. Determination of the detection limit is based on the experience gained during previous transports, on measurements performed at transport casks, on results of type tests at PTB (Federal Physical and Technical Authority), on the measurement uncertainties obtained from the annual intercomparison measurements of the PTB as well as on the test irradiation specially performed in the range of small neutron and photon doses under laboratory conditions. For the dosimetry systems of the dosimetry services and the specific transport conditions, a reference level of 100 μSv was specified with regard to the dose detection limit. (orig.)

  10. Development of monitoring method of spatial neutron distribution in neutrons–gamma rays mixed field using imaging plate for NCT—Depression of the field

    International Nuclear Information System (INIS)

    The degree of depression in the neutron field caused by neutron absorption in the materials of an imaging plate (IP) was investigated using MCNP-4C. Consequently, the IP doped with Gd, which reproduced the distribution of 157Gd(n,γ)158Gd reaction rate in the previous study, depresses the relative distribution by about 50%. The depression for the IP in which Gd is replaced with similar amount of B atoms was estimated to be about 10%. The signal intensity for this IP is estimated to be at a similar level with that for Gd-doped IP.

  11. ESR investigation of joint use of dentin and tooth enamel to estimate photon and neutron dose components of a mixed field

    International Nuclear Information System (INIS)

    In the case of mixed photon and neutron field, estimation of photon and neutron dose components from the ESR signal of tooth enamel alone is impossible. To differentiate neutron and photon components using the method described in ICRU 26 for twin chambers, enamel and dentin sensitivities to photon and to neutron were investigated. Enamel and dentin relative sensitivities were, respectively, estimated at 0.03 ± 0.02 and 0.14 ± 0.10 for fission neutrons. Basing on this result, calculation of neutron and photon doses was performed in realistic case of criticality accident. Estimation of neutron and photon dose components was found in good agreement with reference dosimetry. (authors)

  12. Benchmarking semantic web technology

    CERN Document Server

    García-Castro, R

    2009-01-01

    This book addresses the problem of benchmarking Semantic Web Technologies; first, from a methodological point of view, proposing a general methodology to follow in benchmarking activities over Semantic Web Technologies and, second, from a practical point of view, presenting two international benchmarking activities that involved benchmarking the interoperability of Semantic Web technologies using RDF(S) as the interchange language in one activity and OWL in the other.The book presents in detail how the different resources needed for these interoperability benchmarking activities were defined:

  13. Measurement and calculations of long-lived radionuclide activity forming in the fast neutron field in some ITER construction steels

    Energy Technology Data Exchange (ETDEWEB)

    Pohorecki, W., E-mail: poho@agh.edu.pl [AGH University of Science and Technology, Faculty of Energy and Fuels, Al. Mickiewicza 30, 30-059 Krakow (Poland); Jodłowski, P. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Al. Mickiewicza 30, 30-059 Krakow (Poland); Pytel, K.; Prokopowicz, R. [National Centre for Nuclear Research, ul. Sołtana 7, 05-400 Otwock-Świerk (Poland)

    2014-10-15

    Highlights: • Measurement and calculations of long-lived gamma-emitting radionuclide activity forming in the fission reactor fast neutron field were done, in some ITER construction steels. • The neutron flux density was measured by means of activation foil method and unfolding technique. • Activity calculations were done by means of FISPACT-II code using the activation libraries EAF-2010 and TALYS-2011. • The activity measurements were done by means of gamma-ray spectrometry. - Abstract: Measurement and calculations of long-lived gamma-emitting radionuclide activity forming in the fission reactor fast neutron field were done, for some ITER construction steels. The activation was conducted in fast neutron irradiation channel of the MARIA research fission reactor (Poland). The dimensions of steel samples were 10 mm × 10 mm × 1 mm and mass was approximately 0.8 g. The neutron flux density was measured by means of activation foil method and unfolding technique; fraction of neutrons above 1 keV was 95%. The activation lasted 242 h and cooling took 100 days; the mean neutron flux density was 2.9E12 n/(cm{sup 2} s) (neutrons above 500 keV are 53% of total) whereas total fluency 2.53E18 cm{sup −2}. The activity measurements were done by means of gamma-ray spectrometry. Activity calculations were done by means of FISPACT-II code using the activation libraries EAF-2010 and TENDL-2011 and experimentally determined neutron flux. Measured activity of long-lived gamma emitting radionuclides was, in average, about 6.3 MBq/g 100 days after activation; the dominant radionuclides were {sup 58}Co and {sup 54}Mn (about 81% and 14% of total activity respectively). The C/E ratio differs for particular radionuclides and is in the range 0.86–0.92 for {sup 51}Cr, 0.93–1.21 for {sup 54}Mn, 0.77–0.98 for {sup 57}Co, 0.91–1.21 for {sup 58}Co, 1.17–1.27 for {sup 59}Fe, and 1.75–2.44 for {sup 60}Co.

  14. Measurement and calculations of long-lived radionuclide activity forming in the fast neutron field in some ITER construction steels

    International Nuclear Information System (INIS)

    Highlights: • Measurement and calculations of long-lived gamma-emitting radionuclide activity forming in the fission reactor fast neutron field were done, in some ITER construction steels. • The neutron flux density was measured by means of activation foil method and unfolding technique. • Activity calculations were done by means of FISPACT-II code using the activation libraries EAF-2010 and TALYS-2011. • The activity measurements were done by means of gamma-ray spectrometry. - Abstract: Measurement and calculations of long-lived gamma-emitting radionuclide activity forming in the fission reactor fast neutron field were done, for some ITER construction steels. The activation was conducted in fast neutron irradiation channel of the MARIA research fission reactor (Poland). The dimensions of steel samples were 10 mm × 10 mm × 1 mm and mass was approximately 0.8 g. The neutron flux density was measured by means of activation foil method and unfolding technique; fraction of neutrons above 1 keV was 95%. The activation lasted 242 h and cooling took 100 days; the mean neutron flux density was 2.9E12 n/(cm2 s) (neutrons above 500 keV are 53% of total) whereas total fluency 2.53E18 cm−2. The activity measurements were done by means of gamma-ray spectrometry. Activity calculations were done by means of FISPACT-II code using the activation libraries EAF-2010 and TENDL-2011 and experimentally determined neutron flux. Measured activity of long-lived gamma emitting radionuclides was, in average, about 6.3 MBq/g 100 days after activation; the dominant radionuclides were 58Co and 54Mn (about 81% and 14% of total activity respectively). The C/E ratio differs for particular radionuclides and is in the range 0.86–0.92 for 51Cr, 0.93–1.21 for 54Mn, 0.77–0.98 for 57Co, 0.91–1.21 for 58Co, 1.17–1.27 for 59Fe, and 1.75–2.44 for 60Co

  15. Neutron field characterization in the installation for BNCT study in the IEA-R1 reactor; Caracterizacao do campo de neutrons na instalacao para estudo em BNCT no reator IEA-R1

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro Junior, Valdeci

    2008-07-01

    This work aims to characterize the mixed neutron and gamma field, in the sample irradiation position, in a research installation for Boron Neutron Capture Therapy (BNCT), in the IPEN IEA-R1 reactor. The BNCT technique has been studied as a safe and selective option in the treatment of resistant cancerigenous tumors or considered non-curable by the conventional techniques, for example, the Glioblastoma Multiform - a brain cancerigenous tumor. Neutron flux measurements were carried out: thermal, resonance and fast, as well as neutron and gamma rays doses, in the sample position, using activation foils detectors and thermoluminescent dosimeters. For the determination of the neutron spectrum and intensity, a set of different threshold activation foils and gold foils covered and uncovered with cadmium irradiated in the installation was used, analyzed by a high Pure Germanium semiconductor detector, coupled to an electronic system suitable for gamma spectrometry. The results were processed with the SAND-BP code. The doses due to gamma and neutron rays were determined using thermoluminescent dosimeters TLD 400 and TLD 700 sensitive to gamma and TLD 600, sensitive to neutrons. The TLDs were selected and used for obtaining the calibration curves - dosimeter answer versus dose - from each of the TLD three types, which were necessary to calculate the doses due to neutron and gamma, in the sample position. The radiation field, in the sample irradiation position, was characterized flux for thermal neutrons of 1.39.10{sup 8} {+-} 0,12.10{sup 8} n/cm{sup 2}s the doses due to thermal neutrons are three times higher than those due to gamma radiation and confirm the reproducibility and consistency of the experimental findings obtained. Considering these results, the neutron field and gamma radiation showed to be appropriated for research in BNCT. (author)

  16. Characterisation of mixed neutron-photon workplace fields at nuclear facilities by spectrometry (energy and direction) within the EVIDOS project

    International Nuclear Information System (INIS)

    Within the EC project EVIDOS, 17 different mixed neutron-photon workplace fields at nuclear facilities (boiling water reactor, pressurised water reactor, research reactor, fuel processing, storage of spent fuel) were characterised using conventional Bonner sphere spectrometry and newly developed direction spectrometers. The results of the analysis, using Bayesian parameter estimation methods and different unfolding codes, some of them especially adapted to simultaneously unfold energy and direction distributions of the neutron fluence, showed that neutron spectra differed strongly at the different places, both in energy and direction distribution. The implication of the results for the determination of reference values for radiation protection quantities (ambient dose equivalent, personal dose equivalent and effective dose) and the related uncertainties are discussed. (authors)

  17. Evaluation of the spectrometric and dose characteristics of neutron fields inside the Russian segment of the ISS by fission detectors

    Science.gov (United States)

    Shurshakov, V. A.; Vorob'ev, I. B.; Nikolaev, V. A.; Lyagushin, V. I.; Akatov, Yu. A.; Kushin, V. V.

    2016-03-01

    The results of measuring the dose and the energy spectrum of neutrons inside the Russian segment of the International Space Station (ISS) from March 21 until November 10, 2002 are presented. Statistically reliable results of measurement are obtained by using thorium- and uranium-based fission detectors with cadmium and boron filters. The kits of the detectors with filters have been arranged in three compartments within assembled passive detectors in the BRADOS space experiment. The ambient dose rate H* = 139 μSv day and an energy spectrum of neutrons in the range of 10-2-104 MeV is obtained as average for the ISS compartments and is compared with the measurements carried out inside the compartments of the MIR space station. Recommendations on how to improve the procedure for using the fission detectors to measure the characteristics of neutron fields inside the compartments of space stations are formulated.

  18. Study of particle size distribution and formation mechanism of radioactive aerosols generated in high-energy neutron fields

    CERN Document Server

    Endo, A; Noguchi, H; Tanaka, S; Iida, T; Furuichi, S; Kanda, Y; Oki, Y

    2003-01-01

    The size distributions of sup 3 sup 8 Cl, sup 3 sup 9 Cl, sup 8 sup 2 Br and sup 8 sup 4 Br aerosols generated by irradiations of argon and krypton gases containing di-octyl phthalate (DOP) aerosols with 45 MeV and 65 MeV quasi-monoenergetic neutrons were measured in order to study the formation mechanism of radioactive particles in high energy radiation fields. The effects of the size distribution of the radioactive aerosols on the size of the added DOP aerosols, the energy of the neutrons and the kinds of nuclides were studied. The observed size distributions of the radioactive particles were explained by attachment of the radioactive atoms generated by the neutron-induced reactions to the DOP aerosols. (author)

  19. Benchmarking in University Toolbox

    Directory of Open Access Journals (Sweden)

    Katarzyna Kuźmicz

    2015-06-01

    Full Text Available In the face of global competition and rising challenges that higher education institutions (HEIs meet, it is imperative to increase innovativeness and efficiency of their management. Benchmarking can be the appropriate tool to search for a point of reference necessary to assess institution’s competitive position and learn from the best in order to improve. The primary purpose of the paper is to present in-depth analysis of benchmarking application in HEIs worldwide. The study involves indicating premises of using benchmarking in HEIs. It also contains detailed examination of types, approaches and scope of benchmarking initiatives. The thorough insight of benchmarking applications enabled developing classification of benchmarking undertakings in HEIs. The paper includes review of the most recent benchmarking projects and relating them to the classification according to the elaborated criteria (geographical range, scope, type of data, subject, support and continuity. The presented examples were chosen in order to exemplify different approaches to benchmarking in higher education setting. The study was performed on the basis of the published reports from benchmarking projects, scientific literature and the experience of the author from the active participation in benchmarking projects. The paper concludes with recommendations for university managers undertaking benchmarking, derived on the basis of the conducted analysis.

  20. Effect of Magnetic Field on the Phase Transition from Nuclear Matter to Quark Matter during Proto-Neutron Star Evolution

    CERN Document Server

    Gupta, V K; Singh, S; Anand, J D; Gupta, Asha

    2002-01-01

    We have studied phase transition from hadron matter to quark matter in the presence of high magnetic fields incorporating the trapped electron neutrinos at finite temperatures. We have used the density dependent quark mass (DDQM) model for the quark phase while the hadron phase is treated in the frame-work of relativistic mean field theory. It is seen that the nuclear energy at phase transition decreases with both magnetic field and temperature. A brief discussion of the effect of magnetic field in supernova explosions and proto-neutron star evolution is given.

  1. Risk of Developing Second Cancer From Neutron Dose in Proton Therapy as Function of Field Characteristics, Organ, and Patient Age

    International Nuclear Information System (INIS)

    Purpose: To estimate the risk of a second malignancy after treatment of a primary brain cancer using passive scattered proton beam therapy. The focus was on the cancer risk caused by neutrons outside the treatment volume and the dependency on the patient's age. Methods and Materials: Organ-specific neutron-equivalent doses previously calculated for eight different proton therapy brain fields were considered. Organ-specific models were applied to assess the risk of developing solid cancers and leukemia. Results: The main contributors (>80%) to the neutron-induced risk are neutrons generated in the treatment head. Treatment volume can influence the risk by up to a factor of ∼2. Young patients are subject to significantly greater risks than are adult patients because of the geometric differences and age dependency of the risk models. Breast cancer should be the main concern for females. For males, the risks of lung cancer, leukemia, and thyroid cancer were significant for pediatric patients. In contrast, leukemia was the leading risk for an adult. Most lifetime risks were <1% (70-Gy treatment). The only exceptions were breast, thyroid, and lung cancer for females. For female thyroid cancer, the treatment risk can exceed the baseline risk. Conclusion: The risk of developing a second malignancy from neutrons from proton beam therapy of a brain lesion is small (i.e., presumably outweighed by the therapeutic benefit) but not negligible (i.e., potentially greater than the baseline risk). The patient's age at treatment plays a major role

  2. Thermal and epithermal neutron fluence rate gradient measurements by PADC detectors in LINAC radiotherapy treatments-field

    Energy Technology Data Exchange (ETDEWEB)

    Barrera, M. T., E-mail: mariate9590@gmail.com; Barros, H.; Pino, F.; Sajo-Bohus, L. [Universidad Simón Bolívar, Nuclear Physics Laboratory, Sartenejas, Caracas (Venezuela, Bolivarian Republic of); Dávila, J. [Física Médica C. A. and Universidad Central de Venezuela, Caracas (Venezuela, Bolivarian Republic of)

    2015-07-23

    LINAC VARIAN 2100 is where energetic electrons produce Bremsstrahlung radiation, with energies above the nucleon binding energy (E≈5.5MeV). This radiation induce (γ,n) and (e,e’n) reactions mainly in the natural tungsten target material (its total photoneutron cross section is about 4000 mb in a energy range from 9-17 MeV). These reactions may occur also in other components of the system (e.g. multi leaf collimator). During radiation treatment the human body may receive an additional dose inside and outside the treated volume produced by the mentioned nuclear reactions. We measured the neutron density at the treatment table using nuclear track detectors (PADC-NTD). These covered by a boron-converter are employed, including a cadmium filter, to determine the ratio between two groups of neutron energy, i.e. thermal and epithermal. The PADC-NTD detectors were exposed to the radiation field at the iso-center during regular operation of the accelerator. Neutron are determined indirectly by the converting reaction {sup 10}B(n,α){sup 7}Li the emerging charged particle leave their kinetic energy in the PADC forming a latent nuclear track, enlarged by chemical etching (6N, NaOH, 70°C). Track density provides information on the neutron density through calibration coefficient (∼1.6 10{sup 4} neutrons /track) obtained by a californium source. We report the estimation of the thermal and epithermal neutron field and its gradient for photoneutrons produced in radiotherapy treatments with 18 MV linear accelerators. It was obsered that photoneutron production have higher rate at the iso-center.

  3. Ground state energy of dilute neutron matter at next-to-leading order in lattice chiral effective field theory

    CERN Document Server

    Epelbaum, Evgeny; Lee, Dean; Meißner, Ulf-G

    2008-01-01

    We present lattice calculations for the ground state energy of dilute neutron matter at next-to-leading order in chiral effective field theory. This study follows a series of recent papers on low-energy nuclear physics using chiral effective field theory on the lattice. In this work we introduce an improved spin- and isospin-projected leading-order action which allows for a perturbative treatment of corrections at next-to-leading order and smaller estimated errors. Using auxiliary fields and Euclidean-time projection Monte Carlo, we compute the ground state of 8, 12, and 16 neutrons in a periodic cube, covering a density range from 2% to 10% of normal nuclear density.

  4. Efficient magnetic-field amplification due to the Kelvin-Helmholtz instability in binary neutron star mergers

    CERN Document Server

    Kiuchi, Kenta; Kyutoku, Koutarou; Sekiguchi, Yuichiro; Shibata, Masaru

    2015-01-01

    We explore magnetic-field amplification due to the Kelvin-Helmholtz instability during binary neutron star mergers. By performing high-resolution general relativistic magnetohydrodynamics simulations with a resolution of $17.5$ m for $4$--$5$ ms after the onset of the merger on the Japanese supercomputer "K", we find that an initial magnetic field of moderate maximum strength $10^{13}$ G is amplified at least by a factor of $\\approx 10^3$. We also explore the saturation of the magnetic-field energy and our result shows that it is likely to be $\\gtrsim 4 \\times 10^{50}$ erg, which is $\\gtrsim 0.1\\%$ of the bulk kinetic energy of the merging binary neutron stars.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-07-01

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

  6. Neutron Damage in Mechanically-Cooled High-Purity Germanium Detectors for Field-Portable Prompt Gamma Neutron Activation Analysis (PGNAA) Systems

    Energy Technology Data Exchange (ETDEWEB)

    E.H. Seabury; C.J. Wharton; A.J. Caffrey; J.B. McCabe; C. DeW. Van Siclen

    2013-10-01

    Prompt Gamma Neutron Activation (PGNAA) systems require the use of a gamma-ray spectrometer to record the gamma-ray spectrum of an object under test and allow the determination of the object’s composition. Field-portable systems, such as Idaho National Laboratory’s PINS system, have used standard liquid-nitrogen-cooled high-purity germanium (HPGe) detectors to perform this function. These detectors have performed very well in the past, but the requirement of liquid-nitrogen cooling limits their use to areas where liquid nitrogen is readily available or produced on-site. Also, having a relatively large volume of liquid nitrogen close to the detector can impact some assessments, possibly leading to a false detection of explosives or other nitrogen-containing chemical. Use of a mechanically-cooled HPGe detector is therefore very attractive for PGNAA applications where nitrogen detection is critical or where liquid-nitrogen logistics are problematic. Mechanically-cooled HPGe detectors constructed from p-type germanium, such as Ortec’s trans-SPEC, have been commercially available for several years. In order to assess whether these detectors would be suitable for use in a fielded PGNAA system, Idaho National Laboratory (INL) has been performing a number of tests of the resistance of mechanically-cooled HPGe detectors to neutron damage. These detectors have been standard commercially-available p-type HPGe detectors as well as prototype n-type HPGe detectors. These tests compare the performance of these different detector types as a function of crystal temperature and incident neutron fluence on the crystal.

  7. Axial Symmetric Solutions to Einstein's Field Equations for Deformed Neutron Stars

    Science.gov (United States)

    Zubairi, Omair; Weber, Fridolin

    2016-03-01

    Traditional models of neutron stars are constructed under of assumption that they are perfect spheres. This is not correct, however, if the matter inside of neutron stars is described by an non-isotropic model for the equation of state. Examples of such stars are magnetars and neutron stars that would contain color-superconducting quark matter. In this work, we derive the stellar structure equations which describe the properties of non-isotropic neutron stars. The equations are solved numerically in two dimensions. We calculate stellar properties such as masses and radii along with pressure and density profiles and investigate any changes from conventional spherically symmetric neutron stars. This work was supported through the National Science Foundation under Grants PHYS-1411708 and DUE-1259951. Additional computing resources were provided by the CSRC at SDSU and the Department of Sciences at Wentworth Institute of Technology.

  8. Characterization of extended range Bonner Sphere Spectrometers in the CERF high-energy broad neutron field at CERN

    International Nuclear Information System (INIS)

    The accurate determination of the ambient dose equivalent in the mixed neutron–photon fields encountered around high-energy particle accelerators still represents a challenging task. The main complexity arises from the extreme variability of the neutron energy, which spans over 10 orders of magnitude or more. Operational survey instruments, which response function attempts to mimic the fluence-to-ambient dose equivalent conversion coefficient up to GeV neutrons, are available on the market, but their response is not fully reliable over the entire energy range. Extended range rem counters (ERRC) do not require the exact knowledge of the energy distribution of the neutron field and the calibration can be done with a source spectrum. If the actual neutron field has an energy distribution different from the calibration spectrum, the measurement is affected by an added uncertainty related to the partial overlap of the fluence-to-ambient dose equivalent conversion curve and the response function. For this reason their operational use should always be preceded by an “in-field” calibration, i.e. a calibration made against a reference instrument exposed in the same field where the survey-meter will be employed. In practice the extended-range Bonner Sphere Spectrometer (ERBSS) is the only device which can serve as reference instrument in these fields, because of its wide energy range and the possibility to assess the neutron fluence and the ambient dose equivalent (H⁎(10)) values with the appropriate accuracy. Nevertheless, the experience gained by a number of experimental groups suggests that mandatory conditions for obtaining accurate results in workplaces are: (1) the use of a well-established response matrix, thus implying validation campaigns in reference monochromatic neutrons fields, (2) the expert and critical use of suitable unfolding codes, and (3) the performance test of the whole system (experimental set-up, elaboration and unfolding procedures) in a well

  9. An investigation of methods for neutron dose measurement in high temperature irradiation fields

    Energy Technology Data Exchange (ETDEWEB)

    Kosako, Toshisou; Sugiura, Nobuyuki [Tokyo Univ. (Japan); Kudo, Kazuhiko [Kyushu Univ., Fukuoka (Japan)] [and others

    2000-10-01

    The Japan Atomic Energy Research Institute (JAERI) has been conducting the innovative basic research on high temperature since 1994, which is a series of high temperature irradiation studies using the High Temperature Engineering Test Reactor (HTTR). 'The Task Group for Evaluation of Irradiation Dose under High Temperature Radiation' was founded in the HTTR Utilization Research Committee, which is the promoting body of the innovative basic research. The present report is a summary of investigation which has been made by the Task Group on the present status and subjects of research and development of neutron detectors in high temperature irradiation fields, in view of contributing to high temperature irradiation research using the HTTR. Detectors investigated here in the domestic survey are the following five kinds of in-core detectors: 1) small fission counter, 2) small fission chamber, 3) self-powered detector, 4) activation detector, and 5) optical fiber. In addition, the research and development status in Russia has been investigated. The present report will also be useful as nuclear instrumentation of high temperature gas-cooled reactors. (author)

  10. An investigation of methods for neutron dose measurement in high temperature irradiation fields

    International Nuclear Information System (INIS)

    The Japan Atomic Energy Research Institute (JAERI) has been conducting the innovative basic research on high temperature since 1994, which is a series of high temperature irradiation studies using the High Temperature Engineering Test Reactor (HTTR). 'The Task Group for Evaluation of Irradiation Dose under High Temperature Radiation' was founded in the HTTR Utilization Research Committee, which is the promoting body of the innovative basic research. The present report is a summary of investigation which has been made by the Task Group on the present status and subjects of research and development of neutron detectors in high temperature irradiation fields, in view of contributing to high temperature irradiation research using the HTTR. Detectors investigated here in the domestic survey are the following five kinds of in-core detectors: 1) small fission counter, 2) small fission chamber, 3) self-powered detector, 4) activation detector, and 5) optical fiber. In addition, the research and development status in Russia has been investigated. The present report will also be useful as nuclear instrumentation of high temperature gas-cooled reactors. (author)

  11. Decay heat measurement of fusion related materials in an ITER-like neutron field

    Science.gov (United States)

    Morimoto, Y.; Ochiai, K.; Maekawa, F.; Wada, M.; Nishitani, T.; Takeuchi, H.

    2002-12-01

    Decay heat is one of the most important factors for the safety aspect of ITER. Especially, the prediction of decay heat with an uncertainty less than 15% for the three most important materials, i.e., copper, type-316 stainless steel (SS316) and tungsten, is strongly requested by designers of ITER. To provide experimental decay heat data needed for validation of decay heat calculations for SS316 and copper, an experiment was conducted as the ITER/EDA task T-426. An ITER-like neutron field was constructed, and decay heat source distributions in thick copper and SS316 plates were measured with the whole energy absorption spectrometer. The measured decay heat distributions in the thick sample plates were compared with the predicted values by MCNP calculations. It was found that the use of an effective activation cross-section calculated by MCNP was needed to consider the self-shielding effects and, for both cases, MCNP calculations could predict the decay heat adequately.

  12. Limits on the monopole magnetic field from measurements of the electric dipole moments of atoms, molecules and the neutron

    OpenAIRE

    Flambaum, V. V.; Murray, D. W.

    1996-01-01

    A radial magnetic field can induce a time invariance violating electric dipole moment (EDM) in quantum systems. The EDMs of the Tl, Cs, Xe and Hg atoms and the neutron that are produced by such a field are estimated. The contributions of such a field to the constants, $\\chi$ of the T,P-odd interactions $\\chi_e {\\bf N} \\cdot {\\bf s}/s$ and $\\chi_N {\\bf N} \\cdot {\\bf I}/I$ are also estimated for the TlF, HgF and YbF molecules (where ${\\bf s}$ (${\\bf I}$) is the electron (nuclear) spin and ${\\bf...

  13. Summary report of technical meeting on neutron cross section covariances

    International Nuclear Information System (INIS)

    A summary is given of the Technical Meeting on Neutron Cross Section Covariances. The meeting goal was to assess covariance data needs and recommend appropriate methodologies to address those needs. Discussions on covariance data focused on three general topics: 1) Resonance and unresolved resonance regions; 2) Fast neutron region; and 3) Users' perspective: benchmarks' uncertainty and reactor dosimetry. A number of recommendations for further work were generated and the important work that remains to be done in the field of covariances was identified. (author)

  14. Introducing Nuclear Data Evaluations of Prompt Fission Neutron Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Neudecker, Denise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-06-17

    Nuclear data evaluations provide recommended data sets for nuclear data applications such as reactor physics, stockpile stewardship or nuclear medicine. The evaluated data are often based on information from multiple experimental data sets and nuclear theory using statistical methods. Therefore, they are collaborative efforts of evaluators, theoreticians, experimentalists, benchmark experts, statisticians and application area scientists. In this talk, an introductions is given to the field of nuclear data evaluation at the specific example of a recent evaluation of the outgoing neutron energy spectrum emitted promptly after fission from 239Pu and induced by neutrons from thermal to 30 MeV.

  15. The MCNP6 Analytic Criticality Benchmark Suite

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Forrest B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Monte Carlo Codes Group

    2016-06-16

    Analytical benchmarks provide an invaluable tool for verifying computer codes used to simulate neutron transport. Several collections of analytical benchmark problems [1-4] are used routinely in the verification of production Monte Carlo codes such as MCNP® [5,6]. Verification of a computer code is a necessary prerequisite to the more complex validation process. The verification process confirms that a code performs its intended functions correctly. The validation process involves determining the absolute accuracy of code results vs. nature. In typical validations, results are computed for a set of benchmark experiments using a particular methodology (code, cross-section data with uncertainties, and modeling) and compared to the measured results from the set of benchmark experiments. The validation process determines bias, bias uncertainty, and possibly additional margins. Verification is generally performed by the code developers, while validation is generally performed by code users for a particular application space. The VERIFICATION_KEFF suite of criticality problems [1,2] was originally a set of 75 criticality problems found in the literature for which exact analytical solutions are available. Even though the spatial and energy detail is necessarily limited in analytical benchmarks, typically to a few regions or energy groups, the exact solutions obtained can be used to verify that the basic algorithms, mathematics, and methods used in complex production codes perform correctly. The present work has focused on revisiting this benchmark suite. A thorough review of the problems resulted in discarding some of them as not suitable for MCNP benchmarking. For the remaining problems, many of them were reformulated to permit execution in either multigroup mode or in the normal continuous-energy mode for MCNP. Execution of the benchmarks in continuous-energy mode provides a significant advance to MCNP verification methods.

  16. Standard neutron fields in graphite prism with Ra-α-Be source

    International Nuclear Information System (INIS)

    Neutron slowing-down and space-energy distribution of neutron flux in graphite prism with Ra-α-Be source were investigated experimentally, numerically and theoretically. Recent measurement and numerical experiment based on Monte Carlo calculations were carried out for the purpose of determining detailed space and energy distribution of neutron flux in the prism. Measurement of two-group neutron flux distribution along the central vertical axis of graphite prism was performed by irradiation of golden foils with cadmium covers and without them. Gamma and beta activities of foils were measured absolutely by using coaxial semiconductor germanium gamma detector and dual gas proportional alpha/beta detector, respectively. Starting from the results of numerical Monte Carlo experiment, neutron ages that enable analytical representation of neutron flux in broad energy intervals were determined. For the six chosen broad energy intervals the very good agreement between numerical experiment and Fermi age theory results was achieved with three age groups, corresponded source fractions and neutron ages. (author)

  17. The Conic Benchmark Format

    DEFF Research Database (Denmark)

    Friberg, Henrik A.

    This document constitutes the technical reference manual of the Conic Benchmark Format with le extension: .cbf or .CBF. It unies linear, second-order cone (also known as conic quadratic) and semidenite optimization with mixed-integer variables. The format has been designed with benchmark libraries...... in mind, and therefore focuses on compact and easily parsable representations. The problem structure is separated from the problem data, and the format moreover facilitate benchmarking of hotstart capability through sequences of changes....

  18. Electric field effects on alignment of lamellar structures in diblock copolymer thin films studied by neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xiuli

    2006-12-07

    We investigated the lamellar orientation in thin films of a diblock copolymer P(S-b-MMA), under competing effects of surface interactions and an electric field applied perpendicular to the substrate. The surface effects tend to align the lamellae parallel to the substrate while the electric field tends to align the lamellae perpendicular to the substrate. Using neutron reflectivity, neutron diffuse scattering, and neutron small-angle scattering, we achieved a quantitative analysis of the internal structure of the films. Film thickness was found to play a non-trivial role in determining the structure of the films. A complete alignment by the surface effects was observed in the thinner films by annealing. The parallel orientation remains stable even if an electric field as strong as 40 V/{mu}m is applied. In the thicker films, a mixed orientation with boundary layers parallel and the central part partially perpendicular to the substrate was observed after annealing. The mixed orientation becomes unstable under a small compressive stress, and will be converted into a completely parallel orientation. The parallel orientation induced by the compressive stress remains stable as long as the electric field is weaker than several ten V/{mu}m. Only a field of about 40 V/{mu}m is able to stabilize the above mentioned mixed orientation. A fully perpendicular orientation was never observed in our experiments. Diffuse scattering shows a mosaic structure in the absence of an electric field, whose mosaicity will be increased by the torque exerted by an electric field. The lateral correlation length of the lamellar domains is estimated as 1-2 {mu}m. Limited by the small q{sub x}-range we have used, a clear statement on the existence of the electric-field-induced structural undulations predicted by the Onuki's theory cannot be made from our experiments. (orig.)

  19. The investigation of correspondence of indications of the albedo dosemeter DVGN-01 to personnel irradiation doses in the fields of neutron radiation at the JINR nuclear power installations

    International Nuclear Information System (INIS)

    The calculated results of the research correspondence of the indication of the individual albedo dosemeter DVGN-01 to the individual equivalent dose for neutrons Hp(10) and to the effective dose for neutrons Eeff in the neutron fields at the JINR Nuclear Power Installations (JNPI) at different geometries of irradiations are presented. It has been shown that the correction coefficients are required for specific estimation of doses by the dosemeter. The coefficients were calculated using the energy sensitivity curve of the dosemeter and the known neutron spectra at the JNPI. By using the correction factors the uncertainties of both doses would not exceed the limits given to the personnel according to standards

  20. Aeroelastic Benchmark Experiments Project

    Data.gov (United States)

    National Aeronautics and Space Administration — M4 Engineering proposes to conduct canonical aeroelastic benchmark experiments. These experiments will augment existing sources for aeroelastic data in the...

  1. Dosimetry of an accident in mixed field (neutrons, photons) using the spectrometry by electronic paramagnetic resonance(EPR)

    International Nuclear Information System (INIS)

    In a radiological accident, the assessment of the dose received by the victim is relevant information for the therapeutic strategy. Two complementary dosimetric techniques based on physical means are used in routine practice in the laboratory: EPR spectroscopy performed on materials removed from the victim or gathered from the vicinity of the victim and Monte Carlo calculations. EPR dosimetry, has been used successfully several times in cases of photon or electron overexposures. Accidental exposure may also occur with a neutron component. The aim of this work is to investigate the potentiality of EPR dosimetry for mixed photon and neutron field exposure with different organic materials (ascorbic acid, sorbitol, glucose, galactose, fructose, mannose, lactose and sucrose). The influence of irradiation parameters (dose, dose rate, photon energy) and of environmental parameters (temperature of heating, light exposure) on the EPR signal amplitude was studied. To assess the neutron sensitivity, the materials were exposed to a mixed radiation field of experimental reactors with different neutron to photon ratios. The relative neutron sensitivity was found to range from 10% to 43% according to the materials. Prior knowledge of the ratio between the dose in samples measured by EPR spectrometry and organ or whole body dose obtained by calculations previously performed for these different configurations, makes it possible to give a first estimation of the dose received by the victim in a short delay. The second aim of this work is to provide data relevant for a quick assessment of the dose distribution in case of accidental overexposure based on EPR measurements performed on one or several points of the body. The study consists in determining by calculation the relation between the dose to the organs and whole body and the dose to specific points of the body, like teeth, bones or samples located in the pockets of victim clothes, for different external exposures corresponding

  2. Study of Neutron Magic Drip-Line Nuclei within Relativistic Mean Field plus BCS Approach

    OpenAIRE

    Saxena, G.; Singh, D.; Kaushik, M.; Yadav, H. L.; Toki, H.

    2013-01-01

    Encouraged by the success of RMF+BCS approach for the description of the ground state properties of the chains of isotopes of proton magic nuclei with proton number Z=8, 20, 28, 50 and 82 as well as those of proton sub-magic nuclei with Z=40, we have further employed it, in an analogous manner, for a detailed calculations of the ground state properties of the neutron magic isotones with neutron number N = 8, 20, 28, 50, 82 and 126 as well as those of neutron sub-magic isotones with N = 40 usi...

  3. Confinement of ultra-cold neutron in a multiple cusp magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Akiyama, Nobumichi; Inoue, Nobuyuki; Nihei, Hitoshi; Kinosita, Ken-ichi [Tokyo Univ. (Japan). Faculty of Engineering

    1996-08-01

    A new confinement system of ultra-cold neutrons is proposed. The neutron bottle is made of a rectangular vacuum chamber with the size of 40 cm x 40 cm x 30 cm covered with arrays of bar type permanent magnets. The operation of bottle requires neither cooling system nor high electric power supply, and thereby the bottle is appropriate to use in the room which is located in controlled area. The maximum kinetic energy of neutrons confined is 20 neV. Experimental scheme to test the performance of the bottle is described. (author)

  4. Validation of the neutron and gamma fields in the JSI TRIGA reactor using in-core fission and ionization chambers.

    Science.gov (United States)

    Žerovnik, Gašper; Kaiba, Tanja; Radulović, Vladimir; Jazbec, Anže; Rupnik, Sebastjan; Barbot, Loïc; Fourmentel, Damien; Snoj, Luka

    2015-02-01

    CEA developed fission chambers and ionization chambers were utilized at the JSI TRIGA reactor to measure neutron and gamma fields. The measured axial fission rate distributions in the reactor core are generally in good agreement with the calculated values using the Monte Carlo model of the reactor thus verifying both the computational model and the fission chambers. In future, multiple absolutely calibrated fission chambers could be used for more accurate online reactor thermal power monitoring. PMID:25479432

  5. Simultaneous soil moisture and properties estimation for a drip irrigated field by assimilating cosmic-ray neutron intensity

    Science.gov (United States)

    Han, Xujun; Hendricks Franssen, Harrie-Jan; Jiménez Bello, Miguel Ángel; Rosolem, Rafael; Bogena, Heye; Alzamora, Fernando Martínez; Chanzy, André; Vereecken, Harry

    2016-08-01

    Neutron intensity measured by the aboveground cosmic-ray neutron intensity probe (CRP) allows estimating soil moisture content at the field scale. In this work, synthetic neutron intensities were used to remove the bias of simulated soil moisture content or update soil hydraulic properties (together with soil moisture) in the Community Land Model (CLM) using the Local Ensemble Transform Kalman Filter. The cosmic-ray forward model COSMIC was used as the non-linear measurement operator which maps between neutron intensity and soil moisture. The novel aspect of this work is that synthetically measured neutron intensity was used for real time updating of soil states and soil properties (or soil moisture bias) and posterior use for the real time scheduling of irrigation (data assimilation based real-time control approach). Uncertainty of model forcing and soil properties (sand fraction, clay fraction and organic matter density) were considered in the ensemble predictions of the soil moisture profiles. Horizontal and vertical weighting of soil moisture was introduced in the data assimilation in order to handle the scale mismatch between the cosmic-ray footprint and the CLM grid cell. The approach was illustrated in a synthetic study with the real-time irrigation scheduling of fields of citrus trees. After adjusting soil moisture content by assimilating neutron intensity, the irrigation requirements were calculated based on the water deficit method. Model bias was introduced by using coarser soil texture in the data assimilation experiments than in reality. A series of experiments was done with different combinations of state, parameter and bias estimation in combination with irrigation scheduling. Assimilation of CRP neutron intensity improved soil moisture characterization. Irrigation requirement was overestimated if biased soil properties were used. The soil moisture bias was reduced by 35% after data assimilation. The scenario of joint state-parameter estimation

  6. Development of a neutron converter for studies of neutron-induced fission fragments at the IGISOL facility

    CERN Document Server

    Lantz, M; Al-Adili, A; Jokinen, A; Kolhinen, V; Mattera, A; Rinta-Antila, S; Penttilä, H; Pomp, S; Rakoupoulos, V; Simutkin, V; Solders, A

    2014-01-01

    The ERINDA funded scientific visit has enabled the groups at U ppsala Uni- versity and University of Jyväskylä to work closer together on the design of a neutron converter that will be used as neutron source in fissi on yield studies at the IGISOL-JYFLTRAP facility at the University of Jyväsk ylä. The design is based on simulations with both deterministic codes and Mo nte Carlo codes, and an ERINDA funded benchmark measurement. In order to obta in a com- petitive count rate the fission targets will be placed very cl ose to the neutron converter. The intention is to have a flexible design that wil l enable neutron fields with different energy distributions. In this report t he progression and the present status of the design work will be discussed, togethe r with an outlook of the future plans

  7. The Ocean and Crust of a Rapidly Accreting Neutron Star Implications for Magnetic Field Evolution and Thermonuclear Flashes

    CERN Document Server

    Brown, E F; Brown, Edward F.; Bildsten, Lars

    1998-01-01

    We investigate the atmosphere, ocean, and crust of neutron stars accreting at rates sufficiently high (typically in excess of the local Eddington limit) to stabilize the burning of accreted hydrogen and helium. For hydrogen-rich accretion at global rates in excess of 10^-8 solar masses per year (typical of a few neutron stars), we discuss the thermal state of the deep ocean and crust and their coupling to the neutron star core, which is heated by conduction (from the crust) and cooled by neutrino emission. We estimate the Ohmic diffusion time in the hot, deep crust and find that it is noticeably shortened (to less than 10^8 yr) from the values characteristic of the colder crusts in slowly accreting neutron stars. We speculate on the implications of these calculations for magnetic field evolution in the bright accreting X-ray sources. We also explore the consequences of rapid compression at local accretion rates exceeding ten times the Eddington rate. This rapid accretion heats the atmosphere/ocean to temperat...

  8. Benchmark calculations of sodium fast critical experiments

    International Nuclear Information System (INIS)

    The high expectations from fast critical experiments impose the additional requirements on reliability of final reconstructed values, obtained in experiments at critical facility. Benchmark calculations of critical experiments are characterized by impossibility of complete experiment reconstruction, the large amounts of input data (dependent and independent) with very different reliability. It should also take into account different sensitivity of the measured and appropriate calculated characteristics to the identical changes of geometry parameters, temperature, and isotopic composition of individual materials. The calculations of critical facility experiments are produced for the benchmark models, generated by the specific reconstructing codes with its features when adjusting model parameters, and using the nuclear data library. The generated benchmark model, providing the agreed calculated and experimental values for one or more neutronic characteristics can lead to considerable differences for other key characteristics. The sensitivity of key neutronic characteristics to the extra steel allocation in the core, and ENDF/B nuclear data sources is performed using a few calculated models of BFS-62-3A and BFS1-97 critical assemblies. The comparative analysis of the calculated effective multiplication factor, spectral indices, sodium void reactivity, and radial fission-rate distributions leads to quite different models, providing the best agreement the calculated and experimental neutronic characteristics. This fact should be considered during the refinement of computational models and code-verification purpose. (author)

  9. Time-dependent thermal neutron field in two-region bounded systems

    International Nuclear Information System (INIS)

    A set of solutions of the time-dependent diffusion equation for two-region bounded systems in spherical and cylindrical geometries is presented. Two types of solutions are given for each geometry: the general solution and a solution for the case where the spatial distribution of the thermal neutron flux is constant inside the inner region. These solutions provide the theoretical background for the development of a new method of measuring the thermal neutron macroscopic absorption cross section. The theoretical description of the method worked out for small samples is in good agreement with the experimental results presented. The principles of measuring the neutron transport cross section using small samples and mathematical solutions are described. The possibility of applying a sinusoidally modulated neutron source is presented. Special attention is paid to proper averaging of the thermal neutron diffusion parameters and to the problem of boundary effects. The so-called thermal neutron average dynamic parameters have been used. Results obtained from the modified diffusion theory compare satisfactorily with those obtained form the one-speed transport and P3 theory approximations. (au) (56 refs.)

  10. Measurements of neutrons at JET by means of the activation methods

    Energy Technology Data Exchange (ETDEWEB)

    Prokopowicz, R., E-mail: prokopowicz@ifpilm.waw.p [EURATOM-IPPLM Association, 23, Hery St, Warsaw 01-497 (Poland); Bienkowska, B.; Drozdowicz, K.; Jednorog, S.; Kowalska-Strzeciwilk, E. [EURATOM-IPPLM Association, 23, Hery St, Warsaw 01-497 (Poland); Murari, A. [EURATOM-ENEA Fusion Association, Consorzio RFX, Padova I-35127 (Italy); Popovichev, S. [EURATOM-CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Pytel, K.; Scholz, M.; Szydlowski, A. [EURATOM-IPPLM Association, 23, Hery St, Warsaw 01-497 (Poland); Syme, B. [EURATOM-CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Tracz, G. [EURATOM-IPPLM Association, 23, Hery St, Warsaw 01-497 (Poland)

    2011-05-01

    The neutron diagnostics in tokamaks like Joint European Torus (JET) are essential in estimating fusion power. The neutron activation method, supported by neutron transport calculations, is particularly useful for the evaluation of the total neutron yield from a single plasma discharge. This paper presents the results of activation experiments and calculations carried out for JET plasmas, from the selection of the activation materials to their irradiations in the neutron field of JET discharges. Neutron transport calculations were performed, leading to activation coefficients for new materials. The results of the calculations were used to design new composite samples to obtain information on both the yield and the neutron spectrum. The neutron measurements using these new activation materials were performed during the last JET experimental campaigns. The results are compared with neutron transport calculations. Additionally, application of the cadmium difference method allows revelation of the part of thermal neutrons near the tokamak first wall. The advantages of new activation materials and benchmarking the activation method against neutron transport calculations are also discussed.

  11. Precision of neutron scattering and capacitance type soil water content gauges from field calibration

    International Nuclear Information System (INIS)

    Soil water content gauges based on neutron scattering (NS) have been a valuable tool for soil water investigations for some 40 yr. However, licensing, training, and safety regulations pertaining to the radioactive source in these gauges makes their use expensive and prevents use in some situations such as unattended monitoring. A capacitance probe (CP) gauge has characteristics that would seem to make it an ideal replacement for NS gauges. We determined the relative precision of two brands of NS gauges (three gauges of each) and a brand of CP gauge (four gauges) in a field calibration exercise. Both brands of NS gauges were calibrated vs. volumetric soil water content with coefficients of determination (r2) ranging from 0.97 to 0.99 and root mean squared errors (RMSE) 0.012 m3 m-3 water content. Calibrations for the CP gauges resulted in r2 ranging from 0.68 to 0.71 and RMSE of 0.036 m3 m-3 water content. Average 95% confidence intervals on predictions were three to five times higher for the CP gauges than for the NS gauges, ranging from 0.153 to 0.161 and 0.032 to 0.052 m3 m-3, respectively. Although poorly correlated with soil water content, readings were reproducible among the four CP gauges. The poor correlation for CP gauges may be due to small-scale soil water content variations within the measurement volume of the gauge. The NS gauges provide acceptable precision but the CP gauge has poor precision and is unacceptable for routine soil water content measurements

  12. PHITS simulations of absorbed dose out-of-field and neutron energy spectra for ELEKTA SL25 medical linear accelerator

    International Nuclear Information System (INIS)

    Monte Carlo (MC) based calculation methods for modeling photon and particle transport, have several potential applications in radiotherapy. An essential requirement for successful radiation therapy is that the discrepancies between dose distributions calculated at the treatment planning stage and those delivered to the patient are minimized. It is also essential to minimize the dose to radiosensitive and critical organs. With MC technique, the dose distributions from both the primary and scattered photons can be calculated. The out-of-field radiation doses are of particular concern when high energy photons are used, since then neutrons are produced both in the accelerator head and inside the patients. Using MC technique, the created photons and particles can be followed and the transport and energy deposition in all the tissues of the patient can be estimated. This is of great importance during pediatric treatments when minimizing the risk for normal healthy tissue, e.g. secondary cancer. The purpose of this work was to evaluate 3D general purpose PHITS MC code efficiency as an alternative approach for photon beam specification. In this study, we developed a model of an ELEKTA SL25 accelerator and used the transport code PHITS for calculating the total absorbed dose and the neutron energy spectra infield and outside the treatment field. This model was validated against measurements performed with bubble detector spectrometers and Boner sphere for 18 MV linacs, including both photons and neutrons. The average absolute difference between the calculated and measured absorbed dose for the out-of-field region was around 11%. Taking into account a simplification for simulated geometry, which does not include any potential scattering materials around, the obtained result is very satisfactorily. A good agreement between the simulated and measured neutron energy spectra was observed while comparing to data found in the literature. (note)

  13. Internet based benchmarking

    DEFF Research Database (Denmark)

    Bogetoft, Peter; Nielsen, Kurt

    2005-01-01

    We discuss the design of interactive, internet based benchmarking using parametric (statistical) as well as nonparametric (DEA) models. The user receives benchmarks and improvement potentials. The user is also given the possibility to search different efficiency frontiers and hereby to explore...

  14. Handleiding benchmark VO

    NARCIS (Netherlands)

    Blank, j.l.t.

    2008-01-01

    OnderzoeksrapportenArchiefTechniek, Bestuur en Management> Over faculteit> Afdelingen> Innovation Systems> IPSE> Onderzoek> Publicaties> Onderzoeksrapporten> Handleiding benchmark VO Handleiding benchmark VO 25 november 2008 door IPSE Studies Door J.L.T. Blank. Handleiding voor het lezen van de i

  15. Benchmark af erhvervsuddannelserne

    DEFF Research Database (Denmark)

    Bogetoft, Peter; Wittrup, Jesper

    I dette arbejdspapir diskuterer vi, hvorledes de danske erhvervsskoler kan benchmarkes, og vi præsenterer resultaterne af en række beregningsmodeller. Det er begrebsmæssigt kompliceret at benchmarke erhvervsskolerne. Skolerne udbyder en lang række forskellige uddannelser. Det gør det vanskeligt...

  16. Enhanced Magnetism in Field-Cooled [Ni80Fe20/Mn]3 Multilayers Studied Using Polarized Neutron Reflectometry

    Science.gov (United States)

    Uilhoorn, W.; Callori, S. J.; Cortie, D. L.; Su, H.-C.; Khaydukov, Y.; Lin, K.-W.; Klose, F.

    2016-04-01

    Here, the interfacial magnetic coupling in an exchange biased [Ni80Fe20/Mn]3 multilayer system has been studied using polarized neutron reflectometry. Previous results on this system indicate the importance of the coupling between the Fe-Mn and Ni-Mn orbitals at the layer interfaces. Magnetic depth profiles of the multilayer were measured at low temperatures under field-cooled and zero-field-cooled conditions. While no definitive interfacial state was found, a magnetic moment enhancement of roughly 20-30% in the applied field direction was observed throughout the bulk of the NiFe layers in the field-cooled state as compared to the zero-field-cooled measurements. The origin of this enhancement also likely stems from Fe-Mn and Ni-Mn orbital coupling, but due to the interfacial roughnesses of the sample, the areas where this coupling plays an important role is no longer confined to the interface.

  17. Quinolone and glycopeptide therapy for infection in mouse following exposure to mixed-field neutron-[gamma]-photon radiation

    Energy Technology Data Exchange (ETDEWEB)

    Brook, I. (Naval Medical Research Inst., Bethesda, MD (United States) Armed Forces Radiobiology Research Inst., Bethesda, MD (United States)); Tom, S.P.; Ledney, G.D. (Armed Forces Radiobiology Research Inst., Bethesda, MD (United States))

    1993-12-01

    The effects of increased doses of mixed-field neutron-[gamma]-photon irradiation on bacterial translocation and subsequent sepsis, and the influence of antimicrobial therapy on these events, were studied in the C3H/HeN mouse. The results demonstrate a relationship between the doses of mixed-field radiation and the rates of infection due to Enterobacteriaceae. While L-ofloxacin therapy reduces the infection rate, prolongs survival and prevents mortality, the addition of a glycopeptide can enhance systemic infection by resistant bacteria in the irradiated host. (author).

  18. Design and commissioning of a high magnetic field muon spin relaxation spectrometer at the ISIS pulsed neutron and muon source

    Energy Technology Data Exchange (ETDEWEB)

    Lord, J. S.; McKenzie, I.; Baker, P. J.; Cottrell, S. P.; Giblin, S. R.; Hillier, A. D.; Holsman, B. H.; King, P. J. C.; Nightingale, J. B.; Pratt, F. L.; Rhodes, N. J. [ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX (United Kingdom); Blundell, S. J.; Lancaster, T. [Clarendon Laboratory, Department of Physics, Oxford University, Parks Road, Oxford OX1 3PU (United Kingdom); Good, J.; Mitchell, R.; Owczarkowski, M.; Poli, S. [Cryogenic Limited, 30 Acton Park Industrial Estate, The Vale, Acton, London W3 7QE (United Kingdom); Scheuermann, R. [Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Salman, Z. [ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX (United Kingdom); Clarendon Laboratory, Department of Physics, Oxford University, Parks Road, Oxford OX1 3PU (United Kingdom)

    2011-07-15

    The high magnetic field (HiFi) muon instrument at the ISIS pulsed neutron and muon source is a state-of-the-art spectrometer designed to provide applied magnetic fields up to 5 T for muon studies of condensed matter and molecular systems. The spectrometer is optimised for time-differential muon spin relaxation studies at a pulsed muon source. We describe the challenges involved in its design and construction, detailing, in particular, the magnet and detector performance. Commissioning experiments have been conducted and the results are presented to demonstrate the scientific capabilities of the new instrument.

  19. Neutron field measurements of the CRNA OB26 irradiator using a Bonner sphere spectrometer for radiation protection purposes.

    Science.gov (United States)

    Mazrou, H; Allab, M

    2012-08-01

    The present work deals with the Bonner sphere spectrometer (BSS) measurements performed, to support the authors' Monte-Carlo calculations, to estimate accurately the main characteristics of the neutron field of the (241)Am-Be-based OB26 irradiator acquired for radiation protection purposes by the Nuclear Research Centre of Algiers. The measurements were performed at a reference irradiation position selected at 150 cm from the geometrical centre of the neutron source. The spectrometric system in use is based on a central spherical (3)He thermal neutron proportional counter. The response matrix of the present spectrometer has been taken to be similar to the original Physikalisch-Technische Bundesanstalt (PTB) (Braunschweig, Germany) BSS's response matrix, with a five bins per decade energy group structure, as there is no significant difference in the BSS's physical characteristics. Thereafter, the authors' BSS measurements were used together with MCNP5 results to unfold the neutron spectrum by means of MAXED and GRAVEL computer codes from the U.M.G. 3.3 package, developed at PTB. Besides, sensitivity analysis has been performed to test the consistency of the unfolding procedure. It reveals that no significant discrepancy was observed in the total neutron fluence and total ambient dose values following the perturbation of some pertinent unfolding parameters except for the case where a 10 bins energy structure was assumed for the guess spectrum. In this latter case, a 5 % difference was observed in the ambient dose equivalent compared with the reference case. Finally, a comparative study performed between different counting systems together with MCNP5 and predictive formulas results shows that they were globally satisfactory, highlighting thereby the relevance of the unfolding procedure and the reliability of the obtained results.

  20. Investigation of electric fields, losses and depolarization of ultra-cold neutrons for the new nEDM experiment at FRM II

    OpenAIRE

    Chesnevskaya, Svetlana

    2015-01-01

    This work has shown that the electric field can be produced using different conductive plastics for a high-voltage electrode. Simulations of the electric field and systematic effects result in false effects one or two orders below the statistical uncertainties. Using glass and aluminum as neutron guides and different wall coatings for them, ultra-cold neutron losses and depolarization can be kept below the critical value to allow a measurement goal of 5·10-28 e·cm.