WorldWideScience

Sample records for energy-independent spherical-type neutron

  1. Spherical neutron generator

    Science.gov (United States)

    Leung, Ka-Ngo

    2006-11-21

    A spherical neutron generator is formed with a small spherical target and a spherical shell RF-driven plasma ion source surrounding the target. A deuterium (or deuterium and tritium) ion plasma is produced by RF excitation in the plasma ion source using an RF antenna. The plasma generation region is a spherical shell between an outer chamber and an inner extraction electrode. A spherical neutron generating target is at the center of the chamber and is biased negatively with respect to the extraction electrode which contains many holes. Ions passing through the holes in the extraction electrode are focused onto the target which produces neutrons by D-D or D-T reactions.

  2. Proposal of a neutron transmutation doping facility for n-type spherical silicon solar cell at high-temperature engineering test reactor.

    Science.gov (United States)

    Ho, Hai Quan; Honda, Yuki; Motoyama, Mizuki; Hamamoto, Shimpei; Ishii, Toshiaki; Ishitsuka, Etsuo

    2018-05-01

    The p-type spherical silicon solar cell is a candidate for future solar energy with low fabrication cost, however, its conversion efficiency is only about 10%. The conversion efficiency of a silicon solar cell can be increased by using n-type silicon semiconductor as a substrate. This study proposed a new method of neutron transmutation doping silicon (NTD-Si) for producing the n-type spherical solar cell, in which the Si-particles are irradiated directly instead of the cylinder Si-ingot as in the conventional NTD-Si. By using a 'screw', an identical resistivity could be achieved for the Si-particles without a complicated procedure as in the NTD with Si-ingot. Also, the reactivity and neutron flux swing could be kept to a minimum because of the continuous irradiation of the Si-particles. A high temperature engineering test reactor (HTTR), which is located in Japan, was used as a reference reactor in this study. Neutronic calculations showed that the HTTR has a capability to produce about 40t/EFPY of 10Ωcm resistivity Si-particles for fabrication of the n-type spherical solar cell. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Development of a spherical neutron rem monitor

    International Nuclear Information System (INIS)

    Panchal, C.G.; Madhavi, V.; Bansode, P.Y.; Jakati, R.K.; Ghodgaonkar, M.D.; Desai, S.S.; Shaikh, A.M.; Sathian, V.

    2007-01-01

    A new neutron rem monitor based on spherical LINUS with the state of art electronic circuits has been designed in Electronics Division. This prototype instrument encompasses a spherical double polythene moderator to improve an isotropic response and a lead layer to extend its energy response compared to the conventional neutron rem monitors. A systematic testing and calibration of the energy and directional response of the prototype monitor have been carried out. Although the monitor is expected to perform satisfactorily upto an energy ∼ 55 MeV, at present its response has been tested upto 5 MeV. (author)

  4. Measurements of 14 MeV neutron multiplication in spherical beryllium shells

    International Nuclear Information System (INIS)

    Moellendorff, U. von; Alevra, A.V.; Giese, H.; Kappler, F.; Klein, H.; Klein, H.; Tayama, R.

    1995-01-01

    New results of spherical-shell transmission measurements with 14MeV neutrons on pure beryllium shells up to 17cm thick are reported. The total leakage neutron multiplications were measured using a Bonner sphere system. Independently, the leakage neutron spectra were measured over the entire energy range, 15MeV to thermal energies, by proton-recoil and time-of-flight methods. The total leakage multiplications are in excellent agreement with three-dimensional Monte Carlo calculations using beryllium nuclear data based on the Young and Stewart evaluation. The leakage in the evaporation energy window confirms the Be(n,2n) cross-section of the Young and Stewart evaluation rather than that used in the ENDF/B-VI library. At energies below 1keV, a surplus of leakage neutrons over the calculation is found for smaller beryllium thicknesses. (orig.)

  5. Neutron production in a spherical phantom aboard ISS

    International Nuclear Information System (INIS)

    Tasbaz, A.; Machrafi, R.

    2012-01-01

    As part of an ongoing research program on radiation monitoring on International Space Station (ISS) that was established to analyze the radiation exposure levels onboard the ISS using different radiation instruments and a spherical phantom to simulate human body. Monte Carlo transport code was used to simulate the interaction of high energy protons and neutrons with the spherical phantom currently onboard ISS. The phantom has been exposed to individual proton energies and to a spectrum of neutrons. The internal to external neutron flux ratio was calculated and compared to the experimental data, recently, measured on the ISS. (author)

  6. The Karlsruhe Neutron Transmission Experiment (KANT): Spherical shell transmission measurements with 14 MeV neutrons on beryllium

    International Nuclear Information System (INIS)

    Moellendorff, U. von; Fischer, U.; Giese, H.; Kappler, F.; Tayama, R.; Wiegner, E.; Klein, H.; Alevra, A.

    1996-01-01

    This is a set of viewgraphs (no additional text) of a presentation on spherical shell transmission measurements with 14 MeV neutrons on beryllium; the cross for 9 Be(n,2n)2α for the energy range between threshold (1.85 MeV) and 20 MeV neutron energy is measured and the measurement is compared with the literature. Also, neutron leakage multiplication in spherical Be shells with various thicknesses are presented. Figs, tabs

  7. Spherical harmonics and energy polynomial solution of the Boltzmann equation for neutrons, 1

    International Nuclear Information System (INIS)

    Toledo, P.S. de

    1974-01-01

    The approximate solution of the source-free energy-dependent Boltzmann transport equation for neutrons in plane geometry and isotropic scattering case was given by Leonard and Ferziger using a truncated development in a series of energy-polynomials for the energy dependent neutron flux and solving exactly for the angular dependence. The presence in the general solution of eigenfunctions belonging to a continuous spectrum gives rise to difficult analytical problems in the application of their method even to simple problems. To avoid such difficulties, the angular dependence is treated by a spherical harmonics method and a general solution of the energy-dependent transport equation in plane geometry and isotropic scattering is obtained, in spite of the appearance of matrices as argument of the angular polynomials [pt

  8. A modular spherical harmonics approach to the neutron transport equation

    International Nuclear Information System (INIS)

    Inanc, F.; Rohach, A.F.

    1989-01-01

    A modular nodal method was developed for solving the neutron transport equation in 2-D xy coordinates. The spherical harmonic expansion was used for approximating the second-order even-parity form of the neutron transport equation. The boundary conditions of the spherical harmonics approximation were derived in a form to have forms analogous to the partial currents in the neutron diffusion equation. Relations were developed for generating both the second-order spherical harmonic equations and the boundary conditions in an automated computational algorithm. Nodes using different orders of the spherical harmonics approximation to the transport equation were interfaced through mixed-type boundary conditions. The determination of spherical harmonic orders implemented in the nodes were determined by the scheme in an automated manner. Results of the method compared favorably to benchmark problems. (author)

  9. Cellular neural network to the spherical harmonics approximation of neutron transport equation in x-y geometry. Part I: Modeling and verification for time-independent solution

    International Nuclear Information System (INIS)

    Pirouzmand, Ahmad; Hadad, Kamal

    2011-01-01

    Highlights: → This paper describes the solution of time-independent neutron transport equation. → Using a novel method based on cellular neural networks (CNNs) coupled with P N method. → Utilize the CNN model to simulate spatial scalar flux distribution in steady state. → The accuracy, stability, and capabilities of CNN model are examined in x-y geometry. - Abstract: This paper describes a novel method based on using cellular neural networks (CNN) coupled with spherical harmonics method (P N ) to solve the time-independent neutron transport equation in x-y geometry. To achieve this, an equivalent electrical circuit based on second-order form of neutron transport equation and relevant boundary conditions is obtained using CNN method. We use the CNN model to simulate spatial response of scalar flux distribution in the steady state condition for different order of spherical harmonics approximations. The accuracy, stability, and capabilities of CNN model are examined in 2D Cartesian geometry for fixed source and criticality problems.

  10. Neutronic study of spherical cold-neutron sources composed of liquid hydrogen and liquid deuterium

    CERN Document Server

    Matsuo, Y; Nagaya, Y

    2003-01-01

    Using the cross-section model for neutron scattering in liquid H sub 2 and D sub 2 , a neutron transport analysis is performed for spherical cold-neutron sources composed of either para H sub 2 , normal H sub 2 or normal D sub 2. A special effort is made to generate a set of energy-averaged cross-sections (80 group constants between 0.1 mu eV and 10 eV) for liquid H sub 2 and D sub 2 at melting and boiling points. A number of conclusions on the spherical cold-neutron source configurations are drawn. It is especially shown that the highest cold-neutron flux is obtainable from the normal D sub 2 source with a radius of about 50 cm, while the normal- and para-H sub 2 sources with radii around 3-4 cm produce maximum cold-neutron fluxes at the center.

  11. A method for solving the spherical harmonics equations applied for space-energy transport of fast and resonance neutrons

    International Nuclear Information System (INIS)

    Matausek, M.

    1972-01-01

    A new proposed method for solving the space-energy dependent spherical harmonics equations represents a methodological contribution to neutron transport theory. The proposed method was applied for solving the problem of spec-energy transport of fast and resonance neutrons in multi-zone, cylindrical y symmetric infinite reactor cell and is related to previously developed procedure for treating the thermal energy region. The advantages of this method are as follows: a unique algorithm was obtained for detailed determination of spatial and energy distribution of neutrons (from thermal to fast) in the reactor cell; these detailed distributions enable more precise calculations of criticality conditions, obtaining adequate multigroup data and better interpretation of experimental data; computing time is rather short

  12. Neutron Generation by Laser-Driven Spherically Convergent Plasma Fusion

    Science.gov (United States)

    Ren, G.; Yan, J.; Liu, J.; Lan, K.; Chen, Y. H.; Huo, W. Y.; Fan, Z.; Zhang, X.; Zheng, J.; Chen, Z.; Jiang, W.; Chen, L.; Tang, Q.; Yuan, Z.; Wang, F.; Jiang, S.; Ding, Y.; Zhang, W.; He, X. T.

    2017-04-01

    We investigate a new laser-driven spherically convergent plasma fusion scheme (SCPF) that can produce thermonuclear neutrons stably and efficiently. In the SCPF scheme, laser beams of nanosecond pulse duration and 1 014- 1 015 W /cm2 intensity uniformly irradiate the fuel layer lined inside a spherical hohlraum. The fuel layer is ablated and heated to expand inwards. Eventually, the hot fuel plasmas converge, collide, merge, and stagnate at the central region, converting most of their kinetic energy to internal energy, forming a thermonuclear fusion fireball. With the assumptions of steady ablation and adiabatic expansion, we theoretically predict the neutron yield Yn to be related to the laser energy EL, the hohlraum radius Rh, and the pulse duration τ through a scaling law of Yn∝(EL/Rh1.2τ0.2 )2.5. We have done experiments at the ShengGuangIII-prototype facility to demonstrate the principle of the SCPF scheme. Some important implications are discussed.

  13. Optimization of spherical ionization chambers for neutron diagnostics in Tokamak plants

    International Nuclear Information System (INIS)

    Hoenen, F.

    1983-05-01

    For the investigation of neutron emission from fusion plasmas Pulse-Ion-Chamber are favored because of their high temporal resolution, the availability of results immedately after the discharge and their insensitivity to hard X-rays. However to measure ion temperatures below 2 keV with the aid of neutron spectroscopy the detectors have to be improved. Difficulties arise from the fact that in Pulse-Ion-Chambers the pulse height is a function of the position in the chamber where the ion pairs are produced (Induction effect). It will be shown that the induction effect is smaller in spherical ionisation chambers than in cylindrical ones. This means an increase in energy resolution so that neutrons from the D(D,n) 3 He reaction can be analysed with an energy resolution of better than 3% in spherical chambers. (orig./HP) [de

  14. A new expression for determination of fluences from a spherical moderator neutron source for the calibration of spherical neutron measuring devices

    International Nuclear Information System (INIS)

    Khoshnoodi, M.; Sohrabi, M.

    1997-01-01

    A new expression modifying the inverse square law for determination of neutron fluences from spherical moderator neutron sources is reported. The formalism is based on the neutron fluence at a point outside the moderator as the summation of fluxes of two groups of neutrons: direct neutrons from the central region of the moderator, and moderated neutrons which, to a first approximation, are scattered from the outermost layers of the spherical moderator. The expression has been further developed for spherical neutron measuring devices with an appropriate geometry factor which corrects the reading of the device for non-uniform irradiation of the detector. The combination of the new fluence function and those of the air and room scattered components introduce a calibration model. The fluence relationship obtained for moderated sources may conveniently be used for calculating the more rapid change of neutron dose at close distances than that which is based on the inverse square dependence. (author)

  15. Equivalent-spherical-shield neutron dose calculations

    International Nuclear Information System (INIS)

    Russell, G.J.; Robinson, H.

    1988-01-01

    Neutron doses through 162-cm-thick spherical shields were calculated to be 1090 and 448 mrem/h for regular and magnetite concrete, respectively. These results bracket the measured data, for reinforced regular concrete, of /approximately/600 mrem/h. The calculated fraction of the high-energy (>20 MeV) dose component also bracketed the experimental data. The measured and calculated doses were for a graphite beam stop bombarded with 100 nA of 800-MeV protons. 6 refs., 2 figs., 1 tab

  16. Novel, spherically-convergent ion systems for neutron source and fusion energy production

    International Nuclear Information System (INIS)

    Barnes, D.C.; Nebel, R.A.; Ribe, F.L.; Schauer, M.M.; Schranck, L.S.; Umstadter, K.R.

    1999-01-01

    Combining spherical convergence with electrostatic or electro-magnetostatic confinement of a nonneutral plasma offers the possibility of high fusion gain in a centimeter-sized system. The physics principles, scaling laws, and experimental embodiments of this approach are presented. Steps to development of this approach from its present proof-of-principle experiments to a useful fusion power reactor are outlined. This development path is much less expensive and simpler, compared to that for conventional magnetic confinement and leads to different and useful products at each stage. Reactor projections show both high mass power density and low to moderate wall loading. This approach is being tested experimentally in PFX-I (Penning Fusion eXperiment-Ions), which is based on the following recent advances: 1) Demonstration, in PFX (our former experiment), that it is possible to combine nonneutral electron plasma confinement with nonthermal, spherical focussing; 2) Theoretical development of the POPS (Periodically Oscillating Plasma Sphere) concept, which allows spherical compression of thermal-equilibrium ions; 3) The concept of a massively-modular approach to fusion power, and associated elimination of the critical problem of extremely high first wall loading. PFX-I is described. PFX-I is being designed as a small (<1.5 cm) spherical system into which moderate-energy electrons (up to 100 kV) are injected. These electrons are magnetically insulated from passing to the sphere and their space charge field is then used to spherically focus ions. Results of initial operation with electrons only are presented. Deuterium operation can produce significant neutron output with unprecedented efficiency (fusion gain Q). copyright 1999 American Institute of Physics

  17. Effects of x-ray and neutron irradiation on spherical colonies

    International Nuclear Information System (INIS)

    Aramaki, Ryoji

    1980-01-01

    Responses of in vitro cultured mammalian cells in spherical colonies to 200 kVp x-rays and D-T neutrons were studied using reproductive capacity as a criterion for survival. Cell lines used were FM3A, L5 and Chinese hamster V79. The spherical colonies exposed to x-rays exhibited two-component survival curves. All cells used were more radio-resistant in spherical colonies than in single cell suspensions. It was suggested that this difference in response was attributable to the presence of hypoxic cells in spherical colonies. Dose-modifying Factor (DMF), the ratios of D 0 of the second slopes of the curves for spherical colonies to those for single cells, were 1.6 for FM3A, 1.8 for L5, and 1.7 for Chinese hamster V79. The hypoxic cell fractions in spherical colonies for FM3A, L5, and Chinese hamster V79, were 0.1, 0.6 and 0.4, respectively, resulting in variations in cell survival in spherical colonies following x-radiation. No significant difference was observed between responses of spherical colonies and single cell suspensions to D-T neutrons. FM3A and Chinese hamster V79 showed two-component survival curves when irradiated with neutrons at 37 0 C, but not at 25 0 C. The repair of potentially lethal and sub-lethal damage was also investigated using FM3A in spherical colonies. No detectable repair of potentially lethal damage was observed for x-rays and D-T neutrons. The effect of neutron fractionation was considerably smaller for spherical colonies as compared to single cells. (author)

  18. Calculation of spherical models of lead with a source of 14 MeV-neutrons

    International Nuclear Information System (INIS)

    Markovskij, D.V.; Borisov, A.A.

    1989-01-01

    Neutron transport calculations for spherical models of lead have been done with the one-dimensional code BLANK realizing the direct Monte Carlo method in the whole range of neutron energies and they are compared with the experimental results. 6 refs, 10 figs, 3 tabs

  19. Testing neutron cross-section files from the BROND-2 and ENDF/B-6 libraries in benchmark experiments on neutron transmission through spherical layers

    International Nuclear Information System (INIS)

    Androsenko, A.A.; Androsenko, P.A.; Blokhin, A.I.; Kulagin, N.T.; Pronyaev, V.G.; Simakov, S.P.

    1997-01-01

    The effect of angular anisotropy in inelastic secondary neutron scattering on neutron leakage spectra from the surface of spherical specimens is investigated. It is shown how inadequate representation of the cross-section structure in the neutron energy resonance region can affect the neutron leakage spectrum. (author). 19 refs, 5 figs, 6 tabs

  20. Testing neutron cross-section files from the BROND-2 and ENDF/B-6 libraries in benchmark experiments on neutron transmission through spherical layers

    Energy Technology Data Exchange (ETDEWEB)

    Androsenko, A A; Androsenko, P A; Blokhin, A I; Kulagin, N T; Pronyaev, V G; Simakov, S P [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

    1997-06-01

    The effect of angular anisotropy in inelastic secondary neutron scattering on neutron leakage spectra from the surface of spherical specimens is investigated. It is shown how inadequate representation of the cross-section structure in the neutron energy resonance region can affect the neutron leakage spectrum. (author). 19 refs, 5 figs, 6 tabs.

  1. An energy and direction independent fast neutron dosemeter based on electrochemically etched CR-39 nuclear track detectors

    International Nuclear Information System (INIS)

    James, K.; Matiullah; Durrani, S.A.

    1987-01-01

    A computer-based model is presented, which simulates the dose equivalent response of electrochemically etched CR-39 to fast neutrons of various energies and angles of incidence. Most previous calculations of the response of CR-39 have neglected the production of recoiling oxygen and carbon nuclei as well as α particles in the CR-39. We calculate that these 'heavy recoils' and α particles are the major source of electrochemically etchable tracks in bare CR-39 at neutron energies above approx. 2 MeV under typical etching conditions. Our calculations have been extended to predict the response of CR-39 used in conjunction with various combinations of polymeric front radiators and we have determined the radiator stack configuration with produces the most energy independent response. Again, the heavy recoils and α particles cannot be neglected and, for energies above approx. 2 MeV, these produce typically about 20% of the total response of our optimum stack. This type of fast neutron dosemeter is, however, strongly direction dependent. We have integrated the response over all appropriate angles to predict the dose equivalent response for two representative neutron fields, and we suggest a method for minimising the angular dependence. (author)

  2. Neutron time-of-flight signals from expanding or contracting spherical sources

    International Nuclear Information System (INIS)

    Murphy, T.J.; Chrien, R.E.; Klare, K.A.

    1996-01-01

    The width of the energy distribution of fusion-produced neutrons is often used as an indication of the temperature of the reacting ions. The Doppler broadening of the neutron energy is due to the center-of-mass velocity of reacting ion pairs and is characterized by the ion temperature for a Maxwellian distribution of ions with zero collective velocity. If there is bulk fluid motion or turbulence characterized by a velocity on the order of the ion thermal speed, a significant additional broadening may introduced. Suggestions of this phenomenon have been observed for two classes of laser targets. The first is a ''gas bag'' target, in which a deuterated hydrocarbon gas is contained in a thin spherical membrane and illuminated uniformly. The second target is an ICF capsule with a deuterated plastic inner layer. In both cases, measured neutron energy distributions were wider than expected from theoretical ion temperatures alone would predict, and if interpreted as indicative of the ion temperature, are inconsistent with the neutron yields observed

  3. Exact analytical solution of time-independent neutron transport equation, and its applications to systems with a point source

    International Nuclear Information System (INIS)

    Mikata, Y.

    2014-01-01

    Highlights: • An exact solution for the one-speed neutron transport equation is obtained. • This solution as well as its derivation are believed to be new. • Neutron flux for a purely absorbing material with a point neutron source off the origin is obtained. • Spherically as well as cylindrically piecewise constant cross sections are studied. • Neutron flux expressions for a point neutron source off the origin are believed to be new. - Abstract: An exact analytical solution of the time-independent monoenergetic neutron transport equation is obtained in this paper. The solution is applied to systems with a point source. Systematic analysis of the solution of the time-independent neutron transport equation, and its applications represent the primary goal of this paper. To the best of the author’s knowledge, certain key results on the scalar neutron flux as well as their derivations are new. As an application of these results, a scalar neutron flux for a purely absorbing medium with a spherically piecewise constant cross section and an isotropic point neutron source off the origin as well as that for a cylindrically piecewise constant cross section with a point neutron source off the origin are obtained. Both of these results are believed to be new

  4. High energy neutron dosimeter

    International Nuclear Information System (INIS)

    Rai, K.S.F.

    1994-01-01

    A device for measuring dose equivalents in neutron radiation fields is described. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning. 2 figures

  5. Exact solution of the neutron transport equation in spherical geometry

    Energy Technology Data Exchange (ETDEWEB)

    Anli, Fikret; Akkurt, Abdullah; Yildirim, Hueseyin; Ates, Kemal [Kahramanmaras Suetcue Imam Univ. (Turkey). Faculty of Sciences and Letters

    2017-03-15

    Solution of the neutron transport equation in one dimensional slab geometry construct a basis for the solution of neutron transport equation in a curvilinear geometry. Therefore, in this work, we attempt to derive an exact analytical benchmark solution for both neutron transport equations in slab and spherical medium by using P{sub N} approximation which is widely used in neutron transport theory.

  6. Symmetry energy and surface properties of neutron-rich exotic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Gaidarov, M. K.; Antonov, A. N. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia 1784 (Bulgaria); Sarriguren, P. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 123, E-28006 Madrid (Spain); Moya de Guerra, E. [Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

    2014-07-23

    The symmetry energy, the neutron pressure and the asymmetric compressibility of spherical Ni, Sn, and Pb and deformed Kr and Sm neutron-rich even-even nuclei are calculated within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy-density functional. The correlation between the thickness of the neutron skin and the characteristics related with the density dependence of the nuclear symmetry energy is investigated for isotopic chains of these nuclei in the framework of the deformed self-consistent mean-field Skyrme HF+BCS method. The mass dependence of the nuclear symmetry energy and the neutron skin thickness are also studied together with the role of the neutron-proton asymmetry. The studied correlations reveal a smoother behavior in the case of spherical nuclei than for deformed ones. We also notice that the neutron skin thickness obtained for {sup 208}Pb with SLy4 force is found to be in a good agreement with the recent data. In addition to the interest that this study may have by itself, we give some numerical arguments in proof of the existence of peculiarities of the studied quantities in Ni and Sn isotopic chains that are not present in the Pb chain.

  7. On the spherical harmonic expansion of the neutron angular distribution function

    Energy Technology Data Exchange (ETDEWEB)

    Depken, Sven

    1959-03-15

    The neutron (one-velocity) angular distribution function is expanded in terms of spherical harmonic tensors. The solution to the equations of the moments is given explicitly and the result is applied to the plane, spherical and cylinder symmetrical cases.

  8. On the spherical harmonic expansion of the neutron angular distribution function

    International Nuclear Information System (INIS)

    Depken, Sven

    1959-03-01

    The neutron (one-velocity) angular distribution function is expanded in terms of spherical harmonic tensors. The solution to the equations of the moments is given explicitly and the result is applied to the plane, spherical and cylinder symmetrical cases

  9. Neutron leakage from Pb and Bc spherical shells with 14 MeV central neutron source

    International Nuclear Information System (INIS)

    Antonov, S.; Daskalov, G.; Ilieva, K.; Jordanova, J.; Prodanova, R.; Zagryadskij, V.A.; Novikov, V.M.; Chuvilin, D.Yu.

    1988-01-01

    Results of measuring neutron leakage from spherical shells of different thickness, made of Pb and Be with a point neutron source in the sphere centrum are presented. The experiment results are compared to calculations according to different programs using data of various nuclear data libraies. The comparison has shown that all the calculations understate the neutron leakage from Pb assmebly. 9 refs.; 2 tabs

  10. Low energy recoil detection with a spherical proportional counter

    Science.gov (United States)

    Savvidis, I.; Katsioulas, I.; Eleftheriadis, C.; Giomataris, I.; Papaevangellou, T.

    2018-01-01

    We present results for the detection of low energy nuclear recoils in the keV energy region, from measurements performed with the Spherical Proportional Counter (SPC). An 241Am-9Be fast neutron source is used in order to obtain neutron-nucleus elastic scattering events inside the gaseous volume of the detector. The detector performance in the keV energy region was measured by observing the 5.9 keV line of a 55Fe X-ray source, with energy resolution of 10% (σ). The toolkit GEANT4 was used to simulate the irradiation of the detector by an 241Am-9Be source, while SRIM was used to calculate the Ionization Quenching Factor (IQF), the simulation results are compared with the measurements. The potential of the SPC in low energy recoil detection makes the detector a good candidate for a wide range of applications, including Supernova or reactor neutrino detection and Dark Matter (WIMP) searches (via coherent elastic scattering).

  11. Computed neutron response of spherical moderator-detector systems for radiation protection monitoring

    International Nuclear Information System (INIS)

    Dhairyawan, M.P.

    1979-01-01

    Neutrons of energies below 500 keV are important from the point of view of radiation protection of personnel working around reactors. However, as no neutron sources are available at lower energies, no measured values of neutron energy response are available between thermal and 0.5 MeV (but for Sb-Be source at 24 keV). The response functions in this range are, therefore, arrived at theoretically. After giving a comprehensive review of the work done in the field of response of moderated neutron detectors, a Monte Carlo method developed for this purpose is described and used to calculate energy response functions of the two spherical moderator-detector systems, namely, one using a central BF 3 counter and the other using 6 LiI(Eu) scintillator of 0.490 dia crystal. The polythene sphere diameter ranged from 2'' to 12''. The results obtained follow the trend predicted by other calculations and experiments, but are a definite improvement over them, because the most recent data on cross sections and angular distribution are used and the opacity of the detector i.e. the presence and size of the detector within the moderator is taken into account in the present calculations. The reasons for the discrepancies in the present results and those obtained earlier by other methods are discussed. The response of the Leake counter arrived at by the present method agrees very well with experimental calibration. (M.G.B.)

  12. Computation of higher spherical harmonics moments of the angular flux for neutron transport problems in spherical geometry

    International Nuclear Information System (INIS)

    Sahni, D.C.; Sharma, A.

    2000-01-01

    The integral form of one-speed, spherically symmetric neutron transport equation with isotropic scattering is considered. Two standard problems are solved using normal mode expansion technique. The expansion coefficients are obtained by solving their singular integral equations. It is shown that these expansion coefficients provide a representation of all spherical harmonics moments of the angular flux as a superposition of Bessel functions. It is seen that large errors occur in the computation of higher moments unless we take certain precautions. The reasons for this phenomenon are explained. They throw some light on the failure of spherical harmonics method in treating spherical geometry problems as observed by Aronsson

  13. Neutron applications in materials for energy

    CERN Document Server

    Kearley, Gordon J

    2015-01-01

    Neutron Applications in Materials for Energy collects results and conclusions of recent neutron-based investigations of materials that are important in the development of sustainable energy. Chapters are authored by leading scientists with hands-on experience in the field, providing overviews, recent highlights, and case-studies to illustrate the applicability of one or more neutron-based techniques of analysis. The theme follows energy production, storage, and use, but each chapter, or section, can also be read independently, with basic theory and instrumentation for neutron scattering being

  14. Very High Energy Neutron Scattering from Hydrogen

    International Nuclear Information System (INIS)

    Cowley, R A; Stock, C; Bennington, S M; Taylor, J; Gidopoulos, N I

    2010-01-01

    The neutron scattering from hydrogen in polythene has been measured with the direct time-of flight spectrometer, MARI, at the ISIS facility of the Rutherford Appleton Laboratory with incident neutron energies between 0.5 eV and 600 eV. The results of experiments using the spectrometer, VESUVIO, have given intensities from hydrogen containing materials that were about 60% of the intensity expected from hydrogen. Since VESUVIO is the only instrument in the world that routinely operates with incident neutron energies in the eV range we have chosen to measure the scattering from hydrogen at high incident neutron energies with a different type of instrument. The MARI, direct time-of-flight, instrument was chosen for the experiment and we have studied the scattering for several different incident neutron energies. We have learnt how to subtract the gamma ray background, how to calibrate the incident energy and how to convert the spectra to an energy plot . The intensity of the hydrogen scattering was independent of the scattering angle for scattering angles from about 5 degrees up to 70 degrees for at least 3 different incident neutron energies between 20 eV and 100 eV. When the data was put on an absolute scale, by measuring the scattering from 5 metal foils with known thicknesses under the same conditions we found that the absolute intensity of the scattering from the hydrogen was in agreement with that expected to an accuracy of ± 5.0% over a wide range of wave-vector transfers between 1 and 250 A -1 . These measurements show that it is possible to measure the neutron scattering with incident neutron energies up to at least 100 eV with a direct geometry time-of-flight spectrometer and that the results are in agreement with conventional scattering theory.

  15. Transient neutrons flux behaviour in a spherical reactor core

    International Nuclear Information System (INIS)

    Souza, A.W.A. de.

    1978-11-01

    This work studies the transient neutron flux in a fast reactor of spherical geometry. The burning of U 235 nuclei is equated and two kinds of reflector were studied. The numeric solutions are then compared with the results for those reflectors. (author) [pt

  16. Prototype Neutron Energy Spectrometer

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  17. Prototype Neutron Energy Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Mitchell, Sanjoy Mukhopadhyay, Richard Maurer, Ronald Wolff

    2010-06-16

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

  18. Measurements of fusion neutron multiplication in spherical beryllium shells

    International Nuclear Information System (INIS)

    Giese, H.; Kappler, F.; Tayama, R.; Moellendorff, U. von; Alevra, A.; Klein, H.

    1996-01-01

    New results of spherical-shell transmission measurements with 14-MeV neutrons on pure beryllium shells up to 17 cm thick are reported. The spectral flux above 3 MeV was measured using a liquid scintillation detector. At 17 cm thickness, also the total neutron multiplication was measured using a Bonner sphere system. The results agree well with calculations using beryllium nuclear data from the EFF-1 or the ENDF/B-Vi library. (author). 23 refs, 4 figs, 1 tab

  19. Evaluation of mixed energy neutron doses using TLD NG-67 type

    International Nuclear Information System (INIS)

    Akhadi, Mukhlis; Thoyib Thamrin, M; Usmiyati Dewi, K.

    2000-01-01

    A research has been carried out to develop dose evaluation method of mixed neutron source with its neutron doses can be classified to two groups, I.e neutron doses with energy ≥ 0.5 eV and thermal neutron doses with energy less than 0.5 e V consist of epithermal and fast neutron, but in this research they were classified as fast neutron. Development of this dose evaluation method was carried out by sensitivity (S) intercomparison of TLD-600 to fast neutron, mixed energy neutron of nuclear rectors, and thermal neutron. From the experiment it was obtained that the value of Sfast : Sreactor : Sthermal = 0.005 : 0.010 : 1. Calibration factor (CF) of TLD is defined as 1/S. from the sensitivity data it can be obtained that the value of Cffast : Cfreactor : Cfthermal = 200 :100 : 1. The value of Cfreactor can be applied for mixed energy neutron doses evaluation of TLD-600. Key word : dosemeter, neutron dose, calibration factor, fast neutron, thermal neutron, nuclear reactor

  20. A test-type hyper-thermal neutron generator for neutron capture therapy - estimation of neutron energy spectrum by simulation calculations and TOF experiments

    International Nuclear Information System (INIS)

    Sakurai, Yoshinori; Kobayashi, Tooru; Kobayashi, Katsuhei

    1999-01-01

    In order to clarify the irradiation characteristics of hyper-thermal neutrons and the feasibility of a hyper-thermal neutron irradiation field for neutron capture therapy, a 'test-type' hyper-thermal neutron generator was designed and made. Graphite of 6 cm thickness and 21 cm diameter was selected as the high temperature scatterer. The scatterer is heated up to 1200 deg. C maximum using molybdenum heaters. The radiation heat is shielded by reflectors of molybdenum and stainless steel. The temperature is measured using three R-type thermo-couples and controlled by a program controller. The total thickness of the generator is designed to be as thin as possible, 20 cm in maximum, in the standing point of the neutron beam intensity. The thermal stability, controllability and safety of the generator at high temperature employment were confirmed by the heating tests. As one of the experiments for the characteristics estimation, the neutron energy spectrum dependent on the scatterer temperature was measured by the TOF (time of flight) method using the LINAC neutron generator. The estimations by simulation calculations were also performed. From the experiment and calculation results, it was confirmed that the neutron temperature shifted higher as the scatterer temperature was higher. The prospect of the feasibility of the 'hyper-thermal neutron irradiation field for NCT' was opened from the estimation results of the generator characteristics by the simulation calculations and experiments

  1. Spherical Harmonics Treatment of Epithermal Neutron Spectra in Reactor lattices

    International Nuclear Information System (INIS)

    Matausek, M.V.

    1972-04-01

    A procedure has been developed to solve the slowing down transport equation for neutrons in a cylindrized reactor lattice cell. Treating the anisotropy of the epithermal neutron flux by the spherical harmonics formalism, which reduces the space-angle-lethargy-dependent transport equation to the matrix integrodifferential equation in space and lethargy, and replacing the lethargy transfer integrals by finite-difference forms, a set of matrix ordinary differential equations, with lethargy and space dependent coefficients, is obtained. In the resonance region this set takes a lower block triangular form and can be directly solved by forward block substitution; in the lethargy range, where the fast fission effects have to be considered, the iterative procedure is introduced. A simple and efficient approximation is then proposed, making possible the analytical solution for the spatial dependence of the spherical harmonics flux moments. The proposed procedure has been numerically examined and approved. Some typical results are presented and discussed. (author)

  2. Proton energy dependence of slow neutron intensity

    International Nuclear Information System (INIS)

    Teshigawara, Makoto; Harada, Masahide; Watanabe, Noboru; Kai, Tetsuya; Sakata, Hideaki; Ikeda, Yujiro

    2001-01-01

    The choice of the proton energy is an important issue for the design of an intense-pulsed-spallation source. The optimal proton beam energy is rather unique from a viewpoint of the leakage neutron intensity but no yet clear from the slow-neutron intensity view point. It also depends on an accelerator type. Since it is also important to know the proton energy dependence of slow-neutrons from the moderators in a realistic target-moderator-reflector assembly (TMRA). We studied on the TMRA proposed for Japan Spallation Neutron Source. The slow-neutron intensities from the moderators per unit proton beam power (MW) exhibit the maximum at about 1-2 GeV. At higher proton energies the intensity per MW goes down; at 3 and 50 GeV about 0.91 and 0.47 times as low as that at 1 GeV. The proton energy dependence of slow-neutron intensities was found to be almost the same as that of total neutron yield (leakage neutrons) from the same bare target. It was also found that proton energy dependence was almost the same for the coupled and decoupled moderators, regardless the different moderator type, geometry and coupling scheme. (author)

  3. Interrelation between the isoscalar octupole phonon and the proton-neutron mixed-symmetry quadrupole phonon in near-spherical nuclei

    International Nuclear Information System (INIS)

    Smirnova, N.A.; Van Isacker, P.; Smirnova, N.A; Pietralla, N.; Yale Univ., New Haven, CT; Mizusaki, T.

    2000-01-01

    The interrelation between the octupole phonon and the low-lying proton-neutron mixed-symmetry quadrupole in near-spherical nuclei is investigated. The one-phonon states decay by collective E3 and E2 transitions to the ground state and by relatively strong E1 and M1 transitions to the isoscalar 2 + 1 state. We apply the proton-neutron version of the Interacting Boson Model including quadrupole and octupole bosons (sdf-IBM-2). Two F-spin symmetric dynamical symmetry limits of the model, namely the vibrational and the γ-unstable ones, are considered. We derived analytical formulae for excitation energies as well as B(E1), B(M1), B(E2), and B(E3) values for a number of transitions between low-lying states. The model well reproduces many known transition strengths in the near spherical nuclei 142 Ce and 94 Mo. (authors)

  4. Interrelation between the isoscalar octupole phonon and the proton-neutron mixed-symmetry quadrupole phonon in near-spherical nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Smirnova, N.A.; Van Isacker, P. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France); Smirnova, N.A [Paris-11 Univ., 91 - Orsay (France). Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse]|[Institute for Nuclear Physics, Moscow State University (Russian Federation); Pietralla, N. [Institut fur Kernphysik, Universitat zu Koln (Germany)]|[Yale Univ., New Haven, CT (United States). Wright Nuclear Structure Lab; Mizusaki, T. [Tokyo Univ. (Japan). Dept. of Physics

    2000-07-01

    The interrelation between the octupole phonon and the low-lying proton-neutron mixed-symmetry quadrupole in near-spherical nuclei is investigated. The one-phonon states decay by collective E3 and E2 transitions to the ground state and by relatively strong E1 and M1 transitions to the isoscalar 2{sup +}{sub 1} state. We apply the proton-neutron version of the Interacting Boson Model including quadrupole and octupole bosons (sdf-IBM-2). Two F-spin symmetric dynamical symmetry limits of the model, namely the vibrational and the {gamma}-unstable ones, are considered. We derived analytical formulae for excitation energies as well as B(E1), B(M1), B(E2), and B(E3) values for a number of transitions between low-lying states. The model well reproduces many known transition strengths in the near spherical nuclei {sup 142}Ce and {sup 94}Mo. (authors)

  5. Neutronics design for a spherical tokamak fusion-transmutation reactor

    International Nuclear Information System (INIS)

    Deng Meigen; Feng Kaiming; Yang Bangchao

    2002-01-01

    Based on studies of the spherical tokamak fusion reactors, a concept of fusion-transmutation reactor is put forward. By using the one-dimension transport and burn-up code BISON3.0 to process optimized design, a set of plasma parameters and blanket configuration suitable for the transmutation of MA (Minor Actinides) nuclear waste is selected. Based on the one-dimension calculation, two-dimension calculation has been carried out by using two-dimension neutronics code TWODANT. Combined with the neutron flux given by TWODANT calculation, burn-up calculation has been processed by using the one-dimension radioactivity calculation code FDKR and some useful and reasonable results are obtained

  6. Laser driven compression and neutron generation with spherical shell targets

    International Nuclear Information System (INIS)

    Campbell, P.M.; Hammerling, P.; Johnson, R.R.; Kubis, J.J.; Mayer, F.J.

    1977-01-01

    Laser-driven implosion experiments using DT-gas-filled spherical glass-shell targets are described. Neutron yields to 5 x 10 7 are produced from implosions of small ( -- 55 μm-diameter) targets spherically illuminated with an on-target laser power of 0.4 terawatt. Nuclear reaction product diagnostics, X-ray pinhole photographs, fast-ion spectra and X-ray measurements are used in conjunction with hydrodynamic computer code simulations to investigate the implosion phenomenology as well as the target corona evolution. Simulations using completely classical effects are not able to describe the full range of experimental data. Electron or radiation preheating may be required to explain some implosion measurements. (auth.)

  7. Low energy neutrons from a sup 2 sup 3 sup 9 PuBe isotopic neutron source inserting in moderating media

    CERN Document Server

    Vega, H R

    2002-01-01

    Several neutron applications share a common problem: the neutron source design. In this work MCNP computer code has been used to design a moderated sup 2 sup 3 sup 9 PuBe neutron source to produce low energy neutrons. The design involves the source located at the center of a spherical moderator. Moderator media studied were light water, heavy water and a heterogeneous combination of light water and heavy water. Similar moderating features were found between the 24.5 cm-radius container filled with heavy water (23.0-cm-thick) and that made with light water (3.5-cm-thick) plus heavy water (19.5-cm-thick). A sup 2 sup 3 sup 9 PuBe neutron source inserted in this moderator produces, at 27 cm, a neutron fluence of 1.8 x 10 sup - sup 4 n-cm sup - sup 2 per source neutron, with an average neutron energy of 0.34 MeV, where 47.8 % have an energy <= 0.4 eV. A further study of this moderator was carried out using a reflector medium made of graphite. Thus, 15-cm-thickness reflector improves the neutron field producing...

  8. Spectral correction factors for conventional neutron dose meters used in high-energy neutron environments improved and extended results based on a complete survey of all neutron spectra in IAEA-TRS-403

    International Nuclear Information System (INIS)

    Oparaji, U.; Tsai, Y. H.; Liu, Y. C.; Lee, K. W.; Patelli, E.; Sheu, R. J.

    2017-01-01

    This paper presents improved and extended results of our previous study on corrections for conventional neutron dose meters used in environments with high-energy neutrons (E n > 10 MeV). Conventional moderated-type neutron dose meters tend to underestimate the dose contribution of high-energy neutrons because of the opposite trends of dose conversion coefficients and detection efficiencies as the neutron energy increases. A practical correction scheme was proposed based on analysis of hundreds of neutron spectra in the IAEA-TRS-403 report. By comparing 252 Cf-calibrated dose responses with reference values derived from fluence-to-dose conversion coefficients, this study provides recommendations for neutron field characterization and the corresponding dose correction factors. Further sensitivity studies confirm the appropriateness of the proposed scheme and indicate that (1) the spectral correction factors are nearly independent of the selection of three commonly used calibration sources: 252 Cf, 241 Am-Be and 239 Pu-Be; (2) the derived correction factors for Bonner spheres of various sizes (6''-9'') are similar in trend and (3) practical high-energy neutron indexes based on measurements can be established to facilitate the application of these correction factors in workplaces. (authors)

  9. Cellular neural network to the spherical harmonics approximation of neutron transport equation in x–y geometry

    International Nuclear Information System (INIS)

    Pirouzmand, Ahmad; Hadad, Kamal

    2012-01-01

    Highlights: ► This paper describes the solution of time-dependent neutron transport equation. ► We use a novel method based on cellular neural networks (CNNs) coupled with the spherical harmonics method. ► We apply the CNN model to simulate step and ramp perturbation transients in a core. ► The accuracy and capabilities of the CNN model are examined for x–y geometry. - Abstract: In an earlier paper we utilized a novel method using cellular neural networks (CNNs) coupled with spherical harmonics method to solve the steady state neutron transport equation in x–y geometry. Here, the previous work is extended to the study of time-dependent neutron transport equation. To achieve this goal, an equivalent electrical circuit based on a second-order form of time-dependent neutron transport equation and one equivalent group of neutron precursor density is obtained by the CNN method. The CNN model is used to simulate step and ramp perturbation transients in a typical 2D core.

  10. Spatial fluxes and energy distributions of reactor fast neutrons in two types of heat resistant concretes

    International Nuclear Information System (INIS)

    Akki, T.S.; Benayad, S.A.; Megahid, R.M.

    1992-01-01

    Measurements have been carried out to study the spatial fluxes and energy distributions of reactor fast neutrons transmitted through two types of heat resistant concretes, serpentine concrete and magnetic lemonite concrete. The physical, chemical and mechanical properties of these concretes were checked by well known techniques. In addition, the effect of heating at temperatures up to 500deg C on the crystaline water content was checked by the method of differential thermal analysis. Measurements were performed using a collimated beam of reactor neutrons emitted from a 10 MW research reactor. The neutron spectra transmitted through concrete barriers of different thickness were measured by a scintillation spectrometer with NE-213 liquid organic scintillator. Discrimination against undesired pulses due to gamma-rays was achieved by a method based on pulse shape discrimination technique. The operating principle of this technique is based on the comparison of two weighted time integrals of the detector signal. The measured pulse amplitude distribution was converted to neutron energy distribution by a computational code based on double differentiation technique. The spectrometer workability and the accuracy of the unfolding technique were checked by measuring the neutron spectra of neutrons from Pu-α-Be and 252 Cf neutron sources. The obtained neutron spectra for the two concretes were used to derive the total cross sections for neutrons of different energies. (orig.)

  11. Intercomparison of medium-energy neutron attenuation in iron and concrete

    International Nuclear Information System (INIS)

    Hirayama, H.

    1999-01-01

    Neutron attenuation of medium energy below 1 GeV has not been well understood until now. It is desired to obtain common agreements concerning the behaviours of neutrons inside various materials. This is necessary in order to agree on definitions of the attenuation length, which is very important for shielding calculations involving high energy accelerators. As one attempt, it was proposed by Japanese attendants of SATIF-2 to compare the attenuation of medium-energy neutrons inside iron and concrete shields between various computer codes and data, and was cited as a suitable action for SATIF. The first results from three groups were presented at SATIF-3. It has become clear that neutrons above 20 MeV are important for understanding the attenuation inside materials and that the geometry, planar or spherical, does not affect the results very much. Considering the CPU times required for Monte Carlo calculations and this result, revised problems to be calculated were prepared by the Japanese Working Group and sent to the participants of this action. The geometry is only plane, and calculations are required only for neutrons above 20 MeV. The secondary neutrons from high energy protons, which were calculated by H. Nakashima, are also included in the problem. The results from four groups were sent to the organizer at the end of August. This paper presents a comparison between groups concerning the attenuation length together with the neutron spectrum and the future themes which come from this intercomparison. (author)

  12. Model-Independent Calculation of Radiative Neutron Capture on Lithium-7

    NARCIS (Netherlands)

    Rupak, Gautam; Higa, Renato

    2011-01-01

    The radiative neutron capture on lithium-7 is calculated model independently using a low-energy halo effective field theory. The cross section is expressed in terms of scattering parameters directly related to the S-matrix elements. It depends on the poorly known p-wave effective range parameter

  13. Response of CR-39 SSNTD to high energy neutrons using zirconium convertors - a Monte Carlo and experimental study

    International Nuclear Information System (INIS)

    Pal, Rupali; Sapra, B.K.; Bakshi, A.K.; Datta, D.; Biju, K.; Suryanarayana, S.V.; Nayak, B.K.

    2016-01-01

    Neutron dosimetry in ion accelerators is a challenging field as the neutron spectrum varies from thermal, to fast and high-energy neutrons usually extending beyond 20 MeV. Solid-state Nuclear Track Detectors (SSNTDs) have been increasingly used in numerous fields related to nuclear physics. Extensive work has also been carried out on determining the response characteristics of such detectors as nuclear spectrometers. In nuclear reaction studies, identification of reaction products according to their type and energy is frequently required. For normally incident particles, energy-dispersive track-diameter methods have become useful scientific tools using CR-39 SSNTD. CR-39 along with 1 mm polyethylene convertor can cover a neutron energy range from 100 keV to 10 MeV. The neutron interacts with the hydrogen in CR-39 producing recoil protons from elastic collisions. This detectable neutron energy range can be increased by modification in the radiator/convertor used along with CR-39. CR39 detectors placed in conjunction with judiciously chosen thicknesses of a polyethylene radiator and a lead absorber (or degrader) are used to increase energy range upto 19 MeV. A portable neutron counter has been proposed for high-energy neutron measurement with 1 cm thick Zirconium (Zr) as the converter outside a spherical HDPE shell of 7 inch diameter. Zr metal has been found to show (n,2n) cross section for energies above 10 MeV starting from 0.01 barns for 8 MeV upto 1 barns for 22 MeV. Above these energies, the experimental data is scarce. In this paper, Zr was used in conjunction with CR-39 which showed an enhancement of track density on the CR-39. This paper demonstrates the enhancement of neutron response using Zr on CR-39 with both theoretical and experimental studies

  14. Intercomparison of high energy neutron personnel dosimeters

    International Nuclear Information System (INIS)

    McDonald, J.C.; Akabani, G.; Loesch, R.M.

    1993-03-01

    An intercomparison of high-energy neutron personnel dosimeters was performed to evaluate the uniformity of the response characteristics of typical neutron dosimeters presently in use at US Department of Energy (DOE) accelerator facilities. It was necessary to perform an intercomparison because there are no national or international standards for high-energy neutron dosimetry. The testing that is presently under way for the Department of Energy Laboratory Accreditation Program (DOELAP) is limited to the use of neutron sources that range in energy from about 1 keV to 2 MeV. Therefore, the high-energy neutron dosimeters presently in use at DOE accelerator facilities are not being tested effectively. This intercomparison employed neutrons produced by the 9 Be(p,n) 9 B interaction at the University of Washington cyclotron, using 50-MeV protons. The resulting neutron energy spectrum extended to a maximum of approximately 50-MeV, with a mean energy of about 20-MeV. Intercomparison results for currently used dosimeters, including Nuclear Type A (NTA) film, thermoluminescent dosimeter (TLD)-albedo, and track-etch dosimeters (TEDs), indicated a wide variation in response to identical doses of high-energy neutrons. Results of this study will be discussed along with a description of plans for future work

  15. Continuous energy Neutron Transport Monte Carlo Simulator Project: Decomposition of the neutron energy spectrum by target nuclei tagging

    Energy Technology Data Exchange (ETDEWEB)

    Barcellos, Luiz Felipe F.C.; Bodmann, Bardo E.J.; Vilhena, Marco T.M.B., E-mail: luizfelipe.fcb@gmail.com, E-mail: bardo.bodmann@ufrgs.br, E-mail: mtmbvilhena@gmail.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Grupo de Estudos Nucleares; Leite, Sergio Q. Bogado, E-mail: sbogado@ibest.com.br [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)

    2017-07-01

    In this work a Monte Carlo simulator with continuous energy is used. This simulator distinguishes itself by using the sum of three probability distributions to represent the neutron spectrum. Two distributions have known shape, but have varying population of neutrons in time, and these are the fission neutron spectrum (for high energy neutrons) and the Maxwell-Boltzmann distribution (for thermal neutrons). The third distribution has an a priori unknown and possibly variable shape with time and is determined from parametrizations of Monte Carlo simulation. It is common practice in neutron transport calculations, e.g. multi-group transport, to consider that the neutrons only lose energy with each scattering reaction and then to use a thermal group with a Maxwellian distribution. Such an approximation is valid due to the fact that for fast neutrons up-scattering occurrence is irrelevant, being only appreciable at low energies, i.e. in the thermal energy region, in which it can be regarded as a Maxwell-Boltzmann distribution for thermal equilibrium. In this work the possible neutron-matter interactions are simulated with exception of the up-scattering of neutrons. In order to preserve the thermal spectrum, neutrons are selected stochastically as being part of the thermal population and have an energy attributed to them taken from a Maxwellian distribution. It is then shown how this procedure can emulate the up-scattering effect by the increase in the neutron population kinetic energy. Since the simulator uses tags to identify the reactions it is possible not only to plot the distributions by neutron energy, but also by the type of interaction with matter and with the identification of the target nuclei involved in the process. This work contains some preliminary results obtained from a Monte Carlo simulator for neutron transport that is being developed at Federal University of Rio Grande do Sul. (author)

  16. Low energy neutron scattering for energy dependent cross sections. General considerations

    Energy Technology Data Exchange (ETDEWEB)

    Rothenstein, W; Dagan, R [Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Mechanical Engineering

    1996-12-01

    We consider in this paper some aspects related to neutron scattering at low energies by nuclei which are subject to thermal agitation. The scattering is determined by a temperature dependent joint scattering kernel, or the corresponding joint probability density, which is a function of two variables, the neutron energy after scattering, and the cosine of the angle of scattering, for a specified energy and direction of motion of the neutron, before the interaction takes place. This joint probability density is easy to calculate, when the nucleus which causes the scattering of the neutron is at rest. It can be expressed by a delta function, since there is a one to one correspondence between the neutron energy change, and the cosine of the scattering angle. If the thermal motion of the target nucleus is taken into account, the calculation is rather more complicated. The delta function relation between the cosine of the angle of scattering and the neutron energy change is now averaged over the spectrum of velocities of the target nucleus, and becomes a joint kernel depending on both these variables. This function has a simple form, if the target nucleus behaves as an ideal gas, which has a scattering cross section independent of energy. An energy dependent scattering cross section complicates the treatment further. An analytic expression is no longer obtained for the ideal gas temperature dependent joint scattering kernel as a function of the neutron energy after the interaction and the cosine of the scattering angle. Instead the kernel is expressed by an inverse Fourier Transform of a complex integrand, which is averaged over the velocity spectrum of the target nucleus. (Abstract Truncated)

  17. Upgrade of neutron energy spectrometer with single multilayer bonner sphere using onion-like structure

    International Nuclear Information System (INIS)

    Mizukpshi, Tomoaki; Watanabe, Kenichi; Yamazaki, Atsushi; Uritan, Akira; Iguchi, Tetsuo; Ogata, Tomohiro; Muramatsu, Takashi

    2016-01-01

    In order to measure neutron energy spectra, the conventional Bonner Sphere Spectrometers (BSS) are widely used. In this spectrometer, several measurements with different size Bonner spheres are required. Operators should, therefore, place these spheres in several times to a measurement point where radiation dose might be relatively high. In order to reduce this effort, novel neutron energy spectrometer using an onion-like single Bonner sphere was proposed in our group. This Bonner sphere has multiple sensitive spherical shell layers in the single sphere. In this spectrometer, a band-shaped thermal neutron detection medium, which consists of a LiF-ZnS mixed powder scintillator sheet and a wavelength-shifting (WLS) fiber readout, was looped to each sphere at equal angular intervals. Amount of LiF neutron converter is reduced near polar region, where the band-shaped detectors are concentrated, in order to uniform the directional sensitivity. The LiF-ZnS mixed powder has an advantage of extremely high light yield. However, since it is opaque, scintillation photons cannot be collect uniformly. This type of detector shows no characteristic shape in the pulse height spectrum. Subsequently, it is difficult to set the pulse height discrimination level. This issue causes sensitivity fluctuation due to gain instability of photodetectors and/or electric modules. In order to solve this problem, we propose to replace the LiF-ZnS mixed powder into a flexible and Transparent RUbber SheeT type LiCaAlF6 (TRUST LiCAF) scintillator. TRUST LiCAF scintillator can show a peak shape corresponding to neutron absorption events in the pulse height spectrum. We fabricated the prototype detector with five sensitive layers using TRUST LiCAF scintillator and conducted basic experiments to evaluate the directional uniformity of the sensitivity. The fabricated detector shows excellent directional uniformity of the neutron sensitivity

  18. Neutron Spin Resonance in the 112-Type Iron-Based Superconductor

    Science.gov (United States)

    Xie, Tao; Gong, Dongliang; Ghosh, Haranath; Ghosh, Abyay; Soda, Minoru; Masuda, Takatsugu; Itoh, Shinichi; Bourdarot, Frédéric; Regnault, Louis-Pierre; Danilkin, Sergey; Li, Shiliang; Luo, Huiqian

    2018-03-01

    We use inelastic neutron scattering to study the low-energy spin excitations of the 112-type iron pnictide Ca0.82La0.18Fe0.96Ni0.04As2 with bulk superconductivity below Tc=22 K . A two-dimensional spin resonance mode is found around E =11 meV , where the resonance energy is almost temperature independent and linearly scales with Tc along with other iron-based superconductors. Polarized neutron analysis reveals the resonance is nearly isotropic in spin space without any L modulations. Because of the unique monoclinic structure with additional zigzag arsenic chains, the As 4 p orbitals contribute to a three-dimensional hole pocket around the Γ point and an extra electron pocket at the X point. Our results suggest that the energy and momentum distribution of the spin resonance does not directly respond to the kz dependence of the fermiology, and the spin resonance intrinsically is a spin-1 mode from singlet-triplet excitations of the Cooper pairs in the case of weak spin-orbital coupling.

  19. Spectral correction factors for conventional neutron dosemeters used in high-energy neutron environments

    International Nuclear Information System (INIS)

    Lee, K.W.; Sheu, R.J.

    2015-01-01

    High-energy neutrons (>10 MeV) contribute substantially to the dose fraction but result in only a small or negligible response in most conventional moderated-type neutron detectors. Neutron dosemeters used for radiation protection purpose are commonly calibrated with 252 Cf neutron sources and are used in various workplace. A workplace-specific correction factor is suggested. In this study, the effect of the neutron spectrum on the accuracy of dose measurements was investigated. A set of neutron spectra representing various neutron environments was selected to study the dose responses of a series of Bonner spheres, including standard and extended-range spheres. By comparing 252 Cf-calibrated dose responses with reference values based on fluence-to-dose conversion coefficients, this paper presents recommendations for neutron field characterisation and appropriate correction factors for responses of conventional neutron dosemeters used in environments with high-energy neutrons. The correction depends on the estimated percentage of high-energy neutrons in the spectrum or the ratio between the measured responses of two Bonner spheres (the 4P6-8 extended-range sphere versus the 6'' standard sphere). (authors)

  20. Proton-neutron sdg boson model and spherical-deformed phase transition

    Science.gov (United States)

    Otsuka, Takaharu; Sugita, Michiaki

    1988-12-01

    The spherical-deformed phase transition in nuclei is described in terms of the proton-neutron sdg interacting boson model. The sdg hamiltonian is introduced to model the pairing+quadrupole interaction. The phase transition is reproduced in this framework as a function of the boson number in the Sm isotopes, while all parameters in the hamiltonian are kept constant at values reasonable from the shell-model point of view. The sd IBM is derived from this model through the renormalization of g-boson effects.

  1. Proton-neutron sdg boson model and spherical-deformed phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Otsuka, Takaharu; Sugita, Michiaki

    1988-12-15

    The spherical-deformed phase transition in nuclei is described in terms of the proton-neutron sdg interacting boson model. The sdg hamiltonian is introduced to model the pairing + quadrupole interaction. The phase transition is reproduced in this framework as a function of the boson number in the Sm isotopes, while all parameters in the hamiltonian are kept constant at values reasonable from the shell-model point of view. The sd IBM is derived from this model through the renormalization of g-boson effects.

  2. High energy neutron radiography

    International Nuclear Information System (INIS)

    Gavron, A.; Morley, K.; Morris, C.; Seestrom, S.; Ullmann, J.; Yates, G.; Zumbro, J.

    1996-01-01

    High-energy spallation neutron sources are now being considered in the US and elsewhere as a replacement for neutron beams produced by reactors. High-energy and high intensity neutron beams, produced by unmoderated spallation sources, open potential new vistas of neutron radiography. The authors discuss the basic advantages and disadvantages of high-energy neutron radiography, and consider some experimental results obtained at the Weapons Neutron Research (WNR) facility at Los Alamos

  3. Studies of spherical inertial-electrostatic confinement

    International Nuclear Information System (INIS)

    Miley, G.H.

    1992-01-01

    Theoretical and experimental results from studies of Spherical Inertial-Electrostatic Confinement (SIEC) are presented. This principle of IEC involves the confinement by multiple potential wells created by ion injection into a spherical device containing biased grids. A semitransparent cathode accelerates ions, generating a spherical ion-beam flow which converges at the center of the spherical volume, creating a space charge (potential well) region. An electron flow is created by the core (virtual anode) region, forming in turn a virtual cathode. Ions trapped inside this well oscillate back and forth until they fuse or degrade in energy. Such multiple wells with virtual anodes and cathodes, have been called ''Poissors'' following the original work by Farnsworth and by Hirsch. Fusion within the core occurs by reactions between non-Maxwellian beam-beam type ions. This has the potential for achieving a high power density and also for burning both D-T and advanced fuels. If successful, such a device would be attractive for a variety of high power density applications, e.g., space power or as a neutron source based on D-D or D-T operation. Simulations of recent SIEC experiments have been carried out using the XL-code, to solve Poisson's equation, self-consistently with the collisionless Vlasov equation in spherical geometry for several current species and grid parameters. The potential profile predictions are reasonably consistent with experimental results. Potential well measurements used a collimated proton detector. Results indicate that an ∼ 15-kV virtual anode, at least one centimeter in radius, was formed in a spherical device with a cathode potential of 30 kV using an ion current of ∼ 30 mA. Analysis indicates D + densities on the order of 10 9 cm -3 , and D 2 + densities on the order of 10 10 cm -3 . Steady-state D-D neutron emission of about 10 6 n/sec is observed

  4. Neutron matter, symmetry energy and neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Stefano, Gandolfi [Los Alamos National Laboratory (LANL); Steiner, Andrew W [ORNL

    2016-01-01

    Recent progress in quantum Monte Carlo with modern nucleon-nucleon interactions have enabled the successful description of properties of light nuclei and neutron-rich matter. Of particular interest is the nuclear symmetry energy, the energy cost of creating an isospin asymmetry, and its connection to the structure of neutron stars. Combining these advances with recent observations of neutron star masses and radii gives insight into the equation of state of neutron-rich matter near and above the saturation density. In particular, neutron star radius measurements constrain the derivative of the symmetry energy.

  5. Force chains in monodisperse spherical particle assemblies: Three-dimensional measurements using neutrons

    Science.gov (United States)

    Wensrich, C. M.; Kisi, E. H.; Luzin, V.; Garbe, U.; Kirstein, O.; Smith, A. L.; Zhang, J. F.

    2014-10-01

    The full triaxial stress state within individual particles in a monodisperse spherical granular assembly has been measured. This was made possible by neutron imaging and computed tomography combined with neutron diffraction strain measurement techniques and associated stress reconstruction. The assembly in question consists of 549 precision steel ball bearings under an applied axial load of 85 MPa in a cylindrical die. Clear evidence of force chains was observed in terms of both the shape of the probability distribution function for normal stresses and the network formed by highly loaded particles. An extensive analysis of the source and magnitude of uncertainty in these measurements is also presented.

  6. Type II critical phenomena of neutron star collapse

    International Nuclear Information System (INIS)

    Noble, Scott C.; Choptuik, Matthew W.

    2008-01-01

    We investigate spherically symmetric, general relativistic systems of collapsing perfect fluid distributions. We consider neutron star models that are driven to collapse by the addition of an initially 'ingoing' velocity profile to the nominally static star solution. The neutron star models we use are Tolman-Oppenheimer-Volkoff solutions with an initially isentropic, gamma law equation of state. The initial values of (1) the amplitude of the velocity profile, and (2) the central density of the star, span a parameter space, and we focus only on that region that gives rise to type II critical behavior, wherein black holes of arbitrarily small mass can be formed. In contrast to previously published work, we find that--for a specific value of the adiabatic index (Γ=2)--the observed type II critical solution has approximately the same scaling exponent as that calculated for an ultrarelativistic fluid of the same index. Further, we find that the critical solution computed using the ideal-gas equations of state asymptotes to the ultrarelativistic critical solution.

  7. Proton-neutron sdg boson model and spherical-deformed phase transition

    International Nuclear Information System (INIS)

    Otsuka, Takaharu; Sugita, Michiaki

    1988-01-01

    The spherical-deformed phase transition in nuclei is described in terms of the proton-neutron sdg interacting boson model. The sdg hamiltonian is introduced to model the pairing + quadrupole interaction. The phase transition is reproduced in this framework as a function of the boson number in the Sm isotopes, while all parameters in the hamiltonian are kept constant at values reasonable from the shell-model point of view. The sd IBM is derived from this model through the renormalization of g-boson effects. (orig.)

  8. A new/old type of neutron spectrometer

    International Nuclear Information System (INIS)

    Vylet, V.; Fasso, A.; Luckau, N.

    1998-01-01

    The proposed portable spectrometer is a large sphere made of a plastic scintillator loaded with boron, possibly enriched with boron 10. The sphere is divided into spherical shells coated with a reflective or opaque material. Each shell is made of two hemispherical shells or smaller segments. Each segment is connected by a light-guide to a photomultiplier or a photodiode. It might be possible to use miniature photomultipliers directly embedded in detector layers. Each shell measures the thermal fluence at a different moderator depth and the set of shell responses can be used to unfold the original neutron spectrum, covering the range of energies from thermal to 20 MeV. (M.D.)

  9. Dynamic deformation theory of spherical and deformed light and heavy nuclei with A = 12-240

    International Nuclear Information System (INIS)

    Kumar, Krishna.

    1979-01-01

    Deformation dependent wave functions are calculated for different types of even-even nuclei (spherical, transitional, deformed; light, medium, heavy) without any fitting parameters. These wave functions are employed for the energies, B(E2)'s, quadrupole and magnetic moments of selected nuclei with A = 12-240 (with special emphasis on 56 Fe, 154 Gd), and for neutron cross sections of 148 Sm, 152 Sm

  10. Computer aided design of fast neutron therapy units

    International Nuclear Information System (INIS)

    Gileadi, A.E.; Gomberg, H.J.; Lampe, I.

    1980-01-01

    Conceptual design of a radiation-therapy unit using fusion neutrons is presently being considered by KMS Fusion, Inc. As part of this effort, a powerful and versatile computer code, TBEAM, has been developed which enables the user to determine physical characteristics of the fast neutron beam generated in the facility under consideration, using certain given design parameters of the facility as inputs. TBEAM uses the method of statistical sampling (Monte Carlo) to solve the space, time and energy dependent neutron transport equation relating to the conceptual design described by the user-supplied input parameters. The code traces the individual source neutrons as they propagate throughout the shield-collimator structure of the unit, and it keeps track of each interaction by type, position and energy. In its present version, TBEAM is applicable to homogeneous and laminated shields of spherical geometry, to collimator apertures of conical shape, and to neutrons emitted by point sources or such plate sources as are used in neutron generators of various types. TBEAM-generated results comparing the performance of point or plate sources in otherwise identical shield-collimator configurations are presented in numerical form. (H.K.)

  11. Investigating The Neutron Flux Distribution Of The Miniature Neutron Source Reactor MNSR Type

    International Nuclear Information System (INIS)

    Nguyen Hoang Hai; Do Quang Binh

    2011-01-01

    Neutron flux distribution is the important characteristic of nuclear reactor. In this article, four energy group neutron flux distributions of the miniature neutron source reactor MNSR type versus radial and axial directions are investigated in case the control rod is fully withdrawn. In addition, the effect of control rod positions on the thermal neutron flux distribution is also studied. The group constants for all reactor components are generated by the WIMSD code, and the neutron flux distributions are calculated by the CITATION code. The results show that the control rod positions only affect in the planning area for distribution in the region around the control rod. (author)

  12. The tensor part of the Skyrme energy density functional. I. Spherical nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Lesinski, T.; Meyer, J. [Universite de Lyon, F-69003 Lyon (France)]|[Institut de Physique Nucleaire de Lyon, CNRS/IN2P3, Universite Lyon 1, F-69622 Villeurbanne (France); Bender, M. [DSM/DAPNIA/SPhN, CEA Saclay, F-91191 Gif-sur-Yvette Cedex (France)]|[Universite Bordeaux, CNRS/IN2P3, Centre d' Etudes Nucleaires de Bordeaux Gradignan, UMR5797, Chemin du Solarium, BP120, F-33175 Gradignan (France); Bennaceur, K. [Universite de Lyon, F-69003 Lyon (France)]|[Institut de Physique Nucleaire de Lyon, CNRS/IN2P3, Universite Lyon 1, F-69622 Villeurbanne (France)]|[DSM/DAPNIA/SPhN, CEA Saclay, F-91191 Gif-sur-Yvette Cedex (France); Duguet, T. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

    2007-04-15

    We perform a systematic study of the impact of the J-vector{sup 2} tensor term in the Skyrme energy functional on properties of spherical nuclei. In the Skyrme energy functional, the tensor terms originate both from zero-range central and tensor forces. We build a set of 36 parameterizations which cover a wide range of the parameter space of the isoscalar and isovector tensor term coupling constants with a fit protocol very similar to that of the successful SLy parameterizations. We analyze the impact of the tensor terms on a large variety of observables in spherical mean-field calculations, such as the spin-orbit splittings and single-particle spectra of doubly-magic nuclei, the evolution of spin-orbit splittings along chains of semi-magic nuclei, mass residuals of spherical nuclei, and known anomalies of radii. The major findings of our study are (i) tensor terms should not be added perturbatively to existing parameterizations, a complete refit of the entire parameter set is imperative. (ii) The free variation of the tensor terms does not lower the {chi}{sup 2} within a standard Skyrme energy functional. (iii) For certain regions of the parameter space of their coupling constants, the tensor terms lead to instabilities of the spherical shell structure, or even the coexistence of two configurations with different spherical shell structure. (iv) The standard spin-orbit interaction does not scale properly with the principal quantum number, such that single-particle states with one or several nodes have too large spin-orbit splittings, while those of node-less intruder levels are tentatively too small. Tensor terms with realistic coupling constants cannot cure this problem. (v) Positive values of the coupling constants of proton-neutron and like-particle tensor terms allow for a qualitative description of the evolution of spin-orbit splittings in chains of Ca, Ni and Sn isotopes. (vi) For the same values of the tensor term coupling constants, however, the overall

  13. Preliminary results of total kinetic energy modelling for neutron-induced fission

    International Nuclear Information System (INIS)

    Visan, I.; Giubega, G.; Tudora, A.

    2015-01-01

    The total kinetic energy as a function of fission fragments mass TKE(A) is an important quantity entering in prompt emission calculations. The experimentally distributions of TKE(A) are referring to a limited number of fission systems and incident energies. In the present paper, a preliminary model for TKE calculation in neutron induced fission system is presented. The range of fission fragments is chosen as in the Point by Point treatment. The model needs as input only mass excesses and deformation parameters taken from available nuclear databases being based on the following approximations: total excitation energy of fully accelerated fission fragments TXE is calculated from energy balance of neutron-induced fission systems as sum of the total excitation energy at scission E*sciss and deformation energy Edef. The deformation energy at scission is given by minimizing the potential energy at the scission configuration. At the scission point, the fission system is described by two spheroidal fragments nearly touching by a pre-scission distance or neck caused by the nuclear forces between fragments. Therefore, the Columbian repulsion depending on neck and, consequently, on the fragments deformation at scission, is essentially in TKE determination. An approximation is made based on the fission modes. For the very symmetric fission, the dominant super long channel is characterized by long distance between fragments leading to low TKE values. Due to magic and double-magic shells closure, the dominant S1 fission mode for pairs with heavy fragment mass AH around 130-134 is characterized by spherical heavy fragment shape and easily deformed light fragment. The nearly spherical shape of the complementary fragments are characterized by minimum distance, and consequently to maximum TKE values. The results obtained for TKE(A) are in good agreement with existing experimental data for many neutron induced fission systems, e.g. ''2''3''3&apos

  14. Use of a Boron Doped Spherical Phantom for the Investigation of Neutron Directional Properties: Comparison Between Experiment and MCNP Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Drake, P.; Kierkegaard, J

    1999-07-01

    A boron doped 19 cm diameter spherical phantom was constructed to give information on the direction of neutrons inside the Ringhals 4 containment. The phantom was made of 40% paraffin and 60% boric acid. 10B contributes 2% of the total phantom weight. The phantom was tested for its angular sensitivity to neutrons. The response was tested with a {sup 252}Cf source and with a Monte Carlo calculation (MCNP) simulating a {sup 252}Cf source. In these investigations the phantom showed a strong directional response. However, there was only a fair correspondence between the experiment and the simulation. The discrepancies are, at least in part, due to the difference in energy and angular response of the dosemeters as compared with the idealised response characteristics in the MCNP calculation. In the MCNP calculation the experimental conditions were not fully simulated. The investigations also showed that the addition of boron to the phantom reduces the leakage of thermalised neutrons from the phantom, and the production of neutron induced photons in the phantom to insignificant levels. (author)

  15. Use of a Boron Doped Spherical Phantom for the Investigation of Neutron Directional Properties: Comparison Between Experiment and MCNP Simulation

    International Nuclear Information System (INIS)

    Drake, P.; Kierkegaard, J.

    1999-01-01

    A boron doped 19 cm diameter spherical phantom was constructed to give information on the direction of neutrons inside the Ringhals 4 containment. The phantom was made of 40% paraffin and 60% boric acid. 10B contributes 2% of the total phantom weight. The phantom was tested for its angular sensitivity to neutrons. The response was tested with a 252 Cf source and with a Monte Carlo calculation (MCNP) simulating a 252 Cf source. In these investigations the phantom showed a strong directional response. However, there was only a fair correspondence between the experiment and the simulation. The discrepancies are, at least in part, due to the difference in energy and angular response of the dosemeters as compared with the idealised response characteristics in the MCNP calculation. In the MCNP calculation the experimental conditions were not fully simulated. The investigations also showed that the addition of boron to the phantom reduces the leakage of thermalised neutrons from the phantom, and the production of neutron induced photons in the phantom to insignificant levels. (author)

  16. Semiempirical formulas for single-particle energies of neutrons and protons

    International Nuclear Information System (INIS)

    Lodhi, M.A.K.; Waak, B.T.

    1978-01-01

    The stepwise multiple linear regression technique has been used to analyze the single-particle energies of neutrons and protons in nuclei along the line of beta stability. Their regular and systematic trends lead to semiempirical model-independent formulas for single-particle energies of neutrons and protons in the bound nuclei as functions of nuclear parameters A and Z for given states specified by nl/sub j/. These formulas are almost as convenient as the harmonic oscillator energy formulas to use. The single-particle energies computed from these formulas have been compared with the experimental data and are found in reasonable agreement

  17. Study of a spherical gaseous detector for research of rare events at low energy threshold

    International Nuclear Information System (INIS)

    Dastgheibi-Fard, Ali

    2014-01-01

    The Spherical gaseous detector (or Spherical Proportional Counter, SPC) is a novel type of a particle detector, with a broad range of applications. Its main features include a very low energy threshold which is independent of the volume (due to its very low capacitance), a good energy resolution, robustness and a single detection readout channel. SEDINE, a low background detector installed at the underground site of Laboratoire Souterrain de Modane is currently being operated and aims at measuring events at a very low energy threshold, around 40 eV. The sensitivity for the rare events detection at low energy is correlated to the detector background and to the decreasing the level of energy threshold, which was the main point of this thesis. A major effort has been devoted to the operating of the experimental detector. Several detection parameters were optimized: the electric field homogeneity in the sphere, keeping clear of sparks, the electronic noise level and the leak rate of the detector. The detector is optimized for operation with a high pressure stable gain. The modification of the shield, cleanings of the detector and the addition of an anti-Radon tent have significantly reduced the background of SEDINE. Progress has increased the sensitivity of the detector at low energy up to a value comparable to the results other underground research experiences for the low mass WIMPs. We will present the results with a measured background in the region of keV, which has allowed us to show a competitive figure of exclusion for the production of light dark matter. (author) [fr

  18. Thermal neutron group constants in monoatomic-gas approximation

    Energy Technology Data Exchange (ETDEWEB)

    Matausek, M V; Bosevski, T [Institute of nuclear sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

    1965-12-15

    To solve the problem of space-energy neutron distribution in an elementary reactor cell, a combination of the multigroup procedure and the P{sub 3} approximation of the spherical harmonics method was chosen. The calculation was divided into two independent parts: the first part was to provide multigroup constants which serve as input data for the second part - the determination of the slow neutron spectra. In the present report only the first part of the problem will be discussed. The velocity dependence of cross-sections and scattering function in thermal range was interpreted by the monoatomic-gas model. A digital computer program was developed for the evaluation of the group values for these quantities (author00.

  19. Calculated microdose spectra for intermediate energy neutrons (1 to 100 keV)

    International Nuclear Information System (INIS)

    Al-Affan, I.A.M.; Watt, D.E.

    1983-01-01

    Basic formulae for calculation of energy deposition events due to insiders, starters, stoppers and crossers, using the continuous slowing down approximation have been modified to allow for the enhanced energy deposition in spherical volumes due to elastic scattering interactions which reduce the penetration depth of the charged particle recoils. Energy deposition spectra have been obtained for energies of 1, 10, 50, 100 keV in 0.2 μm and 1 μm tissue-equivalent spheres. From these, frequency and dose distributions in lineal energy and in specific energy density have been calculated. Also calculated for different neutron energies are values of zeta, the energy average of event size, as a function of the diameter of the sensitive site. The structure of the energy event distributions can be interpreted in terms of the basic physics. The effect of the modifications to the basic formulae is to increase the number of energy deposition events due to insiders and to decrease the number of starters, stoppers and crossers. The degree of the effect increases with decreasing neutron energy, increasing sphere size, and the change is most significant for low energy deposition events. (author)

  20. Calculated microdose spectra for intermediate energy neutrons (1 to 100 keV)

    Energy Technology Data Exchange (ETDEWEB)

    Al-Affan, I.A.M.; Watt, D.E. (Dundee Univ. (UK). Dept. of Medical Biophysics); Colautti, P.; Talpo, G. (Laboratori Nazionali dell' Infn, 35020, Legnaro (Padova) (Italy))

    1983-01-01

    Basic formulae for calculation of energy deposition events due to insiders, starters, stoppers and crossers, using the continuous slowing down approximation have been modified to allow for the enhanced energy deposition in spherical volumes due to elastic scattering interactions which reduce the penetration depth of the charged particle recoils. Energy deposition spectra have been obtained for energies of 1, 10, 50, 100 keV in 0.2 ..mu..m and 1 ..mu..m tissue-equivalent spheres. From these, frequency and dose distributions in lineal energy and in specific energy density have been calculated. Also calculated for different neutron energies are values of zeta, the energy average of event size, as a function of the diameter of the sensitive site. The structure of the energy event distributions can be interpreted in terms of the basic physics. The effect of the modifications to the basic formulae is to increase the number of energy deposition events due to insiders and to decrease the number of starters, stoppers and crossers. The degree of the effect increases with decreasing neutron energy, increasing sphere size, and the change is most significant for low energy deposition events.

  1. Nuclei in a neutron star

    International Nuclear Information System (INIS)

    Oyamatsu, K.; Yamada, M.

    1994-01-01

    We report on the recent progress in understanding the matter in the crust of a neutron star. For nuclides in the outer crust, recently measured masses of neutron-rich nuclei enable us to determine more accurately the stable nuclide as a function of the matter density. In the inner crust, the compressible liquid-drop model predicts successive change of the nuclear shape, from sphere to cylinder, slab, cylindrical hole and spherical hole at densities just before the transition to uniform matter. In order to go beyond the liquiddrop model, we performed the Thomas-Fermi calculation paying special attention to the surface diffuseness, and have recently calculated the shell energies of the non-spherical nuclei. We have found from these studies that all these non-spherical nuclei exist stably in the above order even if we include the surface diffuseness and shell energies. (author)

  2. Albedo analytical method for multi-scattered neutron flux calculation in cavity

    International Nuclear Information System (INIS)

    Shin, Kazuo; Selvi, S.; Hyodo, Tomonori

    1986-01-01

    A simple formula which describes multi-scattered neutron flux in a spherical cavity was derived based on the albedo concept. The formura treats a neutron source which has an arbitrary energy-angle distribution and is placed at any point in the cavity. The derived formula was applied to the estimation of neutron fluxes in two cavities, i.e. a spherical concrete cell with a 14-MeV neutron source at the center and the ''YAYOI'' reactor cavity with a pencil beam of reactor neutrons. The results of the analytical formula agreed very well with the reference data in the both problems. It was concluded that the formula is applicable to estimate the neutron fluxes in a spherical cell except for special cases that tangential source neutrons are incident to the cavity wall. (author)

  3. Comparative measurements of independent yields of 239Pu fission fragments induced by thermal and resonance neutrons

    International Nuclear Information System (INIS)

    Gundorin, N.A.; Kopach, Y.N.; Telezhnikov, S.A.

    1994-01-01

    The independent yields of 239 Pu fission fragments by means of gamma-spectroscopy method were measured for light and heavy groups on the IBR-30 reactor in Dubna. Comparative analysis of experimental data for fission induced by thermal and resonance neutrons was performed. The possibilities to increase the measurement's precision consist of the employment of a HPGe detector with high efficiency and its open-quotes activeclose quotes shielding in the gamma spectrometer, as well as a high speed electronics system. In this way the number of identified fragments will be increased and independent yields will be measured to a precision of 1-3%. Measurements at the source with shorter neutron pulse duration to increase neutron energy resolution will be possible after the reconstruction of a modern neutron source in Dubna in accordance with the IREN project

  4. A neutronic assessment of the new Spherical Cermets Fuel concept for the BWR-PB reactor

    International Nuclear Information System (INIS)

    Benchrif, A.; Chetaine, A.; Amsil, H.; Bounakhla, M.

    2010-01-01

    The tri-structural-isotopic (TRISO) fuel directly cooled by boiling light water is used in the boiling water reactor with pebble-bed coated particles (BWR-PB). At the lower coolant temperature, the TRISO fuel particles demonstrate an unacceptable irradiation swelling in the silicon carbide coating layer during a fuel cycle. So, the objectives of this paper, on the one hand is to evaluate some neutronic parameters of a new fuel concept, Spherical Cermets Fuel (SCF), for a BWR-PB reactor. On the other hand, to assess the fact of SCF fuel concept on the fuel assembly lifetime and the burn-up characteristic. All the parameters as well as Infinite Multiplication Factor, Spectrum Index, Instantaneous Conversion Ratio and Neutron Energy Spectrum was calculated then compared for the TRISO and the SCF fuel concept. It can be seen from the assessment of fuel assembly burn-up characteristics that the normalised neutron spectra of all the assembly's parts pointed out a thermal spectrum for the SCF fuel assembly's parts than the TRISO one. The SCF fuel element increase the assembly life time about 6.1 EFPY corresponding 8000 MWd/t. So, the fuel assembly can be operated for a reasonably long period without outside refuelling. The difference in the assembly lifetime might leads to SCF fuel concept adopted, because the geometry and concept of TRISO fuel particles are wholly different to SCF ones. (author)

  5. Continuous energy Monte Carlo calculations for randomly distributed spherical fuels based on statistical geometry model

    Energy Technology Data Exchange (ETDEWEB)

    Murata, Isao [Osaka Univ., Suita (Japan); Mori, Takamasa; Nakagawa, Masayuki; Itakura, Hirofumi

    1996-03-01

    The method to calculate neutronics parameters of a core composed of randomly distributed spherical fuels has been developed based on a statistical geometry model with a continuous energy Monte Carlo method. This method was implemented in a general purpose Monte Carlo code MCNP, and a new code MCNP-CFP had been developed. This paper describes the model and method how to use it and the validation results. In the Monte Carlo calculation, the location of a spherical fuel is sampled probabilistically along the particle flight path from the spatial probability distribution of spherical fuels, called nearest neighbor distribution (NND). This sampling method was validated through the following two comparisons: (1) Calculations of inventory of coated fuel particles (CFPs) in a fuel compact by both track length estimator and direct evaluation method, and (2) Criticality calculations for ordered packed geometries. This method was also confined by applying to an analysis of the critical assembly experiment at VHTRC. The method established in the present study is quite unique so as to a probabilistic model of the geometry with a great number of spherical fuels distributed randomly. Realizing the speed-up by vector or parallel computations in future, it is expected to be widely used in calculation of a nuclear reactor core, especially HTGR cores. (author).

  6. Neutrons moderation theory; Theorie du ralentissement des neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Vigier, J P

    1949-07-01

    This report gives a summarized presentation of the theory of fast neutrons diffusion and moderation in a given environment as elaborated by M. Langevin, E. Fermi, R. Marshak and others. This statistical theory is based on three assumptions: there is no inelastic diffusion, the elastic diffusion has a spherical symmetry with respect to the center of gravity of the neutron-nucleus system (s-scattering), and the effects of chemical bonds and thermal agitation of nuclei are neglected. The first chapter analyzes the Boltzmann equation of moderation, its first approximate solution (age-velocity equation) and its domain of validity, the extension of the age-velocity theory (general solution) and the boundary conditions, the upper order approximation (spherical harmonics method and Laplace transformation), the asymptotic solutions, and the theory of spatial momenta. The second chapter analyzes the energy distribution of delayed neutrons (stationary and non-stationary cases). (J.S.)

  7. Spherical harmonics solutions of multi-dimensional neutron transport equation by finite Fourier transformation

    International Nuclear Information System (INIS)

    Kobayashi, Keisuke

    1977-01-01

    A method of solution of a monoenergetic neutron transport equation in P sub(L) approximation is presented for x-y and x-y-z geometries using the finite Fourier transformation. A reactor system is assumed to consist of multiregions in each of which the nuclear cross sections are spatially constant. Since the unknown functions of this method are the spherical harmonics components of the neutron angular flux at the material boundaries alone, the three- and two-dimensional equations are reduced to two- and one-dimensional equations, respectively. The present approach therefore gives fewer unknowns than in the usual series expansion method or in the finite difference method. Some numerical examples are shown for the criticality problem. (auth.)

  8. A set-up for measuring neutron cross sections and radiation multiplicity from neutron-nucleus interaction

    International Nuclear Information System (INIS)

    Georgiev, G.P.; Ermakov, V.A.; Grigor'ev, Yu.V.

    1988-01-01

    A multiplicity detector of the ''Romashka'' type has been used on the 500 m flight part of the IBR-30 pulsed reactor. The detector consists of 16 independent sections with NaJ(Tl) crystals with a total volume of 36 liters. The geometric efficiency of single-ray detection is ∼ 80%. The gamma-ray to neutron detection efficiency ratio is ≥600 for neutrons with energies below 200 keV. This detector allows one to perform neutron capture and fission cross section measurements and to study gamma-ray multiplicity and resonance selfabsorption effects in the 20 eV-200keV neutron energy range

  9. Neutron-optical effects at very cold neutrons scattering on the spherical particles of different sizes

    International Nuclear Information System (INIS)

    Grinev, V.G.; Kudinova, O.I.; Novokshonova, L.A.; Kuznetsov, S.P.; Udovenko, A.I.; Shelagin, A.V.

    2006-01-01

    Very cold neutrons (VCN) with the wavelength λ > 4.0 ran are convenient tool for investigating the super molecular structures of different nature. Using a Born approximation (BA) to the analysis of dependencies on the wavelength of the VCN scattering cross sections, it is possible to obtain information about average sizes (R) and concentrations of the scattering particles with R∼ λ. However, with an increasing the sizes of scatterers the conditions for BA applicability can be disrupted. In this work we investigated the possibilities of BA, eikonal and geometric-optical approximations for the analysis of VCN scattering on the spherical particles with R ≥ λ

  10. Evaluation of response function of moderating-type neutron detector and application to environmental neutron measurement

    International Nuclear Information System (INIS)

    Kosako, Toshiso; Nakamura, Takashi; Iwai, Satoshi; Katsuki, Shinji; Kamata, Masashi.

    1983-08-01

    The energy-dependent response function of a multi-cylinder moderating-type BF 3 counter, so-called Bonner counter, was calculated by the time-dependent multi-group Monte Carlo code, TMMCR. The calculated response function was evaluated experimentally for neutron energy below about 50 keV down to epithermal energy by the time-of-flight method combining with a large lead pile at the Nuclear Engineering Research Laboratory, University of Tokyo and also above 50 keV by using the monoenergetic neutron standard field a t the Electrotechnical Laboratory. The time delay in the polyethylene moderator of the Bonner counter due to multiple collisions with hydrogen was analyzed by the TMMCR code and used for the time-spectrum analysis of the time-of-flight measurement. The response function obtained by these two experiments showed good agreement with the calculated results. This Bonner counter having a response function evaluated from thermal to MeV energy range was used for spectrometry and dosimetry of environmental neutrons around some nuclear facilities. The neutron spectra and dose measured in the environment around a 252 Cf fission source, fast neutron source reactor and electron synchrotron were all in good agreement with the calculated results and the measured results with other neutron detectors. (author)

  11. Nuclear data evaluations of neutron and proton incidence on Zr, Nb, and W for energy up to 200 MeV

    International Nuclear Information System (INIS)

    Kunieda, Satoshi; Shigyo, Nobuhiro; Ishibashi, Kenji

    2003-01-01

    Neutron and proton nuclear data were evaluated on Zr, Nb, and W for energy up to 200 MeV. To execute optical model calculations, spherical optical potentials were developed to reproduce experimental data for many elements. The GNASH nuclear model code was used to evaluate light-particle production cross sections. For neutron emission, giant resonance correction came to be performed in the code system. (author)

  12. Dedicated supernova detection by a network of neutral current spherical TPC detectors

    International Nuclear Information System (INIS)

    Vergados, J. D.; Giomataris, Y.

    2007-01-01

    Supernova neutrinos can easily be detected by a spherical gaseous TPC detector measuring very low energy nuclear recoils. The expected rates are quite large for a neutron-rich target since the neutrino-nucleus neutral current interaction yields a coherent contribution of all neutrons. As a matter of fact, for a typical supernova at 10 kpc, about 1000 events are expected using a spherical detector of radius 4 m with Xe gas at a pressure of 10 atm. A worldwide network of several such simple, stable, and low-cost supernova detectors with a running time of a few centuries is quite feasible

  13. Spherical tokamak power plant design issues

    International Nuclear Information System (INIS)

    Hender, T.C.; Bond, A.; Edwards, J.; Karditsas, P.J.; McClements, K.G.; Mustoe, J.; Sherwood, D.V.; Voss, G.M.; Wilson, H.R.

    2000-01-01

    The very high β potential of the spherical tokamak has been demonstrated in the START experiment. Systems code studies show the cost of electricity from spherical tokamak power plants, operating at high β in second ballooning mode stable regime, is comparable with fossil fuels and fission. Outline engineering designs are presented based on two concepts for the central rod of the toroidal field (TF) circuit - a room temperature water cooled copper rod or a helium cooled cryogenic aluminium rod. For the copper rod case the TF return limbs are supported by the vacuum vessel, while for the aluminium rod the TF coils form an independent structure. In both cases thermohydraulic and stress calculations indicate the viability of the design. Two-dimensional neutronics calculations show the feasibility of tritium self-sufficiency without an inboard blanket. The spherical tokamak has unique maintenance possibilities based on lowering major component structures into a hot cell beneath the device and these are discussed

  14. The Martin Marietta Energy Systems personnel neutron dosimetry program

    International Nuclear Information System (INIS)

    McMahan, K.L.

    1991-01-01

    Martin Marietta Energy Systems, Inc. (Energy Systems), manages five sites for the US Department of Energy. Personnel dosimetry for four of the five sites is coordinated through a Centralized External Dosimetry System (CEDS). These four sites are the Oak Ridge National Laboratory (ORNL), the Oak Ridge Y-12 Plant (Y-12), the Oak Ridge K-25 Site (K-25), and the Paducah Gaseous Diffusion Plant (PGDP). The fifth Energy Systems site, Portsmouth Gaseous Diffusion Plant, has an independent personnel dosimetry program. The current CEDS personnel neutron dosimeter was first issued in January 1989, after an evaluation and characterization of the dosimeters' response in the workplaces was performed. For the workplace characterization, Energy Systems contracted with Pacific Northwest Laboratory (PNL) to perform neutron measurements at selected locations at ORNL and Y-12. K-25 and PGDP were not included because their neutron radiation fields were similar to others already planned for characterization at ORNL and Y-12. Since the initial characterization, PNL has returned to Oak Ridge twice to perform follow up measurements, and another visit is planned in the near future

  15. Coarse-mesh rebalance methods compatible with the spherical harmonic fictitious source in neutron transport calculations

    International Nuclear Information System (INIS)

    Miller, W.F. Jr.

    1975-10-01

    The coarse-mesh rebalance method, based on neutron conservation, is used in discrete ordinates neutron transport codes to accelerate convergence of the within-group scattering source. Though very powerful for this application, the method is ineffective in accelerating the iteration on the discrete-ordinates-to-spherical-harmonics fictitious sources used for ray-effect elimination. This is largely because this source makes a minimum contribution to the neutron balance equation. The traditional rebalance approach is derived in a variational framework and compared with new rebalance approaches tailored to be compatible with the fictitious source. The new approaches are compared numerically to determine their relative advantages. It is concluded that there is little incentive to use the new methods. (3 tables, 5 figures)

  16. Unique furnace system for high-energy-neutron experiments

    International Nuclear Information System (INIS)

    Panayotou, N.F.; Green, D.R.; Price, L.S.

    1982-03-01

    The low flux of high energy neutron sources requires optimum utilization of the available neutron field. A furnace system has been developed in support of the US DOE fusion materials program which meets this challenge. Specimens positioned in two temperature zones just 1 mm away from the outside surface of a neutron window in the furnace enclosure can be irradiated simultaneously at two independent, isothermal (+- 1 0 C) temperatures. The temperature difference between these closely spaced isothermal zones is controllable from 0 to 320 0 C and the maximum temperature is 400 0 C. The design of the system also provides a controlled specimen environment, rapid heating and cooling and easy access to heaters and thermocouples. This furnace system is in use at the Rotating Target Neutron Source-II of Lawrence Livermore National Laboratory

  17. Development of NRESP98 Monte Carlo codes for the calculation of neutron response functions of neutron detectors. Calculation of the response function of spherical BF{sub 3} proportional counter

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, M.; Saito, K.; Ando, H. [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1998-05-01

    The method to calculate the response function of spherical BF{sub 3} proportional counter, which is commonly used as neutron dose rate meter and neutron spectrometer with multi moderator system, is developed. As the calculation code for evaluating the response function, the existing code series NRESP, the Monte Carlo code for the calculation of response function of neutron detectors, is selected. However, the application scope of the existing NRESP is restricted, the NRESP98 is tuned as generally applicable code, with expansion of the geometrical condition, the applicable element, etc. The NRESP98 is tested with the response function of the spherical BF{sub 3} proportional counter. Including the effect of the distribution of amplification factor, the detailed evaluation of the charged particle transportation and the effect of the statistical distribution, the result of NRESP98 calculation fit the experience within {+-}10%. (author)

  18. Synovectomy by Neutron capture; Sinovectomia por captura de neutrones

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H.R.; Torres M, C. [Centro Regional de Estudios Nucleares, Universidad Autonoma de Zacatecas, C. Cipres 10, Fracc. La Penuela, 98000 Zacatecas (Mexico)

    1998-12-31

    The Synovectomy by Neutron capture has as purpose the treatment of the rheumatoid arthritis, illness which at present does not have a definitive curing. This therapy requires a neutron source for irradiating the articulation affected. The energy spectra and the intensity of these neutrons are fundamental since these neutrons induce nuclear reactions of capture with Boron-10 inside the articulation and the freely energy of these reactions is transferred at the productive tissue of synovial liquid, annihilating it. In this work it is presented the neutron spectra results obtained with moderator packings of spherical geometry which contains in its center a Pu{sup 239} Be source. The calculations were realized through Monte Carlo method. The moderators assayed were light water, heavy water base and the both combination of them. The spectra obtained, the average energy, the neutron total number by neutron emitted by source, the thermal neutron percentage and the dose equivalent allow us to suggest that the moderator packing more adequate is what has a light water thickness 0.5 cm (radius 2 cm) and 24.5 cm heavy water (radius 26.5 cm). (Author)

  19. The energy spectrum of delayed neutrons from thermal neutron induced fission of 235U and its analytical approximation

    International Nuclear Information System (INIS)

    Doroshenko, A.Yu.; Tarasko, M.Z.; Piksaikin, V.M.

    2002-01-01

    The energy spectrum of the delayed neutrons is the poorest known of all input data required in the calculation of the effective delayed neutron fractions. In addition to delayed neutron spectra based on the aggregate spectrum measurements there are two different approaches for deriving the delayed neutron energy spectra. Both of them are based on the data related to the delayed neutron spectra from individual precursors of delayed neutrons. In present work these two different data sets were compared with the help of an approximation by gamma-function. The choice of this approximation function instead of the Maxwellian or evaporation type of distribution is substantiated. (author)

  20. Spherically symmetric near-critical accretion onto neutron stars

    International Nuclear Information System (INIS)

    Miller, G.S.

    1990-01-01

    Numerical and approximate analytic solutions for time-independent, spherically symmetric, radiation pressure-dominated accretion flows are presented. For flows with luminosities at infinity, L-infinity, sufficiently close to the Eddington limit L-crit, the flow velocity profile is qualitatively different from the modified free-fall profile v(r) = (1 - L-infinity/L-crit)exp 1/2 (2GM/r)exp 1/2. Advective contributions to the comoving radiation flux decelerate the flow within a criical radius, and, in this settling region, the velocity of the flow decreases linearly with decreasing radius. 14 refs

  1. Secondary extinction in cylindrical and spherical crystals for X-ray and neutron diffraction

    International Nuclear Information System (INIS)

    Hu Huachen; Li Zhaohuan; Yang Bin; Shen Caiwan

    2001-01-01

    The distribution of the reflection power ratio for a neutron or x-ray diffracted from a cylindrical crystal immersed in an homogenous incident beam is obtained by the numerical solution of the transfer equations for the first time. The profile well reflects all the physical properties of the absorption and extinction behaviour in the crystals. A systematic investigation of the secondary extinction for cylindrical and spherical crystals was carried out based on these results

  2. Three-dimensional reconstruction of neutron, gamma-ray, and x-ray sources using spherical harmonic decomposition

    Science.gov (United States)

    Volegov, P. L.; Danly, C. R.; Fittinghoff, D.; Geppert-Kleinrath, V.; Grim, G.; Merrill, F. E.; Wilde, C. H.

    2017-11-01

    Neutron, gamma-ray, and x-ray imaging are important diagnostic tools at the National Ignition Facility (NIF) for measuring the two-dimensional (2D) size and shape of the neutron producing region, for probing the remaining ablator and measuring the extent of the DT plasmas during the stagnation phase of Inertial Confinement Fusion implosions. Due to the difficulty and expense of building these imagers, at most only a few two-dimensional projections images will be available to reconstruct the three-dimensional (3D) sources. In this paper, we present a technique that has been developed for the 3D reconstruction of neutron, gamma-ray, and x-ray sources from a minimal number of 2D projections using spherical harmonics decomposition. We present the detailed algorithms used for this characterization and the results of reconstructed sources from experimental neutron and x-ray data collected at OMEGA and NIF.

  3. Development of neutron-monitor detectors applicable for energies up to 100 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Tatsuhiko; Endo, Akira; Yamaguchi, Yasuhiro; Kim, Eunjoo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Nakamura, Takashi [Tohoku Univ., Sendai, Miyagi (Japan)

    2003-03-01

    For the purpose of monitoring of neutron doses in high energy accelerator facilities, we have been developing neutron detectors which are applicable for neutron energies up to 100 MeV. The present paper reports characteristics of a phoswitch-type neutron detector which is composed of a liquid organic scintillator and {sup 6}Li+ZnS(Ag) sheets. (author)

  4. Development of a medium energy polarized neutron facility

    International Nuclear Information System (INIS)

    Burzynski, S.; Gysin, C.; Henneck, R.; Jourdan, J.; Kohler, D.; Pickar, M.A.; Plattner, G.R.; Sick, I.; Berdoz, A.; Foroughi, F.; Nussbaum, Ch.; Stammbach, Th.

    1984-01-01

    By the end of 1983 the major construction work for the new polarized neutron source was completed. The source will provide an essentially monoenergetic beam of both polarized and unpolarized neutrons in the energy range from 20 MeV to 70 MeV. Intensities are expected to be approx. 2 x 10 5 neutrons/s.cm 2 per μA of incident proton beam. The polarization is expected to be approx. 0.2 and can be chosen to be either longitudinal or transverse. Protons from the Philips injector cyclotron are focussed onto a liquid deuterium target and produce neutrons via the 2 H(p,n)2p reaction at 0 0 . This process provides essentially monoenergetic neutrons of almost the same energy as the incoming protons. The zero production angle implies that the neutron polarization comes from the polarization of the proton beam only. This allows an easy and fast change of the neutron spin direction by selecting proton spin states in the polarized ion source (atomic beam type). (Auth.)

  5. Criticality problems for slabs and spheres in energy dependent neutron transport theory

    International Nuclear Information System (INIS)

    Victory, H.D. Jr.

    1980-01-01

    The steady-state equation for energy-dependent neutron transport in isotropically scattering slabs and spheres is formulated as an integral equation. The Perron-Frobenius-Jentzsch theory of positive operators is used to analyze criticality problems for transport in slab and spherical media consisting of core and reflector. In addition, with an adroit selection of diffusion-like solutions, this theory is used to obtain an expression relating the critical radius of a homogeneous sphere to a parameter characterizing fission production. 21 refs

  6. Thermalization of monoenergetic neutrons in a concrete room

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H.R.; Manzanares A, E.; Hernandez D, V.M.; Mercado, G.A. [UAZ, A.P. 336, 98000 Zacatecas (Mexico); Iniguez, M.P.; Martin M, A. [Universidad de Valladolid, (Spain)

    2006-07-01

    The thermalization of neutrons from monoenergetic neutron sources in a concrete room has been studied. During calibration of neutron detectors it is mandatory to make corrections due to neutron scattering produced by the room walls, therefore this factor must be known in advance. The scattered neutrons are thermalized and produce a neutron field that is directly proportional to source strength and inversely proportional to room total wall-surfaces, the proportional coefficient has been calculated for neutrons whose energy goes from 1 eV to 20 MeV. This coefficient was calculated using Monte Carlo methods for 150, 200 and 300 cm-radius spherical cavity, where monoenergetic neutrons were located at the center, along the spherical cavity radius neutron spectra were calculated at several source-to-detector distances inside the cavity. The obtained coefficient is almost three times larger than the factor normally utilized. (Author)

  7. Effects of zonal flows on correlation between energy balance and energy conservation associated with nonlinear nonviscous atmospheric dynamics in a thin rotating spherical shell

    Science.gov (United States)

    Ibragimov, Ranis N.

    2018-03-01

    The nonlinear Euler equations are used to model two-dimensional atmosphere dynamics in a thin rotating spherical shell. The energy balance is deduced on the basis of two classes of functorially independent invariant solutions associated with the model. It it shown that the energy balance is exactly the conservation law for one class of the solutions whereas the second class of invariant solutions provides and asymptotic convergence of the energy balance to the conservation law.

  8. ABAREX -- A neutron spherical optical-statistical-model code -- A user`s manual

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.B. [ed.; Lawson, R.D.

    1998-06-01

    The contemporary version of the neutron spherical optical-statistical-model code ABAREX is summarized with the objective of providing detailed operational guidance for the user. The physical concepts involved are very briefly outlined. The code is described in some detail and a number of explicit examples are given. With this document one should very quickly become fluent with the use of ABAREX. While the code has operated on a number of computing systems, this version is specifically tailored for the VAX/VMS work station and/or the IBM-compatible personal computer.

  9. High energy neutron generator

    International Nuclear Information System (INIS)

    Barjon, R.; Breynat, G.

    1987-01-01

    This patent describes a generator of fast neutrons only slightly contaminated by neutrons of energy less than 15 MeV, comprising a source of charged particles of energy equal to at least 15 MeV, a target made of lithium deuteride, and means for cooling the target. The target comprises at least two elements placed in series in the path of the charged particles and separated from each other, the thickness of each of the elements being selected as a function of the average energy of the charged particles emitted from the source and the energy of the fast neutrons to be generated such that neutrons of energy equal to at least 15 MeV are emitted in the forward direction in response to the bombardment of the target from behind by the charged particles. The target cooling means comprises means for circulating between and around the elements a gas which does not chemically react with lithium deuteride

  10. The impact of ICRP 60 recommendations on the dose equivalent in low- and high energy neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Jakes, J; Schraube, H [GSF-Forschungszentrum Neuberg, D-85758 Oberschleissheim (Germany). Inst. fuer Strahlenschutz

    1996-12-31

    The objectives of this study was to determine the impact of the increased risk factors for neutrons after ICRP 60 on the operational dose equivalent quantities at a few neutron fields selected with the respect to cover the broad variety of neutron spectra: (1) Cadarache calibration assembly, with average neutron energy around 0.6 MeV, designed to simulate realistic neutron spectra at workplaces. This assembly is basically composed of an almost spherical {sup 238}U converter irradiated by 14.6 MeV neutrons from an accelerator target, placed at its center, and a scattering chamber consisting of a cylindrical polyethylene duct and a series of additional shieldings; (2) Neutron spectra at exposed workplaces in nuclear power plants; (3) Moderated spectra of {sup 252}Cf fission source; (4) Neutron spectra behind a shielding made of the iron (the average energy 5.,89 MeV) and concrete (the average energy 46.51 MeV), respectively; (5) Cosmic rays induced neutron spectra measured on the top of the Zugspitze (2968 m) where there is the average neutron energy around 40 MeV. From the derived neutron spectra, the mean quality factors and conversion factors h after ICRP 21 and ICRP 60, respectively, were calculated. The dose equivalent conversion factors were taken for the region below 20 MeV, and the energy region above 20 MeV. The results show that the operational quantities were affected predominately in the low energy fields, where the changes are given by a factor of 1,3 for the neutron fields given above. As has been expected, the impact of the new recommendations depends on the shape of the neutron spectra. Therefore, this factor can be much higher in the fields where the intermediate energy region is dominant, which is the case of moderated and scattered spectra at some places in the nuclear power plant and around containers with the spent fuel elements. (J.K.) 9 refs.

  11. Equivalence of the spherical and deformed shell-model approach to intruder states

    International Nuclear Information System (INIS)

    Heyde, K.; Coster, C. de; Ryckebusch, J.; Waroquier, M.

    1989-01-01

    We point out that the description of intruder states, incorporating particle-hole (p-h) excitation across a closed shell in the spherical shell model or a description starting from the Nilsson model are equivalent. We furthermore indicate that the major part of the nucleon-nucleon interaction, responsible for the low excitation energy of intruder states comes as a two-body proton-neutron quadrupole interaction in the spherical shell model. In the deformed shell model, quadrupole binding energy is gained mainly through the one-body part of the potential. (orig.)

  12. Determining space-energy distribution of thermal neutrons in heterogeneous cylindrically symmetric reactor cell, Master Thesis

    International Nuclear Information System (INIS)

    Matausek, M. V.

    1966-06-01

    A combination of multigroup method and P 3 approximation of spherical harmonics method was chosen for calculating space-energy distribution of thermal neutron flux in elementary reactor cell. Application of these methods reduced solution of complicated transport equation to the problem of solving an inhomogeneous system of six ordinary firs-order differential equations. A procedure is proposed which avoids numerical solution and enables analytical solution when applying certain approximations. Based on this approach, computer codes were written for ZUSE-Z-23 computer: SIGMA code for calculating group constants for a given material; MULTI code which uses results of SIGMA code as input and calculates spatial ana energy distribution of thermal neutron flux in a reactor cell. Calculations of thermal neutron spectra for a number of reactor cells were compared to results available from literature. Agreement was satisfactory in all the cases, which proved the correctness of the applied method. Some possibilities for improving the precision and acceleration of the calculation process were found during calculation. (author)

  13. Reconciliation of Measured and TRANSP-calculated Neutron Emission Rates in the National Spherical Torus Experiment: Circa 2002-2005

    International Nuclear Information System (INIS)

    Medley, S.S.; Darrow, D.S.; Roquemore, A.L.

    2005-01-01

    A change in the response of the neutron detectors on the National Spherical Torus Experiment occurred between the 2002-2003 and 2004 experimental run periods. An analysis of this behavior by investigating the neutron diagnostic operating conditions and comparing measured and TRANSP-calculated neutron rates is presented. Also a revised procedure for cross calibration of the neutron scintillator detectors with the fission chamber detectors was implemented that delivers good agreement amongst the measured neutron rates for all neutron detectors and all run periods. For L-mode discharges, the measured and TRANSP-calculated neutron rates now match closely for all run years. For H-mode discharges over the entire 2002-2004 period, the 2FG scintillator and fission chamber measurements match each other but imply a neutron deficit of 11.5% relative to the TRANSP-calculated neutron. The results of this report impose a modification on all of the previously used calibration factors for the entire neutron detector suite over the 2002-2004 period. A tabular summary of the new calibration factors is provided including certified calibration factors for the 2005 run

  14. Simulations of the neutron energy-spectra at the Olympus Gate Environmental Monitoring Station due to historical Bevatron operations

    International Nuclear Information System (INIS)

    Donahue, R.J.; Thomas, R.H.; Zeman, G.H.

    2001-01-01

    and newer sets of conversion coefficients were applied to the calculated neutron energy spectra. It is concluded by this independent assessment that early dose equivalent estimates were conservative by at least a factor of 4. This reduction results from three factors: (1) a better understanding of the neutron energy spectrum at the laboratory site boundary (factor of ∼2); (2) revised conversion coefficients (factor of ∼2); and (3) the intrinsic conservatism of the reported dose equivalents (factor of ∼2). An investigation of the detector response to neutrons strongly suggests an additional systematic overestimation of the total neutron fluence by the routinely used environmental monitors. The influence of the ground on detector response has also been studied. Based on IAEA response functions, when calibrated with standard 239 PuBe neutron sources, 6-inch dia. spherical polyethylene moderators would have overestimated the dose equivalents in the accelerator spectra by a factor of about 1.3. It was also possible to show that at locations near the Olympus Gate Environmental Monitoring Station radiation levels at places not in direct view of the Bevatron were further reduced by a factor of about 2 because skyshine contributed about half the total dose equivalent

  15. Simulations and developments of the Low Energy Neutron detector Array LENA

    International Nuclear Information System (INIS)

    Langer, C.; Algora, A.; Couture, A.; Csatlós, M.; Gulyás, J.; Heil, M.; Krasznahorkay, A.; O'Donnell, J.M.; Plag, R.; Reifarth, R.; Stuhl, L.; Sonnabend, K.; Tornyi, T.; Tovesson, F.

    2011-01-01

    Prototypes of the Low Energy Neutron detector Array (LENA) have been tested and compared with detailed GEANT simulations. LENA will consist of plastic scintillation bars with the dimensions 1000×45×10 mm 3 . The tests have been performed with γ-ray sources and neutrons originating from the neutron-induced fission of 235 U. The simulations agreed very well with the measured response and were therefore used to simulate the response to mono-energetic neutrons with different detection thresholds. LENA will be used to detect low-energy neutrons from (p,n)-type reactions with low momentum transfer foreseen at the R 3 B and EXL setups at FAIR, Darmstadt.

  16. Neutron dose equivalent next to the target shield of a neutron therapy facility using an LET counter

    International Nuclear Information System (INIS)

    Stinchcomb, T.G.; Kuchnir, F.T.

    1981-01-01

    The use of a spherical tissue-equivalent proportional counter for measurements of the lineal energy (y) and derivations of the linear energy transfer (LET) for fast neutrons has the advantage of giving distributions of dose and dose equivalent as functions of either LET or y. A measurement next to the target shielding of the neutron therapy facility at the University of Chicago Hospitals and Clinics (UCHC) is described, and the data processing is outlined. The distributions are presented and compared to those from measurements in the neutron beam. The average quality factors are presented

  17. Neutronic design of a 22 MW MTR type nuclear research reactor

    International Nuclear Information System (INIS)

    Khamis, I.; Khattab, K.; Soleman, I.; Ghazi, N.

    2008-01-01

    The neutronic design calculations of a 22 MW MTR type nuclear research reactor are conducted in this project. This reactor type is selected by the Arab Atomic Energy Commission in a cooperated project. The design calculations are conducted in two methods: The deterministic method, solving the neutron transport and diffusion equations using the WIMSD4 and the CITATION codes, and the probabilistic method using the MCNP code. Good agreements are noticed between the results of the multiplication factor and the neutron flux distribution which prove the accuracy of our models using the two methods. (authors)

  18. Neutronic design of a 22 MW MTR type nuclear research reactor

    International Nuclear Information System (INIS)

    Khamis, I.; Khattab, K.; Soleman, I.; Ghazi, N.

    2006-12-01

    The neutronic design calculations of a 22 MW MTR type nuclear research reactor are conducted in this project. This reactor type is selected by the Arab Atomic Energy Commission in a cooperated project. The design calculations are conducted in two methods: The deterministic method, solving the neutron transport and diffusion equations using the WIMSD4 and the CITATION codes, and the probabilistic method using the MCNP code. Good agreements are noticed between the results of the multiplication factor and the neutron flux distribution which prove the accuracy of our models using the two methods. (author)

  19. Spin observables in proton-neutron scattering at intermediate energy

    International Nuclear Information System (INIS)

    Spinka, H.

    1986-05-01

    A summary of np elastic scattering spin measurements at intermediate energy is given. Preliminary results from a LAMPF experiment to measure free neutron-proton elastic scattering spin-spin correlation parameters are presented. A longitudinally polarized proton target was used. These measurements are part of a program to determine the neutron-proton amplitudes in a model independent fashion at 500, 650, and 800 MeV. Some new proton-proton total cross sections in pure helicity states (Δσ/sub L/(pp)) near 3 GeV/c are also given. 37 refs., 2 figs

  20. Determination of the total neutron cross section using average energy shift method for filtered neutron beam

    Directory of Open Access Journals (Sweden)

    О. О. Gritzay

    2016-12-01

    Full Text Available Development of the technique for determination of the total neutron cross sections from the measurements of sample transmission by filtered neutrons, scattered on hydrogen is described. One of the methods of the transmission determination TH52Cr from the measurements of 52Cr sample, using average energy shift method for filtered neutron beam is presented. Using two methods of the experimental data processing, one of which is presented in this paper (another in [1], there is presented a set of transmissions, obtained for different samples and for different measurement angles. Two methods are fundamentally different; therefore, we can consider the obtained processing results, using these methods as independent. In future, obtained set of transmissions is planned to be used for determination of the parameters E0, Гn and R/ of the resonance 52Cr at the energy of 50 keV.

  1. Mean energy polarized neutron source

    International Nuclear Information System (INIS)

    Aleshin, V.A.; Zaika, N.I.; Kolotyj, V.V.; Prokopenko, V.S.; Semenov, V.S.

    1988-01-01

    Physical bases and realization scheme of a pulsed source of polarized neutrons with the energy of up to 75 MeV are described. The source comprises polarized deuteron source, transport line, low-energy ion and axial injector to the accelerator, U-240 isochronous cyclotron, targets for polarized neutron production, accelerated deuteron transport line and flight bases. The pulsed source of fast neutrons with the energy of up to 75 MeV can provide for highly polarized neutron beams with the intensity by 2-3 orders higher than in the most perfect source of this range which allows one to perform various experiments with high efficiency and energy resolution. 9 refs.; 1 fig

  2. Neutron energy measurement for practical applications

    Science.gov (United States)

    Roshan, M. V.; Sadeghi, H.; Ghasabian, M.; Mazandarani, A.

    2018-03-01

    Industrial demand for neutrons constrains careful energy measurements. Elastic scattering of monoenergetic α -particles from neutron collision enables neutron energy measurement by calculating the amount of deviation from the position where collision takes place. The neutron numbers with specific energy is obtained by counting the number of α -particles in the corresponding location on the charged particle detector. Monte Carlo simulation and COMSOL Multiphysics5.2 are used to account for one-to-one collision of neutrons with α -particles.

  3. Spherical collapse of dark energy with an arbitrary sound speed

    International Nuclear Information System (INIS)

    Basse, Tobias; Bjælde, Ole Eggers; Wong, Yvonne Y.Y.

    2011-01-01

    We consider a generic type of dark energy fluid, characterised by a constant equation of state parameter w and sound speed c s , and investigate the impact of dark energy clustering on cosmic structure formation using the spherical collapse model. Along the way, we also discuss in detail the evolution of dark energy perturbations in the linear regime. We find that the introduction of a finite sound speed into the picture necessarily induces a scale-dependence in the dark energy clustering, which in turn affects the dynamics of the spherical collapse in a scale-dependent way. As with other, more conventional fluids, we can define a Jeans scale for the dark energy clustering, and hence a Jeans mass M J for the dark matter which feels the effect of dark energy clustering via gravitational interactions. For bound objects (halos) with masses M >> M J , the effect of dark energy clustering is maximal. For those with M J , the dark energy component is effectively homogeneous, and its role in the formation of these structures is reduced to its effects on the Hubble expansion rate. To compute quantitatively the virial density and the linearly extrapolated threshold density, we use a quasi-linear approach which is expected to be valid up to around the Jeans mass. We find an interesting dependence of these quantities on the halo mass M, given some w and c s . The dependence is the strongest for masses lying in the vicinity of M ∼ M J . Observing this M-dependence will be a tell-tale sign that dark energy is dynamic, and a great leap towards pinning down its clustering properties

  4. Transformation-based spherical cloaks designed by an implicit transformation-independent method: theory and optimization

    International Nuclear Information System (INIS)

    Novitsky, Andrey; Qiu, C-W; Zouhdi, Said

    2009-01-01

    Based on the concept of the cloak generating function, we propose an implicit transformation-independent method for the required parameters of spherical cloaks without knowing the needed coordinate transformation beforehand. A non-ideal discrete model is used to calculate and optimize the total scattering cross-sections of different profiles of the generating function. A bell-shaped quadratic spherical cloak is found to be the best candidate, which is further optimized by controlling the design parameters involved. Such improved invisibility is steady even when the model is highly discretized.

  5. Magnetic structure of the swedenborgite CaBa (Co3Fe ) O7 derived by unpolarized neutron diffraction and spherical neutron polarimetry

    Science.gov (United States)

    Qureshi, N.; Díaz, M. T. Fernández; Chapon, L. C.; Senyshyn, A.; Schweika, W.; Valldor, M.

    2018-02-01

    We present a study that combines polarized and unpolarized neutrons to derive the magnetic structure of the swedenborgite compound CaBa (Co3Fe ) O7. Integrated intensities from a standard neutron diffraction experiment and polarization matrices from spherical neutron polarimetry have been simultaneously analyzed revealing a complex order, which differs from the usual spin configurations on a kagome lattice. We find that the magnetic structure is well described by a combination of two one-dimensional representations corresponding to the magnetic superspace symmetry P 21' , and it consists of spins rotating around an axis close to the [110] direction. Due to the propagation vector q =(1/3 00 ) , this modulation has cycloidal and helicoidal character rendering this system a potential multiferroic. The resulting spin configuration can be mapped onto the classical √{3 }×√{3 } structure of a kagome lattice, and it indicates an important interplay between the kagome and the triangular layers of the crystal structure.

  6. Calculating the energy spectrum of neutrons from tritium target of the NG-150 type generator

    International Nuclear Information System (INIS)

    Bortash, A.I.; Kuznetsov, V.S.

    1987-01-01

    Calculation procedure of neutron spectra yielding from the NG-150 generator target chamber with regard to deutron moderation is suggested. Using the suggested procedure, neutron spectra for different escape angles formed in the tritium target are calculated. The spectrum of neutrons scattered in cooling water is calculated. The mean energy of neutrons escaping at the angle of 0 deg equalling 14.5 MeV is obtained

  7. Influence of atmospheric turbulence on the energy focusability of Gaussian beams with spherical aberration

    International Nuclear Information System (INIS)

    Deng, Jinping; Ji, Xiaoling

    2014-01-01

    By using the four-dimensional (4D) computer code of the time-dependent propagation of laser beams through atmospheric turbulence, the influence of atmospheric turbulence on the energy focusability of Gaussian beams with spherical aberration is studied in detail, where the mean-squared beam width, the power in the bucket (PIB), the β parameter and the energy Strehl ratio are taken as the characteristic parameters. It is shown that turbulence results in beam spreading, and the effect of spherical aberration on the beam spreading decreases due to turbulence. Gaussian beams with negative spherical aberration are more affected by turbulence than those with positive spherical aberration. For the negative spherical aberration case, the focus position moves to the source plane due to turbulence. It is mentioned that the influence of turbulence on the energy focusability defined by a certain energy (i.e. PIB = 63%) is very heavy when the negative spherical aberration is very heavy. On the other hand, the influence of turbulence on the energy focusability defined by the energy within a given bucket radius (i.e. mean-squared beam width) is heaviest when a certain negative spherical aberration coefficient is adopted. (papers)

  8. Investigation of some possible changes in Am-Be neutron source configuration in order to increase the thermal neutron flux using Monte Carlo code

    Science.gov (United States)

    Basiri, H.; Tavakoli-Anbaran, H.

    2018-01-01

    Am-Be neutrons source is based on (α, n) reaction and generates neutrons in the energy range of 0-11 MeV. Since the thermal neutrons are widely used in different fields, in this work, we investigate how to improve the source configuration in order to increase the thermal flux. These suggested changes include a spherical moderator instead of common cylindrical geometry, a reflector layer and an appropriate materials selection in order to achieve the maximum thermal flux. All calculations were done by using MCNP1 Monte Carlo code. Our final results indicated that a spherical paraffin moderator, a layer of beryllium as a reflector can efficiently increase the thermal neutron flux of Am-Be source.

  9. The TENDL neutron data library and the TEND1038 38-group neutron constant system

    International Nuclear Information System (INIS)

    Abramovich, S.N.; Gorelov, V.P.; Gorshikhin, A.A.; Grebennikov, A.N.; Il'in, V.N.; Krut'ko, N.A.; Farafontov, G.G.

    2002-01-01

    The library contains neutron data for 103 nuclei - i.e. for 38 actinide nuclei (from 232 Th to 249 Cm), 26 fission fragment nuclei and 39 nuclei in structural and technological materials. The 38-group constants were obtained from TENDL. The high-energy group boundary is 20 MeV. The energy range below 1.2 eV contains 11 groups. Temperature and resonance effects were taken into account. The delayed neutron parameters for 6 groups and the yields of 40 fission fragments were obtained (light and heavy, stable and non-stable). The fast neutron features of spherical critical assemblies were calculated using constants from TEND1038. (author)

  10. Neutron cross section libraries for analysis of fusion neutronics experiments

    International Nuclear Information System (INIS)

    Kosako, Kazuaki; Oyama, Yukio; Maekawa, Hiroshi; Nakamura, Tomoo

    1988-03-01

    We have prepared two computer code systems producing neutron cross section libraries to analyse fusion neutronics experiments. First system produces the neutron cross section library in ANISN format, i.e., the multi-group constants in group independent format. This library can be obtained by using the multi-group constant processing code system MACS-N and the ANISN format cross section compiling code CROKAS. Second system is for the continuous energy cross section library for the MCNP code. This library can be obtained by the nuclear data processing system NJOY which generates pointwise energy cross sections and the cross section compiling code MACROS for the MCNP library. In this report, we describe the production procedures for both types of the cross section libraries, and show six libraries with different conditions in ANISN format and a library for the MCNP code. (author)

  11. Effect of gas filling pressure and operation energy on ion and neutron emission in a medium energy plasma focus device

    Science.gov (United States)

    Niranjan, Ram; Rout, R. K.; Srivastava, Rohit; Kaushik, T. C.

    2018-03-01

    The effects of gas filling pressure and operation energy on deuterium ions and neutrons have been studied in a medium energy plasma focus device, MEPF-12. The deuterium gas filling pressure was varied from 1 to 10 mbar at an operation energy of 9.7 kJ. Also, the operation energy was varied from 3.9 to 9.7 kJ at a deuterium gas filling pressure of 4 mbar. Time resolved emission of deuterium ions was measured using a Faraday cup. Simultaneously, time integrated and time resolved emissions of neutrons were measured using a silver activation detector and plastic scintillator detector, respectively. Various characteristics (fluence, peak density, and most probable energy) of deuterium ions were estimated using the Faraday cup signal. The fluence was found to be nearly independent of the gas filling pressure and operation energy, but the peak density and most probable energy of deuterium ions were found to be varying. The neutron yield was observed to be varying with the gas filling pressure and operation energy. The effect of ions on neutrons emission was observed at each operation condition.

  12. Microdosimetry of intermediate energy neutrons in fast neutron fields

    International Nuclear Information System (INIS)

    Saion, E.B.; Watt, D.E.

    1988-01-01

    A coaxial double cylindrical proportional counter has been constructed for microdosimetry of intermediate energy neutrons in mixed fields. Details are given of the measured gas gain and resolution characteristics of the counter for a wide range of anode voltages. Event spectra due to intermediate neutrons in any desired energy band is achieved by an appropriate choice of thickness of the common dividing wall in the counter and by appropriate use of the coincidence, anticoincidence pulse counting arrangements. Calculated estimates indicate that the dose contribution by fast neutrons to the energy deposition events in the intermediate neutron range may be as large as 25%. Empirical procedures being investigated aim to determine the necessary corrections to be applied to the microdose distributions, with a precision of 10%. (author)

  13. The solution of the multigroup neutron transport equation using spherical harmonics

    International Nuclear Information System (INIS)

    Fletcher, K.

    1981-01-01

    A solution of the multi-group neutron transport equation in up to three space dimensions is presented. The flux is expanded in a series of unnormalised spherical harmonics. Using the various recurrence formulae a linked set of first order differential equations is obtained for the moments psisup(g)sub(lm)(r), γsup(g)sub(lm)(r). Terms with odd l are eliminated resulting in a second order system which is solved by two methods. The first is a finite difference formulation using an iterative procedure, secondly, in XYZ and XY geometry a finite element solution is given. Results for a test problem using both methods are exhibited and compared. (orig./RW) [de

  14. Logic Estimation of the Optimum Source Neutron Energy for BNCT of Brain Tumors

    International Nuclear Information System (INIS)

    Dorrah, M.A.; Gaber, F.A.; Abd Elwahab, M.A.; Kotb, M.A.; Mohammed, M.M.

    2012-01-01

    BNCT is very complicated technique; primarily due to the complexity of element composition of the brain. Moreover; numerous components contributes to the over all radiation dose both to normal brain and to tumor. Simple algebraic summation cannot be applied to these dose components, since each component should at first be weighed by its relative biological effectiveness (RBE) value. Unfortunately, there is no worldwide agreement on these RBE values. For that reason, the parameters required for accurate planning of BNCT of brain tumors located at different depths in brain remained obscure. The most important of these parameters is; the source neutron energy. Thermal neutrons were formerly employed for BNCT, but they failed to prove therapeutic efficacy. Later on; epithermal neutrons were suggested proposing that they would be enough thermalized while transporting in the brain tissues. However; debate aroused regarding the source neutrons energy appropriate for treating brain tumors located at different depths in brain. Again, the insufficient knowledge regarding the RBE values of the different dose components was a major obstacle. A new concept was adopted for estimating the optimum source neutrons energy appropriate for different circumstances of BNCT. Four postulations on the optimum source neutrons energy were worked out, almost entirely independent of the RBE values of the different dose components. Four corresponding condition on the optimum source neutrons energy were deduced. An energy escalation study was carried out investigating 65 different source neutron energies, between 0.01 eV and 13.2 MeV. MCNP4B Monte C arlo neutron transport code was utilized to study the behavior of neutrons in the brain. The deduced four conditions were applied to the results of the 65 steps of the neutron energy escalation study. A source neutron energy range of few electron volts (eV) to about 30 keV was estimated to be the most appropriate for BNCT of brain tumors located at

  15. Influence of media size on energy distribution of pulsed thermal neutrons

    International Nuclear Information System (INIS)

    Dabrowska, J.

    2007-01-01

    The work is devoted to the investigation of the diffusion cooling phenomenon of pulsed thermalized neutron fields in bounded media. It is aimed at the examination of the validity of the neutron temperature model that involves the assumption that an asymptotic energy distribution of neutrons in bounded media can be described by the Maxwell distribution but with a shifted temperature, lower than a temperature of medium. The research carried out entirely by means of Monte Carlo simulation of the neutron transport was preceded by a measurement of the time decay constants obtained in all variants of Monte Carlo simulations of the experiment and the measured one was stated. The form of asymptotic energy distribution of neutrons and its dependence on the size of medium was investigated in three kinds of materials of different thermal neutron transport properties: energy independent scatterer with negligible absorption (silica), energy dependent scatterer with 1/v absorption (borated silica) and energy dependent scatterer with 1/v absorption (water). As it was expected, in the case of large media, which can be treated as infinite, neutrons attained the Maxwell energy distribution at the temperature of the medium. For all materials under investigation the average and the most probable values of the energy distribution steadily decreased with decreasing geometric dimensions of the media. At the same time a growing distortion from the pure Maxwellian energy distribution was observed, which means that the concept of the neutron temperature fails in the case of small media. Although the spectra under investigation in general did not have the Maxwellian shape, the most probable velocity in a neutron density distribution decreased linearly with the increasing geometric buckling of the medium. This dependence manifested a stronger cooling than the one predicted by a certain approximate formula. The neutron spectrum in a small medium of pure silica was cooler than the spectrum in

  16. MONTE CARLO CALCULATION OF THE ENERGY RESPONSE OF THE NARF HURST-TYPE FAST- NEUTRON DOSIMETER

    Energy Technology Data Exchange (ETDEWEB)

    De Vries, T. W.

    1963-06-15

    The response function for the fast-neutron dosimeter was calculated by the Monte Carlo technique (Code K-52) and compared with a calculation based on the Bragg-Gray principle. The energy deposition spectra so obtained show that the response spectra become softer with increased incident neutron energy ahove 3 Mev. The K-52 calculated total res nu onse is more nearly constant with energy than the BraggGray response. The former increases 70 percent from 1 Mev to 14 Mev while the latter increases 135 percent over this energy range. (auth)

  17. Some improved methods in neutron transport theory

    Energy Technology Data Exchange (ETDEWEB)

    Pop-Jordanov, J; Stefanovic, D; Kocic, A; Matausek, M; Bosevski, T [Boris Kidric Institute of Nuclear Sciences Vinca, Beograd (Yugoslavia)

    1973-07-01

    The methods described in this paper are: analytical approach to neutron spectra in case of energy dependent anisotropy of elastic scattering; Monte Carlo estimations of neutron absorption reaction rate during slowing down process; spherical harmonics treatment of space-angle-lethargy dependent slowing down transport equation; integral transport theory based on point-wise representation of variables.

  18. Simulation of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation

    International Nuclear Information System (INIS)

    Kluson, J.; Jansky, B.

    2009-01-01

    Reference mixed neutron-gamma fields are used for test and calibration of dosimetric and spectrometric systems, intercomparison measurements, and benchmark tests and represent experimental base for reactor studies. Set of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation was build in the NRI Rez. Extended sets of measurements and simulation calculations were done to describe the reference mixed field dosimetry and spectral characteristics with best achievable precision. The Monte Carlo technique was used for different experimental setups models description, comparison and verification and field characteristics simulation. Effects (hardly distinguishable experimentally) were also studied ( contributions from individual parts of experimental setup, field individual components and next effects as shadow shield cones transparency, etc.). Some results and main conclusions of these studies and calculations are presented and discussed. (authors)

  19. Simulation of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation

    International Nuclear Information System (INIS)

    Kluson, J.; Jansky, B.

    2008-01-01

    Reference mixed neutron-gamma fields are used for test and calibration of dosimetric and spectrometric systems, intercomparison measurements, and benchmark tests and represent experimental base for reactor studies. Set of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation was build in the NRI Rez. Extended sets of measurements and simulation calculations were done to describe the reference mixed field dosimetry and spectral characteristics with best achievable precision. The Monte Carlo technique was used for different experimental setups models description, comparison and verification and field characteristics simulation. Effects (hardly distinguishable experimentally) were also studied ( contributions from individual parts of experimental setup, field individual components and next effects as shadow shield cones transparency, etc.). Some results and main conclusions of these studies and calculations are presented and discussed. (authors)

  20. Synovectomy by Neutron capture

    International Nuclear Information System (INIS)

    Vega C, H.R.; Torres M, C.

    1998-01-01

    The Synovectomy by Neutron capture has as purpose the treatment of the rheumatoid arthritis, illness which at present does not have a definitive curing. This therapy requires a neutron source for irradiating the articulation affected. The energy spectra and the intensity of these neutrons are fundamental since these neutrons induce nuclear reactions of capture with Boron-10 inside the articulation and the freely energy of these reactions is transferred at the productive tissue of synovial liquid, annihilating it. In this work it is presented the neutron spectra results obtained with moderator packings of spherical geometry which contains in its center a Pu 239 Be source. The calculations were realized through Monte Carlo method. The moderators assayed were light water, heavy water base and the both combination of them. The spectra obtained, the average energy, the neutron total number by neutron emitted by source, the thermal neutron percentage and the dose equivalent allow us to suggest that the moderator packing more adequate is what has a light water thickness 0.5 cm (radius 2 cm) and 24.5 cm heavy water (radius 26.5 cm). (Author)

  1. Effect of neutron irradiation on p-type silicon

    International Nuclear Information System (INIS)

    Sopko, B.

    1973-01-01

    The possibilities are discussed of silicon isotope reactions with neutrons of all energies. In the reactions, 30 Si is converted to a stable phosphorus isotope forming n-type impurities in silicon. The above reactions proceed as a result of thermal neutron irradiation. An experiment is reported involving irradiation of two p-type silicon single crystals having a specific resistance of 2000 ohm.cm and 5000 to 20 000 ohm.cm, respectively, which changed as a result of irradiation into n-type silicon with a given specific resistance. The specific resistance may be pre-calculated from the concentration of impurities and the time of irradiation. The effects of irradiation on other silicon parameters and thus on the suitability of silicon for the manufacture of semiconductor elements are discussed. (J.K.)

  2. Future possibilities with intermediate-energy neutron beams

    International Nuclear Information System (INIS)

    Brady, F.P.

    1987-01-01

    Future possibilities for using neutrons of intermediate energies (50 - 200 MeV) as a probe of the nucleus are discussed. Some of the recent thinking concerning a systematic approach for studying elastic and inelastic scattering of electrons and hadrons and the important role of medium- and intermediate-energy neutrons in such a programme is reviewed. The advantages of neutrons in this energy range over neutrons with lower energies and over intermediate-energy pions for determining nuclear-transition and ground state densities, and for distinguishing proton from neutron density (isovector sensitivity), are noted. The important role of (n,p) charge exchange reactions in nuclear excitation studies is also reviewed. Experimental methods for utilizing neutrons as probes in elastic, inelastic, and charge exchange studies at these energies are discussed

  3. Neutronic calculations of AFPR-100 reactor based on Spherical Cermet Fuel particles

    International Nuclear Information System (INIS)

    Benchrif, A.; Chetaine, A.; Amsil, H.

    2013-01-01

    Highlights: • AFPR-100 reactor considered as a small nuclear reactor without on-site refueling originally based on TRISO micro-fuel element. • The AFPR-100 reactor was re-designed using the new Spherical Cermet fuel element. • The adoption of the Cermet fuel instead of TRISO fuel reduces the core lifetime operation by 3.1 equivalent full power years. • We discussed the new micro-fuel element candidate for small and medium sized reactors. - Abstract: The Atoms For Peace Reactor (AFPR-100), as a 100 MW(e) without the need of on-site refueling, was originally based on UO2 TRISO fuel coated particles embedded in a carbon matrix directly cooled by light water. AFPR-100 is considered as a small nuclear reactor without open-vessel refueling which is proposed by Pacific Northwest National Laboratory (PNNL). An account of significant irradiation swelling in the silicon carbide fission product barrier coating layer of TRISO fuel element, a Spherical Cermet Fuel element has been proposed. Indeed, the new fuel concept, which was developed by PNNL, consists of changing the pyro-carbon and ceramic coatings that are incompatible with low temperature by Zirconium. The latter was chosen to avoid any potential Wigner energy effect issues in the TRISO fuel element. Actually, the purpose of this study is to assess the goal of AFPR-100 concept using the Cermet fuel; undeniably, the fuel core lifetime prediction may be extended for reasonably long period without on-site refueling. In fact, we investigated some neutronic parameters of reactor core by the calculation code SRAC95. The results suggest that the core fuel lifetime beyond 12 equivalent full power years (EFPYs) is possible. Hence, the adoption of Cermet fuel concept shows a core lifetime decrease of about 3.1 EFPY

  4. Neutron dose measurements with the GSI ball at high energy accelerators

    International Nuclear Information System (INIS)

    Fehrenbacher, G.; Gutermuth, F.; Radon, T.; Kozlova, E.

    2005-01-01

    Full text: At high energy particle accelerators the production of neutron radiation dominates radiation protection. For the radiation survey at accelerators there is a need for reliable detection systems (passive radiation monitors), which can measure the dose for a wide range of neutron energies independently on the beam pulse structure of the produced radiation. In this work a passive neutron dosemeter for the measurement of the ambient dose equivalent is presented. The dosemeter is suitable for measurements of the emerging neutron radiation at accelerators for the whole energy range up to about 10 GeV. The dosemeter consists of a polyethylene sphere, TL elements (pairs of TLD600/700) and an additional lead layer (PE/Pb) in neutron fields at high energy accelerators is investigated in this work. Results of dose measurements which were performed in realistic neutron fields at the high energy accelerator SPS at CERN (CERF facility) and in Cave A at the heavy ion synchrotron SIS at GSI are presented. The results of these measurements are compared with the expected dose values from the neutron spectra determined for the measurement positions at CERF and in Cave A (FLUKA) and with the dosemeter response derived by the calculated response functions (FLUKA) folded with the neutron spectra. The comparisons show that the additional lead layer in the PE/Pb-sphere improves significantly the response of the dosemeter. The response of the PE/Pb-sphere is 40 to 50 % higher at CERF and Cave A in comparison to the bare PE-sphere. At CERF the dose values of the PE/Pb-sphere is about 25 % lower than the expected dose value, whilst for Cave A, a rather good agreement was found (2 % deviation). (author)

  5. Average fast neutron flux in three energy ranges in the Quinta assembly irradiated by two types of beams

    Directory of Open Access Journals (Sweden)

    Strugalska-Gola Elzbieta

    2017-01-01

    Full Text Available This work was performed within the international project “Energy plus Transmutation of Radioactive Wastes” (E&T - RAW for investigations of energy production and transmutation of radioactive waste of the nuclear power industry. 89Y (Yttrium 89 samples were located in the Quinta assembly in order to measure an average high neutron flux density in three different energy ranges using deuteron and proton beams from Dubna accelerators. Our analysis showed that the neutron density flux for the neutron energy range 20.8 - 32.7 MeV is higher than for the neutron energy range 11.5 - 20.8 MeV both for protons with an energy of 0.66 GeV and deuterons with an energy of 2 GeV, while for deuteron beams of 4 and 6 GeV we did not observe this.

  6. A coincidence-type ion-electron converter detector for low-energy protons

    International Nuclear Information System (INIS)

    Benka, O.; Weinzierl, P.; Dobrozemsky, R.; Stratowa, C.

    1981-04-01

    A coincidence type ion-electron converter detector has been developed and used - together with an electrostatic energy-analyser - for precision measurements of the energy distribution of recoil protons from free-neutron decay. The most important aspect of the development was, besides keeping the background below 0,2 counts/sec in the presence of a certain radiation background, to achieve a high and energy-independent counting probability for protons with energies between 100 and 1000 eV. With an acceleration voltage of about 25 kV and Al-foils (20 to 35 ug/cmsup2) as converter, we obtained counting efficiences of 70 to 85 percent. The design and performance of the detector system, employing six foils with different sensitive areas, are described and discussed in detail. (author)

  7. Casimir energy density for spherical universes in n-dimensional spacetime

    International Nuclear Information System (INIS)

    Oezcan, Mustafa

    2006-01-01

    We consider the Casimir effect for the massless conformal scalar field in an n-dimensional, closed, static universe. We calculate the renormalized vacuum energy density using the covariant point-splitting method, the mode-sum regularization and the renormalized vacuum energy with the zeta-function regularization. We observe that all odd spacetime dimensions give us the zero renormalized vacuum energy density. For even spacetime dimensions the renormalized vacuum energy density oscillates in sign. The result agrees with three regularization techniques. The Casimir energy density for spherical universes in n-dimensional spacetime is regarded as interesting both to understand the correspondence between the sign of the effect and the dimension of manifold in topology and as a key to confirming the Casimir energy for half spherical universes (manifold with boundary) in n-dimensional spacetime

  8. Time-grated energy-selected cold neutron radiography

    International Nuclear Information System (INIS)

    McDonald, T.E. Jr.; Brun, T.O.; Claytor, T.N.; Farnum, E.H.; Greene, G.L.; Morris, C.

    1998-01-01

    A technique is under development at the Los Alamos Neutron Science Center (LANSCE), Manuel Lujan Jr. Neutron Scattering Center (Lujan Center) for producing neutron radiography using only a narrow energy range of cold neutrons. The technique, referred to as Time-Gated Energy-Selected (TGES) neutron radiography, employs the pulsed neutron source at the Lujan Center with time of flight to obtain a neutron pulse having an energy distribution that is a function of the arrival time at the imager. The radiograph is formed on a short persistence scintillator and a gated, intensified, cooled CCD camera is employed to record the images, which are produced at the specific neutron energy range determined by the camera gate. The technique has been used to achieve a degree of material discrimination in radiographic images. For some materials, such as beryllium and carbon, at energies above the Bragg cutoff the neutron scattering cross section is relatively high while at energies below the Bragg cutoff the scattering cross section drops significantly. This difference in scattering characteristics can be recorded in the TGES radiography and, because the Bragg cutoff occurs at different energy levels for various materials, the approach can be used to differentiate among these materials. This paper outlines the TGES radiography technique and shows an example of radiography using the approach

  9. Method and apparatus for epithermal neutron decay logging

    International Nuclear Information System (INIS)

    Nelligan, W.B.

    1998-01-01

    The nature of hydrogenous fluids filling the pore spaces in formations surrounding a well bore are determined by irradiating the formations with bursts of high energy neutrons and using the ratio of time-dependent parameters related to the decay of epithermal neutron populations above two different energy levels to provide values indicative of the kind of fluid present, independent of porosity. The measurement above the higher of these energy levels, appr. 0.4eV, indicates the existence of hydrogenous fluid, water and hydrocarbons in the formations. The lower threshold measurement, above appr. 0.15eV, is indicative of the structure of the molecule in which the hydrogen molecule is bound and of the porosity. A pulsed neutron generator in a sonde irradiates the formations with 14meV neutrons and a pair of detectors, one shielded by cadmium, to establish the 0.4eV threshold energy level and the other, shielded by gadolinium, to establish the 0.15eV threshold energy level. Time related parameters of the count rate information, e.g. the decay constants, provided by each detector are derived. The ratio of the respective parameters is used to identify the type of fluid in the information, independent of porosity. The method and apparatus can determine water saturation, i.e. percentage of water in the formation fluid and can identify specific types of hydrocarbons under 100% hydrocarbon saturation conditions. 8 figs

  10. Neutron Beam Filters

    International Nuclear Information System (INIS)

    Adib, M.

    2011-01-01

    The purpose of filters is to transmit neutrons with selected energy, while remove unwanted ones from the incident neutron beam. This reduces the background, and the number of spurious. The types of commonly used now-a-day neutron filters and their properties are discussed in the present work. There are three major types of neutron filters. The first type is filter of selective thermal neutron. It transmits the main reflected neutrons from a crystal monochromate, while reject the higher order contaminations accompanying the main one. Beams coming from the moderator always contain unwanted radiation like fast neutrons and gamma-rays which contribute to experimental background and to the biological hazard potential. Such filter type is called filter of whole thermal neutron spectrum. The third filter type is it transmits neutrons with energies in the resonance energy range (En . 1 KeV). The main idea of such neutron filter technique is the use of large quantities of a certain material which have the deep interference minima in its total neutron cross-section. By transmitting reactor neutrons through bulk layer of such material, one can obtain the quasimonochromatic neutron lines instead of white reactor spectrum.

  11. Recent Progress on Spherical Torus Research

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Masayuki [PPPL; Kaita, Robert [PPPL

    2014-01-01

    The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio (A = R0/a) reduced to A ~ 1.5, well below the normal tokamak operating range of A ≥ 2.5. As the aspect ratio is reduced, the ideal tokamak beta β (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as β ~ 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural elongation κ, which makes its plasma shape appear spherical, the ST configuration can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to its longer term goal of attractive fusion energy power source. Since the start of the two megaampere class ST facilities in 2000, National Spherical Torus Experiment (NSTX) in the US and Mega Ampere Spherical Tokamak (MAST) in UK, active ST research has been conducted worldwide. More than sixteen ST research facilities operating during this period have achieved remarkable advances in all of fusion science areas, involving fundamental fusion energy science as well as innovation. These results suggest exciting future prospects for ST research both near term and longer term. The present paper reviews the scientific progress made by the worldwide ST research community during this new mega-ampere-ST era.

  12. Determination of space-energy distribution of resonance neutrons in reactor lattice cell and calculation of resonance integrals

    International Nuclear Information System (INIS)

    Zmijarevic, I.

    1980-01-01

    Space-energy distribution of resonance neutrons in reactor lattice cell was determined by solving the Boltzmann equation by spherical harmonics method applying P-3 approximation. Computer code SPLET used for these calculations is described. Resonance absorption and calculation of resonance integrals are described as well. Effective resonance integral values for U-238 resonance at 6.7 Ev are calculated for heavy water reactor cell with metal, oxide and carbide fuel elements

  13. Spectral distribution measurements of neutrons in paraffin borax mixtures

    International Nuclear Information System (INIS)

    El-Khatib, A.M.; Gaber, M.; Abou El-Khier, M.A.

    1987-01-01

    Neutron fluxes from a compact D-T neutron source has been measured in paraffin-borax mixtures by using activation foil detectors with successive threshold energies. The absorbed doses, backscattering coefficients and build-up factors were determined as well. The contribution of thermal and intermediate neutron dose is much lower, compared to that of fast neutrons. Among the used mediums, paraffin loaded with 4% borax concentration was found to be the best absorbing medium against neutrons at near depths within the blocks, while at a depth around 12 cm the neutron absorption (or scattering) is independent on the type of the used medium. (author)

  14. Martian Neutron Energy Spectrometer (MANES)

    Science.gov (United States)

    Maurer, R. H.; Roth, D. R.; Kinnison, J. D.; Goldsten, J. O.; Fainchtein, R.; Badhwar, G.

    2000-01-01

    High energy charged particles of extragalactic, galactic, and solar origin collide with spacecraft structures and planetary atmospheres. These primaries create a number of secondary particles inside the structures or on the surfaces of planets to produce a significant radiation environment. This radiation is a threat to long term inhabitants and travelers for interplanetary missions and produces an increased risk of carcinogenesis, central nervous system (CNS) and DNA damage. Charged particles are readily detected; but, neutrons, being electrically neutral, are much more difficult to monitor. These secondary neutrons are reported to contribute 30-60% of the dose equivalent in the Shuttle and MIR station. The Martian atmosphere has an areal density of 37 g/sq cm primarily of carbon dioxide molecules. This shallow atmosphere presents fewer mean free paths to the bombarding cosmic rays and solar particles. The secondary neutrons present at the surface of Mars will have undergone fewer generations of collisions and have higher energies than at sea level on Earth. Albedo neutrons produced by collisions with the Martian surface material will also contribute to the radiation environment. The increased threat of radiation damage to humans on Mars occurs when neutrons of higher mean energy traverse the thin, dry Martian atmosphere and encounter water in the astronaut's body. Water, being hydrogeneous, efficiently moderates the high energy neutrons thereby slowing them as they penetrate deeply into the body. Consequently, greater radiation doses can be deposited in or near critical organs such as the liver or spleen than is the case on Earth. A second significant threat is the possibility of a high energy heavy ion or neutron causing a DNA double strand break in a single strike.

  15. Quasi-spherical compression of a spark-channel plasma

    International Nuclear Information System (INIS)

    Panarella, E.

    1980-01-01

    An axial spark channel in deuterium has been used as a target for implosive shock waves created with a conventional cylindrical theta-pinch device. The compression of the channel by the implosive waves raised the plasma electron temperature to approximately 120 eV for approximately 6 kJ of condenser bank energy and 1 Torr initial gas pressure. In order to improve the efficiency of compression of the channel plasma and to reduce the end losses inherent in the cylindrical configuration, the theta-pinch geometry was then converted from cylindrical into spherical. Under identical conditions of gas pressure and condenser bank energy, the electron temperature now peaked at approximately 400 eV. When the bank energy was increased to approximately 10 kJ, neutron production was observed. The total neutron output per shot ranged from 10 5 to 10 6 and increased inversely with the pinch discharge volume

  16. Evaluation of energy responses for neutron dose-equivalent meters made in Japan

    International Nuclear Information System (INIS)

    Saegusa, J.; Yoshizawa, M.; Tanimura, Y.; Yoshida, M.; Yamano, T.; Nakaoka, H.

    2004-01-01

    Energy responses of three types of Japanese neutron dose-equivalent (DE) meters were evaluated by Monte Carlo simulations and measurements. The energy responses were evaluated for thermal neutrons, monoenergetic neutrons with energies up to 15.2 MeV, and also for neutrons from such radionuclide sources as 252 Cf and 241 Am-Be. The calculated results were corroborated with the measured ones. The angular dependence of the response and the DE response were also evaluated. As a result, reliable energy responses were obtained by careful simulations of the proportional counter, moderator and absorber of the DE meters. Furthermore, the relationship between pressure of counting gas and response of the DE meter was discussed. By using the obtained responses, relations between predicted readings of the DE meters and true DE values were studied for various workplace spectra

  17. Beam neutron energy optimization for boron neutron capture therapy using monte Carlo method

    International Nuclear Information System (INIS)

    Pazirandeh, A.; Shekarian, E.

    2006-01-01

    In last two decades the optimal neutron energy for the treatment of deep seated tumors in boron neutron capture therapy in view of neutron physics and chemical compounds of boron carrier has been under thorough study. Although neutron absorption cross section of boron is high (3836b), the treatment of deep seated tumors such as glioblastoma multiform requires beam of neutrons of higher energy that can penetrate deeply into the brain and thermalized in the proximity of the tumor. Dosage from recoil proton associated with fast neutrons however poses some constraints on maximum neutron energy that can be used in the treatment. For this reason neutrons in the epithermal energy range of 10eV-10keV are generally to be the most appropriate. The simulation carried out by Monte Carlo methods using MCBNCT and MCNP4C codes along with the cross section library in 290 groups extracted from ENDF/B6 main library. The ptimal neutron energy for deep seated tumors depends on the sue and depth of tumor. Our estimated optimized energy for the tumor of 5cm wide and 1-2cm thick stands at 5cm depth is in the range of 3-5keV

  18. Cobalt, fast neutrons and physical models: Nuclear data and measurements series

    International Nuclear Information System (INIS)

    Smith, A.B.; Guenther, P.T.; Whalen, J.F.; Lawson, R.D.

    1987-07-01

    Energy-averaged neutron total cross sections of cobalt were measured from ≅0.5 to 12.0 MeV. Differential elastic- and inelastic-scattering cross sections were measured from ≅1.5 to 10.0 MeV over the scattering-angle range ≅18 0 to 160 0 , with sufficient detail to define the energy-averaged behavior. Inelastic neutron groups were observed corresponding to ''levels'' at: 1115 +- 29, 1212 +- 24, 1307 +- 24, 1503 +- 33, 1778 +- 40, 2112 +- 40, 2224 +- 35, 2423 +- 39, 2593 +- 41 and 2810 keV. The experimental results were interpreted in terms of the spherical optical-statistical and coupled-channels models. An unusually successful description of observables was achieved over a wide energy range ( 20.0 MeV) with a spherical model having energy-dependent strengths and geometries. The energy dependencies are large below ≅7.0 MeV (i.e., ≅19.0 MeV above the Fermi energy), but become smaller and similar to those reported for ''global'' potentials at higher energies. The imaginary strength is large and decreases with energy. These imaginary-potential characteristics are attributed to neutron shell closure and collective-vibrational processes. The weak-coupling model also offers an explanation of the unusual negative energy slope and relatively small radius of the imaginary potential. The spherical optical model derived from the neutron-scattering results was extrapolated to bound energies using the dispersion relationship and the method of moments. The resulting real-potential strength and radius peak at ≅-10.0 MeV, while concurrently the real diffuseness is at a minimum. The extrapolated potential is ≅8% larger than that implied by reported particle-state energies, and ≅13% smaller than indicated by hole-state energies. 68 refs., 15 figs., 1 tab

  19. Development of integrated-type dosimeter responsive to high energy neutrons (2)

    Energy Technology Data Exchange (ETDEWEB)

    Sawamura, Teruko; Murai, Ikuo; Abe, Masashi; Uoyama, Kazuya; Das, Mala [Hokkaido Univ., Sapporo, Hokkaido (Japan); Tuda, Shuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    The response of superheated drop detectors or bubble detectors (BDs) was measured for quasi-monoenergetic neutron beams in the 40-75 MeV range. The experiments were performed at the AVF cyclotron facility, TAKASAKI Ion Accelerator for Advanced Radiation Application (TIARA) of Japan Atomic Energy Research Institute (JAERI). The measured dose sensitivities showed to be lowered to about a half the nominal sensitivity. A lead-breeder introduced to extend response to the high energy region were investigated and compared with Monte Carlo calculations by MCNPX code. (author)

  20. Measurement and analysis of leakage neutron energy spectra around the Kinki University Reactor, UTR-KINKI

    CERN Document Server

    Ogawa, Y; Sagawa, H; Tsujimoto, T

    2002-01-01

    The highly sensitive cylindrical multi-moderator type neutron spectrometer was constructed for measurement of low level environmental neutrons. This neutron spectrometer was applied for the determination of leakage neutron energy spectra around the Kinki University Reactor. The analysis of the leakage neutron energy spectra was performed by MCNP Monte Carlo code. From the obtained results, the agreement between the MCNP predictions and the experimentally determined values is fairly good, which indicates the MCNP model is correctly simulating the UTR-KINKI.

  1. A portable and wide energy range semiconductor-based neutron spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Hoshor, C.B. [Department of Physics, University of Missouri, Kansas City, MO (United States); Oakes, T.M. [Nuclear Science and Engineering Institute, University of Missouri, Columbia, MO (United States); Myers, E.R.; Rogers, B.J.; Currie, J.E.; Young, S.M.; Crow, J.A.; Scott, P.R. [Department of Physics, University of Missouri, Kansas City, MO (United States); Miller, W.H. [Nuclear Science and Engineering Institute, University of Missouri, Columbia, MO (United States); Missouri University Research Reactor, Columbia, MO (United States); Bellinger, S.L. [Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS (United States); Sobering, T.J. [Electronics Design Laboratory, Kansas State University, Manhattan, KS (United States); Fronk, R.G.; Shultis, J.K.; McGregor, D.S. [Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS (United States); Caruso, A.N., E-mail: carusoan@umkc.edu [Department of Physics, University of Missouri, Kansas City, MO (United States)

    2015-12-11

    Hand-held instruments that can be used to passively detect and identify sources of neutron radiation—either bare or obscured by neutron moderating and/or absorbing material(s)—in real time are of interest in a variety of nuclear non-proliferation and health physics applications. Such an instrument must provide a means to high intrinsic detection efficiency and energy-sensitive measurements of free neutron fields, for neutrons ranging from thermal energies to the top end of the evaporation spectrum. To address and overcome the challenges inherent to the aforementioned applications, four solid-state moderating-type neutron spectrometers of varying cost, weight, and complexity have been designed, fabricated, and tested. The motivation of this work is to introduce these novel human-portable instruments by discussing the fundamental theory of their operation, investigating and analyzing the principal considerations for optimal instrument design, and evaluating the capability of each of the four fabricated spectrometers to meet the application needs.

  2. A portable and wide energy range semiconductor-based neutron spectrometer

    International Nuclear Information System (INIS)

    Hoshor, C.B.; Oakes, T.M.; Myers, E.R.; Rogers, B.J.; Currie, J.E.; Young, S.M.; Crow, J.A.; Scott, P.R.; Miller, W.H.; Bellinger, S.L.; Sobering, T.J.; Fronk, R.G.; Shultis, J.K.; McGregor, D.S.; Caruso, A.N.

    2015-01-01

    Hand-held instruments that can be used to passively detect and identify sources of neutron radiation—either bare or obscured by neutron moderating and/or absorbing material(s)—in real time are of interest in a variety of nuclear non-proliferation and health physics applications. Such an instrument must provide a means to high intrinsic detection efficiency and energy-sensitive measurements of free neutron fields, for neutrons ranging from thermal energies to the top end of the evaporation spectrum. To address and overcome the challenges inherent to the aforementioned applications, four solid-state moderating-type neutron spectrometers of varying cost, weight, and complexity have been designed, fabricated, and tested. The motivation of this work is to introduce these novel human-portable instruments by discussing the fundamental theory of their operation, investigating and analyzing the principal considerations for optimal instrument design, and evaluating the capability of each of the four fabricated spectrometers to meet the application needs.

  3. A Neutron Elastic Scattering Study of Chromium, Iron and Nickel in the Energy Region 1.77 to 2.76 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Holmqvist, B; Johansson, S G; Lodin, G; Wiedling, T [AB Atomenergi, Nyko eping (Sweden); Salama, M [Reactor and Neutron Physics Dept., Atomic Energy Es tablishment, Cairo (Egypt)

    1970-07-01

    Elastic neutron scattering measurements have been performed on the natural elements chromium, iron and nickel. Angular distributions were recorded in the interval 20 to 160 deg at several energies in the region 1.77 to 2.76 MeV. The experimental data were analysed in terms of the optical model, applying a spherical nuclear potential.

  4. Neutron excess generation by fusion neutron source for self-consistency of nuclear energy system

    International Nuclear Information System (INIS)

    Saito, Masaki; Artisyuk, V.; Chmelev, A.

    1999-01-01

    The present day fission energy technology faces with the problem of transmutation of dangerous radionuclides that requires neutron excess generation. Nuclear energy system based on fission reactors needs fuel breeding and, therefore, suffers from lack of neutron excess to apply large-scale transmutation option including elimination of fission products. Fusion neutron source (FNS) was proposed to improve neutron balance in the nuclear energy system. Energy associated with the performance of FNS should be small enough to keep the position of neutron excess generator, thus, leaving the role of dominant energy producers to fission reactors. The present paper deals with development of general methodology to estimate the effect of neutron excess generation by FNS on the performance of nuclear energy system as a whole. Multiplication of fusion neutrons in both non-fissionable and fissionable multipliers was considered. Based on the present methodology it was concluded that neutron self-consistency with respect to fuel breeding and transmutation of fission products can be attained with small fraction of energy associated with innovated fusion facilities. (author)

  5. Measure of the efficiency of a long counter of Hanson's type and use of this counter for the survey of the slow neutrons coming from the reactor of Chatillon; Mesure de l'efficacite d'un long compteur du type Hanson et utilisation de ce compteur a l'etude des neutrons lents sortant de la pile de Chatillon

    Energy Technology Data Exchange (ETDEWEB)

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

    1953-07-01

    A detection device of fast neutrons of efficiency almost independent of the energy of the neutrons has been achieved. It efficiency has been measured in absolute value for groups of neutrons of different energies. This device allowed to get some indications on the energy composition of the neutrons leaving from the reactor of Chatillon. (author) [French] Un dispositif de detection de neutrons rapides d'efficacite pratiquement independante de l'energie des neutrons a ete realise. Son efficacite a ete mesuree en valeur absolue pour des groupes de neutrons de diverses energies. Ce dispositif a permis obtenir quelques indications sur la composition energetique des neutrons sortant de la pile de Chatillon. (auteur)

  6. Neutrons and sustainable energy research

    International Nuclear Information System (INIS)

    Peterson, V.

    2009-01-01

    Full text: Neutron scattering is essential for the study of sustainable energy materials, including the areas of hydrogen research (such as its separation, storage, and use in fuel-cells) and energy transport (such as fuel-cell and battery materials). Researchers at the Bragg Institute address critical questions in sustainable energy research, with researchers providing a source of expertise for external collaborators, specialist analysis equipment, and acting as a point of contact for the study of sustainable energy materials using neutron scattering. Some recent examples of sustainable energy materials research using neutron scattering will be presented. These examples include the storage of energy, in the form of hydrogen through a study of its location in and interaction with new porous hydrogen storage materials [1-3] and in battery materials through in-situ studies of structure during charge-discharge cycling, and use of energy in fuel cells by studying proton diffusion through fuel cell membranes.

  7. High-Energy Neutron Backgrounds for Underground Dark Matter Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu [Syracuse Univ., NY (United States)

    2016-01-01

    Direct dark matter detection experiments usually have excellent capability to distinguish nuclear recoils, expected interactions with Weakly Interacting Massive Particle (WIMP) dark matter, and electronic recoils, so that they can efficiently reject background events such as gamma-rays and charged particles. However, both WIMPs and neutrons can induce nuclear recoils. Neutrons are then the most crucial background for direct dark matter detection. It is important to understand and account for all sources of neutron backgrounds when claiming a discovery of dark matter detection or reporting limits on the WIMP-nucleon cross section. One type of neutron background that is not well understood is the cosmogenic neutrons from muons interacting with the underground cavern rock and materials surrounding a dark matter detector. The Neutron Multiplicity Meter (NMM) is a water Cherenkov detector capable of measuring the cosmogenic neutron flux at the Soudan Underground Laboratory, which has an overburden of 2090 meters water equivalent. The NMM consists of two 2.2-tonne gadolinium-doped water tanks situated atop a 20-tonne lead target. It detects a high-energy (>~ 50 MeV) neutron via moderation and capture of the multiple secondary neutrons released when the former interacts in the lead target. The multiplicity of secondary neutrons for the high-energy neutron provides a benchmark for comparison to the current Monte Carlo predictions. Combining with the Monte Carlo simulation, the muon-induced high-energy neutron flux above 50 MeV is measured to be (1.3 ± 0.2) ~ 10-9 cm-2s-1, in reasonable agreement with the model prediction. The measured multiplicity spectrum agrees well with that of Monte Carlo simulation for multiplicity below 10, but shows an excess of approximately a factor of three over Monte Carlo prediction for multiplicities ~ 10 - 20. In an effort to reduce neutron backgrounds for the dark matter experiment SuperCDMS SNO- LAB, an active neutron veto was developed

  8. Development of precise measurement method of neutron energy for plasma temperature diagnostics in thermonuclear fusion

    International Nuclear Information System (INIS)

    Mori, Chizuo; Gotoh, Junichi; Uritani, Akira; Miyahara, Hiroshi; Ikeda, Yuichiro; Kasugai, Yoshimi; Kaneko, Junichi

    1998-01-01

    There are many types of fast neutron spectrometers for plasma temperature diagnostics, 28 Si(n,α) 25 Mg reaction giving the energy resolution of 2.2% for 14 MeV neutrons, the 12 C(n,α) 9 Be reaction giving the resolution of 2.15%. These detectors, however suffer from radiation damage, which demands to exchange the detector to a new one in every a few month depending on the usage. Recoil proton method has also been developed by using liquid scintillator or plastic scintillator, as a neutron-to-proton converter in front of a Si-detector, which is called counter telescope type, giving a resolution of 4.0%. This type of spectrometer can reduce radiation damage by placing Si-detector at outside Neutron beam. The scintillator can measure the lost energy of protons in the converter (i.e. the scintillator) and the measured energy loss can be used for improving the energy resolution. However, the energy resolution of organic scintillator itself is generally not so good. We proposed to use a proportional counter with CH 4 as counting gas and also as a neutron-proton converter, which has far better energy resolution than plastic scintillators, although the time resolution of counting in proportional counters is generally inferior to that in organic scintillation counters. The characteristics of the new spectrometer were experimentally studied and also were simulated with analytical calculation. (author)

  9. Neutron radiative capture cross section of 232Th in the energy range 0.1 to 1.2 MeV

    International Nuclear Information System (INIS)

    Jain, H.M.; Kailas, S.

    1987-01-01

    Recently reported neutron radiative capture cross section of 232 Th measurements in the energy range 0.1 to 1.2 MeV are compared with the calculations based on the statistical model Hauser-Feshbach theory using the spherical optical model transmission coefficients and simple Fermi gas level density formula. The calculations are in good agreement with the recent experimental data, reproducing both the absolute magnitude and the shape exhibited by the excitation function. The results of this comparative study can be used for improving the evaluation of the neutron radiative capture cross section of 232 Th. 16 refs., 3 tables, 4 figures. (author)

  10. Neutron radiative capture cross section of 232Th in the energy range 0.1 to 1.2 MeV

    International Nuclear Information System (INIS)

    Jain, H.M.; Kailas, S.

    1987-03-01

    Recently reported neutron radiative capture cross section of Th-232 measurements in the energy range 0.1 to 1.2 MeV are compared with the calculations based on the statistical model Hauser-Feshbach theory using the spherical optical model transmission coefficients and simple Fermi gas level density formula. The calculations are in good agreement with the recent experimental data, reproducing both the absolute magnitude and the shape exhibited by the excitation function. The results of this comparative study can be used for improving the evaluation of the neutron radiative capture cross section of Th-232. (author)

  11. Field calibration of a TLD albedo dosemeter in the high-energy neutron field of CERF

    International Nuclear Information System (INIS)

    Haninger, T.; Kleinau, P.; Haninger, S.

    2017-01-01

    The new albedo dosemeter-type AWST-TL-GD 04 has been calibrated in the CERF neutron field (CERN-EU high-energy Reference Field). This type of albedo dosemeter is based on thermoluminescent detectors (TLDs) and used by the individual monitoring service of the Helmholtz Zentrum Muenchen (AWST) since 2015 for monitoring persons, who are exposed occupationally against photon and neutron radiation. The motivation for this experiment was to gain a field specific neutron correction factor N n for workplaces at high-energy particle accelerators. N n is a dimensionless factor relative to a basic detector calibration with 137 Cs and is used to calculate the personal neutron dose in terms of H p (10) from the neutron albedo signal. The results show that the sensitivity of the albedo dosemeter for this specific neutron field is not significantly lower as for fast neutrons of a radionuclide source like 252 Cf. The neutron correction factor varies between 0.73 and 1.16 with a midrange value of 0.94. The albedo dosemeter is therefore appropriate to monitor persons, which are exposed at high-energy particle accelerators. (authors)

  12. Inertial electro-magnetostatic plasma neutron sources

    International Nuclear Information System (INIS)

    Barnes, D.C.; Nebel, R.A.; Schauer, M.M.; Pickrel, M.M.

    1997-01-01

    Two types of systems are being studied experimentally as D-T plasma neutron sources. In both concepts, spherical convergence of either electrons or ions or both is used to produce a dense central focus within which D-T fusion reactions produce 14 MeV neutrons. One concept uses nonneutral plasma confinement principles in a Penning type trap. In this approach, combined electrostatic and magnetic fields provide a vacuum potential well within which electrons are confined and focused. A small (6 mm radius) spherical machine has demonstrated a focus of 30 microm radius, with a central density of up to 35 times the Brillouin density limit of a static trap. The resulting electron plasma of up to several 10 13 cm -3 provides a multi-kV electrostatic well for confining thermonuclear ions as a neutron source. The second concept (Inertial Electrostatic Confinement, or IEC) uses a high-transparence grid to form a global well for acceleration and confinement of ions. Such a system has demonstrated steady neutron output of 2 x 10 10 s -1 . The present experiment will scale this to >10 11 s -1 . Advanced designs based on each concept have been developed recently. In these proposed approaches, a uniform-density electron sphere forms an electrostatic well for ions. Ions so trapped may be focused by spherical convergence to produce a dense core. An alternative approach produces large amplitude spherical oscillations of a confined ion cloud by a small, resonant modulation of the background electrons. In both the advanced Penning trap approach and the advanced IEC approach, the electrons are magnetically insulated from a large (up to 100 kV) applied electrostatic field. The physics of these devices is discussed, experimental design details are given, present observations are analyzed theoretically, and the performance of future advanced systems are predicted

  13. Neutron energy measurement for practical applications

    Indian Academy of Sciences (India)

    M V Roshan

    2018-02-07

    . Elastic scattering of monoenergetic α-particles from neutron collision enables neutron energy measurement by calculating the amount of deviation from the position where collision takes place. The neutron numbers with ...

  14. The description of neutron and giant resonances within the quasiparticle-phonon nuclear model

    International Nuclear Information System (INIS)

    Soloviev, V.G.

    1978-01-01

    The general assumptions of the quasiparticle-phonon model of complex nuclei are given. The choice of the model Hamiltonian as an average field and residual forces is discussed. The phonon description and quasiparticle-phonon interaction are presented. The system of basic equations and their approximate solutions are obtained. The approximation is chosen so as to obtain the most correct description of few-quasiparticle components rather than of the whole wave function. The method of strength functions is presented, which plays a decisive role in practical realization of the quasiparticle-phonon model for the description of some properties of complex nuclei. The range of applicability of the quasiparticle-phonon nuclear model is determined as few-quasiparticle components of the wave functions at low, intermediate and high excitation energies averaged in a certain energy interval. The fragmentation of single-particle states in deformed nuclei is studied within this model. The dependence of neutron strength functions on the excitation energy is investigated for the transfer reactions of the type (d,p) and (d,t). The s - ,p - , and d-wave neutron strength functions are calculated at the neutron binding energy Bsub(n). A satisfactory agreement with experiment is obtained. A correct description of the radiative strength functions in spherical nuclei is obtained. The influence of the tail of the giant dipole resonance on the E1-strength functions is studied. The energies and EΛ-strength functions for giant multipole resonances in spherical and deformed nuclei are calculated. A correct description of their widths is obtained. (author)

  15. Neutron-energy-dependent cell survival and oncogenic transformation.

    Science.gov (United States)

    Miller, R C; Marino, S A; Martin, S G; Komatsu, K; Geard, C R; Brenner, D J; Hall, E J

    1999-12-01

    Both cell lethality and neoplastic transformation were assessed for C3H10T1/2 cells exposed to neutrons with energies from 0.040 to 13.7 MeV. Monoenergetic neutrons with energies from 0.23 to 13.7 MeV and two neutron energy spectra with average energies of 0.040 and 0.070 MeV were produced with a Van de Graaff accelerator at the Radiological Research Accelerator Facility (RARAF) in the Center for Radiological Research of Columbia University. For determination of relative biological effectiveness (RBE), cells were exposed to 250 kVp X rays. With exposures to 250 kVp X rays, both cell survival and radiation-induced oncogenic transformation were curvilinear. Irradiation of cells with neutrons at all energies resulted in linear responses as a function of dose for both biological endpoints. Results indicate a complex relationship between RBEm and neutron energy. For both survival and transformation, RBEm was greatest for cells exposed to 0.35 MeV neutrons. RBEm was significantly less at energies above or below 0.35 MeV. These results are consistent with microdosimetric expectation. These results are also compatible with current assessments of neutron radiation weighting factors for radiation protection purposes. Based on calculations of dose-averaged LET, 0.35 MeV neutrons have the greatest LET and therefore would be expected to be more biologically effective than neutrons of greater or lesser energies.

  16. Finite element analysis of the neutron transport equation in spherical geometry

    International Nuclear Information System (INIS)

    Kim, Yong Ill; Kim, Jong Kyung; Suk, Soo Dong

    1992-01-01

    The Galerkin formulation of the finite element method is applied to the integral law of the first-order form of the one-group neutron transport equation in one-dimensional spherical geometry. Piecewise linear or quadratic Lagrange polynomials are utilized in the integral law for the angular flux to establish a set of linear algebraic equations. Numerical analyses are performed for the scalar flux distribution in a heterogeneous sphere as well as for the criticality problem in a uniform sphere. For the criticality problems in the uniform sphere, the results of the finite element method, with the use of continuous finite elements in space and angle, are compared with the exact solutions. In the heterogeneous problem, the scalar flux distribution obtained by using discontinuous angular and spatical finite elements is in good agreement with that from the ANISN code calculation. (Author)

  17. Neutron fluence in a 18 MeV Electron Accelerator for Therapy; Fluencia de neutrones en un Acelerador de Electrones de 18 MeV para terapia

    Energy Technology Data Exchange (ETDEWEB)

    Paredes G, L C [Instituto Nacional de Investigaciones Nucleares, Direccion de Innovacion Tecnologica, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2001-07-01

    An investigation was made on the theoretical fundamentals for the determination of the neutron fluence in a linear electron accelerator for radiotherapy applications and the limit values of leakage neutron radiation established by guidelines and standards in radiation protection for these type of accelerators. This investigation includes the following parts: a) Exhaustive bibliographical review on the topics mentioned above, in order to combine and to update the necessary basic information to facilitate the understanding of this subject; b) Analysis of the accelerator operation and identification of its main components, specially in the accelerator head; c) Study of different types of targets and its materials for the Bremsstrahlung production which is based on the electron initial energy, the thickness of the target, and its angular distribution and energy, which influences in the neutron generation by means of the photonuclear and electro disintegration reactions; d) Analysis of the neutron yield based on the target type and its thickness, the energy of electrons and photons; e) Analysis of the neutron energy spectra generated in the accelerator head, inside and outside the treatment room; f) Study of the dosimetry fundamentals for neutron and photon mixed fields, the dosimeter selection criteria and standards applied for these applications, specially the Panasonic U D-809 thermoluminescent dosemeter and C R-39 nuclear track dosimeter; g) Theoretical calculation of the neutron yield using a simplified geometric model for the accelerator head with spherical cell, which considers the target, primary collimator, flattener filter, movable collimators and the head shielding as the main components for radiation production. The cases with W and Pb shielding for closed movable collimators and an irradiation field of 20 x 20 cm{sup 2} were analyzed and, h) Experimental evaluation of the leakage neutron radiation from the patient and head planes, observing that the

  18. First results of spherical GEMs

    CERN Document Server

    Pinto, Serge Duarte; Brock, Ian; Croci, Gabriele; David, Eric; de Oliveira, Rui; Ropelewski, Leszek; van Stenis, Miranda; Taureg, Hans; Villa, Marco

    2010-01-01

    We developed a method to make GEM foils with a spherical geometry. Tests of this procedure and with the resulting spherical GEMs are presented. Together with a spherical drift electrode, a spherical conversion gap can be formed. This eliminates the parallax error for detection of x-rays, neutrons or UV photons when a gaseous converter is used. This parallax error limits the spatial resolution at wide scattering angles. Besides spherical GEMs, we have developed curved spacers to maintain accurate spacing, and a conical field cage to prevent edge distortion of the radial drift field up to the limit of the angular acceptance of the detector. With these components first tests are done in a setup with a spherical entrance window but a planar readout structure; results will be presented and discussed. A flat readout structure poses difficulties, however. Therefore we will show advanced plans to make a prototype of an entirely spherical double-GEM detector, including a spherical 2D readout structure. This detector w...

  19. Calculated intensity of high-energy neutron beams

    International Nuclear Information System (INIS)

    Mustapha, B.; Nolen, J.A.; Back, B.B.

    2004-01-01

    The flux, energy and angular distributions of high-energy neutrons produced by in-flight spallation and fission of a 400 MeV/A 238 U beam and by the break-up of a 400 MeV/A deuteron beam are calculated. In both cases very intense secondary neutron beams are produced, peaking at zero degrees, with a relatively narrow energy spread. Such secondary neutron beams can be produced with the primary beams from the proposed rare isotope accelerator driver linac. The break-up of a 400 kW deuteron beam on a liquid-lithium target can produce a neutron flux of >10 10 neutrons/cm 2 /s at a distance of 10 m from the target

  20. Monte-Carlo study on primary knock-on atom energy spectrum produced by neutron radiation

    International Nuclear Information System (INIS)

    Zhou Wei; Liu Yongkang; Deng Yongjun; Ma Jimin

    2012-01-01

    Computational method on energy distribution of primary knock-on atom (PKA) produced by neutron radiation was built in the paper. Based on the DBCN card in MCNP, reaction position, reaction type and energy transfer between neutrons and atoms were recorded. According to statistic of these data, energy and space distributions of PKAs were obtained. The method resolves preferably randomicity of random number and efficiency of random sampling computation. The results show small statistical fluctuation and well statistical. Three-dimensional figure of energy and space distribution of PKAs were obtained, which would be important to evaluate radiation capability of materials and study radiation damage by neutrons. (authors)

  1. An absolute measurement of 252Cf prompt fission neutron spectrum at low energy range

    International Nuclear Information System (INIS)

    Lajtai, A.; Dyachenko, P.P.; Kutzaeva, L.S.; Kononov, V.N.; Androsenko, P.A.; Androsenko, A.A.

    1983-01-01

    Prompt neutron energy spectrum at low energies (25 keV 252 Cf spontaneous fission has been measured with a time-of-flight technique on a 30 cm flight-path. Ionization chamber and lithium-glass were used as fission fragment and neutron detectors, respectively. Lithium glasses of NE-912 (containing 6 Li) and of NE-913 (containing 7 Li) 45 mm in diameter and 9.5 mm in thickness have been employed alternatively, for the registration of fission neutrons and gammas. For the correct determination of the multiscattering effects - the main difficulty of the low energy neutron spectrum measurements - a special geometry for the neutron detector was used. Special attention was paid also to the determination of the absolute efficiency of the neutron detector. The real response function of the spectrometer was determined by a Monte-Carlo calculation. The scattering material content of the ionization chamber containing a 252 Cf source was minimized. As a result of this measurement a prompt fission neutron spectrum of Maxwell type with a T=1.42 MeV parameter was obtained at this low energy range. We did not find any neutron excess or irregularities over the Maxwellian. (author)

  2. Free-Energy Barrier of Filling a Spherical Cavity in the Presence of Line Tension: Implication to the Energy Barrier between the Cassie and Wenzel States on a Superhydrophobic Surface with Spherical Cavities.

    Science.gov (United States)

    Iwamatsu, Masao

    2016-09-20

    The free-energy barrier of filling a spherical cavity having an inner wall of various wettabilities is studied. The morphology and free energy of a lens-shaped droplet are determined from the minimum of the free energy. The effect of line tension on the free energy is also studied. Then, the equilibrium contact angle of the droplet is determined from the generalized Young's equation. By increasing the droplet volume within the spherical cavity, the droplet morphology changes from spherical with an equilibrium contact angle of 180° to a lens with a convex meniscus, where the morphological complete drying transition occurs. By further increasing the droplet volume, the meniscus changes from convex to concave. Then, the lens-shaped droplet with concave meniscus spreads over the whole inner wall, resulting in an equilibrium contact angle of 0° to leave a spherical bubble, where the morphological complete wetting transition occurs. Finally, the whole cavity is filled with liquid. The free energy shows a barrier from complete drying to complete wetting as a function of droplet volume, which corresponds to the energy barrier between the Cassie and Wenzel states of the superhydrophobic surface with spherical cavities. The free-energy maximum occurs when the meniscus of the droplet becomes flat, and it is given by an analytic formula. The effect of line tension is expressed by the scaled line tension, and this effect is largest at the free-energy maximum. The positive line tension increases the free-energy maximum, which thus increases the stability of the Cassie superhydrophobic state, whereas the negative line tension destabilizes the superhydrophobic state.

  3. Neutron measurements at nuclear power reactors [55

    CERN Document Server

    Scherpelz, R I

    2002-01-01

    Staff from the Pacific Northwest National Laboratory (operated by Battelle Memorial Institute), have performed neutron measurements at a number of commercial nuclear power plants in the United States. Neutron radiation fields at light water reactor (LWR) power plants are typically characterized by low-energy distributions due to the presence of large amounts of scattering material such as water and concrete. These low-energy distributions make it difficult to accurately monitor personnel exposures, since most survey meters and dosimeters are calibrated to higher-energy fields such as those produced by bare or D sub 2 O-moderated sup 2 sup 5 sup 2 Cf sources. Commercial plants typically use thermoluminescent dosimeters in an albedo configuration for personnel dosimetry and survey meters based on a thermal-neutron detector inside a cylindrical or spherical moderator for dose rate assessment, so their methods of routine monitoring are highly dependent on the energy of the neutron fields. Battelle has participate...

  4. Quasi-energy of ultracold neutrons

    International Nuclear Information System (INIS)

    Frank, A.I.; Nosov, V.G.

    1992-01-01

    A solution is found to the problem of the propagation of a neutron beam transmitted through a periodically acting high-speed chopper. It is a generalization of the Moshinsky's problem of the evolution of a plane wave in the right half-space after an ideal absorber at the origin of coordinates has been instantaneously removed. The energy spectrum of transmitted neutrons is found to be discrete and corresponding to their quasi-energy. Interference of the states corresponding to different satellite lines leads to a complex spatial pattern with typical beats. A number of experiments with ultracold neutrons are suggested and discussed. 12 refs.; 1 fig

  5. Study on the neutron dosimetric characteristics of Tissue Equivalent Proportional Counter

    Energy Technology Data Exchange (ETDEWEB)

    Nunomiya, T.; Kim, E.; Kurosawa, T.; Taniguchi, S.; Nakamura, T. [Tohoku Univ., Sendai (Japan). Cyclotron and Radioisotope Center; Tsujimura, N.; Momose, T.; Shinohara, K. [Japan Nuclear Cycle Development Inst., Environment and Safety Division, Tokai Works, Tokai, Ibaraki (Japan)

    1999-03-01

    The neutron dosimetric characteristics of TEPC (Tissue Equivalent Proportional Counter) has been investigated under a cooperative study between Tohoku University and JNC since 1997. This TEPC is a spherical, large volume, single-wire proportional counter (the model LETSW-5, manufactured by Far West Technology, Inc.) and filled with a tissue equivalent gas in a spherical detector of the A-150 tissue equivalent plastic. The TEPC can measure the spectra of absorbed dose in LET and easily estimate the tissue equivalent dose to neutron. This report summarizes the dosimetric characteristics of TEPC to the monoenergetic neutrons with energy from 8 keV to 15 MeV. It is found that TEPC can estimate the ambient dose equivalent, H*(10), with an accuracy from 0.9 to 2 to the neutron above 0.25 MeV and TEPC has a good counting efficiency enough to measure neutron doses with low dose rate at the stray neutron fields. (author)

  6. Neutron response study

    International Nuclear Information System (INIS)

    Endres, G.W.R.; Fix, J.J.; Thorson, M.R.; Nichols, L.L.

    1981-01-01

    Neutron response of the albedo type dosimeter is strongly dependent on the energy of the incident neutrons as well as the moderating material on the backside of the dosimeter. This study characterizes the response of the Hanford dosimeter for a variety of neutron energies for both a water and Rando phantom (a simulated human body consisting of an actual human skeleton with plastic for body muscles and certain organs). The Hanford dosimeter response to neutrons of different energies is typical of albedo type dosimeters. An approximate two orders of magnitude difference in response is observed between neutron energies of 100 keV and 10 MeV. Methods were described to compensate for the difference in dosimeter response between a laboratory neutron spectrum and the different spectra encountered at various facilities in the field. Generally, substantial field support is necessary for accurate neutron dosimetry

  7. Moderation of neutron energy

    International Nuclear Information System (INIS)

    Marlatt, G.R.

    1986-01-01

    This patent describes a nuclear reactor system having a nuclear reactor which has a core including fuel assemblies, means for transmitting through the core a coolant, the coolant having a predetermined neutron-energy moderating property, sealed tubes in the core, each tube containing a material having a different neutron-energy moderating property than the coolant, means, when actuated, to engage at least certain of the tubes, for opening certain of the tubes to permit the coolant to replace the material in the tubes thereby to change the energy spectrum of the neutrons in the reactor, hydraulic means, connected to the opening means, for actuating the opening means to engage certain of the tubes to open the tubes. A device, external to the reactor, connected to the hydraulic means controlls the actuation of the opening means, the opening means being so set with reference to the tubes that only certain of the tubes are opened at any time as the opening means is advanced towards the tubes by the hydraulic means

  8. Study of a spherical torus based volumetric neutron source for nuclear technology testing and development

    International Nuclear Information System (INIS)

    Cheng, E.T.; Cerbone, R.J.; Sviatoslavsky, I.N.; Galambos, L.D.; Peng, Y.-K.M.

    2000-01-01

    A plasma based, deuterium and tritium (DT) fueled, volumetric 14 MeV neutron source (VNS) has been considered as a possible facility to support the development of the demonstration fusion power reactor (DEMO). It can be used to test and develop necessary fusion blanket and divertor components and provide sufficient database, particularly on the reliability of nuclear components necessary for DEMO. The VNS device can be complement to ITER by reducing the cost and risk in the development of DEMO. A low cost, scientifically attractive, and technologically feasible volumetric neutron source based on the spherical torus (ST) concept has been conceived. The ST-VNS, which has a major radius of 1.07 m, aspect ratio 1.4, and plasma elongation three, can produce a neutron wall loading from 0.5 to 5 MW m -2 at the outboard test section with a modest fusion power level from 38 to 380 MW. It can be used to test necessary nuclear technologies for fusion power reactor and develop fusion core components include divertor, first wall, and power blanket. Using staged operation leading to high neutron wall loading and optimistic availability, a neutron fluence of more than 30 MW year m -2 is obtainable within 20 years of operation. This will permit the assessments of lifetime and reliability of promising fusion core components in a reactor relevant environment. A full scale demonstration of power reactor fusion core components is also made possible because of the high neutron wall loading capability. Tritium breeding in such a full scale demonstration can be very useful to ensure the self-sufficiency of fuel cycle for a candidate power blanket concept

  9. Free neutron-proton analyzing power at medium energies

    International Nuclear Information System (INIS)

    Newsom, C.R.

    1980-01-01

    In recent years, increasing efforts have been made to measure the nucleon-nucleon polarization parameters. To date, no free neutron-proton spin correlated parameters have been published in the energy range 500 to 800 MeV. Existing analyzing power data is of low precision and in most cases was obtained by quasi-free proton scattering. As a first step in determining the neutron-proton scattering matrix, the free neutron-proton analyzing power has been measured at the Los Alamos Physics Facility as a function of energy and angle. The experiment was performed by scattering a neutron beam from a polarized proton target. The neutron beam was generated by scattering 800 MeV protons from a Beryllium target and using the neutrons produced at 0 degrees. The incident energy ranged from 300 MeV to 800 MeV. The energy spread of the neutron beam made it possible to measure the analyzing power at different energies simultaneously. Angular distributions were taken from 60 to 170 degrees in the center of mass system (c.m.)

  10. Neutron energy spectrum flux profile of Ghana's miniature neutron source reactor core

    International Nuclear Information System (INIS)

    Sogbadji, R.B.M.; Abrefah, R.G.; Ampomah-Amoako, E.; Agbemava, S.E.; Nyarko, B.J.B.

    2011-01-01

    Highlights: → The total neutron flux spectrum of the compact core of Ghana's miniature neutron source reactor was studied. → Using 20,484 energy grids, the thermal, slowing down and fast neutron energy regions were studied. - Abstract: The total neutron flux spectrum of the compact core of Ghana's miniature neutron source reactor was understudied using the Monte Carlo method. To create small energy groups, 20,484 energy grids were used for the three neutron energy regions: thermal, slowing down and fast. The moderator, the inner irradiation channels, the annulus beryllium reflector and the outer irradiation channels were the region monitored. The thermal neutrons recorded their highest flux in the inner irradiation channel with a peak flux of (1.2068 ± 0.0008) x 10 12 n/cm 2 s, followed by the outer irradiation channel with a peak flux of (7.9166 ± 0.0055) x 10 11 n/cm 2 s. The beryllium reflector recorded the lowest flux in the thermal region with a peak flux of (2.3288 ± 0.0004) x 10 11 n/cm 2 s. The peak values of the thermal energy range occurred in the energy range (1.8939-3.7880) x 10 -08 MeV. The inner channel again recorded the highest flux of (1.8745 ± 0.0306) x 10 09 n/cm 2 s at the lower energy end of the slowing down region between 8.2491 x 10 -01 MeV and 8.2680 x 10 -01 MeV, but was over taken by the moderator as the neutron energies increased to 2.0465 MeV. The outer irradiation channel recorded the lowest flux in this region. In the fast region, the core, where the moderator is found, the highest flux was recorded as expected, at a peak flux of (2.9110 ± 0.0198) x 10 08 n/cm 2 s at 6.961 MeV. The inner channel recorded the second highest while the outer channel and annulus beryllium recorded very low flux in this region. The flux values in this region reduce asymptotically to 20 MeV.

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

    International Nuclear Information System (INIS)

    Paredes G, L.C.

    2001-01-01

    An investigation was made on the theoretical fundamentals for the determination of the neutron fluence in a linear electron accelerator for radiotherapy applications and the limit values of leakage neutron radiation established by guidelines and standards in radiation protection for these type of accelerators. This investigation includes the following parts: a) Exhaustive bibliographical review on the topics mentioned above, in order to combine and to update the necessary basic information to facilitate the understanding of this subject; b) Analysis of the accelerator operation and identification of its main components, specially in the accelerator head; c) Study of different types of targets and its materials for the Bremsstrahlung production which is based on the electron initial energy, the thickness of the target, and its angular distribution and energy, which influences in the neutron generation by means of the photonuclear and electro disintegration reactions; d) Analysis of the neutron yield based on the target type and its thickness, the energy of electrons and photons; e) Analysis of the neutron energy spectra generated in the accelerator head, inside and outside the treatment room; f) Study of the dosimetry fundamentals for neutron and photon mixed fields, the dosimeter selection criteria and standards applied for these applications, specially the Panasonic U D-809 thermoluminescent dosemeter and C R-39 nuclear track dosimeter; g) Theoretical calculation of the neutron yield using a simplified geometric model for the accelerator head with spherical cell, which considers the target, primary collimator, flattener filter, movable collimators and the head shielding as the main components for radiation production. The cases with W and Pb shielding for closed movable collimators and an irradiation field of 20 x 20 cm 2 were analyzed and, h) Experimental evaluation of the leakage neutron radiation from the patient and head planes, observing that the accelerator

  12. Stored Energy and Quality Factor of Spherical Wave Functions–in Relation to Spherical Antennas With Material Cores

    DEFF Research Database (Denmark)

    Hansen, Troels V.; Kim, Oleksiy S.; Breinbjerg, Olav

    2012-01-01

    wave, the excitation coefficients for the internal and external spherical waves, the radiated power, the internal and external stored electric and magnetic energies, the difference of total electric and total magnetic energy, the cavity and radiating resonance conditions, and the quality factor. We...... investigate the variation of the internal/external and electric/magnetic stored energies with the electrical size of the antenna to study their relative significance for the quality factor....

  13. Neutron energy spectra produced by α-bombardment of light elements in thick targets

    International Nuclear Information System (INIS)

    Jacobs, G.J.H.

    1982-01-01

    The aim of the work, presented in this thesis, is to determine energy spectra of neutrons produced by α-particle bombardment of thick targets containing light elements. These spectra are required for nuclear waste management. The set-up of the neutron spectrometer is described, and its calibration discussed. Absolute efficiencies were determined at various neutron energies, using monoenergetic neutrons produced with the Van de Graaff accelerator in pulsed mode. The additional calibration of the neutron spectrometer as proton-recoil spectrometer was carried out primarily for future applications in measurements where no pulsed neutron source is available or the neutron flux density is too low. The basis for an accurate uncertainty analysis is made by the determination of the covariance matrix for the uncertainties in the efficiencies. The determination of the neutron energy spectra from time-of-flight and from proton-recoil measurements is described. A comparison of the results obtained from the two different types of measurements is made. The experimentally determined spectra were compared with spectra calculated from stopping powers and theoretically determined cross sections. These cross sections were calculated from optical model parameters and level parameters using the Hauser-Feshbach formalism. Measurements were carried out on thick targets of silicon, aluminium, magnesium, carbon, boron nitride, calcium fluoride, aluminium oxide, silicon oxide and uranium oxide at four different α-particle energies. (Auth.)

  14. Estimation of scattering contribution in the calibration of neutron devices with radionuclide sources in rooms of different sizes

    Directory of Open Access Journals (Sweden)

    Khabaz Rahim

    2015-01-01

    Full Text Available Calibrations of neutron devices used in area monitoring are often performed by radionuclide neutron sources. Device readings increase due to neutrons scattered by the surroundings and the air. The influence of said scattering effects have been investigated in this paper by performing Monte Carlo simulations for ten different radionuclide neutron sources inside several sizes of concrete wall spherical rooms (Rsp = 200 to 1500 cm. In order to obtain the parameters that relate the additional contribution from scattered neutrons, calculations using a polynomial fit model were evaluated. Obtained results show that the contribution of scattering is roughly independent of the geometric shape of the calibration room. The parameter that relates the room-return scattering has been fitted in terms of the spherical room radius, so as to reasonably accurately estimate the scattering value for each radionuclide neutron source in any geometry of the calibration room.

  15. Evaluation of energy response of neutron rem monitor applied to high-energy accelerator facilities

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-03-01

    A neutron rem monitor was newly developed for applying to the high-intensity proton accelerator facility (J-PARC) that is under construction as a joint project between the Japan Atomic Energy Research Institute and the High Energy Accelerator Research Organization. To measure the dose rate accurately for wide energy range of neutrons from thermal to high-energy region, the neutron rem monitor was fabricated by adding a lead breeder layer to a conventional neutron rem monitor. The energy response of the monitor was evaluated by using neutron transport calculations for the energy range from thermal to 150 MeV. For verifying the results, the response was measured at neutron fields for the energy range from thermal to 65 MeV. The comparisons between the energy response and dose conversion coefficients show that the newly developed neutron rem monitor has a good performance in energy response up to 150 MeV, suggesting that the present study offered prospects of a practical fabrication of the rem monitor applicable to the high intensity proton accelerator facility. (author)

  16. Response of LR-115 type II and CR-39 plastic track detectors to Am-Be and 14.1-MeV neutrons

    International Nuclear Information System (INIS)

    Bradley, D.A.; Chong, C.S.; Saat, Ahmat; Sidik, A.G.; Ghose, A.M.

    1987-01-01

    The fast-neutron response of the plastic LR-115 type II and CR-39 track detectors have been compared, using a 14.1-MeV neutron generator and a radionuclide Am-Be neutron source (effective primary neutron energy 4.5-MeV). The distribution of track diameters for a range of etching times has been evaluated, taking into account track registration efficiency and the relevant fast neutron scattering cross-sections. The efficiency of etched-track formation in LR-115 type II due to neutron irradiation is approximately double that in CR-39. The 14.1-MeV neutrons also tend to produce tracks in both materials with somewhat greater efficiency than do the lower energy neutrons from the radionuclide source, for a given etching time. (author)

  17. A non-conforming 3D spherical harmonic transport solver

    Energy Technology Data Exchange (ETDEWEB)

    Van Criekingen, S. [Commissariat a l' Energie Atomique CEA-Saclay, DEN/DM2S/SERMA/LENR Bat 470, 91191 Gif-sur-Yvette, Cedex (France)

    2006-07-01

    A new 3D transport solver for the time-independent Boltzmann transport equation has been developed. This solver is based on the second-order even-parity form of the transport equation. The angular discretization is performed through the expansion of the angular neutron flux in spherical harmonics (PN method). The novelty of this solver is the use of non-conforming finite elements for the spatial discretization. Such elements lead to a discontinuous flux approximation. This interface continuity requirement relaxation property is shared with mixed-dual formulations such as the ones based on Raviart-Thomas finite elements. Encouraging numerical results are presented. (authors)

  18. A non-conforming 3D spherical harmonic transport solver

    International Nuclear Information System (INIS)

    Van Criekingen, S.

    2006-01-01

    A new 3D transport solver for the time-independent Boltzmann transport equation has been developed. This solver is based on the second-order even-parity form of the transport equation. The angular discretization is performed through the expansion of the angular neutron flux in spherical harmonics (PN method). The novelty of this solver is the use of non-conforming finite elements for the spatial discretization. Such elements lead to a discontinuous flux approximation. This interface continuity requirement relaxation property is shared with mixed-dual formulations such as the ones based on Raviart-Thomas finite elements. Encouraging numerical results are presented. (authors)

  19. Compact fusion energy based on the spherical tokamak

    Science.gov (United States)

    Sykes, A.; Costley, A. E.; Windsor, C. G.; Asunta, O.; Brittles, G.; Buxton, P.; Chuyanov, V.; Connor, J. W.; Gryaznevich, M. P.; Huang, B.; Hugill, J.; Kukushkin, A.; Kingham, D.; Langtry, A. V.; McNamara, S.; Morgan, J. G.; Noonan, P.; Ross, J. S. H.; Shevchenko, V.; Slade, R.; Smith, G.

    2018-01-01

    Tokamak Energy Ltd, UK, is developing spherical tokamaks using high temperature superconductor magnets as a possible route to fusion power using relatively small devices. We present an overview of the development programme including details of the enabling technologies, the key modelling methods and results, and the remaining challenges on the path to compact fusion.

  20. Production of low energy gamma rays by neutron interactions with fluorine for incident neutron energies between 0.1 and 20 MeV

    International Nuclear Information System (INIS)

    Morgan, G.L.; Dickens, J.K.

    1975-06-01

    Differential cross sections for the production of low-energy gamma rays (less than 240 keV) by neutron interactions in fluorine have been measured for neutron energies between 0.1 and 20 MeV. The Oak Ridge Electron Linear Accelerator was used as the neutron source. Gamma rays were detected at 92 0 using an intrinsic germanium detector. Incident neutron energies were determined by time-of-flight techniques. Tables are presented for the production cross sections of three gamma rays having energies of 96, 110, and 197 keV. (14 figures, 3 tables) (U.S.)

  1. Transformations of solutions for equations and hierarchies of pseudo-spherical type

    CERN Document Server

    Reyes, E G

    2003-01-01

    It is known that if an equation describes non-trivial one-parameter families of pseudo-spherical surfaces, its conservation laws, (generalized, nonlocal) symmetries and Baecklund transformations can be studied by geometrical means [4, 10]. In this letter it is pointed out that there exist correspondences, or 'generalized Baecklund transformations', between arbitrary solutions (satisfying some genericity conditions) of any two single equations describing pseudo-spherical surfaces. Then, the notion of a hierarchy of equations of pseudo-spherical type is introduced, and a theorem stating that there also exist correspondences between arbitrary solutions of any two such hierarchies is presented. A full account of these results appears elsewhere [12, 13]. (letter to the editor)

  2. High energy proton simulation of 14-MeV neutron damage in Al2O3

    International Nuclear Information System (INIS)

    Muir, D.W.; Bunch, J.M.

    1975-01-01

    High-energy protons are a potentially useful tool for simulating the radiation damage produced by 14-MeV neutrons in CTR materials. A comparison is given of calculations and measurements of the relative damage effectiveness of these two types of radiation in single-crystal Al 2 O 3 . The experiments make use of the prominent absorption band at 206 nm as an index to lattice damage, on the assumption that peak absorption is proportional to the concentration of lattice vacancies. The induced absorption is measured for incident proton energies ranging from 5 to 15 MeV and for 14-MeV neutrons. Recoil-energy spectra are calculated for elastic and inelastic scattering using published angular distributions. Recoil-energy spectra also are calculated for the secondary alpha particles and 12 C nuclei produced by (p,p'α) reactions on 16 O. The recoil spectra are converted to damage-energy spectra and then integrated to yield the damage-energy cross section at each proton energy and for 14 MeV neutrons. A comparison of the calculations with experimental results suggests that damage energy, at least at high energies, is a reasonable criterion for estimating this type of radiation damage. (auth)

  3. The calculated neutron response of a sphere with the multi-counters

    International Nuclear Information System (INIS)

    Li Taosheng; Yang Lianzhen; Li Dongyu

    2004-01-01

    Based on the difference of the neutron distribution in the moderator, three position sensitive proportional counters which are perpendicular to each other are inserted into the moderator. The energy responses with six spherical moderators and six incidence directions have been calculated by MCNP4A code. The calculated results for two divided region methods in the radial of the spherical moderator have been analyzed and compared. (authors)

  4. Accelerator driven reactors, - the significance of the energy distribution of spallation neutrons on the neutron statistics

    Energy Technology Data Exchange (ETDEWEB)

    Fhager, V

    2000-01-01

    In order to make correct predictions of the second moment of statistical nuclear variables, such as the number of fissions and the number of thermalized neutrons, the dependence of the energy distribution of the source particles on their number should be considered. It has been pointed out recently that neglecting this number dependence in accelerator driven systems might result in bad estimates of the second moment, and this paper contains qualitative and quantitative estimates of the size of these efforts. We walk towards the requested results in two steps. First, models of the number dependent energy distributions of the neutrons that are ejected in the spallation reactions are constructed, both by simple assumptions and by extracting energy distributions of spallation neutrons from a high-energy particle transport code. Then, the second moment of nuclear variables in a sub-critical reactor, into which spallation neutrons are injected, is calculated. The results from second moment calculations using number dependent energy distributions for the source neutrons are compared to those where only the average energy distribution is used. Two physical models are employed to simulate the neutron transport in the reactor. One is analytical, treating only slowing down of neutrons by elastic scattering in the core material. For this model, equations are written down and solved for the second moment of thermalized neutrons that include the distribution of energy of the spallation neutrons. The other model utilizes Monte Carlo methods for tracking the source neutrons as they travel inside the reactor material. Fast and thermal fission reactions are considered, as well as neutron capture and elastic scattering, and the second moment of the number of fissions, the number of neutrons that leaked out of the system, etc. are calculated. Both models use a cylindrical core with a homogenous mixture of core material. Our results indicate that the number dependence of the energy

  5. Accelerator driven reactors, - the significance of the energy distribution of spallation neutrons on the neutron statistics

    International Nuclear Information System (INIS)

    Fhager, V.

    2000-01-01

    In order to make correct predictions of the second moment of statistical nuclear variables, such as the number of fissions and the number of thermalized neutrons, the dependence of the energy distribution of the source particles on their number should be considered. It has been pointed out recently that neglecting this number dependence in accelerator driven systems might result in bad estimates of the second moment, and this paper contains qualitative and quantitative estimates of the size of these efforts. We walk towards the requested results in two steps. First, models of the number dependent energy distributions of the neutrons that are ejected in the spallation reactions are constructed, both by simple assumptions and by extracting energy distributions of spallation neutrons from a high-energy particle transport code. Then, the second moment of nuclear variables in a sub-critical reactor, into which spallation neutrons are injected, is calculated. The results from second moment calculations using number dependent energy distributions for the source neutrons are compared to those where only the average energy distribution is used. Two physical models are employed to simulate the neutron transport in the reactor. One is analytical, treating only slowing down of neutrons by elastic scattering in the core material. For this model, equations are written down and solved for the second moment of thermalized neutrons that include the distribution of energy of the spallation neutrons. The other model utilizes Monte Carlo methods for tracking the source neutrons as they travel inside the reactor material. Fast and thermal fission reactions are considered, as well as neutron capture and elastic scattering, and the second moment of the number of fissions, the number of neutrons that leaked out of the system, etc. are calculated. Both models use a cylindrical core with a homogenous mixture of core material. Our results indicate that the number dependence of the energy

  6. The Los Alamos Intense Neutron Source

    International Nuclear Information System (INIS)

    Nebel, R.A.; Barnes, D.C.; Bollman, R.; Eden, G.; Morrison, L.; Pickrell, M.M.; Reass, W.

    1997-01-01

    The Intense Neutron Source (INS) is an Inertial Electrostatic Confinement (IEC) fusion device presently under construction at Los Alamos National Laboratory. It is designed to produce 10 11 neutrons per second steady-state using D-T fuel. Phase 1 operation of this device will be as a standard three grid IEC ion focus device. Expected performance has been predicted by scaling from a previous IEC device. Phase 2 operation of this device will utilize a new operating scheme, the Periodically Oscillating Plasma Sphere (POPS). This scheme is related to both the Spherical Reflect Diode and the Oscillating Penning Trap. With this type of operation the authors hope to improve plasma neutron production to about 10 13 neutrons/second

  7. Intermediate-energy neutron beams from reactors for NCT

    International Nuclear Information System (INIS)

    Brugger, R.M.; Less, T.J.; Passmore, G.G.

    1986-01-01

    This paper discusses ways that a beam of intermediate-energy neutrons might be extracted from a nuclear reactor. The challenge is to suppress the fast-neutron component and the gamma-ray component of the flux while leaving enough of the intermediate-energy neutrons in the beam to be able to perform neutron capture therapy in less than an hour exposure time. Moderators, filters, and reflectors are considered. 11 references, 7 figures, 3 tables

  8. Neutron total, scattering and inelastic gamma-ray cross sections of yttrium at few MeV energies

    International Nuclear Information System (INIS)

    Budtz-Joergensen, C.; Guenther, P.; Smith, A.; Whalen, J.; McMurray, W.R.; Renan, M.J.; Heerden, I.J. van

    1984-01-01

    Neutron total, scattering and (n; n', γ) cross sections of elemental yttrium ( 89 Y) were measured in the few-MeV region. The neutron total-cross-section measurements were made with broad resolutions from approx.=0.5 to 4.2 MeV in steps of < or approx.0.1 MeV. Neutron elastic- and inelastic-scattering cross sections were measured from approx.=1.5 to 4.0 MeV, at incident-neutron energy intervals of approx.=50 keV and at ten or more scattering angles distributed between 20 and 160 degrees using neutron detection. Inelastic-scattering cross sections were also determined using the (n; n', γ) reaction at incident energies from 1.6 to 3.8 MeV at intervals of 0.1 MeV. Gamma-rays and/or inelastically-scattered neutrons were observed corresponding to the excitation of levels at: 909.0+-0.5, 1,507.4+-0.3, 1,744.5+-0.3, 2,222.6+-0.5, 2,530+-0.8, 2,566.4+-1.0, 2,622.5+-1.0, 2,871.9+-1.5, 2,880.6+-2.0, 3,067.0+-2.0, 3,107.0+-2.0, 3,140.0+-2.0, 3,410.0+-2.0, 3,450.0+-2.0, 3,504.0+-1.5, 3,514.0+-2.0, 3,556.0+-2.0, 3,619.0+-3.0, 3,629.0+-3.0 and 3,715.0+-3.0 keV. The experimental results are discussed in terms of the spherical-optical-statistical, coupled-channels, and core-coupling models, and in the context of previously reported excited-level structure. (orig.)

  9. 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

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

    International Nuclear Information System (INIS)

    Brunckhorst, Elin

    2009-01-01

    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 10 B-coated magnesium chamber) and two types of thermoluminescence detectors (enriched with 6 Li and 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 with an

  11. Microscopic description of quadrupole collectivity in neutron-rich nuclei across the N = 126 shell closure

    Science.gov (United States)

    Rodríguez-Guzmán, R.; Robledo, L. M.; Sharma, M. M.

    2015-06-01

    The quadrupole collectivity in Nd, Sm, Gd, Dy, Er, Yb, Hf and W nuclei with neutron numbers 122 ≤ N ≤ 156 is studied, both at the mean field level and beyond, using the Gogny energy density functional. Besides the robustness of the N = 126 neutron shell closure, it is shown that the onset of static deformations in those isotopic chains with increasing neutron number leads to an enhanced stability and further extends the corresponding two-neutron drip lines far beyond what could be expected from spherical calculations. Independence of the mean-field predictions with respect to the particular version of the Gogny energy density functional employed is demonstrated by comparing results based on the D1S and D1M parameter sets. Correlations beyond mean field are taken into account in the framework of the angular momentum projected generator coordinate method calculation. It is shown that N = 126 remains a robust neutron magic number when dynamical effects are included. The analysis of the collective wave functions, average deformations and excitation energies indicate that, with increasing neutron number, the zero-point quantum corrections lead to dominant prolate configurations in the 0{1/+}, 0{2/+}, 2{1/+} and 2{2/+} states of the studied nuclei. Moreover, those dynamical deformation effects provide an enhanced stability that further supports the mean-field predictions, corroborating a shift of the r-process path to higher neutron numbers. Beyond mean-field calculations provide a smaller shell gap at N = 126 than the mean-field one in good agreement with previous theoretical studies. However, the shell gap still remains strong enough in the two-neutron drip lines.

  12. Repetitive Solid Spherical Pellet Injection and Irradiation toward the Repetitive-mode Fast-Ignition Fusion miniReactor CANDY

    International Nuclear Information System (INIS)

    HANAYAMA, Ryohei; KOMEDA, Osamu; NISHIMURA, Yasuhiko; MORI, Yoshitaka; ISHII, Katsuhiro; NAKAYAMA, Suisei; OKIHARA, Shinichiro; FUJITA, Kazuhisa; SEKINE, Takashi; SATO, Nakahiro; KAWASHIMA, Toshiyuki; KAN, Hirofumi; KURITA, Takashi; NAKAMURA, Naoki; KONDO, Takuya; FUJINE, Manabu; AZUMA, Hirozumi; HIOKI, Tatsumi; KAKENO, Mitsutaka; MOTOHIRO, Tomoyoshi

    2016-01-01

    Pellet injection and repetitive laser illumination are key technologies for realizing inertial fusion energy [1-4]. Neutron generator using lasers also requires a repeating pellet target supplier. Here we present the first demonstration of target injection and neutron generation[5]. We injected more than 1300 spherical deuterated polystyrene(C 8 D 8 ) bead pellet targets during 23 minutes at 1 Hz(Fig. 1). After the pellet targets fell for a distance of 18 cm, we applied the synchronized laser-diode-pumped ultra-intense laser HAMA. The laser intensity at the focal point is 5 x 10 18 W/cm 2 , which is high enough to generate neutrons. As a result of the irradiation, we produced 2.45-MeV DD neutrons. Figure 2 shows the neutron time-of-flight signals detected by plastic scintillators coupled to photomultipliers. The neutron energy was calculated by the time-of-flight method. The maximum neutron yield was 9.5 x 10 4 /4π sr. The result is a step toward fusion power and also suggests possible industrial neutron sources. (paper)

  13. High-energy two-neutron removal from Be{sup 10}

    Energy Technology Data Exchange (ETDEWEB)

    Ashwood, N.I.; Freer, M.; Ahmed, S.; Clarke, N.M.; Curtis, N.; Soic, N.; Ziman, V.A. [Birmingham Univ., School of Physics and Astronomy, (United Kingdom); Millener, D.J. [Brookhaven National Lab., Upton, NY (United States); Orr, N.A.; Carstoiu, F.; Angelique, J.C.; Catford, W.N.; Lecouey, J.L.; Marques, F.M.; Normand, G.; Timis, C. [Caen Univ., Lab. de Physique Corpusculaire, ISMRA, IN2P3-CNRS, 14 (France); Carsoiu, F. [Horia Hulubei National institute of Physics and Nuclear Engineering (IFIN-HH), Bucharest-Magurele (Romania); Bouchat, V.; Hanappe, F.; Kerckx, Y.; Materna, T. [Universite Libre de Bruxelles (Belgium); Catford, W.N.; Pain, S.; Timis, C. [Surrey Univ., School of Electronics and Physical Sciences, Guildford (United Kingdom); Horoi, M. [Central Michigan Univ., Physics Dept., Mount Pleasant, MI (United States); Unshakova, A. [Joint Institute for Nuclear Research Dubna (Russian Federation)

    2005-09-15

    A kinetically complete measurement of the {sup 12}C({sup 10}Be, {alpha}+{alpha}+n) and ({sup 10}Be, {alpha}+{alpha}) reactions has been performed at a beam energy of 30 MeV/nucleon. The charged beam velocity particles were detected in an array of Si-CsI detectors placed at zero degrees, and the neutrons in an 81-element neutron array. The coincident detection of the final-state particles, produced in the breakup of {sup 10}Be, allowed the reconstruction of the excitation energy in the {sup 8}Be and {sup 9}Be systems. States in {sup 8}Be were identified, in particular the ground and first-excited states; and in {sup 9}Be, states at 1.68, 2.43, and (2.78, 3.05) MeV were observed. The population of these levels, in particular the 2.43 MeV 5/2- level, suggests that collective excitations play an important role in the neutron removal process. Distorted wave Born approximation and Glauber-type calculations have been used to model the direct neutron removal from the {sup 10}Be ground state and the two-step removal via inelastic excitations of the {sup 10}Be(2{sup +}) and {sup 9}Be(5/2{sup -}) excited states. (authors)

  14. Neutrons for global energy solutions. Book of abstracts

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-07-01

    The book of abstracts of the conference on neutrons for global energy solutions include contributions to the following topics: Views from politics: What do we need in European energy research: cooperation, large facilities, more science? Fundamental research for energy supply. View from the United States. View from industry: Neutrons for nuclear reactor development in transition stage between generation III and generation IV. Toyotas's expectations for neutron analysis. Instrumentation and cross cutting issues. Energy sources. Waste management and environment. Li ion batteries. Photovoltaics. Savings and catalysis. Fuel cells. Hydrogen storage.

  15. Neutrons for global energy solutions. Book of abstracts

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-07-01

    The book of abstracts of the conference on neutrons for global energy solutions include contributions to the following topics: Views from politics: What do we need in European energy research: cooperation, large facilities, more science? Fundamental research for energy supply. View from the United States. View from industry: Neutrons for nuclear reactor development in transition stage between generation III and generation IV. Toyotas's expectations for neutron analysis. Instrumentation and cross cutting issues. Energy sources. Waste management and environment. Li ion batteries. Photovoltaics. Savings and catalysis. Fuel cells. Hydrogen storage.

  16. Gamma/neutron competition above the neutron separation energy in delayed neutron emitters

    Directory of Open Access Journals (Sweden)

    Valencia E.

    2014-03-01

    Full Text Available To study the β-decay properties of some well known delayed neutron emitters an experiment was performed in 2009 at the IGISOL facility (University of Jyväskylä in Finland using Total Absorption γ-ray Spectroscopy (TAGS technique. The aim of these measurements is to obtain the full β-strength distribution below the neutron separation energy (Sn and the γ/neutron competition above. This information is a key parameter in nuclear technology applications as well as in nuclear astrophysics and nuclear structure. Preliminary results of the analysis show a significant γ-branching ratio above Sn.

  17. Research on neutron energy spectrum of the beryllium, iron and polyethylene shells assemblies injected by D-T neutron

    International Nuclear Information System (INIS)

    An, Li; Guo, Haiping; Wang, Xinhua

    2009-04-01

    To test a simulation code, the multi-shell assemblies were established, which were made of beryllium stainless steel and polyethylene from the interior to the outer. The symmetry axes are all in the line of the D + beam. The neutron energy spectra above 1 MeV were obtained in medium by the detector of stilbene crystal of φ18 min x 20 mm. The distance between source and the spherical surface was 30 cm and 50 cm. The measurement channels are in the angle 0 degree and 120 degree relative to D + beam direction. The measurement positions are 0 cm, 9.7 cm, 12.8 cm and 17.3 cm away from the center of the assembly in both directions. The spectrum in different positions of the multi-shell assemblies in medium were compared and analyzed. (authors)

  18. Investigation of Gas Solid Fluidized Bed Dynamics with Non-Spherical Particles

    Energy Technology Data Exchange (ETDEWEB)

    Choudhuri, Ahsan [Univ. of Texas, El Paso, TX (United States). Dept. of Mechanical Engineering

    2013-06-30

    One of the largest challenges for 21st century is to fulfill global energy demand while also reducing detrimental impacts of energy generation and use on the environment. Gasification is a promising technology to meet the requirement of reduced emissions without compromising performance. Coal gasification is not an incinerating process; rather than burning coal completely a partial combustion takes place in the presence of steam and limited amounts of oxygen. In this controlled environment, a chemical reaction takes place to produce a mixture of clean synthetic gas. Gas-solid fluidized bed is one such type of gasification technology. During gasification, the mixing behavior of solid (coal) and gas and their flow patterns can be very complicated to understand. Many attempts have taken place in laboratory scale to understand bed hydrodynamics with spherical particles though in actual applications with coal, the particles are non-spherical. This issue drove the documented attempt presented here to investigate fluidized bed behavior using different ranges of non-spherical particles, as well as spherical. For this investigation, various parameters are controlled that included particle size, bed height, bed diameter and particle shape. Particles ranged from 355 µm to 1180 µm, bed diameter varied from 2 cm to 7 cm, two fluidized beds with diameters of 3.4 cm and 12.4 cm, for the spherical and non-spherical shaped particles that were taken into consideration. Pressure drop was measured with increasing superficial gas velocity. The velocity required in order to start to fluidize the particle is called the minimum fluidization velocity, which is one of the most important parameters to design and optimize within a gas-solid fluidized bed. This minimum fluidization velocity was monitored during investigation while observing variables factors and their effect on this velocity. From our investigation, it has been found that minimum fluidization velocity is independent of bed

  19. Energy behaviour of neutrons generated by Witch-type distributed axi-symmetrical deuteron beams accelerated onto plane tritium targets

    International Nuclear Information System (INIS)

    Timus, D.M.; Bradley, D.A.; Timus, B.D.; Kalla, S.L.; Srivastava, H.M.

    2000-01-01

    This paper is an analytical study of the spatial dependency of the d-T neutron energy in the vicinity of a homogeneous tritium-occluded plane target. Close to the target, and along the path of incidence of axially symmetric deuteron beams, the transverse density of accelerated deuterons is assumed to be governed by a law approximated by the 'Witch' function. In particular circumstances, the elementary neutron emission process in non-dispersive media can be considered to be omni-directional (due consideration being paid to collision kinetics, depending upon mass and kinetic energy of particles involved in the nuclear collision, nuclear reaction energy, etc.). Consequently, analytical expressions can be considerably simplified. By applying the classical kinetic energy and momentum conservation laws to nuclear processes, a theoretical description is obtained, taking into account the exoergic character of d-T fusion reaction. A number of expressions for energetic prediction of the fast neutron field are proposed. The associated relations, involving elementary functions, can be investigated using a desk-top computer. Computationally tractable tools are of importance in the study of diverse situations such as induced reactions and activation analysis using 14 MeV neutron generators, investigations in health-physics, radiation dose measurements, nuclear medicine, damage effects, and simulation studies

  20. Determination of reactivity of multiplying systems filled with spherical HTGR-fuel elements using kinetic methods with regard to the pulsed-neutron method

    International Nuclear Information System (INIS)

    Drueke, V.

    1978-06-01

    At three critical or subcritical facilities - two of them filled with spherical HTGR-fuel elements - the reactivity is determined using kinetic methods. Besides the inverskinetic method the applicability of the pulsed-neutron method is investigated. The experimental results using the pulsed-neutron method are compared partly with the inverskinetic method and partly with diffusion-calculations. It is shown, that in the HTGR the space dependence of the reactivity in radial direction is not remarkable in spite of the 'kinetic distortion'; on the contrary in axial direction - the direction of the external neutron source - space dependent reactivity worths are measured. The results of the pulsed-neutron methods of Sjoestrand and Simmons-King are rather good applicable in all configurations. For the method of Sjoestrand it is necessary to select the detector positions, whereas for Simmons-King the calculated life-time determines the results. Therefore it is proposed to compare calculated and measured decay constants of the prompt neutron field in future. (orig.) [de

  1. Study of the parabolic-spherical shape on the energy resolution in gamma spectrometry

    International Nuclear Information System (INIS)

    Silva, Joao Carlos Pereira da

    1997-01-01

    In gamma spectrometry, the energy resolution is an important parameter. This parameter measures the capability of the system to separate two photopeaks that are together. Scintillation systems have various factors that affect the energy resolution: energy deposition, light emission, light collection and electric signal processing. Light collection depended on the mechanisms of light transport until light strikes on the photocathode. In this trajectory the light losses energy by attenuation and refractions on the surfaces. In order to minimize these effects, a parabolic-spherical shape is proposed. The energy resolutions of hemispherical and parabolic-spherical shapes were measured. The results show a better resolution for the new shape, about 33% for Compton edge due to a 137 Cs radioactive source. (author)

  2. Measurement of Neutron Energy Spectrum Emitted by Cf-252 Source Using Time-of-Flight Method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Cheol Ho; Son, Jaebum; Kim, Tae Hoon; Lee, Sangmin; Kim, Yong-Kyun [Hanyang University, Seoul (Korea, Republic of)

    2016-10-15

    The techniques proposed to detect the neutrons usually require the detection of a secondary recoiling nucleus in a scintillator (or other type of detector) to indicate the rare collision of a neutron with a nucleus. This is the same basic technique, in this case detection of a recoil proton that was used by Chadwick in the 1930 s to discover and identify the neutron and determine its mass. It is primary technique still used today for detection of fast neutron, which typically involves the use of a hydrogen based organic plastic or liquid scintillator coupled to a photo-multiplier tube. The light output from such scintillators is a function of the cross section and nuclear kinematics of the n + nucleus collision. With the exception of deuterated scintillators, the scintillator signal does not necessarily produce a distinct peak in the scintillator spectrum directly related to the incident neutron energy. Instead neutron time-of-flight (TOF) often must be utilized to determine the neutron energy, which requires generation of a prompt start signal from the nuclear source emitting the neutrons. This method takes advantage of the high number of prompt gamma rays. The Time-of-Flight method was used to measure neutron energy spectrum emitted by the Cf-252 neutron source. Plastic scintillator that has a superior discrimination ability of neutron and gamma-ray was used as a stop signal detector and liquid scintillator was used as a stat signal detector. In experiment, neutron and gamma-ray spectrum was firstly measured and discriminated using the TOF method. Secondly, neutron energy spectrum was obtained through spectrum analysis. Equation of neutron energy spectrum that was emitted by Cf-252 source using the Gaussian fitting was obtained.

  3. New sampling method in continuous energy Monte Carlo calculation for pebble bed reactors

    International Nuclear Information System (INIS)

    Murata, Isao; Takahashi, Akito; Mori, Takamasa; Nakagawa, Masayuki.

    1997-01-01

    A pebble bed reactor generally has double heterogeneity consisting of two kinds of spherical fuel element. In the core, there exist many fuel balls piled up randomly in a high packing fraction. And each fuel ball contains a lot of small fuel particles which are also distributed randomly. In this study, to realize precise neutron transport calculation of such reactors with the continuous energy Monte Carlo method, a new sampling method has been developed. The new method has been implemented in the general purpose Monte Carlo code MCNP to develop a modified version MCNP-BALL. This method was validated by calculating inventory of spherical fuel elements arranged successively by sampling during transport calculation and also by performing criticality calculations in ordered packing models. From the results, it was confirmed that the inventory of spherical fuel elements could be reproduced using MCNP-BALL within a sufficient accuracy of 0.2%. And the comparison of criticality calculations in ordered packing models between MCNP-BALL and the reference method shows excellent agreement in neutron spectrum as well as multiplication factor. MCNP-BALL enables us to analyze pebble bed type cores such as PROTEUS precisely with the continuous energy Monte Carlo method. (author)

  4. A Kinematically Beamed, Low Energy Pulsed Neutron Source for Active Interrogation

    International Nuclear Information System (INIS)

    Dietrich, D.; Hagmann, C.; Kerr, P.; Nakae, L.; Rowland, M.; Snyderman, N.; Stoeffl, W.; Hamm, R.

    2004-01-01

    We are developing a new active interrogation system based on a kinematically focused low energy neutron beam. The key idea is that one of the defining characteristics of SNM (Special Nuclear Materials) is the ability for low energy or thermal neutrons to induce fission. Thus by using low energy neutrons for the interrogation source we can accomplish three goals, (1) Energy discrimination allows us to measure the prompt fast fission neutrons produced while the interrogation beam is on; (2) Neutrons with an energy of approximately 60 to 100 keV do not fission 238U and Thorium, but penetrate bulk material nearly as far as high energy neutrons do and (3) below about 100keV neutrons lose their energy by kinematical collisions rather than via the nuclear (n,2n) or (n,n') processes thus further simplifying the prompt neutron induced background. 60 keV neutrons create a low radiation dose and readily thermal capture in normal materials, thus providing a clean spectroscopic signature of the intervening materials. The kinematically beamed source also eliminates the need for heavy backward and sideway neutron shielding. We have designed and built a very compact pulsed neutron source, based on an RFQ proton accelerator and a lithium target. We are developing fast neutron detectors that are nearly insensitive to the ever-present thermal neutron and neutron capture induced gamma ray background. The detection of only a few high energy fission neutrons in time correlation with the linac pulse will be a clear indication of the presence of SNM

  5. Target injection and engagement for neutron generation at 1 Hz

    International Nuclear Information System (INIS)

    Komeda, Osamu; Mori, Yoshitaka; Nishimura, Yasuhiko

    2013-01-01

    Target injection is a key technology to realizing inertial fusion energy. Here we present the first demonstration of target injection and neutron generation. We injected more than 600 spherical deuterated polystyrene (C 8 D 8 ) bead targets during 10 minutes at 1 Hz. After the targets fell for a distance of 18 cm, we applied the synchronized laser-diode-pumped ultra-intense laser HAMA and successfully generated neutrons repeatedly. The result is a step toward fusion power and also suggests possible industrial neutron sources. (author)

  6. Extended Lipkin-type models with residual proton-neutron interaction

    International Nuclear Information System (INIS)

    Stoica, S.

    1999-01-01

    Extended Lipkin-Meshkov-Glick (LMG) models for testing the Random Phase Approximation (RPA) and proton-neutron Random Phase Approximation (pnRPA) methods are developed taking into account explicitly the proton and neutron degrees of freedom. First, an extended LMG model for testing RPA is developed. The proton and neutron Hamiltonians are taken to be of the LMG form and, in addition, a residual proton-neutron interaction is included. Exact solutions in a SU(2) x SU(2) basis as well as the RPA solutions for the energy spectrum of the model Hamiltonian are obtained. Then, the behaviour of the first collective excited state is studied as a function of the interaction parameters of the model using the exact and RPA methods. Secondly, an extended LMG model for testing pnRPA method is developed. Besides the proton and neutron single particle terms two types of residual proton-neutron interactions, one simulating a particle-particle and the other a particle-hole interaction, are included in the model Hamiltonian, so that the model is exactly solvable in an isospin SU(2) x SU(2) basis. The exact and pnRPA spectra of the model Hamiltonian are calculated as a function of the model parameters and compared to each other. Furthermore, charge-changing operators simulating a nuclear beta decay and their action on eigenfunctions of the model Hamiltonian are defined, and transition amplitude of them are calculated using exact and pnRPA wave functions. The best agreement between the exact RPA-type calculations for spectra and transitions, was obtained when the correlated RPA ground state, instead of the uncorrelated HF ground state was employed and when both kinds of residual interactions (i.e. like- and unlike-particle two-body interactions) are included in the model Hamiltonians. (author)

  7. Fast neutron spectroscopy by gas proton-recoil methods at the light water reactor pressure vessel simulator

    International Nuclear Information System (INIS)

    Rogers, J.W.

    1980-10-01

    Fast neutron spectrum measurements were made in a Light Water Reactor (LWR) Pressure Vessel Simulator (PVS) to provide neutron spectral definition required to appropriately perform and interpret neutron dosimetry measurements related to fast neutron damage in LWR-PV steels. Proton-recoil proportional counter methods using hydrogen and methane gas-filled detectors were applied to obtain the proton spectra from which the neutron spectra were derived. Cylindrical and spherical geometry detectors were used to cover the neutron energy range between 50 keV and 2 MeV. Results show that the neutron spectra shift in energy distribution toward lower energy between the front and back of a PVS. The relative neutron flux densities increase in this energy range with increasing thickness of the steel. Neutron spectrum fine structure shapes and changes are observed. These results should assist in the generation of more accurate effective cross sections and fluences for use in LWR-PV fast neutron dosimetry and materials damage analyses

  8. Improving neutron multiplicity counting for the spatial dependence of multiplication: Results for spherical plutonium samples

    Energy Technology Data Exchange (ETDEWEB)

    Göttsche, Malte, E-mail: malte.goettsche@physik.uni-hamburg.de; Kirchner, Gerald

    2015-10-21

    The fissile mass deduced from a neutron multiplicity counting measurement of high mass dense items is underestimated if the spatial dependence of the multiplication is not taken into account. It is shown that an appropriate physics-based correction successfully removes the bias. It depends on four correction coefficients which can only be exactly determined if the sample geometry and composition are known. In some cases, for example in warhead authentication, available information on the sample will be very limited. MCNPX-PoliMi simulations have been performed to obtain the correction coefficients for a range of spherical plutonium metal geometries, with and without polyethylene reflection placed around the spheres. For hollow spheres, the analysis shows that the correction coefficients can be approximated with high accuracy as a function of the sphere's thickness depending only slightly on the radius. If the thickness remains unknown, less accurate estimates of the correction coefficients can be obtained from the neutron multiplication. The influence of isotopic composition is limited. The correction coefficients become somewhat smaller when reflection is present.

  9. Independent fission yields of Rb and Cs from thermal-neutron-induced fission of 239Pu

    International Nuclear Information System (INIS)

    Balestrini, S.J.; Forman, L.

    1975-01-01

    The relative independent fission yields of Rb and Cs from thermal-neutron-induced fission of 239 Pu have been measured on line using a mass spectrograph and thermalized neutrons from a burst reactor. Independent yields were derived by normalizing the measurements to products of chain yields and fractional independent yields, estimating the latter from measured cumulative yields of Kr and Xe. Comparing the independent yields with those from 238 U fission, the 239 Pu results show shifts in isotopic yield distribution toward lower mass for both Rb and Cs and also toward the production of more Cs and less Rb when 239 Pu is fissioned

  10. Quality factor calculations for neutron spectra below 4 MeV

    International Nuclear Information System (INIS)

    Borak, T.B.; Stinchcomb, T.G.

    1979-01-01

    A method is described for computing the distribution of absorbed dose, D(L), as a function of linear energy transfer, L, for any neutron spectrum with energies below 4 MeV. The results are used to determine the average quality factor for two distinctly different neutron spectra using the ICRP recommended values of the quality factor, Q(L). A comparison is made between the calculations and measurements of D(L) using a spherical tissue equivalent proportional counter. Heavy ion recoil contributions to the average quality factor are examined in detail. (author)

  11. On the origin of low energy tail for monoenergetic neutron sources

    International Nuclear Information System (INIS)

    Kornilov, N.V.; Kagalenko, A.B.

    1995-01-01

    The problems of data processing when measuring inelastic neutron scattering cross sections for separated nuclei levels are studied. The model describing the neutron energy distribution for monoenergetic neutron sources is developed. The factors which make the major contributions into spectrometer response function formation are discussed. It is shown that the model considered predicts well neutron energy distribution from metal Li-target. The model parameters should be estimated on the basis of the experimental data. The neutron scattering on target environment contributes much into the low energy region of the neutron spectrum. An additional neutron source is introduced into the model in order to describe the low energy peak asymmetry (the so-called low energy tail). The tail neutron contribution dependence on incident energy and angle turns out to be rather unexpected. The conclusion is made that it is difficult to explain the origin and the properties of the tail neutron source by slit proton scattering or some Li-nuclei distribution regularities. 3 refs., 6 figs

  12. Study on the exposure of spherical microtargets to a (1-3) TW iodine laser pulse

    International Nuclear Information System (INIS)

    Zaretskij, A.I.; Kirillov, G.A.; Kormer, S.B.; Kochemasov, G.G.; Murugov, V.M.; Sukharev, S.A.

    1983-01-01

    Investigations carried out at the photo dissociation iodine laser ''Iskra-4'' (PIL) with the aim of improving laser parameters and studying the interaction of laser radiation with microtargets filled with TD gas, are reviewed. PIL ''Iskra-4'' has the radiation energy maximum in the world of approximately 1.8 kJ in one beam with the light aperture approximately 60 cm, pulse duration approximately 0.8 ns, beam divergence theta approximately 0.3-0.4 mrad and the contrast more than 10 6 . A good direction of laser radiation is achieved due to . the optimization of the composition of working medium, pressure of its components, and other factors that permits to minimize the gradient of refraction index without considerable reduction of the stored energy. The problem of selecting the regime of affecting of the ''exploding shell'' type and obtaining of short duration pulses is generally considered. The assigning generator and results of experiments into irradiation of spherical microtargets filled with DT gas are described. The neutron yield of up to 10 6 neutrons in the case of 50 time volumetric compression is obtained for the first time with the aid of PIL

  13. Energy response study of modified CR-39 neutron personnel dosimeter

    International Nuclear Information System (INIS)

    Sathian, Deepa; Bakshi, A.K.; Datta, D.; Nair, Sreejith S.; Sathian, V.; Mishra, Jitendra; Sen, Meghnath

    2018-01-01

    Personnel neutron dosimetry is an integral part of radiation protection. No single dosimeter provides the satisfactory energy response, sensitivity, angular dependence characteristics and accuracy necessary to meet the requirement of an ideal personnel neutron dosimeter. The response of a personnel neutron dosimeter is critically dependent upon the energy distribution of the neutron field. CR-39 personnel neutron dosimeters were typically calibrated in the standard neutron field of 252 Cf and 241 Am-Be in our laboratory, although actual neutron fields may vary from the calibration neutron spectrum. Recently the badge cassette of the personnel neutron dosimeter was changed due to frequent damage of the PVC badge used earlier. This paper discusses energy response of CR-39 solid state nuclear track detector loaded in this modified badge cassette as per latest ISO recommendation

  14. Measurements of the energy spectrum of backscattered fast neutrons

    International Nuclear Information System (INIS)

    Segal, Y.

    1976-03-01

    Experimental measurements have been made of the energy spectra of neutrons transmitted through slabs of iron, lead and perspex for incident neutron energies of 0.5, 1.0, 1.5 and 1.8 MeV. The neutron energy measurements were made using a He-3 spectrometer. The dependence of the neutrons energy spectrum as a function of scattering thickness was determined. The neutrons source used was a 3MeV Van de Graaff accelerator with a tritium target using the H 3 (p,n) He 3 reaction. The results obtained by the investigator on energy dependence of transmitted neutrons as a function of thickness of scattering material were compared, where possible, with the results obtained by other workers. The comparisons indicated good agreement. The experiment's results are compared with MORSE Monte Carlo calculated values. It is worthwhile to note that direct comparison between measured cross section values and the recommended ones are very far from satisfactory. In almost all cases the calculated spectrum is harder than the experimental one, a situation common to the penetrating and the back-scattered flux

  15. Estimation of neutron energy distributions from prompt gamma emissions

    Science.gov (United States)

    Panikkath, Priyada; Udupi, Ashwini; Sarkar, P. K.

    2017-11-01

    A technique of estimating the incident neutron energy distribution from emitted prompt gamma intensities from a system exposed to neutrons is presented. The emitted prompt gamma intensities or the measured photo peaks in a gamma detector are related to the incident neutron energy distribution through a convolution of the response of the system generating the prompt gammas to mono-energetic neutrons. Presently, the system studied is a cylinder of high density polyethylene (HDPE) placed inside another cylinder of borated HDPE (BHDPE) having an outer Pb-cover and exposed to neutrons. The emitted five prompt gamma peaks from hydrogen, boron, carbon and lead can be utilized to unfold the incident neutron energy distribution as an under-determined deconvolution problem. Such an under-determined set of equations are solved using the genetic algorithm based Monte Carlo de-convolution code GAMCD. Feasibility of the proposed technique is demonstrated theoretically using the Monte Carlo calculated response matrix and intensities of emitted prompt gammas from the Pb-covered BHDPE-HDPE system in the case of several incident neutron spectra spanning different energy ranges.

  16. Spherically symmetric solution and a satisfactory energy-momentum complex

    International Nuclear Information System (INIS)

    Nashed, G.G.L.

    2005-01-01

    Mikhail et al. obtained two spherically symmetric solution in Moeller tetrad theory of gravitation. They calculated their energy content and obtained a strange value for the second solution, in spite that the associated metric of these solutions is the same (the Schwarzschild metric). We use another method given bu Gibbons and Hawking to calculate the energy content of these solutions. We also obtained a strange value of energy for the second solution. Studying the requirements of the satisfactory energy-momentum complex given by Moeller we find that the second solution which behaves as 1/√r does not transform as a four-vector under Lorentz transformation

  17. Energy measurement of prompt fission neutrons in 239Pu(n,f) for incident neutron energies from 1 to 200 MeV

    CERN Document Server

    Chatillon, A; Granier, Th; Laurent, B; Taïeb, J; Noda, S; Haight, R C; Devlin, M; Nelson, R O; O’Donnell, J M

    2010-01-01

    Prompt fission neutron spectra in the neutron-induced fission of 239Pu have been measured for incident neutron energies from 1 to 200 MeV at the Los Alamos Neutron Science Center. Preliminary results are discussed and compared to theoretical model calculation.

  18. Production of gamma ray bursts from asymmetric core combustion of magnetized young neutron stars

    Science.gov (United States)

    de Gouveia dal Pino, E. M.; Lugones, G.; Horvath, J. E.; Ghezzi, C. R.

    2005-09-01

    Many works in the past have explored the idea that the conversion of hadronic matter into strange quark matter in neutron stars may be an energy source for GRBs (see references in Lugones et al. 2002, Lugones and Horvath 2003). These models addressed essentially spherically symmetric conversions of the whole neutron star rendering isotropic gamma emission. Accumulating observational evidence suggests that at least ''long'' GRBs are strongly asymmetric, jet-like outflows. The ''short'' burst subclass is not obviously asymmetric, and they may actually be spherically symmetric if the sources are close enough. A new potentially important feature recently recognized (Lugones et al. 2002) is that if a conversion to strange quark matter actually begins near the center of a neutron star, the presence of a magnetic field with intensity B ˜ 1013 G (see also Ghezi, de Gouveia Dal Pino & Horvath 2004) will originate a prompt collimated gamma emission, which may be observed as a short, beamed GRB after the recovery of a fraction of the neutrino energy via ν {barν} → e+e- → γγ. The calculations show that the neutrino luminosity is ˜ 1053 erg/sec and that the e+e- luminosity is about two orders of magnitude smaller ( tet{Lugones2002grb}). We find that 90 % of the e+e- pairs are injected inside small cylinders located just above the polar caps (with radius δ and height 0.4 R) in a timescale of τi ≃ 0.2 s almost independently of the initial temperature. This provides an interesting suitable explanation for the inner engine of short gamma ray bursts.

  19. Neutron spectra measurement and calculations using data libraries CIELO, JEFF-3.2 and ENDF/B-VII.1 in iron benchmark assemblies

    Science.gov (United States)

    Jansky, Bohumil; Rejchrt, Jiri; Novak, Evzen; Losa, Evzen; Blokhin, Anatoly I.; Mitenkova, Elena

    2017-09-01

    The leakage neutron spectra measurements have been done on benchmark spherical assemblies - iron spheres with diameter of 20, 30, 50 and 100 cm. The Cf-252 neutron source was placed into the centre of iron sphere. The proton recoil method was used for neutron spectra measurement using spherical hydrogen proportional counters with diameter of 4 cm and with pressure of 400 and 1000 kPa. The neutron energy range of spectrometer is from 0.1 to 1.3 MeV. This energy interval represents about 85 % of all leakage neutrons from Fe sphere of diameter 50 cm and about of 74% for Fe sphere of diameter 100 cm. The adequate MCNP neutron spectra calculations based on data libraries CIELO, JEFF-3.2 and ENDF/B-VII.1 were done. Two calculations were done with CIELO library. The first one used data for all Fe-isotopes from CIELO and the second one (CIELO-56) used only Fe-56 data from CIELO and data for other Fe isotopes were from ENDF/B-VII.1. The energy structure used for calculations and measurements was 40 gpd (groups per decade) and 200 gpd. Structure 200 gpd represents lethargy step about of 1%. This relatively fine energy structure enables to analyze the Fe resonance neutron energy structure. The evaluated cross section data of Fe were validated on comparisons between the calculated and experimental spectra.

  20. Determination for energy response and directionality of neutron survey meters

    International Nuclear Information System (INIS)

    Chen Changmao; Liu Jinhua; Xie Jianlun; Su Jingling

    1992-01-01

    The energy response and directionality of neutron survey meter type MK7 and 2202D are determined. The reactor thermal column beam, reactor filtered beams (6 eV, 24.4 keV and 144 keV), 226 Ra-Be, 241 Am-Be, 252 Cf and its moderated sources are used for the measurement. The results shows: the survey meters are influenced obviously by the direction; the response of middle-energy region is large, the energy response of 2202D is better than MK7

  1. Measurement of the neutron and gamma-ray spectra originating from a 14-MeV neutron source in liquid nitrogen and liquid air

    International Nuclear Information System (INIS)

    Broecker, B.; Clausen, K.; Schneider-Kuehnle, P.; Weinert, M.

    1975-01-01

    An experiment to measure the radiation transport originating from a 14-MeV neutron source in liquid nitrogen and liquid air is presented. Neutron and gamma-ray spectra were measured with a proton-recoil NE 213 scintillator and with four spherical proportional counters in a tank filled with liquid nitrogen or liquid air. The neutron spectra cover the energy range of 20 keV to 18 MeV. The source-detector separation varies in the liquid medium between 60 and 240 cm. The experimental setup is briefly described and the errors are estimated. (2 tables, 9 figures) (auth)

  2. Energy levels and electron g-factor of spherical quantum dots with Rashba spin-orbit interaction

    International Nuclear Information System (INIS)

    Vaseghi, B.; Rezaei, G.; Malian, M.

    2011-01-01

    We have studied simultaneous effects of Rashba spin-orbit interaction and external electric and magnetic fields on the subbands energy levels and electron g-factor of spherical quantum dots. It is shown that energy eigenvalues strongly depend on the combined effects of external electric and magnetic fields and spin-orbit interaction strength. The more the spin-orbit interaction strength increase, the more the energy eigenvalues increase. Also, we found that the electron g-factor sensitively differers from the bulk value due to the confinement effects. Furthermore, external fields and spin-orbit interaction have a great influence on this important quantity. -- Highlights: → Energy of spherical quantum dots depends on the spin-orbit interaction strength in external electric and magnetic fields. → Spin-orbit interaction shifts the energy levels. → Electron g-factor differs from the bulk value in spherical quantum dots due to the confinement effects. → Electron g-factor strongly depends on the spin-orbit interaction strength in external electric and magnetic fields.

  3. Neutron resonance transmission spectroscopy with high spatial and energy resolution at the J-PARC pulsed neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Tremsin, A.S., E-mail: ast@ssl.berkeley.edu [University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States); Shinohara, T.; Kai, T.; Ooi, M. [Japan Atomic Energy Agency, 2–4 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Kamiyama, T.; Kiyanagi, Y.; Shiota, Y. [Hokkaido University, Kita 13 Nishi 8 Kita-ku, Sapporo-shi, Hokkaido 060-8628 (Japan); McPhate, J.B.; Vallerga, J.V.; Siegmund, O.H.W. [University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States); Feller, W.B. [NOVA Scientific, Inc., 10 Picker Rd., Sturbridge, MA 01566 (United States)

    2014-05-11

    The sharp variation of neutron attenuation at certain energies specific to particular nuclides (the lower range being from ∼1 eV up to ∼1 keV), can be exploited for the remote mapping of element and/or isotope distributions, as well as temperature probing, within relatively thick samples. Intense pulsed neutron beam-lines at spallation sources combined with a high spatial, high-timing resolution neutron counting detector, provide a unique opportunity to measure neutron transmission spectra through the time-of-flight technique. We present the results of experiments where spatially resolved neutron resonances were measured, at energies up to 50 keV. These experiments were performed with the intense flux low background NOBORU neutron beamline at the J-PARC neutron source and the high timing resolution (∼20 ns at epithermal neutron energies) and spatial resolution (∼55 µm) neutron counting detector using microchannel plates coupled to a Timepix electronic readout. Simultaneous element-specific imaging was carried out for several materials, at a spatial resolution of ∼150 µm. The high timing resolution of our detector combined with the low background beamline, also enabled characterization of the neutron pulse itself – specifically its pulse width, which varies with neutron energy. The results of our measurements are in good agreement with the predicted results for the double pulse structure of the J-PARC facility, which provides two 100 ns-wide proton pulses separated by 600 ns, broadened by the neutron energy moderation process. Thermal neutron radiography can be conducted simultaneously with resonance transmission spectroscopy, and can reveal the internal structure of the samples. The transmission spectra measured in our experiments demonstrate the feasibility of mapping elemental distributions using this non-destructive technique, for those elements (and in certain cases, specific isotopes), which have resonance energies below a few keV, and with lower

  4. Heat transfer enhancement in energy storage in spherical capsules filled with paraffin wax and metal beads

    International Nuclear Information System (INIS)

    Ettouney, Hisham; Alatiqi, Imad; Al-Sahali, Mohammad; Al-Hajirie, Khalida

    2006-01-01

    Energy storage is an attractive option to conserve limited energy resources, where more than 50% of the generated industrial energy is discarded in cooling water and stack gases. This study focuses on the evaluation of heat transfer enhancement in phase change energy storage units. The experiments are performed using spherical capsules filled with paraffin wax and metal beads. The experiments are conducted by inserting a single spherical capsule filled with wax and metal beads in a stream of hot/cold air. Experimental measurements include the temperature field within the spherical capsule and in the air stream. To determine the enhancement effects of the metal beads, the measured data is correlated against those for a spherical capsule filled with pure wax. Data analysis shows a reduction of 15% in the melting and solidification times upon increasing the number and diameter of the metal beads. This reduction is caused by a similar decrease in the thermal load of the sphere due to replacement of the wax by metal beads. The small size of the spherical capsule limits the enhancement effects; this is evident upon comparison of the heat transfer in a larger size, double pipe energy storage unit, where 2% of the wax volume is replaced with metal inserts, result in a three fold reduction in the melting/solidification time and a similar enhancement in the heat transfer rate

  5. Estimating the energy independence of a municipal wastewater treatment plant incorporating green energy resources

    International Nuclear Information System (INIS)

    Chae, Kyu-Jung; Kang, Jihoon

    2013-01-01

    Highlights: • We estimated green energy production in a municipal wastewater treatment plant. • Engineered approaches in mining multiple green energy resources were presented. • The estimated green energy production accounted for 6.5% of energy independence in the plant. • We presented practical information regarding green energy projects in water infrastructures. - Abstract: Increasing energy prices and concerns about global climate change highlight the need to improve energy independence in municipal wastewater treatment plants (WWTPs). This paper presents methodologies for estimating the energy independence of a municipal WWTP with a design capacity of 30,000 m 3 /d incorporating various green energy resources into the existing facilities, including different types of 100 kW photovoltaics, 10 kW small hydropower, and an effluent heat recovery system with a 25 refrigeration ton heat pump. It also provides guidance for the selection of appropriate renewable technologies or their combinations for specific WWTP applications to reach energy self-sufficiency goals. The results showed that annual energy production equal to 107 tons of oil equivalent could be expected when the proposed green energy resources are implemented in the WWTP. The energy independence, which was defined as the percent ratio of green energy production to energy consumption, was estimated to be a maximum of 6.5% and to vary with on-site energy consumption in the WWTP. Implementing green energy resources tailored to specific site conditions is necessary to improve the energy independence in WWTPs. Most of the applied technologies were economically viable primarily because of the financial support under the mandatory renewable portfolio standard in Korea

  6. Self-energy dispersion effects on neutron matter superfluidity

    International Nuclear Information System (INIS)

    Zuo Wei

    2001-01-01

    The effects of the dispersion and ground state correlation of the single particle self-energy on neutron matter superfluidity have been investigated in the framework of the Extended Brueckner-Hartree-Fock and the generalized BCS approaches. A sizable reduction of the energy gap is found due to the energy dependence of the self-energy. And the inclusion of the ground state correlations in the self-energy suppresses further the neutron matter superfluidity

  7. Study on the energy response to neutrons for a new scintillating-fiber-array neutron detector

    CERN Document Server

    Zhang Qi; Wang Qun; Xie Zhong Shen

    2003-01-01

    The energy response of a new scintillating-fiber-array neutron detector to neutrons in the energy range 0.01 MeV<=E sub n<=14 MeV was modeled by combining a simplified Monte Carlo model and the MCNP 4b code. In order to test the model and get the absolute sensitivity of the detector to neutrons, one experiment was carried out for 2.5 and 14 MeV neutrons from T(p,n) sup 3 He and T(d,n) sup 4 He reactions at the Neutron Generator Laboratory at the Institute of Modern Physics, the Chinese Academy of Science. The absolute neutron fluence was obtained with a relative standard uncertainty 4.5% or 2.0% by monitoring the associated protons or sup 4 He particles, respectively. Another experiment was carried out for 0.5, 1.0, 1.5, 2.0, 2.5 MeV neutrons from T(p,n) sup 3 He reaction, and for 3.28, 3.50, 4.83, 5.74 MeV neutrons from D(d,n) sup 3 He reaction on the Model 5SDH-2 accelerator at China Institute of Atomic Energy. The absolute neutron fluence was obtained with a relative standard uncertainty 5.0% by usin...

  8. Response of Moxon-Rae type gamma detectors for neutron capture cross section measurements

    International Nuclear Information System (INIS)

    Iyengar, K.V.K.; Lal, B.; Jhingan, M.L.

    1974-01-01

    A detector devised by Moxon and Rae for the absolute measurement of (n,γ) cross sections is briefly described. This detector is supposed to have an efficiency per MeV of γ-ray energy independent of the energy of the γ-rays. Such a detector consists of an electron converter placed before a thin plastic scintillator which detects the electron emitted by interaction of the γ-ray in the converter. The performance of this type of detector depends on the thickness and composition of the converter. Detailed Monte-Carlo calculations of the response for γ-ray energies from 0.2 to 12 MeV has been carried out for elements ranging from C to Bi and for a mixture of elements as well as for a mixture of an element plus compound, to find out the suitable material and thickness of the converter. Among the elements studied for the converter, Ni, Mo and Sn have a uniform response over the photon energy range 1-12 MeV. Out of these elements Mo has a low neutron capture cross section in the energy range 1-1000 keV and is thus to be preferred. A mixture of C + Bi 2 O 3 in the weight ratio 11.6 : 88.4 gives a uniform response over the photon energy range 1-12 MeV. (K.B.)

  9. Neutron energy response measurement of scintillation detectors

    International Nuclear Information System (INIS)

    Yang Hongqiong; Peng Taiping; Yang Jianlun; Tang Zhengyuan; Yang Gaozhao; Li Linbo; Hu Mengchun; Wang Zhentong; Zhang Jianhua; Li Zhongbao; Wang Lizong

    2004-01-01

    Neutron sensitivities of detectors composed of plastic scintillator ST401, ST1422, ST1423 and phyotomultiplier tube in primary energy range of fission neutron are calibrated by direct current. The energy response curve of the detectors is obtained in this experiment. The experimental result has been compared with the theoretical calculation and they are in agreement within measuring uncertainty. (authors)

  10. Resonance energy transfer: The unified theory via vector spherical harmonics

    Energy Technology Data Exchange (ETDEWEB)

    Grinter, Roger, E-mail: r.grinter@uea.ac.uk; Jones, Garth A., E-mail: garth.jones@uea.ac.uk [School of Chemistry, University of East Anglia, Norwich NR4 7TJ (United Kingdom)

    2016-08-21

    In this work, we derive the well-established expression for the quantum amplitude associated with the resonance energy transfer (RET) process between a pair of molecules that are beyond wavefunction overlap. The novelty of this work is that the field of the mediating photon is described in terms of a spherical wave rather than a plane wave. The angular components of the field are constructed in terms of vector spherical harmonics while Hankel functions are used to define the radial component. This approach alleviates the problem of having to select physically correct solution from non-physical solutions, which seems to be inherent in plane wave derivations. The spherical coordinate system allows one to easily decompose the photon’s fields into longitudinal and transverse components and offers a natural way to analyse near-, intermediate-, and far-zone RET within the context of the relative orientation of the transition dipole moments for the two molecules.

  11. Measured operational neutron energies of compound refractive lenses

    Energy Technology Data Exchange (ETDEWEB)

    Park, H. [Adelphi Technology Inc., 981-B Industrial Road, San Carlos, CA 94070 (United States)]. E-mail: hpark@adelphitech.com; Cremer, J.T. [Adelphi Technology Inc., 981-B Industrial Road, San Carlos, CA 94070 (United States); Piestrup, M.A. [Adelphi Technology Inc., 981-B Industrial Road, San Carlos, CA 94070 (United States); Gary, C.K. [Adelphi Technology Inc., 981-B Industrial Road, San Carlos, CA 94070 (United States); Hjelm, Rex P. [Los Alamos Neutron Science Center (LANSCE), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Sellyey, W.C.L.J. [Los Alamos Neutron Science Center (LANSCE), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Pantell, R.H. [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States)

    2006-10-15

    The characteristics of two compound refractive lenses (CRLs) have been measured using a broadband spallation neutron source. One CRL consists of a stack of 98 biconcave, spherical lenses made of MgF{sub 2}, and another consists of 198 biconcave, spherical lenses made of Al. The bandwidth of the spallation source included wavelengths from 1.5 A to 15.7 A that we could use to test the CRLs. The MgF{sub 2} CRL was found to be useful from 9 to 15 A with the maximum transmission around 13 A, whereas the Al CRL was found to give good transmission around 5-15 A, with the maximum transmission around 8 A. Spectra with Al lens and MgF{sub 2} CRLs show multiple transmission dips due to Bragg diffraction of the microcrystal structure of the lens materials (Al or MgF{sub 2}). These measurements helped characterize the CRLs for possible applications at shorter wavelengths than previously used.

  12. High energy neutron dosimetry for the fusion program

    International Nuclear Information System (INIS)

    Barr, D.W.; Norris, A.E.

    1977-01-01

    Neutron dosimetry by the foil activation method offers a flexible technique for characterizing neutron spectra ranging from thermal energies to 30 MeV with the potential for extension to higher neutron energies as investigated by the Los Alamos Radiochemistry Group at the Los Alamos Meson Physics Facility and in the Apollo-Soyuz Test Project. The use of this method for the neutron flux description in thermal, resonance, and fission spectrum assemblies has been demonstrated. An extension of the method to environments involving thermonuclear processes was developed at Los Alamos in the early 1950's to characterize mixed fission-thermonuclear systems

  13. Density slope of the nuclear symmetry energy from the neutron skin thickness of heavy nuclei

    International Nuclear Information System (INIS)

    Chen Liewen; Ko Che Ming; Xu Jun; Li Baoan

    2010-01-01

    Expressing explicitly the parameters of the standard Skyrme interaction in terms of the macroscopic properties of asymmetric nuclear matter, we show in the Skyrme-Hartree-Fock approach that unambiguous correlations exist between observables of finite nuclei and nuclear matter properties. We find that existing data on neutron skin thickness Δr np of Sn isotopes give an important constraint on the symmetry energy E sym (ρ 0 ) and its density slope L at saturation density ρ 0 . Combining these constraints with those from recent analyses of isospin diffusion and the double neutron/proton ratio in heavy-ion collisions at intermediate energies leads to a more stringent limit on L approximately independent of E sym (ρ 0 ). The implication of these new constraints on the Δr np of 208 Pb as well as the core-crust transition density and pressure in neutron stars is discussed.

  14. Dose Evaluation of Neutron within Containment Building of a CE type Nuclear Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Wook; Han, Jae Mun; Kim, Kyung Doek; Yun, Cheol Whan; Suh, Jang Soo; Kim, Young Jae [Nuclear Environment Technology Institute, Daejeon (Korea, Republic of)

    2005-03-15

    From measured results of the neutron fields at some principal places within the containment building in a CE type nuclear power plant in operation, the radiation exposure of a worker to the neutron at there was evaluated and the equivalent dose reflecting new recommendation (ICRP 60) was compared with that doing the old one (ICRP 26). The measured neutron field was also compared with calibration neutron field. From the analysis, the following conclusion was obtained: the average neutron radiation weighting factor according to new recommendation is 2.41 to 2.71 times higher than the old one. The average neutron radiation weighting factor at the measured place was similar to that at calibration neutron field. The average neutron energy at measured place was between 42 and 158 keV and higher than that of calibration field of 500 keV. So, the measured equivalent dose in nuclear power plant could be overestimated compared to the real equivalent dose.

  15. Neutron spectrum perturbations due to scattering materials and their effect on the average neutron energy, the spectral index, and the hardness parameter

    International Nuclear Information System (INIS)

    Wright, H.L.; Meason, J.L.; Wolf, M.; Harvey, J.T.

    1976-01-01

    Measurements have been performed on the perturbing effect of a number of scattering materials by the 'free-field' neutron leakage spectrum from a Godiva Type Critical Assembly (White Sands Missile Range Fast Burst Reactor). The results of these measurements are interpreted in relation to some of the general parameters characterizing a neutron environment, namely, the average neutron energy >10 KeV, the spectral index and the hardness parameter. Three neutron spectrum measurements have been performed, each under different experimental configurations of scattering materials. Results from these measurements show the following with relation to the spectral index: (1) The neutron environment on the core surface and at 12-inches from the core surface (free-field) yield a spectral index of 6.8, (2) The neutron environment behind a 4.75-inch Plexiglas plate yield 4.6 for the spectral index and (3) The neutron environment behind a 2-inch aluminum plate yield 6.7 for the spectral index. It is concluded that the core surface and the 12-inch from core surface neutron environment are identical with the 'free-field' neutron environment at 20-inches when considering only those neutrons with energy >10 KeV. On the other hand, it appears that the 4.75 inches of Plexiglas severely perturbs the 'free-field' neutron environment, i.e., a much harder neutron spectrum >10 KeV. In the situation where 2-inches of aluminum is used as the perturbing medium, essentially no change in the neutron spectrum >10 KeV is noted

  16. Symmetry Parameter Constraints from a Lower Bound on Neutron-matter Energy

    Energy Technology Data Exchange (ETDEWEB)

    Tews, Ingo [Institute for Nuclear Theory, University of Washington, Seattle, WA 98195-1550 (United States); Lattimer, James M. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States); Ohnishi, Akira [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Kolomeitsev, Evgeni E., E-mail: itews@uw.edu, E-mail: james.lattimer@stonybrook.edu, E-mail: ohnishi@yukawa.kyoto-u.ac.jp, E-mail: e.kolomeitsev@gsi.de [Faculty of Natural Sciences, Matej Bel University, Tajovskeho 40, SK-97401 Banska Bystrica (Slovakia)

    2017-10-20

    We propose the existence of a lower bound on the energy of pure neutron matter (PNM) on the basis of unitary-gas considerations. We discuss its justification from experimental studies of cold atoms as well as from theoretical studies of neutron matter. We demonstrate that this bound results in limits to the density-dependent symmetry energy, which is the difference between the energies of symmetric nuclear matter and PNM. In particular, this bound leads to a lower limit to the volume symmetry energy parameter S {sub 0}. In addition, for assumed values of S {sub 0} above this minimum, this bound implies both upper and lower limits to the symmetry energy slope parameter L , which describes the lowest-order density dependence of the symmetry energy. A lower bound on neutron-matter incompressibility is also obtained. These bounds are found to be consistent with both recent calculations of the energies of PNM and constraints from nuclear experiments. Our results are significant because several equations of state that are currently used in astrophysical simulations of supernovae and neutron star mergers, as well as in nuclear physics simulations of heavy-ion collisions, have symmetry energy parameters that violate these bounds. Furthermore, below the nuclear saturation density, the bound on neutron-matter energies leads to a lower limit to the density-dependent symmetry energy, which leads to upper limits to the nuclear surface symmetry parameter and the neutron-star crust–core boundary. We also obtain a lower limit to the neutron-skin thicknesses of neutron-rich nuclei. Above the nuclear saturation density, the bound on neutron-matter energies also leads to an upper limit to the symmetry energy, with implications for neutron-star cooling via the direct Urca process.

  17. Kaon condensates, nuclear symmetry energy and cooling of neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Kubis, S. E-mail: kubis@alf.ifj.edu.pl; Kutschera, M

    2003-06-02

    The cooling of neutron stars by URCA processes in the kaon-condensed neutron star matter for various forms of nuclear symmetry energy is investigated. The kaon-nucleon interactions are described by a chiral Lagrangian. Nuclear matter energy is parametrized in terms of the isoscalar contribution and the nuclear symmetry energy in the isovector sector. High density behaviour of nuclear symmetry energy plays an essential role in determining the composition of the kaon-condensed neutron star matter which in turn affects the cooling properties. We find that the symmetry energy which decreases at higher densities makes the kaon-condensed neutron star matter fully protonized. This effect inhibits strongly direct URCA processes resulting in slower cooling of neutron stars as only kaon-induced URCA cycles are present. In contrast, for increasing symmetry energy direct URCA processes are allowed in the almost whole density range where the kaon condensation exists.

  18. Kaon condensates, nuclear symmetry energy and cooling of neutron stars

    International Nuclear Information System (INIS)

    Kubis, S.; Kutschera, M.

    2003-01-01

    The cooling of neutron stars by URCA processes in the kaon-condensed neutron star matter for various forms of nuclear symmetry energy is investigated. The kaon-nucleon interactions are described by a chiral Lagrangian. Nuclear matter energy is parametrized in terms of the isoscalar contribution and the nuclear symmetry energy in the isovector sector. High density behaviour of nuclear symmetry energy plays an essential role in determining the composition of the kaon-condensed neutron star matter which in turn affects the cooling properties. We find that the symmetry energy which decreases at higher densities makes the kaon-condensed neutron star matter fully protonized. This effect inhibits strongly direct URCA processes resulting in slower cooling of neutron stars as only kaon-induced URCA cycles are present. In contrast, for increasing symmetry energy direct URCA processes are allowed in the almost whole density range where the kaon condensation exists

  19. Monte Carlo calculations of neutron and gamm-ray energy spectra for fusion-reactor shield design: comparison with experiment

    International Nuclear Information System (INIS)

    Santoro, R.T.; Barnes, J.M.

    1983-08-01

    Neutron and gamma-ray spectra resulting from the interactions of approx. 14-MeV neutrons in laminated slabs of stainless steel type-304 and borated polyethylene have been calculated using the Monte Carlo code MCNP. The calculated spectra are compared with measured data as a function of slab thickness and material composition and as a function of detector location behind the slabs. Comparisons of the differential energy spectra are made for neutrons with energies above 850 keV and for gamma rays with energies above 750 keV. The measured neutron spectra and those calculated using Monte Carlo methods agree within 5% to 50% depending on the slab thickness and composition and neutron energy. The agreement between the measured and calculated gamma-ray energy spectra is also within this range. The MCNP data are also in favorable agreement with attenuated data calculated previously by discrete ordinates transport methods and the Monte Carlo code SAM-CE

  20. Neutron scattering cross sections for 204,206Pb and neutron and proton amplitudes of E2 and E3 excitations

    International Nuclear Information System (INIS)

    Hicks, S.F.; Hanly, J.M.; Hicks, S.E.; Shen, G.R.; McEllistrem, M.T.

    1994-01-01

    Differential elastic and inelastic scattering cross sections have been measured for neutrons incident on 204 Pb and 206 Pb at energies of 2.5, 4.6, and 8.0 MeV and total cross sections in 100-keV steps from 250 keV to 4.0 MeV. Both spherical and coupled-channels analyses have been used to interpret this large set of data, together with other cross sections extending to 8 MeV. Several purposes motivate this work. The first is to establish the dispersion-corrected mean field appropriate for these nuclei. A consistent description of the energy dependent neutron scattering potential includes a dispersion relation connecting the real and imaginary parts of the potential; the resultant potential relates the energy dependent scattering field to one representing bound single particle levels. Dispersion relations using both the single channel and coupled-channels models have been examined; both give very similar results. The second motivation is to deduce neutron and proton excitation strengths of the lowest-energy quadrupole and octupole excitations seen via neutron scattering, and to compare those strengths with similar values derived from electromagnetic exciton, heavy-ion and pion scattering. The role of target neutrons in both collective excitations was found to be enhanced compared to the proton role

  1. The spherical limit of the n-vector model and correlation inequaljties

    International Nuclear Information System (INIS)

    Angelescu, N.; Bundaru, M.; Costache, G.

    1978-08-01

    The asymptotics of the state of the n-vector model with a finite number of spins in the spherical limit is studied. Besides rederiving the limit free energy, corresponding to a generalized spherical model (with ''spherical constraint'' at every site), we obtain also the limit of the correlation functions, which allow a precise definition of the state of the latter model. Correlation inequalities are proved for ferromagnetic interactions in the asymptotic regime. In particular, it is shown that the generalized spherical model fulfills the expected Griffiths' type inequalities, differing in this respect from the spherical model with overall constraint. (author)

  2. Parallelization of a spherical Sn transport theory algorithm

    International Nuclear Information System (INIS)

    Haghighat, A.

    1989-01-01

    The work described in this paper derives a parallel algorithm for an R-dependent spherical S N transport theory algorithm and studies its performance by testing different sample problems. The S N transport method is one of the most accurate techniques used to solve the linear Boltzmann equation. Several studies have been done on the vectorization of the S N algorithms; however, very few studies have been performed on the parallelization of this algorithm. Weinke and Hommoto have looked at the parallel processing of the different energy groups, and Azmy recently studied the parallel processing of the inner iterations of an X-Y S N nodal transport theory method. Both studies have reported very encouraging results, which have prompted us to look at the parallel processing of an R-dependent S N spherical geometry algorithm. This geometry was chosen because, in spite of its simplicity, it contains the complications of the curvilinear geometries (i.e., redistribution of neutrons over the discretized angular bins)

  3. Exact solution of equations for proton localization in neutron star matter

    Science.gov (United States)

    Kubis, Sebastian; Wójcik, Włodzimierz

    2015-11-01

    The rigorous treatment of proton localization phenomenon in asymmetric nuclear matter is presented. The solution of proton wave function and neutron background distribution is found by the use of the extended Thomas-Fermi approach. The minimum of energy is obtained in the Wigner-Seitz approximation of a spherically symmetric cell. The analysis of four different nuclear models suggests that the proton localization is likely to take place in the interior of a neutron star.

  4. Neutron multiplicity for neutron induced fission of 235U, 238U, and 239Pu as a function of neutron energy

    International Nuclear Information System (INIS)

    Zucker, M.S.; Holden, N.E.

    1986-01-01

    Recent development in the theory and practice of neutron correlation (''coincidence'') counting require knowledge of the higher factorial moments of the P/sub ν/ distribution (the probability that (ν) neutrons are emitted in a fission) for the case where the fission is induced by bombarding neutrons of more than thermal energies. In contrast to the situation with spontaneous and thermal neutron induced fission, where with a few exceptions the P/sub ν/ is reasonably well known, in the fast neutron energy region, almost no information is available concerning the multiplicity beyond the average value, [ν], even for the most important nuclides. The reason for this is the difficulty of such experiments, with consequent statistically poor and physically inconsistent results

  5. Scoping studies - photon and low energy neutron interrogation

    Energy Technology Data Exchange (ETDEWEB)

    Becker, G.; Harker, Y.; Jones, J. [LMITCo, Idaho Falls, ID (United States); Harmon, F. [Idaho State Univ., Pocatello, ID (United States)

    1997-11-01

    High energy photon interrogation of waste containers, with the aim of producing photo nuclear reactions, in specific materials, holds the potential of good penetration and rapid analysis. Compact high energy ({le} 10 MeV) photon sources in the form of electron linacs producing bremstrahlung radiation are readily available. Work with the Varitron variable energy accelerator at ISU will be described. Advantages and limitations of the technique will be discussed. Using positive ion induced neutron producing reactions, it is possible to generate neutrons in a specific energy range. By this means, variable penetration and specific reactions can be excited in the assayed material. Examples using the {sup 3}H(p,n) and {sup 7}Li(p,n) reactions as neutron sources will be discussed. 4 refs., 7 figs.

  6. Intermediate-energy neutron beam for NCT at MURR

    International Nuclear Information System (INIS)

    Brugger, R.M.; Less, T.J.; Passmore, G.G.

    1986-01-01

    The University of Missouri Research Reactor (MURR) is one of the high-flux reactors in the USA and it can be used to produce an intense beam of intermediate-energy neutrons for neutron capture therapy. Two methods are being evaluated at MURR to produce such a beam. The first uses a moderator of Al 2 O 3 replacing part of the graphite and water on one side of the core of the reactor to produce a source of predominantly intermediate-energy neutrons. The second method is a filter of 238 U between the core and the patient position to pass only intermediate-energy neutrons. The results of these evaluations are presented in this paper along with an outline of the other resources at the University of Missouri-Columbia that are available to support an NCT program. 4 references, 7 figures, 1 table

  7. Spherical, rolling magnet generators for passive energy harvesting from human motion

    Science.gov (United States)

    Bowers, Benjamin J.; Arnold, David P.

    2009-09-01

    In this work, non-resonant, vibrational energy harvester architectures intended for human-motion energy scavenging are researched. The basic design employs a spherical, unidirectionally magnetized permanent magnet (NdFeB) ball that is allowed to move arbitrarily in a spherical cavity wrapped with copper coil windings. As the ball rotates and translates within the cage, the time-varying magnetic flux induces a voltage in the coil according to Faraday's Law. Devices ranging from 1.5 cm3 to 4 cm3 in size were tested under human activity scenarios—held in the user's hand or placed in the user's pocket while walking (4 km h-1) and running (14.5 km h-1). These harvesters have demonstrated rms voltages ranging from ~80 mV to 700 mV and time-averaged power densities up to 0.5 mW cm-3.

  8. Theoretical investigation of stark effect on shallow donor binding energy in InGaN spherical QD-QW

    International Nuclear Information System (INIS)

    El Ghazi, Haddou; Jorio, Anouar; Zorkani, Izeddine

    2013-01-01

    In this paper, a simultaneous study of electric field and impurity's position effects on the ground-state shallow-donor binding energy in GaN|InGaN|GaN spherical quantum dot-quantum well (SQD-QW) as a function of the ratio of the inner and the outer radius is reported. The calculations are investigated using variational approach within the framework of the effective-mass approximation. The numerical results show that: (i) the binding energy is strongly affected by the external electric field and the SQD-QW dimension, (ii) a critical value of spherical system's radius is obtained constituting the limit of three dimension confinement and spherical thin layer confinement and (iii) the Stark shift increases with increasing electric field and it is more pronounced around the position of the impurity corresponding to the binding energy maxima than in the spherical layer extremities

  9. A study of dissipative phenomena using Orion, a 4 π sectorized neutron detector

    International Nuclear Information System (INIS)

    Galin, J.; Guerreau, D.; Morjean, M.; Pouthas, J.; Saint-Laurent, F.; Sokolov, A.; Wang, X.M.; Piasecki, E.; Charvet, J.L.; CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette

    1990-01-01

    When studying the behavior of hot nuclei, the challenge is twofold: how are they formed in nucleus-nucleus collisions and how do they decay. For heavy and, thus neutron rich systems a large fraction of the thermalized energy is evacuated by neutron evaporation. Therefore the numbering, event-wise, of neutrons, over 4 π, gives a strong handle on energy dissipation for the different reaction channels. The first neutron measurements of this kind were performed using spherical detectors made of two hemispheres. Since then, a new and larger 4 π detector, ORION, has been designed in order to get information on the spatial distribution of the neutrons. The main characteristics of ORION are described and a few examples are given in order to illustrate the capabilities of such a detector in the study of dissipative collisions

  10. Reactor-moderated intermediate-energy neutron beams for neutron-capture therapy

    International Nuclear Information System (INIS)

    Less, T.J.

    1987-01-01

    One approach to producing an intermediate energy beam is moderating fission neutrons escaping from a reactor core. The objective of this research is to evaluate materials that might produce an intermediate beam for NCT via moderation of fission neutrons. A second objective is to use the more promising moderator material in a preliminary design of an NCT facility at a research reactor. The evaluations showed that several materials or combinations of materials could produce a moderator source for an intermediate beam for NCT. The best neutron spectrum for use in NCT is produced by Al 2 O 3 , but mixtures of Al metal and D 2 O are also attractive. Using the best moderator materials, results were applied to the design of an NCT moderator at the Georgia Institute of Technology Research Reactor's bio-medical facility. The amount of photon shielding and thermal neutron absorber were optimized with respect to the desired photon dose rate and intermediate neutron flux at the patient position

  11. Energy dependence of relative abundances and periods of separate groups of delayed neutrons at neutron induced fission of 239Pu in a range of neutrons energies 0.37 - 5 MeV

    International Nuclear Information System (INIS)

    Roschenko, V.A.; Piksaikin, V.M.; Kazakov, L.E.; Isaev, S.G.; Korolev, G.G.; Tarasko, M.Z.; Tertychnyi, R.G.

    2001-01-01

    The fundamental role of delayed neutrons in behavior, control and safety of reactors is well known today. Delayed neutron data are of great interest not only for reactor physics but also for nuclear fission physics and astrophysics. The purpose of the present work was the measurement of energy dependence of delayed neutrons (DN) group parameters at fission of nuclei 239 Pu in a range of energies of primary neutrons from 0.37 up to 5 MeV. The measurements were executed on installation designed on the basis of the electrostatic accelerator of KG - 2.5 SSC RF IPPE. The data are obtained in 6-group representation. It is shown, that there is a significant energy dependence of DN group parameters in a range of primary neutrons energies from thermal meanings up to 5 MeV, which is expressed in reduction of the average half-life of nuclei of the DN precursors on 10 %. The data, received in the present work, can be used at creation of a set of group constants for reactors with an intermediate spectrum of neutrons. (authors)

  12. Shape transition in the neutron rich sodium isotopes

    International Nuclear Information System (INIS)

    Campi, X.; Flocard, H.; Kerman, A.K.; Koonin, S.; Massachusetts Inst. of Tech., Cambridge

    1975-06-01

    Mass spectrometer measurements of the neutron rich sodium isotopes show a sudden increase at 31 Na in the values of the two neutron separation energies. The spherical shell model naturally predicts a sudden decrease at 32 Na after the N=20 shell closure. It is proposed that the explanation for this disagreement lies in the fact that sodium isotopes in this mass region are strongly deformed due to the filling of negative parity orbitals from the 1fsub(7/2) shell. Hartree-Fock calculations are presented in support of this conjecture [fr

  13. Spherical sila- and germa-homoaromaticity.

    Science.gov (United States)

    Chen, Zhongfang; Hirsch, Andreas; Nagase, Shigeru; Thiel, Walter; Schleyer, Paul von Ragué

    2003-12-17

    Guided by the 2(N + 1)2 electron-counting rule for spherical aromatic molecules, we have designed various spherical sila- and germa-homoaromatic systems rich in group 14 elements. Their aromaticity is revealed by density-functional computations of their structures and the nucleus-independent chemical shifts (NICS). Besides the formerly used endohedral inclusion strategy, spherical homoaromaticity is another way to stabilize silicon and germanium clusters.

  14. Recent research on nuclear reaction using high-energy proton and neutron

    Energy Technology Data Exchange (ETDEWEB)

    Shibata, Tokushi [Tokyo Univ., Tanashi (Japan). Inst. for Nuclear Study

    1997-11-01

    The presently available high-energy neutron beam facilities are introduced. Then some interesting research on nuclear reaction using high-energy protons are reported such as the intermediate mass fragments emission and neutron spectrum measurements on various targets. As the important research using high-energy neutron, the (p,n) reactions on Mn, Fe, and Ni, the elastic scattering of neutrons, and the shielding experiments are discussed. (author)

  15. Independent yields of Rb and Cs isotopes from thermal-neutron induced fission of 235U

    International Nuclear Information System (INIS)

    Balestrini, S.J.; Decker, R.; Wollnik, H.; Wuensch, K.D.; Jung, G.; Koglin, E.; Siegert, G.

    1979-01-01

    The relative yields of Rb and Cs isotopes from thermal-neutron fission of 235 U have been redetermined using the mass separator OSTIS, on-line at a neutron guide of the High-Flux Beam Reactor at the Institut Laue-Langevin, Grenoble, France. The separator ion source was a hot oven containing 235 U in a graphite matrix. The neutron beam was pulsed. Alkali fission products diffused out of the graphite and were ionized, thus producing a stepwise increase in the analyzed ion beam proportional to the independent fission yield. The ion beam and the fissions in the source were monitored simultaneously. The diffusion of Rb and Cs from the source was exponential in time with half-lives ranging from 2.8 to 18 sec, depending upon the element and source temperature. The independent fission yields of Rb and Cs are normalized by equating their element yields to each other and to a value computed from the charge distributions observed with the recoil separator LOHENGRIN and well established mass yields. Fractional independent yields are deduced from the independent fission yields, and these compare very well with the EOZ model described by Wahl

  16. Portable instrument for measuring neutron energy spectra and neutron dose in a mixed n-γ field

    International Nuclear Information System (INIS)

    Daniels, C. J.; Silberberg, J. L.

    1980-01-01

    A portable high-speed neutron spectrometer consists of an organic scintillator, a true zero-crossing pulse shape discriminator, a 1 MHZ conversion-rate multichannel analyzer, an 8-bit microcomputer, and appropriate displays. The device can be used to measure neutron energy spectra and kerma rate in intense n- gamma radiation fields in which the neutron energy is from 5 to 15 MEV

  17. Spherical Casimir pistons

    Energy Technology Data Exchange (ETDEWEB)

    Dowker, J S, E-mail: dowker@man.ac.uk [Theory Group, School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom)

    2011-08-07

    A piston is introduced into a spherical lune Casimir cavity turning it into two adjacent lunes separated by the (hemispherical) piston. On the basis of zeta-function regularization, the vacuum energy of the arrangement is finite for conformal propagation in spacetime. For even spheres this energy is independent of the angle of the lune. For odd dimensions it is shown that for all Neumann, or all Dirichlet, boundary conditions the piston is repelled or attracted by the nearest wall if d = 3, 7, ... or if d = 1, 5, ... , respectively. For hybrid N-D conditions these requirements are switched. If a mass is added, divergences arise which render the model suspect. The analysis, however, is relatively straightforward and involves the Barnes zeta function. The extension to finite temperatures is made and it is shown that for the 3, 7, ... series of odd spheres, the repulsion by the walls continues but that, above a certain temperature, the free energy acquires two minima symmetrically placed about the midpoint.

  18. Spherical Casimir pistons

    International Nuclear Information System (INIS)

    Dowker, J S

    2011-01-01

    A piston is introduced into a spherical lune Casimir cavity turning it into two adjacent lunes separated by the (hemispherical) piston. On the basis of zeta-function regularization, the vacuum energy of the arrangement is finite for conformal propagation in spacetime. For even spheres this energy is independent of the angle of the lune. For odd dimensions it is shown that for all Neumann, or all Dirichlet, boundary conditions the piston is repelled or attracted by the nearest wall if d = 3, 7, ... or if d = 1, 5, ... , respectively. For hybrid N-D conditions these requirements are switched. If a mass is added, divergences arise which render the model suspect. The analysis, however, is relatively straightforward and involves the Barnes zeta function. The extension to finite temperatures is made and it is shown that for the 3, 7, ... series of odd spheres, the repulsion by the walls continues but that, above a certain temperature, the free energy acquires two minima symmetrically placed about the midpoint.

  19. Theoretical investigation of stark effect on shallow donor binding energy in InGaN spherical QD-QW

    Energy Technology Data Exchange (ETDEWEB)

    El Ghazi, Haddou, E-mail: hadghazi@gmail.com [Solid State Physics Laboratory, Faculty of Science, Dhar EL Mehrez, BP 1796 Fes-Atlas (Morocco); Mathématiques spéciales, CPGE Kénitra, Chakib Arsalane Street (Morocco); Jorio, Anouar; Zorkani, Izeddine [Solid State Physics Laboratory, Faculty of Science, Dhar EL Mehrez, BP 1796 Fes-Atlas (Morocco)

    2013-08-01

    In this paper, a simultaneous study of electric field and impurity's position effects on the ground-state shallow-donor binding energy in GaN|InGaN|GaN spherical quantum dot-quantum well (SQD-QW) as a function of the ratio of the inner and the outer radius is reported. The calculations are investigated using variational approach within the framework of the effective-mass approximation. The numerical results show that: (i) the binding energy is strongly affected by the external electric field and the SQD-QW dimension, (ii) a critical value of spherical system's radius is obtained constituting the limit of three dimension confinement and spherical thin layer confinement and (iii) the Stark shift increases with increasing electric field and it is more pronounced around the position of the impurity corresponding to the binding energy maxima than in the spherical layer extremities.

  20. Burnup-dependent core neutronics analysis of plate-type research reactor using deterministic and stochastic methods

    International Nuclear Information System (INIS)

    Liu, Shichang; Wang, Guanbo; Liang, Jingang; Wu, Gaochen; Wang, Kan

    2015-01-01

    Highlights: • DRAGON & DONJON were applied in burnup calculations of plate-type research reactors. • Continuous-energy Monte Carlo burnup calculations by RMC were chosen as references. • Comparisons of keff, isotopic densities and power distribution were performed. • Reasons leading to discrepancies between two different approaches were analyzed. • DRAGON & DONJON is capable of burnup calculations with appropriate treatments. - Abstract: The burnup-dependent core neutronics analysis of the plate-type research reactors such as JRR-3M poses a challenge for traditional neutronics calculational tools and schemes for power reactors, due to the characteristics of complex geometry, highly heterogeneity, large leakage and the particular neutron spectrum of the research reactors. Two different theoretical approaches, the deterministic and the stochastic methods, are used for the burnup-dependent core neutronics analysis of the JRR-3M plate-type research reactor in this paper. For the deterministic method the neutronics codes DRAGON & DONJON are used, while the continuous-energy Monte Carlo code RMC (Reactor Monte Carlo code) is employed for the stochastic one. In the first stage, the homogenizations of few-group cross sections by DRAGON and the full core diffusion calculations by DONJON have been verified by comparing with the detailed Monte Carlo simulations. In the second stage, the burnup-dependent calculations of both assembly level and the full core level were carried out, to examine the capability of the deterministic code system DRAGON & DONJON to reliably simulate the burnup-dependent behavior of research reactors. The results indicate that both RMC and DRAGON & DONJON code system are capable of burnup-dependent neutronics analysis of research reactors, provided that appropriate treatments are applied in both assembly and core levels for the deterministic codes

  1. Neutrons and antimony physical measurements and interpretations

    International Nuclear Information System (INIS)

    Smith, A. B.

    2000-01-01

    New experimental information for the elastic and inelastic scattering of ∼ 4--10 MeV neutrons from elemental antimony is presented. The differential measurements are made at ∼ 40 or more scattering angles and at incident neutron-energy intervals of ∼ 0.5 MeV. The present experimental results, those previously reported from this laboratory and as found in the literature are comprehensively interpreted using spherical optical-statistical and dispersive-optical models. Direct vibrational processes via core-excitation, isospin and shell effects are discussed. Antimony models for applications are proposed and compared with global, regional, and specific models reported in the literature

  2. Method for controlling an accelerator-type neutron source, and a pulsed neutron source

    International Nuclear Information System (INIS)

    Givens, W.W.

    1991-01-01

    The patent deals with an accelerator-type neutron source which employs a target, an ionization section and a replenisher for supplying accelerator gas. A positive voltage pulse is applied to the ionization section to produce a burst of neutrons. A negative voltage pulse is applied to the ionization section upon the termination of the positive voltage pulse to effect a sharp cut-off to the burst of neutrons. 4 figs

  3. Calculation of neutron and gamma ray energy spectra for fusion reactor shield design: comparison with experiment

    International Nuclear Information System (INIS)

    Santoro, R.T.; Alsmiller, R.G. Jr.; Barnes, J.M.; Chapman, G.T.

    1980-08-01

    Integral experiments that measure the transport of approx. 14 MeV D-T neutrons through laminated slabs of proposed fusion reactor shield materials have been carried out. Measured and calculated neutron and gamma ray energy spectra are compared as a function of the thickness and composition of stainless steel type 304, borated polyethylene, and Hevimet (a tungsten alloy), and as a function of detector position behind these materials. The measured data were obtained using a NE-213 liquid scintillator using pulse-shape discrimination methods to resolve neutron and gamma ray pulse height data and spectral unfolding methods to convert these data to energy spectra. The calculated data were obtained using two-dimensional discrete ordinates radiation transport methods in a complex calculational network that takes into account the energy-angle dependence of the D-T neutrons and the nonphysical anomalies of the S/sub n/ method

  4. Polarized Neutron Scattering

    OpenAIRE

    Roessli, B.; Böni, P.

    2000-01-01

    The technique of polarized neutron scattering is reviewed with emphasis on applications. Many examples of the usefulness of the method in various fields of physics are given like the determination of spin density maps, measurement of complex magnetic structures with spherical neutron polarimetry, inelastic neutron scattering and separation of coherent and incoherent scattering with help of the generalized XYZ method.

  5. Fast neutron relaxation length in concretes in the range of neutron energies En=0.5 - 17.5 MeV

    International Nuclear Information System (INIS)

    Desdin, L.F.; Garcia, L.; Perez, G.; Hernandez, A.; Herrera, E.; Tellez, E.

    1998-01-01

    In the present research were determined the fast neutron relaxation length y in different type of concretes, having special interest for biological shielding as well as for ordinary construction purposes, in the energy interval of 0.5-17.5 MeV. The values of Y concrete are reported with an accuracy of 6 %

  6. Shape coexistence in the neutron-deficient Pt isotopes in a configuration mixing IBM

    International Nuclear Information System (INIS)

    Morales, Irving O.; Vargas, Carlos E.; Frank, Alejandro

    2004-01-01

    The recently proposed matrix-coherent state approach for configuration mixing IBM is used to describe the evolving geometry of the neutron deficient Pt isotopes. It is found that the Potential Energy Surface (PES) of the Platinum isotopes evolves, when the number of neutrons decreases, from spherical to oblate and then to prolate shapes, in agreement with experimental measurements. Oblate-Prolate shape coexistence is observed in 194,192Pt isotopes

  7. The neutronic design and performance of the Indiana University Cyclotron Facility (IUCF) Low Energy Neutron Source (LENS)

    Science.gov (United States)

    Lavelle, Christopher M.

    Neutron scattering research is performed primarily at large-scale facilities. However, history has shown that smaller scale neutron scattering facilities can play a useful role in education and innovation while performing valuable materials research. This dissertation details the design and experimental validation of the LENS TMR as an example for a small scale accelerator driven neutron source. LENS achieves competitive long wavelength neutron intensities by employing a novel long pulse mode of operation, where the neutron production target is irradiated on a time scale comparable to the emission time of neutrons from the system. Monte Carlo methods have been employed to develop a design for optimal production of long wavelength neutrons from the 9Be(p,n) reaction at proton energies ranging from 7 to 13 MeV proton energy. The neutron spectrum was experimentally measured using time of flight, where it is found that the impact of the long pulse mode on energy resolution can be eliminated at sub-eV neutron energies if the emission time distribution of neutron from the system is known. The emission time distribution from the TMR system is measured using a time focussed crystal analyzer. Emission time of the fundamental cold neutron mode is found to be consistent with Monte Carlo results. The measured thermal neutron spectrum from the water reflector is found to be in agreement with Monte Carlo predictions if the scattering kernels employed are well established. It was found that the scattering kernels currently employed for cryogenic methane are inadequate for accurate prediction of the cold neutron intensity from the system. The TMR and neutronic modeling have been well characterized and the source design is flexible, such that it is possible for LENS to serve as an effective test bed for future work in neutronic development. Suggestions for improvements to the design that would allow increased neutron flux into the instruments are provided.

  8. Cold neutron source conceptual designing for Tehran Research Reactor

    International Nuclear Information System (INIS)

    Khajvand, N.; Mirvakili, S.M.; Faghihi, F.

    2016-01-01

    Highlights: • Cold neutron source conceptual designing for Tehran research reactor is carried out. • Type and geometry of moderator and dimensions of cold neutron source are analyzed. • Liquid hydrogen with more ortho-concentration can be better option as moderator. - Abstract: A cold neutron source (CNS) conceptual designing for the Tehran Research Reactor (TRR) were carried out using MCNPX code. In this study, a horizontal beam tube of the core which has appropriate the highest thermal flux is selected and parametric analysis to choose the type and geometry of the moderator, and the required CNS dimensions for maximizing the cold neutron production was performed. In this design the moderator cell has a spherical annulus structure, and the cold neutron flux and its brightness are calculated together with the nuclear heat load of the CNS for a variety of materials including liquid hydrogen, liquid deuterium, and solid methane. Based on our study, liquid hydrogen with more ortho-concentration than para and solid methane are the best options.

  9. Statistical properties of warm nuclei: Investigating the low-energy enhancement in the $\\gamma$- strength function of neutron-rich nuclei

    CERN Multimedia

    We propose to start a program to study the $\\gamma$-ray strength function of neutron rich nuclei in inverse kinematics with radioactive beams at HIE-ISOLDE. An unexpected increase in the $\\gamma$-strength function at low energy has been observed in several stable nuclei using the Oslo method. This year these results were confirmed with a different experimental technique and model independent analysis developed by iThemba/Livermore. If this enhancement of the $\\gamma$-strength function is also present in neutron-rich nuclei, it will strongly affect the neutron capture cross sections, which are important input in stellar models of synthesis of heavier elements in stars. We propose to start with an experiment using a $^{66}$Ni beam of 5.5 MeV /u, where the data will be analyzed using both methods independently, and we are sure to get enough statistics, before moving to more neutron-rich nuclei. When/if neutron-rich Ti, Fe or Mo beams will be available at ISOLDE, we will submit additional proposals.

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

    International Nuclear Information System (INIS)

    Rossa, Riccardo; Borella, Alessandro; Labeau, Pierre-Etienne; Pauly, Nicolas; Meer, Klaas van der

    2015-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-11

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

  12. Unified description of astrophysical properties of neutron stars independent of the equation of state

    Science.gov (United States)

    Pappas, George

    2015-12-01

    In recent years, a lot of work was done that has revealed some very interesting properties of neutron stars. One can relate the first few multipole moments of a neutron star, or quantities that can be derived from them, with relations that are independent of the equation of state (EoS). This is a very significant result that has great implications for the description of neutron stars and in particular for the description of the spacetime around them. Additionally, it was recently shown that there is a four-parameter analytic spacetime, known as the two-soliton spacetime, which can accurately capture the properties of the geometry around neutron stars. This allows for the possibility of describing in a unified formalism the astrophysically relevant properties of the spacetime around a neutron star independently of the particulars of the EoS for the matter of the star. More precisely, the description of these astrophysical properties is done using an EoS omniscient spacetime that can describe the exterior of any neutron star. In the present work, we investigate properties such as the location of the innermost stable circular orbit RISCO (or the surface of the star when the latter overcomes the former), the various frequencies of perturbed circular equatorial geodesics, the efficiency of an accretion disc, its temperature distribution, and other properties associated with the emitted radiation from the disc, in a way that holds for all possible choices of a realistic EoS for the neutron star. Furthermore, we provide proof of principle that if one were to measure the right combinations of pairs of these properties, with the additional knowledge of the mass of the neutron star, one could determine the EoS of the star.

  13. Feasibility of the Precise Energy Calibration for Fast Neutron Spectrometers

    Science.gov (United States)

    Gaganov, V. V.; Usenko, P. L.; Kryzhanovskaja, M. A.

    2017-12-01

    Computational studies aimed at improving the accuracy of measurements performed using neutron generators with a tritium target were performed. A measurement design yielding an extremely narrow peak in the energy spectrum of DT neutrons was found. The presence of such a peak establishes the conditions for precise energy calibration of fast-neutron spectrometers.

  14. Neutronics comparative analysis of plate-type research reactor using deterministic and stochastic methods

    International Nuclear Information System (INIS)

    Liu, Shichang; Wang, Guanbo; Wu, Gaochen; Wang, Kan

    2015-01-01

    Highlights: • DRAGON and DONJON are applied and verified in calculations of research reactors. • Continuous-energy Monte Carlo calculations by RMC are chosen as the references. • “ECCO” option of DRAGON is suitable for the calculations of research reactors. • Manual modifications of cross-sections are not necessary with DRAGON and DONJON. • DRAGON and DONJON agree well with RMC if appropriate treatments are applied. - Abstract: Simulation of the behavior of the plate-type research reactors such as JRR-3M and CARR poses a challenge for traditional neutronics calculation tools and schemes for power reactors, due to the characteristics of complex geometry, highly heterogeneity and large leakage of the research reactors. Two different theoretical approaches, the deterministic and the stochastic methods, are used for the neutronics analysis of the JRR-3M plate-type research reactor in this paper. For the deterministic method the neutronics codes DRAGON and DONJON are used, while the continuous-energy Monte Carlo code RMC (Reactor Monte Carlo code) is employed for the stochastic approach. The goal of this research is to examine the capability of the deterministic code system DRAGON and DONJON to reliably simulate the research reactors. The results indicate that the DRAGON and DONJON code system agrees well with the continuous-energy Monte Carlo simulation on both k eff and flux distributions if the appropriate treatments (such as the ECCO option) are applied

  15. Dynamically polarized hydrogen target as a broadband, wavelength-independent thermal neutron spin polarizer

    International Nuclear Information System (INIS)

    Zhao Jinkui; Garamus, Vasil M.; Mueller, Wilhelm; Willumeit, Regine

    2005-01-01

    A hydrogen-rich sample with dynamically polarized hydrogen nuclei was tested as a wavelength-independent neutron transmission spin polarizer. The experiment used a modified setup of the dynamic nuclear polarization target station at the GKSS research center. The standard solvent sample at the GKSS DNP station was used. It is 2.8mm thick and consists of 43.4wt% water, 54.6wt% glycerol, and 2wt% of EHBA-Cr(v) complex. The wavelength of the incident neutrons for the transmission experiment was λ=8.1A with Δλ/λ=10%. The polarization of neutron beam after the target sample was analyzed with a supermirror analyzer. A neutron polarization of -52% was achieved at the hydrogen polarization of -69%. Further experiments will test the feasibility of other hydrogen-rich materials, such as methane, as the polarizer. A theoretical calculation shows that a polarized methane target would allow over 95% neutron polarizations with more than 30% transmission

  16. Studies of defects in neutron-irradiated p-type silicon by admittance measurements of n+-p diodes

    International Nuclear Information System (INIS)

    Tokuda, Y.; Usami, A.

    1978-01-01

    Defects introduced in p-type silicon by neutron irradiation were studied by measuring the admittance of n + -p diodes. It was shown that the energy levels and capture cross sections estimated from the temperature dependence of the admittance had some uncertainty due to the temperature dependence of the concentration of free carriers in the bulk and the high-frequency-junction capacitance. So, we presented the method of determination of the energy levels, capture cross sections, and concentrations of defects from the frequency dependence of the admittance. This method consists of the measurements of G/ω and C as a function of frequency. From this method, assuming that capture cross sections are independent of temperature, the energy levels of E/sub v/+0.16 and E/sub v/+0.36 eV were obtained. For these defects, the calculated values of the hole capture cross section were 2.4 x 10 -14 and 3.7 x 10 -14 cm 2 , respectively. Comparing with other published data, the energy level of E/sub v/+0.36 eV was found to be correlated with the divacancy

  17. Neutron and X-ray emission studies in a low energy plasma focus

    Energy Technology Data Exchange (ETDEWEB)

    Zakaullah, M. [Quaid-i-Azam Univ., Islamabad (Pakistan). Dept. of Physics; Murtaza, G. [Quaid-i-Azam Univ., Islamabad (Pakistan). Dept. of Physics; Qamar, S. [Quaid-i-Azam Univ., Islamabad (Pakistan). Dept. of Physics; Ahmad, I. [Quaid-i-Azam Univ., Islamabad (Pakistan). Dept. of Physics; Beg, M.M. [Quaid-i-Azam Univ., Islamabad (Pakistan). Dept. of Physics

    1996-03-01

    In a low energy Mather-type plasma focus energized by a single 32 {mu}F capacitor, the X-ray and neutron emission is investigated using time-integrated and time-resolved detectors. The X-ray emission profile has a width (FWHM) of 40-50 ns. The neutron emission profile is broader compared to the X-ray emission profile and also delayed by 30-40 ns. To identify different regimes of X-ray emission, an X-ray pin-hole camera along with different absorption filters is employed. While the X-ray emission is high within a narrow pressure range of 2.0-2.5 mbar, the neutron emission is intense for a wider range of 1.0-4.5 mbar. The intense X-ray emission seems to originate from the axially moving shock wave. These results also indicate rather different production mechanisms for X-ray and neutron emission. Also on comparing the X-ray images with Al(2 {mu}m), Al(5 {mu}m), Al(9 {mu}m) filters, we find that the bulk of X-rays from the focus filament have energies less than 2 keV. (orig.).

  18. Polarimetric neutron scattering

    International Nuclear Information System (INIS)

    Tasset, F.

    2001-01-01

    Polarimetric Neutron Scattering in introduced, both by, explaining methodological issues and the corresponding instrumental developments. After a short overview of neutron spin polarization and the neutron polarization 3d-vector a pictorial approach of the microscopic theory is used to show how a polarized beam interacts with lattice and magnetic Fourier components in a crystal. Examples are given of using Spherical Neutron Polarimetry (SNP) and the corresponding Cryopad polarimeter for the investigation of non-collinear magnetic structures. (R.P.)

  19. Type II shell evolution in A=70 isobars from the N≥40 island of inversion

    Directory of Open Access Journals (Sweden)

    A.I. Morales

    2017-02-01

    Full Text Available The level structures of 70Co and 70Ni, populated from the β decay of 70Fe, have been investigated using β-delayed γ-ray spectroscopy following in-flight fission of a 238U beam. The experimental results are compared to Monte-Carlo Shell-Model calculations including the pf+g9/2+d5/2 orbitals. The strong population of a (1+ state at 274 keV in 70Co is at variance with the expected excitation energy of ∼1 MeV from near spherical single-particle estimates. This observation indicates a dominance of prolate-deformed intruder configurations in the low-lying levels, which coexist with the normal near spherical states. It is shown that the β decay of the neutron-rich A=70 isobars from the new island of inversion to the Z=28 closed-shell regime progresses in accordance with a newly reported type of shell evolution, the so-called Type II, which involves many particle-hole excitations across energy gaps.

  20. Characterization of Monoenergetic Low Energy Neutron Fields with the {mu}TPC Detector

    Energy Technology Data Exchange (ETDEWEB)

    Golabek, C.; Lebreton, L.; Petit, M. [Laboratoire de Metrologie et de Dosimetrie des Neutrons, IRSN Cadarache, 13115 Saint-Paul-Lez-Durance (France); Billard, J.; Grignon, C.; Bosson, G.; Bourrion, O.; Guillaudin, O.; Mayet, F.; Richer, J.-P.; Santos, D. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph (France)

    2011-12-13

    The AMANDE facility produces monoenergetic neutron fields from 2 keV to 20 MeV for metrological purposes. To be considered as a reference facility, fluence and energy distributions of neutron fields have to be determined by primary measurement standards. For this purpose, a micro Time Projection Chamber is being developed to be dedicated to measure neutron fields with energy ranging from 2 keV up to 1 MeV. We present simulations showing that such a detector, which allows the measurement of the ionization energy and the 3D reconstruction of the recoil nucleus, provides the determination of neutron energy and fluence of such low energy neutron fields.

  1. On three-dimensional incompressible Navier-Stokes fluid on cantor sets in spherical Cantor type co-ordinate system

    Directory of Open Access Journals (Sweden)

    Meng Zhi-Jun

    2016-01-01

    Full Text Available This paper addresses the systems of the incompressible Navier-Stokes equations on Cantor sets without the external force involving the fractal heat-conduction problem vial local fractional derivative. The spherical Cantor type co-ordinate method is used to transfer the incompressible Navier-Stokes equation from the Cantorian co-ordinate system into the spherical Cantor type co-ordinate system.

  2. Prompt neutron fission spectrum mean energies for the fissile nuclides and 252Cf

    International Nuclear Information System (INIS)

    Holden, N.E.

    1985-01-01

    The international standard for a neutron spectrum is that produced from the spontaneous fission of 252 Cf, while the thermal neutron induced fission neutron spectra for the four fissile nuclides, 233 U, 235 U, 239 Pu, and 241 Pu are of interest from the standpoint of nuclear reactors. The average neutron energies of these spectra are tabulated. The individual measurements are recorded with the neutron energy range measured, the method of detection as well as the average neutron energy for each author. Also tabulated are the measurements of the ratio of mean energies for pairs of fission neutron spectra. 75 refs., 9 tabs

  3. Energy dependence of fast neutron dosimetry using electrochemical etching

    International Nuclear Information System (INIS)

    Su, S.J.; Morgan, K.Z.

    1978-01-01

    Registration of fast-neutron induced recoil tracks by the electrochemical etching technique as applied to sensitive Lexan polycarbonate foils provides a simple and inexpensive means of fast neutron personnel dosimetry. The sensitivity (tracks/neutron) of recoil particle registration is given as a function of neutron energy. Neutrons of 7 Li (p,n) 7 Be, 3 T (d,n) 4 He and 9 B, respectively. Results are compared with other studies using other neutron sources and conventional etching method

  4. Analysis of incident-energy dependence of delayed neutron yields in actinides

    Energy Technology Data Exchange (ETDEWEB)

    Nasir, Mohamad Nasrun bin Mohd, E-mail: monasr211@gmail.com; Metorima, Kouhei, E-mail: kohei.m2420@hotmail.co.jp; Ohsawa, Takaaki, E-mail: ohsawa@mvg.biglobe.ne.jp; Hashimoto, Kengo, E-mail: kengoh@pp.iij4u.or.jp [Graduate School of Science and Engineering, Kindai University, Kowakae, Higashi-Osaka, 577-8502 (Japan)

    2015-04-29

    The changes of delayed neutron yields (ν{sub d}) of Actinides have been analyzed for incident energy up to 20MeV using realized data of precursor after prompt neutron emission, from semi-empirical model, and delayed neutron emission probability data (P{sub n}) to carry out a summation method. The evaluated nuclear data of the delayed neutron yields of actinide nuclides are still uncertain at the present and the cause of the energy dependence has not been fully understood. In this study, the fission yields of precursor were calculated considering the change of the fission fragment mass yield based on the superposition of fives Gaussian distribution; and the change of the prompt neutrons number associated with the incident energy dependence. Thus, the incident energy dependent behavior of delayed neutron was analyzed.The total number of delayed neutron is expressed as ν{sub d}=∑Y{sub i} • P{sub ni} in the summation method, where Y{sub i} is the mass yields of precursor i and P{sub ni} is the delayed neutron emission probability of precursor i. The value of Y{sub i} is derived from calculation of post neutron emission mass distribution using 5 Gaussian equations with the consideration of large distribution of the fission fragments. The prompt neutron emission ν{sub p} increases at higher incident-energy but there are two different models; one model says that the fission fragment mass dependence that prompt neutron emission increases uniformly regardless of the fission fragments mass; and the other says that the major increases occur at heavy fission fragments area. In this study, the changes of delayed neutron yields by the two models have been investigated.

  5. Continuous energy adjoint Monte Carlo for coupled neutron-photon transport

    Energy Technology Data Exchange (ETDEWEB)

    Hoogenboom, J.E. [Delft Univ. of Technology (Netherlands). Interfaculty Reactor Inst.

    2001-07-01

    Although the theory for adjoint Monte Carlo calculations with continuous energy treatment for neutrons as well as for photons is known, coupled neutron-photon transport problems present fundamental difficulties because of the discrete energies of the photons produced by neutron reactions. This problem was solved by forcing the energy of the adjoint photon to the required discrete value by an adjoint Compton scattering reaction or an adjoint pair production reaction. A mathematical derivation shows the exact procedures to follow for the generation of an adjoint neutron and its statistical weight. A numerical example demonstrates that correct detector responses are obtained compared to a standard forward Monte Carlo calculation. (orig.)

  6. Applications of the nuclear theory to the computation of neutron cross sections for actinide isotopes

    International Nuclear Information System (INIS)

    Konshin, V.A.

    1981-01-01

    Neutron cross section calculational methods for actinides in the unresolved resonance energy range (1-150 kev) are discussed, with a special emphasis on calculation of width fluctuation factors for the generalized distribution, as well as for a sub-threshold fission. It is shown that the energy dependence of sub(J), the (n,n') -process competition and the structure in neutron cross section has to be taken into account in the energy range considered. Analysis of different approaches in the statistical theory for heavy nuclei neutron cross-section calculation is given, and it is shown to be important to allow for the (n,γf)-reaction in neutron cross section calculations for fissile nuclei. The use of the non-spherical potential, the Lorentzian spectral factor and the Fermi-gas model involving the collective modes enables to obtain the self-consistent data for all neutron cross sections, including σnγ. (author)

  7. Energy dependence of relative abundances and periods of delayed neutron separate groups from neutron induced fission of 239Pu in the virgin neutron energy range 0.37-4.97 MeV

    International Nuclear Information System (INIS)

    Piksajkin, V.M.; Kazakov, L.E.; Isaev, S.T.; Korolev, G.G.; Roshchenko, V.A.; Tertychnyj, R.G.

    2002-01-01

    Relative yield and group period of delayed neutrons induced by the 239 Pu fission in the 0.37-4.97 MeV range were measured. Comparative analysis of experimental data was conducted in terms of middle period of half-life of delayed neutron nuclei-precursors. Character and scale of changing values of delayed neutron group parameters as changing excitation energy of fission compound-nucleus have been demonstrated for the first time. Considerable energy dependence of group parameters under the neutron induced 239 Pu fission that was expressed by the decreasing middle period of half-life of nuclei-precursors by 10 % in the 2.85 eV - 5 MeV range of virgin neutrons was detected [ru

  8. Neutron-photon multigroup cross sections for neutron energies up to 400 MeV: HILO86R

    International Nuclear Information System (INIS)

    Kotegawa, Hiroshi; Nakane, Yoshihiro; Hasegawa, Akira; Tanaka, Shun-ichi

    1993-02-01

    A macroscopic multigroup cross section library of 66 neutron and 22 photon groups for neutron energies up to 400 MeV: HILO86R is prepared for 10 typical shielding materials; water, concrete, iron, air, graphite, polyethylene, heavy concrete, lead, aluminum and soil. The library is a revision of the DLC-119/HILO86, in which only the cross sections below 19.6 MeV have been exchanged with a group cross section processed from the JENDL-3 microscopic cross section library. In the HILO86R library, self shielding factors are used to produce effective cross sections for neutrons less than 19.6 MeV considering rather coarse energy meshes. Energy spectra and dose attenuation in water, concrete and iron have been compared among the HILO, HILO86 and HILO86R libraries for different energy neutron sources. Significant discrepancy has been observed in the energy spectra less than a couple of MeV energy in iron among the libraries, resulting large difference in the dose attenuation. The difference was attributed to the effect of self-shielding factor, namely to the difference between infinite dilution and effective cross sections. Even for 400 MeV neutron source the influence of the self-shielding factor is significant, nevertheless only the cross sections below 19.6 MeV are exchanged. (author)

  9. Type-I superconductivity and neutron star precession

    International Nuclear Information System (INIS)

    Sedrakian, Armen

    2005-01-01

    Type-I proton superconducting cores of neutron stars break up in a magnetic field into alternating domains of superconducting and normal fluids. We examine two channels of superfluid-normal fluid friction where (i) rotational vortices are decoupled from the nonsuperconducting domains and the interaction is due to the strong force between protons and neutrons; (ii) the nonsuperconducting domains are dynamically coupled to the vortices and the vortex motion generates transverse electric fields within them, causing electronic current flow and Ohmic dissipation. The obtained dissipation coefficients are consistent with the Eulerian precession of neutron stars

  10. Experimental evaluation of the primary damage process: neutron energy effects

    Energy Technology Data Exchange (ETDEWEB)

    Goland, A.N.

    1979-01-01

    Experimental evaluation of the neutron energy dependnece of the primary damage stage depends upon a number of theoretical concepts. This state can only be observed after low- or perhaps ambient-temperature, low-fluence irradiations. The primary recoil energy spectrum, which determines the character of the displacement cascades, can be calculated if dosimetry has provided an accurate neutron spectrum. A review of experimental results relating neutron-energy effects shows that damage energy or damage energy cross section has often been a reliable correlation parameter for primary damage state experiments. However, the forthcoming emphasis on higher irradiation temperatures, more complex alloys and microstructural evolution has fostered a search for additional meaningful correlation parameters.

  11. Oncogenic transformation in C3H10T1/2 cells by low-energy neutrons.

    Science.gov (United States)

    Miller, R C; Marino, S A; Napoli, J; Shah, H; Hall, E J; Geard, C R; Brenner, D J

    2000-03-01

    Occupational exposure to neutrons typically includes significant doses of low-energy neutrons, with energies below 100 keV. In addition, the normal-tissue dose from boron neutron capture therapy will largely be from low-energy neutrons. Microdosimetric theory predicts decreasing biological effectiveness for neutrons with energies below about 350 keV compared with that for higher-energy neutrons; based on such considerations, and limited biological data, the current radiation weighting factor (quality factor) for neutrons with energies from 10 keV to 100 keV is less than that for higher-energy neutrons. By contrast, some reports have suggested that the biological effectiveness of low-energy neutrons is similar to that of fast neutrons. The purpose of the current work is to assess the relative biological effectiveness of low-energy neutrons for an endpoint of relevance to carcinogenesis: in vitro oncogenic transformation. Oncogenic transformation induction frequencies were determined for C3H10T1/2 cells exposed to two low-energy neutron beams, respectively, with dose-averaged energies of 40 and 70 keV, and the results were compared with those for higher-energy neutrons and X-rays. These results for oncogenic transformation provide evidence for a significant decrease in biological effectiveness for 40 keV neutrons compared with 350 keV neutrons. The 70 keV neutrons were intermediate in effectiveness between the 70 and 350 keV beams. A decrease in biological effectiveness for low-energy neutrons is in agreement with most (but not all) earlier biological studies, as well as microdosimetric considerations. The results for oncogenic transformation were consistent with the currently recommended decreased values for low-energy neutron radiation weighting factors compared with fast neutrons.

  12. Independent yields of Rb and Cs isotopes from thermal-neutron induced fission of /sup 235/U

    Energy Technology Data Exchange (ETDEWEB)

    Balestrini, S.J.; Decker, R.; Wollnik, H.; Wuensch, K.D.; Jung, G.; Koglin, E.; Siegert, G.

    1979-12-01

    The relative yields of Rb and Cs isotopes from thermal-neutron fission of /sup 235/U have been redetermined using the mass separator OSTIS, on-line at a neutron guide of the High-Flux Beam Reactor at the Institut Laue-Langevin, Grenoble, France. The separator ion source was a hot oven containing /sup 235/U in a graphite matrix. The neutron beam was pulsed. Alkali fission products diffused out of the graphite and were ionized, thus producing a stepwise increase in the analyzed ion beam proportional to the independent fission yield. The ion beam and the fissions in the source were monitored simultaneously. The diffusion of Rb and Cs from the source was exponential in time with half-lives ranging from 2.8 to 18 sec, depending upon the element and source temperature. The independent fission yields of Rb and Cs are normalized by equating their element yields to each other and to a value computed from the charge distributions observed with the recoil separator LOHENGRIN and well established mass yields. Fractional independent yields are deduced from the independent fission yields, and these compare very well with the EOZ model described by Wahl.

  13. D-D neutron energy-spectra measurements in Alcator C

    International Nuclear Information System (INIS)

    Pappas, D.S.; Wysocki, F.J.; Furnstahl, R.J.

    1982-08-01

    Measurements of energy spectra of neutrons produced during high density (anti n/sub e/ > 2 x 10 14 cm -3 ) deuterium discharges have been performed using a proton-recoil (NE 213) spectrometer. A two foot section of light pipe (coupling the scintillator and photomultiplier) was used to extend the scintillator into a diagnostic viewing port to maximize the neutron detection efficiency while not imposing excessive magnetic shielding requirements. A derivative unfolding technique was used to deduce the energy spectra. The results showed a well defined peak at 2.5 MeV which was consistent with earlier neutron flux measurements on Alcator C that indicated the neutrons were of thermonuclear origin

  14. Proton recoil spectra in spherical proportional counters calculated with finite element and Monte Carlo methods

    Energy Technology Data Exchange (ETDEWEB)

    Benmosbah, M. [Laboratoire de Chimie Physique et Rayonnement Alain Chambaudet, UMR CEA E4, Universite de Franche-Comte, 16 route de Gray, 25030 Besancon Cedex (France); Groetz, J.E. [Laboratoire de Chimie Physique et Rayonnement Alain Chambaudet, UMR CEA E4, Universite de Franche-Comte, 16 route de Gray, 25030 Besancon Cedex (France)], E-mail: jegroetz@univ-fcomte.fr; Crovisier, P. [Service de Protection contre les Rayonnements, CEA Valduc, 21120 Is/Tille (France); Asselineau, B. [Laboratoire de Metrologie et de Dosimetrie des Neutrons, IRSN, Cadarache BP3, 13115 St Paul-lez-Durance (France); Truffert, H.; Cadiou, A. [AREVA NC, Etablissement de la Hague, DQSSE/PR/E/D, 50444 Beaumont-Hague Cedex (France)

    2008-08-11

    Proton recoil spectra were calculated for various spherical proportional counters using Monte Carlo simulation combined with the finite element method. Electric field lines and strength were calculated by defining an appropriate mesh and solving the Laplace equation with the associated boundary conditions, taking into account the geometry of every counter. Thus, different regions were defined in the counter with various coefficients for the energy deposition in the Monte Carlo transport code MCNPX. Results from the calculations are in good agreement with measurements for three different gas pressures at various neutron energies.

  15. The energy-dependent backward-forward-isotropic scattering model with some applications to the neutron transport equation

    International Nuclear Information System (INIS)

    Williams, M.M.R.

    1985-01-01

    A multigroup formalism is developed for the backward-forward-isotropic scattering model of neutron transport. Some exact solutions are obtained in two-group theory for slab and spherical geometry. The results are useful for benchmark problems involving multigroup anisotropic scattering. (author)

  16. Neutron-neutron angular correlations in spontaneous fission of 252Cf and 240Pu

    Science.gov (United States)

    Verbeke, J. M.; Nakae, L. F.; Vogt, R.

    2018-04-01

    Background: Angular anisotropy has been observed between prompt neutrons emitted during the fission process. Such an anisotropy arises because the emitted neutrons are boosted along the direction of the parent fragment. Purpose: To measure the neutron-neutron angular correlations from the spontaneous fission of 252Cf and 240Pu oxide samples using a liquid scintillator array capable of pulse-shape discrimination. To compare these correlations to simulations combining the Monte Carlo radiation transport code MCNPX with the fission event generator FREYA. Method: Two different analysis methods were used to study the neutron-neutron correlations with varying energy thresholds. The first is based on setting a light output threshold while the second imposes a time-of-flight cutoff. The second method has the advantage of being truly detector independent. Results: The neutron-neutron correlation modeled by FREYA depends strongly on the sharing of the excitation energy between the two fragments. The measured asymmetry enabled us to adjust the FREYA parameter x in 240Pu, which controls the energy partition between the fragments and is so far inaccessible in other measurements. The 240Pu data in this analysis was the first available to quantify the energy partition for this isotope. The agreement between data and simulation is overall very good for 252Cf(sf ) and 240Pu(sf ) . Conclusions: The asymmetry in the measured neutron-neutron angular distributions can be predicted by FREYA. The shape of the correlation function depends on how the excitation energy is partitioned between the two fission fragments. Experimental data suggest that the lighter fragment is disproportionately excited.

  17. Polarizability and binding energy of a shallow donor in spherical quantum dot-quantum well (QD-QW)

    Science.gov (United States)

    Rahmani, K.; Chrafih, Y.; M’Zred, S.; Janati, S.; Zorkani, I.; Jorio, A.; Mmadi, A.

    2018-03-01

    The polarizability and the binding energy is estimated for a shallow donor confined to move in inhomogeneous quantum dots (CdS/HgS/CdS). In this work, the Hass variational method within the effective mass approximation in used in the case of an infinitely deep well. The polarizability and the binding energy depend on the inner and the outer radius of the QDQW, also it depends strongly on the donor position. It’s found that the stark effect is more important when the impurity is located at the center of the (QDQW) and becomes less important when the donor moves toward the extremities of the spherical layer. When the electric field increases, the binding energy and the polarizability decreases. Its effects is more pronounced when the impurity is placed on the center of the spherical layer and decrease when the donor move toward extremities of this spherical layer. We have demonstrated the existence of a critical value {≤ft( {{{{R_1}} \\over {{R_2}}}} \\right)cri} which can be used to distinguish the tree dimension confinement from the spherical surface confinement and it’s may be important for the nanofabrication techniques.

  18. Experimental determination of one- and two-neutron separation energies for neutron-rich copper isotopes

    Science.gov (United States)

    Yu, Mian; Wei, Hui-Ling; Song, Yi-Dan; Ma, Chun-Wang

    2017-09-01

    A method is proposed to determine the one-neutron S n or two-neutron S 2n separation energy of neutron-rich isotopes. Relationships between S n (S 2n) and isotopic cross sections have been deduced from an empirical formula, i.e., the cross section of an isotope exponentially depends on the average binding energy per nucleon B/A. The proposed relationships have been verified using the neutron-rich copper isotopes measured in the 64A MeV 86Kr + 9Be reaction. S n, S 2n, and B/A for the very neutron-rich 77,78,79Cu isotopes are determined from the proposed correlations. It is also proposed that the correlations between S n, S 2n and isotopic cross sections can be used to find the location of neutron drip line isotopes. Supported by Program for Science and Technology Innovation Talents at Universities of Henan Province (13HASTIT046), Natural and Science Foundation in Henan Province (162300410179), Program for the Excellent Youth at Henan Normal University (154100510007) and Y-D Song thanks the support from the Creative Experimental Project of National Undergraduate Students (CEPNU 201510476017)

  19. Energy spectra of neutrons accompanying the emission fission of 238U

    International Nuclear Information System (INIS)

    Smirenkin, G.N.; Lovchikova, G.N.; Trufanov, A.M.; Svirin, M.I.; Polyakov, A.V.; Vinogradov, V.A.; Dmitriev, V.D.; Boykov, G.S.

    1996-01-01

    The spectra of fission neutrons emitted from 238U are measured for the first time by the time-of-flight method at incident-neutron energies of 16.0 and 17.7 MeV. Analysis of the neutron spectra shows that experimental results at incident-neutron energies of 14.7, 16.0, and 17.7 MeV (above the threshold of chance fission) differ significantly from those obtained at a neutron energy of 2.9 MeV (below the threshold of chance fission). Owing to the prefission emission of neutrons, the observed spectra of neutrons from emission fission exhibit a characteristic growth of the neutron yield in both hard and soft sections of the spectrum of secondary neutrons. This growth manifests itself as a step in the first case and as a rise in the second case, where it results in a noticeable excess of neutrons over the statistical-model predictions for E<2 MeV. The first feature in the spectra of neutrons from emission fission can be associated with the nonequilibrium decay of an excited fissile nucleus. On the contrary, the origin of the second feature has yet to be clarified. Additional measurements of angular distributions of secondary neutrons may prove helpful in this respect

  20. Unfolding of neutron spectra from Godiva type critical assemblies

    International Nuclear Information System (INIS)

    Harvey, J.T.; Meason, J.L.; Wright, H.L.

    1976-01-01

    The results from three experiments conducted at the White Sands Missile Range Fast Burst Reactor Facility are discussed. The experiments were designed to measure the ''free-field'' neutron leakage spectrum and the neutron spectra from mildly perturbed environments. SAND-II was used to calculate the neutron spectrum utilizing several different trial input spectra for each experiment. Comparisons are made between the unfolded neutron spectrum for each trial input on the basis of the following parameters: average neutron energy (above 10 KeV), integral fluence (above 10 KeV), spectral index and the hardness parameter, phi/sub eq//phi

  1. Jet target intense neutron source

    International Nuclear Information System (INIS)

    Meier, K.L.

    1977-01-01

    A jet target Intense Neutron Source (INS) is being built by the Los Alamos Scientific Laboratory with DOE/MFE funding in order to perform radiation damage experiments on materials to be used in fusion power reactors. The jet target can be either a supersonic or a subsonic jet. Each type has its particular advantages and disadvantages, and either of the jets can be placed inside the spherical blanket converter which will be used to simulate a fusion reactor neutron environment. Preliminary mock-up experiments with a 16-mA, 115 keV, H + ion beam on a nitrogen gas supersonic jet show no serious problems in the beam formation, transport, or jet interaction

  2. Multi-group neutron transport theory

    International Nuclear Information System (INIS)

    Zelazny, R.; Kuszell, A.

    1962-01-01

    Multi-group neutron transport theory. In the paper the general theory of the application of the K. M. Case method to N-group neutron transport theory in plane geometry is given. The eigenfunctions (distributions) for the system of Boltzmann equations have been derived and the completeness theorem has been proved. By means of general solution two examples important for reactor and shielding calculations are given: the solution of a critical and albedo problem for a slab. In both cases the system of singular integral equations for expansion coefficients into a full set of eigenfunction distributions has been reduced to the system of Fredholm-type integral equations. Some results can be applied also to some spherical problems. (author) [fr

  3. NEMUS--the PTB Neutron Multisphere Spectrometer Bonner spheres and more

    CERN Document Server

    Wiegel, B

    2002-01-01

    The original Bonner sphere spectrometer as it is used and characterized by PTB consists of 12 polyethylene spheres with diameters from 7.62 cm (3'') to 45.72 cm (18'') and a sup 3 He-filled spherical proportional counter used as a central thermal-neutron-sensitive detector and as a bare or cadmium-shielded bare detector. In this paper, a set of four new spheres made of polyethylene with copper or lead inlets is introduced. All spheres are less than 18 kg in mass and their responses to high energy neutrons increase with energy as a result of the increasing (n,xn) cross-sections of copper and lead. The fluence response matrix was calculated up to 10 GeV using an extended neutron cross-section library (LA150) and the MCNP(X) Monte Carlo code. Calibration measurements with neutron energies up to 60 MeV were used to compare the calculated response functions to measured values. For measurements outside the laboratory, a miniaturized, battery-powered electronic set-up was developed. This system with the additional, ...

  4. Transport calculation of medium-energy protons and neutrons by Monte Carlo method

    International Nuclear Information System (INIS)

    Ban, Syuuichi; Hirayama, Hideo; Katoh, Kazuaki.

    1978-09-01

    A Monte Carlo transport code, ARIES, has been developed for protons and neutrons at medium energy (25 -- 500 MeV). Nuclear data provided by R.G. Alsmiller, Jr. were used for the calculation. To simulate the cascade development in the medium, each generation was represented by a single weighted particle and an average number of emitted particles was used as the weight. Neutron fluxes were stored by the collisions density method. The cutoff energy was set to 25 MeV. Neutrons below the cutoff were stored to be used as the source for the low energy neutron transport calculation upon the discrete ordinates method. Then transport calculations were performed for both low energy neutrons (thermal -- 25 MeV) and secondary gamma-rays. Energy spectra of emitted neutrons were calculated and compared with those of published experimental and calculated results. The agreement was good for the incident particles of energy between 100 and 500 MeV. (author)

  5. Imprints of the nuclear symmetry energy on gravitational waves from the axial w-modes of neutron stars

    International Nuclear Information System (INIS)

    Wen Dehua; Li Baoan; Krastev, Plamen G.

    2009-01-01

    The eigenfrequencies of the axial w-modes of oscillating neutron stars are studied using the continued fraction method with an equation of state (EOS) partially constrained by the recent terrestrial nuclear laboratory data. It is shown that the density dependence of the nuclear symmetry energy E sym (ρ) affects significantly both the frequencies and the damping times of these modes. Besides confirming the previously found universal behavior of the mass-scaled eigenfrequencies as functions of the compactness of neutron stars, we explored several alternative universal scaling functions. Moreover, the w II -mode is found to exist only for neutron stars having a compactness of M/R≥0.1078 independent of the EOS used.

  6. A {mu}TPC detector for the characterization of low energy neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Golabek, C., E-mail: cedric.golabek@irsn.fr [Laboratoire de Metrologie et de Dosimetrie des Neutrons, IRSN Cadarache, 13115 Saint-Paul-Lez-Durance (France); Billard, J. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut Polytechnique de Grenoble, 53 rue des Martyrs, 38026 Grenoble (France); Allaoua, A. [Laboratoire de Metrologie et de Dosimetrie des Neutrons, IRSN Cadarache, 13115 Saint-Paul-Lez-Durance (France); Bosson, G.; Bourrion, O.; Grignon, C.; Guillaudin, O. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut Polytechnique de Grenoble, 53 rue des Martyrs, 38026 Grenoble (France); Lebreton, L., E-mail: lena.lebreton@irsn.fr [Laboratoire de Metrologie et de Dosimetrie des Neutrons, IRSN Cadarache, 13115 Saint-Paul-Lez-Durance (France); Mayet, F. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut Polytechnique de Grenoble, 53 rue des Martyrs, 38026 Grenoble (France); Petit, M. [Laboratoire de Metrologie et de Dosimetrie des Neutrons, IRSN Cadarache, 13115 Saint-Paul-Lez-Durance (France); Richer, J.-P.; Santos, D. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut Polytechnique de Grenoble, 53 rue des Martyrs, 38026 Grenoble (France)

    2012-06-21

    The AMANDE facility produces monoenergetic neutron fields from 2 keV to 20 MeV for metrological purposes. To be considered as a reference facility, fluence and energy distributions of neutron fields have to be determined by primary measurement standards. For this purpose, a micro Time Projection Chamber is being developed to be dedicated to measure neutron fields with energy ranging from 8 keV up to 1 MeV. In this work we present simulations showing that such a detector, which allows the measurement of the ionization energy and the 3D reconstruction of the recoil nucleus, provides the determination of neutron energy and fluence of these neutron fields.

  7. Transmutation of minor actinides in a spherical torus tokamak fusion reactor, FDTR

    International Nuclear Information System (INIS)

    Feng, K.M.; Zhang, G.S.; Deng, M.G.

    2003-01-01

    In this paper, a concept for the transmutation of minor actinide (MA) nuclear wastes based on a spherical torus (ST) tokamak reactor, FDTR, is put forward. A set of plasma parameters suitable for the transmutation blanket was chosen. The 2-D neutron transport code TWODANT, the 3-D Monte Carlo code MCNP/4B, the 1-D neutron transport and burn-up calculation code BISON3.0 and their associated data libraries were used to calculate the transmutation rate, the energy multiplication factor and the tritium breeding ratio of the transmutation blanket. The calculation results for the system parameters and the actinide series isotopes for different operation times are presented. The engineering feasibility of the center-post (CP) of FDTR has been investigated and the results are also given. A preliminary neutronics calculation based on an ST transmutation blanket shows that the proposed system has a high transmutation capability for MA wastes. (author)

  8. Nuclear symmetry energy and the neutron skin in neutron-rich nuclei

    NARCIS (Netherlands)

    Dieperink, AEL; Dewulf, Y; Van Neck, D; Waroquier, M; Rodin, [No Value

    2003-01-01

    The symmetry energy for nuclear matter and its relation to the neutron. skin in finite nuclei is discussed. The symmetry energy as a function of density obtained in a self-consistent Green function approach is presented and compared to the results of other recent theoretical approaches. A partial

  9. Experimental research of plastic scintillation detector loaded 6Li neutron energy response

    International Nuclear Information System (INIS)

    Wang Lizong; Zhang Chuanfei; Peng Taiping; Guo Cun; Yang Hongqiong; Zhang Jianhua

    2005-01-01

    A new plastic scintillator, plastic scintillator loaded 6 Li, is brought forward and developed in this paper in order to increase low energy neutron sensitivity. Neutron sensitivity of several plastic scintillation detectors loaded 6 Li new developed in neutron energy range 0.2 MeV-5.0 MeV are calibrated by direct current at serial accelerator. Energy response curves of the detectors are obtained in this experiment. It is shown that this new plastic scintillation detector can increase low energy neutron sensitivity in experimental results. (authors)

  10. Next-Step Spherical Torus Experiment and Spherical Torus Strategy in the Fusion Energy Development Path

    International Nuclear Information System (INIS)

    Ono, M.; Peng, M.; Kessel, C.; Neumeyer, C.; Schmidt, J.; Chrzanowski, J.; Darrow, D.; Grisham, L.; Heitzenroeder, P.; Jarboe, T.; Jun, C.; Kaye, S.; Menard, J.; Raman, R.; Stevenson, T.; Viola, M.; Wilson, J.; Woolley, R.; Zatz, I.

    2003-01-01

    A spherical torus (ST) fusion energy development path which is complementary to proposed tokamak burning plasma experiments such as ITER is described. The ST strategy focuses on a compact Component Test Facility (CTF) and higher performance advanced regimes leading to more attractive DEMO and Power Plant scale reactors. To provide the physics basis for the CTF an intermediate step needs to be taken which we refer to as the ''Next Step Spherical Torus'' (NSST) device and examine in some detail herein. NSST is a ''performance extension'' (PE) stage ST with the plasma current of 5-10 MA, R = 1.5 m, and Beta(sub)T less than or equal to 2.7 T with flexible physics capability. The mission of NSST is to: (1) provide a sufficient physics basis for the design of CTF, (2) explore advanced operating scenarios with high bootstrap current fraction/high performance regimes, which can then be utilized by CTF, DEMO, and Power Plants, and (3) contribute to the general plasma/fusion science of high beta toroidal plasmas. The NSST facility is designed to utilize the Tokamak Fusion Test Reactor (or similar) site to minimize the cost and time required for the design and construction

  11. Mirror displacement energies and neutron skins

    International Nuclear Information System (INIS)

    Duflo, J.; Zuker, A.P.

    2002-01-01

    A gross estimate of the neutron skin [0.80(5)(N-Z)/A fm] is extracted from experimental proton radii, represented by a four parameter fit, and observed mirror displacement energies (CDE). The calculation of the latter relies on an accurately derived Coulomb energy and smooth averages of the charge symmetry breaking potentials constrained to state of the art values. The only free parameter is the neutron skin itself. The Nolen Schiffer anomaly is reduced to small deviations (rms=127 keV) that exhibit a secular trend. It is argued that with state of the art shell model calculations the anomaly should disappear. Highly accurate fits to proton radii emerge as a fringe benefit

  12. Calculation of neutron cross sections on iron up to 40 MeV

    International Nuclear Information System (INIS)

    Arthur, E.D.; Young, P.G.

    1980-01-01

    The development of high energy d + Li neutron sources for fusion materials radiation damage studies will require neutron cross sections up to 40 MeV. Experimental data above 15 MeV are generally sparse or nonexistent, and reliance must be placed upon nuclear-model calculations to produce the needed cross sections. To satisfy such requirements for the Fusion Materials Irradiation Test Facility (FMIT), neutron cross sections have been calculated for 54 56 Fe between 3 and 40 MeV. These results were joined to the existing ENDF/B-V evaluation below 3 MeV. In this energy range, most neutron reactions can be described using the Hauser-Feshbach statistical model with corrections for preequilibrium and direct-reaction effects. To properly use these models to obtain realistic cross sections, emphasis must be placed upon the determination of suitable input parameters (optical model sets, gamma-ray strength functions, level densities) valid over the energy range of the calculation. To do this, several types of independent data were used to arrive at consistent parameter sets as described

  13. Fast neutrons-induced apoptosis is Fas-independent in lymphoblastoid cells

    International Nuclear Information System (INIS)

    Fischer, Barbara; Benzina, Sami; Jeannequin, Pierre; Dufour, Patrick; Bergerat, Jean-Pierre; Denis, Jean-Marc; Gueulette, John; Bischoff, Pierre L.

    2005-01-01

    We have previously shown that ionizing radiation-induced apoptosis in human lymphoblastoid cells differs according to their p53 status, and that caspase 8-mediated cleavage of BID is involved in the p53-dependent pathway. In the present study, we investigated the role of Fas signaling in caspase 8 activation induced by fast neutrons irradiation in these cells. Fas and FasL expression was assessed by flow cytometry and by immunoblot. We also measured Fas aggregation after irradiation by fluorescence microscopy. We found a decrease of Fas expression after irradiation, but no change in Fas ligand expression. We also showed that, in contrast to the stimulation of Fas by an agonistic antibody, Fas aggregation did not occur after irradiation. Altogether, our data strongly suggest that fast neutrons induced-apoptosis is Fas-independent, even in p53-dependent apoptosis

  14. Transport of accelerator produced high energy neutrons though concrete

    International Nuclear Information System (INIS)

    Prabhakar Rao, G.; Sarkar, P.K.

    1996-01-01

    Development of a computational system for estimating the production and transport of high energy neutrons in particle accelerators is reported. The energy-angle distribution of neutrons from accelerated ions bombarding thick targets is calculated by a hybrid nuclear reaction model code, ALICE-91, modified to suit the purpose. Subsequent transmission of these neutrons through concrete slabs is treated using the anisotropic source-flux iteration technique (ASFIT) in the framework of a coupled neutron-gamma transport. Several parameters of both the codes have been optimized to obtain the transmitted dose through concrete. The calculations are found to be accurate and at the same time faster compared to the detailed Monte Carlo calculations. (author). 8 refs., 2 figs

  15. Preliminary investigations of Monte Carlo Simulations of neutron energy and LET spectra for fast neutron therapy facilities

    International Nuclear Information System (INIS)

    Kroc, T.K.

    2009-01-01

    No fast neutron therapy facility has been built with optimized beam quality based on a thorough understanding of the neutron spectrum and its resulting biological effectiveness. A study has been initiated to provide the information necessary for such an optimization. Monte Carlo studies will be used to simulate neutron energy spectra and LET spectra. These studies will be bench-marked with data taken at existing fast neutron therapy facilities. Results will also be compared with radiobiological studies to further support beam quality ptimization. These simulations, anchored by this data, will then be used to determine what parameters might be optimized to take full advantage of the unique LET properties of fast neutron beams. This paper will present preliminary work in generating energy and LET spectra for the Fermilab fast neutron therapy facility.

  16. Gamma-ray emission spectra from spheres with 14 MeV neutron source

    International Nuclear Information System (INIS)

    Yamamoto, Junji; Kanaoka, Takeshi; Murata, Isao; Takahashi, Akito; Sumita, Kenji

    1989-01-01

    Energy spectra of neutron-induced gamma-rays emitted from spherical samples were measured using a 14 MeV neutron source. The samples in use were LiF, Teflon:(CF 2 ) n , Si, Cr, Mn, Co, Cu, Nb, Mo, W and Pb. A diameter of the sphere was either 40 or 60 cm. The gamma-ray energy in the emission spectra covered the range from 500 keV to 10 MeV. Measured spectra were compared with transport calculations using the nuclear data files of JENDL-3T and ENDF/B-IV. The agreements between the measurements and the JENDL-3T calculations were good in the emission spectra for the low energy gamma-rays from inelastic scattering. (author)

  17. Correlation of the neutron yield from the plasma focus upon variations in the magnetic field energy of the discharge circuit

    Science.gov (United States)

    Ablesimov, V. E.; Dolin, Yu. N.; Kalinychev, A. E.; Tsibikov, Z. S.

    2017-10-01

    The relation between neutron yield Y and magnetic field energy variations Δ W in the discharge circuit has been studied for a Mather-type plasma-focus camera. The activation technique (activation of silver isotopes) has been used to measure the integral yield of DD neutrons from the source. The time dependence of the neutron yield has been recorded by scintillation detectors. For the device used in the investigations, the neutron yield exhibits a linear dependence on variations in the magnetic field energy Δ W in the discharge circuit at the instant of neutron generation. It is also found that this dependence is related to the initial deuteron pressure in the discharge chamber.

  18. Some neutronic studies on flux-trap type moderator

    International Nuclear Information System (INIS)

    Kiyanagi, Y.; Watanabe, N.

    1991-01-01

    The neutronic performance of a flux-trap type moderator was studied by computer simulation in connection with the KENS-II target-moderator system. It was confirmed that this system can provide 1.3-1.4 times higher neutron intensity than a traditional wing-geometry moderator system. (author)

  19. Calculational analysis of errors for various models of an experiment on measuring leakage neutron spectra

    International Nuclear Information System (INIS)

    Androsenko, A.A.; Androsenko, P.A.; Deeva, V.V.; Prokof'eva, Z.A.

    1990-01-01

    Analysis is made for the effect of mathematical model accuracy of the system concerned on the calculation results using the BRAND program system. Consideration is given to the impact of the following factors: accuracy of neutron source energy-angular characteristics description, various degrees of system geometry approximation, adequacy of Monte-Carlo method estimation to a real physical neutron detector. The calculation results analysis is made on the basis of the experiments on leakage neutron spectra measurement in spherical lead assemblies with the 14 MeV-neutron source in the centre. 4 refs.; 2 figs.; 10 tabs

  20. Neutron scattering and models: molybdenum

    International Nuclear Information System (INIS)

    Smith, A.B.

    1999-01-01

    A comprehensive interpretation of the fast-neutron interaction with elemental and isotopic molybdenum at energies of le 30 MeV is given. New experimental elemental-scattering information over the incident energy range 4.5 r a rrow 10 MeV is presented. Spherical, vibrational and dispersive models are deduced and discussed, including isospin, energy-dependent and mass effects. The vibrational models are consistent with the ''Lane potential''. The importance of dispersion effects is noted. Dichotomies that exist in the literature are removed. The models are vehicles for fundamental physical investigations and for the provision of data for applied purposes. A ''regional'' molybdenum model is proposed. Finally, recommendations for future work are made

  1. Wavelength-independent fringe spacing in rainbows from falling neutrons

    International Nuclear Information System (INIS)

    Berry, M.V.

    1982-01-01

    For particles with speed upsilon and mass m emitted isotropically from a point source and falling under gravity g, the quantal probability density is dominated by a paraboloidal caustic decorated with paraboloidal interference fringes. Near the caustic, the fringes have a spacing independent of upsilon and hence of wavelength, given by ΔR=3.53897x(h 2 /m 2 g)sup(1/3) for the first two (brightest) fringes at the level of the source. For neutrons in the Earth's field, ΔR=0.02617mm. The effect might be difficult to detect. (author)

  2. Estimation of uncertainties of displacement cross-sections for iron and tungsten at neutron irradiation energies above 0.1 MeV

    International Nuclear Information System (INIS)

    Konobeyev, A.Yu.; Fischer, U.; Simakov, S.P.

    2016-01-01

    The goal of this work is the evaluation of uncertainties of calculated atomic displacement cross sections for iron and tungsten irradiated with neutrons. Uncertainties were analysed for neutron incident energies above 0.1 MeV, which make the main contribution to the value of radiation damage rate for different types of nuclear or fusion reactors and neutron sources

  3. Fusion materials high energy-neutron studies. A status report

    International Nuclear Information System (INIS)

    Doran, D.G.; Guinan, M.W.

    1980-01-01

    The objectives of this paper are (1) to provide background information on the US Magnetic Fusion Reactor Materials Program, (2) to provide a framework for evaluating nuclear data needs associated with high energy neutron irradiations, and (3) to show the current status of relevant high energy neutron studies. Since the last symposium, the greatest strides in cross section development have been taken in those areas providing FMIT design data, e.g., source description, shielding, and activation. In addition, many dosimetry cross sections have been tentatively extrapolated to 40 MeV and integral testing begun. Extensive total helium measurements have been made in a variety of neutron spectra. Additional calculations are needed to assist in determining energy dependent cross sections

  4. F-type centers in neutron-irradiated AIN

    International Nuclear Information System (INIS)

    Atobe, Kozo; Honda, Makoto; Fukuoka, Noboru; Okada, Moritami; Nakagawa, Masuo.

    1990-01-01

    The production of point defects by neutron irradiation and thermal decay in sintered AIN polycrystal are investigated. The absorption band at 370 nm is observed after reactor neutron irradiation to a dose of 10 16 n/cm 2 (E > 0.1 MeV). The defect corresponding to the band is tentatively assigned as an F-type center from the optical absorption and electron spin resonance. (author)

  5. Energy dependence of the asymmetry-violated space parity of fragment emission from the 239PU fission by slow polarized neutrons

    International Nuclear Information System (INIS)

    Val'skij, G.V.; Zvezdkina, T.K.; Nikolaev, D.V.; Petrova, V.I.; Petrov, G.A.; Petukhov, A.K.; Pleva, Yu.S.; Tyukavin, V.A.

    1982-01-01

    Asymmetry violating parity in the fragment emission from fission of 239 Pu induced by polarized neutrons at six energy points in the interval 0.01 <= E <0.3 eV was measured. The results providing with an evidence in favour of the hypothesis that the asymmetry is independent on energy are discussed in view of the existing theoretical picture

  6. Energy response of neutron area monitor with silicon semiconductor detector

    International Nuclear Information System (INIS)

    Kitaguchi, Hiroshi; Izumi, Sigeru; Kobayashi, Kaoru; Kaihara, Akihisa; Nakamura, Takashi.

    1993-01-01

    A prototype neutron area monitor with a silicon semiconductor detector has been developed which has the energy response of 1 cm dose equivalent recommended by the ICRP-26. Boron and proton radiators are coated on the surface of the silicon semiconductor detector. The detector is set at the center of a cylindrical polyethylene moderator. This moderator is covered by a porous cadmium board which serves as the thermal neutron absorber. Neutrons are detected as α-particles generated by the nuclear reaction 10 B(n,α) 7 Li and as recoil protons generated by the interaction of fast neutrons with hydrogen. The neutron energy response of the monitor was measured using thermal neutrons and monoenergetic fast neutrons generated by an accelerator. The response was consistent with the 1 cm dose equivalent response required for the monitor within ±34% in the range of 0.025 - 15 Mev. (author)

  7. Precision cosmological measurements: Independent evidence for dark energy

    International Nuclear Information System (INIS)

    Bothun, Greg; Hsu, Stephen D.H.; Murray, Brian

    2008-01-01

    Using recent precision measurements of cosmological parameters, we re-examine whether these observations alone, independent of type Ia supernova surveys, are sufficient to imply the existence of dark energy. We find that best measurements of the age of the Universe t 0 , the Hubble parameter H 0 and the matter fraction Ω m strongly favor an equation of state defined by (w<-1/3). This result is consistent with the existence of a repulsive, acceleration-causing component of energy if the Universe is nearly flat

  8. Hot neutron stars at birth and energy release

    International Nuclear Information System (INIS)

    Takatsuka, Tatsuyuki

    1994-01-01

    For the discussion of hot neutron stars at birth, it is necessary to calculate the equation of state for a so-called 'supernova matter' consisting of a neutron-rich nuclear matter and degenerated leptons. One of the aims of this paper is to obtain the realistic results for the equation of state. In 10-20s after the birth, new born hot neutron stars are cooled down by neutrino diffusion process, and gradually contract to usual cold neutron starts. It is another aim of this paper to determine how much energy is released during this cooling stage. The points to which attention was paid are explained. A three-nucleon interaction was introduced phenomenologically, as a two-nucleon interaction is insufficient to satisfy the empirical saturation property of symmetric nuclear matters. The separation of uncertain part from well-known part has the merit to clarify the dependence of the results on the present theoretical uncertainties. The validity of the simplified calculation as an approximation for the exact calculation is discussed. The results by both calculations were compared for the case of hot symmetric nuclear matters. The comparison of the density profiles for a hot neutron star and a cold neutron star is shown. The binding energy for hot and cold neutron stars was plotted. These results are examined. (K.I.)

  9. High energy neutron source for materials research and development

    International Nuclear Information System (INIS)

    Odera, M.

    1989-01-01

    Requirements for neutron source for nuclear materials research are reviewed and ESNIT, Energy Selective Neutron Irradiation Test facility proposed by JAERI is discussed. Its principal aims of a wide neutron energy tunability and spectra peaking at each energy to enable characterization of material damage process are demanding but attractive goals which deserve detailed study. It is also to be noted that the requirements make a difference in facility design from those of FMIT, IFMIF and other high energy intense neutron sources built or planned to date. Areas of technologies to be addressed to realize the ESNIT facility are defined and discussed. In order to get neutron source having desired spectral characteristics keeping moderate intensity, projectile and target combinations must be examined including experimentation if necessary. It is also desired to minimize change of flux density and energy spectrum according to location inside irradiation chamber. Extended target or multiple targets configuration might be a solution as well as specimen rotation and choice of combination of projectile and target which has minimum velocity of the center of mass. Though relevant accelerator technology exists, it is to be stressed that considerable efforts must be paid, especially in the area of target and irradiation devices to get ESNIT goal. Design considerations to allow hands-on maintenance and future upgrading possibility are important either, in order to exploit the facility fully for nuclear materials research and development. (author)

  10. Progress on a spherical TPC for low energy neutrino detection

    International Nuclear Information System (INIS)

    Aune, S; Colas, P; Deschamps, H; Dolbeau, J; Fanourakis, G; Ribas, E Ferrer; Enqvist, T; Geralis, T; Giomataris, Y; Gorodetzky, P; Gounaris, G J; Gros, M; Irastorza, I G; Kousouris, K; Lepeltier, V; Morales, J; Patzak, T; Paschos, E A; Salin, P; Savvidis, I; Vergados, J D

    2006-01-01

    The new concept of the spherical TPC aims at relatively large target masses with low threshold and background, keeping an extremely simple and robust operation. Such a device would open the way to detect the neutrino-nucleus interaction, which, although a standard process, remains undetected due to the low energy of the neutrino-induced nuclear recoils. The progress in the development of the first 1 m 3 prototype at Saclay is presented. Other physics goals of such a device could include supernova detection, low energy neutrino oscillations and study of non-standard properties of the neutrino, among others

  11. The intense neutron generator and future factory type ion accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, W B

    1968-07-01

    A neutron factory is likely to sell its product in the form of isotopes. To ay neutron factories are nuclear reactors. Ion accelerators may also produce isotopes by direct interaction and, at high enough energies, mesons and hyperons. The challenge of the electrical production of neutrons goes far beyond the isotope market. It challenges the two popular concepts for long term large scale energy, the fast breeder reactor and controlled thermonuclear fusion. For this use about 4% of nuclear generated power would be applied in a feedback loop generating extra neutrons. Competition rests on operating and processing costs. The Intense Neutron Generator proposal now cancelled would have been full scale for such a use, but much further advance in accelerator engineering is required and anticipated. Perhaps most promising is the application of the ion drag principle in which rings of fast electrons are accelerated along their axis dragging ions with them by electrostatic attraction. Due to the much larger mass of the ions they can acquire much higher energy than the electrons and the process could be efficient. Such accelerators have not yet been made but experimental and theoretical studies are promising. (author)

  12. The intense neutron generator and future factory type ion accelerators

    International Nuclear Information System (INIS)

    Lewis, W.B.

    1968-01-01

    A neutron factory is likely to sell its product in the form of isotopes. To ay neutron factories are nuclear reactors. Ion accelerators may also produce isotopes by direct interaction and, at high enough energies, mesons and hyperons. The challenge of the electrical production of neutrons goes far beyond the isotope market. It challenges the two popular concepts for long term large scale energy, the fast breeder reactor and controlled thermonuclear fusion. For this use about 4% of nuclear generated power would be applied in a feedback loop generating extra neutrons. Competition rests on operating and processing costs. The Intense Neutron Generator proposal now cancelled would have been full scale for such a use, but much further advance in accelerator engineering is required and anticipated. Perhaps most promising is the application of the ion drag principle in which rings of fast electrons are accelerated along their axis dragging ions with them by electrostatic attraction. Due to the much larger mass of the ions they can acquire much higher energy than the electrons and the process could be efficient. Such accelerators have not yet been made but experimental and theoretical studies are promising. (author)

  13. Nuclear symmetry energy and stability of matter in neutron stars

    International Nuclear Information System (INIS)

    Kubis, Sebastian

    2007-01-01

    It is shown that the nuclear symmetry energy is the key quantity in the stability consideration in neutron star matter. The symmetry energy controls the position of crust-core transition and also may lead to new effects in the inner core of neutron star

  14. Fast-neutron elastic-scattering cross sections of elemental tin

    International Nuclear Information System (INIS)

    Budtz-Jorgensen, C.; Guenther, P.T.; Smith, A.

    1982-07-01

    Broad-resolution neutron-elastic-scattering cross sections of elemental tin are measured from 1.5 to 4.0 MeV. Incident-energy intervals are approx. 50 keV below 3.0 MeV and approx. 200 keV at higher energies. Ten to twenty scattering angles are used, distributed between approx. 20 and 160 0 . The experimental results are used to deduce the parameters of a spherical optical-statistical model and they are also compared with corresponding values given in ENDF/B-V

  15. Neutron dose rate analysis on HTGR-10 reactor using Monte Carlo code

    Science.gov (United States)

    Suwoto; Adrial, H.; Hamzah, A.; Zuhair; Bakhri, S.; Sunaryo, G. R.

    2018-02-01

    The HTGR-10 reactor is cylinder-shaped core fuelled with kernel TRISO coated fuel particles in the spherical pebble with helium cooling system. The outlet helium gas coolant temperature outputted from the reactor core is designed to 700 °C. One advantage HTGR type reactor is capable of co-generation, as an addition to generating electricity, the reactor was designed to produce heat at high temperature can be used for other processes. The spherical fuel pebble contains 8335 TRISO UO2 kernel coated particles with enrichment of 10% and 17% are dispersed in a graphite matrix. The main purpose of this study was to analysis the distribution of neutron dose rates generated from HTGR-10 reactors. The calculation and analysis result of neutron dose rate in the HTGR-10 reactor core was performed using Monte Carlo MCNP5v1.6 code. The problems of double heterogeneity in kernel fuel coated particles TRISO and spherical fuel pebble in the HTGR-10 core are modelled well with MCNP5v1.6 code. The neutron flux to dose conversion factors taken from the International Commission on Radiological Protection (ICRP-74) was used to determine the dose rate that passes through the active core, reflectors, core barrel, reactor pressure vessel (RPV) and a biological shield. The calculated results of neutron dose rate with MCNP5v1.6 code using a conversion factor of ICRP-74 (2009) for radiation workers in the radial direction on the outside of the RPV (radial position = 220 cm from the center of the patio HTGR-10) provides the respective value of 9.22E-4 μSv/h and 9.58E-4 μSv/h for enrichment 10% and 17%, respectively. The calculated values of neutron dose rates are compliant with BAPETEN Chairman’s Regulation Number 4 Year 2013 on Radiation Protection and Safety in Nuclear Energy Utilization which sets the limit value for the average effective dose for radiation workers 20 mSv/year or 10μSv/h. Thus the protection and safety for radiation workers to be safe from the radiation source has

  16. A sensitive search for dark energy through chameleon scalar fields using neutron interferometry

    International Nuclear Information System (INIS)

    Snow, W M; Li, K; Skavysh, V; Arif, M; Huber, M; Heacock, B; Young, A R; Pushin, D

    2015-01-01

    The physical origin of the dark energy, which is postulated to cause the accelerated expansion rate of the universe, is one of the major open questions of cosmology. A large subset of theories postulate the existence of a scalar field with a nonlinear coupling to matter chosen so that the effective range and/or strength of the field is greatly suppressed unless the source is placed in vacuum. We describe a measurement using neutron interferometry which can place a stringent upper bound on chameleon fields proposed as a solution to the problem of the origin of dark energy of the universe in the regime with a strongly-nolinear coupling term. In combination with other experiments searching for exotic short-range forces and laser-based measurements, slow neutron experiments are capable of eliminating this and many similar types of scalar-field-based dark energy models by laboratory experiments

  17. Neutron beam experiments using nuclear research reactors: honoring the retirement of professor Bernard W. Wehring -II. 5. Testing Moderating Detection Systems with 252Cf-Based Reference Neutron Fields

    International Nuclear Information System (INIS)

    Hertel, Nolan E.; Sweezy, Jeremy; Sauber, Jeremiah S.; Vaughn, David; Cook, Andrew; Tays, Jeff; Ro, Tae-Ik

    2001-01-01

    In recent years, Georgia Institute of Technology (Georgia Tech) has been involved in a number of neutron dosimetry research projects. Several reference neutron fields are now available for such projects. They are all based on the use of a 252 Cf source. The source can be used by itself to create a reference un-moderated 252 Cf neutron field, or it can be placed inside several different moderating assemblies. The spectra created by placing the source inside these assemblies and the un-moderated source are employed to investigate detector and dosimeter responses. Currently, the set of moderators available includes a 30-cm diam cadmium-covered D 2 O spherical shell, a 30-cm-thick iron spherical shell, a 30-cm-diam polyethylene spherical shell, an 18.3-cm-thick tungsten spherical shell, a 16-cm-thick lead spherical shell, and a 9-cm-thick tantalum spherical shell. In addition, the 252 Cf source can be placed inside a neutron howitzer recently constructed at Georgia Tech. The howitzer is a WEP cylinder loaded with boron that has a 10.16-cm-diam cylindrical opening. When the source is placed in the cylindrical penetration of the howitzer, a neutron field ∼30 cm in diameter is created at a distance of 50 cm from the californium source. Over the last few years, Bonner sphere spectrometers using LiI(Eu) scintillators and LiF thermoluminescence dosimeters have been calibrated using this facility at Georgia Tech. Recently, the Neely Nuclear Research Center (NNRC) acquired an LB 6411 neutron probe (product of EG and G Berthold). This probe is designed to measure ambient dose equivalent in accordance with International Commission on Radiological Protection Publication 60 recommendations. It consists of a cylindrical 3 He proportional counter surrounded by a 25-cm-diam spherical polyethylene moderator. Its neutron response is optimized for dose rate measurements of neutrons between thermal energies and 20 MeV (Ref. 5). As a test of the instrument's ability to measure ambient

  18. Violation of Bell-type inequality in single-neutron interferometry

    International Nuclear Information System (INIS)

    Hasegawa, Y.; Badurek, G.; Baron, M.; Rauch, H.; Loidl, R.

    2003-01-01

    Full text: We present an interferometric experiment with single spin-1/2 neutrons to demonstrate the violation of Bell-type inequality. The total wave function of neutrons is described by a two-dimensional Hilbert space. Appropriate combinations of the direction of the spin analysis and the position of the phase shifter allow to demonstrate the violation of the Bell-type inequality. The discussions are given on the violation of the Bell-type inequality in terms of beam polarizations and an entanglement-induced correlation in our experiment. (author)

  19. Determining space-energy distribution of thermal neutrons in heterogeneous cylindrically symmetric reactor cell, Master Thesis; Odredjivanje prostorno energetske raspodele fluksa termalnih neutrona u heterogenoj cilindricno simetricnoj reaktorskoj celiji, Magistarski rad

    Energy Technology Data Exchange (ETDEWEB)

    Matausek, M V [Boris Kidric Institute of Nuclear Sciences Vinca, Belgrade (Yugoslavia)

    1966-06-15

    A combination of multigroup method and P{sub 3} approximation of spherical harmonics method was chosen for calculating space-energy distribution of thermal neutron flux in elementary reactor cell. Application of these methods reduced solution of complicated transport equation to the problem of solving an inhomogeneous system of six ordinary firs-order differential equations. A procedure is proposed which avoids numerical solution and enables analytical solution when applying certain approximations. Based on this approach, computer codes were written for ZUSE-Z-23 computer: SIGMA code for calculating group constants for a given material; MULTI code which uses results of SIGMA code as input and calculates spatial ana energy distribution of thermal neutron flux in a reactor cell. Calculations of thermal neutron spectra for a number of reactor cells were compared to results available from literature. Agreement was satisfactory in all the cases, which proved the correctness of the applied method. Some possibilities for improving the precision and acceleration of the calculation process were found during calculation. (author)

  20. Spherical collapse model in time varying vacuum cosmologies

    International Nuclear Information System (INIS)

    Basilakos, Spyros; Plionis, Manolis; Sola, Joan

    2010-01-01

    We investigate the virialization of cosmic structures in the framework of flat Friedmann-Lemaitre-Robertson-Walker cosmological models, in which the vacuum energy density evolves with time. In particular, our analysis focuses on the study of spherical matter perturbations, as they decouple from the background expansion, 'turn around', and finally collapse. We generalize the spherical collapse model in the case when the vacuum energy is a running function of the Hubble rate, Λ=Λ(H). A particularly well-motivated model of this type is the so-called quantum field vacuum, in which Λ(H) is a quadratic function, Λ(H)=n 0 +n 2 H 2 , with n 0 ≠0. This model was previously studied by our team using the latest high quality cosmological data to constrain its free parameters, as well as the predicted cluster formation rate. It turns out that the corresponding Hubble expansion history resembles that of the traditional ΛCDM cosmology. We use this Λ(t)CDM framework to illustrate the fact that the properties of the spherical collapse model (virial density, collapse factor, etc.) depend on the choice of the considered vacuum energy (homogeneous or clustered). In particular, if the distribution of the vacuum energy is clustered, then, under specific conditions, we can produce more concentrated structures with respect to the homogeneous vacuum energy case.

  1. Few-MeV neutrons incident on yttrium

    International Nuclear Information System (INIS)

    Budtz-Jorgensen, C.; Guenther, P.; Smith, A.; Whalen, J.

    1982-09-01

    Neutron total and scattering cross sections of elemental yttrium are measured in the few-MeV region with broad resolutions. The total-cross section measurements extend from approx. = 0.5 to 4.2 MeV in steps of less than or equal to 0.1 MeV. Neutron elastic- and inelastic-scattering cross sections are measured from approx. = 1.5 to 4.0 MeV, at incident-neutron energy intervals of less than or equal to 50 keV and at ten or more scattering angles distributed between 20 and 160 deg. Inelastically-scattered neutron groups are observed corresponding to the excitation of levels at 909 +- 23, 1504 +- 20, 1747 +- 16, 2224 +- 16, 2567 +- 26, 2889 +- 12 and 3104 +- 10 keV. The experimental results are discussed in terms of the spherical optical-statistical, coupled-channels and core-coupling models and compared with corresponding quantities given in the evaluated nuclear data file ENDF/B-V

  2. Generating energy dependent neutron flux maps for effective ...

    African Journals Online (AJOL)

    For activation analysis and irradiation scheme of miniature neutron source reactor, designers or engineers usually require information on thermal neutron flux levels and other energy group flux levels (such as fast, resonance and epithermal). A methodology for readily generating such flux maps and flux profiles for any ...

  3. The isotope density inverse problem in multigroup neutron transport

    International Nuclear Information System (INIS)

    Zazula, J.M.

    1981-01-01

    The inverse problem for stationary multigroup anisotropic neutron transport is discussed in order to search for isotope densities in multielement medium. The spatial- and angular-integrated form of neutron transport equation, in terms of the flux in a group - density of an element spatial correlation, leads to a set of integral functionals for the densities weighted by the group fluxes. Some methods of approximation to make the problem uniquently solvable are proposed. Particularly P 0 angular flux information and the spherically-symetrical geometry of an infinite medium are considered. The numerical calculation using this method related to sooner evaluated direct problem data gives promising agreement with primary densities. This approach would be the basis for further application in an elemental analysis of a medium, using an isotopic neutron source and a moving, energy-dependent neutron detector. (author)

  4. Neutron dosimetry at a high-energy electron-positron collider

    Science.gov (United States)

    Bedogni, Roberto

    Electron-positron colliders with energy of hundreds of MeV per beam have been employed for studies in the domain of nuclear and sub-nuclear physics. The typical structure of such a collider includes an LINAC, able to produce both types of particles, an accumulator ring and a main ring, whose diameter ranges from several tens to hundred meters and allows circulating particle currents of several amperes per beam. As a consequence of the interaction of the primary particles with targets, shutters, structures and barriers, a complex radiation environment is produced. This paper addresses the neutron dosimetry issues associated with the operation of such accelerators, referring in particular to the DAΦ NE complex, operative since 1997 at INFN-Frascati National Laboratory (Italy). Special attention is given to the active and passive techniques used for the spectrometric and dosimetric characterization of the workplace neutron fields, for radiation protection dosimetry purposes.

  5. High accuracy measurement of the $^{235}$U(n,f) reaction cross-section in the 10-30 keV neutron energy range

    CERN Multimedia

    The analysis of the neutron flux of n_TOF (in EAR1) revealed an anomaly in the 10-30 keV neutron energy range. While the flux extracted on the basis of the $^{6}$Li(n,t)$^{4}$He and $^{10}$B(n,$\\alpha$)$^{7}$Li reactions mostly agreed with each other and with the results of FLUKA simulations of the neutron beam, the one based on the $^{235}$U(n,f) reaction was found to be systematically lower, independently of the detection system used. A possible explanation is that the $^{235}$U(n,f) crosssection in that energy region, where in principle should be known with an uncertainty of 1%, may be systematically overestimated. Such a finding, which has a negligible influence on thermal reactors, would be important for future fast critical or subcritical reactors. Furthermore, its interest is more general, since the $^{235}$U(n,f) reaction is often used at that energy to determine the neutron flux, or as reference in measurements of fission cross section of other actinides. We propose to perform a high-accuracy, high-r...

  6. A coaxial double cylindrical TEPC for the microdosimetry of selected neutron energy bands in mixed fields of fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Saion, E.B.; Watt, D.E. (Saint Andrews Univ. (UK). Dept. of Physics); East, B.W. (Scottish Universities Research and Reactor Centre, Glasgow (UK)); Colautti, P. (Istituto Nazionale di Fisica Nucleare, Padua (Italy))

    1990-01-01

    A new low pressure tissue-equivalent proportional counter (TEPC) in a coaxial double cylindrical form has been developed to measure separately the microdose spectrum from any desired energy band of neutrons in the presence of mixed fields of faster neutrons, by selecting the thickness of the common TE dividing wall to be equivalent to the corresponding maximum proton ranges and by appropriate use of coincidence/anti-coincidence pulse arrangements. This thickness ensures charged particle equilibrium for the relevant neutron energy. Event spectra due to recoils generated by faster neutrons which interact with both the counters are removed completely by anti-coincidence techniques, thereby optimising the sensitivity of the inner microdosemeter to the event spectra of interest. The ability of this counter to discriminate in favour of events due to neutrons of energy <850 keV was achieved in microdosimetric measurements from mixed fields of a nuclear reactor. Mean values of lineal energy and quality factor for neutrons of energy <850 keV from a nuclear reactor were determined from the anti-coincidence spectrum. Good discrimination against {gamma} ray induced events is also achieved for the spectrum recorded in the anti-coincidence mode. This is an advantageous feature for other applications and requires further investigation. (author).

  7. A coaxial double cylindrical TEPC for the microdosimetry of selected neutron energy bands in mixed fields of fast neutrons

    International Nuclear Information System (INIS)

    Saion, E.B.; Watt, D.E.; Colautti, P.

    1990-01-01

    A new low pressure tissue-equivalent proportional counter (TEPC) in a coaxial double cylindrical form has been developed to measure separately the microdose spectrum from any desired energy band of neutrons in the presence of mixed fields of faster neutrons, by selecting the thickness of the common TE dividing wall to be equivalent to the corresponding maximum proton ranges and by appropriate use of coincidence/anti-coincidence pulse arrangements. This thickness ensures charged particle equilibrium for the relevant neutron energy. Event spectra due to recoils generated by faster neutrons which interact with both the counters are removed completely by anti-coincidence techniques, thereby optimising the sensitivity of the inner microdosemeter to the event spectra of interest. The ability of this counter to discriminate in favour of events due to neutrons of energy <850 keV was achieved in microdosimetric measurements from mixed fields of a nuclear reactor. Mean values of lineal energy and quality factor for neutrons of energy <850 keV from a nuclear reactor were determined from the anti-coincidence spectrum. Good discrimination against γ ray induced events is also achieved for the spectrum recorded in the anti-coincidence mode. This is an advantageous feature for other applications and requires further investigation. (author)

  8. Influence of {gamma} and neutron irradiation on the magnetic properties of Nd Fe B, Alnico, and Mn Al type permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Jipa, S; Setnescu, R; Kappel, W; Alexandru, St [Institute of Research and Design for Electrical Engineering, ICPE - Electrostatica, Splaiul Unirii 313, Sect. 3, R-74204 Bucharest (Romania)

    1996-12-31

    The influence of {gamma} and neutron irradiation on the magnetic properties of Nd Fe B, Alnico and Mn Al type permanent magnets was studied. With the used neutron energies and fluences, no changes in remanent induction values for Nd Fe B type permanent magnets are shown. For Alnico type permanent magnets the remanent induction changes are due to reversible variation of the magnetization directions. Only in case of Mn Al type permanent magnets irreversible structural changes take place, which lead to irreversible losses of induction. (author) 4 figs., 2 tabs., 12 refs. (author).

  9. Influence of γ and neutron irradiation on the magnetic properties of Nd Fe B, Alnico, and Mn Al type permanent magnets

    International Nuclear Information System (INIS)

    Jipa, S.; Setnescu, R.; Kappel, W.; Alexandru, St.

    1995-01-01

    The influence of γ and neutron irradiation on the magnetic properties of Nd Fe B, Alnico and Mn Al type permanent magnets was studied. With the used neutron energies and fluences, no changes in remanent induction values for Nd Fe B type permanent magnets are shown. For Alnico type permanent magnets the remanent induction changes are due to reversible variation of the magnetization directions. Only in case of Mn Al type permanent magnets irreversible structural changes take place, which lead to irreversible losses of induction. (author) 4 figs., 2 tabs., 12 refs. (author)

  10. Detecting neutrons by forward recoil protons at the Energy & Transmutation facility: Detector development and calibration with 14.1-MeV neutrons

    Science.gov (United States)

    Afanasev, S.; Vishnevskiy, A.; Vishnevskiy, D.; Rogachev, A.; Tyutyunnikov, S.

    2017-05-01

    As part of the Energy & Transmutation project, we are developing a detector for neutrons with energies in the 10-100 MeV range emitted from the target irradiated by a charged-particle beam. The neutron is detected by measuring the time-of-flight and total kinetic energy of the forward-going recoil proton [1] knocked out at a small angle from a thin layer of plastic scintillator, which has to be selected against an intense background created by γ quanta, scattered neutrons, and charged particles. On the other hand, neutron energy has to be measured over the full range with no extra tuning of the detector operation regime. Initial measurements with a source of 14.1-MeV neutrons are reported.

  11. Simulation of a high energy neutron irradiation facility at beamline 11 of the China Spallation Neutron Source

    Energy Technology Data Exchange (ETDEWEB)

    Tairan, Liang [School of Physics and Electronic Information Inner Mongolia University for the Nationalities, Tongliao 028043 (China); Zhiduo, Li [Dongguan Branch, Institute of High Energy Physics, CAS, Beijing 100049 (China); Wen, Yin, E-mail: wenyin@aphy.iphy.ac.cn [Dongguan Branch, Institute of High Energy Physics, CAS, Beijing 100049 (China); Institute of Physics, CAS, P.O. Box 603, Beijing 100190 (China); Fei, Shen [Dongguan Branch, Institute of High Energy Physics, CAS, Beijing 100049 (China); Quanzhi, Yu [Dongguan Branch, Institute of High Energy Physics, CAS, Beijing 100049 (China); Institute of Physics, CAS, P.O. Box 603, Beijing 100190 (China); Tianjiao, Liang [Dongguan Branch, Institute of High Energy Physics, CAS, Beijing 100049 (China)

    2017-07-11

    The China Spallation Neutron Source (CSNS) will accommodate 20 neutron beamlines at its first target station. These beamlines serve different purposes, and beamline 11 is designed to analyze the degraded models and damage mechanisms, such as Single Event Effects in electronic components and devices for aerospace electronic systems. This paper gives a preliminary discussion on the scheme of a high energy neutron irradiation experiment at the beamline 11 shutter based on the Monte Carlo simulation method. The neutron source term is generated by calculating the neutrons scattering into beamline 11 with a model that includes the target-moderator-reflector area. Then, the neutron spectrum at the sample position is obtained. The intensity of neutrons with energy of hundreds of MeV is approximately 1E8 neutron/cm{sup 2}/s, which is useful for experiments. The displacement production rate and gas productions are calculated for common materials such as tungsten, tantalum and SS316. The results indicate that the experiment can provide irradiation dose rate ranges from 1E-5 to 1E-4 dpa per operating year. The residual radioactivity is also calculated for regular maintenance work. These results give the basic reference for the experimental design.

  12. Microdosimetry of monoenergetic neutrons

    International Nuclear Information System (INIS)

    Srdoc, D.; Marino, S.A.

    1993-01-01

    Tissue spheres 0.25, 0.5, 1.0, 2.0, 4.0, and 8.0 μm in diameter were simulated using a wall-less spherical counter filled with a propane-based tissue-equivalent gas. Microdosimetric spectra corresponding to these site sizes were measured for five neutron energies (0.22, 0.44, 1.5, 6, and 14 MeV) and the related mean values bar Y F and bar Y D were calculated for several site sizes and neutron energies. An elaborate calibration technique combining soft x-rays, a 55 Fe photon source, and a 244 Cm collimated source of alpha particles was used throughout the measurement. The spectra and their mean values are compared with theoretically calculated values for ICRU tissue. The agreement between the calculated and the measured data is good in spite of a systematic discrepancy, which could be attributed, in part, to the difference in elemental composition between the tissue-equivalent gas and plastic used in the counter, and the ICRU standard tissue used in the calculations

  13. Ionizing Energy Depositions After Fast Neutron Interactions in Silicon

    CERN Document Server

    Bergmann, Benedikt; Caicedo, Ivan; Kierstead, James; Takai, Helio; Frojdh, Erik

    2016-01-01

    In this study we present the ionizing energy depositions in a 300 μm thick silicon layer after fast neutron impact. With the Time-of-Flight (ToF) technique, the ionizing energy deposition spectra of recoil silicons and secondary charged particles were assigned to (quasi-)monoenergetic neutron energies in the range from 180 keV to hundreds of MeV. We show and interpret representative measured energy spectra. By separating the ionizing energy losses of the recoil silicon from energy depositions by products of nuclear reactions, the competition of ionizing (IEL) and non-ionizing energy losses (NIEL) of a recoil silicon within the silicon lattice was investigated. The data give supplementary information to the results of a previous measurement and are compared with different theoretical predictions.

  14. Flux distribution in phantom for biomedical use of beam-type thermal neutrons

    International Nuclear Information System (INIS)

    Aoki, Kazuhiko; Kobayashi, Tooru; Kanda, Keiji; Kimura, Itsuro

    1985-01-01

    For boron neutron capture therapy, the thermal neutron beam is worth using as therapeutic neutron irradiation without useless and unfavorable exposure of normal tissues around tumor and for microanalysis system to measure ppm-order 10 B concentrations in tissue and to search for the location of the metastasis of tumor. In the present study, the thermal neutron flux distribution in a phantom, when beam-type thermal neutrons were incident on it, was measured at the KUR Neutron Guide Tube. The measurements were carried out by two different methods using indium foil. The one is an ordinary foil activation technique by using the 115 In(n, γ) 116m 1 In reactions, while the other is to detect γ-rays from the 115 In(n, γ) 116m 2 In reactions during neutron irradiations with a handy-type Ge detector. The calculations with DOT 3.5 were performed to examine thermal neutron flux in the phantom for various beam size and phantom size. The experimental and calculated results are in good agreement and it is shown that the second type measurement has a potential for practical application as a new monitoring system of the thermal neutron flux in a living body for boron neutron capture therapy. (author)

  15. Two-dimensional time dependent Riemann solvers for neutron transport

    International Nuclear Information System (INIS)

    Brunner, Thomas A.; Holloway, James Paul

    2005-01-01

    A two-dimensional Riemann solver is developed for the spherical harmonics approximation to the time dependent neutron transport equation. The eigenstructure of the resulting equations is explored, giving insight into both the spherical harmonics approximation and the Riemann solver. The classic Roe-type Riemann solver used here was developed for one-dimensional problems, but can be used in multidimensional problems by treating each face of a two-dimensional computation cell in a locally one-dimensional way. Several test problems are used to explore the capabilities of both the Riemann solver and the spherical harmonics approximation. The numerical solution for a simple line source problem is compared to the analytic solution to both the P 1 equation and the full transport solution. A lattice problem is used to test the method on a more challenging problem

  16. Determination of neutron energy spectrum at a pneumatic rabbit station of a typical swimming pool type material test research reactor

    International Nuclear Information System (INIS)

    Malkawi, S.R.; Ahmad, N.

    2002-01-01

    The method of multiple foil activation was used to measure the neutron energy spectrum, experimentally, at a rabbit station of Pakistan Research Reactor-1 (PARR-1), which is a typical swimming pool type material test research reactor. The computer codes MSITER and SANDBP were used to adjust the spectrum. The pre-information required by the adjustment codes was obtained by modelling the core and its surroundings in three-dimensions by using the one dimensional transport theory code WIMS-D/4 and the multidimensional finite difference diffusion theory code CITATION. The input spectrum covariance information required by MSITER code was also calculated from the CITATION output. A comparison between calculated and adjusted spectra shows a good agreement

  17. Applicability of the two-angle differential method to response measurement of neutron-sensitive devices at the RCNP high-energy neutron facility

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Akihiko, E-mail: aki-masuda@aist.go.jp [National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Matsumoto, Tetsuro [National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Iwamoto, Yosuke [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai, Naka, Ibaraki 319-1195 (Japan); Hagiwara, Masayuki [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Satoh, Daiki; Sato, Tatsuhiko [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai, Naka, Ibaraki 319-1195 (Japan); Iwase, Hiroshi [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Yashima, Hiroshi [Research Reactor Institute, Kyoto University, 2-1010 Asashiro-nishi, Kumatori, Sennan, Osaka 590-0494 (Japan); Nakane, Yoshihiro [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai, Naka, Ibaraki 319-1195 (Japan); Nishiyama, Jun [Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8550 (Japan); Shima, Tatsushi; Tamii, Atsushi; Hatanaka, Kichiji [Research Center for Nuclear Physics (RCNP), Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Harano, Hideki [National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Nakamura, Takashi [Cyclotron and Radioisotope Center (CYRIC), Tohoku University, 6-3 Aramaki, Aoba, Sendai, Miyagi 980-8578 (Japan)

    2017-03-21

    Quasi-monoenergetic high-energy neutron fields induced by {sup 7}Li(p,n) reactions are used for the response evaluation of neutron-sensitive devices. The quasi-monoenergetic high-energy field consists of high-energy monoenergetic peak neutrons and unwanted continuum neutrons down to the low-energy region. A two-angle differential method has been developed to compensate for the effect of the continuum neutrons in the response measurements. In this study, the two-angle differential method was demonstrated for Bonner sphere detectors, which are typical examples of moderator-based neutron-sensitive detectors, to investigate the method's applicability and its dependence on detector characteristics. Experiments were performed under 96–387 MeV quasi-monoenergetic high-energy neutron fields at the Research Center for Nuclear Physics (RCNP), Osaka University. The measurement results for large high-density polyethylene (HDPE) sphere detectors agreed well with Monte Carlo calculations, which verified the adequacy of the two-angle differential method. By contrast, discrepancies were observed in the results for small HDPE sphere detectors and metal-induced sphere detectors. The former indicated that detectors that are particularly sensitive to low-energy neutrons may be affected by penetrating neutrons owing to the geometrical features of the RCNP facility. The latter discrepancy could be consistently explained by a problem in the evaluated cross-section data for the metals used in the calculation. Through those discussions, the adequacy of the two-angle differential method was experimentally verified, and practical suggestions were made pertaining to this method.

  18. Fundamental physics with low-energy neutrons

    International Nuclear Information System (INIS)

    Barrón-Palos, Libertad

    2016-01-01

    Low-energy neutrons are playing a prominent role in a growing number of fundamental physics studies. This paper provides a brief description of the physics that some of the experiments in the area are addressing. (paper)

  19. Evaluation of neutron nuclear data of 241pu for JENDL-2

    International Nuclear Information System (INIS)

    Kikuchi, Yasuyuki; Sekine, Nobuo

    1984-06-01

    Neutron nuclear data of 241 Pu were newly evaluated for JENDL-2. Evaluated quantities are the total, elastic and inelastic scattering, fission, capture, (n,2n), (n,3n) and (n,4n) reaction cross sections, the resolved and unresolved resonance parameters, the angular and energy distributions of emitted neutrons, and the average number of neutrons emitted per fission. The simultaneous evaluation method was adopted for the fission cross section so as to keep the consistency among the main fissile and fertile material nuclides. The theoretical calculations based on the spherical optical model and the statistical model were also used, when the experimental data were not sufficient. Discussion is given on the evaluation method. (author)

  20. Neutronics analysis of the conceptual design of a component test facility based on the spherical tokamak

    International Nuclear Information System (INIS)

    Zheng, S.; Voss, G.M.; Pampin, R.

    2010-01-01

    One of the crucial aspects of fusion research is the optimisation and qualification of suitable materials and components. To enable the design and construction of DEMO in the future, ITER is taken to demonstrate the scientific and technological feasibility and IFMIF will provide rigorous testing of small material samples. Meanwhile, a dedicated, small-scale components testing facility (CTF) is proposed to complement and extend the functions of ITER and IFMIF and operate in association with DEMO so as to reduce the risk of delays during this phase of fusion power development. The design of a spherical tokamak (ST)-based CTF is being developed which offers many advantages over conventional machines, including lower tritium consumption, easier maintenance, and a compact assembly. The neutronics analysis of this system is presented here. Based on a three-dimensional neutronics model generated by the interface programme MCAM from CAD models, a series of nuclear and radiation protection analyses were carried out using the MCNP code and FENDL2.1 nuclear data library to assess the current design and guide its development if needed. The nuclear analyses addresses key neutronics issues such as the neutron wall loading (NWL) profile, nuclear heat loads, and radiation damage to the coil insulation and to structural components, particularly the stainless steel vessel wall close to the NBI ports where shielding is limited. The shielding of the divertor coil and the internal Poloidal Field (PF) coil, which is introduced in the expanded divertor design, are optimised to reduce their radiation damage. The preliminary results show that the peak radiation damage to the structure of martensitic/ferritic steel is about 29 dpa at the mid-plane assuming a life of 12 years at a duty factor 33%, which is much lower than its ∼150 dpa limit. In addition, TBMs installed in 8 mid-plane ports and 6 lower ports, and 60% 6 Li enrichment in the Li 4 SiO 4 breeder, the total tritium generation is

  1. A new design of neutron survey instrument

    International Nuclear Information System (INIS)

    Tanner, R.J.; Eakins, J.S.; Hager, L.G.

    2010-01-01

    A novel design of neutron survey instrument has been developed. The moderator has been modified via the use of 'neutron guides', which help thermal neutrons reach the central proportional counter. This innovation has allowed the variations in the energy dependence of ambient dose equivalent response to be reduced compared to prior single-detector designs, whilst maintaining a relatively light moderator and simple construction. In particular, the design has a relatively small over-response to neutrons with energies around 5 keV, when compared to prior designs. The final optimized design has been verified using MCNP5 calculations to ensure that the response is relatively independent of the energy and direction of the incident neutron. This has required the ends of the guides to be structured so that unidirectional and isotropic neutron fields have closely matched responses, as is necessary in the workplace. The reading of the instrument in workplace fields is calculated via folding and the suitability of the design for use in the workplace discussed.

  2. Independent measuring station for the GNEJS neutron spectrometer information and measurement system

    International Nuclear Information System (INIS)

    Gorokhov, I.S.; Laptev, A.B.; Marchenkov, V.V.; Tubol'tsev, Yu.V.; Fokin, E.Yu.; Shcherbakov, O.A.

    1984-01-01

    An independent measuring station (IMS) being a part of the information and measuring system of the neutron time-of-flight spectrometer is described. IMS represents the time (time-to-amplitude or time-to-angular) module analyzer assembled on the base of one or several CAMAC crates. The station permits to perform time measurements as well as the time measurements with amplitude weighing in an independent mode with subseqUent data transmission the central PDP-11/05 computer. The station processor unit is an independent controller. The software consists of the programming langUage of the controller from local terminal and programs ensuring measuring and shaping the spectra with their output on TV display devic. communication with the computer and dialogue with the operator

  3. Glass-like, low-energy excitations in neutron-irradiated quartz

    International Nuclear Information System (INIS)

    Gardner, J.W.

    1980-01-01

    The specific heat and thermal conductivity of neutron-irradiated crystalline quartz have been measured for temperatures approx. = 0.1 to 5 K. Four types of low-energy excitations are observed in the irradiated samples, two of which can be removed selectively by heat treatment. One set of remaining excitations gives rise to low-temperature thermal behavior characteristic of glassy (amorphous) solids. The density of these glass-like excitations can be 50% the density observed in vitreous silica, yet the sample still retains long-range atomic order. In a less-irradiated sample, glass-like excitations may be present with a density only approx. = 2.5% that observed in vitreous silica and possess a similar broad energy spectrum over 0.1 to 1 K

  4. Implosion anisotropy of neutron kinetic energy distributions as measured with the neutron time-of-flight diagnostics at the National Ignition Facility

    Science.gov (United States)

    Hartouni, Edward; Eckart, Mark; Field, John; Grim, Gary; Hatarik, Robert; Moore, Alastair; Munro, David; Sayer, Daniel; Schlossberg, David

    2017-10-01

    Neutron kinetic energy distributions from fusion reactions are characterized predominantly by the excess energy, Q, of the fusion reaction and the variance of kinetic energy which is related to the thermal temperature of the plasma as shown by e.g. Brysk. High statistics, high quality neutron time-of-flight spectra obtained at the National Ignition Facility provide a means of measuring small changes to the neutron kinetic energy due to the spatial and temporal distribution of plasma temperature, density and velocity. The modifications to the neutron kinetic energy distribution as described by Munro include plasma velocity terms with spatial orientation, suggesting that the neutron kinetic energy distributions could be anisotropic when viewed by multiple lines-of-sight. These anisotropies provide a diagnostic of burn averaged plasma velocity distributions. We present the results of measurements made for a variety of DT implosions and discuss their possible physical interpretations. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC.

  5. Simulations of neutron transport at low energy: a comparison between GEANT and MCNP.

    Science.gov (United States)

    Colonna, N; Altieri, S

    2002-06-01

    The use of the simulation tool GEANT for neutron transport at energies below 20 MeV is discussed, in particular with regard to shielding and dose calculations. The reliability of the GEANT/MICAP package for neutron transport in a wide energy range has been verified by comparing the results of simulations performed with this package in a wide energy range with the prediction of MCNP-4B, a code commonly used for neutron transport at low energy. A reasonable agreement between the results of the two codes is found for the neutron flux through a slab of material (iron and ordinary concrete), as well as for the dose released in soft tissue by neutrons. These results justify the use of the GEANT/MICAP code for neutron transport in a wide range of applications, including health physics problems.

  6. Surface energy of very neutron rich nuclei

    CERN Document Server

    Von Groote, H

    1976-01-01

    For a microscopic model calculation of the nuclear surface-energy coefficient sigma the surface energy is defined as the energy loss of an uncharged, semiinfinite (inhomogeneous) two-component system compared to an infinite (homogeneous) system with the same particle asymmetry delta . Using the Thomas-Fermi model the calculations are performed for a series of systems with increasing delta , starting from symmetric matter ( delta =0) and extending beyond the drip line of the neutrons, until the system undergoes a phase transition to a homogeneous system. The results for the surface energy as well as for the neutron skin and for the surface diffuseness are compared to the macroscopic approach of the Droplet Model (DM), which turns out to be a good approximation for small asymmetries typical for the region of the valley of beta -stability. For larger asymmetries, close to the drip lines, terms of higher order than contained in the DM approach are no longer negligible. Beyond the drip lines the pressure of the ou...

  7. Testing Moderating Detection Systems with 252Cf-Based Reference Neutron Fields

    International Nuclear Information System (INIS)

    Hertel, Nolan E.; Sweezy, Jeremy; Sauber, Jeremiah S.; Vaughn, David; Cook, Andrew; Tays, Jeff; Ro, Tae-Ik

    2001-01-01

    Calibration measurements were carried out on a probe designed to measure ambient dose equivalent in accordance with ICRP Pub 60 recommendations. It consists of a cylindrical 3 He proportional counter surrounded by a 25-cm-diameter spherical polyethylene moderator. Its neutron response is optimized for dose rate measurements of neutrons between thermal energies and 20 MeV. The instrument was used to measure the dose rate in four separate neutron fields: unmoderated 252 Cf, D 2 O-moderated 252 Cf, polyethylene-moderated 252 Cf, and WEP neutron howitzer with 252 Cf at its center. Dose equivalent measurements were performed at source-detector centerline distances from 50 to 200 cm. The ratio of air-scatter- and room-return-corrected ambient dose equivalent rates to ambient dose equivalent rates calculated with the code MCNP are tabulated

  8. Direct capture of low-energy neutrons by {sup 16}O

    Energy Technology Data Exchange (ETDEWEB)

    Kitazawa, Hideo [Tokyo Inst. of Tech., Nagatsuta, Yokohama (Japan). Interdisciplinary Graduate School of Science; Igashira, Masayuki

    1998-03-01

    A dispersive optical potential for the interaction between low-energy neutrons and {sup 16}O-nuclei is derived from a dispersion relation based on the Feshbach generalized optical model. This potential is applied to direct-capture model calculations in explaining the observed off-resonance capture transitions to the ground (5/2{sup +}) and 871 keV(1/2{sup +}) levels in {sup 17}O at neutron energies of 20-70 keV. The model calculations take account of the spatial nonlocality of the neutron-nucleus interaction potential. (author)

  9. Average cross sections calculated in various neutron fields

    International Nuclear Information System (INIS)

    Shibata, Keiichi

    2002-01-01

    Average cross sections have been calculated for the reactions contained in the dosimetry files, JENDL/D-99, IRDF-90V2, and RRDF-98 in order to select the best data for the new library IRDF-2002. The neutron spectra used in the calculations are as follows: 1) 252 Cf spontaneous fission spectrum (NBS evaluation), 2) 235 U thermal fission spectrum (NBS evaluation), 3) Intermediate-energy Standard Neutron Field (ISNF), 4) Coupled Fast Reactivity Measurement Facility (CFRMF), 5) Coupled thermal/fast uranium and boron carbide spherical assembly (ΣΣ), 6) Fast neutron source reactor (YAYOI), 7) Experimental fast reactor (JOYO), 8) Japan Material Testing Reactor (JMTR), 9) d-Li neutron spectrum with a 2-MeV deuteron beam. The items 3)-7) represent fast neutron spectra, while JMTR is a light water reactor. The Q-value for the d-Li reaction mentioned above is 15.02 MeV. Therefore, neutrons with energies up to 17 MeV can be produced in the d-Li reaction. The calculated average cross sections were compared with the measurements. Figures 1-9 show the ratios of the calculations to the experimental data which are given. It is found from these figures that the 58 Fe(n, γ) cross section in JENDL/D-99 reproduces the measurements in the thermal and fast reactor spectra better than that in IRDF-90V2. (author)

  10. A prototype detector using the neutron image intensifier and multi-anode type photomultiplier tube for pulsed neutron imaging

    International Nuclear Information System (INIS)

    Ishikawa, Hirotaku; Sato, Hirotaka; Hara, Kaoru Y.; Kamiyama, Takashi

    2016-01-01

    We developed a neutron two-dimensional (2-D) detector for pulsed neutron imaging as a prototype detector, which was composed of a neutron image intensifier and a multi-anode type photomultiplier tube. A neutron transmission spectrum of α-Fe plate was measured by the prototype detector, and compared with the one measured by a typical neutron 2-D detector. The spectrum was in reasonable agreement with the one measured by the typical detector in the neutron wavelength region above 0.15 nm. In addition, a neutron transmission image of a cadmium indicator was obtained by the prototype detector. The usefulness of the prototype detector for pulsed neutron imaging was demonstrated. (author)

  11. Bench mark spectra for high-energy neutron dosimetry

    International Nuclear Information System (INIS)

    Dierckx, R.

    1986-01-01

    To monitor radiation damage experiments, activation detectors are commonly used. The precision of the results obtained by the multiple foil analysis is largely increased by the intercalibration in bench-mark spectra. This technique is already used in dosimetry measurements for fission reactors. To produce neutron spectra similar to fusion reactor and high-energy high-intensity neutron sources (d-Li or spallation), accelerators can be used. Some possible solutions as p-Be and d-D 2 O neutron sources, useful as bench-mark spectra are described. (author)

  12. Energy spectra of fast neutrons by nuclear emulsion method

    International Nuclear Information System (INIS)

    Quaresma, A.A.

    1977-01-01

    An experimental method which uses nuclear emulsion plates to determine the energy spectrum of fission neutrons is described. By using this technique, we have obtained the energy distribution of neutrons from spontaneous fission of Cf 2 5 2 . The results are in good agreement with whose obtained previously by others authors who have used different detection techniques, and they are consistent with a Maxwellian distribution as expected by Weisskopf's nuclear evaporation theory. (author)

  13. The world’s first pelletized cold neutron moderator at a neutron scattering facility

    Energy Technology Data Exchange (ETDEWEB)

    Ananiev, V.; Belyakov, A.; Bulavin, M.; Kulagin, E.; Kulikov, S.; Mukhin, K.; Petukhova, T.; Sirotin, A.; Shabalin, D.; Shabalin, E.; Shirokov, V.; Verhoglyadov, A., E-mail: verhoglyadov_al@mail.ru

    2014-02-01

    In July 10, 2012 cold neutrons were generated for the first time with the unique pelletized cold neutron moderator CM-202 at the IBR-2M reactor. This new moderator system uses small spherical beads of a solid mixture of aromatic hydrocarbons (benzene derivatives) as the moderating material. Aromatic hydrocarbons are known as the most radiation-resistant hydrogenous substances and have properties to moderate slow neutrons effectively. Since the new moderator was put into routine operation in September 2013, the IBR-2 research reactor of the Frank Laboratory of Neutron Physics has consolidated its position among the world’s leading pulsed neutron sources for investigation of matter with neutron scattering methods.

  14. An optical potential for the statically deformed actinide nuclei derived from a global spherical potential

    Science.gov (United States)

    Al-Rawashdeh, S. M.; Jaghoub, M. I.

    2018-04-01

    In this work we test the hypothesis that a properly deformed spherical optical potential, used within a channel-coupling scheme, provides a good description for the scattering data corresponding to neutron induced reactions on the heavy, statically deformed actinides and other lighter deformed nuclei. To accomplish our goal, we have deformed the Koning-Delaroche spherical global potential and then used it in a channel-coupling scheme. The ground-state is coupled to a sufficient number of inelastic rotational channels belonging to the ground-state band to ensure convergence. The predicted total cross sections, elastic and inelastic angular distributions are in good agreement with the experimental data. As a further test, we compare our results to those obtained by a global channel-coupled optical model whose parameters were obtained by fitting elastic and inelastic angular distributions in addition to total cross sections. Our results compare quite well with those obtained by the fitted, channel-coupled optical model. Below neutron incident energies of about 1MeV, our results show that scattering into the rotational excited states of the ground-state band plays a significant role in the scattering process and must be explicitly accounted for using a channel-coupling scheme.

  15. Recent developments in very low energy neutron technology

    International Nuclear Information System (INIS)

    Utsuro, Masahiko; Kawabata, Yuji; Yamaguchi, Akira; Yoshiki, Hajime.

    1993-01-01

    In this report, the recent state of the research and technical development of the neutrons in the energy region below 0.5 meV is introduced. The neutrons in this region are further divided into very cold neutrons (VCN) and ultracold neutrons (UCN). The UCNs are known by such characteristic behavior that they can be confined in a neutron bottle for long time. The attempt to verify the break of T conversion symmetry using neutrons is carried out. The experiment to show the break of T conversion symmetry by grasping the asymmetry of particle emission accompanying the beta decay of polarized neutrons is conceivable. In these cases, the use of UCNs in neutron bottles is effective. The optical properties of VCNs and UCNs are peculiar and resemble to those of light. The only VCN source in Japan is installed in the liquid deuterium CN source in the graphite facility of the KUR. VCNs are taken out from the reactor, and are converted to UCNs using a neutron turbine. The characteristics of an UCN bottle were measured, and the life of neutrons was determined as 887.6 ± 3s. The UCN experiment using superfluid helium was carried out, and the application of gravity to UCN spectrometry was developed as NESSIE. (K.I.)

  16. Neutron activation analysis applied to energy and environment

    International Nuclear Information System (INIS)

    Lyon, W.S.

    1975-01-01

    Neutron activation analysis was applied to a number of problems concerned with energy production and the environment. Burning of fossil fuel, the search for new sources of uranium, possible presence of toxic elements in food and water, and the relationship of trace elements to cardiovascular disease are some of the problems in which neutron activation was used. (auth)

  17. Superconducting superfluids in neutron stars

    International Nuclear Information System (INIS)

    Carter, B.

    2002-01-01

    For treatment of the layers below the crust of a neutron star it is useful to employ a relativistic model involving three independently moving constituents, representing superfluid neutrons, superfluid protons, and degenerate negatively charged leptons. A Kalb-Ramond type formulation is used here to develop such a model for the specific purpose of application at the semi macroscopic level characterised by lengthscales that are long compared with the separation between the highly localised and densely packed proton vortices of the Abrikosov type lattice that carries the main part of the magnetic flux, but that are short compared with the separation between the neutron vortices. (orig.)

  18. Induction heating of a spherical aluminum moderator vessel for the Advanced Neutron Source (ANS)

    International Nuclear Information System (INIS)

    Yousuf, A.

    1994-01-01

    This task was to identify and design a heating system to apply 15 kW of heat to a cold source vessel to simulate the Advanced Neutron Source reactor. This research project aims at the analysis of the induction heating of a spherical aluminum moderator vessel. Computer modeling is presented for the design and analysis of the induction heating system. The objective is to apply 15 kW of heat as uniformly as possible to the outer wall of a 410 mm diameter sphere of thickness 1.5 mm. The report also aims at the analysis of a system model which is simulated using the Eddycuff electromagnetic software. The computer model is built with the finite element analysis software Patran. The induction heating system analysis shows that the predicted performance is in close agreement with the computer simulated data. Hardware constraints such as power supplies and matching load are also analyzed in terms of performance and cost. Physical modeling is also suggested, in which the coil and the workpiece are scaled down

  19. Exciton binding energy in GaAsBiN spherical quantum dot heterostructures

    Science.gov (United States)

    Das, Subhasis; Dhar, S.

    2017-03-01

    The ground state exciton binding energies (EBE) of heavy hole excitons in GaAs1-x-yBixNy - GaAs spherical quantum dots (QD) are calculated using a variational approach under 1s hydrogenic wavefunctions within the framework of effective mass approximation. Both the nitrogen and the bismuth content in the material are found to affect the binding energy, in particular for larger nitrogen content and lower dot radii. Calculations also show that the ground state exciton binding energies of heavy holes increase more at smaller dot sizes as compared to that for the light hole excitons.

  20. Development and characterization of real-time wide-energy range personal neutron dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Takashi; Tsujimura, Norio (Tohoku Univ., Sendai (Japan). Cyclotron and Radioisotope Center); Yamano, Toshiya; Suzuki, Toshikazu; Okamoto, Eisuke

    1994-04-01

    The authors developed a real-time personal neutron dosimeter which could give neutron dose equivalent over wide energy region from thermal to 10 odd MeV by using 2 silicon detectors, fast neutron sensor and slow neutron sensor. The energy response of this dosimeter was evaluated under thermal neutron field, monoenergetic neutron field between 200 keV and 15 MeV, and moderated [sup 252]Cf neutron field. The neutron dose equivalent was estimated by adding neutron dose equivalent below 1 MeV given by slow neutron sensor and that above 1 MeV by fast neutron sensor. It was verified from various field tests that this dosimeter is able to give neutron dose equivalent within a factor of 2 margin of accuracy in reactor, accelerator, fusion research and nuclear fuel handling facilities. This dosimeter has more than one order higher sensitivity than conventional personal neutron dosimeters and is insensitive to [gamma]-rays up to about 500 mSv/h. This dosimeter will soon be commercially available as a personal dosimeter which gives neutron and [gamma]-ray dose equivalents simultaneously by installing [gamma]-ray silicon sensor. (author).

  1. Integrals of products of spherical functions

    International Nuclear Information System (INIS)

    Veverka, O.

    1975-01-01

    Various branches of mathematical physics use integral formulas of the products of spherical functions. In quantum mechanics and in transport theory the integrals ∫sub((4π))dΩ vectorYsub(s)sup(t)(Ω vector)Ysub(l)sup(k)(Ω vector)Ysub(n)sup(m)(Ω vector), ∫sub(-1)sup(1)dμPsub(s)sup(t)(μ)Psub(l)sup(k)(μ)Psub(n)sup(m)(μ), ∫sub(-1)sup(1)dμPsub(s)(μ)Psub(l)(μ)Psub(n)(μ) are generally applied, where Ysub(α)sup(β)(Ω vector) are spherical harmonics, Psub(α)sup(β)(μ) are associated Legendre functions, and Psub(α)(μ) are Legendre polynomials. In the paper, the general procedure of calculating the integrals of the products of any combination of spherical functions is given. The procedure is referred to in a report on the boundary conditions for the cylindrical geometry in neutron transport theory for both the outer and inner cylindrical boundaries. (author)

  2. Energy-resolved fast neutron resonance radiography at CSNS

    Science.gov (United States)

    Tan, Zhixin; Tang, Jingyu; Jing, Hantao; Fan, Ruirui; Li, Qiang; Ning, Changjun; Bao, Jie; Ruan, Xichao; Luan, Guangyuan; Feng, Changqin; Zhang, Xianpeng

    2018-05-01

    The white neutron beamline at the China Spallation Neutron Source will be used mainly for nuclear data measurements. It will be characterized by high flux and broad energy spectra. To exploit the beamline as a neutron imaging source, we propose a liquid scintillator fiber array for fast neutron resonance radiography. The fiber detector unit has a small exposed area, which will limit the event counts and separate the events in time, thus satisfying the requirements for single-event time-of-flight (SEToF) measurement. The current study addresses the physical design criteria for ToF measurement, including flux estimation and detector response. Future development and potential application of the technology are also discussed.

  3. Energy dependence of the optical model of neutron scattering from niobium

    International Nuclear Information System (INIS)

    Smith, A.B.; Guenther, P.T.; Lawson, R.D.

    1985-05-01

    Neutron differential-elastic-scattering cross sections of niobium were measured from 1.5 to 10.0 MeV at intervals of less than or equal to200 keV below 4.0 MeV, and of approx. =500 keV from 4.0 to 10.0 MeV. Ten to more than fifty differential-cross-section values were determined at each incident energy, distributed over the angular range approx. =20 to 160 0 . The observed values were interpreted in the context of the spherical optical-statistical model. It was found that the volume integral of the real potential decreased with energy whereas the integral of the imaginary part increased. The energy dependence in both cases was consistent with a linear variation. There is a dispersion relationship between the real and imaginary potentials, and when this was used, in conjunction with the experimental imaginary potential, it was possible to predict the observed energy dependence of the real potential to a good degree of accuracy, thus supporting the consistency of the data and its analysis. The real-potential well depths needed to give the correct binding energies of the 2d/sub 5/2/, 3s/sub 1/2/, 2d/sub 3/2/ and 1g/sub 7/2/ particle states and of the 1g/sub 9/2/ hole state are in reasonable agreement with those given by a linear extrapolation of the scattering potential. However, the well depths needed to give the observed binding of the 2p/sub 3/2/, 1f/sub 5/2/ and 2p/sub 1/2/ hole states are about 10% less than the extrapolated values. 40 refs., 5 figs

  4. Single event upset and charge collection measurements using high energy protons and neutrons

    International Nuclear Information System (INIS)

    Normand, E.; Oberg, D.L.; Wert, J.L.; Ness, J.D.; Majewski, P.P.; Wender, S.; Gavron, A.

    1994-01-01

    RAMs, microcontrollers and surface barrier detectors were exposed to beams of high energy protons and neutrons to measure the induced number of upsets as well as energy deposition. The WNR facility at Los Alamos provided a neutron spectrum similar to that of the atmospheric neutrons. Its effect on devices was compared to that of protons with energies of 200, 400, 500, and 800 MeV. Measurements indicate that SEU cross sections for 400 MeV protons are similar to those induced by the atmospheric neutron spectrum

  5. Response function measurement of plastic scintillator for high energy neutrons

    International Nuclear Information System (INIS)

    Sanami, Toshiya; Ban, Syuichi; Takahashi, Kazutoshi; Takada, Masashi

    2003-01-01

    The response function and detection efficiency of 2''φ x 2''L plastic (PilotU) and NE213 liquid (2''NE213) scintillators, which were used for the measurement of secondary neutrons from high energy electron induced reactions, were measured at Heavy Ion Medical Accelerator in Chiba (HIMAC). High energy neutrons were produced via 400 MeV/n C beam bombardment on a thick graphite target. The detectors were placed at 15 deg with respect to C beam axis, 5 m away from the target. As standard, a 5''φ x 5''L NE213 liquid scintillator (5''NE213) was also placed at same position. Neutron energy was determined by the time-of-flight method with the beam pickup scintillator in front of the target. In front of the detectors, veto scintillators were placed to remove charged particle events. All detector signals were corrected with list mode event by event. We deduce neutron spectrum for each detectors. The efficiency curves for pilotU and 2''NE213 were determined on the bases of 5 N E213 neutron spectrum and its efficiency calculated by CECIL code. (author)

  6. Synthesis of Hollow Silver Spheres using Spherical Vaterite-type Calcium Carbonate as Template

    Energy Technology Data Exchange (ETDEWEB)

    Park, Minyoung; Go, Hani; Kim, Jae-Hyun; Rhee, Seog Woo [Kongju National University, Kongju (Korea, Republic of)

    2016-03-15

    In this work, we describe the synthesis of hollow silver spheres using vaterite-type CaCO{sub 3} as template. The spherical vaterite-type CaCO{sub 3} was selectively precipitated d reaction of aqueous CaCl{sub 2} and Na{sub 2}CO{sub 3} in the presence of the polyelectrolyte poly(4-styrenesulfonate). Aqueous AgNO{sub 3} solution containing NH{sub 2}-functionalized CaCO{sub 3} particles was treated with reducing agents such as ascorbic acid, NaBH{sub 4}, and acetaldehyde, and the reduced silver particles were deposited on the surface of CaCO{sub 3}particles to form uniform silvershells. The CaCO{sub 3} used as template was removed from the CaCO{sub 3}/Ag composite by treatment with acid. Finally, the hollow silver sphere was obtained. The morphologies of product were investigated using electron microscopy, the chemical composition of the composite was analyzed using energy-dispersive X-ray spectroscopy, the vibration modes of the carbonate ion were investigated by Fourier transform infrared spectroscopy, the thermal mass change was measured using the thermogravimetric analysis, and the solid phases were confirmed by powder X-ray diffraction.

  7. Realistic electrostatic potentials in a neutron star crust

    International Nuclear Information System (INIS)

    Ebel, Claudio; Mishustin, Igor; Greiner, Walter

    2015-01-01

    We study the electrostatic properties of inhomogeneous nuclear matter which can be formed in the crusts of neutron stars or in supernova explosions. Such matter is represented by Wigner–Seitz cells of different geometries (spherical, cylindrical, cartesian), which contain nuclei, free neutrons and electrons under the conditions of electrical neutrality. Using the Thomas–Fermi approximation, we have solved the Poisson equation for the electrostatic potential and calculated the corresponding electron density distributions in individual cells. The calculations are done for different shapes and sizes of the cells and different average baryon densities. The electron-to-baryon fraction was fixed at 0.3. Using realistic electron distributions leads to a significant reduction in electrostatic energy and electron chemical potential. (paper)

  8. On the implementation of the spherical collapse model for dark energy models

    Energy Technology Data Exchange (ETDEWEB)

    Pace, Francesco [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL (United Kingdom); Meyer, Sven; Bartelmann, Matthias, E-mail: francesco.pace@manchester.ac.uk, E-mail: sven.meyer@uni-heidelberg.de, E-mail: bartelmann@uni-heidelberg.de [Zentrum für Astronomie der Universität Heidelberg, Institut für theoretische Astrophysik, Philosophenweg 12, D-69120, Heidelberg (Germany)

    2017-10-01

    In this work we review the theory of the spherical collapse model and critically analyse the aspects of the numerical implementation of its fundamental equations. By extending a recent work by [1], we show how different aspects, such as the initial integration time, the definition of constant infinity and the criterion for the extrapolation method (how close the inverse of the overdensity has to be to zero at the collapse time) can lead to an erroneous estimation (a few per mill error which translates to a few percent in the mass function) of the key quantity in the spherical collapse model: the linear critical overdensity δ{sub c}, which plays a crucial role for the mass function of halos. We provide a better recipe to adopt in designing a code suitable to a generic smooth dark energy model and we compare our numerical results with analytic predictions for the EdS and the ΛCDM models. We further discuss the evolution of δ{sub c} for selected classes of dark energy models as a general test of the robustness of our implementation. We finally outline which modifications need to be taken into account to extend the code to more general classes of models, such as clustering dark energy models and non-minimally coupled models.

  9. On the implementation of the spherical collapse model for dark energy models

    Science.gov (United States)

    Pace, Francesco; Meyer, Sven; Bartelmann, Matthias

    2017-10-01

    In this work we review the theory of the spherical collapse model and critically analyse the aspects of the numerical implementation of its fundamental equations. By extending a recent work by [1], we show how different aspects, such as the initial integration time, the definition of constant infinity and the criterion for the extrapolation method (how close the inverse of the overdensity has to be to zero at the collapse time) can lead to an erroneous estimation (a few per mill error which translates to a few percent in the mass function) of the key quantity in the spherical collapse model: the linear critical overdensity δc, which plays a crucial role for the mass function of halos. We provide a better recipe to adopt in designing a code suitable to a generic smooth dark energy model and we compare our numerical results with analytic predictions for the EdS and the ΛCDM models. We further discuss the evolution of δc for selected classes of dark energy models as a general test of the robustness of our implementation. We finally outline which modifications need to be taken into account to extend the code to more general classes of models, such as clustering dark energy models and non-minimally coupled models.

  10. A Study of Neutron Leakage in Finite Objects

    Science.gov (United States)

    Wilson, John W.; Slaba, Tony C.; Badavi, Francis F.; Reddell, Brandon D.; Bahadori, Amir A.

    2015-01-01

    A computationally efficient 3DHZETRN code capable of simulating High charge (Z) and Energy (HZE) and light ions (including neutrons) under space-like boundary conditions with enhanced neutron and light ion propagation was recently developed for simple shielded objects. Monte Carlo (MC) benchmarks were used to verify the 3DHZETRN methodology in slab and spherical geometry, and it was shown that 3DHZETRN agrees with MC codes to the degree that various MC codes agree among themselves. One limitation in the verification process is that all of the codes (3DHZETRN and three MC codes) utilize different nuclear models/databases. In the present report, the new algorithm, with well-defined convergence criteria, is used to quantify the neutron leakage from simple geometries to provide means of verifying 3D effects and to provide guidance for further code development.

  11. Neutron-proton bremsstrahlung from intermediate energy heavy-ion reactions as a probe of the nuclear symmetry energy?

    International Nuclear Information System (INIS)

    Yong, G.-C.; Li Baoan; Chen Liewen

    2008-01-01

    Hard photons from neutron-proton bremsstrahlung in intermediate energy heavy-ion reactions are examined as a potential probe of the nuclear symmetry energy within a transport model. Effects of the symmetry energy on the yields and spectra of hard photons are found to be generally smaller than those due to the currently existing uncertainties of both the in-medium nucleon-nucleon cross sections and the photon production probability in the elementary process pn→pnγ. Very interestingly, nevertheless, the ratio of hard photon spectra R 1/2 (γ) from two reactions using isotopes of the same element is not only approximately independent of these uncertainties but also quite sensitive to the symmetry energy. For the head-on reactions of 132 Sn + 124 Sn and 112 Sn + 112 Sn at E beam /A=50 MeV, for example, the R 1/2 (γ) displays a rise up to 15% when the symmetry energy is reduced by about 20% at ρ=1.3ρ 0 which is the maximum density reached in these reactions

  12. Neutron yield from thick lead target by the action of high-energy electrons

    International Nuclear Information System (INIS)

    Noga, V.I.; Ranyuk, Yu.N.; Telegin, Yu.N.; Sorokin, P.V.

    1978-01-01

    The results are presented of studying the complete neutron yield from a lead target bombarded by high-energy electrons. Neutrons were recorded by the method of radio-active indicators. The dependence of the neutron yield on the target thickness varying from 0.2 to 8 cm was obtained at the energies of electrons of 230 and 1200 MeV. The neutron yield for the given energies with the target of 6 cm in thickness is in the range of saturation and is 0.1 +-0.03 and 0.65+-0.22 (neutr./MeV.el.), respectively. The neutron angular distributions were measured for different thicknesses of targets at the 201, 230 and 1200 MeV electrons. Within the error limits the angular distributions are isotropic. The dependence of neutron yield on the electron energy was examined for a 3 cm thick target. In the energy range of 100-1200 MeV these values are related by a linear dependence with the proportionality coefficient C=3x10 -4 (neutr./MeV.el.)

  13. Application of neutron transmutation doping method to initially p-type silicon material.

    Science.gov (United States)

    Kim, Myong-Seop; Kang, Ki-Doo; Park, Sang-Jun

    2009-01-01

    The neutron transmutation doping (NTD) method was applied to the initially p-type silicon in order to extend the NTD applications at HANARO. The relationship between the irradiation neutron fluence and the final resistivity of the initially p-type silicon material was investigated. The proportional constant between the neutron fluence and the resistivity was determined to be 2.3473x10(19)nOmegacm(-1). The deviation of the final resistivity from the target for almost all the irradiation results of the initially p-type silicon ingots was at a range from -5% to 2%. In addition, the burn-up effect of the boron impurities, the residual (32)P activity and the effect of the compensation characteristics for the initially p-type silicon were studied. Conclusively, the practical methodology to perform the neutron transmutation doping of the initially p-type silicon ingot was established.

  14. Temperature-independent sensors based on perovskite-type oxides

    International Nuclear Information System (INIS)

    Zaza, F.; Frangini, S.; Masci, A.; Leoncini, J.; Pasquali, M.; Luisetto, I.; Tuti, S.

    2013-01-01

    The need of energy security and environment sustainability drives toward the development of energy technology in order to enhance the performance of internal combustion engines. Gas sensors play a key role for controlling the fuel oxygen ratio and monitoring the pollution emissions. The perovskite-type oxides can be synthesized for an extremely wide variety of combinations of chemical elements, allowing to design materials with suitable properties for sensing application. Lanthanum strontium ferrites, such as La 0.7 Sr 0.3 FeO 3 , are suitable oxygen sensing materials with temperature-independence conductivity, but they have low chemical stability under reducing conditions. The addition of aluminum into the perovskite structure improves the material properties in order to develop suitable oxygen sensing probes for lean burn engine control systems. Perovskite-type oxides with formula (La 0.7 Sr 0.3 )(Al x Fe 1−x )O 3 was synthesized by the citrate-nitrate combustion synthesis method. XRD analyses, show that it was synthesized a phase-pure powder belonging to the perovskite structure. Aluminum affects both the unit cell parameters, by shrinking the unit cell, and the powder morphology, by promoting the synthesis of particles with small crystallite size and large specific surface area. The partial substitution of iron with aluminum improves the chemical stability under reducing gas conditions and modulates the oxygen sensitivity by affecting the relative amount of Fe 4+ and Fe 3+ , as confirmed from TPR profiles. In the same time, the addition of aluminum does not affects the temperature-independent properties of lanthanum strontium ferrites. Indeed, the electrical measurements show that (La 0.7 Sr 0.3 )(Al x Fe 1−x )O 3 perovskites have temperature-independence conductivity from 900 K

  15. Temperature-independent sensors based on perovskite-type oxides

    Energy Technology Data Exchange (ETDEWEB)

    Zaza, F.; Frangini, S.; Masci, A. [ENEA-Casaccia R.C., Via Anguillarese 301, 00123 S.Maria di Galeria, Rome (Italy); Leoncini, J.; Pasquali, M. [University La Sapienza, Piazza Via del Castro Laurenziano 7, 00161 Rome (Italy); Luisetto, I.; Tuti, S. [University RomaTre, Rome 00146 (Italy)

    2014-06-19

    The need of energy security and environment sustainability drives toward the development of energy technology in order to enhance the performance of internal combustion engines. Gas sensors play a key role for controlling the fuel oxygen ratio and monitoring the pollution emissions. The perovskite-type oxides can be synthesized for an extremely wide variety of combinations of chemical elements, allowing to design materials with suitable properties for sensing application. Lanthanum strontium ferrites, such as La{sub 0.7}Sr{sub 0.3}FeO{sub 3}, are suitable oxygen sensing materials with temperature-independence conductivity, but they have low chemical stability under reducing conditions. The addition of aluminum into the perovskite structure improves the material properties in order to develop suitable oxygen sensing probes for lean burn engine control systems. Perovskite-type oxides with formula (La{sub 0.7}Sr{sub 0.3})(Al{sub x}Fe{sub 1−x})O{sub 3} was synthesized by the citrate-nitrate combustion synthesis method. XRD analyses, show that it was synthesized a phase-pure powder belonging to the perovskite structure. Aluminum affects both the unit cell parameters, by shrinking the unit cell, and the powder morphology, by promoting the synthesis of particles with small crystallite size and large specific surface area. The partial substitution of iron with aluminum improves the chemical stability under reducing gas conditions and modulates the oxygen sensitivity by affecting the relative amount of Fe{sup 4+} and Fe{sup 3+}, as confirmed from TPR profiles. In the same time, the addition of aluminum does not affects the temperature-independent properties of lanthanum strontium ferrites. Indeed, the electrical measurements show that (La{sub 0.7}Sr{sub 0.3})(Al{sub x}Fe{sub 1−x})O{sub 3} perovskites have temperature-independence conductivity from 900 K.

  16. Nuclear polarization and neutrons

    International Nuclear Information System (INIS)

    Glaettli, H.

    1985-01-01

    Different possibilities for the use of polarized nuclei in thermal neutron scattering on condensed matter are reviewed. Highly polarized nuclei are the starting point for studying dipolar magnetic order. Systematic measurement of spin-dependent scattering lengths is possible on samples with polarized nuclei. Highly polarized hydrogen should help to unravel complicated structures in chemistry and biology. The use of polarized proton targets as an energy-independent neutron polarizer in the thermal and epithermal region should be considered afresh. (author)

  17. RE-EVALUATION OF THE NEUTRON EMISSION FROM THE SOLAR FLARE OF 2005 SEPTEMBER 7, DETECTED BY THE SOLAR NEUTRON TELESCOPE AT SIERRA NEGRA

    Energy Technology Data Exchange (ETDEWEB)

    González, L. X. [SCiESMEX, Instituto de Geofísica Unidad Michoacán, Universidad Nacional Autónoma de México, 58190, Morelia, Michoacán (Mexico); Valdés-Galicia, J. F.; Musalem, O.; Hurtado, A. [Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, 04510, D. F. Mexico (Mexico); Sánchez, F. [Instituto de Tecnologías en Detección de Astropartículas, Comisión Nacional de Energía Atómica, 1429, Buenos Aires (Argentina); Muraki, Y.; Sako, T.; Matsubara, Y.; Nagai, Y. [Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Watanabe, K. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Yoshinodai, chuo-ku, Sagamihara 252-5210 (Japan); Shibata, S. [College of Engineering, Chubu University, Kasugai, Aichi 487-8501 (Japan); Sakai, T. [College of Industrial Technologies, Nihon University, Narashino 275-0005 (Japan)

    2015-12-01

    The X17.0 solar flare of 2005 September 7 released high-energy neutrons that were detected by the Solar Neutron Telescope (SNT) at Sierra Negra, Mexico. In three separate and independent studies of this solar neutron event, several of its unique characteristics were studied; in particular, a power-law energy spectra was estimated. In this paper, we present an alternative analysis, based on improved numerical simulations of the detector using GEANT4, and a different technique for processing the SNT data. The results indicate that the spectral index that best fits the neutron flux is around 3, in agreement with previous works. Based on the numerically calculated neutron energy deposition on the SNT, we confirm that the detected neutrons might have reached an energy of 1 GeV, which implies that 10 GeV protons were probably produced; these could not be observed at Earth, as their parent flare was an east limb event.

  18. Phases of dense matter with non-spherical nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Pethick, C J [NORDITA, Copenhagen (Denmark); [Dept. of Physics, Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States); Ravenhall, D G [Dept. of Physics, Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States)

    1998-06-01

    A brief review is given of some of the important physics related to phases with non-spherical nuclei that can exist in neutron stars and in matter in stellar collapse at densities just below the saturation density of nuclear matter. Comparisons are made with other systems that exhibit similar liquid-crystal-like phases, both in nuclear physics and in condensed matter physics. A short account is given of recent work on the elastic properties of these phases, and their vibration spectrum, as well as on neutron superfluid gaps. (orig.)

  19. Spatial distribution of moderated neutrons along a Pb target irradiated by high-energy protons

    International Nuclear Information System (INIS)

    Fragopoulou, M.; Manolopoulou, M.; Stoulos, S.; Brandt, R.; Westmeier, W.; Kulakov, B.A.; Krivopustov, M.I.; Sosnin, A.N.; Debeauvais, M.; Adloff, J.C.; Zamani Valasiadou, M.

    2006-01-01

    High-energy protons in the range of 0.5-7.4 GeV have irradiated an extended Pb target covered with a paraffin moderator. The moderator was used in order to shift the hard Pb spallation neutron spectrum to lower energies and to increase the transmutation efficiency via (n,γ) reactions. Neutron distributions along and inside the paraffin moderator were measured. An analysis of the experimental results was performed based on particle production by high-energy interactions with heavy targets and neutron spectrum shifting by the paraffin. Conclusions about the spallation neutron production in the target and moderation through the paraffin are presented. The study of the total neutron fluence on the moderator surface as a function of the proton beam energy shows that neutron cost is improved up to 1 GeV. For higher proton beam energies it remains constant with a tendency to decline

  20. First observations of power MOSFET burnout with high energy neutrons

    International Nuclear Information System (INIS)

    Oberg, D.L.; Wert, J.L.; Normand, E.; Majewski, P.P.; Wender, S.A.

    1996-01-01

    Single event burnout was seen in power MOSFETs exposed to high energy neutrons. Devices with rated voltage ≥400 volts exhibited burnout at substantially less than the rated voltage. Tests with high energy protons gave similar results. Burnout was also seen in limited tests with lower energy protons and neutrons. Correlations with heavy-ion data are discussed. Accelerator proton data gave favorable comparisons with burnout rates measured on the APEX spacecraft. Implications for burnout at lower altitudes are also discussed

  1. Constraints on the symmetry energy from neutron star observations

    International Nuclear Information System (INIS)

    Newton, W G; Gearheart, M; Wen, De-Hua; Li, Bao-An

    2013-01-01

    The modeling of many neutron star observables incorporates the microphysics of both the stellar crust and core, which is tied intimately to the properties of the nuclear matter equation of state (EoS). We explore the predictions of such models over the range of experimentally constrained nuclear matter parameters, focusing on the slope of the symmetry energy at nuclear saturation density L. We use a consistent model of the composition and EoS of neutron star crust and core matter to model the binding energy of pulsar B of the double pulsar system J0737-3039, the frequencies of torsional oscillations of the neutron star crust and the instability region for r-modes in the neutron star core damped by electron-electron viscosity at the crust-core interface. By confronting these models with observations, we illustrate the potential of astrophysical observables to offer constraints on poorly known nuclear matter parameters complementary to terrestrial experiments, and demonstrate that our models consistently predict L < 70 MeV.

  2. Pixel pitch and particle energy influence on the dark current distribution of neutron irradiated CMOS image sensors.

    Science.gov (United States)

    Belloir, Jean-Marc; Goiffon, Vincent; Virmontois, Cédric; Raine, Mélanie; Paillet, Philippe; Duhamel, Olivier; Gaillardin, Marc; Molina, Romain; Magnan, Pierre; Gilard, Olivier

    2016-02-22

    The dark current produced by neutron irradiation in CMOS Image Sensors (CIS) is investigated. Several CIS with different photodiode types and pixel pitches are irradiated with various neutron energies and fluences to study the influence of each of these optical detector and irradiation parameters on the dark current distribution. An empirical model is tested on the experimental data and validated on all the irradiated optical imagers. This model is able to describe all the presented dark current distributions with no parameter variation for neutron energies of 14 MeV or higher, regardless of the optical detector and irradiation characteristics. For energies below 1 MeV, it is shown that a single parameter has to be adjusted because of the lower mean damage energy per nuclear interaction. This model and these conclusions can be transposed to any silicon based solid-state optical imagers such as CIS or Charged Coupled Devices (CCD). This work can also be used when designing an optical imager instrument, to anticipate the dark current increase or to choose a mitigation technique.

  3. Fast-neutron elastic scattering from elemental vanadium

    International Nuclear Information System (INIS)

    Smith, A.B.; Guenther, P.T.; Lawson, R.D.

    1988-03-01

    Differential neutron elastic- and inelastic-scattering cross sections of vanadium were measured from 4.5 to 10 MeV. These results were combined with previous 1.5 to 4.0 MeV data from this laboratory, the 11.1 MeV elastic-scattering results obtained at Ohio University, and the reported neutron total cross sections to energies of ∼20.0 MeV, to form a data base which was interpreted in terms of the spherical optical-statistical model. A fit to the data was achieved by making both the strengths and geometries of the optical-model potential energy dependent. This energy dependence was large below ∼6.0 MeV. Above ∼6.0 MeV the energy dependencies are smaller, and similar to those characteristic of global models. Using the dispersion relationship and the method of moments, the optical-model potential energy deduced from 0.0 to 11.1 MeV neutron-scattering data was extrapolated to higher energies and to the bound-state regime. This extrapolation leads to predicted neutron total cross sections that are within 3% of the experimental values throughout the energy range 0.0 to 20.0 MeV. Furthermore, the values of the volume-integral-per-nucleon of the real potential are in excellent agreement with those needed to reproduce the observed binding energies of particle- and hole-states. The latter gives clear evidence of the Fermi surface anomaly. Using only the 0.0 to 11.1 MeV data, the predicted E < O behavior of the strength and radius of the real shell-model Woods-Saxon potential are somewhat different from those obtained by Mahaux and Sartor in their analysis of nuclei near closed shells. 61 refs., 9 figs., 2 tabs

  4. ANISN-FONTENAY, 1-D Planar, Spherical, Cylindrical Neutron Transport and Gamma Transport with Deep Penetration

    International Nuclear Information System (INIS)

    Devillers, C.

    1973-01-01

    1 - Nature of physical problem solved: The ANISN system treats neutron and gamma transport in one-dimensional plane, spherical and cylinder geometry. The multigroup cross sections prepared by the programs LIANE and SUPERTOG are processed by the program RETTOG, which produces a binary library with Legendre expansions. The binary library can be updated and edited with the program LGR/B. The photon multigroup cross sections are created with the program GAMLEG/A. If the bulk of the data is too large, the program TAPEMA produces a special group-by-group library. The volume sources are calculated from a reduced set of input data and punched in a format suitable for input to ANISN, using the program PRESOU. The program ANISN calculates fluxes by groups, space intervals, angle and any number of reaction rates. The energy and space dependent fluxes are stored on tape and can be reprocessed, edited and plotted with the program ANISEX, which also permits to calculate supplementary reaction rates. The program ANISN can condense cross sections into a reduced number of groups. The ANISN system is used as a reference system for the evaluation of approximation methods (space-diffusion or point- kernel) or for the preparation of multigroup libraries for 2- dimensional transport codes (DOT). In particular it is used for shielding problems with high attenuation in water reactors and fast reactors. 2 - Method of solution: Method of discrete ordinates. The program has been designed to treat deep penetration with detailed calculation of spectrum as function of angle. Tests for pointwise convergence have also been introduced. 3 - Restrictions on the complexity of the problem: The complexity of the problem is limited by the storage size

  5. Differential neutron spectrometry in the very low neutron energy range. Neutron cross sections for Zr, Al, polyethylene and liquid fluoropolymers

    International Nuclear Information System (INIS)

    Pokotilovskij, Yu.N.; Novopol'tsev, M.I.; Geltenbort, P.; Brenner, T.

    2003-01-01

    Some results of the test of the time-of-flight neutron spectrometers in the energy range (0.05-2.5)μeV are described. The measurements of total and differential cross sections were performed for several substances relevant to the experiments in the physics of ultracold neutrons: Zr, Al, polyethylene and liquid fluoropolymers

  6. Photon and neutron energy response of Thermoluminescent (TL) dosimeters

    International Nuclear Information System (INIS)

    Thilagam, L.; Priya, M.R.; Mohapatra, D.K.

    2018-01-01

    Theoretical Monte Carlo (MC) simulations are carried out to investigate the relative thermoluminesence (TL) response of the most commonly used TLD materials to a wide range of photon energy. The effect of polytetrafluoroethylene (PTFE) on TL response of CaSO 4 :Dy is also studied. Additionally, the neutron response of LiF:Mg,Ti TL materials with different concentrations of 6 Li is estimated in terms of the number of 6 Li(n, t) 4 He capture reactions for a wider neutron energy

  7. Neutron spectroscopy measurements of 14 MeV neutrons at unprecedented energy resolution and implications for deuterium-tritium fusion plasma diagnostics

    Science.gov (United States)

    Rigamonti, D.; Giacomelli, L.; Gorini, G.; Nocente, M.; Rebai, M.; Tardocchi, M.; Angelone, M.; Batistoni, P.; Cufar, A.; Ghani, Z.; Jednorog, S.; Klix, A.; Laszynska, E.; Loreti, S.; Pillon, M.; Popovichev, S.; Roberts, N.; Thomas, D.; Contributors, JET

    2018-04-01

    An accurate calibration of the JET neutron diagnostics with a 14 MeV neutron generator was performed in the first half of 2017 in order to provide a reliable measurement of the fusion power during the next JET deuterium-tritium (DT) campaign. In order to meet the target accuracy, the chosen neutron generator has been fully characterized at the Neutron Metrology Laboratory of the National Physical Laboratory (NPL), Teddington, United Kingdom. The present paper describes the measurements of the neutron energy spectra obtained using a high-resolution single-crystal diamond detector (SCD). The measurements, together with a new neutron source routine ‘ad hoc’ developed for the MCNP code, allowed the complex features of the neutron energy spectra resulting from the mixed D/T beam ions interacting with the T/D target nuclei to be resolved for the first time. From the spectral analysis a quantitative estimation of the beam ion composition has been made. The unprecedented intrinsic energy resolution (<1% full width at half maximum (FWHM) at 14 MeV) of diamond detectors opens up new prospects for diagnosing DT plasmas, such as, for instance, the possibility to study non-classical slowing down of the beam ions by neutron spectroscopy on ITER.

  8. Note on neutron scattering and the optical model near A = 208

    International Nuclear Information System (INIS)

    Guenther, P.; Havel, D.; Smith, A.

    1976-09-01

    Elastic neutron scattering cross sections of 206 Pb, 207 Pb, 208 Pb and 209 Bi are measured at incident neutron energy intervals of approx. 25 keV from 0.6 to 1.0 MeV with resolutions of approx. 25 keV. Optical model parameters are obtained from the energy-averaged experimental results for each of the isotopes. The observed elastic-neutron-scattering distributions and derived parameters for the lead isotopes (doubly magic or neutron holes in the closed shell) tend to differ from those of 209 Bi (doubly closed shell plus a proton). These potentials, derived in the approx. spherical region of A approximately 208, are extrapolated for the analysis of total and scattering cross sections of 238 U introducing only a small N-Z/A dependence and the known deformation of 238 U. Good descriptions of 238 U total cross sections are obtained from a few hundred keV to 10.0 MeV and the prediction of measured scattering distributions in the low MeV region are as suitable as frequently reported with other specially developed potentials

  9. Measurement of high energy neutrons via Lu(n,xn) reactions

    International Nuclear Information System (INIS)

    Henry, E.A.; Becker, J.A.; Archer, D.E.; Younes, W.; Stoyer, M.A.; Slaughter, D.

    1997-07-01

    High energy neutrons can be assayed by the use of the nuclear diagnostic material lutetium. We are measuring the (n,xn) cross sections for natural lutetium in order to develop it as a detector material. We are applying lutetium to diagnose the high energy neutrons produced in test target/blanket systems appropriate for the Accelerator Production of Tritium Project. 3 refs., 5 figs., 1 tab

  10. Improved fission neutron energy discrimination with {sup 4}He detectors through pulse filtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Ting, E-mail: ting.zhu@ufl.edu [University of Florida, Gainesville, FL (United States); Liang, Yinong; Rolison, Lucas; Barker, Cathleen; Lewis, Jason; Gokhale, Sasmit [University of Florida, Gainesville, FL (United States); Chandra, Rico [Arktis Radiation Detectors Ltd., Räffelstrasse 11, Zürich (Switzerland); Kiff, Scott [Sandia National Laboratories, CA (United States); Chung, Heejun [Korean Institute for Nuclear Nonproliferation and Control, 1534 Yuseong-daero, Yuseong-gu, Daejeon (Korea, Republic of); Ray, Heather; Baciak, James E.; Enqvist, Andreas; Jordan, Kelly A. [University of Florida, Gainesville, FL (United States)

    2017-03-11

    This paper presents experimental and computational techniques implemented for {sup 4}He gas scintillation detectors for induced fission neutron detection. Fission neutrons are produced when natural uranium samples are actively interrogated by 2.45 MeV deuterium-deuterium fusion reaction neutrons. Fission neutrons of energies greater than 2.45 MeV can be distinguished by their different scintillation pulse height spectra since {sup 4}He detectors retain incident fast neutron energy information. To enable the preferential detection of fast neutrons up to 10 MeV and suppress low-energy event counts, the detector photomultiplier gain is lowered and trigger threshold is increased. Pile-up and other unreliable events due to the interrogating neutron flux and background radiation are filtered out prior to the evaluation of pulse height spectra. With these problem-specific calibrations and data processing, the {sup 4}He detector's accuracy at discriminating fission neutrons up to 10 MeV is improved and verified with {sup 252}Cf spontaneous fission neutrons. Given the {sup 4}He detector's ability to differentiate fast neutron sources, this proof-of-concept active-interrogation measurement demonstrates the potential of special nuclear materials detection using a {sup 4}He fast neutron detection system.

  11. Low level neutron monitoring using high pressure 3He detectors

    International Nuclear Information System (INIS)

    Pszona, S.

    1995-01-01

    Three detectors, two spherical proportional counters and an ionisation chamber, all filled with 3 He to pressures of 160 kPa, 325 kPa and 1 MPa respectively have been experimentally studied with respect to their use for low level neutron monitoring. The ambient dose equivalent responses and the energy resolutions of these detectors have been determined. It is shown that spectral analysis of the signals from these detectors not only gives high sensitivity with regard to ambient dose equivalent but also improves the quality of the measurements. A special instrumentation for low level neutron monitoring is described in which a quality control method has been implemented. (Author)

  12. Utilization of low voltage D-T neutron generators in neutron physics studies

    International Nuclear Information System (INIS)

    Singkarat, S.

    1995-01-01

    In a small nuclear laboratory of a developing country a low voltage D-T neutron generator can be a very useful scientific apparatus. Such machines have been used successfully for more than 40 years in teaching and scientific research. The original continuous mode 150-kV D-T neutron generator has been modified to have also a capability of producing 2-ns pulsed neutrons. Together with a carefully designed 10 m long flight path collimator and shielding of a 25 cm diameter · 10 cm thick BC-501 neutron detector, the pulsing system was successfully used for measuring the double differential cross-section (DDX) of natural iron for 14.1-MeV neutron from the angle of 30 deg to 150 deg in 10 deg steps. In order to extend the utility of the generator, two methods for converting the almost monoenergetic 14-MeV neutrons to monoenergetic neutrons of lower energy were proposed and tested. Both designs used the neutron-proton interaction at a circular surface-of-revolution made of hydrocarbon materials. The first design is for a pulsed neutron generator and the second design is for an ordinary continuous mode generator. The latter method was successfully used to measure the scintillation light output of a 1.4 cm diameter spherical NE-213 scintillation detector. The neutron generator has also been used in the continuous search for improved neutron detection techniques. There is a proposal, based on Monte Carlo calculations, of using a scintillation fiber for a fast neutron spectrometer. Due to the slender shape of the fiber, the pattern of produced light gives a peak in the pulse height spectrum instead of the well-known rectangular-like distribution, when the fiber is bombarded end-on by a beam of 14-MeV neutrons. Experimental investigations were undertaken. Detailed investigations on the light transportation property of a short fiber were performed. The predicted peak has not yet been found but the fiber detector may be developed as a directional discrimination fast neutron

  13. Development of a Nuclear Reaction Database on Silicon for Simulation of Neutron-Induced Single-Event Upsets in Microelectronics and its Application

    International Nuclear Information System (INIS)

    Watanabe, Yukinobu; Kodama, Akihiro; Tukamoto, Yasuyuki; Nakashima, Hideki

    2005-01-01

    We have developed a cross-section database for neutron-induced reactions on 28Si in the energy range between 2 MeV and 3 GeV in order to analyze single-event upsets (SEUs) phenomena induced by cosmic-ray neutrons in microelectronic devices. A simplified spherical device model is proposed for simulation of the initial processes of SEUs. The model is applied to SEU cross-section calculations for semiconductor memory devices. The calculated results are compared with measured SEU cross sections and the other simulation result. The dependence of SEU cross sections on incident neutron energy and secondary ions having the most important effects on SEUs are discussed

  14. Thermal neutron diffusion parameters dependent on the flux energy distribution in finite hydrogenous media

    International Nuclear Information System (INIS)

    Drozdowicz, K.

    1999-01-01

    Macroscopic parameters for a description of the thermal neutron transport in finite volumes are considered. A very good correspondence between the theoretical and experimental parameters of hydrogenous media is attained. Thermal neutrons in the medium possess an energy distribution, which is dependent on the size (characterized by the geometric buckling) and on the neutron transport properties of the medium. In a hydrogenous material the thermal neutron transport is dominated by the scattering cross section which is strongly dependent on energy. A monoenergetic treatment of the thermal neutron group (admissible for other materials) leads in this case to a discrepancy between theoretical and experimental results. In the present paper the theoretical definitions of the pulsed thermal neutron parameters (the absorption rate, the diffusion coefficient, and the diffusion cooling coefficient) are based on Nelkin's analysis of the decay of a neutron pulse. Problems of the experimental determination of these parameters for a hydrogenous medium are discussed. A theoretical calculation of the pulsed parameters requires knowledge of the scattering kernel. For thermal neutrons it is individual for each hydrogenous material because neutron scattering on hydrogen nuclei bound in a molecule is affected by the molecular dynamics (characterized with internal energy modes which are comparable to the incident neutron energy). Granada's synthetic model for slow-neutron scattering is used. The complete up-dated formalism of calculation of the energy transfer scattering kernel after this model is presented in the paper. An influence of some minor variants within the model on the calculated differential and integral neutron parameters is shown. The theoretical energy-dependent scattering cross section (of Plexiglas) is compared to experimental results. A particular attention is paid to the calculation of the diffusion cooling coefficient. A solution of an equation, which determines the

  15. Oxygen enhancement ratio as a function of neutron energy with mammalian cells in culture

    International Nuclear Information System (INIS)

    Rini, F.J.; Hall, E.J.; Marino, S.A.

    1979-01-01

    Chinese hamster cells (V79) in culture under oxic and hypoxic conditions were irradiated with several neutron beams spanning a wide energy range to determine the oxygen enhancement ratio (OER). Eight essentially monoenergetic neutron beams, ranging from 0.22 to 13.6 MeV and a 0.11-MeV neutron spectrum, were produced at the Radiological Research Accelerator Facility (RARAF) at Brookhaven National Laboratory. Additional experiments were performed at the Naval Research Laboratory, Washington, DC, where neutrons are produced for radiotherapy by bombarding a beryllium target with 35-MeV deuterons. This beam has a broad energy spectrum with a mean energy of about 15 MeV. A maximum OER of about 1.9 was observed for 13.6-MeV neutrons. The OER values of the monoenergetic neutrons decreased with energy, plateaued at about 1.45 for the energy range from 0.22 to 2.0 MeV and increased slightly to about 1.55 for lower energy spectrum. In the light of microdosimetric data obtained for the neutron beams at RARAF, the OER appears to depend primarily on the intermediate-LET secondaries produced by neutrons in tissue, such as protons, while in contrast high LET-secondaries, such as α-particles and recoil ions, play a minor role. The studies using the NRL neutron beam resulted in a lower OER of about 1.67 as compared to the monoenergetic 13.6-MeV beam. This is a consequence of the fact that more of the dose is deposited by intermediate LET secondaries for the NRL neutron beam

  16. Photon strength in spherical and deformed heavy nuclei

    International Nuclear Information System (INIS)

    Grosse, E.; Junghans, A.; Birgersson, E.; Massarczyk, R.; Schramm, G.; Becvar, F.

    2010-01-01

    Information on the photon strength in heavy nuclei with mass A>150 will be given and compared to respective data. The photon strength function is a very important ingredient for statistical model calculations - especially when these are used to describe neutron capture. Several schemes for a transmutation of radioactive waste favor nuclear reactions with fast neutrons and these also influence the performance of various reactor types proposed to deliver nuclear energy together with only small quantities of such waste. Reactions with fast neutrons are far less studied as compared to those induced by thermal neutrons. As they are not easily accessible experimentally, reference is often made to calculations using the statistical model. Photon emission probabilities are needed as input to such calculations aiming for predictions on fission to capture ratios. From the favorable comparison of our parameterization to the experimental data for photon induced as well radiative capture processes in nuclei with various shapes and level densities we conclude what follows. First, the giant dipole resonance has very much the same properties in all heavy nuclei when their deformation is properly accounted for and its spreading width varies only smoothly with the resonance energies E k and not with the photon energy E γ . The radiative neutron capture results presented confirm strength data found in the literature. We also learn that our parameterization is at least a good approximation for photon energies below 4 MeV that dominate this process

  17. Irradiation tests of ITER candidate Hall sensors using two types of neutron spectra

    International Nuclear Information System (INIS)

    Duran, I.; Bolshakova, I.; Holyaka, R.; Viererbl, L.; Lahodova, Z.; Sentkerestiova, J.; Bem, P.

    2010-01-01

    We report on irradiation tests of InSb based Hall sensors at two irradiation facilities with two distinct types of neutron spectra. One was a fission reactor neutron spectrum with a significant presence of thermal neutrons, while another one was purely fast neutron field. Total neutron fluence of the order of 10 16 cm -2 was accumulated in both cases, leading to significant drop of Hall sensor sensitivity in case of fission reactor spectrum, while stable performance was observed at purely fast neutron spectrum. This finding suggests that performance of this particular type of Hall sensors is governed dominantly by transmutation. Additionally, it further stresses the need to test ITER candidate Hall sensors under neutron flux with ITER relevant spectrum.

  18. Analysis of a neutron scattering integral experiment on iron for neutron energies from 1 to 15 MeV

    International Nuclear Information System (INIS)

    Cramer, S.N.; Oblow, E.M.

    1976-11-01

    Monte Carlo calculations were made to analyze the results of an integral experiment with an iron sample to determine the adequacy of neutron scattering cross section data for iron. The experimental results analyzed included energy-dependent NE-213 detector count rates at a scattering angle of 90 deg and pulse-height spectra for scattered neutrons produced in an iron ring pulsed with a 1- to 20-MeV neutron source. The pulse-height data were unfolded to generate secondary neutron spectra at 90 deg as a function of incident neutron energy. Multigroup Monte Carlo calculations using the MORSE code and ENDF/B-IV cross sections were made to analyze all reported results. Discrepancies between calculated and measured responses were found for inelastic scattering reactions in the range from 1 to 4 MeV. These results were related to deficiencies in ENDF/B-IV iron cross section data

  19. Neutron quality parameters versus energy below 4 MeV from microdosimetric calculations

    International Nuclear Information System (INIS)

    Stinchcomb, T.G.; Borak, T.B.

    1983-01-01

    Charged-particle production by neutrons and the resulting energy-deposition spectra in micron-sized spheres of tissue of varying diameters were calculated from thermal energies to 4 MeV. These data were used to obtain dose-average values of several quality-indicating parameters as functions of neutron energy and of tissue sphere diameter. The contrast among the parameters is shown and discussed. Applications are made to two neutron spectra, one a fission spectrum in air and the other a moderated spectrum at the center of an irradiated cube of water

  20. Energy levels of GaAs/Al{sub x}Ga{sub 1-x}As/AlAs spherical quantum dot with an impurity

    Energy Technology Data Exchange (ETDEWEB)

    Boz, Figen Karaca, E-mail: figenb@trakya.edu.tr; Nisanci, Beyza; Aktas, Saban; Okan, S. Erol

    2016-11-30

    Highlights: • Energy levels and probability distribution of an electron in GaAs/AlxGa1-xAs/AlAs spherical quantum dot were calculated. • The size effects on the electronic binding energy were determined within a core/shell/shell model. • The differences between the impurity energies of the first and the second levels are detected. - Abstract: We have calculated the energy levels and the radial probability distributions of an electron with an impurity in a spherical quantum dot which is layered as GaAs/Al{sub x}Ga{sub 1-x}As/AlAs. The numerical method used is the fourth-order Runge–Kutta method in the framework of the effective mass approximation. The variation of the energy levels have been calculated as functions of the radius of the GaAs sphere and the thickness of Al{sub x}Ga{sub 1-x}As spherical layer considering effective mass and dielectric constant mismatches. The results have presented the importance of the geometry on the electronic properties of the spherical GaAs/Al{sub x}Ga{sub 1-x}As/AlAs quantum dot.

  1. Methodology of Continuous-Energy Adjoint Monte Carlo for Neutron, Photon, and Coupled Neutron-Photon Transport

    International Nuclear Information System (INIS)

    Hoogenboom, J. Eduard

    2003-01-01

    Adjoint Monte Carlo may be a useful alternative to regular Monte Carlo calculations in cases where a small detector inhibits an efficient Monte Carlo calculation as only very few particle histories will cross the detector. However, in general purpose Monte Carlo codes, normally only the multigroup form of adjoint Monte Carlo is implemented. In this article the general methodology for continuous-energy adjoint Monte Carlo neutron transport is reviewed and extended for photon and coupled neutron-photon transport. In the latter cases the discrete photons generated by annihilation or by neutron capture or inelastic scattering prevent a direct application of the general methodology. Two successive reaction events must be combined in the selection process to accommodate the adjoint analog of a reaction resulting in a photon with a discrete energy. Numerical examples illustrate the application of the theory for some simplified problems

  2. Research activities on dosimetry for high energy neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Yasuhiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    The external dosimetry research group of JAERI has been calculating dose conversion coefficients for high-energy radiations using particle transport simulation codes. The group has also been developing radiation dose measurement techniques for high-energy neutrons in collaboration with some university groups. (author)

  3. Some principal problems in physics and low-energy neutron physics

    International Nuclear Information System (INIS)

    Aleksandrov, Yu.A.

    2004-01-01

    The questions connected with internal particle (e.g. neutron) structure obtained at low-energy neutron physics are discussed. The first question deals with the charge neutron radius E 2 > 1/2 connected with the value of neutron-electron scattering length a ne determined at low neutron energies. At present, the obtained accuracy allows us to speak not only about the value of E 2 > but also on the segmentation of E 2 > into Dirac and Foldy addenda. The sign of the Dirac addendum is connected directly with the fundamental Yukawa theory explaining the origin of nuclear forces. One of the popular experimental values of the Dirac addendum (from a ne =(-1.32±0.03)·10 -16 cm) contradicts the Yukawa theory. The second question also concerns the subject of the structure of the neutron, namely its deformation. The notion of deformation (polarizability) of the nucleon in electromagnetic field was introduced in the mid-1950s. The reasons are given in favor of the opinion that the neutron polarizability was observed for the first time in neutron experiments as far back as 1957, i.e. earlier than proton polarizability was detected (1960). Finally, the third question deals with the search for a magnetic charge of the neutron. A beautiful experiment (Finkelstein, Shull, Zeilinger, 1986) testifying with high accuracy the absence of a magnetic charge of the neutron is discussed. This diffraction experiment was based on the concept of anomalously small effective mass of the neutron providing greatly enhanced sensitivity. The existence of an isolated magnetic charge in the nature would explain the quantization of electric and magnetic charges (Dirac, 1931)

  4. The neutron and low-energy gamma operational dosimetry in Melox plant

    International Nuclear Information System (INIS)

    Devita, A.D.

    2006-01-01

    M.E.L.O.X., subsidiary of A.R.E.V.A., produce M.O.X. fuels, a mixture of uranium and plutonium oxides. With the use in the process of plutonium oxide, there is a risk of external exposure to neutrons and low -energy gamma rays. By their characteristics, both these types of radiation are difficult to measure. The difficulty in measuring neutron doses lies in the fact that the fluence -to-dose equivalent conversion factor varies with the neutron energy level. In low -energy gamma (between 20 and 60 keV) dose measurement, the problem is detection using an electronic system. Just some years ago, very few industrial players were tempted to develop dosimeters in these areas in view of the poor demand and market prospects. Furthermore, radiation protection specialists needed a highly functional and robust direct reading dosimeters or, in other words, a device that was simple, reliable, inexpensive, small, and quick and easy to use in a wide range of working environments that could vary in terms of both the workstation and external exposure. In addition, at sites such as Melox, where company employees work alongside personnel from outside companies, the same types of dosimeters must be used so that dose -related data can be managed globally in one data base. Two technical solutions are available for neutron operational dosimetry - spectrometer-dosimeters and calibration dosimeters. Melox has opted for the use of calibration dosimeters. The reasons for this choice (technical, financial and organizational criteria) are given in this presentation. Before and during the various campaigns of M.O.X. fuels, the spectral characteristics relating to neutron fluence at different workstations and representative of personnel exposure levels were determined. A reference spectrometer was then used to determine the transfer function between fluence and dose in order to calibrate passive and operational dosimeters appropriately.The methodology to be set up should guarantee good

  5. An estimate of spherical impactor energy transfer for mechanical frequency up-conversion energy harvester

    Directory of Open Access Journals (Sweden)

    L. R. Corr

    2016-08-01

    Full Text Available Vibration energy harvesters, which use the impact mechanical frequency up-conversion technique, utilize an impactor, which gains kinetic energy from low frequency ambient environmental vibrations, to excite high frequency systems that efficiently convert mechanical energy to electrical energy. To take full advantage of the impact mechanical frequency up-conversion technique, it is prudent to understand the energy transfer from the low frequency excitations, to the impactor, and finally to the high frequency systems. In this work, the energy transfer from a spherical impactor to a multi degree of freedom spring / mass system, due to Hertzian impact, is investigated to gain insight on how best to design impact mechanical frequency up-conversion energy harvesters. Through this academic work, it is shown that the properties of the contact (or impact area, i.e., radius of curvature and material properties, only play a minor role in energy transfer and that the equivalent mass of the target system (i.e., the spring / mass system dictates the total amount of energy transferred during the impact. The novel approach of utilizing the well-known Hertzian impact methodology to gain an understanding of impact mechanical frequency up-conversion energy harvesters has made it clear that the impactor and the high frequency energy generating systems must be designed together as one system to ensure maximum energy transfer, leading to efficient ambient vibration energy harvesters.

  6. Possible dark energy imprints in the gravitational wave spectrum of mixed neutron-dark-energy stars

    Energy Technology Data Exchange (ETDEWEB)

    Yazadjiev, Stoytcho S. [Department of Theoretical Physics, Faculty of Physics, St. Kliment Ohridski University of Sofia, James Bourchier Blvd. 5, 1164 Sofia (Bulgaria); Doneva, Daniela D., E-mail: yazad@phys.uni-sofia.bg, E-mail: daniela.doneva@uni-tuebingen.de [Theoretical Astrophysics, IAAT, Eberhard-Karls University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen (Germany)

    2012-03-01

    In the present paper we study the oscillation spectrum of neutron stars containing both ordinary matter and dark energy in different proportions. Within the model we consider, the equilibrium configurations are numerically constructed and the results show that the properties of the mixed neuron-dark-energy star can differ significantly when the amount of dark energy in the stars is varied. The oscillations of the mixed neuron-dark-energy stars are studied in the Cowling approximation. As a result we find that the frequencies of the fundamental mode and the higher overtones are strongly affected by the dark energy content. This can be used in the future to detect the presence of dark energy in the neutron stars and to constrain the dark-energy models.

  7. Status of the low energy neutron source at Indiana University

    International Nuclear Information System (INIS)

    Baxter, D.V.; Cameron, J.M.; Derenchuk, V.P.; Lavelle, C.M.; Leuschner, M.B.; Lone, M.A.; Meyer, H.O.; Rinckel, T.; Snow, W.M.

    2005-01-01

    The National Science Foundation has recently approved funding for LENS (the low energy neutron source) at Indiana University and construction of this facility has begun. LENS represents a new paradigm for economically introducing neutron scattering into a university or industrial setting. In this design, neutrons are produced in a long-pulse (1 ms) mode through (p,n) reactions on a water-cooled Be target and the target is tightly coupled to a cryogenic moderator with a water reflector. This design gives a facility suitable for materials research, the development of new neutron instrumentation, and the education of new neutron scientists

  8. The single-collision thermalization approximation for application to cold neutron moderation problems

    International Nuclear Information System (INIS)

    Ritenour, R.L.

    1989-01-01

    The single collision thermalization (SCT) approximation models the thermalization process by assuming that neutrons attain a thermalized distribution with only a single collision within the moderating material, independent of the neutron's incident energy. The physical intuition on which this approximation is based is that the salient properties of neutron thermalization are accounted for in the first collision, and the effects of subsequent collisions tend to average out statistically. The independence of the neutron incident and outscattering energy leads to variable separability in the scattering kernel and, thus, significant simplification of the neutron thermalization problem. The approximation also addresses detailed balance and neutron conservation concerns. All of the tests performed on the SCT approximation yielded excellent results. The significance of the SCT approximation is that it greatly simplifies thermalization calculations for CNS design. Preliminary investigations with cases involving strong absorbers also indicates that this approximation may have broader applicability, as in the upgrading of the thermalization codes

  9. Pure Neutron Matter Constraints and Nuclear Symmetry Energy

    International Nuclear Information System (INIS)

    Fattoyev, F J; Newton, W G; Xu, Jun; Li, Bao-An

    2013-01-01

    In this review, we will discuss the results of our recent work [1] to study the general optimization of the pure isovector parameters of the popular relativistic mean-field (RMF) and Skyrme-Hartree-Fock (SHF) nuclear energy-density functionals (EDFs), using constraints on the pure neutron matter (PNM) equation of state (EoS) from recent ab initio calculations. By using RMF and SHF parameterizations that give equivalent predictions for ground-state properties of doubly magic nuclei and properties of symmetric nuclear matter (SNM) and PNM, we found that such optimization leads to broadly consistent symmetry energy J and its slope parameter L at saturation density within a tight range of α(J) sym , (b) the symmetry energy at supra-saturation densities, and (c) the radius of neutron stars.

  10. Investigation of the energy correlations of spallation neutrons by the MCNPX code

    International Nuclear Information System (INIS)

    Szieberth, Mate; Radocz, Gabor

    2011-01-01

    Earlier works have suggested that the energy correlations in a spallation source may influence the neutron noise measurements in an ADS. For the calculation of this effect not only the generally known and used one-particle spectrum is needed but also the so-called two particle spectrum, which describes also the energy correlations. Since measured data are not available for the energy distribution of the neutrons from a single spallation event the physical models of the MCNPX code have been used to investigate the effect. The calculational model has been successfully validated with measurements of the number distribution of spallation neutrons. The simulated one- and two-particle energy distributions and spectra proved that the energy correlations exist and have an important effect in low multiplicity spallation events and in thin targets. On the other hand for thick targets this effect appears negligible and the factorization of the two-particle spectrum seems an acceptable approximation. Further investigations are in hand to quantify the actual effect of the energy correlations on the neutron noise measurements. (author)

  11. Utilization of low voltage D-T neutron generators in neutron physics studies

    Energy Technology Data Exchange (ETDEWEB)

    Singkarat, S.

    1995-08-01

    In a small nuclear laboratory of a developing country a low voltage D-T neutron generator can be a very useful scientific apparatus. Such machines have been used successfully for more than 40 years in teaching and scientific research. The original continuous mode 150-kV D-T neutron generator has been modified to have also a capability of producing 2-ns pulsed neutrons. Together with a carefully designed 10 m long flight path collimator and shielding of a 25 cm diameter {center_dot} 10 cm thick BC-501 neutron detector, the pulsing system was successfully used for measuring the double differential cross-section (DDX) of natural iron for 14.1-MeV neutron from the angle of 30 deg to 150 deg in 10 deg steps. In order to extend the utility of the generator, two methods for converting the almost monoenergetic 14-MeV neutrons to monoenergetic neutrons of lower energy were proposed and tested. The first method uses a pulsed neutron generator and the second method uses an ordinary continuous mode generator. The latter method was successfully used to measure the scintillation light output of a 1.4 cm diameter spherical NE-213 scintillation detector. The neutron generator has also been used in the continuous search for improved neutron detection techniques. There is a proposal, based on Monte Carlo calculations, of using a scintillation fiber for a fast neutron spectrometer. Due to the slender shape of the fiber, the pattern of produced light gives a peak in the pulse height spectrum instead of the well-known rectangular-like distribution, when the fiber is bombarded end-on by a beam of 14-MeV neutrons. Experimental investigations were undertaken. Detailed investigations on the light transportation property of a short fiber were performed. The predicted peak has not yet been found but the fiber detector may be developed as a directional discrimination fast neutron detector. 18 refs.

  12. Assessment of the TASS 1-D neutronics model for the westinghouse and ABB-CE type PWR reactivity induced transients

    International Nuclear Information System (INIS)

    Choi, J.D.; Yoon, H.Y.; Um, K.S.; Kim, H.C.; Sim, S.K.

    1997-01-01

    Best estimate transient analysis code, TASS, has been developed for the normal and transient simulation of the Westinghouse and ABB-CE type PWRs. TASS thermal hydraulic model is based on the non-homogeneous, non-equilibrium two-phase continuity, energy and mixture momentum equations with constitutive relations for closure. Core neutronics model employs both the point kinetics and one-dimensional neutron diffusion model. Semi-implicit numerical scheme is used to solve the discretized finite difference equations. TASS one dimensional neutronics core model has been assessed through the reactivity induced transient analyses for the KORI-3, three loop Westinghouse PWR, and Younggwang-3 (YGN-3), two-loop ABB-CE PWR, nuclear power plants currently operating in Korea. The assessment showed that the TASS one dimensional neutronics core model can be applied for the Westinghouse and ABB-CE type PWRs to gain thermal margin which is necessary for a potential use of the high fuel burnup, extended fuel cycle, power upgrading and for the plant life extension

  13. Conception of a New Recoil Proton Telescope for Real-Time Neutron Spectrometry in Proton-Therapy

    Science.gov (United States)

    Combe, Rodolphe; Arbor, Nicolas; el Bitar, Ziad; Higueret, Stéphane; Husson, Daniel

    2018-01-01

    Neutrons are the main type of secondary particles emitted in proton-therapy. Because of the risk of secondary cancer and other late occurring effects, the neutron dose should be included in the out-of-field dose calculations. A neutron spectrometer has to be used to take into account the energy dependence of the neutron radiological weighting factor. Due to its high dependence on various parameters of the irradiation (beam, accelerator, patient), the neutron spectrum should be measured independently for each treatment. The current reference method for the measurement of the neutron energy, the Bonner Sphere System, consists of several homogeneous polyethylene spheres with increasing diameters equipped with a proportional counter. It provides a highresolution reconstruction of the neutron spectrum but requires a time-consuming work of signal deconvolution. New neutron spectrometers are being developed, but the main experimental limitation remains the high neutron flux in proton therapy treatment rooms. A new model of a real-time neutron spectrometer, based on a Recoil Proton Telescope technology, has been developed at the IPHC. It enables a real-time high-rate reconstruction of the neutron spectrum from the measurement of the recoil proton trajectory and energy. A new fast-readout microelectronic integrated sensor, called FastPixN, has been developed for this specific purpose. A first prototype, able to detect neutrons between 5 and 20 MeV, has already been validated for metrology with the AMANDE facility at Cadarache. The geometry of the new Recoil Proton Telescope has been optimized via extensive Geant4 Monte Carlo simulations. Uncertainty sources have been carefully studied in order to improve simultaneously efficiency and energy resolution, and solutions have been found to suppress the various expected backgrounds. We are currently upgrading the prototype for secondary neutron detection in proton therapy applications.

  14. ENERGY RESPONSE OF FLUORESCENT NUCLEAR TRACK DETECTORS OF VARIOUS COLORATIONS TO MONOENERGETIC NEUTRONS.

    Science.gov (United States)

    Fomenko, V; Moreno, B; Million, M; Harrison, J; Akselrod, M

    2017-10-25

    The neutron-energy dependence of the track-counting sensitivity of fluorescent nuclear track detectors (FNTDs) at two ranges of Mg doping, resulting in different crystal colorations, was investigated. The performance of FNTDs was studied with the following converters: Li-glass for thermal to intermediate-energy neutrons, polyethylene for fast neutrons, and polytetrafluoroethylene (Teflon™) for photon- and radon-background subtraction. The irradiations with monoenergetic neutrons were performed at the National Physics Laboratory (NPL), UK. The energy range was varied from 144 keV to 16.5 MeV in the personal dose equivalent range from 1 to 3 mSv. Monte Carlo simulations were performed to model the response of FNTDs to monoenergetic neutrons. A good agreement with the experimental data was observed suggesting the development of a basic model for future MC studies. Further work will focus on increasing FNTD sensitivity to low-energy neutrons and developing a faster imaging technique for scanning larger areas to improve counting statistics. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  15. Neutron scattering from elemental indium, the optical model, and the bound-state potential

    Energy Technology Data Exchange (ETDEWEB)

    Chiba, S. (Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan)); Guenther, P.T.; Lawson, R.D.; Smith, A.B. (Argonne National Lab., IL (USA))

    1990-06-01

    Neutron differential elastic-scattering cross sections of elemental indium are measured from 4.5 to 10 MeV at incident-energy intervals of {approx}500 keV. Seventy or more differential values are obtained at each incident energy, distributed between {approx}18{degree} and 160{degree}. These experimental results are combined with lower-energy values previously obtained at this laboratory, and with 11 and 14 MeV results in the literature, to form a comprehensive elastic-scattering database extending from {approx}1.5 to 14 MeV. These data are interpreted in terms of a conventional spherical optical model. The resulting potential is extrapolated to the bound-state regime. It is shown that in the middle of the 50--82 neutron shell, the potential derived from the scattering results adequately describes the binding energies of article states, but does not do well for hole states. The latter shortcoming is attributed to the holes states having occupational probabilities sufficiently different from unity, so that the exclusion principle become a factor, and to the rearrangement of the neutron core. 68 refs.

  16. Neutron scattering from elemental indium, the optical model, and the bound-state potential

    International Nuclear Information System (INIS)

    Chiba, S.; Guenther, P.T.; Lawson, R.D.; Smith, A.B.

    1990-01-01

    Neutron differential elastic-scattering cross sections of elemental indium are measured from 4.5 to 10 MeV at incident-energy intervals of ∼500 keV. Seventy or more differential values are obtained at each incident energy, distributed between ∼18 degree and 160 degree. These experimental results are combined with lower-energy values previously obtained at this laboratory, and with 11 and 14 MeV results in the literature, to form a comprehensive elastic-scattering database extending from ∼1.5 to 14 MeV. These data are interpreted in terms of a conventional spherical optical model. The resulting potential is extrapolated to the bound-state regime. It is shown that in the middle of the 50--82 neutron shell, the potential derived from the scattering results adequately describes the binding energies of article states, but does not do well for hole states. The latter shortcoming is attributed to the holes states having occupational probabilities sufficiently different from unity, so that the exclusion principle become a factor, and to the rearrangement of the neutron core. 68 refs

  17. The development of BH3105E type neutron dose-equivalent meter

    International Nuclear Information System (INIS)

    Ji Changsong; Wang Tingting; Zhang Shuheng; Tan Baozeng

    2011-01-01

    A new BH3105E Type Neutron Dose-equivalent Meter has been developed. The 'multi-stick' ab- sorption method is used for thermal -14 MeV neutron equal dose-equivalent detection, what gives a high neutron sensitivity of 5 cps/μSv · h-1. RS-232 interface is accepted for signal communication (authors)

  18. The neutron dose equivalent around high energy medical electron linear accelerators

    Directory of Open Access Journals (Sweden)

    Poje Marina

    2014-01-01

    Full Text Available The measurement of neutron dose equivalent was made in four dual energy linear accelerator rooms. Two of the rooms were reconstructed after decommissioning of 60Co units, so the main limitation was the space. The measurements were performed by a nuclear track etched detectors LR-115 associated with the converter (radiator that consist of 10B and with the active neutron detector Thermo BIOREM FHT 742. The detectors were set at several locations to evaluate the neutron ambient dose equivalent and/or neutron dose rate to which medical personnel could be exposed. Also, the neutron dose dependence on collimator aperture was analyzed. The obtained neutron dose rates outside the accelerator rooms were several times smaller than the neutron dose rates inside the accelerator rooms. Nevertheless, the measured neutron dose equivalent was not negligible from the aspect of the personal dosimetry with almost 2 mSv a year per person in the areas occupied by staff (conservative estimation. In rooms with 15 MV accelerators, the neutron exposure to the personnel was significantly lower than in the rooms having 18 MV accelerators installed. It was even more pronounced in the room reconstructed after the 60Co decommissioning. This study confirms that shielding from the neutron radiation should be considered when building vaults for high energy linear accelerators, especially when the space constraints exist.

  19. Improving the neutron-to-photon discrimination capability of detectors used for neutron dosimetry in high energy photon beam radiotherapy

    International Nuclear Information System (INIS)

    Irazola, L.; Terrón, J.A.; Bedogni, R; Pola, A.; Lorenzoli, M.; Sánchez-Nieto, B.; Gómez, F.; Sánchez-Doblado, F.

    2016-01-01

    The increasing interest of the medical community to radioinduced second malignancies due to photoneutrons in patients undergoing high-energy radiotherapy, has stimulated in recent years the study of peripheral doses, including the development of some dedicated active detectors. Although these devices are designed to respond to neutrons only, their parasitic photon response is usually not identically zero and anisotropic. The impact of these facts on measurement accuracy can be important, especially in points close to the photon field-edge. A simple method to estimate the photon contribution to detector readings is to cover it with a thermal neutron absorber with reduced secondary photon emission, such as a borated rubber. This technique was applied to the TNRD (Thermal Neutron Rate Detector), recently validated for thermal neutron measurements in high-energy photon radiotherapy. The positive results, together with the accessibility of the method, encourage its application to other detectors and different clinical scenarios. - Highlights: • Neutron-to-photon discrimination of a thermal neutron detector used in radiotherapy. • Photon and anisotropic response study with distance and beam incidence of thermal neutron detector. • Borated rubber for estimating photon contribution in any thermal neutron detector.

  20. Supplying safety and energy independence

    International Nuclear Information System (INIS)

    Maillard, D.

    2001-03-01

    The french Observatory of the Energy wonders about the energy independence notion. Many risks are possible: physical, economical, geo-political, social and ecological risks. Because those risks are numerous, the answers for a supplying safety are also numerous. In this context the energy policy is a difficult art which the public opinion needs to be more and more aware. (A.L.B.)

  1. Bounds on the mass and the moment of inertia of nonrotating neutron stars

    International Nuclear Information System (INIS)

    Sabbadini, A.G.

    1976-01-01

    Bounds are placed on the mass and the moment of inertia of relativistic, spherical, perfect fluid neutron stars, under minimal assumptions on the equation of state of neutron star matter above nuclear densities. The assumptions are: the pressure p, the density rho, and the derivative dp/d rho are positive. The equation of state is assumed to be known below the density rho 0 = 5 x 10 14 g/cm 3 . The upper bound on the mass of a nonrotating neutron star, under these assumptions, is found to be 5 M/sub solar mass/. Upper and lower bounds on the moment of inertia are derived: for a spherical star of given mass and radius (without assuming a specific equation of state in any density region); for a spherical neutron star of arbitrary mass and radius; for a spherical neutron star of given mass. These bounds are optimum ones, in the sense that there always exists a configuration consistent with the assumptions, having a moment of inertia equal to the bound. Using these results for the moment of inertia, the correction to the upper bound on the mass due to slow rotation is discussed

  2. Results of the systematic study of neutron dosimeters and neutron radiometers responses from Bruyeres and Valduc's experiments

    International Nuclear Information System (INIS)

    Pras, Ph.; Ledoux, X.; Patin, Y.

    1999-01-01

    This document gives the results of the systematic study of neutron dosimeters (Bubbles detectors) and neutron radiometers (Cramal, Nausicaa, EGG Lb6411) with standard sources and with the Bruyeres Van de Graaff 4MV accelerator. The dose equivalent rate response as a function of the neutron energy is parameterized. Even for low dose equivalent rate, a good reproducibility of the measurements is found in the strict respect of a given method. The response of the different systems is independent of the dose equivalent rate. (author)

  3. Measurement of prompt neutron spectra from the "2"3"9Pu(n, f ) fission reaction for incident neutron energies from 1 to 200 MeV

    International Nuclear Information System (INIS)

    Chatillon, A.; Belier, G.; Granier, T.; Laurent, B.; Morillon, B.; Taieb, J.; Haight, R.C.; Devlin, M.; Nelson, R.O.; Noda, R.S.; O'Donnell, J.M.

    2014-01-01

    Prompt fission neutron spectra in the neutron-induced fission of "2"3"9Pu have been measured for incident neutron energies from 1 to 200 MeV at the Los Alamos Neutron Science Center. Mean energies deduced from the prompt fission neutron spectra (PFNS) lead to the observation of the opening of the second chance fission at 7 MeV and to indications for the openings of fission channels of third and fourth chances. Moreover, the general trend of the measured PFNS is well reproduced by the different models. The comparison between data and models presents, however, two discrepancies. First, the prompt neutron mean energy seems constant for neutron energy, at least up to 7 MeV, whereas in the theoretical calculations it is continuously increasing. Second, data disagree with models on the shape of the high energy part of the PFNS, where our data suggest a softer spectrum than the predictions. (authors)

  4. Supersoft Symmetry Energy Encountering Non-Newtonian Gravity in Neutron Stars

    International Nuclear Information System (INIS)

    Wen Dehua; Li Baoan; Chen Liewen

    2009-01-01

    Considering the non-Newtonian gravity proposed in grand unification theories, we show that the stability and observed global properties of neutron stars cannot rule out the supersoft nuclear symmetry energies at suprasaturation densities. The degree of possible violation of the inverse-square law of gravity in neutron stars is estimated using an equation of state of neutron-rich nuclear matter consistent with the available terrestrial laboratory data.

  5. Development of a TPC for energy and fluence references in low energies neutronic fields (from 8 keV to 5 MeV)

    International Nuclear Information System (INIS)

    Maire, Donovan

    2015-01-01

    In order to judge the measurement reliability, metrology requires to measure quantities with their uncertainties, in relation to a reference through a documented and unbroken chain of calibrations. In neutron radiation field, instrument response has to be known as a function of the neutron energy. Then detector calibrations are required using reference neutron fields. In France, primary reference neutron fields are held by the LNE-IRSN, at the Laboratory for Neutron Metrology and Dosimetry (LMDN). In order to improve reference neutron field characterization, the LNE-IRSN MIMAC μTPC has been developed. This detector is a Time Projection Chamber (TPC), using a gas at low pressure (30 mbar abs. to 1 bar abs.). Nuclear recoils are generated by neutron elastic scattering onto gas atoms. By measuring the nuclear recoil energy and scattering angle, the μTPC detector is able to measure the energy distribution of the neutron fluence between 8 keV and 5 MeV. The main challenge was to perform accurate spectrometry of neutron fields in the keV range, following a primary procedure. First of all, a metrological approach was followed in order to master every physical process taking part in the neutron detection. This approach led to develop the direct and inverse models, representing the detector response function and its inverse function respectively. Using this detailed characterization, the energy distribution of the neutron fluence has been measured for a continuous neutron field of 27 keV. The reconstructed energy is 28,2 ± 4,5 keV, the difference between μTPC integral fluence measurement and other measurement methods is less than 6%. The LNE-IRSN MIMAC μTPC system becomes the only one system able to measure simultaneously energy and fluence at energies lower than 100 keV, following a primary procedure. The project goal is then reached. These measurements at energies lower than 100 keV shows also a non-linearity between the ionization charge and the ion kinetic energy

  6. Accuracy estimation for intermediate and low energy neutron transport calculation with Monte Carlo code MCNP

    International Nuclear Information System (INIS)

    Kotegawa, Hiroshi; Sasamoto, Nobuo; Tanaka, Shun-ichi

    1987-02-01

    Both ''measured radioactive inventory due to neutron activation in the shield concrete of JPDR'' and ''measured intermediate and low energy neutron spectra penetrating through a graphite sphere'' are analyzed using a continuous energy model Monte Carlo code MCNP so as to estimate calculational accuracy of the code for neutron transport in thermal and epithermal energy regions. Analyses reveal that MCNP calculates thermal neutron spectra fairly accurately, while it apparently over-estimates epithermal neutron spectra (of approximate 1/E distribution) as compared with the measurements. (author)

  7. Designing a new type of neutron detector for neutron and gamma-ray discrimination via GEANT4

    International Nuclear Information System (INIS)

    Shan, Qing; Chu, Shengnan; Ling, Yongsheng; Cai, Pingkun; Jia, Wenbao

    2016-01-01

    Design of a new type of neutron detector, consisting of a fast neutron converter, plastic scintillator, and Cherenkov detector, to discriminate 14-MeV fast neutrons and gamma rays in a pulsed n–γ mixed field and monitor their neutron fluxes is reported in this study. Both neutrons and gamma rays can produce fluorescence in the scintillator when they are incident on the detector. However, only the secondary charged particles of the gamma rays can produce Cherenkov light in the Cherenkov detector. The neutron and gamma-ray fluxes can be calculated by measuring the fluorescence and Cherenkov light. The GEANT4 Monte Carlo simulation toolkit is used to simulate the whole process occurring in the detector, whose optimum parameters are known. Analysis of the simulation results leads to a calculation method of neutron flux. This method is verified by calculating the neutron fluxes using pulsed n–γ mixed fields with different n/γ ratios, and the results show that the relative errors of all calculations are <5%. - Highlights: • A neutron detector is developed to discriminate 14-MeV fast neutrons and gamma rays. • The GEANT4 is used to optimize the parameters of the detector. • A calculation method of neutron flux is established through the simulation. • Several n/γ mixture fields are simulated to validate of the calculation method.

  8. 6LiF sandwich type detectors for low dose individual monitoring in mixed neutron-photon fields

    International Nuclear Information System (INIS)

    Olko, P.; Budzanowski, M.; Bilski, P.; Burgkhardt, B.; Piesch, E.

    1994-01-01

    ICRP Publication 60 recommends the reduction of the annual dose limit for occupational exposure from 50 to 20 mSv and a doubling of the quality factor for medium energy neutrons. If occupational doses are evaluated every month (which is obligatory e.g. in Germany and in Poland), the individual neutron dosemeter will have to measure neutron doses in the range of 100 μSv. No commercially available, automatic individual dosimetry monitoring system exists that fulfils this requirement. Some of the parameters which influence the evaluation of the neutron dose from readings of TL dosemeters have been studied in order to decrease the variance of the measured neutron signal. In mixed neutron-photon fields, clear separation of the neutron component from the total reading depends also on the uncertainty of the gamma dose measurements. While the thermal albedo neutrons are absorbed mostly at the surface of the 6 LiF detector, the reduction of the detector thickness results in a decrease of its photon sensitivity, while its neutron sensitivity is almost principally maintained. As a consequence, the uncertainty of gamma dose contributes with lower weight to the variance of the evaluated neutron signal. First tests of an optimised 200 μm thick sandwich detector and 0.9 mm thick standard LiF chips were made at low neutron and photon dose ranges using different readers, in order to determine the uncertainty versus dose for different neutron-photon combinations. The conditions under which the new sandwich type detectors may improve albedo neutron dosimetry are demonstrated. (Author)

  9. Thermo-mechanical screening tests to qualify beryllium pebble beds with non-spherical pebbles

    Energy Technology Data Exchange (ETDEWEB)

    Reimann, Joerg, E-mail: joerg.reimann@partner.kit.edu [IKET, Karlsruhe Institute of Technology, Karlsruhe (Germany); Fretz, Benjamin [KBHF GmbH, Eggenstein-Leopoldshafen (Germany); Pupeschi, Simone [IAM, Karlsruhe Institute of Technology, Karlsruhe (Germany)

    2015-10-15

    Highlights: • In present ceramic breeder blankets, pebble-shaped beryllium is used as a neutron multiplier. • Spherical pebbles are considered as the candidate material, however, non-spherical particles are of economic interest. • Thermo-mechanical pebble bed data do merely exist for non-spherical beryllium grades. • Uniaxial compression tests (UCTs), combined with the Hot Wire Technique (HWT) were used to measure the stress–strain relations and the thermal conductivity. • A small experimental set-up had to be used and a detailed 3D modelling was of prime importance. • Compared to spherical pebble beds, non-spherical pebble beds are generally softer and mainly the thermal conductivity is lower. - Abstract: In present ceramic breeder blankets, pebble-shaped beryllium is used as a neutron multiplier. Fairly spherical pebbles are considered as a candidate material, however, non-spherical particles are of economic interest because production costs are much lower. Yet, thermo-mechanical pebble bed data do merely exist for these beryllium grades, and the blanket relevant potential of these grades cannot be judged. Screening experiments were performed with three different grades of non-spherical beryllium pebbles, produced by different companies, accompanied by experiments with the reference beryllium pebble beds. Uniaxial compression tests (UCTs), combined with the Hot Wire Technique (HWT), were performed to measure both the stress–strain relation and the thermal conductivity, k, at different stress levels. Because of the limited amounts of the non-spherical materials, the experimental set-ups were small and a detailed 3D modelling was of prime importance in order to prove that the used design was appropriate. Compared to the pebble beds consisting of spherical pebbles, non-spherical pebble beds are generally softer (smaller stress for a given strain), and, mainly as a consequence of this, for a given strain value, the thermal conductivity is lower. This

  10. The extended range neutron rem counter LINUS: overview and latest developments

    International Nuclear Information System (INIS)

    Birattari, C.; Rancati, T.; Esposito, A.; Pelliccioni, M.; Ferrari, A.; Silari, M.

    1997-01-01

    The 'history' of the extended range neutron rem counter LINUS, since its first conception in 1990 is reviewed, along with the latest developments. These include the calibration of the initially cylindrical version with nearly monoenergetic neutrons in the energy range 34-66 MeV, a detailed evaluation of the anisotropy of its response function, the construction and calibration of an improved spherical version, and recent measurements in reference high energy stray radiation fields. The instrument can now be considered as being fully characterized. Similar monitors built by other laboratories following the present design have confirmed its performances. The instrument is now in semi-routine use at a number of particle accelerator facilities and is one of several devices used on-board of aircrafts for assessing the exposure to cosmic rays at commercial flight altitudes. (author)

  11. Application of neutron radiography in Japan

    International Nuclear Information System (INIS)

    Kobayashi, M.; Wada, N.; Sekita, J.; Sanno-cho, Ota-ku, Tokyo, Japan)

    1983-01-01

    The history and the present state of neutron radiography in Japan are reviewed. Three types of neutron sources, namely nuclear reactors, accelerators and radioisotopes are now used. The interests on the application on neutron radiography become greater and greater in the industries, such as atomic energy, aeronautics and space etc. (Auth.)

  12. Development of slow neutron dose meter by track counting

    International Nuclear Information System (INIS)

    Nozaki, Tetsuya; Takeuchi, Hiroshi; Hasnel, S.; Honda, Teruyuki; Harasawa, Susumu.

    1993-01-01

    Prototypes of a plate type and two types of semispherical dosemeter were manufactured and their performances were tested. Polyallyl diglycol carbonate (PADC) was employed as neutron detector and covered with natural LiF and 6 Li-enriched LiF ceramics. They were irradiated in the TRIGA II Reactor of the Rikkyo University, and the sensitivity characteristics for incident angles and neutron energies were analyzed. It is concluded that it may be possible to manufacture small sized neutron dosemeter of flat response to wide energy range from thermal neutrons to epithermal neutrons with sufficient sensitivity for personal monitoring, using LiF ceramic as neutron filters and neutron converters. However the following issues are to be solved: the optimization of thickness of the LiF filter, the effects of albedo of the human body, and the applicability to the intermediate neutrons. (A.Y.)

  13. Neutron energy spectrum influence on irradiation hardening and microstructural development of tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Makoto, E-mail: makoto.fukuda@qse.tohoku.ac.jp [Tohoku University, Sendai, 980-8579 (Japan); Kiran Kumar, N.A.P.; Koyanagi, Takaaki; Garrison, Lauren M. [Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Snead, Lance L. [Massachusetts Institute of Technology, Cambridge, MA, 02139 (United States); Katoh, Yutai [Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Hasegawa, Akira [Tohoku University, Sendai, 980-8579 (Japan)

    2016-10-15

    Neutron irradiation to single crystal pure tungsten was performed in the mixed spectrum High Flux Isotope Reactor (HFIR). To investigate the influences of neutron energy spectrum, the microstructure and irradiation hardening were compared with previous data obtained from the irradiation campaigns in the mixed spectrum Japan Material Testing Reactor (JMTR) and the sodium-cooled fast reactor Joyo. The irradiation temperatures were in the range of ∼90–∼800 °C and fast neutron fluences were 0.02–9.00 × 10{sup 25} n/m{sup 2} (E > 0.1 MeV). Post irradiation evaluation included Vickers hardness measurements and transmission electron microscopy. The hardness and microstructure changes exhibited a clear dependence on the neutron energy spectrum. The hardness appeared to increase with increasing thermal neutron flux when fast fluence exceeds 1 × 10{sup 25} n/m{sup 2} (E > 0.1 MeV). Irradiation induced precipitates considered to be χ- and σ-phases were observed in samples irradiated to >1 × 10{sup 25} n/m{sup 2} (E > 0.1 MeV), which were pronounced at high dose and due to the very high thermal neutron flux of HFIR. Although the irradiation hardening mainly caused by defects clusters in a low dose regime, the transmutation-induced precipitation appeared to impose additional significant hardening of the tungsten. - Highlights: • The microstructure and irradiation hardening of single crystal pure W irradiated in HFIR was investigated. • The neutron energy spectrum influence was evaluated by comparing the HFIR results with previous work in Joyo and JMTR. • In the dose range up to ∼1 dpa, the neutron energy spectrum influence of irradiation hardening was not clear. • In the dose range above 1 dpa, the neutron energy influence on irradiation hardening and microstructural development was clearly observed. • The irradiation induced precipitates caused significant irradiation hardening of pure W irradiated in HFIR.

  14. Use of code DTF-4 for determining the coefficient of back-reflection of the neutron within the thermonuclear plasma of a thermonuclear reactor controlled by the rate of the fission reactions. Pt. 1

    International Nuclear Information System (INIS)

    Cristea, G.

    1975-01-01

    The neutron problems are discussed of the thermonuclear reactor controlled by the rate of the fission reactions. The results obtained by rolling the DTF-4 program in a spherical geometry in the case of an ''external source'' problem permit to draw conclusions concerning the problems of the neutronics system of this thermonuclear reactor type. A relation is deduced for estimating the coefficient of back-reflection of the neutrons within the thermonuclear plasma and the focussion system is discussed of the neutronics of this reactor type

  15. Response of spherical gravitational wave antenna modes to high-energy cosmic ray particles

    International Nuclear Information System (INIS)

    Jr, R M Marinho; Magalhaes, N S; Aguiar, O D; Frajuca, C

    2002-01-01

    High-energy cosmic ray particles are expected to be a significant source of noise in resonant mass gravitational wave detectors close to the quantum limit. The spherical, fourth generation antennas have been designed to attain such a limit. In this work we will show how the energy of a cosmic ray particle interacting with such an antenna is distributed over its eigenmodes. We will then make some comments on the relevant consequences of such a distribution for gravitational wave detection

  16. Response of spherical gravitational wave antenna modes to high-energy cosmic ray particles

    CERN Document Server

    Marinho, R M; Aguiar, O D; Frajuca, C

    2002-01-01

    High-energy cosmic ray particles are expected to be a significant source of noise in resonant mass gravitational wave detectors close to the quantum limit. The spherical, fourth generation antennas have been designed to attain such a limit. In this work we will show how the energy of a cosmic ray particle interacting with such an antenna is distributed over its eigenmodes. We will then make some comments on the relevant consequences of such a distribution for gravitational wave detection.

  17. The total kinetic energy release in the fast neutron-induced fission of {sup 232}Th

    Energy Technology Data Exchange (ETDEWEB)

    King, Jonathan; Yanez, Ricardo; Loveland, Walter; Barrett, J. Spencer; Oscar, Breland [Oregon State University, Dept. of Chemistry, Corvallis, OR (United States); Fotiades, Nikolaos; Tovesson, Fredrik; Young Lee, Hye [Los Alamos National Laboratory, Physics Division, Los Alamos, NM (United States)

    2017-12-15

    The post-emission total kinetic energy release (TKE) in the neutron-induced fission of {sup 232}Th was measured (using white spectrum neutrons from LANSCE) for neutron energies from E{sub n} = 3 to 91 MeV. In this energy range the average post-neutron total kinetic energy release decreases from 162.3 ± 0.3 at E{sub n} = 3 MeV to 154.9 ± 0.3 MeV at E{sub n} = 91 MeV. Analysis of the fission mass distributions indicates that the decrease in TKE with increasing neutron energy is a combination of increasing yields of symmetric fission (which has a lower associated TKE) and a decrease in the TKE release in asymmetric fission. (orig.)

  18. Measurements of time dependent energy spectra of neutrons in a small graphite assembly

    International Nuclear Information System (INIS)

    Fujita, Yoshiaki; Sakamoto, Shigeyasu; Aizawa, Otohiko; Takahashi, Akito; Sumita, Kenji.

    1975-01-01

    The time-dependent energy spectra of neutrons have been measured in a small 30x30x30 cm 3 graphite assembly by means of the linac-chopper method, with a view to establishing experimental evidence that there is no asymptotic spectrum in such a small assembly, and in order to study the non-asymptotic behavior of neutrons. The arrangement of a polyethylene pre-moderator adjacent to the assembly made the measurements possible with the improvement obtained thereby of the neutron counting statistics. It was indicated from calculation that the presence of the pre-moderator had little effect - at least above the Bragg cut-off energy - on the evolution in time of the energy spectra of neutrons in the graphite assembly. The experimental results indicated very probable disappearance of asymptotic spectra, and revealed significant enhancement of trapping at Bragg energies with the lapse of time. This is consistent with the results of pulsed neutron experiments in small assemblies conducted by Takahashi et al., and falls in line with de Saussure's approximation. The spectra in the graphite assembly showed significant space dependence, the spectra becoming harder with increasing distance from the pre-moderator. This hardening may be attributed to the relatively faster propagation of higher energy neutrons. (auth.)

  19. PANDORA, a large volume low-energy neutron detector with real-time neutron-gamma discrimination

    Science.gov (United States)

    Stuhl, L.; Sasano, M.; Yako, K.; Yasuda, J.; Baba, H.; Ota, S.; Uesaka, T.

    2017-09-01

    The PANDORA (Particle Analyzer Neutron Detector Of Real-time Acquisition) system, which was developed for use in inverse kinematics experiments with unstable isotope beams, is a neutron detector based on a plastic scintillator coupled to a digital readout. PANDORA can be used for any reaction study involving the emission of low energy neutrons (100 keV-10 MeV) where background suppression and an increased signal-to-noise ratio are crucial. The digital readout system provides an opportunity for pulse shape discrimination (PSD) of the detected particles as well as intelligent triggering based on PSD. The figure of merit results of PANDORA are compared to the data in literature. Using PANDORA, 91 ± 1% of all detected neutrons can be separated, while 91 ± 1% of the detected gamma rays can be excluded, reducing the gamma ray background by one order of magnitude.

  20. Neutron dose and energy spectra measurements at Savannah River Plant

    International Nuclear Information System (INIS)

    Brackenbush, L.W.; Soldat, K.L.; Haggard, D.L.; Faust, L.G.; Tomeraasen, P.L.

    1987-08-01

    Because some workers have a high potential for significant neutron exposure, the Savannah River Plant (SRP) contracted with Pacific Northwest Laboratory (PNL) to verify the accuracy of neutron dosimetry at the plant. Energy spectrum and neutron dose measurements were made at the SRP calibrations laboratory and at several other locations. The energy spectra measurements were made using multisphere or Bonner sphere spectrometers, 3 He spectrometers, and NE-213 liquid scintillator spectrometers. Neutron dose equivalent determinations were made using these instruments and others specifically designed to determine dose equivalent, such as the tissue equivalent proportional counter (TEPC). Survey instruments, such as the Eberline PNR-4, and the thermoluminescent dosimeter (TLD)-albedo and track etch dosimeters (TEDs) were also used. The TEPC, subjectively judged to provide the most accurate estimation of true dose equivalent, was used as the reference for comparison with other devices. 29 refs., 43 figs., 13 tabs

  1. High-energy, twelve-channel laser facility (DEFIN) for spherical irradiation of thermonuclear targets

    International Nuclear Information System (INIS)

    Basov, N.G.; Danilov, A.E.; Krokhin, O.N.; Kruglov, B.V.; Mikhailov, Yu.A.; Sklizkov, G.V.; Fedotov, S.I.; Fedorov, A.N.

    This paper describes a high-energy, twelve-channel laser facility (DELFIN) intended for high-temperature heating of thermonuclear targets with spherical symmetry. The facility includes a neodymium-glass laser with the ultimate radiation energy of 10 kJ, a pulse length of approximately 10 -10 to 10 -9 s, beam divergence of 5 x 10 -4 radians, a vacuum chamber in which laser radiation interacts with the plasma, and a system of diagnostic instrumentation for the observation of laser beam and plasma parameters. Described are the optical scheme and construction details of the laser facility. Presented is an analysis of focusing schemes for target irradiation and described is the focusing scheme of the DELFIN facility, which is capable of attaining a high degree of spherical symmetry in irradiating targets with maximum beam intensity at the target surface of approximately 10 15 W/cm 2 . This paper examines the most important problems connected with the physical investigations of thermonuclear laser plasma and the basic diagnostic problems involved in their solution

  2. Evaluation of the Neutron Detector Response for Cosmic Ray Energy Spectrum by Monte Carlo Transport Simulation

    International Nuclear Information System (INIS)

    Pazianotto, Mauricio T.; Carlson, Brett V.; Federico, Claudio A.; Gonzalez, Odair L.

    2011-01-01

    Neutrons generated by the interaction of cosmic rays with the atmosphere make an important contribution to the dose accumulated in electronic circuits and aircraft crew members at flight altitude. High-energy neutrons are produced in spallation reactions and intranuclear cascade processes by primary cosmic-ray particle interactions with atoms in the atmosphere. These neutrons can produce secondary neutrons and also undergo a moderation process due to atmosphere interactions, resulting in a wider energy spectrum, ranging from thermal energies (0.025 eV) to energies of several hundreds of MeV. The Long-Counter (LC) detector is a widely used neutron detector designed to measure the directional flux of neutrons with about constant response over a wide energy range (thermal to 20 MeV). ). Its calibration process and the determination of its energy response for the wide-energy of cosmic ray induced neutron spectrum is a very difficult process due to the lack of installations with these capabilities. The goal of this study is to assess the behavior of the response of a Long Counter using the Monte Carlo (MC) computational code MCNPX (Monte Carlo N-Particle eXtended). The dependence of the Long Counter response on the angle of incidence, as well as on the neutron energy, will be carefully investigated, compared with the experimental data previously obtained with 241 Am-Be and 252 Cf neutron sources and extended to the neutron spectrum produced by cosmic rays. (Author)

  3. Conceptual design of tritium production fusion reactor based on spherical torus

    International Nuclear Information System (INIS)

    He Kaihui; Huang Jinhua

    2003-01-01

    Conceptual design of an advanced tritium production fusion reactor based on spherical torus, which is intermediate application of fusion energy, was presented in this paper. Differing from the traditional tokamak tritium production reactor design, advanced plasma physics performance and compact structural characteristics of ST were used to minimize tritium leakage and maximize tritium breeding ratio with arrangement of tritium production blankets within vacuum vessel as possible in order to produce 1 kg excess tritium except need of self-sufficient plasma core with 40% or more corresponding plant availability. Based on 2D neutronics calculation, preliminary conceptual design of ST-TPR was presented, providing the backgrounds and reference for next detailed conceptual design

  4. Estimate of the damage in organs induced by neutrons in three-dimensional conformal radiotherapy; Estimacion del dano en organos inducido por neutrones en radioterapia conformada en 3D

    Energy Technology Data Exchange (ETDEWEB)

    Benites R, J. L. [Centro Estatal de Cancerologia de Nayarit, Servicio de Seguridad Radiologica, Calzada de la Cruz 118 sur, 63000 Tepic, Nayarit (Mexico); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Uribe, M. del R., E-mail: jlbenitesr@prodigy.net.mx [Instituto Tecnico Superior de Radiologia, Calle Leon No. 129, 63000 Tepic, Nayarit (Mexico)

    2014-08-15

    By means of Monte Carlo methods was considered the damage in the organs, induced by neutrons, of patients with cancer that receive treatment in modality of three-dimensional conformal radiotherapy (3D-CRT) with lineal accelerator Varian Ix. The objective of this work was to estimate the damage probability in radiotherapy patients, starting from the effective dose by neutrons in the organs and tissues out of the treatment region. For that a three-dimensional mannequin of equivalent tissue of 30 x 100 x 30 cm{sup 3} was modeled and spherical cells were distributed to estimate the Kerma in equivalent tissue and the absorbed dose by neutrons. With the absorbed dose the effective dose was calculated using the weighting factors for the organ type and radiation type. With the effective dose and the damage factors, considered in the ICRP 103, was considered the probability of damage induction in organs. (Author)

  5. Systematic studies of binding energy dependence of neutron-proton momentum correlation function

    International Nuclear Information System (INIS)

    Wei, Y B; Ma, Y G; Shen, W Q; Ma, G L; Wang, K; Cai, X Z; Zhong, C; Guo, W; Chen, J G; Fang, D Q; Tian, W D; Zhou, X F

    2004-01-01

    Hanbury Brown-Twiss (HBT) results of the neutron-proton correlation function have been systematically investigated for a series of nuclear reactions with light projectiles with the help of the isospin-dependent quantum molecular dynamics model. The relationship between the binding energy per nucleon of the projectiles and the strength of the neutron-proton HBT at small relative momentum has been obtained. Results show that neutron-proton HBT results are sensitive to the binding energy per nucleon

  6. Neutron radiography with ultracold neutrons

    International Nuclear Information System (INIS)

    Bates, J.C.

    1981-01-01

    The neutron transmission factor of very thin films may be low if the neutron energy is comparable to the pseudo-potential of the film material. Surprisingly, perhaps, it is relatively easy to obtain neutrons with such low energies in sufficient numbers to produce neutron radiographs. (orig.)

  7. Optimizing Laser-accelerated Ion Beams for a Collimated Neutron Source

    International Nuclear Information System (INIS)

    Ellison, C.L.; Fuchs, J.

    2010-01-01

    High-flux neutrons for imaging and materials analysis applications have typically been provided by accelerator- and reactor-based neutron sources. A novel approach is to use ultraintense (>1018W/cm2) lasers to generate picosecond, collimated neutrons from a dual target configuration. In this article, the production capabilities of present and upcoming laser facilities are estimated while independently maximizing neutron yields and minimizing beam divergence. A Monte-Carlo code calculates angular and energy distributions of neutrons generated by D-D fusion events occurring within a deuterated target for a given incident beam of D+ ions. Tailoring of the incident distribution via laser parameters and microlens focusing modifies the emerging neutrons. Projected neutron yields and distributions are compared to conventional sources, yielding comparable on-target fluxes per discharge, shorter time resolution, larger neutron energies and greater collimation.

  8. Development of neutron detectors and neutron radiography at ...

    Indian Academy of Sciences (India)

    BARC, Department of Atomic Energy units and some universities and research institutes in India and .... by Solid State Physics Division for various applications, using the 400 kW swim- ming pool type reactor, Apsara as the neutron source.

  9. Neutron-triton scattering lengths for interactions reproducing low-energy trinucleon data

    International Nuclear Information System (INIS)

    Levashev, V.P.

    1981-01-01

    By solving the integral equations for four nucleons the neutron-triton scattering lengths and total cross section are calculated using different S-wave rank-one separable potentials. A number of linear correlations between the neutron-triton scattering lengths and triton binding energy are found. The scattering lengths consistent with low-energy trinucleon data. The results obtained are compared with available experimental data [ru

  10. Neutrino-'pasta' scattering: The opacity of nonuniform neutron-rich matter

    International Nuclear Information System (INIS)

    Horowitz, C.J.; Perez-Garcia, M.A.; Piekarewicz, J.

    2004-01-01

    Neutron-rich matter at subnuclear densities may involve complex structures displaying a variety of shapes, such as spherical, slablike, and/or rodlike shapes. These phases of the nuclear pasta are expected to exist in the crust of neutron stars and in core-collapse supernovae. The dynamics of core-collapse supernovae is very sensitive to the interactions between neutrinos and nucleons/nuclei. Indeed, neutrino excitation of the low-energy modes of the pasta may allow for a significant energy transfer to the nuclear medium, thereby reviving the stalled supernovae shock. The linear response of the nuclear pasta to neutrinos is modeled via a simple semiclassical simulation. The transport mean free path for μ and τ neutrinos (and antineutrinos) is expressed in terms of the static structure factor of the pasta, which is evaluated using Metropolis Monte Carlo simulations

  11. Neutron-photon multigroup cross sections for neutron energies less than or equal to400 MeV. Revision 1

    International Nuclear Information System (INIS)

    Alsmiller, R.G. Jr.; Barnes, J.M.; Drischler, J.D.

    1986-01-01

    For a variety of applications, e.g., accelerator shielding design, neutrons in radiotherapy, radiation damage studies, etc., it is necessary to carry out transport calculations involving medium-energy (greater than or equal to20 MeV) neutrons. A previous paper described neutron-photon multigroup cross sections in the ANISN format for neutrons from thermal to 400 MeV. In the present paper the cross-section data presented previously have been revised to make them agree with available experimental data. 7 refs., 1 fig

  12. Neutron scattering investigation of magnetic excitations at high energy transfers

    International Nuclear Information System (INIS)

    Loong, C.K.

    1984-01-01

    With the advance of pulsed spallation neutron sources, neutron scattering investigation of elementary excitations in magnetic materials can now be extended to energies up to several hundreds of MeV. We have measured, using chopper spectrometers and time-of-flight techniques, the magnetic response functions of a series of d and f transition metals and compounds over a wide range of energy and momentum transfer. In PrO 2 , UO 2 , BaPrO 3 and CeB 6 we observed crystal-field transitions between the magnetic ground state and the excited levels in the energy range from 40 to 260 MeV. In materials exhibiting spin-fluctuation or mixed-valent character such as Ce 74 Th 26 , on the other hand, no sharp crystal-field lines but a broadened quasielastic magnetic peak was observed. The line width of the quasielastic component is thought to be connected to the spin-fluctuation energy of the 4f electrons. The significance of the neutron scattering results in relation to the ground state level structure of the magnetic ions and the spin-dynamics of the f electrons is discussed. Recently, in a study of the spin-wave excitations in itinerant magnetic systems, we have extended the spin-wave measurements in ferromagnetic iron up to about 160 MeV. Neutron scattering data at high energy transfers are of particular interest because they provide direct comparison with recent theories of itinerant magnetism. 26 references, 7 figures

  13. A parameter study to determine the optimal source neutron energy in boron neutron capture therapy of brain tumours

    Energy Technology Data Exchange (ETDEWEB)

    Nievaart, V A [Reactor Physics Department, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands); Moss, R L [Joint Research Centre of the European Commission, Postbus 2, 1755ZG Petten (Netherlands); Kloosterman, J L [Reactor Physics Department, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands); Hagen, T H J J van der [Reactor Physics Department, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands); Dam, H van [Reactor Physics Department, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands)

    2004-09-21

    The values of the parameters used in boron neutron capture therapy (BNCT) to calculate a given dose to human tissue vary with patients due to different physical, biological and/or medical circumstances. Parameters include the tissue dimensions, the {sup 10}B concentration and the relative biological effectiveness (RBE) factors for the different dose components associated with BNCT. Because there is still no worldwide agreement on RBE values, more often than not, average values for these parameters are used. It turns out that the RBE-problem can be circumvented by taking into account all imaginable parameter values. Approaching this quest from another angle: the outcome will also provide the parameters (and values) which influence the optimal source neutron energy. For brain tumours it turns out that the {sup 10}B concentration, the RBE factors for {sup 10}B as well as fast neutrons, together with the dose limit set for healthy tissue, affect the optimal BNCT source neutron energy. By using source neutrons of a few keV together with neutrons of a few eV, it ensures that, under all imaginable circumstances, a maximum of alpha (and lithium) particles can be delivered in the tumour.

  14. Broad Energy Range Neutron Spectroscopy using a Liquid Scintillator and a Proportional Counter: Application to a Neutron Spectrum Similar to that from an Improvised Nuclear Device.

    Science.gov (United States)

    Xu, Yanping; Randers-Pehrson, Gerhard; Marino, Stephen A; Garty, Guy; Harken, Andrew; Brenner, David J

    2015-09-11

    A novel neutron irradiation facility at the Radiological Research Accelerator Facility (RARAF) has been developed to mimic the neutron radiation from an Improvised Nuclear Device (IND) at relevant distances (e.g. 1.5 km) from the epicenter. The neutron spectrum of this IND-like neutron irradiator was designed according to estimations of the Hiroshima neutron spectrum at 1.5 km. It is significantly different from a standard reactor fission spectrum, because the spectrum changes as the neutrons are transported through air, and it is dominated by neutron energies from 100 keV up to 9 MeV. To verify such wide energy range neutron spectrum, detailed here is the development of a combined spectroscopy system. Both a liquid scintillator detector and a gas proportional counter were used for the recoil spectra measurements, with the individual response functions estimated from a series of Monte Carlo simulations. These normalized individual response functions were formed into a single response matrix for the unfolding process. Several accelerator-based quasi-monoenergetic neutron source spectra were measured and unfolded to test this spectroscopy system. These reference neutrons were produced from two reactions: T(p,n) 3 He and D(d,n) 3 He, generating neutron energies in the range between 0.2 and 8 MeV. The unfolded quasi-monoenergetic neutron spectra indicated that the detection system can provide good neutron spectroscopy results in this energy range. A broad-energy neutron spectrum from the 9 Be(d,n) reaction using a 5 MeV deuteron beam, measured at 60 degrees to the incident beam was measured and unfolded with the evaluated response matrix. The unfolded broad neutron spectrum is comparable with published time-of-flight results. Finally, the pair of detectors were used to measure the neutron spectrum generated at the RARAF IND-like neutron facility and a comparison is made to the neutron spectrum of Hiroshima.

  15. US progress on the development of CR-39 based neutron dosimeters

    International Nuclear Information System (INIS)

    Hadlock, D.E.

    1987-06-01

    Historically at US nuclear facilities, two types of personnel neutron dosimeters have been in routine use: nuclear track emulsion-Type A (NTA) film and thermoluminescent dosimeter (TLD)-albedo. Both of these dosimeters have energy-dependent responses. Therefore, the neutron energy spectra must be known, to interpret the dosimeter results properly. A new state-of-the-art dosimetry system has been developed within the US Department of Energy (US DOE) Personnel Neutron Dosimeter Evaluation and Upgrade Program. This system is called the combination thermoluminescent dosimeter/track etch dosimeter (TLD/TED). This paper briefly describes US DOE research currently being conducted to further enhance the TED portion of the combination TLD/TED system. The research areas involved include dose sensitivity, neutron energy range, specialized radiators, self-developing dosimeters, and neutron spectrometry. 1 fig., 1 tab

  16. Campbelling-type theory of fission chamber signals generated by neutron chains in a multiplying medium

    International Nuclear Information System (INIS)

    Pál, L.; Pázsit, I.

    2015-01-01

    The signals of fission chambers are usually evaluated with the help of the co-called Campbelling techniques. These are based on the Campbell theorem, which states that if the primary incoming events, generating the detector pulses, are independent, then relationships exist between the moments of various orders of the signal in the current mode. This gives the possibility to determine the mean value of the intensity of the detection events, which is proportional to the static flux, from the higher moments of the detector current, which has certain advantages. However, the main application area of fission chambers is measurements in power reactors where, as is well known, the individual detection events are not independent, due to the branching character of the neutron chains (neutron multiplication). Therefore it is of interest to extend the Campbelling-type theory for the case of correlated neutron events. Such a theory could address two questions: partly, to investigate the bias when the traditional Campbell techniques are used for correlated incoming events; and partly, to see whether the correlation properties of the detection events, which carry information on the multiplying medium, could be extracted from the measurements. This paper is devoted to the investigation of these questions. The results show that there is a potential possibility to extract the same information from fission chamber signals in the current mode as with the Rossi- or Feynman-alpha methods, or from coincidence and multiplicity measurements, which so far have required detectors working in the pulse mode. It is also shown that application of the standard Campbelling techniques to neutron detection in multiplying systems does not lead to an error for estimating the stationary flux as long as the detector is calibrated in in situ measurements

  17. Multiplicity and energy of neutrons from {sup 233}U(n{sub th},f) fission fragments

    Energy Technology Data Exchange (ETDEWEB)

    Nishio, Katsuhisa; Kimura, Itsuro; Nakagome, Yoshihiro [Kyoto Univ. (Japan)

    1998-03-01

    The correlation between fission fragments and prompt neutrons from the reaction {sup 233}U(n{sub th},f) was measured with improved accuracy. The results determined the neutron multiplicity and emission energy as a function of fragment mass and total kinetic energy. The average energy as a function of fragment mass followed a nearly symmetric distribution centered about the equal mass-split and formed a remarkable contrast with the saw-tooth distribution of the average neutron multiplicity. The neutron multiplicity from the specified fragment decreases linearly with total kinetic energy, and the slope of multiplicity with kinetic energy had the minimum value at about 130 u. The level density parameter versus mass determined from the neutron data showed a saw-tooth structure with the pronounced minimum at about 128 and generally followed the formula by Gilbert and Cameron, suggesting that the neutron emission process was very much affected by the shell-effect of the fission fragment. (author)

  18. Pilot study for the implantation of a high-energy neutrons field

    International Nuclear Information System (INIS)

    Pinto, Jose Julio de O.; Mendes, Adriane C.; Federico, Claudio A.; Passaro, Angelo; Gaspar, Felipe de B.; Pazianotto, Mauricio T.

    2013-01-01

    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

  19. Measurements of Relative Biological Effectiveness and Oxygen Enhancement Ratio of Fast Neutrons of Different Energies

    Energy Technology Data Exchange (ETDEWEB)

    Barendsen, G. W.; Broerse, J. J. [Radiobiological Institute of the Health Research Council TNO, Rijswijk (ZH) (Netherlands)

    1968-03-15

    Impairment of the reproductive capacity of cultured cells of human kidney origin (T-l{sub g} cells) has been measured by the Puck cloning technique. From the dose-survival curves obtained in these experiments by irradiation of cells in equilibrium with air and nitrogen, respectively, the relative biological effectiveness (RBE) and the oxygen enhancement ratios (OER) were determined for different beams of fast neutrons. Monoenergetic neutrons of 3 and 15 MeV energy, fission spectrum fast neutrons (mean energy about 1.5 MeV), neutrons produced by bombarding Be with cyclotron-accelerated 16 MeV deuterons (mean energy about 6 MeV) and neutrons produced by bombarding Be with cyclotron- accelerated 20 MeV {sup 3}He ions (mean energy about 10 MeV) have been compared with 250 kVp X-rays as a standard reference. The RBE for 50% cell survival varies from 4.7 for fission-spectrum fast neutrons to 2.7 for 15 MeV monoenergetic neutrons. The OER is not strongly dependent on the neutron energy for the various beams investigated. For the neutrons with the highest and lowest energies used OER values of 1.6 {+-} 0.2 and 1.5 {+-} 0.1 were measured. An interpretation of these data on the basis of the shapes of the LET spectra is proposed and an approximate verification of this hypothesis is provided from measurements in which secondary particle equilibrium was either provided for or deliberately eliminated. (author)

  20. Spherical shock due to point explosion with varying energy

    Science.gov (United States)

    Singh, J. B.; Srivastava, S. K.

    1983-05-01

    The motion of a perfect gas behind a weak or strong spherical point-explosion shock wave in a nonuniform rest atmosphere is investigated analytically for the case of variable flow energy. The self-similar solutions derived are also adaptable to a uniform expanding piston. The solution is applied to the isothermal case, and the results of numerical integration are presented in graphs showing the density, velocity, and pressure distributions for different values of delta. The findings are considered significant for investigations of sonic booms, laser production of plasmas, high-altitude nuclear detonations, supernova explosions, and the sudden expansion of the solar corona, and for the laboratory production of high temperatures using shock waves.