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Sample records for average prompt neutron

  1. Prompt fission neutron spectra and average prompt neutron multiplicities

    International Nuclear Information System (INIS)

    We present a new method for calculating the prompt fission neutron spectrum N(E) and average prompt neutron multiplicity anti nu/sub p/ as functions of the fissioning nucleus and its excitation energy. The method is based on standard nuclear evaporation theory and takes into account (1) the motion of the fission fragments, (2) the distribution of fission-fragment residual nuclear temperature, (3) the energy dependence of the cross section sigma/sub c/ for the inverse process of compound-nucleus formation, and (4) the possibility of multiple-chance fission. We use a triangular distribution in residual nuclear temperature based on the Fermi-gas model. This leads to closed expressions for N(E) and anti nu/sub p/ when sigma/sub c/ is assumed constant and readily computed quadratures when the energy dependence of sigma/sub c/ is determined from an optical model. Neutron spectra and average multiplicities calculated with an energy-dependent cross section agree well with experimental data for the neutron-induced fission of 235U and the spontaneous fission of 252Cf. For the latter case, there are some significant inconsistencies between the experimental spectra that need to be resolved. 29 references

  2. Reevaluation of the average prompt neutron emission multiplicity (nubar) values from fission of uranium and transuranium nuclides

    International Nuclear Information System (INIS)

    In response to a need of the safeguards community, we have begun an evaluation effort to upgrade the recommended values of the prompt neutron emission multiplicity distribution, P/sub nu/ and its average value, nubar. This paper will report on progress achieved thus far. The evaluation of the uranium, plutonium, americium and curium nuclide's nubar values will be presented. The recommended values will be given and discussed. 61 references

  3. Prompt neutron emission multiplicity distributions and average values, ν-bar, at 2200 meter per second for the fissile nuclides

    International Nuclear Information System (INIS)

    The prompt neutron emission multiplicity distribution, Pν, is of interest for methods of self-calibration and for auto-correlation to assay fissionable material for nuclear safeguards. ν-bar, the average value of Pν, is of interest at neutron thermal energies since it is related to the neutron multiplication factor and it is used as a normalizing point for energy dependent values of ν-bar. Values of Pν and ν-bar have been determined at the standard neutron energy of 0.0253 ev for the neutron induced fission of the four fissile nuclides, 233,235U, and 239,241Pu. Revised ν-bar values have been obtained by re-evaluating ν-bar experiments measured at 2200 meter/second relative to the ν-bar from the spontaneous fission of 252Cf. These revised values of ν-bar have been used to renormalize the measured Pν values. The revised values of ν-bar are all about 1/4 % to 1/2 % smaller than the corresponding values of ENDF/B-V. (author)

  4. Measurement of the neutron activity of a 252Cf source relative to the average number of prompt neutrons emitted per fission for the spontaneous fission

    International Nuclear Information System (INIS)

    A method was developed for measuring the absolute neutron activity of a large 252Cf source. The neutron counting assembly is composed of eight BF3 counters mounted in a large tank filled with water which is used as a moderator. The detection efficiency is determined using a low activity 252Cf source. The method is based on the identification of every fission event, followed by the counting of the fission neutrons detected by the BF3 counters during a time interval equal to the maximum neutron lifetime in the moderator. The efficiency is thus obtained relative to the average number of prompt neutrons emitted per 252Cf spontaneous fission which is commonly used as a standard. The measurement accuracy is estimated to be of the order of 1%

  5. Uranium and Plutonium Average Prompt-fission Neutron Energy Spectra (PFNS) from the Analysis of NTS NUEX Data

    Science.gov (United States)

    Lestone, J. P.; Shores, E. F.

    2014-05-01

    In neutron experiments (NUEX) conducted at the Nevada Test Site (NTS) by Los Alamos National Laboratory, the time-of-flight of fission-neutrons emitted from nuclear tests were observed by measuring the current generated by the collection of protons scattered from a thin CH2 foil many meters from the nuclear device into a Faraday cup. The time dependence of the Faraday cup current is a measure of the energy spectrum of the neutrons that leak from the device. With good device models and accurate neutron-transport codes, the leakage spectra can be converted into prompt fast-neutron-induced fission-neutron energy spectra. This has been done for two events containing plutonium, and for an earlier event containing uranium. The prompt-fission neutron spectra have been inferred for 1.5-MeV 239Pu(n,f) and 235U(n,f) reactions for outgoing neutron energies from 1.5 to ∼10.5 MeV, in 1-MeV steps. These spectra are in good agreement with the Los Alamos fission model.

  6. Prompt Neutrons from Fission

    International Nuclear Information System (INIS)

    A survey is given of the present state of knowledge of the spectrum, angular distribution and number of prompt fission neutrons, as functions of incident neutron energy and individual fragment mass, for low-energy fission. The energy spectrum of prompt neutrons has been found to be of the same form (nearly Maxwellian) for many different types of fission. It has been shown that this type of spectrum is to be expected on the basis of evaporation from moving fragments, and theoretical predictions of the spectrum agree very accurately with experimental data. Some data are now available on the variation of the neutron spectrum with fragment mass and angle of emission. Only recently has it become possible to take accurate data on the angular distribution of the neutrons. It appears that the neutrons have the angular distribution to be expected if emitted almost isotropically from the moving fragments, with a possibility that some small fraction are not emitted in this way, but directly from the fissioning nuclide. Much work has been done on the variation of fission neutron number v with incident neutron energy for neutron-induced fission. The neutron number increases roughly linearly with energy, with a slope of about 0.15 n/MeV. There is now evidence that this slope changes somewhat with energy. This change must be associated with other changes in the-fission process. The most interesting recent discovery concerning fission neutrons is the strong dependence of neutron number on individual fragment mass. The data are being rapidly improved by means of the newer techniques of determining fragment mass yields from velocity and pulse-height data, and of determining neutron yields from cumulative mass yields. There is evidence of similar dependence of neutron yield on fragment mass in a number of cases. It has been suggested that this property is directly connected with the deformability of the fragments, and in particular with the near-spherical shapes of magic

  7. Neutron resonance averaging

    International Nuclear Information System (INIS)

    The principles of resonance averaging as applied to neutron capture reactions are described. Several illustrations of resonance averaging to problems of nuclear structure and the distribution of radiative strength in nuclei are provided. 30 refs., 12 figs

  8. Prompt neutron multiplicities for the transplutonium nuclides

    International Nuclear Information System (INIS)

    In reponse to a need of the safeguards community, we have begun an evaluation effort to upgrade the values of the prompt neutron emission multiplicity distribution from fission, Psub(upsilon), and its average value . The reported Psub(upsilon) for various transplutonium nuclides have been renormalized via an independent evaluation of . Recommended values and uncertainties are given for the newly evaluated and Psub(upsilon). (author)

  9. Prompt neutron multiplicities for the transplutonium nuclides

    International Nuclear Information System (INIS)

    The direct determination of the average prompt neutron emission values is reviewed, and a method of comparing different sites of neutron emission multiplicity distribution values is described. Measured and recommended values are tabulated for these nuclides: 241Am, 242Am, 242Cm, 243Cm, 244Cm, 246Cm, 247Cm, 248Cm, 250Cm, 245Cm, 249Bk, 246Cf, 249Cf, 250Cf, 252Cf, 254Cf, 251Cf, 253Es, 254Es, 244Fm, 246Fm, 255Fm, 252No, 254Fm, 256Fm, 257Fm. 59 refs., 24 tabs

  10. Prompt fission neutron spectrum of actinides

    Energy Technology Data Exchange (ETDEWEB)

    Capote, R. [International Atomic Energy Agency, Vienna (Austria); Chen, Y. -J. [China Institute of Atomic Energy, Beijing (China); Hambsch, F. J. [European Commission, Joint Research Centre - IRRM, Geel (Belgium); Jurado, B. [CENBG, CNRS/IN2P3, Gradignan (France); Kornilov, N. [Ohio Univ., Athens, OH (United States); Lestone, J. P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Litaize, O. [CEA, DEN, DER, SPRC, Saint-Paul-Lez-Durance (France); Morillon, B. [CEA, DAM, DIF, Arpajon (France); Neudecker, D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oberstedt, S. [European Commission, Joint Research Centre - IRRM, Geel (Belgium); Ohsawa, T. [Kinki Univ., Osaka-fu (Japan); Otuka, N. [International Atomic Energy Agency, Vienna (Austria); Pronyaev, V. G. [Institute of Physics and Power Engineering, Obninsk (Russian Federation); Saxena, A. [Bhabha Atomic Research Centre, Mumbai (India); Schmidt, K. H. [CENBG, CNRS/IN2P3, Gradignan (France); Serot, O. [CEA, DEN, DER, SPRC, Saint-Paul-Lez-Durance (France); Shcherbakov, O. A. [Petersburg Nuclear Physics Institute of NRC " Kurchatov Institute" , Gatchina (Russian Federation); Shu, N. -C. [China Institute of Atomic Energy, Beijing (China); Smith, D. L. [Argonne National Lab. (ANL), Argonne, IL (United States); Talou, P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Trkov, A. [International Atomic Energy Agency, Vienna (Austria); Tudora, A. C. [Univ. of Bucharest, Magurele (Romania); Vogt, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of California, Davis, CA (United States); Vorobyev, A. S. [Petersburg Nuclear Physics Institute of NRC " Kurchatov Institute" , Gatchina (Russian Federation)

    2016-01-06

    Here, the energy spectrum of prompt neutron emitted in fission (PFNS) plays a very important role in nuclear science and technology. A Coordinated Research Project (CRP) "Evaluation of Prompt Fission Neutron Spectra of Actinides" was established by the IAEA Nuclear Data Section in 2009, with the major goal to produce new PFNS evaluations with uncertainties for actinide nuclei.

  11. Prompt Emission in Fission Induced with Fast Neutrons

    Science.gov (United States)

    Wilson, J. N.; Lebois, M.; Halipré, P.; Oberstedt, S.; Oberstedt, A.

    Prompt gamma-ray and neutron emission data in fission integrates a large amount of information on the fission process and can shed light on the partition of energy. Measured emission spectra, average energies and multiplicities also provide important information for energy applications. While current reactors mostly use thermal neutron spectra, the future reactors of Generation IV will use fast neutron spectra for which little experimental prompt emission data exist. Initial investigations on prompt emission in fast neutron induced fission have recently been carried out at the LICORNE facility at the IPN Orsay, which exploits inverse reactions to produce naturally collimated, intense beams of neutrons. We report on first results with LICORNE to measure prompt fission gamma-ray spectra, average energies and multiplicities for 235U and 238U. Current improvements and upgrades being carried out on the LICORNE facility will also be described, including the development of a H2 gas target to reduce parasitic backgrounds and increase intensities, and the deployment of 11B beams to extend the effective LICORNE neutron energy range up to 12 MeV. Prospects for future experimental studies of prompt gamma-ray and neutron emission in fast neutron induced fission will be presented.

  12. Prompt Fission Neutron Spectra of Actinides

    Energy Technology Data Exchange (ETDEWEB)

    Capote, R; Chen, Y J; Hambsch, F J; Kornilov, N V; Lestone, J P; Litaize, O; Morillon, B; Neudecker, D; Oberstedt, S; Ohsawa, T; Smith, D. L.

    2016-01-01

    The energy spectrum of prompt neutrons emitted in fission (PFNS) plays a very important role in nuclear science and technology. A Coordinated Research Project (CRP) “Evaluation of Prompt Fission Neutron Spectra of Actinides”was established by the IAEA Nuclear Data Section in 2009, with the major goal to produce new PFNS evaluations with uncertainties for actinide nuclei. The following technical areas were addressed: (i) experiments and uncertainty quantification (UQ): New data for neutron-induced fission of 233U, 235U, 238U, and 239Pu have been measured, and older data have been compiled and reassessed. There is evidence from the experimental work of this CRP that a very small percentage of neutrons emitted in fission are actually scission neutrons; (ii) modeling: The Los Alamos model (LAM) continues to be the workhorse for PFNS evaluations. Monte Carlo models have been developed that describe the fission phenomena microscopically, but further development is needed to produce PFNS evaluations meeting the uncertainty targets; (iii) evaluation methodologies: PFNS evaluations rely on the use of the least-squares techniques for merging experimental and model data. Considerable insight was achieved on how to deal with the problem of too small uncertainties in PFNS evaluations. The importance of considering that all experimental PFNS data are “shape” data was stressed; (iv) PFNS evaluations: New evaluations, including covariance data, were generated for major actinides including 1) non-model GMA evaluations of the 235U(nth,f), 239Pu(nth,f), and 233U(nth,f) PFNS based exclusively on experimental data (0.02 ≤ E ≤ 10 MeV), which resulted in PFNS average energies E of 2.00±0.01, 2.073±0.010, and 2.030±0.013 MeV, respectively; 2) LAM evaluations of neutron-induced fission spectra on uranium and plutonium targets with improved UQ for incident energies from thermal up to 30 MeV; and 3) Point-by-Point calculations for 232Th, 234U and 237Np targets; and (v) data

  13. Prompt Neutron Lifetime for the NBSR Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, A.L.; Diamond, D.

    2012-06-24

    In preparation for the proposed conversion of the National Institute of Standards and Technology (NIST) research reactor (NBSR) from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel, certain point kinetics parameters must be calculated. We report here values of the prompt neutron lifetime that have been calculated using three independent methods. All three sets of calculations demonstrate that the prompt neutron lifetime is shorter for the LEU fuel when compared to the HEU fuel and longer for the equilibrium end-of-cycle (EOC) condition when compared to the equilibrium startup (SU) condition for both the HEU and LEU fuels.

  14. Research on Prompt Neutron Multiplicity Distribution at Thermal Neutrons

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The prompt neutron multiplicity distribution as a function of mass of fission fragments ν(A) was studied using the semi-empirical method of excitation energy distributions between the two fission

  15. Energy Correlation of Prompt Fission Neutrons

    Science.gov (United States)

    Elter, Zs.; Pázsit, I.

    2016-03-01

    In all cases where neutron fluctuations in a branching process (such as in multiplicity measurements) are treated in an energy dependent description, the energy correlations of the branching itself (energy correlations of the fission neutrons) need to be known. To date, these are not known from experiments. Such correlations can be theoretically and numerically derived by modelling the details of the fission process. It was suggested earlier that the fact that the prompt neutrons are emitted from the moving fission targets, will influence their energy and angular distributions in the lab system, which possibly induces correlations. In this paper the influence of the neutron emission process from the moving targets on the energy correlations is investigated analytically and via numerical simulations. It is shown that the correlations are generated by the random energy and direction distributions of the fission fragments. Analytical formulas are derived for the two-point energy distributions, and quantitative results are obtained by Monte-Carlo simulations. The results lend insight into the character of the two-point distributions, and give quantitative estimates of the energy correlations, which are generally small.

  16. Energy Correlation of Prompt Fission Neutrons

    Directory of Open Access Journals (Sweden)

    Elter Zs.

    2016-01-01

    Full Text Available In all cases where neutron fluctuations in a branching process (such as in multiplicity measurements are treated in an energy dependent description, the energy correlations of the branching itself (energy correlations of the fission neutrons need to be known. To date, these are not known from experiments. Such correlations can be theoretically and numerically derived by modelling the details of the fission process. It was suggested earlier that the fact that the prompt neutrons are emitted from the moving fission targets, will influence their energy and angular distributions in the lab system, which possibly induces correlations. In this paper the influence of the neutron emission process from the moving targets on the energy correlations is investigated analytically and via numerical simulations. It is shown that the correlations are generated by the random energy and direction distributions of the fission fragments. Analytical formulas are derived for the two-point energy distributions, and quantitative results are obtained by Monte-Carlo simulations. The results lend insight into the character of the two-point distributions, and give quantitative estimates of the energy correlations, which are generally small.

  17. Advanced modeling of prompt fission neutrons and gamma rays

    International Nuclear Information System (INIS)

    Prompt fission neutrons and gamma rays are computed using a Monte Carlo treatment of the statistical evaporation of the excited primary fission fragments. The assumption of two fragments in thermal equilibrium at the time of neutron emission is addressed by studying the neutron multiplicity as a function of fragment mass. Results for the neutron-induced fission of 235U are discussed, for incident neutron energies from 0.5 to 5.5 MeV. Recent experimental data on the fission fragment yields as a function of mass and total kinetic energy are used as input data. Monte-Carlo calculations allow the exploration of physical observables beyond average quantities. A new parameter RT has been introduced: RT=Tl/Th where Tl and Th are the temperatures in the light and heavy fragments. The average neutron multiplicity computed as a function of the fragment mass agrees best with the experimental data (with En=5.5 MeV) when RT=1 which can be understood as follows: as the incident neutron energy increases, the role of shell effects diminishes and the ratio of collective energies stored in the light and heavy fragment tends toward 1

  18. Prompt neutron multiplicity distribution for 235U(n,f) at incident energies up to 20 MeV

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-Jing; LIU Ting-Jin

    2011-01-01

    For the n+U fission reaction, the total excitation energy partition of the fission fragments, the average neutron kinetic energy (A) and the total average energies E(A) removed by γ rays as a function of fission fragment mass are given at incident energies up to 20 MeV. The prompt neutron multiplicity as a function of the fragment mass, ν(A), for neutron-induced fission of U at different incident neutron energies is calculated. The calculated results are checked with the total average prompt neutron multiplicities ν and compared with the experimental and evaluated data. Some prompt neutron and γ emission mechanisms are discussed.

  19. Multi-modal calculations of prompt fission neutrons from 238U(n, f) at low induced energy

    Institute of Scientific and Technical Information of China (English)

    ZHENG Na; ZHONG Chun-Lai; FAN Tie-Shuan

    2011-01-01

    Properties of prompt fission neutrons from 238U(n,f) are calculated for incident neutron energies below 6 MeV using the multi-modal model,including the prompt fission neutron spectrum,the average prompt fission neutron multiplicity,and the prompt fission neutron multiplicity as a function of the fission fragment mass v(A) (usually named “sawtooth” data) The three most dominant fission modes are taken into account.The model parameters are determined on the basis of experimental fission fragment data.The predicted results are in good agreement with the experimental data.

  20. Lifetime measurement of prompt neutrons using the neutronic noise analysis

    International Nuclear Information System (INIS)

    The purpose of this work is to estimate the life of the prompt neutrons, i, of a nuclear reactor utilizing the neutron noise analysis. This technique carry to development of mathematical model that is valid for lower powers reactor. The equation resulting convey to the observation about power spectrum behaviour respect to the frecquency. In this case, the reactor in study is the Triga Mark III of Nuclear Center of Mexico that it was provided of fission chambers for register the neutron fluxes. These fluxes was digitized and storage in computer disc as signals dependents of time, for later apply the Fourier Transformation and obtain the spectras. The spectras measured to different reactor powers were adjusted to the development equation before, using the method of square minimum and so estimate the parameter i. The analysis of results throw a value of 22.73 +/- 0.92 μs. On the other hand, the calculate value to the resolve the kinetic equation of reactor defer in lower than 4 % about the estimate. Of this, it concludes that the model utilized is trusty with a good mistake margin, moreover of that the technique of Neutron Noise analysis demonstrate be competitive (Author)

  1. Introduction of Prompt Gamma Thermal Neutron Activation Analysis at CARR

    Institute of Scientific and Technical Information of China (English)

    WANG; Xing-hua; XIAO; Cai-jin; ZHANG; Gui-ying; YAO; Yong-gang; JIN; Xiang-chun; WANG; Ping-sheng; HUA; Long; NI; Bang-fa

    2013-01-01

    CARR will provide with maximal neutron flux in Asia,the third of the world.By using the high quality neutron beam and the advanced international experience,Prompt Gamma Neutron Activation Analysis(PGNAA)facility will be setup at high level.PGNAA on CARR will promote the development of nuclear analysis technology and improve Chinese status in the nuclear analysis field.

  2. Modelling of reaction cross sections and prompt neutron emission

    Science.gov (United States)

    Hambsch, F.-J.; Tudora, A.; Oberstedt, S.

    2010-10-01

    Accurate nuclear data concerning reaction cross sections and the emission of prompt fission neutrons (i.e. multiplicity and spectra) as well as other fission fragment data are of great importance for reactor physics design, especially for the new Generation IV nuclear energy systems. During the past years for several actinides (238U(n, f) and 237Np(n, f)) both the reaction cross sections and prompt neutron multiplicities and spectra have been calculated within the frame of the EFNUDAT project.

  3. Modelling of reaction cross sections and prompt neutron emission

    OpenAIRE

    Oberstedt S.; Tudora A.; Hambsch F.-J.

    2010-01-01

    Accurate nuclear data concerning reaction cross sections and the emission of prompt fission neutrons (i.e. multiplicity and spectra) as well as other fission fragment data are of great importance for reactor physics design, especially for the new Generation IV nuclear energy systems. During the past years for several actinides (238U(n, f) and 237Np(n, f)) both the reaction cross sections and prompt neutron multiplicities and spectra have been calculated within the frame of the EFNUDAT project.

  4. Theoretical description of prompt neutron multiplicity and spectra

    International Nuclear Information System (INIS)

    The present work concerns two of successful models used today: PbP (Point by Point) and the Monte-Carlo approaches for providing all quantities characterizing the prompt neutron and gamma-ray emission. Therefore the thesis is structured as described below. The description of the PbP model and of the extended Los Alamos model for higher energies that takes into account the secondary chains and ways is given in Chapter II. In this chapter are detailed also examples of PbP and most probable fragmentation approach calculations for various quantities which characterize prompt emission: multi-parametric matrices [meaning different quantities as a function of fragment and of TKE (Total Kinetic Energy of the fission fragments)], quantities as a function of fragment mass, quantities as a function of the TKE and total average quantities, for different spontaneous and neutron induced fissioning systems. Special care was given to the TXE (Total Excitation Energy) partition between the fully accelerated fission fragments, two partition methods used in the PbP model being discussed in details. In Chapter III is given the description of the Monte Carlo treatment included in the FIFRELIN code. Only those aspects that differ from the PbP treatment are emphasized, namely the treatment of the moment of inertia entering the rotational energy calculation and the TXE partition method based on a mass dependent temperature ratio law. A special attention is given to the latest developments of the code concerning the inclusion of the energy dependent compound nucleus cross-section of the inverse process of neutron evaporation from fragments. In this chapter examples of calculation with the FIFRELIN code for the case of the standard fissioning system 252Cf (SF) are given. Original results for several plutonium spontaneous fissioning systems (236,238,240,242,244Pu) and one neutron induced fissioning system (239Pu(nth,f)) obtained with both PbP and Monte-Carlo treatments are given in Chapter

  5. Modelling of reaction cross sections and prompt neutron emission

    Directory of Open Access Journals (Sweden)

    Oberstedt S.

    2010-10-01

    Full Text Available Accurate nuclear data concerning reaction cross sections and the emission of prompt fission neutrons (i.e. multiplicity and spectra as well as other fission fragment data are of great importance for reactor physics design, especially for the new Generation IV nuclear energy systems. During the past years for several actinides (238U(n, f and 237Np(n, f both the reaction cross sections and prompt neutron multiplicities and spectra have been calculated within the frame of the EFNUDAT project.

  6. Measurement of prompt neutron multiplication on the zero power

    International Nuclear Information System (INIS)

    Using a set of ST-PMT detector, the prompt neutron multiplication on the zero power is measured by the reliable and effective shielding methods. The results are compared with the results of Rossi-α method and 252Cf fission chamber technique. (authors)

  7. Calculation of prompt neutron spectra for curium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ohsawa, Takaaki [Kinki Univ., Higashi-Osaka, Osaka (Japan). Atomic Energy Research Inst.

    1997-03-01

    With the aim of checking the existing evaluations contained in JENDL-3.2 and providing new evaluations based on a methodology proposed by the author, a series of calculations of prompt neutron spectra have been undertaken for curium isotopes. Some of the evaluations in JENDL-3.2 was found to be unphysically hard and should be revised. (author)

  8. Neutron fluence rate measurement using prompt gamma rays

    International Nuclear Information System (INIS)

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

  9. Prompt γ-ray analysis with reactor neutrons (review)

    International Nuclear Information System (INIS)

    A neutron-induced prompt γ-ray analysis (PGA) has recently evolved as a non-destructive analytical method which can determine light elements, such as H and B, and multi-elements as a result of increased analytical sensitivities by using low-energy guided neutron beams of nuclear reactors. Firstly, the principle, characteristics and history of reactor neutron-based PGA is described; then, the characteristics of PGA systems which are classified into internal, beam and guided beam types are described. Moreover, the basics and standardization for the elemental determination in PGA are described and various applications of PGA are reviewed. Finally, micro-sample, spot spatial-distribution analyses of elements using a cold-neutron micro beam produced by a neutron lens are described and the future development of the method is predicted. (author)

  10. Investigation of the prompt-neutron spectrum for spontaneously-fissioning /sup 252/Cf

    Energy Technology Data Exchange (ETDEWEB)

    Poenitz, W.P.; Tamura, T.

    1982-01-01

    The prompt-fission-neutron spectrum of /sup 252/Cf was investigated. The spectrum was measured with Black Neutron Detectors which have a well known efficiency. Considerations of various issues in such measurements lead to an experiment in which a time-calibration pulser, a random pulser, the neutron detector time-of-flight spectrum, the pulse-shape-discriminator gamma time-of-flight spectrum, and the detector-response spectra were simultaneously recorded for the prompt-fission neutrons, transmission through carbon, and shadowbars in a total-cross-section-type measurement. Corrections and associated uncertainties were applied for a large variety of effects which may have been overlooked in many of the previously reported measurements. Preliminary results indicate deviations from a Maxwellian shape toward a Watt-spectrum shape. Agreement is good with the shape differences relative to a Maxwellian from the recent theoretical calculation by Madland and Nix, however, a lower average energy was found.

  11. Investigation of the prompt-neutron spectrum for spontaneously-fissioning 252Cf

    International Nuclear Information System (INIS)

    The prompt-fission-neutron spectrum of 252Cf was investigated. The spectrum was measured with Black Neutron Detectors which have a well known efficiency. Considerations of various issues in such measurements lead to an experiment in which a time-calibration pulser, a random pulser, the neutron detector time-of-flight spectrum, the pulse-shape-discriminator gamma time-of-flight spectrum, and the detector-response spectra were simultaneously recorded for the prompt-fission neutrons, transmission through carbon, and shadowbars in a total-cross-section-type measurement. Corrections and associated uncertainties were applied for a large variety of effects which may have been overlooked in many of the previously reported measurements. Preliminary results indicate deviations from a Maxwellian shape toward a Watt-spectrum shape. Agreement is good with the shape differences relative to a Maxwellian from the recent theoretical calculation by Madland and Nix, however, a lower average energy was found

  12. The 235U Prompt Fission Neutron Spectrum in the BR1 Reactor at SCK•CEN

    Directory of Open Access Journals (Sweden)

    Wagemans Jan

    2016-01-01

    Full Text Available The BR1 research reactor at SCK•CEN has a spherical cavity in the graphite above the reactor core. In this cavity an accurately characterised Maxwellian thermal neutron field is present. Different converters can be loaded in the cavity in order to obtain other types of neutron (and gamma irradiation fields. Inside the so-called MARK III converter a fast 235U(n,f prompt fission neutron field can be obtained. With the support of MCNP calculations, irradiations in MARK III can be directly related to the pure 235U(n,f prompt fission neutron spectrum. For this purpose MARK III spectrum averaged cross sections for the most relevant fluence dosimetry reactions have been determined. A calibration factor for absolute measurements has been determined applying activation dosimetry following ISO/IEC 17025 standards.

  13. The 235U Prompt Fission Neutron Spectrum in the BR1 Reactor at SCK•CEN

    Science.gov (United States)

    Wagemans, Jan; Malambu, Edouard; Borms, Luc; Fiorito, Luca

    2016-02-01

    The BR1 research reactor at SCK•CEN has a spherical cavity in the graphite above the reactor core. In this cavity an accurately characterised Maxwellian thermal neutron field is present. Different converters can be loaded in the cavity in order to obtain other types of neutron (and gamma) irradiation fields. Inside the so-called MARK III converter a fast 235U(n,f) prompt fission neutron field can be obtained. With the support of MCNP calculations, irradiations in MARK III can be directly related to the pure 235U(n,f) prompt fission neutron spectrum. For this purpose MARK III spectrum averaged cross sections for the most relevant fluence dosimetry reactions have been determined. A calibration factor for absolute measurements has been determined applying activation dosimetry following ISO/IEC 17025 standards.

  14. Theoretical description of prompt fission neutron multiplicity and spectra

    CERN Document Server

    Manailescu, Cristian

    2014-01-01

    The present work concerns two successful models used today: Point by Point (PbP) and the Monte Carlo approaches. The description of the PbP model and of the extended Los Alamos model for higher energies that takes into account the secondary chains and ways is given in Chapter II. In this chapter are given also examples of PbP and most probable fragmentation approach calculations for various quantities which characterize prompt emission: multi-parametric matrices, quantities as a function of fragment mass, quantities as a function of the TKE and total average quantities, for different spontaneous and neutron induced fissioning systems. Special care was given to the TXE partition between the fully accelerated fission fragments, two partition methods used in the PbP model being discussed in details. In Chapter III is given the description of the Monte Carlo treatment included in the FIFRELIN code. Only those aspects that differ from the PbP treatment are emphasized. A special attention is given to the latest dev...

  15. Introducing Nuclear Data Evaluations of Prompt Fission Neutron Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Neudecker, Denise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-06-17

    Nuclear data evaluations provide recommended data sets for nuclear data applications such as reactor physics, stockpile stewardship or nuclear medicine. The evaluated data are often based on information from multiple experimental data sets and nuclear theory using statistical methods. Therefore, they are collaborative efforts of evaluators, theoreticians, experimentalists, benchmark experts, statisticians and application area scientists. In this talk, an introductions is given to the field of nuclear data evaluation at the specific example of a recent evaluation of the outgoing neutron energy spectrum emitted promptly after fission from 239Pu and induced by neutrons from thermal to 30 MeV.

  16. Calculation of prompt fission neutron spectra for 235U(n,f)

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-Jing; JIA Min; TAO Xi; QIAN Jing; LIU Ting-Jin; SHU Neng-Chuan

    2012-01-01

    The prompt fission neutron spectra for the neutron-induced fission of 235U at En < 5 MeV are calculated using nuclear evaporation theory with a semi-empirical model,in which the nonconstant and constant temperatures related to the Fermi gas model are taken into account. The calculated prompt fission neutron spectra reproduce the experimental data well.For the n(thermal)+235U reaction,the average nuclear temperature of the fission fragment,and the probability distribution of the nuclear temperature,are discussed and compared with the Los Alamos model.The energy carried away by γ rays emitted from each fragment is also obtained and the results are in good agreement with the existing experimental data.

  17. The MUSE-4 experiment: prompt reactivity and neutron spectrum measurements

    International Nuclear Information System (INIS)

    In the case of the use of ADS for incineration of nuclear waste and energy production a better knowledge of the ways to monitor the different reactor parameters is required. To do so, the MASURCA fast neutron reactor in different subcritical configurations has been coupled to a deuteron accelerator producing a pulse of neutrons in the middle of the core. We performed both dynamic and spectroscopic measurements. First, the time response of the core after a pulse is measured with a 235U fission chamber and a 3He proportional counter. We show that for a core close to criticality the neutron population behaves as predicted by the point kinetics theory. On the other hand, for subcriticality level relevant for ADS, the evolution of the neutron population is not a pure exponential and thus the point kinetics cannot be used to deduce the prompt multiplication factor. So we propose a new approach based partly on MCNP simulations and with less restrictive assumptions than those of the point kinetics. This method allows a determination of different prompt k values which are in good agreement with the expected ones. Spectroscopic measurements are also performed with a 3He proportional counter. From the specific response of the detector to monoenergetic neutrons it is possible to reconstruct the neutron energy spectrum at the detector location, which is found in good agreement with the simulated one below 0.6 MeV. Above this energy some studies are in progress to improve the detector response. These very preliminary results will be completed by further tests and experiments planned till the end of 2003. (authors)

  18. Research on Prompt Neutron Multiplicity Distribution for the Neutron-Induced Fission of 235U at 14 MeV Neutrons

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The prompt neutron multiplicity distribution ν(A) for the n+ 235U fission system at 14 MeV was studied using the distribution mode of the excitation energy and the averaged γ-ray energy in the two

  19. Optimization study of epithermal neutron detector in prompt fission neutron uranium logging

    International Nuclear Information System (INIS)

    Background: Prompt fission neutron uranium logging is a method for uranium exploration. Pulsed neutron source and epithermal neutron detector are used to detect the prompt epithermal neutron from the fission of thermal neutron and 235U. Purpose: The efficiency of epithermal neutron detector of the logging instrument need to be improved. Methods: The energy distribution of fission neutron detected by the epithermal neutron detector, as well as the detection efficiency of epithermal neutron detector with different sizes of moderator are studied by Monte Carlo simulation. Results: Under the studied conditions, the optimal sizes of neutron moderating material and neutron detector are obtained, which is the combination of 0.5-mm thick cadmium, 1.1-cm thick polyethylene and 2.6-cm diameter 3He tube. Conclusions: In the space with outer diameter of 4.8 cm, the maximum of the epithermal neutron detection efficiency was achieved by combination of a 1.1-cm thick tube and a 2.6-cm diameter 3He moderator when using polyethylene or organic glass as the moderator material. (authors)

  20. Simultaneous measurement of fission fragments and prompt neutrons for thermal neutron-induced fission of U-235

    Energy Technology Data Exchange (ETDEWEB)

    Nishio, Katsuhisa; Yamamoto, Hideki; Kimura, Itsuro; Nakagome, Yoshihiro [Kyoto Univ. (Japan)

    1997-03-01

    Simultaneous measurement of fission fragments and prompt neutrons following the thermal neutron induced fission of U-235 has been performed in order to obtain the neutron multiplicity (v) and its emission energy ({eta}) against the specified mass (m{sup *}) and the total kinetic energy (TKE). The obtained value of -dv/dTKE(m{sup *}) showed a saw-tooth distribution. The average neutron energy <{eta}>(m{sup *}) had a distribution with a reflection symmetry around the half mass division. The measurement also gave the level density parameters of the specified fragment, a(m{sup *}), and this parameters showed a saw-tooth trend too. The analysis by a phenomenological description of this parameters including the shell and collective effects suggested the existence of a collective motion of the fission fragments. (author)

  1. Partial neutron capture cross sections of actinides using cold neutron prompt gamma activation analysis

    International Nuclear Information System (INIS)

    Nuclear waste needs to be characterized for its safe handling and storage. In particular long-lived actinides render the waste characterization challenging. The results described in this thesis demonstrate that Prompt Gamma Neutron Activation Analysis (PGAA) with cold neutrons is a reliable tool for the non-destructive analysis of actinides. Nuclear data required for an accurate identification and quantification of actinides was acquired. Therefore, a sample design suitable for accurate and precise measurements of prompt γ-ray energies and partial cross sections of long-lived actinides at existing PGAA facilities was presented. Using the developed sample design the fundamental prompt γ-ray data on 237Np, 241Am and 242Pu were measured. The data were validated by repetitive analysis of different samples at two individual irradiation and counting facilities - the BRR in Budapest and the FRM II in Garching near Munich. Employing cold neutrons, resonance neutron capture by low energetic resonances was avoided during the experiments. This is an improvement over older neutron activation based works at thermal reactor neutron energies. 152 prompt γ-rays of 237Np were identified, as well as 19 of 241Am, and 127 prompt γ-rays of 242Pu. In all cases, both high and lower energetic prompt γ-rays were identified. The most intense line of 237Np was observed at an energy of Eγ=182.82(10) keV associated with a partial capture cross section of σγ=22.06(39) b. The most intense prompt γ-ray lines of 241Am and of 242Pu were observed at Eγ=154.72(7) keV with σγ=72.80(252) b and Eγ=287.69(8) keV with σγ=7.07(12) b, respectively. The measurements described in this thesis provide the first reported quantifications on partial radiative capture cross sections for 237Np, 241Am and 242Pu measured simultaneously over the large energy range from 45 keV to 12 MeV. Detailed uncertainty assessments were performed and the validity of the given uncertainties was demonstrated. Compared

  2. Application of inelastic neutron scattering and prompt neutron activation analysis in coal quality assessment

    International Nuclear Information System (INIS)

    The basic principles are assessed of the determination of ash content in coal based on the measurement of values proportional to the effective proton number. Discussed is the principle of coal quality assessment using the method of inelastic neutron scattering and prompt neutron activation analysis. This is done with respect both to theoretical relations between measured values and coal quality attributes and to practical laboratory measurements of coal sample quality by the said methods. (author)

  3. Coincidence Prompt Gamma-Ray Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    R.P. gandner; C.W. Mayo; W.A. Metwally; W. Zhang; W. Guo; A. Shehata

    2002-11-10

    The normal prompt gamma-ray neutron activation analysis for either bulk or small beam samples inherently has a small signal-to-noise (S/N) ratio due primarily to the neutron source being present while the sample signal is being obtained. Coincidence counting offers the possibility of greatly reducing or eliminating the noise generated by the neutron source. The present report presents our results to date on implementing the coincidence counting PGNAA approach. We conclude that coincidence PGNAA yields: (1) a larger signal-to-noise (S/N) ratio, (2) more information (and therefore better accuracy) from essentially the same experiment when sophisticated coincidence electronics are used that can yield singles and coincidences simultaneously, and (3) a reduced (one or two orders of magnitude) signal from essentially the same experiment. In future work we will concentrate on: (1) modifying the existing CEARPGS Monte Carlo code to incorporate coincidence counting, (2) obtaining coincidence schemes for 18 or 20 of the common elements in coal and cement, and (3) optimizing the design of a PGNAA coincidence system for the bulk analysis of coal.

  4. Evaluation of prompt neutron spectra for minor actinide nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ohsawa, Takaaki [Kinki Univ., Higashi-Osaka, Osaka (Japan). Atomic Energy Research Inst.

    1997-03-01

    Measurement data on fission prompt neutron spectra of minor actinide (MA) is much little, and its accuracy is also unsufficient. Therefore, conventional evaluation value of fission spectra of MA was assumed for its nuclear temperature by using a method of determining from its systemicity owing to assumption of the Maxwell type distribution, but it can be said that this method consider fully to features of MA isotopes. In this paper, some evaluation calculation results are shown by adopting an evaluation method developed by authors and based on modified Madland Nix model and are conducted by concept of physical properties on target nuclei. As a result, by adopting the level density parameter of fission fragments, the inverse process cross section, the fission product yield distribution and the total release energy, effect of inverse process cross section, mass distribution of fission product, calculation results of Cm isotope and systemicity of fission spectra of actinide isotope were investigated. (G.K.)

  5. Influence of fission modes on prompt neutron characteristics in the neutron-induced fission of 235U

    International Nuclear Information System (INIS)

    The de-excitation of the fission fragments formed in the neutron-induced fission of 235U, for incident energies from 0.5 to 6.0 MeV, is simulated numerically. Neutrons are emitted sequentially from a Weisskopf spectrum with a temperature set by previous neutron emissions. The complete decay chain is followed until a fission product is formed and no further neutron emission is allowed energetically. Detailed results are obtained, such as the average prompt neutron multiplicity as a function of the fragment mass and the total kinetic energy ν(A,TKE) and the multiplicity distribution P(ν). An interpretation in terms of fission modes is proposed. It appears that numerical modeling tools have to be sharpened. The results presented here are very promising and should be improved. The proper Hauser-Feshbach treatment (as opposed to Weisskopf-Ewing) of the evaporation process of the excited fission fragments has to be implemented, in particular to correctly account for the competition between neutron and gamma emission near the neutron binding energy

  6. Investigating Prompt Fission Neutron Emission from 235U(n,f) in the Resolved Resonance Region

    Science.gov (United States)

    Göök, Alf; Hambsch, Franz-Josef; Oberstedt, Stephan

    2016-03-01

    Investigations of prompt emission in fission is of importance in understanding the fission process in general and the sharing of excitation energy among the fission fragments in particular. Experimental activities at IRMM on prompt neutron emission from fission in response to OECD/NEA nuclear data requests is presented in this contribution. Main focus lies on currently on-going investigations of prompt neutron emission from the reaction 235U(n,f) in the region of the resolved resonances. For this reaction strong fluctuations of fission fragment mass distributions and mean total kinetic energy have been observed [Nucl. Phys. A 491, 56 (1989)] as a function of incident neutron energy in the resonance region. In addition fluctuations of prompt neutron multiplicities were also observed [Phys. Rev. C 13, 195 (1976)]. The goal of the present study is to verify the current knowledge of prompt neutron multiplicity fluctuations and to study correlations with fission fragment properties.

  7. Investigating Prompt Fission Neutron Emission from 235U(n,f in the Resolved Resonance Region

    Directory of Open Access Journals (Sweden)

    Göök Alf

    2016-01-01

    Full Text Available Investigations of prompt emission in fission is of importance in understanding the fission process in general and the sharing of excitation energy among the fission fragments in particular. Experimental activities at IRMM on prompt neutron emission from fission in response to OECD/NEA nuclear data requests is presented in this contribution. Main focus lies on currently on-going investigations of prompt neutron emission from the reaction 235U(n,f in the region of the resolved resonances. For this reaction strong fluctuations of fission fragment mass distributions and mean total kinetic energy have been observed [Nucl. Phys. A 491, 56 (1989] as a function of incident neutron energy in the resonance region. In addition fluctuations of prompt neutron multiplicities were also observed [Phys. Rev. C 13, 195 (1976]. The goal of the present study is to verify the current knowledge of prompt neutron multiplicity fluctuations and to study correlations with fission fragment properties.

  8. Summary Report of Second Research Coordination Meeting on Prompt Fission Neutron Spectra of Major Actinides

    International Nuclear Information System (INIS)

    A summary is given of the Second Research Coordination Meeting on Prompt Fission Neutron Spectra of Actinides. Experimental data and modelling methods on prompt fission neutron spectra were reviewed. Extensive technical discussions held on theoretical methods to calculate prompt fission spectra. Detailed coordinated research proposals have been agreed. Summary reports of selected technical presentations at the meeting are given. The resulting work plan of the Coordinated Research Programme is summarized, along with actions and deadlines. (author)

  9. Direct measurement of prompt neutrons emitted in fission of 226Ra by 12 MeV protons

    International Nuclear Information System (INIS)

    Prompt neutron energy distributions were measured at 0 deg and 90 deg with respect to the fission axis, in correlation with the mass-energy distribution of the fragments, for the fission of 226Ra induced by 12 MeV protons. The average number and average kinetic energy of prefission and postfission neutrons were obtained as a function of fragment mass and total kinetic energy. The average number of prefission neutrons emitted is 0.33+-0.15 n/fission (this includes also contributions from scission neutrons). By comparing this result with calculations of the average number of 'true' prefission neutrons, it was found that the number of 'true' prefission neutrons is zero. The average number of postfission neutrons emitted from both fragments is 3,20+-0.20 with an average kinetic energy of 1.33+-0.07 MeV. The dependence of the number of postfission neutrons on the fragment mass can be interpreted as a combination of a saw-tooth structure for the asymmetric mass division and a linearly increasing function for the symmetric mass division. (author)

  10. Neutron imaging and prompt gamma activation analysis using a monolithic capillary neutron lens

    International Nuclear Information System (INIS)

    Neutron focusing lenses have been shown to enhance the measurement capabilities of prompt gamma activation analysis (PGAA) for small samples (∼100 μm in size) using a reactor-based cold neutron beam. As reported in our earlier work, a cold neutron beam emerging from a 58Ni-coated guide, cross section 50 mm x 45 mm, is compressed to a spot size of about 0.54 mm (FWHM). In the current work, we report preliminary prompt gamma measurements performed with a monolithic capillary lens that accepts a 10 mm (hexagon flat-to-flat) size beam and focuses it to a spot size of 40. The smaller focal spot size enables better spatial resolution, but also makes sample alignment more challenging. We have added a neutron imaging technique to the sample positioning procedure that takes advantage of the converging and subsequent diverging nature of the focused beam. The measurement sensitivity for a 2.6 μg Gd sample has improved by a factor of 34. In addition to rastering samples in the lateral plane, we have also explored the possibility of profiling the inhomogeneity of the sample in the direction along the beam axis. (author)

  11. Summary Report of First Research Coordination Meeting on Prompt Fission Neutron Spectra of Major Actinides

    International Nuclear Information System (INIS)

    A summary is given of the First Research Coordination Meeting on Prompt Fission Neutron Spectra of Actinides. Experimental data and modelling methods on prompt fission neutron spectra were reviewed. The programme to compile and evaluate prompt fission spectra including uncertainty information over the neutron energy range from thermal to 20 MeV was proposed. Validation of the resulting data against integral critical assembly and dosimetry data is foreseen. Detailed coordinated research proposals have been agreed. Summary reports of technical presentations at the meeting are given. The resulting work plan of the Coordinated Research Programme is summarized, along with actions and deadlines. (author)

  12. Prompt gamma and neutron detection in BNCT utilizing a CdTe detector.

    Science.gov (United States)

    Winkler, Alexander; Koivunoro, Hanna; Reijonen, Vappu; Auterinen, Iiro; Savolainen, Sauli

    2015-12-01

    In this work, a novel sensor technology based on CdTe detectors was tested for prompt gamma and neutron detection using boronated targets in (epi)thermal neutron beam at FiR1 research reactor in Espoo, Finland. Dedicated neutron filter structures were omitted to enable simultaneous measurement of both gamma and neutron radiation at low reactor power (2.5 kW). Spectra were collected and analyzed in four different setups in order to study the feasibility of the detector to measure 478 keV prompt gamma photons released from the neutron capture reaction of boron-10. The detector proved to have the required sensitivity to detect and separate the signals from both boron neutron and cadmium neutron capture reactions, which makes it a promising candidate for monitoring the spatial and temporal development of in vivo boron distribution in boron neutron capture therapy. PMID:26249745

  13. Extraction of polychromatic thermal neutrons by Bragg diffraction to use for prompt gamma neutron activation analysis

    International Nuclear Information System (INIS)

    Extraction method of thermal neutron beam by Bragg diffraction is investigated. A thermal neutron beam is used for the Prompt Gamma Neutron Activation Analysis system at HANARO, a 30 MW research reactor in the Korea Atomic Energy Research Institute. Polychromatic beam including all orders of diffraction is obtained by setting a pair of pyrolytic graphite crystals with a Bragg angle of 45 deg. on a horizontal white beam line. Diffracted neutron flux at the sample position is calculated by considering the integrated reflectivity and mosaic spread of crystals. Due to the divergence effect, the mosaic spread of crystals is optimized to give the maximum and flat flux at the sample position. An experiment has been performed to verify the reflectivities for high order diffractions from pyrolytic graphite. When the focusing technique of bending the crystals is adopted, a design value of 1.0x108 n/cm2s is expected at the sample position. Hence Bragg diffraction is a promising method of extracting thermal neutrons for PGNAA

  14. The comparison of four neutron sources for Prompt Gamma Neutron Activation Analysis (PGNAA) in vivo detections of boron

    OpenAIRE

    Fantidis, J. G.; Nicolaou, G. E.; C. Potolias; N. Vordos; Bandekas, D. V.

    2011-01-01

    A Prompt Gamma Ray Neutron Activation Analysis (PGNAA) system, incorporating an isotopic neutron source has been simulated using the MCNPX Monte Carlo code. In order to improve the signal to noise ratio different collimators and a filter were placed between the neutron source and the object. The effect of the positioning of the neutron beam and the detector relative to the object has been studied. In this work the optimisation procedure is demonstrated for boron. Monte Carlo calculations were...

  15. Prompt neutron spectrum of the spontaneous fission of californium-252

    International Nuclear Information System (INIS)

    The californium-252 spontaneous fission neutron spectrum was measured in the energy range of 0.01 to 10 MeV by the time-of-flight technique using various neutron detectors. The measurements of 252Cf neutron spectrum at energies of 0.01 to 5 MeV were performed as a function of fission fragment kinetic energy. The mean neutron spectrum energy in the range of 0.7 to 10 MeV was found from the results of measurements. The irregularity in the 252Cf neutron spectrum in the neutron energy range of less than 0.7 MeV compared to theoretical values is discussed. The mechanism of 252Cf neutron emission is also discussed on the basis of neutron yield angle measurements. 12 references

  16. Prompt Gamma-Ray Neutron Activation Analysis (PGNAA) for Elemental Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Robin P. Gardner

    2006-04-11

    This research project was to improve the prompt gamma-ray neutron activation analysis (PGNAA) measurement approach for bulk analysis, oil well logging, and small sample thermal enutron bean applications.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-10-15

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

  18. Calculation of Prompt Fission Neutron Spectra for ~(235)U (n,f)

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The prompt fission neutron spectra for neutron-induced fission of 235U at En<5 MeV are calculated using the nuclear evaporation theory with a semi-empirical model, in which the non-constant temperature and the constant temperature related to the Fermi gas model

  19. Remark on the prompt-fission-neutron spectrum of 252Cf

    International Nuclear Information System (INIS)

    Good resolution time-of-flight measurements show small structure in the prompt fission neutron spectrum of 252Cf that is identified with air-scattering effects. The observed high energy portion of the neutron spectrum is consistent with a Maxwellian distribution having a temperature of 1.42 MeV

  20. Isotope identification capabilities using time resolved prompt gamma emission from epithermal neutrons

    International Nuclear Information System (INIS)

    We present a concept of integrated measurements for isotope identification which takes advantage of the time structure of spallation neutron sources for time resolved γ spectroscopy. Time resolved Prompt Gamma Activation Analysis (T-PGAA) consists in the measurement of gamma energy spectrum induced by the radioactive capture as a function of incident neutron Time Of Flight (TOF), directly related with the energy of incident neutrons. The potential of the proposed concept was explored on INES (Italian Neutron Experimental Station) at the ISIS spallation neutron source (U.K.). Through this new technique we show an increase in the sensitivity to specific elements of archaeometric relevance, through incident neutron energy selection in prompt γ spectra for multicomponent samples. Results on a standard bronze sample are presented

  1. Monte Carlo Calculation for Landmine Detection using Prompt Gamma Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seungil; Kim, Seong Bong; Yoo, Suk Jae [Plasma Technology Research Center, Gunsan (Korea, Republic of); Shin, Sung Gyun; Cho, Moohyun [POSTECH, Pohang (Korea, Republic of); Han, Seunghoon; Lim, Byeongok [Samsung Thales, Yongin (Korea, Republic of)

    2014-05-15

    Identification and demining of landmines are a very important issue for the safety of the people and the economic development. To solve the issue, several methods have been proposed in the past. In Korea, National Fusion Research Institute (NFRI) is developing a landmine detector using prompt gamma neutron activation analysis (PGNAA) as a part of the complex sensor-based landmine detection system. In this paper, the Monte Carlo calculation results for this system are presented. Monte Carlo calculation was carried out for the design of the landmine detector using PGNAA. To consider the soil effect, average soil composition is analyzed and applied to the calculation. This results has been used to determine the specification of the landmine detector.

  2. Evaluation of secondary and prompt fission neutron spectra

    Energy Technology Data Exchange (ETDEWEB)

    Porodzinskij, Yu.V.; Sukhovitskij, E.Sh. [Radiation Physics and Chemistry Problems Inst., Minsk-Sosny (Belarus)

    1997-03-01

    A simple model allowing to split neutron emission spectra into reaction partials is suggested. Predicted spectra of (n,n`{gamma}), (n,n`f), etc appear to be much harder than usually evaluated. (author)

  3. The statistical model calculation of prompt neutron spectra from spontaneous fission of {sup 244}Cm and {sup 246}Cm

    Energy Technology Data Exchange (ETDEWEB)

    Gerasimenko, B.F. [V.G. Khlopin Radium Inst., Saint Peterburg (Russian Federation)

    1997-03-01

    The calculations of integral spectra of prompt neutrons of spontaneous fission of {sup 244}Cm and {sup 246}Cm were carried out. The calculations were done by the Statistical Computer Code Complex SCOFIN applying the Hauser-Feschbach method as applied to the description of the de-excitation of excited fission fragments by means of neutron emission. The emission of dipole gamma-quanta from these fragments was considered as a competing process. The average excitation energy of a fragment was calculated by two-spheroidal model of tangent fragments. The density of levels in an excited fragment was calculated by the Fermi-gas model. The quite satisfactory agreement was reached between theoretical and experimental results obtained in frames of Project measurements. The calculated values of average multiplicities of neutron number were 2,746 for {sup 244}Cm and 2,927 for {sup 246}Cm that was in a good accordance with published experimental figures. (author)

  4. Characterization of hydrogen in concrete by cold neutron prompt gamma-ray activation analysis and neutron incoherent scattering

    Energy Technology Data Exchange (ETDEWEB)

    Paul, R.L.; Chen-Mayer, H.H.; Lindstrom, R.M.; Blaauw, M.

    2000-07-01

    A combination of cold neutron prompt gamma-ray activation analysis (PGAA) and neutron incoherent scattering (NIS) has been used for nondestructive characterization of hydrogen as a function of position in slabs of wet concrete of different composition. Hydrogen was determined by PGAA by scanning each sample across of 5 mm diameter neutron beam in 10 mm increments, and measuring the 2223 keV prompt gamma ray. NIS measurements were performed by scanning the samples across a 5 mm diameter neutron beam at 5 mm increments and detecting scattered neutrons. The measurements demonstrate the feasibility of the techniques for 2D compositional mapping of hydrogen and other elements in materials, and indicate the potential of these methods for monitoring the uniformity of drying concrete.

  5. Utilization of recycled neutron source to teach prompt gamma analysis activation-PGNA

    Science.gov (United States)

    Delgado-Correal, Camilo; Munera, Hector

    2008-03-01

    Neutron activation analysis based on prompt gamma ray emission has significantly developed during the past twenty years. The technique is particularly suited for the identification of low atomic number elements, as nitrogen that is a main component of drugs and explosives. Identification of these substances is important in the context of humanitarian demining, and in the control of illicit traffic of drugs and explosives. As a good example of recycling of radioactive sources, a ^241Am-Be neutron source emitting 10^7neutron/s, that was not longer in use for other purposes at Ingeominas, was used to build a neutron irradiator that can be used to teach prompt gamma ray analysis, and other nuclear techniques. We irradiated individual samples, each about 4 gram, of three different elements: nitrogen in urea, silicon in milled rock, and cadmium in cadmium oxide. The prompt gamma rays emitted in the nuclear reactions ^112Cd (neutron,gamma) ^113Cd, ^28Si (neutron,gamma) ^29Si and ^14N (neutron,gamma) ^15N were identified using a well-type NaI (Tl) detector, connected to a multi-channel analyzer.

  6. The comparison of four neutron sources for Prompt Gamma Neutron Activation Analysis (PGNAA) in vivo detections of boron

    International Nuclear Information System (INIS)

    A Prompt Gamma Ray Neutron Activation Analysis (PGNAA) system, incorporating an isotopic neutron source has been simulated using the MCNPX Monte Carlo code. In order to improve the signal to noise ratio different collimators and a filter were placed between the neutron source and the object. The effect of the positioning of the neutron beam and the detector relative to the object has been studied. In this work the optimisation procedure is demonstrated for boron. Monte Carlo calculations were carried out to compare the performance of the proposed PGNAA system using four different neutron sources (241Am/Be, 252Cf, 241Am/B, and DT neutron generator). Among the different systems the 252Cf neutron based PGNAA system has the best performance. (author)

  7. Stability evaluation and correction of a pulsed neutron generator prompt gamma activation analysis system

    International Nuclear Information System (INIS)

    Source output stability is important for accurate measurement in prompt gamma neutron activation. This is especially true when measuring low-concentration elements such as in vivo nitrogen (∼2.5 % of body weight). We evaluated the stability of the compact DT neutron generator within an in vivo nitrogen measurement system. Review of gamma event/time patterns and data from an auxiliary detector showed significant variations among repeated phantom runs. Neutron generator instability had a significant effect on measurement precision. The neutron generator used in our system must be monitored for output consistency. Adjustments must be made to measurement results to correct for generator instability. (author)

  8. The LICORNE Neutron Source and Measurements of Prompt γ-rays Emitted in Fission

    Science.gov (United States)

    Wilson, J. N.; Lebois, M.; Halipre, P.; Oberstedt, S.; Oberstedt, A.

    The emission of prompt gamma rays is one of the least measured and least well-understood parts of the fission process. Knowledge of prompt fission gamma spectra, mean energies and multiplicities are important for reactor gamma heating and hence linked to reactor safety. At the IPN Orsay we have developed a unique, directional, fast neutron source called LICORNE, intended initially to facilitate prompt fission gamma measurements. The ability of the IPN Orsay tandem accelerator to produce intense beams of 7Li is exploited to produce quasi mono-energetic neutrons between 0.5 - 4 MeV using the p(7Li, 7Be)n inverse reaction. The available fluxes of up to 7×107 neutrons/second/steradian are comparable to existing installations, but with two added advantages: (i) The kinematic focusing produces a natural neutron beam collimation which allows placement of gamma detectors adjacent to the irradiated sample unimpeded by source neutrons. (ii) The background of scattered neutrons in the experimental hall is drastically reduced. The dedicated neutron converter was commissioned in June 2013

  9. Average Soil Water Retention Curves Measured by Neutron Radiography

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Chu-Lin [ORNL; Perfect, Edmund [University of Tennessee, Knoxville (UTK); Kang, Misun [ORNL; Voisin, Sophie [ORNL; Bilheux, Hassina Z [ORNL; Horita, Juske [Texas Tech University (TTU); Hussey, Dan [NIST Center for Neutron Research (NCRN), Gaithersburg, MD

    2011-01-01

    Water retention curves are essential for understanding the hydrologic behavior of partially-saturated porous media and modeling flow transport processes within the vadose zone. In this paper we report direct measurements of the main drying and wetting branches of the average water retention function obtained using 2-dimensional neutron radiography. Flint sand columns were saturated with water and then drained under quasi-equilibrium conditions using a hanging water column setup. Digital images (2048 x 2048 pixels) of the transmitted flux of neutrons were acquired at each imposed matric potential (~10-15 matric potential values per experiment) at the NCNR BT-2 neutron imaging beam line. Volumetric water contents were calculated on a pixel by pixel basis using Beer-Lambert s law after taking into account beam hardening and geometric corrections. To remove scattering effects at high water contents the volumetric water contents were normalized (to give relative saturations) by dividing the drying and wetting sequences of images by the images obtained at saturation and satiation, respectively. The resulting pixel values were then averaged and combined with information on the imposed basal matric potentials to give average water retention curves. The average relative saturations obtained by neutron radiography showed an approximate one-to-one relationship with the average values measured volumetrically using the hanging water column setup. There were no significant differences (at p < 0.05) between the parameters of the van Genuchten equation fitted to the average neutron radiography data and those estimated from replicated hanging water column data. Our results indicate that neutron imaging is a very effective tool for quantifying the average water retention curve.

  10. Prompt gamma-ray neutron activation analysis of boron using Deuterium-Deuterium (D-D) neutron generator

    International Nuclear Information System (INIS)

    Prompt gamma-ray neutron activation analysis (PGNAA) is a nuclear analytical technique for the determination of trace and other elements in solid, liquid or gaseous samples. The method consists in observing gamma rays emitted by a sample during neutron irradiation. The PGNAA system was built using a moderated and shielded deuterium-deuterium (D-D) neutron generator. This facility has been developed to determine the chemical composition of materials. The neutron generator is composed of three major components: An RF-Induction Ion Source, the Secondary Electron Shroud, and the Diode Accelerator Structure and Target. The generator produces monoenergetic neutrons (2.5 MeV) with a yield of 1010 n/s using 25-50 mA of beam current and 125 kV of acceleration voltage. Prompt γ-ray neutron activation analysis of 10B concentrations in Si and SiO2 matrices was carried out using a germanium detector (HPGe) and the results obtained are compared with a PGNAA system using a NaI detector. Neutron flux and energy distribution from D-D neutron generator at the sample position was calculated using Monte Carlo simulation. The interaction properties of neutrons in a Germanium detector have been studied. (author)

  11. Measurements of prompt fission gamma-rays and neutrons with lanthanide halide scintillation detectors

    CERN Document Server

    Oberstedt, A; Billnert, R; Borcea, R; Brys, T; Chaves, C; Gamboni, T; Geerts, W; Göök, A; Guerrero, C; Hambsch, F-J; Kis, Z; Martinez, T; Oberstedt, S; Szentmiklosi, L; Takács, K; Vivaldi, M

    2014-01-01

    Photons have been measured with lanthanide halide scintillation detectors in coincidence with fission fragments. Using the time-of-flight information, reactions from γ-rays and neutrons could easily be distinguished. In several experiments on $^{252}$Cf(sf), $^{235}$U(n$_{th}$,f) and $^{241}$Pu(n$_{th}$,f) prompt fission γ-ray spectra characteristics were determined with high precision and the results are presented here. Moreover, a measured prompt fission neutron spectrum for $^{235}$U(n$_{th}$,f) is shown in order to demonstrate a new detection technique.

  12. A compact neutron beam generator system designed for prompt gamma nuclear activation analysis

    International Nuclear Information System (INIS)

    In this work a compact system was designed for bulk sample analysis using the technique of PGNAA. The system consists of 252Cf fission neutron source, a moderator/reflector/filter assembly, and a suitable enclosure to delimit the resulting neutron beam. The moderator/reflector/filter arrangement has been optimised to maximise the thermal neutron component useful for samples analysis with a suitably low level of beam contamination. The neutron beam delivered by this compact system is used to irradiate the sample and the prompt gamma rays produced by neutron reactions within the sample elements are detected by appropriate gamma rays detector. Neutron and gamma rays transport calculations have been performed using the Monte Carlo N-Particle transport code (MCNP5).

  13. A compact neutron beam generator system designed for prompt gamma nuclear activation analysis.

    Science.gov (United States)

    Ghassoun, J; Mostacci, D

    2011-08-01

    In this work a compact system was designed for bulk sample analysis using the technique of PGNAA. The system consists of (252)Cf fission neutron source, a moderator/reflector/filter assembly, and a suitable enclosure to delimit the resulting neutron beam. The moderator/reflector/filter arrangement has been optimised to maximise the thermal neutron component useful for samples analysis with a suitably low level of beam contamination. The neutron beam delivered by this compact system is used to irradiate the sample and the prompt gamma rays produced by neutron reactions within the sample elements are detected by appropriate gamma rays detector. Neutron and gamma rays transport calculations have been performed using the Monte Carlo N-Particle transport code (MCNP5). PMID:21129990

  14. A compact neutron beam generator system designed for prompt gamma nuclear activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ghassoun, J., E-mail: ghassoun@ucam.ac.ma [EPRA, Department of Physics, Faculty of Sciences, Semlalia, P.O. Box 2390, 40000 Marrakech (Morocco); Mostacci, D., E-mail: domiziano.mostacci@mail.ing.unibo.it [University of Bologna, Montecuccolino Laboratory, via dei Colli 16, I-40136 Bologna (Italy)

    2011-08-15

    In this work a compact system was designed for bulk sample analysis using the technique of PGNAA. The system consists of {sup 252}Cf fission neutron source, a moderator/reflector/filter assembly, and a suitable enclosure to delimit the resulting neutron beam. The moderator/reflector/filter arrangement has been optimised to maximise the thermal neutron component useful for samples analysis with a suitably low level of beam contamination. The neutron beam delivered by this compact system is used to irradiate the sample and the prompt gamma rays produced by neutron reactions within the sample elements are detected by appropriate gamma rays detector. Neutron and gamma rays transport calculations have been performed using the Monte Carlo N-Particle transport code (MCNP5).

  15. Measurements of prompt gamma-rays from fast-neutron induced fission with the LICORNE directional neutron source

    CERN Document Server

    Wilson, J N; Halipre, P; Oberstedt, S; Oberstedt, A

    2014-01-01

    At the IPN Orsay we have developed a unique, directional, fast neutron source called LICORNE, intended initially to facilitate prompt fission gamma measurements. The ability of the IPN Orsay tandem accelerator to produce intense beams of $^7$Li is exploited to produce quasi-monoenergetic neutrons between 0.5 - 4 MeV using the p($^7$Li,$^7$Be)n inverse reaction. The available fluxes of up to 7 × 10$^7$ neutrons/second/steradian for the thickest hydrogen-rich targets are comparable to similar installations, but with two added advantages: (i) The kinematic focusing produces a natural neutron beam collimation which allows placement of gamma detectors adjacent to the irradiated sample unimpeded by source neutrons. (ii) The background of scattered neutrons in the experimental hall is drastically reduced. The dedicated neutron converter was commissioned in June 2013. Some preliminary results from the first experiment using the LICORNE neutron source at the IPN Orsay are presented. Prompt fission gamma rays from fas...

  16. Two non-destructive neutron inspection techniques: prompt gamma-ray activation analysis and cold neutron tomography

    OpenAIRE

    Baechler, Sébastien; Dousse, Jean-Claude; Jolie, Jan

    2005-01-01

    Deux techniques d’inspection non-destructives utilisant des faisceaux de neutrons froids ont été développées à la source de neutrons SINQ de l’Institut Paul Scherrer : (1) l’analyse par activation neutronique prompte (PGAA) et (2) la tomographie neutronique. L’analyse par PGA (Prompt Gamma-ray Activation) est une méthode nucléaire qui permet de déterminer la concentration d’éléments présents dans un échantillon. Cette technique consiste à détecter les rayons gamma prompts émis par l’échantill...

  17. Progress of neutron induced prompt gamma analysis technique in 1988~2003

    Institute of Scientific and Technical Information of China (English)

    JING Shi-Wei; LIU Yu-Ren; CHI Yan-Tao; TIAN Yu-Bing; CAO Xi-Zheng; ZHAO Xin-Hui; REN Wan-Bin; LIU Lin-Mao

    2004-01-01

    This paper describes new development of the neutron induced prompt gamma-ray analysis (NIPGA) technology in 1988~2003. The pulse fast-thermal neutron activation analysis method, which utilized the inelastic re action and capture reaction jointly, was employed to measure the elemental contents more efficiently. Lifetime of the neutron generator was more than 10000h and the performance of detector and MCA reached a high level. At the same time, Monte Carlo library least-square method was used to solve the nonlinearity problem in the NIPGA.

  18. The measurement of prompt neutron spectrum in spontaneous fission of {sup 244}Cm

    Energy Technology Data Exchange (ETDEWEB)

    Batenkov, O.I.; Boykov, G.S.; Drapchinsky, L.V.; Majorov, M.Ju.; Trenkin, V.A. [V.G. Khlopin Radium Inst., Saint Petersburg (Russian Federation)

    1997-03-01

    Under the Program of Measurements of Prompt Fission Neutron Spectra of Minor Actinides for Transmutation Purposes the integral neutron spectrum in spontaneous fission of {sup 244}Cm has been measured by the time-of-flight method in the energy range of 0.1-15 MeV relative to the standard neutron spectrum in {sup 252}Cf spontaneous fission. Essential attention was paid to revealing of possible systematic errors. It is shown, that the {sup 244}Cm spectrum shape may be well described by using Mannhart evaluation with appropriate parameter of Maxwell temperature T{sub M} = 1.37 MeV. (author)

  19. Using anisotropies in prompt fission neutron coincidences to assess the neutron multiplication of highly multiplying subcritical plutonium assemblies

    Science.gov (United States)

    Mueller, J. M.; Mattingly, J.

    2016-07-01

    There is a significant and well-known anisotropy between the prompt neutrons emitted from a single fission event; these neutrons are most likely to be observed at angles near 0° or 180° relative to each other. However, the propagation of this anisotropy through different generations of a fission chain reaction has not been previously studied. We have measured this anisotropy in neutron-neutron coincidences from a subcritical highly-multiplying assembly of plutonium metal. The assembly was a 4.5 kg α-phase plutonium metal sphere composed of 94% 239Pu and 6% 240Pu by mass. Data were collected using two EJ-309 liquid scintillators and two EJ-299 plastic scintillators. The angular distribution of neutron-neutron coincidences was measured at 90° and 180° and found to be largely isotropic. Simulations were performed using MCNPX-PoliMi of similar plutonium metal spheres of varying sizes and a correlation between the neutron multiplication of the assembly and the anisotropy of neutron-neutron coincidences was observed. In principle, this correlation could be used to assess the neutron multiplication of an unknown assembly.

  20. Experimental study of prompt neutron decay constant α for 300# pool reactor under mixed core

    International Nuclear Information System (INIS)

    The experimental study of prompt neutron decay constant α for 300# pool reactor under mixed core was carried out through a suit of reactor power spectral density measurement system. The two channel continuous current signals of neutron in the reactor were acquired by ionization chamber DL129 which was symmetrically putted in reactor core. The power spectral density, for two channel signals, was computed using the application program of data acquirement and data process analysis. Finally, by using the non-linear least squares method, the prompt neutron decay constant α was fitted. By comparison, the experimental results well accord to the theory calculation within the error range. The deviation can meet the actual need of project. (authors)

  1. Development of Monte Carlo code for coincidence prompt gamma-ray neutron activation analysis

    Science.gov (United States)

    Han, Xiaogang

    Prompt Gamma-Ray Neutron Activation Analysis (PGNAA) offers a non-destructive, relatively rapid on-line method for determination of elemental composition of bulk and other samples. However, PGNAA has an inherently large background. These backgrounds are primarily due to the presence of the neutron excitation source. It also includes neutron activation of the detector and the prompt gamma rays from the structure materials of PGNAA devices. These large backgrounds limit the sensitivity and accuracy of PGNAA. Since most of the prompt gamma rays from the same element are emitted in coincidence, a possible approach for further improvement is to change the traditional PGNAA measurement technique and introduce the gamma-gamma coincidence technique. It is well known that the coincidence techniques can eliminate most of the interference backgrounds and improve the signal-to-noise ratio. A new Monte Carlo code, CEARCPG has been developed at CEAR to simulate gamma-gamma coincidence spectra in PGNAA experiment. Compared to the other existing Monte Carlo code CEARPGA I and CEARPGA II, a new algorithm of sampling the prompt gamma rays produced from neutron capture reaction and neutron inelastic scattering reaction, is developed in this work. All the prompt gamma rays are taken into account by using this new algorithm. Before this work, the commonly used method is to interpolate the prompt gamma rays from the pre-calculated gamma-ray table. This technique works fine for the single spectrum. However it limits the capability to simulate the coincidence spectrum. The new algorithm samples the prompt gamma rays from the nucleus excitation scheme. The primary nuclear data library used to sample the prompt gamma rays comes from ENSDF library. Three cases are simulated and the simulated results are benchmarked with experiments. The first case is the prototype for ETI PGNAA application. This case is designed to check the capability of CEARCPG for single spectrum simulation. The second

  2. Beam characteristics of polychromatic diffracted neutrons used for prompt gamma activation analysis

    International Nuclear Information System (INIS)

    The neutron beam is fully characterized for the prompt gamma activation analysis facility at Hanaro in the Korea Atomic Energy Research Institute(KAERI). The facility uses thermal neutrons which are diffracted vertically from a horizontal beam port by a set of pyrolytic graphite(PG) crystals positioned at the Bragg angle of 45 .deg.. Neutron spectra, neutron flux and Cd-ratio are determined for the three extraction modes of diffracted beam by means of the theoretical and experimental efforts. To obtain theoretical result, the reflectivity of pyrolytic graphite is calculated in the diffraction model for mosaic crystal and the angular divergence after diffraction by mosaic crystal is estimated from Monte Carlo simulation. The time-of-flight spectrometer and gold activation wire are used for measuring the neutron spectra. Both the calculated and measured spectra have proven that the unique feature of polychromatic beam obtained by PG crystals are useful for PGAA. The thermal neutron flux of 7.9 x 107 n/cm2s and the Cd-ratio of 266 for gold have been achieved at the sample position while the reactor operates at 24MW. The uniformity of beam flux is 12% in the central 1 x 1 cm2 area. Finally, the beam is briefly characterized by the effective velocity and temperature which are determined by measuring the prompt γ-ray spectra for thin and thick boron samples

  3. The Shapiro Conjecture Prompt or Delayed Collapse in the head-on collision of neutron stars?

    CERN Document Server

    Miller, M; Tobias, M; Miller, Mark; Suen, Wai-Mo; Tobias, Malcolm

    1999-01-01

    We study the question of prompt vs. delayed collapse in the head-on collision of two neutron stars. We show that the prompt formation of a black hole is possible, contrary to a conjecture of Shapiro which claims that collapse is delayed until after neutrino cooling. We discuss the insight provided by Shapiro's conjecture and its limitation. An understanding of the limitation of the conjecture is provided in terms of the many time scales involved in the problem. General relativistic simulations in the Einstein theory with the full set of Einstein equations coupled to the general relativistic hydrodynamic equations are carried out in our study.

  4. Prompt γ-ray spectroscopy of the neutron-rich 124Cd

    Directory of Open Access Journals (Sweden)

    Vancraeyenest A.

    2013-12-01

    Full Text Available Prompt γ-ray spectroscopy of neutron-rich cadmium isotopes has been performed. The nuclei of interest have been populated via a 25-MeV, proton-induced fission of the 238U thick target and prompt γ-rays measured using the multi-detector HPGe array JUROGAM II. New high-spin decays have been observed and placed in the level scheme using triple coincidence gates. The experimental results are compared to shell-model calculations and show good agreement.

  5. Resonance averaged channel radiative neutron capture cross sections

    International Nuclear Information System (INIS)

    In order to apply Lane amd Lynn's channel capture model in calculations with a realistic optical model potential, we have derived an approximate wave function for the entrance channel in the neutron-nucleus reaction, based on the intermediate interaction model. It is valid in the exterior region as well as the region near the nuclear surface, ans is expressed in terms of the wave function and reactance matrix of the optical model and of the near-resonance parameters. With this formalism the averaged channel radiative neutron capture cross section in the resonance region is written as the sum of three terms. The first two terms correspond to contribution of the optical model real and imaginary parts respectively, and together can be regarded as the radiative capture of the shape elastic wave. The third term is a fluctuation term, corresponding to the radiative capture of the compound elastic wave in the exterior region. On applying this theory in the resonance region, we obtain an expression for the average valence radiative width similar to that of Lane and Mughabghab. We have investigated the magnitude and energy dependence of the three terms as a function of the neutron incident energy. Calculated results for 98Mo and 55Mn show that the averaged channel radiative capture cross section in the giant resonance region of the neutron strength function may account for a considerable fraction of the total (n, γ) cross section; at lower neutron energies a large part of this channel capture arises from the fluctuation term. We have also calculated the partial capture cross section in 98Mo and 55Mn at 2.4 keV and 24 keV, respectively, and compared the 98Mo results with the experimental data. (orig.)

  6. Calculation of Prompt Fission Neutron from 233U(n, f) Reaction by Multi-Modal Los Alamos Model%Calculation of Prompt Fission Neutron from 233U(n, f) Reaction by Multi-Modal Los Alamos Model

    Institute of Scientific and Technical Information of China (English)

    郑娜; 钟春来; 樊铁栓

    2012-01-01

    An attempt is made to improve the evaluation of the prompt fission neutron emis- sion from 233U(n, f) reaction for incident neutron energies below 6 MeV. The multi-modal fission approach is applied to the improved version of Los Alamos model and the point by point model. The prompt fission neutron spectra and the prompt fission neutron as a function of fragment mass (usually named "sawtooth" data) v(A) are calculated independently for the three most dominant fission modes (standard I, standard II and superlong), and the total spectra and v(A) are syn- thesized. The multi-modal parameters are determined on the basis of experimental data of fission fragment mass distributions. The present calculation results can describe the experimental data very well, and the proposed treatment is thus a useful tool for prompt fission neutron emission prediction.

  7. Evaluating the 239Pu Prompt Fission Neutron Spectrum Induced by Thermal to 30 MeV Neutrons

    Science.gov (United States)

    Neudecker, D.; Talou, P.; Kawano, T.; Kahler, A. C.; Rising, M. E.; White, M. C.

    2016-03-01

    We present a new evaluation of the 239Pu prompt fission neutron spectrum (PFNS) induced by thermal to 30 MeV neutrons. Compared to the ENDF/B-VII.1 evaluation, this one includes recently published experimental data as well as an improved and extended model description to predict PFNS. For instance, the pre-equilibrium neutron emission component to the PFNS is considered and the incident energy dependence of model parameters is parametrized more realistically. Experimental and model parameter uncertainties and covariances are estimated in detail. Also, evaluated covariances are provided between all PFNS at different incident neutron energies. Selected evaluation results and first benchmark calculations using this evaluation are briefly discussed.

  8. Evaluating the 239Pu Prompt Fission Neutron Spectrum Induced by Thermal to 30 MeV Neutrons

    Directory of Open Access Journals (Sweden)

    Neudecker D.

    2016-01-01

    Full Text Available We present a new evaluation of the 239Pu prompt fission neutron spectrum (PFNS induced by thermal to 30 MeV neutrons. Compared to the ENDF/B-VII.1 evaluation, this one includes recently published experimental data as well as an improved and extended model description to predict PFNS. For instance, the pre-equilibrium neutron emission component to the PFNS is considered and the incident energy dependence of model parameters is parametrized more realistically. Experimental and model parameter uncertainties and covariances are estimated in detail. Also, evaluated covariances are provided between all PFNS at different incident neutron energies. Selected evaluation results and first benchmark calculations using this evaluation are briefly discussed.

  9. Gamma and Neutron Flux of a Prompt Gamma Neutron Activation Analysis Collimator at the PUSPATI TRIGA Reactor

    International Nuclear Information System (INIS)

    A Prompt Gamma Neutron Activation Analysis (PGNAA) facility is being studied for installation at PUSPATI TRIGA Reactor (RTP) under the Thorium Flagship programme. This work presents the preliminary design of a PGNAA collimator at the RTP. The result of calculations for gamma and neutron flux at various positions of the PGNAA collimator in the RTP beam port 1 by using the computer code MCNPX are presented and discussed. The results indicate the technical feasibility of the installation of PGNAA facility at the RTP and the possibility of enhancing the utilization of the RTP. (author)

  10. Determination of hydrogen in niobium by cold neutron prompt gamma ray activation analysis and neutron incoherent scattering

    Energy Technology Data Exchange (ETDEWEB)

    R.L. Paul; H.H. Cheu-Maya; G.R. Myneni

    2002-11-01

    The presence of trace amounts of hydrogen in niobium is believed to have a detrimental effect on the mechanical and superconducting properties. Unfortunately, few techniques are capable of measuring hydrogen at these levels. We have developed two techniques for measuring hydrogen in materials. Cold neutron prompt gamma-ray activation analysis (PGAA) has proven useful for the determination of hydrogen and other elements in a wide variety of materials. Neutron incoherent scattering (NIS), a complementary tool to PGAA, has been used to measure trace hydrogen in titanium. Both techniques were used to study the effects of vacuum heating and chemical polishing on the hydrogen content of superconducting niobium.

  11. Prompt gamma-ray detectors for the measurement of neutron capture cross-sections

    International Nuclear Information System (INIS)

    A review is given of current techniques for detecting prompt gamma-radiation as a means of measuring total capture cross-sections. The discussion is generally restricted to systems with low or moderate gamma-ray energy resolution. Three classes of detector are considered: (1) the total absorption type; (2) detectors with efficiency proportional to gamma-ray energy; and (3) detectors of low efficiency and known gamma-ray response. Particular attention is given to the problems of background from reactions which compete with neutron capture, and the sensitivity of capture detectors to scattered neutrons. The extraction of capture yields from observed data is briefly considered

  12. GPU-based prompt gamma ray imaging from boron neutron capture therapy

    International Nuclear Information System (INIS)

    This reaction can be applied to the therapy and diagnosis about the tumor simultaneously. After the compound labeled with the boron is accumulated at the tumor site, the alpha particle induced by the reaction between the thermal neutron and the boron induces tumor cell death. Also, the 478 keV prompt gamma ray is emitted from the same reaction point. If this single prompt photon is detected by single photon emission computed tomography (SPECT), the tomographic image of the therapy region can be monitored during the radiation treatment. However, in order to confirm the therapy region using the image during the treatment, the image needs to be provided promptly. Due to a relatively long acquisition time required to get SPECT images, both reduced number of projections and the fast image reconstruction schemes are needed to provide the images during radiation treatment. The computation time for image reconstruction using the GPU with the modified OSEM algorithm was measured and compared with the computation time using CPU. Through the results, we confirmed the feasibility of the image reconstruction for prompt gamma ray image using GPU for the BNCT. In the further study, the development of the algorithm for faster reconstruction of the prompt gamma ray image during the BNCT using the GPU computation will be conducted. Also, the analysis of the target to background level about the reconstructed image will be performed using the extracted image profile

  13. GPU-based prompt gamma ray imaging from boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Do-Kun; Jung, Joo-Young; Suh, Tae Suk [College of Medicine, Catholic University of Korea, Seoul (Korea, Republic of)

    2015-05-15

    This reaction can be applied to the therapy and diagnosis about the tumor simultaneously. After the compound labeled with the boron is accumulated at the tumor site, the alpha particle induced by the reaction between the thermal neutron and the boron induces tumor cell death. Also, the 478 keV prompt gamma ray is emitted from the same reaction point. If this single prompt photon is detected by single photon emission computed tomography (SPECT), the tomographic image of the therapy region can be monitored during the radiation treatment. However, in order to confirm the therapy region using the image during the treatment, the image needs to be provided promptly. Due to a relatively long acquisition time required to get SPECT images, both reduced number of projections and the fast image reconstruction schemes are needed to provide the images during radiation treatment. The computation time for image reconstruction using the GPU with the modified OSEM algorithm was measured and compared with the computation time using CPU. Through the results, we confirmed the feasibility of the image reconstruction for prompt gamma ray image using GPU for the BNCT. In the further study, the development of the algorithm for faster reconstruction of the prompt gamma ray image during the BNCT using the GPU computation will be conducted. Also, the analysis of the target to background level about the reconstructed image will be performed using the extracted image profile.

  14. Development of a prompt gamma activation analysis facility using diffracted polychromatic neutron beam

    CERN Document Server

    Byun, S H; Choi, H D

    2002-01-01

    A prompt gamma activation analysis facility has recently been developed at Hanaro, the 24 MW research reactor in the Korea Atomic Energy Research Institute. Polychromatic thermal neutrons are extracted by setting pyrolytic graphite crystals at a Bragg angle of 45 deg. . The detection system comprises a large single n-type HPGe detector, signal electronics and a fast ADC. Neutron beam characterization was performed both theoretically and experimentally. The neutron flux was measured to be 7.9x10 sup 7 n/cm sup 2 s in a 1x1 cm sup 2 beam area at the sample position with a uniformity of 12%. The corresponding Cd-ratio for gold was found to be 266. The beam quality was compared with other representative thermal neutron prompt gamma activation analysis. The detection efficiency was calibrated up to 11 MeV using a set of radionuclides and the (n,gamma) reactions of N and Cl. Finally, the sensitivities and the detection limits were obtained for several elements.

  15. Development of a prompt gamma activation analysis facility using diffracted polychromatic neutron beam

    International Nuclear Information System (INIS)

    A prompt gamma activation analysis facility has recently been developed at Hanaro, the 24 MW research reactor in the Korea Atomic Energy Research Institute. Polychromatic thermal neutrons are extracted by setting pyrolytic graphite crystals at a Bragg angle of 45 deg. . The detection system comprises a large single n-type HPGe detector, signal electronics and a fast ADC. Neutron beam characterization was performed both theoretically and experimentally. The neutron flux was measured to be 7.9x107 n/cm2 s in a 1x1 cm2 beam area at the sample position with a uniformity of 12%. The corresponding Cd-ratio for gold was found to be 266. The beam quality was compared with other representative thermal neutron prompt gamma activation analysis. The detection efficiency was calibrated up to 11 MeV using a set of radionuclides and the (n,γ) reactions of N and Cl. Finally, the sensitivities and the detection limits were obtained for several elements

  16. A position-sensitive twin ionization chamber for fission fragment and prompt neutron correlation experiments

    Science.gov (United States)

    Göök, A.; Geerts, W.; Hambsch, F.-J.; Oberstedt, S.; Vidali, M.; Zeynalov, Sh.

    2016-09-01

    A twin position-sensitive Frisch grid ionization chamber, intended as a fission fragment detector in experiments to study prompt fission neutron correlations with fission fragment properties, is presented. Fission fragment mass and energies are determined by means of the double kinetic energy technique, based on conservation of mass and linear momentum. The position sensitivity is achieved by replacing each anode plate in the standard twin ionization chamber by a wire plane and a strip anode, both readout by means of resistive charge division. This provides information about the fission axis orientation, which is necessary to reconstruct the neutron emission process in the fully accelerated fragment rest-frame. The energy resolution compared to the standard twin ionization chamber is found not to be affected by the modification. The angular resolution of the detector relative to an arbitrarily oriented axis is better than 7° FWHM. Results on prompt fission neutron angular distributions in 235U(n,f) obtained with the detector in combination with an array of neutron scintillation detectors is presented as a proof of principle.

  17. Transitions, cross sections and neutron binding energy in 186Re by Prompt Gamma Activation Analysis

    Science.gov (United States)

    Lerch, A. G.; Hurst, A. M.; Firestone, R. B.; Revay, Zs.; Szentmiklosi, L.; McHale, S. R.; McClory, J. W.; Detwiler, B.; Carroll, J. J.

    2014-03-01

    The nuclide 186Re possesses an isomer with 200,000 year half-life while its ground state has a half-life of 3.718 days. It is also odd-odd and well-deformed nucleus, so should exhibit a variety of other interesting nuclear-structure phenomena. However, the available nuclear data is rather sparse; for example, the energy of the isomer is only known to within + 7 keV and, with the exception of the J?=1- ground state, every proposed level is tentative in the ENSDF. Previously, Prompt Gamma Activation Analysis (PGAA) was utilized to study natRe with 186,188Re being produced via thermal neutron capture. Recently, an enriched 185Re target was irradiated by thermal neutrons at the Budapest Research Reactor to build on those results. Prompt (primary and secondary) and delayed gamma-ray transitions were measured with a large-volume, Compton-suppressed HPGe detector. Absolute cross sections for each gamma transition were deduced and corrected for self attenuation within the sample. Fifty-two primary gamma-ray transitions were newly identified and used to determine a revised value of the neutron binding energy. DICEBOX was used to simulate the decay scheme and the total radiative thermal neutron capture cross section was found to be 97+/-3 b Supported by DTRA (Detwiler) through HDTRA1-08-1-0014.

  18. Prompt γ-ray production in neutron-induced fission of 239Pu

    Science.gov (United States)

    Ullmann, J. L.; Bond, E. M.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Kawano, T.; Lee, H. Y.; O'Donnell, J. M.; Hayes, A. C.; Stetcu, I.; Taddeucci, T. N.; Talou, P.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Chyzh, A.; Gostic, J.; Henderson, R.; Kwan, E.; Wu, C. Y.

    2013-04-01

    Background: The prompt gamma-ray spectrum from fission is important for understanding the physics of nuclear fission, and also in applications involving fission. Relatively few measurements of the prompt gamma spectrum from 239Pu(n,f) have been published.Purpose: This experiment measured the multiplicity, individual gamma energy spectrum, and total gamma energy spectrum of prompt fission gamma rays from 239Pu(n,f) in the neutron energy range from thermal to 30 keV, to test models of fission and to provide information for applications.Method: Gamma rays from neutron-induced fission of 239Pu were measured using the DANCE gamma-ray calorimeter. Fission events were tagged by detecting fission products in a parallel-plate avalanche counter in the center of DANCE. The measurements were corrected for detector response using a geant4 model of DANCE. A detailed analysis for the gamma rays from the 1+ resonance complex at 10.93 eV is presented.Results: A six-parameter analytical parametrization of the fission gamma-ray spectrum was obtained. A Monte Carlo Hauser-Feshbach calculation provided good general agreement with the data, but some differences remain to be resolved.Conclusions: An analytic parametrization can be made of the gamma-ray multiplicity, energy distribution, and total-energy distribution for the prompt gamma rays following neutron-induced fission of 239Pu. This parametrization may be useful for applications. Modern Monte Carlo Hauser-Feshbach calculations can do a good job of calculating the fission gamma-ray emission spectrum, although some details remain to be understood.

  19. Event-by-event study of prompt neutrons from 239Pu(n,f)

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, R; Randrup, J; Pruet, J; Younes, W

    2009-07-23

    Employing a recently developed Monte-Carlo model, we study the fission of {sup 240}Pu induced by neutrons with energies from thermal to just below the threshold for second chance fission. Current measurements of the mean number of prompt neutrons emitted in fission, together with less accurate measurements of the neutron energy spectra, place remarkably fine constraints on predictions of microscopic calculations. In particular, the total excitation energy of the nascent fragments must be specified to within 1MeV to avoid disagreement with measurements of the mean neutron multiplicity. The combination of the Monte-Carlo fission model with a statistical likelihood analysis also presents a powerful tool for the evaluation of fission neutron data. Of particular importance is the fission spectrum, which plays a key role in determining reactor criticality. We show that our approach can be used to develop an estimate of the fission spectrum with uncertainties several times smaller than current experimental uncertainties for outgoing neutron energies of less than 2 MeV.

  20. Event-by-Event Study of Prompt Neutrons from 239Pu

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, R; Randrup, J; Pruet, J; Younes, W

    2010-01-15

    Employing a recently developed Monte Carlo model, we study the fission of {sup 240}Pu induced by neutrons with energies from thermal to just below the threshold for second chance fission. Current measurements of the mean number of prompt neutrons emitted in fission, together with less accurate measurements of the neutron energy spectra, place remarkably fine constraints on predictions of microscopic calculations. In particular, the total excitation energy of the nascent fragments must be specified to within 1 MeV to avoid disagreement with measurements of the mean neutron multiplicity. The combination of the Monte Carlo fission model with a statistical likelihood analysis also presents a powerful tool for the evaluation of fission neutron data. Of particular importance is the fission spectrum, which plays a key role in determining reactor criticality. We show that our approach can be used to develop an estimate of the fission spectrum with uncertainties several times smaller than current experimental uncertainties for outgoing neutron energies of less than 2 MeV.

  1. Database of prompt gamma rays from slow neutron capture for elemental analysis

    International Nuclear Information System (INIS)

    The increasing importance of prompt gamma ray activation analysis (PGAA) in a broad range of applications is evident, and has been emphasized at many meetings related to this topic. Furthermore, an Advisory Group Meeting (AGM) for the Coordination of the International Network of Nuclear Structure and Decay Data Evaluators concluded that there is a need for a complete library of gamma ray and cross-section data from cold and thermal neutron capture (the AGM was held in Budapest, 14-18 October 1996); this AGM also recommended the organization of an IAEA Coordinated Research Project (CRP) on this subject. The nuclear data programmes of the IAEA arose as a consequence of the advisory reviews of the International Nuclear Data Committee (INDC). At a biennial meeting in 1997, the INDC strongly recommended that the IAEA support new measurements and update the database on the analysis of prompt gamma ray activation induced by neutrons. As a consequence of the various recommendations, a CRP, entitled Development of a Database for Prompt Gamma Ray Neutron Activation Analysis (PGAA), was initiated in 1999. Prior to this project, several consultants had defined the scope, objectives and tasks of this CRP, as approved subsequently by the IAEA. Each CRP participant assumed responsibility for the execution of specific tasks. The results of their work and of other research were discussed and approved by the participants in Research Coordination Meetings (RCMs) held in 2000, 2001 and 2003. Prompt gamma ray activation analysis is a non-destructive radioanalytical method capable of rapid or simultaneous in situ multielement analyses across the entire periodic table, from hydrogen to uranium. However, inaccurate and incomplete data have been a significant hindrance in the qualitative and quantitative analyses of complicated neutron capture gamma spectra by means of PGAA. Therefore, the main goal of the CRP was to improve the quality and quantity of the required data in order to make

  2. Fast digitization and discrimination of prompt neutron and photon signals using a novel silicon carbide detector

    International Nuclear Information System (INIS)

    Current requirements of some Homeland Security active interrogation projects for the detection of Special Nuclear Material (SNM) necessitate the development of faster inspection and acquisition capabilities. In order to do so, fast detectors which can operate during and shortly after intense interrogation radiation flashes are being developed. Novel silicon carbide (SiC) semiconductor Schottky diodes have been utilized as robust neutron and photon detectors in both pulsed photon and pulsed neutron fields and are being integrated into active inspection environments to allow exploitation of both prompt and delayed emissions. These detectors have demonstrated the capability of detecting both photon and neutron events during intense photon flashes typical of an active inspection environment. Beyond the inherent insensitivity of SiC to gamma radiation, fast digitization and processing has demonstrated that pulse shape discrimination (PSD) in combination with amplitude discrimination can further suppress unwanted gamma signals and extract fast neutron signatures. Usable neutron signals have been extracted from mixed radiation fields where the background has exceeded the signals of interest by >1000:1

  3. Prompt gamma activation analysis of boron in reference materials using diffracted polychromatic neutron beam

    International Nuclear Information System (INIS)

    Boron concentrations were analyzed for standard reference materials by prompt gamma activation analysis (PGAA). The measurements were performed at the SNU-KAERI PGAA facility installed at Hanaro, the research reactor of Korea Atomic Energy Research Institute (KAERI). The facility uses a diffracted polychromatic beam with a neutron flux of 7.9 x 107 n/cm2 s. Elemental sensitivity for boron was calibrated from the prompt gamma-ray spectra of boric acid samples containing 2-45 μg boron. The sensitivity of 2131 cps/mg-B was obtained from the linearity of the boron peak count rate versus the boron mass. The detection limit for boron was estimated to be 67 ng from an empty sample bag spectrum for a counting time of 10,000 s. The measured boron concentrations for standard reference materials showed good consistency with the certified or information values

  4. Prompt gamma activation analysis of boron in reference materials using diffracted polychromatic neutron beam

    Science.gov (United States)

    Byun, S. H.; Sun, G. M.; Choi, H. D.

    2004-01-01

    Boron concentrations were analyzed for standard reference materials by prompt gamma activation analysis (PGAA). The measurements were performed at the SNU-KAERI PGAA facility installed at Hanaro, the research reactor of Korea Atomic Energy Research Institute (KAERI). The facility uses a diffracted polychromatic beam with a neutron flux of 7.9 × 10 7 n/cm 2 s. Elemental sensitivity for boron was calibrated from the prompt gamma-ray spectra of boric acid samples containing 2-45 μg boron. The sensitivity of 2131 cps/mg-B was obtained from the linearity of the boron peak count rate versus the boron mass. The detection limit for boron was estimated to be 67 ng from an empty sample bag spectrum for a counting time of 10,000 s. The measured boron concentrations for standard reference materials showed good consistency with the certified or information values.

  5. Tomographic image of prompt gamma ray from boron neutron capture therapy: A Monte Carlo simulation study

    International Nuclear Information System (INIS)

    The resulting neutron captures in 10B are used for radiation therapy. The occurrence point of the characteristic 478 keV prompt gamma rays agrees with the neutron capture point. If these prompt gamma rays are detected by external instruments such as a gamma camera or single photon emission computed tomography (SPECT), the therapy region can be monitored during the treatment using images. A feasibility study and analysis of a reconstructed image using many projections (128) were conducted. The optimization of the detection system and a detailed neutron generator simulation were beyond the scope of this study. The possibility of extracting a 3D BNCT-SPECT image was confirmed using the Monte Carlo simulation and OSEM algorithm. The quality of the prompt gamma ray SPECT image obtained from BNCT was evaluated quantitatively using three different boron uptake regions and was shown to depend on the location and size relations. The prospects for obtaining an actual BNCT-SPECT image were also estimated from the quality of the simulated image and the simulation conditions. When multi tumor regions should be treated using the BNCT method, a reasonable model to determine how many useful images can be obtained from SPECT can be provided to the BNCT facilities based on the preceding imaging research. However, because the scope of this research was limited to checking the feasibility of 3D BNCT-SPECT image reconstruction using multiple projections, along with an evaluation of the image, some simulation conditions were taken from previous studies. In the future, a simulation will be conducted that includes optimized conditions for an actual BNCT facility, along with an imaging process for motion correction in BNCT. Although an excessively long simulation time was required to obtain enough events for image reconstruction, the feasibility of acquiring a 3D BNCT-SPECT image using multiple projections was confirmed using a Monte Carlo simulation, and a quantitative image analysis was

  6. Determination of carbon, nitrogen and phosphorus in cattail using cold neutron prompt-gamma activation analysis

    International Nuclear Information System (INIS)

    A method for the determination of carbon, nitrogen, and phosphorus in cattail using cold neutron prompt-gamma activation analysis (CNPGAA) has been developed and evaluated through the analysis of standard reference materials (SRM). After extensive preparation, approximately 400 mg cattail samples from the lower Apalachicola River floodplain were irradiated in the CNPGAA facility at the National Institute of Standards and Technology (NIST). The results of numerous field samples and two standard reference materials using the nuclear method show favorable comparison to results obtained by a CHNS/O analyzer. (author)

  7. Measurement of prompt neutron decay constant on uranium-plutonium metal assembly

    International Nuclear Information System (INIS)

    The prompt neutron decay constant α of the Uranium-Plutonium metal assembly was measured with Rossi-α technique at delay critical and sub-critical conditions, and then αc is obtained. The relationship between α with reactivity and α is analyzed with detector counts reciprocal. The comparison shows that the direct measured result under delay critical condition is 0.835 ± 0.005/μs, which error is 1/6 of that from Rossi-a and extrapolation methods. (authors)

  8. Prompt gamma-ray neutron activation analysis (PGNAA) system by using a 740 GBq 241Am-Be neutron source

    International Nuclear Information System (INIS)

    A PGNAA system consisting of a 740 GBq 241Am-Be neutron source and a gamma spectrometer with a n-type Ge (REGe) detector was installed at Ankara Nuclear Training and Research Center to measure the prompt gamma-rays produced by the interactions of thermal neutrons in the samples for the analysis of light elements such as B, P, S and Cl, and some trace elements with large cross sections (Cd, Hg, Sm, Gd, etc.). In the irradiation system, a 55 cm diameter cylinder tank filled with the water moderator comprises the neutron source placed in a polypropylene tube that was positioned in lead rings (internal diameter - 9 cm and outer diameter - 21 cm) in order to reduce the gamma rays emitted from the source such as 0.0596 MeV (241Am) and 4.43 MeV (0.6 gamma per neutron) from the 9Be(α, n) reaction in the source. The moderator tank was shielded with paraffin in all sides against fast neutrons. The thickness of paraffin at the front side of the tank is 28 cm and 18 cm at other sides. The neutron irradiation system was also shielded by using chevron lead bricks of 18 cm thickness. The background-prominent gamma-rays which is especially the 2.223 MeV gamma ray from the 1H(n, γ) reaction formed in hydrogenous materials used for neutron moderation was reduced remarkably in view of the permissible gamma dose for overall irradiation room. The neutrons thermalized in moderator travel through the hole with 6 cm diameter for the sample irradiation. The detector was shielded with Li2CO3 powder against thermal neutrons to avoid radiation damage and surrounded by additional lead bricks to reduce gamma-background. The measurements are carried out for efficiency calibration of the detector by using the standard source. The characteristics of PGNAA system with the isotopic neutron source and its analysis capability are discussed

  9. Derivation of a volume-averaged neutron diffusion equation; Atomos para el desarrollo de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez R, R.; Espinosa P, G. [UAM-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, Mexico D.F. 09340 (Mexico); Morales S, Jaime B. [UNAM, Laboratorio de Analisis en Ingenieria de Reactores Nucleares, Paseo Cuauhnahuac 8532, Jiutepec, Morelos 62550 (Mexico)]. e-mail: rvr@xanum.uam.mx

    2008-07-01

    This paper presents a general theoretical analysis of the problem of neutron motion in a nuclear reactor, where large variations on neutron cross sections normally preclude the use of the classical neutron diffusion equation. A volume-averaged neutron diffusion equation is derived which includes correction terms to diffusion and nuclear reaction effects. A method is presented to determine closure-relationships for the volume-averaged neutron diffusion equation (e.g., effective neutron diffusivity). In order to describe the distribution of neutrons in a highly heterogeneous configuration, it was necessary to extend the classical neutron diffusion equation. Thus, the volume averaged diffusion equation include two corrections factor: the first correction is related with the absorption process of the neutron and the second correction is a contribution to the neutron diffusion, both parameters are related to neutron effects on the interface of a heterogeneous configuration. (Author)

  10. MEASUREMENT OF PROMPT NEUTRON SPECTRA OF 238U FISSION INDUCED BY 10.17 AND 12.12 MeV NEUTRONS

    Institute of Scientific and Technical Information of China (English)

    李安利; 白希祥; 等

    1994-01-01

    Experimental method to measure the prompt neutron spectra of 238U fission induced by fast neutrons has been developed at HI-13 Tandem Van de Graaff Accelerator Laboratory of CIAE.These techniques employ a multi-segment fission chamber and two liquid scintillator neutron detectors.TOF(time of flight)techniques are used for primary neutrons to select the fission events induced by monoenergetic neutron from 2H(d,n) reactions instead of breakup neutrons from 2H(d,np) reactions.The fission neutron TOF spectra are measured in coincidence with the fission fragments to distinguish fission neutrons from other secondary neutrons.The method permits measurements to a fairly good accuracy under large neutron and gamma ray background.The techniques are described and experimental spectra are presented.

  11. Prompt gamma-ray analysis using cold and thermal guided neutron beams at JAERI.

    Science.gov (United States)

    Yonezawa, C

    1999-01-01

    A highly sensitive neutron-induced prompt gamma-ray analysis (PGA) system, usable at both cold and thermal neutron beam guides of JRR-3M, has been constructed. The system was designed to achieve the lowest gamma-ray background by using lithium fluoride tiles as neutron shielding, by placing the samples in a He atmosphere and by using a Ge-bismuth germanate detector system for Compton suppression. The gamma-ray spectrometer can acquire three modes of spectra simultaneously: single, Compton suppression, and pair modes. Because of the low-energy guided neutron beams and the low-background system, analytical sensitivities and detection limits better than those in usual PGA systems have been achieved. Boron and multielemental determination by a comparative standardization have been investigated, and accuracy, precision, and detection limits for the elements in various materials were evaluated. The system has been applied to the determination of B and multielements in samples of various fields such as medical, environmental, and geological sciences. PMID:10676516

  12. Application of cold neutron prompt-gamma activation analysis in environmental studies of aquatic plants

    International Nuclear Information System (INIS)

    This paper describes the use of cold-neutron prompt-gamma activation analysis (CNPGAA) to determine carbon, nitrogen, and phosphorus in the aquatic plant Typha domingensis, commonly known as cattail, during spring and fall seasons. According to studies of the Florida Everglades, cattail replaces sawgrass as a result of nutrient enrichment from farm water runoff. Nutrient enrichment, especially phosphorus, in sediment and the water column can lead to undesirable expansion. Early signs of this expansion are apparent in the Apalachicola River floodplain near Apalachicola, Florida, USA. This research project is designed to use cattails as biomonitors of nutrient enrichment in the lower Apalachicola River floodplain. Determination of carbon, nitrogen, and phosphorus in cattail using cold neutron prompt-gamma activation has been developed in our previous studies at the CNPGAA facility at the National Institute of Standards and Technology (NIST), USA. The results of numerous field samples, collected from the study area during spring and fall seasons in 2002, will be presented in this paper. (author)

  13. GPU-based prompt gamma ray imaging from boron neutron capture therapy

    International Nuclear Information System (INIS)

    Purpose: The purpose of this research is to perform the fast reconstruction of a prompt gamma ray image using a graphics processing unit (GPU) computation from boron neutron capture therapy (BNCT) simulations. Methods: To evaluate the accuracy of the reconstructed image, a phantom including four boron uptake regions (BURs) was used in the simulation. After the Monte Carlo simulation of the BNCT, the modified ordered subset expectation maximization reconstruction algorithm using the GPU computation was used to reconstruct the images with fewer projections. The computation times for image reconstruction were compared between the GPU and the central processing unit (CPU). Also, the accuracy of the reconstructed image was evaluated by a receiver operating characteristic (ROC) curve analysis. Results: The image reconstruction time using the GPU was 196 times faster than the conventional reconstruction time using the CPU. For the four BURs, the area under curve values from the ROC curve were 0.6726 (A-region), 0.6890 (B-region), 0.7384 (C-region), and 0.8009 (D-region). Conclusions: The tomographic image using the prompt gamma ray event from the BNCT simulation was acquired using the GPU computation in order to perform a fast reconstruction during treatment. The authors verified the feasibility of the prompt gamma ray image reconstruction using the GPU computation for BNCT simulations

  14. Database of prompt gamma rays from slow neutron capture for elemental analysis

    International Nuclear Information System (INIS)

    The increasing importance of Prompt Gamma-ray Activation Analysis (PGAA) in a broad range of applications is evident, and has been emphasized at many meetings related to this topic (e.g., Technical Consultants' Meeting, Use of neutron beams for low- and medium-flux research reactors: radiography and materials characterizations, IAEA Vienna, 4-7 May 1993, IAEA-TECDOC-837, 1993). Furthermore, an Advisory Group Meeting (AGM) for the Coordination of the Nuclear Structure and Decay Data Evaluators Network has stated that there is a need for a complete and consistent library of cold- and thermal neutron capture gamma ray and cross-section data (AGM held at Budapest,14-18 October 1996, INDC(NDS)-363); this AGM also recommended the organization of an IAEA CRP on the subject. The International Nuclear Data Committee (INDC) is the primary advisory body to the IAEA Nuclear Data Section on their nuclear data programs. At a biennial meeting in 1997, the INDC strongly recommended that the Nuclear Data Section support new measurements and update the database on Neutron-induced Prompt Gamma-ray Activation Analysis (21st INDC meeting, INDC/P(97)-20). As a consequence of the various recommendations, a CRP on ''Development of a Database for Prompt Gamma-ray Neutron Activation Analysis (PGAA)'' was initiated in 1999. Prior to this project, several consultants had defined the scope, objectives and tasks, as approved subsequently by the IAEA. Each CRP participant assumed responsibility for the execution of specific tasks. The results of their and other research work were discussed and approved by the participants in research co-ordination meetings (see Summary reports: INDC(NDS)-411, 2000; INDC(NDS)-424, 2001; and INDC(NDS)-443, 200). PGAA is a non-destructive radioanalytical method, capable of rapid or simultaneous ''in-situ'' multi-element analyses across the entire Periodic Table, from hydrogen to uranium. However, inaccurate and incomplete data were a significant hindrance in the

  15. The effect of neutron skin on inclusive prompt photon production in Pb~+~Pb collisions at the LHC

    CERN Document Server

    De, Somnath

    2016-01-01

    Recent experiments on lead (\\textrm{$Pb_{82}^{208}$}) nuclei have observed the celebrated phenomenon of neutron skin-thickness of low energy nuclear physics. The skin-thickness provides a measure of extension of spatial distribution of neutrons inside the atomic nucleus than protons. We have studied the effect of neutron skin-thickness on inclusive prompt photon production in Pb~+~Pb collisions at the Large Hadron Collider energies. We have calculated the \\textquoteleft central-to-peripheral ratio\\textquoteright ($R_\\textrm{cp}$) of prompt photon production with and without accounting for neutron skin effect. The neutron skin causes a characteristic enhancement in the ratio, in particular at forward rapidity, which is distinguishable in our calculation. However a very precise direct photon measurement up to large transverse momenta would be necessary to constrain the feature in experiment.

  16. Imaging of heterogeneous materials by prompt gamma-ray neutron activation analysis

    International Nuclear Information System (INIS)

    We have used a Tomographic Gamma Scanner (TGS) to produce tomographic Prompt Gamma-Ray Neutron Activation Imaging of heterogeneous matrices [T.H. Prettyman, R.J. Estep, G.A. Sheppard, Trans. Am. Nucl. Soc. 69 (1993) 183-184]. The TGS was modified by the addition of graphite reflectors that contain isotopic neutron sources for sample interrogation. We are in the process of developing the analysis methodology necessary for a quantitative assay of large containers of heterogeneous material. This nondestructive analysis technique can be used for material characterization and the determination of neutron assay correction factors. The most difficult question to be answered is the determination of the source to sample coupling term. To assist in the determination of the coupling term we have obtained images for a range of samples that are very well characterized; such as, homogenous pseudo one-dimensional samples to three-dimensional heterogeneous samples. We then compare the measurements to Monte Carlo N-particle calculations. For an accurate quantitative measurement it is also necessary to determine the sample gamma-ray self attenuation at higher gamma-ray energies, namely pair production should be incorporated into the analysis codes

  17. Matrix effects in compositional analysis of bulk materials by PGNAA (prompt gamma/neutron activation analysis). Final report

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, V.C.; Sandquist, G.M.; Merrell, G.B.; Gozani, T.

    1984-08-01

    This feasibility study has identified and evaluated the influence of important matrix effects which arise in the commercial application of prompt gamma/neutron activation analysis (PGNAA) methods to bulk-coal analysis as follows: neutron moderation and absorption changes; gamma-ray attenuation in the sample; sample density and volume changes. The neutron-induced capture gamma spectra were found to vary in a similar, predictable manner for all neutron absorbers found in coal such as hydrogen, boron, nitrogen, chlorine, and sulfur. Three different models have been proposed from this study to analyze coal by PGNAA methods and account for the significant matrix effects arising from hydrogen variation and other system perturbations.

  18. Matrix effects in compositional analysis of bulk materials by PGNAA (prompt gamma/neutron activation analysis). Final report

    International Nuclear Information System (INIS)

    This feasibility study has identified and evaluated the influence of important matrix effects which arise in the commercial application of prompt gamma/neutron activation analysis (PGNAA) methods to bulk-coal analysis as follows: neutron moderation and absorption changes; gamma-ray attenuation in the sample; sample density and volume changes. The neutron-induced capture gamma spectra were found to vary in a similar, predictable manner for all neutron absorbers found in coal such as hydrogen, boron, nitrogen, chlorine, and sulfur. Three different models have been proposed from this study to analyze coal by PGNAA methods and account for the significant matrix effects arising from hydrogen variation and other system perturbations

  19. 239Pu Prompt Fission Neutron Spectra Impact on a Set of Criticality and Experimental Reactor Benchmarks

    Science.gov (United States)

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

    2014-04-01

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

  20. Method for measuring prompt gamma-rays generated by D-T neutrons bombarding a depleted uranium spherical shell

    OpenAIRE

    Qin, Jianguo; Lai, Caifeng; Jiang, Li; Liu, Rong; Zhang, Xinwei; Ye, Bangjiao; Zhu, Tonghua

    2015-01-01

    The prompt gamma-ray spectrum from depleted uranium (DU) spherical shells induced by 14 MeV D-T neutrons is measured. Monte Carlo (MC) simulation gives the largest prompt gamma flux with the optimal thickness of the DU spherical shells 3-5 cm and the optimal frequency of neutron pulse 1 MHz. The method of time of flight and pulse shape coincidence with energy (DC-TOF) is proposed, and the subtraction of the background gamma-rays discussed in detail. The electron recoil spectrum and time spect...

  1. Criticality prompt gamma and neutron dose equations validated by Monte Carlo analyses and compared to known criticality accident doses

    Science.gov (United States)

    Hochhalter, Eugene

    The United States (US) Department of Energy [DOE] and the Nuclear Regulatory Commission [NRC] have provided the nuclear industry with requirements, goals, and objectives for the preparation of safety analysis and the finalization of that safety analysis in the form of a documented safety analysis (DSA) and technical safety requirements (TSRs). The deterministic guidance provided by the NRC in Regulatory Guide (RG) 3.33 for calculating the prompt gamma and neutron doses from a criticality has a number of potential issues associated with the semi-empirical equations, which make these equations potentially out dated. The NRC guidance for estimating the prompt gamma and neutron doses to a facility worker due to an accidental criticality was withdrawn without newer deterministic guidance being issued. This research project determined the original basis for the RG prompt gamma and neutron equations, evaluated the potential issues associated with the RG 3.33 prompt gamma and neutron equations, and modified the RG 3.33 point source prompt gamma and neutron equations to calculate the doses for the selected set of criticality accidents. The criticality accidents addressed by this dissertation include: 1. U-235, Pu-239, and Pu-241 point source criticality, 2. U-235, Pu-239, and Pu-241 sphere source criticality, 3. Uranyl nitrate and plutonium nitrate solutions in a cylindrical process vessel and 4. Low level waste in 55-gallon and 30-gallon drums. The prompt gamma and neutron equation doses (RG 3.33/3.34/3.35) are compared to actual nuclear industry criticality accident worker doses to assess the conservatism of the RG equations. Finally, the RG 3.33 prompt gamma and neutron dose equations are compared to MCNP5 results to investigate consistency with respect to the modified prompt gamma and neutron dose equations and the representative dose estimates for each of the criticality configurations (point source, spherical source, and cylindrical source). Knowledge and accurate

  2. Fission cross-sections, prompt fission neutron and γ-ray emission in request for nuclear applications

    Directory of Open Access Journals (Sweden)

    Hambsch F.-J.

    2016-01-01

    Full Text Available In recent years JRC-IRMM has been investigating fission cross-sections of 240,242Pu in the fast-neutron energy range relevant for innovative reactor systems and requested in the High Priority Request List (HPRL of the OECD/Nuclear Energy Agency (NEA. In addition to that, prompt neutron multiplicities are being investigated for the major isotopes 235U, 239Pu in the neutron-resonance region using a newly developed scintillation detector array (SCINTIA and an innovative modification of the Frisch-grid ionisation chamber for fission-fragment detection. These data are highly relevant for improved neutron data evaluation and requested by the OECD/Working Party on Evaluation Cooperation (WPEC. Thirdly, also prompt fission γ-ray emission is investigated using highly efficient lanthanide-halide detectors with superior timing resolution. Again, those data are requested in the HPRL for major actinides to solve open questions on an under-prediction of decay heat in nuclear reactors. The information on prompt fission neutron and γ-ray emission is crucial for benchmarking nuclear models to study the de-excitation process of neutron-rich fission fragments. Information on γ-ray emission probabilities is also useful in decommissioning exercises on damaged nuclear power plants like Fukushima Daiichi to which JRC-IRMM is contributing. The results on the 240,242Pu fission cross section, 235U prompt neutron multiplicity in the resonance region and correlations with fission fragments and prompt γ-ray emission for several isotopes will be presented and put into perspective.

  3. Fission cross-sections, prompt fission neutron and γ-ray emission in request for nuclear applications

    Science.gov (United States)

    Hambsch, F.-J.; Salvador-Castiñeira, P.; Oberstedt, S.; Göök, A.; Billnert, R.

    2016-06-01

    In recent years JRC-IRMM has been investigating fission cross-sections of 240,242Pu in the fast-neutron energy range relevant for innovative reactor systems and requested in the High Priority Request List (HPRL) of the OECD/Nuclear Energy Agency (NEA). In addition to that, prompt neutron multiplicities are being investigated for the major isotopes 235U, 239Pu in the neutron-resonance region using a newly developed scintillation detector array (SCINTIA) and an innovative modification of the Frisch-grid ionisation chamber for fission-fragment detection. These data are highly relevant for improved neutron data evaluation and requested by the OECD/Working Party on Evaluation Cooperation (WPEC). Thirdly, also prompt fission γ-ray emission is investigated using highly efficient lanthanide-halide detectors with superior timing resolution. Again, those data are requested in the HPRL for major actinides to solve open questions on an under-prediction of decay heat in nuclear reactors. The information on prompt fission neutron and γ-ray emission is crucial for benchmarking nuclear models to study the de-excitation process of neutron-rich fission fragments. Information on γ-ray emission probabilities is also useful in decommissioning exercises on damaged nuclear power plants like Fukushima Daiichi to which JRC-IRMM is contributing. The results on the 240,242Pu fission cross section, 235U prompt neutron multiplicity in the resonance region and correlations with fission fragments and prompt γ-ray emission for several isotopes will be presented and put into perspective.

  4. The optimization of gamma spectra processing in prompt gamma neutron activation analysis (PGNAA)

    Energy Technology Data Exchange (ETDEWEB)

    Pinault, Jean-Louis [IAEA Expert, 96 rue du Port David, 45370 Dry (France)], E-mail: jeanlouis_pinault@hotmail.fr; Solis, Jose [Instituto Peruano de Energia Nuclear, Av. Canada No. 1470, San Borja, Lima 41 (Peru)

    2009-04-15

    The uncertainty of the elemental analysis is one of the major factors governing the utility of on-line Prompt Gamma Neutron Activation Analysis (PGNAA) in the blending and sorting of bulk materials. In this paper, a general method applicable to Gamma spectra processing is presented and applied to PGNAA in mineral industry. Based on the Fourier transform of spectra and their de-correlation in the Fourier space (the improvement of the conditioning of the correlation matrix), processing of overlapping of characteristic peaks minimizes the propagation of random errors, which optimizes the accuracy and decreases the detection limits of elemental analyses. In comparison with classical methods based on the linear combinations of relevant regions of spectra the improvement may be considerable, especially when several elements are interfering. The method is applied to four case stories covering both borehole logging and on-line analysis on conveyor belt of raw materials.

  5. On the accuracy of protein determination in large biological samples by prompt gamma neutron activation analysis

    International Nuclear Information System (INIS)

    A prompt gamma neutron activation analysis (PGNAA) facility has been developed for the determination of nitrogen and thus total protein in large volume biological samples or the whole body of small animals. In the present work, the accuracy of nitrogen determination by PGNAA in phantoms of known composition as well as in four raw ground meat samples of about 1 kg mass was examined. Dumas combustion and Kjeldahl techniques were also used for the assessment of nitrogen concentration in the meat samples. No statistically significant differences were found between the concentrations assessed by the three techniques. The results of this work demonstrate the applicability of PGNAA for the assessment of total protein in biological samples of 0.25-1.5 kg mass, such as a meat sample or the body of small animal even in vivo with an equivalent radiation dose of about 40 mSv

  6. Stabilization of prompt gamma-ray neutron activation analysis (PGNAA) spectra from NaI detectors

    Energy Technology Data Exchange (ETDEWEB)

    Metwally, W.A.; Gardner, R.P. E-mail: gardner@ncsu.edu

    2004-06-11

    NaI detectors are still used frequently in industrial Prompt Gamma-Ray Neutron Activation Analysis applications such as in bulk material analysis. They have the advantages of being efficient for high-energy gamma rays, being relatively rugged, and being able to be used without cooling. When using NaI detectors, and consequently photomultiplier tubes, the quality of the data can drastically deteriorate through gain and zero shifts that result in spectral smearing due to temperature and/or counting rate changes. A new offline approach is presented to stabilize the NaI spectral drift. The approach is not sensitive to the cause of the drift and takes into account the NaI and ADC non-linearities. Peak resolution is improved substantially when this approach is used in the presence of spectral drift.

  7. Stabilization of prompt gamma-ray neutron activation analysis (PGNAA) spectra from NaI detectors

    Science.gov (United States)

    Metwally, W. A.; Gardner, R. P.

    2004-06-01

    NaI detectors are still used frequently in industrial Prompt Gamma-Ray Neutron Activation Analysis applications such as in bulk material analysis. They have the advantages of being efficient for high-energy gamma rays, being relatively rugged, and being able to be used without cooling. When using NaI detectors, and consequently photomultiplier tubes, the quality of the data can drastically deteriorate through gain and zero shifts that result in spectral smearing due to temperature and/or counting rate changes. A new offline approach is presented to stabilize the NaI spectral drift. The approach is not sensitive to the cause of the drift and takes into account the NaI and ADC non-linearities. Peak resolution is improved substantially when this approach is used in the presence of spectral drift.

  8. The optimization of gamma spectra processing in prompt gamma neutron activation analysis (PGNAA)

    Science.gov (United States)

    Pinault, Jean-Louis; Solis, Jose

    2009-04-01

    The uncertainty of the elemental analysis is one of the major factors governing the utility of on-line Prompt Gamma Neutron Activation Analysis (PGNAA) in the blending and sorting of bulk materials. In this paper, a general method applicable to Gamma spectra processing is presented and applied to PGNAA in mineral industry. Based on the Fourier transform of spectra and their de-correlation in the Fourier space (the improvement of the conditioning of the correlation matrix), processing of overlapping of characteristic peaks minimizes the propagation of random errors, which optimizes the accuracy and decreases the detection limits of elemental analyses. In comparison with classical methods based on the linear combinations of relevant regions of spectra the improvement may be considerable, especially when several elements are interfering. The method is applied to four case stories covering both borehole logging and on-line analysis on conveyor belt of raw materials.

  9. The optimization of gamma spectra processing in prompt gamma neutron activation analysis (PGNAA)

    International Nuclear Information System (INIS)

    The uncertainty of the elemental analysis is one of the major factors governing the utility of on-line Prompt Gamma Neutron Activation Analysis (PGNAA) in the blending and sorting of bulk materials. In this paper, a general method applicable to Gamma spectra processing is presented and applied to PGNAA in mineral industry. Based on the Fourier transform of spectra and their de-correlation in the Fourier space (the improvement of the conditioning of the correlation matrix), processing of overlapping of characteristic peaks minimizes the propagation of random errors, which optimizes the accuracy and decreases the detection limits of elemental analyses. In comparison with classical methods based on the linear combinations of relevant regions of spectra the improvement may be considerable, especially when several elements are interfering. The method is applied to four case stories covering both borehole logging and on-line analysis on conveyor belt of raw materials.

  10. Prompt gamma ray diagnostics and enhanced hadron-therapy using neutron-free nuclear reactions

    CERN Document Server

    Giuffrida, L; Cirrone, G A P; Picciotto, A; Korn, G

    2016-01-01

    We propose a series of simulations about the potential use of Boron isotopes to trigger neutron-free (aneutronic) nuclear reactions in cancer cells through the interaction with an incoming energetic proton beam, thus resulting in the emission of characteristic prompt gamma radiation (429 keV, 718 keV and 1435 keV). Furthermore assuming that the Boron isotopes are absorbed in cancer cells, the three alpha-particles produced in each p-11B aneutronic nuclear fusion reactions can potentially result in the enhancement of the biological dose absorbed in the tumor region since these multi-MeV alpha-particles are stopped inside the single cancer cell, thus allowing to spare the surrounding tissues. Although a similar approach based on the use of 11B nuclei has been proposed in [1], our work demonstrate, using Monte Carlo simulations, the crucial importance of the use of 10B nuclei (in a solution containing also 11B) for the generation of prompt gamma-rays, which can be applied to medical imaging. In fact, we demonstr...

  11. Prompt gamma neutron activation analysis facility at the RA-6 research reactor

    International Nuclear Information System (INIS)

    A prompt gamma neutron activation activation analysis facility was developed at the 500 kw thermal power RA-6 research reactor of the Bariloche Atomic Center, Argentina.This facility consist of a radial beam port with external positioning of the sample.The gamma radiation is reduced by a bismuth filter placed inside the extraction tube and the beam diameter is limited by a set of two collimators up to 5 cm.The neutron flux at the sample position is 7 106 n/cm2s with a Cadmium ratio of 20/1.The gamma detector is a 50 % efficiency type p HPGe rounded by a NaI(Tl) for Compton suppressioning.The gamma spectra is measured through 0 to 8.5 MeV.The background have counting rate of 350 cps without sample. In this work is shown the efficiency curve, the calculed sensibilities and the lower detection limits for B, Cd, Sm, Gd, H, Cl, Hg, Eu, Ti, Ag, Au, Mo. The RA-6's PGNAA facility is fully working, although the analytic capacity is under improvement

  12. Method for measuring prompt gamma-rays generated by D-T neutrons bombarding a depleted uranium spherical shell

    CERN Document Server

    Qin, Jianguo; Jiang, Li; Liu, Rong; Zhang, Xinwei; Ye, Bangjiao; Zhu, Tonghua

    2015-01-01

    The prompt gamma-ray spectrum from depleted uranium (DU) spherical shells induced by 14 MeV D-T neutrons is measured. Monte Carlo (MC) simulation gives the largest prompt gamma flux with the optimal thickness of the DU spherical shells 3-5 cm and the optimal frequency of neutron pulse 1 MHz. The method of time of flight and pulse shape coincidence with energy (DC-TOF) is proposed, and the subtraction of the background gamma-rays discussed in detail. The electron recoil spectrum and time spectrum of the prompt gamma-rays are obtained based on a 2"*2" BC501A liquid scintillator detector. The energy spectrum and time spectrum of prompt gamma-rays are obtained based on an iterative unfolding method that can remove the influence of {\\gamma}-rays response matrix and pulsed neutron shape. The measured time spectrum and the calculated results are roughly consistent with each other. Experimental prompt gamma-ray spectrum in the 0.4-3 MeV energy region agree well with MC simulation based on the ENDF/BVI.5 library, and ...

  13. Method for measuring prompt γ-rays generated by D-T neutrons bombarding a depleted uranium spherical shell

    Science.gov (United States)

    Qin, Jian-Guo; Lai, Cai-Feng; Jiang, Li; Liu, Rong Zhang, Xin-Wei; Ye, Bang-Jiao; Zhu, Tong-Hua

    2016-01-01

    The prompt γ-ray spectrum from depleted uranium (DU) spherical shells induced by 14 MeV D-T neutrons is measured. Monte Carlo (MC) simulation gives the largest prompt γ flux with the optimal thickness of the DU spherical shells 3-5 cm and the optimal frequency of neutron pulse 1 MHz. The method of time of flight and pulse shape coincidence with energy (DC-TOF) is proposed, and the subtraction of the background γ-rays discussed in detail. The electron recoil spectrum and time spectrum of the prompt γ-rays are obtained based on a 2″×2″ BC501A liquid scintillator detector. The energy spectrum and time spectrum of prompt γ-rays are obtained based on an iterative unfolding method that can remove the influence of γ-rays response matrix and pulsed neutron shape. The measured time spectrum and the calculated results are roughly consistent with each other. Experimental prompt γ-ray spectrum in the 0.4-3 MeV energy region agrees well with MC simulation based on the ENDF/BVI.5 library, and the discrepancies for the integral quantities of γ-rays of energy 0.4-1 MeV and 1-3 MeV are 9.2% and 1.1%, respectively. Supported by National Special Magnetic Confinement Fusion Energy Research, China (2015GB108001) and National Natural Science Foundation of China (91226104)

  14. Thermal-neutron-capture prompt-gamma emission spectra of representative coals. [1. 5 to 11 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Herzenberg, C L; Olson, I K

    1981-12-01

    Prompt gamma ray emission spectra have been calculated from 1.5 to 11 MeV for a wide range of coal compositions exposed to a thermal neutron flux. These include contributions to the spectra from all of the major and minor elements present in the coals. Characteristics of the spectra are discussed and correlated with the coal compositions.

  15. T-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons

    Science.gov (United States)

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Kopach, Yu. N.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2011-05-01

    Study of the T-odd three-vector correlation in the emission of prompt neutrons from 235U fission by polarized cold neutrons has been continued at the facility MEPHISTO of the FRM II reactor (Technical University of Munich). The sought correlation was not found within experimental error of 2.3 × 10-5. The upper limit for the asymmetry coefficient has been set to | D n | < 6 × 10-5 at 99% confidence level, whereas for ternary fission correlation coefficient D α = (170±20) × 10-5. This limit casts doubt on a model that explains the three-vector correlation in ternary fission by the Coriolis mechanism. At the same time, five-vector correlation in the emission of prompt fission neutrons has been measured, which describes the rotation of the fissioning nucleus at the moment it breaks (ROT effect). At the angle 22.5° to the fission axis, the correlation coefficient was found to be (1.57 ± 0.20) × 10-4, while at the angle of 67.5° it is zero within the experimental uncertainty. The existence of ROT effect in the emission of prompt fission neutrons can be explained by the anisotropy of neutron emission in the rest frame of the fragment (fission fragments are aligned with respect to the axis of deformation of the fissioning nucleus), similar to the mechanism of ROT effect in the emission of prompt γ-rays.

  16. Non destructive multi elemental analysis using prompt gamma neutron activation analysis techniques: Preliminary results for concrete sample

    International Nuclear Information System (INIS)

    In this study, principle of prompt gamma neutron activation analysis has been used as a technique to determine the elements in the sample. The system consists of collimated isotopic neutron source, Cf-252 with HPGe detector and Multichannel Analysis (MCA). Concrete with size of 10×10×10 cm3 and 15×15×15 cm3 were analysed as sample. When neutrons enter and interact with elements in the concrete, the neutron capture reaction will occur and produce characteristic prompt gamma ray of the elements. The preliminary result of this study demonstrate the major element in the concrete was determined such as Si, Mg, Ca, Al, Fe and H as well as others element, such as Cl by analysis the gamma ray lines respectively. The results obtained were compared with NAA and XRF techniques as a part of reference and validation. The potential and the capability of neutron induced prompt gamma as tool for multi elemental analysis qualitatively to identify the elements present in the concrete sample discussed

  17. Determination and validation of prompt k0-factors with a monochromatic neutron beam at the Dhruva reactor

    Science.gov (United States)

    Nair, A. G. C.; Acharya, R.; Sudarshan, K.; Tripathi, R.; Reddy, A. V. R.; Goswami, A.

    2006-08-01

    Prompt Gamma-ray Neutron Activation Analysis (PGNAA) was carried out using a reflected neutron beam of 0.018 eV energy at the Dhruva research reactor, Bhabha Atomic Research Centre, Mumbai, India. The neutron beam characteristics, such as dimension, homogeneity and thermal equivalent flux were evaluated. The prompt k0-factors of about 15 elements were determined versus the 1951.1 keV gamma-ray of the 35Cl(n,γ) reaction. These prompt k0-factors are compared with the recommended k0-values for thermal neutrons and were found to be in good agreement, except for Gd, Cd and Hg. The internal mono-standard method was applied to analyze a meteorite and a stainless steel alloy (SS 316 M) using the recommended k0-values from the literature. As to the alloy, the measured concentrations were in good agreement with the nominal composition. For the meteorite sample, the concentrations of the major elements were in good agreement with the values determined using conventional neutron activation analysis.

  18. Database of prompt gamma rays from slow neutron capture forelemental analysis

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, R.B.; Choi, H.D.; Lindstrom, R.M.; Molnar, G.L.; Mughabghab, S.F.; Paviotti-Corcuera, R.; Revay, Zs; Trkov, A.; Zhou,C.M.; Zerkin, V.

    2004-12-31

    The increasing importance of Prompt Gamma-ray ActivationAnalysis (PGAA) in a broad range of applications is evident, and has beenemphasized at many meetings related to this topic (e.g., TechnicalConsultants' Meeting, Use of neutron beams for low- andmedium-fluxresearch reactors: radiography and materialscharacterizations, IAEA Vienna, 4-7 May 1993, IAEA-TECDOC-837, 1993).Furthermore, an Advisory Group Meeting (AGM) for the Coordination of theNuclear Structure and Decay Data Evaluators Network has stated that thereis a need for a complete and consistent library of cold- and thermalneutron capture gammaray and cross-section data (AGM held at Budapest,14-18 October 1996, INDC(NDS)-363); this AGM also recommended theorganization of an IAEA CRP on the subject. The International NuclearData Committee (INDC) is the primary advisory body to the IAEA NuclearData Section on their nuclear data programmes. At a biennial meeting in1997, the INDC strongly recommended that the Nuclear Data Section supportnew measurements andupdate the database on Neutron-induced PromptGamma-ray Activation Analysis (21st INDC meeting, INDC/P(97)-20). As aconsequence of the various recommendations, a CRP on "Development of aDatabase for Prompt Gamma-ray Neutron Activation Analysis (PGAA)" wasinitiated in 1999. Prior to this project, several consultants had definedthe scope, objectives and tasks, as approved subsequently by the IAEA.Each CRP participant assumed responsibility for the execution of specifictasks. The results of their and other research work were discussed andapproved by the participants in research co-ordination meetings (seeSummary reports: INDC(NDS)-411, 2000; INDC(NDS)-424, 2001; andINDC(NDS)-443, 200). PGAA is a non-destructive radioanalytical method,capable of rapid or simultaneous "in-situ" multi-element analyses acrossthe entire Periodic Table, from hydrogen to uranium. However, inaccurateand incomplete data were a significant hindrance in the qualitative andquantitative

  19. Body composition to climate change studies - the many facets of neutron induced prompt gamma-ray analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mitra,S.

    2008-11-17

    In-vivo body composition analysis of humans and animals and in-situ analysis of soil using fast neutron inelastic scattering and thermal neutron capture induced prompt-gamma rays have been described. By measuring carbon (C), nitrogen (N) and oxygen (O), protein, fat and water are determined. C determination in soil has become important for understanding below ground carbon sequestration process in the light of climate change studies. Various neutron sources ranging from radio isotopic to compact 14 MeV neutron generators employing the associated particle neutron time-of-flight technique or micro-second pulsing were implemented. Gamma spectroscopy using recently developed digital multi-channel analyzers has also been described.

  20. Provenance study of amerindian pottery figurines with prompt-gamma neutron activation analysis

    International Nuclear Information System (INIS)

    A prompt-gamma activation analysis facility has been under development at the Budapest Neutron Centre since 1996. Its applicability to archaeological research has already been established by several studies. This facility has been used in collaboration with the Universidad Simon Bolivar, Venezuela to determine the provenance of some pre-Hispanic pottery figurines by the use of PGNAA. Samples were selected from five archaeological sites excavated in the Los Roques Archipelago, where almost five hundred figurines were recovered in four sites. Amerindian groups from adjacent Venezuela mainland were identified as island sites' occupants, between 1200 A.D. and the European contact period. For preliminary research purposes three samples from Lake Valencia Basin and five from Los Roques were selected. For the study discussed here a total of 40 samples were used. Microscopic properties of pottery, such as chemical composition, can shed light on its origin, place of manufacture, raw material origin, production method and trade, among others. PGNAA was selected as the most convenient non-destructive method to measure major and trace elements. We show that these results contribute in determining the origin of the pottery. The samples were irradiated with a cold (20K) neutron beam of 5·107 cm-2 s-1 and the prompt-gamma ray spectra were collected with an HPGe-BGO detector system. The element identification and concentration calculations were performed based on the Center data library. We were able to determine the major components of H2O, Na2O, MgO, Al2O3, SiO2, K2O, CaO, TiO2, and MnO, Fe2O3 parallel with trace elements of B, S, Cl, Sc, V, Cr, Ba, Sm, Eu, and Gd. The preliminary measurements of the concentration of K2O, Cl and Cr showed significant differences between the samples from Lake Valencia Basin (mainland) and from Los Roques Islands. However, the discussed here analysis of a large set of samples, from both the mainland and the islands sites, provides support to the

  1. Improved Techniques for Low-Flux Measurement of Prompt Neutron Lifetime, Conversion Ratio and Fast Spectra

    International Nuclear Information System (INIS)

    Various statistical methods for the measurement of the ratio of prompt neutron lifetime to delayed fraction have been used in the zero-power reactor programme. One method was originated here, i.e. analysis of reactor noise with a bandpass filter, and others such as the measurement of the frequency of delayed coincidences among counter pulses as a function of delay time and the measurement of the relative variance of time integrals of the neutron flux as a function of integrating time have been refined. The areas of most advantageous application of the various methods have been studied. Attention has also been given to the interpretation of the results of these measurements, and it has been shown that interpretation based on a simple kinetics model is applicable to a wide range of practical cases. Several improvements in our original activation method for the low flux determination of the ratio of production to destruction of fissile material are described. These include the application of very sensitive radiochemical techniques as a confirming procedure; correction for extraneous counts, utilizing foils of different enrichments for the contribution of fission of the fertile material to the fission- product activity and foils exposed to different spectra for fission-related counts in the capture determination; and the use of coincidence counting for the detection of Np239 decay. Obtaining a value for conversion ratio from the activation data requires a knowledge of the ratio of captures to fissions in the fuel, α. No accurate experimental method now exists for the measurement of this quantity in a low flux reactor, but several methods which might make feasible such a determination are being explored. Three of the more promising techniques are outlined. Efforts to develop a small fast neutron spectrometer of good stability, resolution and sensitivity for in-pile measurements of neutron spectra in the energy region of tens and hundreds of kilovolts have been

  2. Feasibility study of prompt gamma neutron activation analysis (PGNAA) of explosives simulants and bulk material using DD/DT neutron generator

    Science.gov (United States)

    Bishnoi, S.; Sarkar, P. S.; Patel, T.; Adhikari, P. S.; Sinha, Amar

    2013-04-01

    Elemental characterization of low Z elements (C,H,Cl,Fe) inside bulk materials were performed using PGNAA technique. Samples having elemental composition similar to explosives were used for such experimentations using moderated DD neutrons as well as DT(14MeV) neutrons. We could observe characteristic prompt capture gamma rays of hydrogen (2.224MeV), nitrogen (10.83 MeV), chlorine (6.11 MeV) and Fe (6.02MeV and 7.63MeV) also (n,n'γ) prompt gamma signal (4.43MeV) of carbon. BGO detector has been used for gamma spectrum acquisition. These experimentations has been carried out for initial feasibility studies of detecting prompt gamma lines as a part of PGNAA technique based explosive detection system development. A detail description of experimental set up and procedure has been discussed in paper.

  3. Improved calculation of the prompt fission neutron spectrum from the spontaneous fission of /sup 252/Cf: Preliminary results

    International Nuclear Information System (INIS)

    An improved calculation is presented for the prompt fission neutron spectrum N(E) from the spontaneous fission of /sup 252/Cf. In this calculation the fission-spectrum model of Madland and Nix is used, but with several improvements leading to a physically more accurate representation of the spectrum. Specifically, the contributions to N(E) from the entire fission-fragment mass and charge distributions will be calculated instead of calculating on the basis of a seven- point approximation to the peaks of these distributions as has been done in the past. Therefore, values of the energy release in fission, fission-fragment kinetic energy, and compound nucleus cross section for the inverse process will be considered on a point-by-point basis over the fragment yield distributions instead of considering averages of these quantities over the peaks of the distributions. Preliminary results will be presented and compared with a measurement, an earlier calculation, and a recent evaluation of the spectrum. 14 refs., 4 figs

  4. Prompt gamma neutron activation analysis of toxic elements in radioactive waste packages.

    Science.gov (United States)

    Ma, J-L; Carasco, C; Perot, B; Mauerhofer, E; Kettler, J; Havenith, A

    2012-07-01

    The French Alternative Energies and Atomic Energy Commission (CEA) and National Radioactive Waste Management Agency (ANDRA) are conducting an R&D program to improve the characterization of long-lived and medium activity (LL-MA) radioactive waste packages. In particular, the amount of toxic elements present in radioactive waste packages must be assessed before they can be accepted in repository facilities in order to avoid pollution of underground water reserves. To this aim, the Nuclear Measurement Laboratory of CEA-Cadarache has started to study the performances of Prompt Gamma Neutron Activation Analysis (PGNAA) for elements showing large capture cross sections such as mercury, cadmium, boron, and chromium. This paper reports a comparison between Monte Carlo calculations performed with the MCNPX computer code using the ENDF/B-VII.0 library and experimental gamma rays measured in the REGAIN PGNAA cell with small samples of nickel, lead, cadmium, arsenic, antimony, chromium, magnesium, zinc, boron, and lithium to verify the validity of a numerical model and gamma-ray production data. The measurement of a ∼20kg test sample of concrete containing toxic elements has also been performed, in collaboration with Forschungszentrum Jülich, to validate the model in view of future performance studies for dense and large LL-MA waste packages. PMID:22406218

  5. Treatability study using prompt gamma neutron activation analysis (PGNAA) technology, Phase I. Topical report

    Energy Technology Data Exchange (ETDEWEB)

    Congedo, T.V.; Dulloo, A.R.; Ruddy, F.H. [and others

    1995-06-01

    This report reviews the progress accomplished during Phase I of a two-phase project intended to demonstrate the use of Prompt Gamma Neutron Activation Analysis (PGNAA) as a technology for the characterization of hazardous and radioactive contaminants in concrete floors. A comprehensive experimental program was undertaken using the N-SCAN{trademark} PGNAA system, which was initially developed by Westinghouse for soil characterization, to determine the sensitivity of PGNAA for several contaminants in concrete. The experiments were performed in a test facility specially designed and constructed for this project. The lower limits of detection derived from the experimental data were encouraging for mercury, cadmium, uranium-238, thorium-232, technetium-99, chlorine, uranium-235 and chromium. These limits were achieved after modifications made to the original N-SCAN system significantly improved its sensitivity for elements located at or near the surface of concrete. With the implementation of additional performance-enhancing modifications scheduled in Phase II, the detection sensitivity of N-SCAN at the end of this project is expected to be at least one order of magnitude higher, allowing N-SCAN to become an effective characterization tool. N-SCAN has several important advantages over current characterization methods and technologies.

  6. Plutonium waste crib logging using the prompt fission neutron uranium logging system

    International Nuclear Information System (INIS)

    Sandia Laboratories' Uranium Logging Project has demonstrated their prompt fission neutron (PFN) logging system at the Hanford, WA, site for Rockwell-Hanford Operations (RHO). The dates of the demonstration were July 31 through August 2, 1979. The purpose was to show RHO the capabilities of the system for measuring plutonium concentration. An underground effluent disposal crib associated with their processing facilities was used as the test site. The performance criterion was to be able to detect a 10 nCi/g concentration of plutonium. Six test wells penetrating the crib were logged, as were three other wells. The PFN tool was able to maintain a good signal-to-noise ratio even under the most extreme conditions of high count rate and high background. The wells at the center of the crib indicated very high concentrations of plutonium, while those at the periphery indicated much less. Concentrations estimated to be lower than 10 nCi/g were detected. Comparisons with core data were not made. The technique used to obtain physical samples for analysis did not follow uranium-exploration coring practice so comparisons were not possible. The data interpretation model used was originally developed for uranium and was modified to calculate plutonium concentration. Results indicated that the operation of a PFN logging system by RHO personnel would provide a suitable technique for monitoring transuranic waste storage sites

  7. The relationship between the ratio of delayed-prompt neutrons and the multiplication factor of a uranium pit

    International Nuclear Information System (INIS)

    Uranium pit attribute detection is an important subject in the research of arms control and verification technology. 235U and 238U which are the main isotopes of uranium having weak spontaneously γ-radioactivity, and the 235U characteristic γ-rays are of lower energy, hence the difficulty of detecting and verifying a uranium pit attribute using passive detection technique. In this paper, we explore the method to derive the multiplication factor by analyzing the intensity relationship between delayed and prompt neutron which are released from uranium pit excited by high-energy photons and outer neutron. Some reactions such as (γ, n) and (γ, 2n) occur when the uranium material is excited by high-energy photons and the neutron emitted uranium nuclides will further induce uranium fission, while the outer neutron will cause scattering and induced fission. Approximation formulas about the radio of delayed-prompt neutron and the multiplication factor in different measuring conditions are obtained by analyzing the transport process, and accuracy of the formulas based on the numerical simulations is verified. (authors)

  8. Prompt γ-rays from the Fast Neutron Induced Fission on 235,238U and 232Th

    Science.gov (United States)

    Lebois, M.; Wilson, J. N.; Halipré, P.; Leniau, B.; Matea, I.; Oberstedt, A.; Oberstedt, S.; Verney, D.

    Preliminary results from the first experiment using the LICORNE neutron source at the IPN Orsay are presented. Prompt fission gamma rays from fast-neutron induced fission of 238U, 232Th and 235U were detected. Thick samples of around 50 g of 238U and 232Th are used for the first part of the experiment. An ionisation chamber containing ∼ 10 mg samples of 238U and 235U to provide a fission trigger is used for the second part of the experiment. Gamma rays have been detected using 17 high efficiency BaF2 detectors and 6 LaBr3 scintillator detectors.

  9. Development of a database for prompt gamma-ray neutron activation analysis: Summary report of the third research coordination meeting

    Energy Technology Data Exchange (ETDEWEB)

    Lindstrom, Richard M.; Firestone, Richard B.; Pavi, ???

    2003-04-01

    The main discussions and conclusions from the Third Co-ordination Meeting on the Development of a Database for Prompt Gamma-ray Neutron Activation Analysis are summarized in this report. All results were reviewed in detail, and the final version of the TECDOC and the corresponding software were agreed upon and approved for preparation. Actions were formulated with the aim of completing the final version of the TECDOC and associated software by May 2003.

  10. T-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Danilyan, G. V. [Institute for Theoretical and Experimental Physics (Russian Federation); Klenke, J. [Forschungs-Neutronenquelle Heinz Meier-Leibnitz (FRM II) (Germany); Krakhotin, V. A.; Kopach, Yu. N.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B. [Institute for Theoretical and Experimental Physics (Russian Federation)

    2011-05-15

    Study of the T-odd three-vector correlation in the emission of prompt neutrons from {sup 235}U fission by polarized cold neutrons has been continued at the facility MEPHISTO of the FRM II reactor (Technical University of Munich). The sought correlation was not found within experimental error of 2.3 Multiplication-Sign 10{sup -5}. The upper limit for the asymmetry coefficient has been set to vertical bar D{sub n} vertical bar < 6 Multiplication-Sign 10{sup -5} at 99% confidence level, whereas for ternary fission correlation coefficient D{sub {alpha}} = (170{+-}20) Multiplication-Sign 10{sup -5}. This limit casts doubt on a model that explains the three-vector correlation in ternary fission by the Coriolis mechanism. At the same time, five-vector correlation in the emission of prompt fission neutrons has been measured, which describes the rotation of the fissioning nucleus at the moment it breaks (ROT effect). At the angle 22.5 Degree-Sign to the fission axis, the correlation coefficient was found to be (1.57 {+-} 0.20) Multiplication-Sign 10{sup -4}, while at the angle of 67.5 Degree-Sign it is zero within the experimental uncertainty. The existence of ROT effect in the emission of prompt fission neutrons can be explained by the anisotropy of neutron emission in the rest frame of the fragment (fission fragments are aligned with respect to the axis of deformation of the fissioning nucleus), similar to the mechanism of ROT effect in the emission of prompt {gamma}-rays.

  11. Prompt gamma-ray neutron activation analysis methodology for determination of boron from trace to major contents

    International Nuclear Information System (INIS)

    Prompt gamma ray neutron activation analysis methodologies were standardized using a reflected neutron beam and Compton suppressed γ-ray spectrometer to quantify boron from trace to major concentrations. Neutron self-shielding correction factors for higher boron contents (0.2-10 mg) in samples were obtained from the sensitivity of chlorine by irradiating KCl with and without boron. This method was validated by determining boron concentrations in six boron compounds and applied to three borosilicate glass samples with boron contents in the range of 1-10 mg. Low concentrations of boron (10-58 mg kg-1) were also determined in two samples and five reference materials from NIST and IAEA. (author)

  12. Searches for T-odd correlations in the emission of prompt neutrons in the polarized-neutron-induced fission of 235U nuclei

    Science.gov (United States)

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2010-07-01

    The results of an experiment aimed at searches for formally T-odd correlations in the angular distribution of prompt neutrons from the fission of 235U nuclei are presented. The experiment was performed in the MEPHISTO polarized cold-neutron beam from the Munich FRMII reactor. The correlation coefficient proved to be (-3.5 ± 3.4) × 10-5 for a three-vector correlation (TRI effect) and (-5.0 ± 3.4) × 10-5 for a five-vector correlation (ROT effect). This means that no significant effects were discovered within the measurement errors. A comparison with the analogous effects in the ternary fission of 235U nuclei was performed. The values of the corresponding correlations in the angular distribution of prompt fission gamma rays were refined.

  13. Verification of threshold activation detection (TAD) technique in prompt fission neutron detection using scintillators containing 19F

    International Nuclear Information System (INIS)

    In the present study ⌀ 5''× 3'' and ⌀ 2''× 2'' EJ-313 liquid fluorocarbon as well as ⌀ 2'' × 3'' BaF2 scintillators were exposed to neutrons from a 252Cf neutron source and a Sodern Genie 16GT deuterium-tritium (D+T) neutron generator. The scintillators responses to β− particles with maximum endpoint energy of 10.4 MeV from the n+19F reactions were studied. Response of a ⌀ 5'' × 3'' BC-408 plastic scintillator was also studied as a reference. The β− particles are the products of interaction of fast neutrons with 19F which is a component of the EJ-313 and BaF2 scintillators. The method of fast neutron detection via fluorine activation is already known as Threshold Activation Detection (TAD) and was proposed for photofission prompt neutron detection from fissionable and Special Nuclear Materials (SNM) in the field of Homeland Security and Border Monitoring. Measurements of the number of counts between 6.0 and 10.5 MeV with a 252Cf source showed that the relative neutron detection efficiency ratio, defined as εBaF2 / εEJ−313−5'', is 32.0% ± 2.3% and 44.6% ± 3.4% for front-on and side-on orientation of the BaF2, respectively. Moreover, the ⌀ 5'' EJ-313 and side-on oriented BaF2 were also exposed to neutrons from the D+T neutron generator, and the relative efficiency εBaF2 / εEJ−313−5'' was estimated to be 39.3%. Measurements of prompt photofission neutrons with the BaF2 detector by means of data acquisition after irradiation (out-of-beam) of nuclear material and between the beam pulses (beam-off) techniques were also conducted on the 9 MeV LINAC of the SAPHIR facility

  14. Prompt-gamma neutron activation analysis for the non-destructive characterization of radioactive wastes; Prompt-Gamma-Neutronen-Aktivierungs-Analyse zur zerstoerungsfreien Charakterisierung radioaktiver Abfaelle

    Energy Technology Data Exchange (ETDEWEB)

    Kettler, John Paul Hermann

    2010-07-01

    In Germany, stringent official regulations govern the handling and final storage of radioactive waste. For this reason, the Federal Government has opted for final storage of radioactive waste with negligible heat generation in deep geological formations. At present the Konrad mine in Salzgitter will be rebuilt as a final disposal, the start of operation is scheduled for 2014. Radioactive waste with negligible heat generation originates from the operation and decommissioning of nuclear power plants, the medical sector or from research establishments. The requirements of the planning approval decision to build up the disposal Konrad, published on the 22{sup nd} of May 2002, obligate the waste producer to consider the limits for chemotoxic substances and to document the waste content. Before the radioactive waste can be stored in the final disposal, it is necessary to characterize the waste composition, relating to the concentration of water polluting substances. In particular for the wastes produced in the year before 1990, the so-called old wastes, there is a lack of documentation. The chemotoxicity of old wastes can mostly only characterized by time consuming and destructive methods. Furthermore these methods produce high costs, which depend on the arrangements to avoid contamination, to comply with the radiation protection and for the conditioning of the wastes. A prototype system, based on the Prompt-Gamma-Neutron-Activation-Analysis (PGNAA) with 14 MeV neutrons, has been developed in this work. This system allows the characterization of large samples, like 25 and 50 l drums. The signature of the element composition is in this processed by gamma-ray spectroscopy. This work was focused, in addition to the feasibility of the system, to the neutron and photon transport in large samples. Therefore the neutron and photon self-absorption in dependence of the sample composition were the main part of interest. Computer simulations (MCNP) and experiments were performed to

  15. Calculation and consideration of the experimental correction factor of the prompt k{sub o}-factors for the development of the PGNAA database[Prompt Gamma Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sun, K. M.; Choi, H. D. [Seoul National Univ., Seoul (Korea, Republic of)

    1999-10-01

    The prompt k{sub o}-factors are calculated for the light elements(A<45) with Cl comparator to develop a database for Prompt Gamma Neutron Activation Analysis(PGNAA). Calculations are performed by using the Lone table[8] and Firestone data[10], respectively, where both the absolute gamma intensities of the isotope and the element are used. The quality of the Firestone data is checked by comparing the Q-value of (n,{gamma}) reaction with the absolute gamma intensities and gamma energies. For the experimental determination of the prompt k{sub o}-factor, correction factor is derived for the case of the incident neutron spectrum containing epithermal component. For non-1/v absorbers, the correction factor is discussed in terms of the Westcott g-factors of the standard and comparator isotopes. Finally, the correction factor is derived for the polychromatic neutron beam of the PGNAA system in HANARO.

  16. Time-Off-Flight method for neutron rejection in prompt gamma imaging of beam range and density changes in proton therapy

    NARCIS (Netherlands)

    Biegun, Aleksandra; Cambraia Lopes, P.; Rinaldi, I.; Oxley, D.C.; Seravalli, E.; Verhaegen, F.; Dendooven, Peter; Parodi, K.; Schaart, D.R.; Crespo, P.

    2012-01-01

    A therapeutic proton beam penetrating a patient generates a large number of prompt photons as well as neutrons, resulting from proton-induced nuclear reactions. This allows for obtaining longitudinal beam-profile images via the detection of selected prompt-gamma rays emitted perpendicularly to the b

  17. Analysis of sewage sludge using an experimental prompt gamma neutron activation analysis (pgnaa) set-up with an am-be source

    Science.gov (United States)

    Idiri, Z.; Redjem, F.; Beloudah, N.

    2016-09-01

    An experimental PGNAA set-up using a 1 Ci Am-Be source has been developed and used for analysis of bulk sewage sludge samples issued from a wastewater treatment plant situated in an industrial area of Algiers. The sample dimensions were optimized using thermal neutron flux calculations carried out with the MCNP5 Monte Carlo Code. A methodology is then proposed to perform quantitative analysis using the absolute method. For this, average thermal neutron flux inside the sludge samples is deduced using average thermal neutron flux in reference water samples and thermal flux measurements with the aid of a 3He neutron detector. The average absolute gamma detection efficiency is determined using the prompt gammas emitted by chlorine dissolved in a water sample. The gamma detection efficiency is normalized for sludge samples using gamma attenuation factors calculated with the MCNP5 code for water and sludge. Wet and dehydrated sludge samples were analyzed. Nutritive elements (Ca, N, P, K) and heavy metals elements like Cr and Mn were determined. For some elements, the PGNAA values were compared to those obtained using Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma (ICP) methods. Good agreement is observed between the different values. Heavy element concentrations are very high compared to normal values; this is related to the fact that the wastewater treatment plant is treating not only domestic but also industrial wastewater that is probably rejected by industries without removal of pollutant elements. The detection limits for almost all elements of interest are sufficiently low for the method to be well suited for such analysis.

  18. Estimation of Covariances on Prompt Fission Neutron Spectra and Impact of the PFNS Model on the Vessel Fluence

    Directory of Open Access Journals (Sweden)

    Berge Léonie

    2016-01-01

    Full Text Available As the need for precise handling of nuclear data covariances grows ever stronger, no information about covariances of prompt fission neutron spectra (PFNS are available in the evaluated library JEFF-3.2, although present in ENDF/B-VII.1 and JENDL-4.0 libraries for the main fissile isotopes. The aim of this work is to provide an estimation of covariance matrices related to PFNS, in the frame of some commonly used models for the evaluated files, such as the Maxwellian spectrum, the Watt spectrum, or the Madland-Nix spectrum. The evaluation of PFNS through these models involves an adjustment of model parameters to available experimental data, and the calculation of the spectrum variance-covariance matrix arising from experimental uncertainties. We present the results for thermal neutron induced fission of 235U. The systematic experimental uncertainties are propagated via the marginalization technique available in the CONRAD code. They are of great influence on the final covariance matrix, and therefore, on the spectrum uncertainty band width. In addition to this covariance estimation work, we have also investigated the importance on a reactor calculation of the fission spectrum model choice. A study of the vessel fluence depending on the PFNS model is presented. This is done through the propagation of neutrons emitted from a fission source in a simplified PWR using the TRIPOLI-4® code. This last study includes thermal fission spectra from the FIFRELIN Monte-Carlo code dedicated to the simulation of prompt particles emission during fission.

  19. Estimation of Covariances on Prompt Fission Neutron Spectra and Impact of the PFNS Model on the Vessel Fluence

    Science.gov (United States)

    Berge, Léonie; Litaize, Olivier; Serot, Olivier; Archier, Pascal; De Saint Jean, Cyrille; Pénéliau, Yannick; Regnier, David

    2016-02-01

    As the need for precise handling of nuclear data covariances grows ever stronger, no information about covariances of prompt fission neutron spectra (PFNS) are available in the evaluated library JEFF-3.2, although present in ENDF/B-VII.1 and JENDL-4.0 libraries for the main fissile isotopes. The aim of this work is to provide an estimation of covariance matrices related to PFNS, in the frame of some commonly used models for the evaluated files, such as the Maxwellian spectrum, the Watt spectrum, or the Madland-Nix spectrum. The evaluation of PFNS through these models involves an adjustment of model parameters to available experimental data, and the calculation of the spectrum variance-covariance matrix arising from experimental uncertainties. We present the results for thermal neutron induced fission of 235U. The systematic experimental uncertainties are propagated via the marginalization technique available in the CONRAD code. They are of great influence on the final covariance matrix, and therefore, on the spectrum uncertainty band width. In addition to this covariance estimation work, we have also investigated the importance on a reactor calculation of the fission spectrum model choice. A study of the vessel fluence depending on the PFNS model is presented. This is done through the propagation of neutrons emitted from a fission source in a simplified PWR using the TRIPOLI-4® code. This last study includes thermal fission spectra from the FIFRELIN Monte-Carlo code dedicated to the simulation of prompt particles emission during fission.

  20. Development of a database for prompt γ-ray neutron activation analysis. Summary report of the first research coordination meeting

    International Nuclear Information System (INIS)

    This report summarizes the presentations, recommendations and conclusions of the First Research Co-ordination Meeting on Development of a Database for Prompt γ-ray Neutron Activation Analysis. Neutron-capture Prompt γ-ray Activation Analysis (PGAA) is a non-destructive radioanalytical method, capable of rapid or in-situ simultaneous multielement analysis of many elements of the Periodic Table, from hydrogen to uranium, in the same sample. Inaccuracy and incompleteness of the data available for use in PGAA are a significant handicap in the qualitative and quantitative analysis of capture-gamma spectra. The goal of this CRP is to replace the twenty-year-old data from a single laboratory with something fundamentally new: an evaluated database which includes a combination of evaluated nuclear physics data, physical theory, and recent measurements. The resulting database will be comparable in quality with that for radioactive decay. In addition, more accurate values of neutron capture cross-sections and γ-ray intensities that result from this database will improve the accuracy of radiation shielding calculations. (author)

  1. Study of U235 neutron fission spectrum by the knowledge of cross sections average over that spectrum

    International Nuclear Information System (INIS)

    A literature search of cross sections averaged over the fission neutron spectrum confirms inconsistencies between calculated and experimental values for high threshold reactions. Since, in this case, calculated averaged cross sections are systematically lower than measured values, it is concluded that the representations used to carry out these calculations underestimate the number of neutrons in the high energy region of the spectrum. A careful measurement of the averaged cross section for the 45Sc(n,2n) 44gSc and 45Sc(n,2n) 44mSc high threshold reactions had been performed in the RA-6 Neutron Activation Analysis Laboratory after carefully checking that the neutron flux at the core position where the samples were being irradiated was indeed an undisturbed fission spectrum. The experimental values are greater than those calculated with either, Watt type representations or the one based on the Madland and Nix model for the prompt fission spectrum. In many areas of nuclear engineering, like validation of nuclear data, reactor calculations, applied nuclear physics, shielding design, etc., it is of great practical importance to have a representation for the neutron flux that can be expressed in a closed analytical form and that agrees with experimental results, specially for the most widely fissile nuclide, 235U. The results of the calculations mentioned above lead us to propose an analytical form for the 235U fission neutron spectrum that better agrees with experimental results in the whole energy spectrum. We propose two different forms; both are a modification of the Watt-type form that has been adopted within the ENDF/B-V files. One of the new analytical representations is defined in two regions: below 9.5 MeV it is exactly the same formula as that used within the ENDF/B-V files, above this energy the parameters of this formula are changed. The other proposed analytical representation is expressed by a single formula in the whole energy range. These two new

  2. Borehole prompt gamma neutron activation and comparison with Monte Carlo simulation using MCNP code Borehole PGNAA experiment comparison with MCNP

    Energy Technology Data Exchange (ETDEWEB)

    Sohrabpour, M. [Gamma Irradiation Center, Atomic Energy Organization of Iran, Tehran (Iran, Islamic Republic of); Shahriari, M. [Physics Department, Amir Kabir University of Technology, Tehran (Iran, Islamic Republic of); Zarifian, V.; Moghadam, K.K. [Nuclear Research Center, Atomic Energy Organization of Iran, Tehran (Iran, Islamic Republic of)

    1999-04-01

    A borehole experiment using prompt gamma neutron activation analysis has been performed in a large sample box having a volume of 1 m{sup 3}. Brine solutions having a salt concentration in the range of 0-10 wt% of sodium chloride has been used. Chlorine prompt gamma spectral response as a function of the salt concentrations have been obtained. A simulation of the above experiments has also been carried out using the MCNP4A Monte Carlo code. Comparison of the experimental spectral response versus the simulated MCNP4A data has produced excellent agreement. In view of the good benchmark data it is proposed that due to the inherent problems associated with the ordinary calibration procedures for the borehole logging tools, one could employ a combined calibration/simulation scheme to circumvent these difficulties and achieve more effective results.

  3. In-vivo measurement of kidney and liver cadmium by neutron capture prompt gamma-ray analysis

    International Nuclear Information System (INIS)

    A method for the determination of Cd in-vivo in human kidney and liver has been developed. The technique employs the detection of prompt gamma-rays emitted under slow neutron capture in Cd. The method allows measurement of absolute quantities of Cd in the left kidney and Cd concentration in the liver, in normal population. The limit of detection of cadmium is 2.5 mg for the left kidney and 1.5 μg/g (wet weight) for the liver, for a localized dose of 670 mrem

  4. Basic Study of Defective Ammunition Detection by the Combination of PGNAA (Prompt Gamma-ray Neutron Activation Analysis) and Chemometrics

    Energy Technology Data Exchange (ETDEWEB)

    Im, Hee Jung; Song, Byoung Chul; Shin, Jae Kon; Park, Yong Joon; Song, Kyu Seok

    2010-01-15

    We are interested in evaluating detection capability of defective ammunition in store for years even decades by using prompt gamma-ray neutron activation analysis (PGNAA) method. The PGNAA method can be used for multielemental analysis of ammunition to check the inner elemental composition changes. At first, in this study, instead of the real experimental gamma spectrum data from PGNAA, the gamma spectrum data from MCNP transport code simulation were obtained to observe discriminant classes for defective ammunition by adding 10% moisture. For this, the collected MCNP data were applied to principal component analysis (PCA) for the effective pattern recognition.

  5. The Prompt Fission Neutron Spectrum: From Experiment to the Evaluated Data and its Impact on Critical Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Rising, Michael Evan [Los Alamos National Laboratory

    2015-06-10

    After a brief introduction concerning nuclear data, prompt fission neutron spectrum (PFNS) evaluations and the limited PFNS covariance data in the ENDF/B-VII library, and the important fact that cross section uncertainties ~ PFNS uncertainties, the author presents background information on the PFNS (experimental data, theoretical models, data evaluation, uncertainty quantification) and discusses the impact on certain well-known critical assemblies with regard to integral quantities, sensitivity analysis, and uncertainty propagation. He sketches recent and ongoing research and concludes with some final thoughts.

  6. Neutron-induced fission: properties of prompt neutron and γ rays as a function of incident energy

    Science.gov (United States)

    Stetcu, I.; Talou, P.; Kawano, T.

    2016-06-01

    We have applied the Hauser-Feshbach statistical theory, in a Monte-Carlo implementation, to the de-excitation of fission fragments, obtaining a reasonable description of the characteristics of neutrons and gamma rays emitted before beta decays toward stability. Originally implemented for the spontaneous fission of 252Cf and the neutroninduced fission of 235U and 239Pu at thermal neutron energy, in this contribution we discuss the extension of the formalism to incident neutron energies up to 20 MeV. For the emission of pre-fission neutrons, at incident energies beyond second-chance fission, we take into account both the pre-equilibrium and statistical pre-fission components. Phenomenological parameterizations of mass, charge and TKE yields are used to obtain the initial conditions for the fission fragments that subsequently decay via neutron and emissions. We illustrate this approach for 239Pu(n,f).

  7. Design of Stopper of Prompt Gamma Neutron Activation Analysis Facility at China Advanced Research Reactor

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The PGNAA facility consists of the filtered collimated neutron beam, the shielding of the whole facility, the control system, the detecting equipment and the data acquisition and analysis system. The neutron beam is filtered by a mono-crystalline bismuth filter,

  8. Effect of the fragment excitation energy distribution on the prompt fission neutron spectrum

    International Nuclear Information System (INIS)

    The effects of cascade emission of neutrons from a nucleus and of distribution of the initial excitation energy upon characteristics of the emission spectrum are studied. Calculations of the emission spectrum are made in the Weisskopf form in the constant temperature approximation. It has been elucidated that the cascade character of particle emission is not sufficient for the total spectrum to approach the maxwellian one. A dependence of the distorting function upon energy has been obtained. The calculation spectrum is compared with the experimental and with the Weisskopf spectra. A conclusion is drawn that the temperature dependence upon excitation energy is predominant in formation of a fission neutron spectrum

  9. The Energies, Angular Distribution and Yields of the Prompt Neutrons from Individual Fragments in the Thermal-Neutron Fission of U233 and U235

    International Nuclear Information System (INIS)

    An apparatus for simultaneously recording the velocities of both fission fragments and the velocity of a neutron at any one of four angles to the fragment direction has been used to investigate the neutron-emission properties of individual fragments. Early results for U233 exhibit the saw-tooth variation of v, the neutron yield per fragment, observed in the spontaneous fission of Cf252 The yields in the vicinity of mass 130 are consistent with no neutrons being emitted from these fragments. Unlike the neutron yields, the average neutron kinetic energy is symmetric about the symmetric mass point, being high near this point and low at the most probable mass division. The paradox between very small yields and high apparent nuclear temperatures has been qualitatively explained on the basis of a model that takes account of shell structure in the level densities and assumes that at the time of scission the fragments are cold but in some cases highly deformed, in others nearly spherical. The model is supported by the fact that in fissions with more than the average total excitation energy, the fragments near mass 130 and 80 receive much less than half the increase in energy and the other fragment of the pair much more. The experiment is now being conducted with U235 under considerably improved conditions. The background per channel under the neutron spectrum has been reduced by nearly a factor of three, so that 0.39 of all recorded events in the 10° detector are useful neutron events with a corresponding increase in statistical accuracy. Better time resolution in the fragment system (1.5 ns, full width at half maximum) has allowed the. flight paths to be shortened to 125 and 100 cm (formerly 145-145 cm) with a concomitant higher countings rate. (author)

  10. Thoughts on Sensitivity Analysis and Uncertainty Propagation Methods with Respect to the Prompt Fission Neutron Spectrum Impact on Critical Assemblies

    International Nuclear Information System (INIS)

    The prompt fission neutron spectrum (PFNS) uncertainties in the n+239Pu fission reaction are used to study the impact on several fast critical assemblies modeled in the MCNP6.1 code. The newly developed sensitivity capability in MCNP6.1 is used to compute the keff sensitivity coefficients with respect to the PFNS. In comparison, the covariance matrix given in the ENDF/B-VII.1 library is decomposed and randomly sampled realizations of the PFNS are propagated through the criticality calculation, preserving the PFNS covariance matrix. The information gathered from both approaches, including the overall keff uncertainty, is statistically analyzed. Overall, the forward and backward approaches agree as expected. The results from a new method appear to be limited by the process used to evaluate the PFNS and is not necessarily a flaw of the method itself. Final thoughts and directions for future work are suggested

  11. What Do s- and p-Wave Neutron Average Radiative Widths Reveal

    Energy Technology Data Exchange (ETDEWEB)

    Mughabghab, S.F.

    2010-04-30

    A first observation of two resonance-like structures at mass numbers 92 and 112 in the average capture widths of the p-wave neutron resonances relative to the s-wave component is interpreted in terms of a spin-orbit splitting of the 3p single-particle state into P{sub 3/2} and P{sub 1/2} components at the neutron separation energy. A third structure at about A = 124, which is not correlated with the 3p-wave neutron strength function, is possibly due to the Pygmy Dipole Resonance. Five significant results emerge from this investigation: (i) The strength of the spin-orbit potential of the optical-model is determined as 5.7 {+-} 0.5 MeV, (ii) Non-statistical effects dominate the p-wave neutron-capture in the mass region A = 85 - 130, (iii) The background magnitude of the p-wave average capture-width relative to that of the s-wave is determined as 0.50 {+-} 0.05, which is accounted for quantitatively in tenns of the generalized Fermi liquid model of Mughabghab and Dunford, (iv) The p-wave resonances arc partially decoupled from the giant-dipole resonance (GDR), and (v) Gamma-ray transitions, enhanced over the predictions of the GDR, are observed in the {sup 90}Zr - {sup 98}Mo and Sn-Ba regions.

  12. Optimization of combined delayed neutron and differential die-away prompt neutron signal detection for characterization of spent nuclear fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Blanc, Pauline [Los Alamos National Laboratory; Tobin, Stephen J [Los Alamos National Laboratory; Croft, Stephen [Los Alamos National Laboratory; Menlove, Howard O [Los Alamos National Laboratory; Swinhoe, M [Los Alamos National Laboratory; Lee, T [NON LANL

    2010-12-02

    The Next Generation Safeguards Initiative (NGSI) of the U.S. Department of Energy (DOE) has funded multiple laboratories and universities to develop a means to accurately quantify the Plutonium (Pu) mass in spent nuclear fuel assemblies and ways to also detect potential diversion of fuel pins. Delayed Neutron (DN) counting provides a signature somewhat more sensitive to {sup 235}U than Pu while Differential Die-Away (DDA) is complementary in that it has greater sensitivity to Pu. The two methods can, with care, be combined into a single instrument which also provides passive neutron information. Individually the techniques cannot robustly quantify the Pu content but coupled together the information content in the signatures enables Pu quantification separate to the total fissile content. The challenge of merging DN and DDA, prompt neutron (PN) signal, capabilities in the same design is the focus of this paper. Other possibilities also suggest themselves, such as a direct measurement of the reactivity (multiplication) by either the boost in signal obtained during the active interrogation itself or by the extension of the die-away profile. In an early study, conceptual designs have been modeled using a neutron detector comprising fission chambers or 3He proportional counters and a {approx}14 MeV neutron Deuterium-Tritium (DT) generator as the interrogation source. Modeling was performed using the radiation transport code Monte Carlo N-Particles eXtended (MCNPX). Building on this foundation, the present paper quantifies the capability of a new design using an array of {sup 3}He detectors together with fission chambers to optimize both DN and PN detections and active characterization, respectively. This new design was created in order to minimize fission in {sup 238}U (a nuisance DN emitter), to use a realistic neutron generator, to reduce the cost and to achieve near spatial interrogation and detection of the DN and PN, important for detection of diversion, all within

  13. Analysis of prompt fission neutron spectrum and multiplicity for 237Np(n,f)in the frame of multi-modal Los Alamos model

    Institute of Scientific and Technical Information of China (English)

    Zheng Na; Ding Yi; Zhong Chun-Lai; Chen Jin-Xiang; Fan Tie-Shuan

    2009-01-01

    The improved version of Los Alamos model with the multi-modal fission approach is used to analyse the prompt fission neutron spectrum and multiplicity for the neutron-induced fission of 237Np.The spectra of I~eutrons emitted from fragments for the three most dominant fission modes(standard Ⅰ,standard Ⅱ and superlong)are calculated separately and the total spectrum is synthesized.The multi-modal parameters contained in the spectrum model are determined on the basis of experimental data of fission fragment mass distributions.The calculated total prompt fission neutron spectrum and multiplicity are better agreement with the experimental data than those obtained from the conventional treatment of the Los Alamos model.

  14. Measurement of prompt neutrons from fission fragments for {sup 235}U(n{sub th}, f)

    Energy Technology Data Exchange (ETDEWEB)

    Nishio, Katsuhisa; Yamamoto, Hideki; Jinno, Ikuo; Kimura, Itsuro; Nakagome, Yoshihiro [Kyoto Univ. (Japan)

    1997-03-01

    When the level density parameter is obtained from neutron resonance experiment and so forth, its value depends upon its model. In particular, the value forms 1.5 times difference by if the level increase due to collective motion is considered or not. The measuring method shown in this report has a characteristics capable of obtain an absolute value of the level density parameter. Then, in this paper, a consideration using Iljinov`s empirical equation on shell effect and collective motion of the fission fragment was conducted and a investigation on shell effect and collective motion of the fission fragment was executed. as a result, the level density parameter of the fission fragment obtained by the {sup 235}U(n{sub th},f) showed a distribution of a sawtooth wave shape, which is resemble to that of {sup 252}Cf(sf). And, it was found that this distribution can be explained by an empirical equation considering shell effect of fission fragment dependency and collective motion, and so forth. (G.K.)

  15. Neutron Damage in Mechanically-Cooled High-Purity Germanium Detectors for Field-Portable Prompt Gamma Neutron Activation Analysis (PGNAA) Systems

    Energy Technology Data Exchange (ETDEWEB)

    E.H. Seabury; C.J. Wharton; A.J. Caffrey; J.B. McCabe; C. DeW. Van Siclen

    2013-10-01

    Prompt Gamma Neutron Activation (PGNAA) systems require the use of a gamma-ray spectrometer to record the gamma-ray spectrum of an object under test and allow the determination of the object’s composition. Field-portable systems, such as Idaho National Laboratory’s PINS system, have used standard liquid-nitrogen-cooled high-purity germanium (HPGe) detectors to perform this function. These detectors have performed very well in the past, but the requirement of liquid-nitrogen cooling limits their use to areas where liquid nitrogen is readily available or produced on-site. Also, having a relatively large volume of liquid nitrogen close to the detector can impact some assessments, possibly leading to a false detection of explosives or other nitrogen-containing chemical. Use of a mechanically-cooled HPGe detector is therefore very attractive for PGNAA applications where nitrogen detection is critical or where liquid-nitrogen logistics are problematic. Mechanically-cooled HPGe detectors constructed from p-type germanium, such as Ortec’s trans-SPEC, have been commercially available for several years. In order to assess whether these detectors would be suitable for use in a fielded PGNAA system, Idaho National Laboratory (INL) has been performing a number of tests of the resistance of mechanically-cooled HPGe detectors to neutron damage. These detectors have been standard commercially-available p-type HPGe detectors as well as prototype n-type HPGe detectors. These tests compare the performance of these different detector types as a function of crystal temperature and incident neutron fluence on the crystal.

  16. Energy-averaged neutron cross sections of fast-reactor structural materials

    International Nuclear Information System (INIS)

    The status of energy-averaged cross sections of fast-reactor structural materials is outlined with emphasis on U.S. data programs in the neutron-energy range 1-10 MeV. Areas of outstanding accomplishment and significant uncertainty are noted with recommendations for future efforts. Attention is primarily given to the main constituents of stainless steel (e.g., Fe, Ni, and Cr) and, secondarily, to alternate structural materials (e.g., V, Ti, Nb, Mo, Zr). Generally, the mass regions of interest are A approximately 50 to 60 and A approximately 90 to 100. Neutron total and elastic-scattering cross sections are discussed with the implication on the non-elastic-cross sections. Cross sections governing discrete-inelastic-neutron-energy transfers are examined in detail. Cross sections for the reactions (n;p), (n;n',p), (n;α), (n;n',α) and (n;2n') are reviewed in the context of fast-reactor performance and/or diagnostics. The primary orientation of the discussion is experimental with some additional attention to the applications of theory, the problems of evaluation and the data sensitivity of representative fast-reactor systems

  17. Performance test results of noninvasive characterization of Resource Conservation and Recovery Act surrogate waste by prompt gamma neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Gehrke, R.J.; Streier, G.G.

    1997-03-01

    During FY-96, a performance test was carried out with funding from the Mixed Waste Focus Area (MWFA) of the Department of Energy (DOE) to determine the noninvasive elemental assay capabilities of commercial companies for Resource Conservation and Recovery Act (RCRA) metals present in 8-gal drums containing surrogate waste. Commercial companies were required to be experienced in the use of prompt gamma neutron activation analysis (PGNAA) techniques and to have a prototype assay system with which to conduct the test assays. Potential participants were identified through responses to a call for proposals advertised in the Commerce Business Daily and through personal contacts. Six companies were originally identified. Two of these six were willing and able to participate in the performance test, as described in the test plan, with some subsidizing from the DOE MWFA. The tests were conducted with surrogate sludge waste because (1) a large volume of this type of waste awaits final disposition and (2) sludge tends to be somewhat homogeneous. The surrogate concentrations of the above RCRA metals ranged from {approximately} 300 ppm to {approximately} 20,000 ppm. The lower limit was chosen as an estimate of the expected sensitivity of detection required by noninvasive, pretreatment elemental assay systems to be of value for operational and compliance purposes and to still be achievable with state-of-the-art methods of analysis. The upper limit of {approximately} 20,000 ppm was chosen because it is the opinion of the author that assay above this concentration level is within current state-of-the-art methods for most RCRA constituents. This report is organized into three parts: Part 1, Test Plan to Evaluate the Technical Status of Noninvasive Elemental Assay Techniques for Hazardous Waste; Part 2, Participants` Results; and Part 3, Evaluation of and Comments on Participants` Results.

  18. Measurement of 248cm/252Cf Spontaneous Prompt Fission Neutron Spectrum%248 Cm和252Cf自发裂变瞬发中子谱测量

    Institute of Scientific and Technical Information of China (English)

    包尚联; 刘文龙; 温琛林; 樊铁栓; 巴登柯夫; 马尧罗夫

    2001-01-01

    用飞行时间方法测量200keV-12MeV能区内248Cm和252Cf自发裂变瞬发中子谱,以国际原子能机构推荐的252Cf自发裂变瞬发中子谱为标准,可以免去探测器效率刻度的问题并消除系统误差,提高测量精度.实验用一个微型电离室作为裂变碎片探测器,两个芪晶体中子探测器测量中子及一套基于微机的CAMAC系统组成的飞行时间测量谱仪,在一个空旷的测量室内完成的.飞行距离分别为32,50和100cm,经过对数据的处理和分析给出了200keV-12MeV的中子能区内的实验数据.用Maxwell分布对实验数据进行拟合,得到的核温度为(1.401±0.006)MeV.%In order to treat the waste material of nuclear power and develop new type of clean nuclear power, it is necessary to measure the neutron data of long half life nuclei existed in the waste material. The prompt spontaneous neutron spectrum is one of the most important nuclear data for new type nuclear power facilities as well as for understanding the mechanism of fission neutron emission. The measurements of 248Cm/252Cf spontaneous prompt fission neutron spectrum in the neutron energy range from 200keV to 12MeV were performed by using TOF method. A micro-ionization chamber was used as fission fragment detector and stibene crystal as neutron detector. The flying paths of neutrons for the measurements were 30cm, 50cm and 100cm respectively. The spontaneous prompt fission neutron spectrum of 248Cm was fitted by the Maxwellian distribution and the temperature was determined as(1.401±0.006)MeV in the corresponding neutron energy range.

  19. Different approach to calculating average angular distributions of elastically scattered neutrons in the resonance region

    International Nuclear Information System (INIS)

    A relatively simple formalism for calculating the average neutron elastic angular distribution dσel/dΩ in the resonance region below several hundred keV is presented. The expression for dσel/dΩ depends mainly on the R-matrix parameters S0, R', S1, and R1∞. Comparisons between calculated and experimental angular distributions are presented for 103Rh, 139La, 232Th, and 238U. A fit to 238U data at 75 keV led to a value of the p-wave strength function of S1=1.81±0.35x10-4. Except for measuring a complete set of individual l=1 resonances, determining the p-wave strength function by fitting low-energy angular distributions is probably more reliable than, or competitive with, other techniques which are available. An analysis of elastic angular distributions as a function of neutron energy is also well suited to a search for intermediate structure in the s- or p-wave strength function. copyright 1997 The American Physical Society

  20. Average Neutron Total Cross Sections in the Unresolved Energy Range From ORELA High Resolutio Transmission Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Derrien, H

    2004-05-27

    Average values of the neutron total cross sections of {sup 233}U, {sup 235}U, {sup 238}U, and {sup 239}Pu have been obtained in the unresolved resonance energy range from high-resolution transmission measurements performed at ORELA in the past two decades. The cross sections were generated by correcting the effective total cross sections for the self-shielding effects due to the resonance structure of the data. The self-shielding factors were found by calculating the effective and true cross sections with the computer code SAMMY for the same Doppler and resolution conditions as for the transmission measurements, using an appropriate set of resonance parameters. Our results are compared to results of previous measurements and to the current ENDF/B-VI data.

  1. Development of a technique using MCNPX code for determination of nitrogen content of explosive materials using prompt gamma neutron activation analysis method

    Energy Technology Data Exchange (ETDEWEB)

    Nasrabadi, M.N., E-mail: mnnasrabadi@ast.ui.ac.ir [Department of Nuclear Engineering, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Bakhshi, F.; Jalali, M.; Mohammadi, A. [Department of Nuclear Engineering, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of)

    2011-12-11

    Nuclear-based explosive detection methods can detect explosives by identifying their elemental components, especially nitrogen. Thermal neutron capture reactions have been used for detecting prompt gamma 10.8 MeV following radioactive neutron capture by {sup 14}N nuclei. We aimed to study the feasibility of using field-portable prompt gamma neutron activation analysis (PGNAA) along with improved nuclear equipment to detect and identify explosives, illicit substances or landmines. A {sup 252}Cf radio-isotopic source was embedded in a cylinder made of high-density polyethylene (HDPE) and the cylinder was then placed in another cylindrical container filled with water. Measurements were performed on high nitrogen content compounds such as melamine (C{sub 3}H{sub 6}N{sub 6}). Melamine powder in a HDPE bottle was placed underneath the vessel containing water and the neutron source. Gamma rays were detected using two NaI(Tl) crystals. The results were simulated with MCNP4c code calculations. The theoretical calculations and experimental measurements were in good agreement indicating that this method can be used for detection of explosives and illicit drugs.

  2. Sample dependent response of a LaCl{sub 3}:Ce detector in prompt gamma neutron activation analysis of bulk hydrocarbon samples

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A., E-mail: aanaqvi@kfupm.edu.sa [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Al-Matouq, Faris A.; Khiari, F.Z. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Isab, A.A. [Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Khateeb-ur-Rehman,; Raashid, M. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)

    2013-08-11

    The response of a LaCl{sub 3}:Ce detector has been found to depend upon the hydrogen content of bulk samples in prompt gamma analysis using 14 MeV neutron inelastic scattering. The moderation of 14 MeV neutrons from hydrogen in the bulk sample produces thermal neutrons around the sample which ultimately excite chlorine capture gamma rays in the LaCl{sub 3}:Ce detector material. Interference of 6.11 MeV chlorine gamma rays from the detector itself with 6.13 MeV oxygen gamma rays from the bulk samples makes the intensity of the 6.13 MeV oxygen gamma ray peak relatively insensitive to variations in oxygen concentration. The strong dependence of the 1.95 MeV doublet chlorine gamma ray yield on hydrogen content of the bulk samples confirms fast neutron moderation from hydrogen in the bulk samples as a major source of production of thermal neutrons and chlorine gamma rays in the LaCl{sub 3}:Ce detector material. Despite their poor oxygen detection capabilities, these detectors have nonetheless excellent detection capabilities for hydrogen and carbon in benzene, butyl alcohol, propanol, propanic acid, and formic acid bulk samples using 14 MeV neutron inelastic scattering.

  3. The feasibility of in vivo quantification of bone-gadolinium in humans by prompt gamma neutron activation analysis (PGNAA) following gadolinium-based contrast-enhanced MRI

    Science.gov (United States)

    Mostafaei, F.; McNeill, F. E.; Chettle, D. R.; Noseworthy, M. D.; Prestwich, W. V.

    2015-11-01

    The feasibility of using a 238Pu/Be-based in vivo prompt γ-ray neutron activation analysis (IVNAA) system, previously successfully used for measurements of muscle, for the detection of gadolinium (Gd) in bone was presented. Gd is extensively used in contrast agents in MR imaging. We present phantom measurement data for the measurement of Gd in the tibia. Gd has seven naturally occurring isotopes, of which two have extremely large neutron capture cross sections; 155Gd (14.8% natural abundance (NA), σ= 60,900 barns) and 157Gd (15.65% NA, σ= 254,000 barns). Our previous work focused on muscle but this only informs about the short term kinetics of Gd. We studied the possibility of measuring bone, as it may be a long term storage site for Gd. A human simulating bone phantom set was developed. The phantoms were doped with seven concentrations of Gd of concentrations 0.0, 25, 50, 75, 100, 120 and 150 ppm. Additional elements important for neutron activation analysis, Na, Cl and Ca, were also included to create an overall elemental composition consistent with Reference Man. The overall conclusion is that the potential application of this Pu-Be-based prompt in vivo NAA for the monitoring of the storage and retention of Gd in bone is not feasible.

  4. Monte Carlo simulation of prompt gamma-ray spectra from depleted uranium under D-T neutron irradiation and electron recoil spectra in a liquid scintillator detector

    CERN Document Server

    Qin, Jianguo; Liu, Rong; Zhu, Tonghua; Zhang, Xinwei; Ye, Bangjiao

    2015-01-01

    To overcome the problem of inefficient computing time and unreliable results in MCNP5 calculation, a two-step method is adopted to calculate the energy deposition of prompt gamma-rays in detectors for depleted uranium spherical shells under D-T neutrons irradiation. In the first step, the gamma-ray spectrum for energy below 7 MeV is calculated by MCNP5 code; secondly, the electron recoil spectrum in a BC501A liquid scintillator detector is simulated based on EGSnrc Monte Carlo Code with the gamma-ray spectrum from the first step as input. The comparison of calculated results with experimental ones shows that the simulations agree well with experiment in the energy region 0.4-3 MeV for the prompt gamma-ray spectrum and below 4 MeVee for the electron recoil spectrum. The reliability of the two-step method in this work is validated.

  5. Monte Carlo simulation of prompt gamma-ray spectra from depleted uranium under D-T neutron irradiation and electron recoil spectra in a liquid scintillator detector

    OpenAIRE

    Qin, Jianguo; Lai, Caifeng; Liu, Rong; Zhu, Tonghua; Zhang, Xinwei; Ye, Bangjiao

    2015-01-01

    To overcome the problem of inefficient computing time and unreliable results in MCNP5 calculation, a two-step method is adopted to calculate the energy deposition of prompt gamma-rays in detectors for depleted uranium spherical shells under D-T neutrons irradiation. In the first step, the gamma-ray spectrum for energy below 7 MeV is calculated by MCNP5 code; secondly, the electron recoil spectrum in a BC501A liquid scintillator detector is simulated based on EGSnrc Monte Carlo Code with the g...

  6. Hydrogen content in doped and undoped BaPrO3 and BaCeO3 by cold neutron prompt-gamma activation analysis

    OpenAIRE

    Jones, Camille Y.; WU, Jian; Li, Liping; Haile, Sossina M.

    2005-01-01

    Proton uptake in undoped and Y-doped BaPrO3 has been measured by cold neutron prompt-gamma activation analysis, and compared to the proton uptake in Gd-doped BaCeO3, as determined by the same technique. The conventional proton incorporation model of perovskites in which oxygen ion vacancies, generated by the introduction of the trivalent dopant onto the tetravalent perovskite site, are filled with hydroxyl groups upon exposure of the sample to H2O containing atmospheres, predicts that the pro...

  7. Development of an experimental device based on the digitalization of the signal and dedicated to the characterization of fission fragments and prompt neutrons; Developpement d'un dispositif experimental base sur la digitalisation des signaux et dedie a la caracterisation des fragments de fission et des neutrons prompts emis

    Energy Technology Data Exchange (ETDEWEB)

    Varapai, N

    2006-12-15

    The present work demonstrates the application of the digital technique for nuclear measurements. This new technique is based on the digitalization of the signals from the detectors and has several advantages. This technique allows us to extract the maximum amount of information contained in the signal shape. In the case of an ionization chamber this signal contains the necessary information on the particle kinetic energy, emission angle and mass. This method has been implemented for measurements of promptly emitted fission neutrons in coincidence with fission fragments from {sup 252}Cf(sf). A double Frisch-grid ionization chamber is used as fission fragment detector. The promptly emitted neutrons are detected by a NE213 liquid scintillation detector. This work displays how delicate analysis of the digitalized signals permitted us to infer the mass and kinetic energy distributions of the fission fragments as well as the neutron energy spectrum and multiplicity. The outline of this thesis is as follows: Chapter 2 gives an overview of the experimental tools used in this work. Chapter 3 explains the analysis procedure of the digitalized anode signal from an ionization chamber. Chapter 4 gives a detailed explanation of the analysis procedure of the digitalized signal from a neutron detector. In Chapter 5 the analysis procedure of the fission fragment events in coincidence with neutrons is given.

  8. Intercomparison of inductively coupled plasma mass spectrometry, quantitative neutron capture radiography, and prompt gamma activation analysis for the determination of boron in biological samples

    International Nuclear Information System (INIS)

    Boron determination in blood and tissue samples is a crucial task especially for treatment planning, preclinical research, and clinical application of boron neutron capture therapy (BNCT). Comparison of clinical findings remains difficult due to a variety of analytical methods, protocols, and standard reference materials in use. This paper addresses the comparability of inductively coupled plasma mass spectrometry, quantitative neutron capture radiography, and prompt gamma activation analysis for the determination of boron in biological samples. It was possible to demonstrate that three different methods relying on three different principles of sample preparation and boron detection can be validated against each other and yield consistent results for both blood and tissue samples. The samples were obtained during a clinical study for the application of BNCT for liver malignancies and therefore represent a realistic situation for boron analysis. (orig.)

  9. Intercomparison of inductively coupled plasma mass spectrometry, quantitative neutron capture radiography, and prompt gamma activation analysis for the determination of boron in biological samples.

    Science.gov (United States)

    Schütz, C L; Brochhausen, C; Hampel, G; Iffland, D; Kuczewski, B; Otto, G; Schmitz, T; Stieghorst, C; Kratz, J V

    2012-10-01

    Boron determination in blood and tissue samples is a crucial task especially for treatment planning, preclinical research, and clinical application of boron neutron capture therapy (BNCT). Comparison of clinical findings remains difficult due to a variety of analytical methods, protocols, and standard reference materials in use. This paper addresses the comparability of inductively coupled plasma mass spectrometry, quantitative neutron capture radiography, and prompt gamma activation analysis for the determination of boron in biological samples. It was possible to demonstrate that three different methods relying on three different principles of sample preparation and boron detection can be validated against each other and yield consistent results for both blood and tissue samples. The samples were obtained during a clinical study for the application of BNCT for liver malignancies and therefore represent a realistic situation for boron analysis. PMID:22918535

  10. Intercomparison of inductively coupled plasma mass spectrometry, quantitative neutron capture radiography, and prompt gamma activation analysis for the determination of boron in biological samples

    Energy Technology Data Exchange (ETDEWEB)

    Schuetz, C.L. [University of Mainz, Institute for Nuclear Chemistry, Mainz (Germany); Johannes Gutenberg-University of Mainz, Institute for Nuclear Chemistry, Mainz (Germany); Brochhausen, C. [University of Mainz, Institute of Pathology, Mainz (Germany); Hampel, G.; Iffland, D.; Schmitz, T.; Stieghorst, C.; Kratz, J.V. [University of Mainz, Institute for Nuclear Chemistry, Mainz (Germany); Kuczewski, B. [Regional Council Darmstadt, Darmstadt (Germany); Otto, G. [University of Mainz, Department of Hepatobiliary, Pancreatic and Transplantation Surgery, Mainz (Germany)

    2012-10-15

    Boron determination in blood and tissue samples is a crucial task especially for treatment planning, preclinical research, and clinical application of boron neutron capture therapy (BNCT). Comparison of clinical findings remains difficult due to a variety of analytical methods, protocols, and standard reference materials in use. This paper addresses the comparability of inductively coupled plasma mass spectrometry, quantitative neutron capture radiography, and prompt gamma activation analysis for the determination of boron in biological samples. It was possible to demonstrate that three different methods relying on three different principles of sample preparation and boron detection can be validated against each other and yield consistent results for both blood and tissue samples. The samples were obtained during a clinical study for the application of BNCT for liver malignancies and therefore represent a realistic situation for boron analysis. (orig.)

  11. Spatial and temporal mapping of 10B distrubtion in vivo using nuclear reactor-based prompt gamma neutron activation analysis and image reconstruction techniques. Final Report

    International Nuclear Information System (INIS)

    This project involved the development of a method for in vivo prompt gamma neutron activation analysis for the investigation of Boron-10 distribution in a rabbit knee. The overall objective of this work was a robust approach for rapid screening of new 10B-labelled compounds to determine their suitability for use in the treatment of rheumatoid arthritis via Boron Neutron Capture Synovectomy (BNCS). For BNCS it is essential to obtain a compound showing high uptake levels in the synovium and long residence time in the joints. Previously the in vivo uptake behavior of potential compounds was evaluated in the arthritic knee joints of rabbits via extensive dissection studies. These studies are very labor-intensive and involve sacrificing large numbers of animals. An in vivo 10B screening approach was developed to provide initial evaluation of potential compounds. Only those compounds showing positive uptake and retention characteristics will be evaluated further via dissection studies. No further studies will be performed with compounds showing rapid clearance and/or low synovial uptake. Two approaches to in vivo screening were investigated using both simulation methods and experimentation. Both make use of neutron beams generated at the MIT Research Reactor. The first, Transmission Computed Tomography (TCT) was developed and tested but was eventually rejected due to very limited spatial resolution using existing reactor beams. The second, in vivo prompt gamma neutron activation analysis (IVPGNAA) was much more promising. IVPGNAA was developed using computer simulation and physical measurement coupled with image reconstruction techniques. The method was tested in arthritic New Zealand rabbits previously injected intra-articularly with three boron labeled compounds and shown to be effective in providing information regarding uptake level and residence time of 10B in the joint

  12. Detailed Study of the Angular Correlations in the Prompt Neutron Emission in Spontaneous Fission of 252Cf

    Science.gov (United States)

    Kopatch, Yu.; Chietera, A.; Stuttgé, L.; Gönnenwein, F.; Mutterer, M.; Gagarski, A.; Guseva, I.; Chernysheva, E.; Dorvaux, O.; Hambsch, F.-J.; Hanappe, F.; Mezentseva, Z.; Telezhnikov, S.

    An experiment has been performed at IPHC Strasbourg, aimed at the detailed investigation of angular correlations in the neutron emission from spontaneous fission of 252Cf. Fission fragments were measured by the angle-sensitive double ionization chamber CODIS while neutrons were detected by a set of 60 DEMON scintillator counters. The main aim of the experiment is the observation of the correlation between the fragment spins and neutron emission anisotropy. Preliminary results, based on the Monte-Carlo simulations, as well as the preliminary analysis of the experimental data are shown.

  13. Neutron capture on (94)Zr: Resonance parameters and Maxwellian-averaged cross sections

    CERN Document Server

    Tagliente, G; Fujii, K; Abbondanno, U; Aerts, G; Alvarez, H; Alvarez-Velarde, F; Andriamonje, S; Andrzejewski, J; Audouin, L; Badurek, G; Baumann, P; Becvar, F; Belloni, F; Berthoumieux, E; Bisterzo, S; Calvino, F; Calviani, M; Cano-Ott, D; Capote, R; Carrapico, C; Cennini, P; Chepel, V; Chiaveri, E; Colonna, N; Cortes, G; Couture, A; Cox, J; Dahlfors, M; David, S; Dillmann, I; Domingo-Pardo, C; Dridi, W; Duran, I; Eleftheriadis, C; Embid-Segura, M; Ferrari, A; Ferreira-Marques, R; Furman, W; Gallino, R; Goncalves, I; Gonzalez-Romero, E; Gramegna, F; Guerrero, C; Gunsing, F; Haas, B; Haight, R; Heil, M; Herrera-Martinez, A; Jericha, E; Kappeler, F; Kadi, Y; Karadimos, D; Karamanis, D; Kerveno, M; Kossionides, E; Krticka, M; Lamboudis, C; Leeb, H; Lindote, A; Lopes, I; Lozano, M; Lukic, S; Marganiec, J; Marrone, S; Martinez, T; Massimi, C; Mastinu, P; Mengoni, A; Moreau, C; Mosconi, M; Neves, F; Oberhummer, H; O'Brien, S; Pancin, J; Papachristodoulou, C; Papadopoulos, C; Paradela, C; Patronis, N; Pavlik, A; Pavlopoulos, P; Perrot, L; Pigni, M.T; Plag, R; Plompen, A; Plukis, A; Poch, A; Praena, J; Pretel, C; Quesada, J; Rauscher, T; Reifarth, R; Rosetti, M; Rubbia, C; Rudolf, G; Rullhusen, P; Salgado, J; Santos, C; Sarchiapone, L; Savvidis, I; Stephan, C; Tain, J.L; Tassan-Got, L; Tavora, L; Terlizzi, R; Vannini, G; Vaz, P; Ventura, A; Villamarin, D; Vincente, M.C; Vlachoudis, V; Vlastou, R; Voss, F; Walter, S; Wiescher, M; Wisshak, K

    2011-01-01

    The neutron capture cross sections of the Zr isotopes play an important role in nucleosynthesis studies. The s-process reaction flow between the Fe seed and the heavier isotopes passes through the neutron magic nucleus (90)Zr and through (91,92,93,94)Zr, but only part of the flow extends to (96)Zr because of the branching point at (95)Zr. Apart from their effect on the s-process flow, the comparably small isotopic (n, gamma) cross sections make Zr also an interesting structural material for nuclear reactors. The (94)Zr (n, gamma) cross section has been measured with high resolution at the spallation neutron source n_TOF at CERN and resonance parameters are reported up to 60 keV neutron energy.

  14. In vivo prompt gamma neutron activation analysis for the screening of boron-10 distribution in a rabbit knee: a simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, X; Yanch, J [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States); Clackdoyle, R [Laboratoire Hubert Curien, Mixed Research Unit (UMR) 5516, CNRS and Universite Jean Monnet, Saint Etienne (France); Shortkroff, S [Department of Orthopedic Surgery, Brigham and Women' s Hospital, Harvard Medical School, Boston, MA (United States)

    2008-05-21

    Boron neutron capture synovectomy (BNCS) is under development as a potential treatment modality for rheumatoid arthritis (RA). RA is characterized by the inflammation of the synovium (the membrane lining articular joints), which leads to pain and a restricted range of motion. BNCS is a two-part procedure involving the injection of a boronated compound directly into the diseased joint followed by irradiation with a low-energy neutron beam. The neutron capture reactions taking place in the synovium deliver a local, high-linear energy transfer (LET) dose aimed at destroying the inflamed synovial membrane. For successful treatment via BNCS, a boron-labeled compound exhibiting both high synovial uptake and long retention time is necessary. Currently, the in vivo uptake behavior of potentially useful boronated compounds is evaluated in the knee joints of rabbits in which arthritis has been induced. This strategy involves the sacrifice and dissection of a large number of animals. An in vivo {sup 10}B screening approach is therefore under investigation with the goal of significantly reducing the number of animals needed for compound evaluation via dissection studies. The 'in vivo prompt gamma neutron activation analysis' (IVPGNAA) approach uses a narrow neutron beam to irradiate the knee from several angular positions following the intra-articular injection of a boronated compound whose uptake characteristics are unknown. A high-purity germanium detector collects the 478 keV gamma photons produced by the {sup 10}B capture reactions. The {sup 10}B distribution in the knee is then reconstructed by solving a system of simultaneous equations using a weighted least squares algorithm. To study the practical feasibility of IVPGNAA, simulation data were generated with the Monte Carlo N-particle transport code. The boron-containing region of a rabbit knee was partitioned into 8 compartments, and the {sup 10}B prompt gamma signals were tallied from 16 angular positions

  15. In vivo prompt gamma neutron activation analysis for the screening of boron-10 distribution in a rabbit knee: a simulation study

    Science.gov (United States)

    Zhu, X.; Clackdoyle, R.; Shortkroff, S.; Yanch, J.

    2008-05-01

    Boron neutron capture synovectomy (BNCS) is under development as a potential treatment modality for rheumatoid arthritis (RA). RA is characterized by the inflammation of the synovium (the membrane lining articular joints), which leads to pain and a restricted range of motion. BNCS is a two-part procedure involving the injection of a boronated compound directly into the diseased joint followed by irradiation with a low-energy neutron beam. The neutron capture reactions taking place in the synovium deliver a local, high-linear energy transfer (LET) dose aimed at destroying the inflamed synovial membrane. For successful treatment via BNCS, a boron-labeled compound exhibiting both high synovial uptake and long retention time is necessary. Currently, the in vivo uptake behavior of potentially useful boronated compounds is evaluated in the knee joints of rabbits in which arthritis has been induced. This strategy involves the sacrifice and dissection of a large number of animals. An in vivo 10B screening approach is therefore under investigation with the goal of significantly reducing the number of animals needed for compound evaluation via dissection studies. The 'in vivo prompt gamma neutron activation analysis' (IVPGNAA) approach uses a narrow neutron beam to irradiate the knee from several angular positions following the intra-articular injection of a boronated compound whose uptake characteristics are unknown. A high-purity germanium detector collects the 478 keV gamma photons produced by the 10B capture reactions. The 10B distribution in the knee is then reconstructed by solving a system of simultaneous equations using a weighted least squares algorithm. To study the practical feasibility of IVPGNAA, simulation data were generated with the Monte Carlo N-particle transport code. The boron-containing region of a rabbit knee was partitioned into 8 compartments, and the 10B prompt gamma signals were tallied from 16 angular positions. Results demonstrate that for this

  16. Neutron Thermal Cross Sections, Westcott Factors, Resonance Integrals, Maxwellian Averaged Cross Sections and Astrophysical Reaction Rates Calculated from Major Evaluated Data Libraries

    OpenAIRE

    Pritychenko, B.; Mughabghab, S.F.

    2012-01-01

    We present calculations of neutron thermal cross sections, Westcott factors, resonance integrals, Maxwellian-averaged cross sections and astrophysical reaction rates for 843 ENDF materials using data from the major evaluated nuclear libraries and European activation file. Extensive analysis of newly-evaluated neutron reaction cross sections, neutron covariances, and improvements in data processing techniques motivated us to calculate nuclear industry and neutron physics quantities, produce s-...

  17. Prompt nuclear analysis bibliography 1976

    International Nuclear Information System (INIS)

    A prompt nuclear analysis bibliography published in 1974 has been updated to include literature up to the end of 1976. The number of publications has more than doubled since mid-1973. The bibliography is now operated as a computer file and searches can be made on key words and parameters. Tables of references are given for each of the categories: backscattering, ion-ion, ion-gamma, ion-neutron, neutron-gamma, neutron-neutron and gamma-ray-induced reactions

  18. Study on radioactivation analysis of silicate in marine samples by prompt gamma-ray analysis with cold neutron

    Energy Technology Data Exchange (ETDEWEB)

    Shiomoto, Akihiro [National Research Institute of Far Seas Fisheries, Shimizu, Shizuoka (Japan)

    1999-02-01

    To observe the silicate behavior in marine samples, Skeletonema costatum was incubated for 11 days at 18degC. 5 ml culture medium was filtered and measured by prompt gamma-ray analysis in every day. We could not observe silicate, but boron by the method, the same as Phaeodactylum triconum. The boron content increased with increasing the number of cell. Accordingly, increase of Skeletonema costatum could be traced by boron. If ratio of content of two elements was determined, the incorporate velocity of silicate into Skeletonema costatum was able to be observed. (S.Y.)

  19. Gadolinium detection via in vivo prompt gamma neutron activation analysis following gadolinium-based contrast agent injection: a pilot study in 10 human participants

    International Nuclear Information System (INIS)

    Gadolinium (Gd) based contrast agents are routinely used as part of many magnetic resonance imaging (MRI) procedures. The widespread use of these agents and concerns about Gd toxicity, motivated us to develop a monitoring procedure that could non-invasively measure quantitatively potential retention of toxic free Gd in tissues after use of the agent. We have been developing a method to measure Gd painlessly and non-invasively by prompt gamma neutron activation analysis. In this paper we present the results of a pilot study where we show that we can measure Gd, quantitatively in vivo, in the lower leg muscle of 10 participants. A series of three neutron leg scans were performed. The effective radiation dose for a single neutron leg scan was very low, 0.6 µSv, so multiple scans were possible. Calibration phantom and in vivo detection limits were determined to be identical: 0.58 ppm. Gd was not detectable in muscle prior to exposure to the contrast agent Gadovist®. Gd was detected, at greater than 99% confidence, in 9 participants within 1 h of contrast administration and in 1 participant approximately 3.3 h post-contrast administration. The measured concentrations of Gd ranged from 2.0 to 17.3 ppm (6.9 to 56 uncertainties different from zero). No detectable Gd was measured in any participant in the third neutron scan (conducted 0.7 to 5.9 d post-contrast). The results of this study validate our new measurement technology. This technique could be used as a non-invasive monitoring procedure for exposure and retention of Gd from Gd-based chelates used in MRI. (paper)

  20. Monte Carlo simulation of prompt γ-ray spectra from depleted uranium under D-T neutron irradiation and electron recoil spectra in a liquid scintillator detector

    Science.gov (United States)

    Jian-Guo, Qin; Cai-Feng, Lai; Rong, Liu; Tong-Hua, Zhu; Xin-Wei, Zhang; Bang-Jiao, Ye

    2016-03-01

    To overcome the problem of inefficient computing time and unreliable results in MCNP5 calculation, a two-step method is adopted to calculate the energy deposition of prompt γ-rays in detectors for depleted uranium spherical shells under D-T neutron irradiation. In the first step, the γ-ray spectrum for energy below 7 MeV is calculated by MCNP5 code; secondly, the electron recoil spectrum in a BC501A liquid scintillator detector is simulated based on EGSnrc Monte Carlo Code with the γ-ray spectrum from the first step as input. The comparison of calculated results with experimental ones shows that the simulations agree well with experiment in the energy region 0.4-3 MeV for the prompt γ-ray spectrum and below 4 MeVee for the electron recoil spectrum. The reliability of the two-step method in this work is validated. Supported by the National Natural Science Foundation of China (91226104) and National Special Magnetic Confinement Fusion Energy Research, China (2015GB108001)

  1. Californium interrogation prompt neutron (CIPN) instrument for non-destructive assay of spent nuclear fuel-Design concept and experimental demonstration

    Science.gov (United States)

    Henzlova, D.; Menlove, H. O.; Rael, C. D.; Trellue, H. R.; Tobin, S. J.; Park, Se-Hwan; Oh, Jong-Myeong; Lee, Seung-Kyu; Ahn, Seong-Kyu; Kwon, In-Chan; Kim, Ho-Dong

    2016-01-01

    This paper presents results of the first experimental demonstration of the Californium Interrogation Prompt Neutron (CIPN) instrument developed within a multi-year effort launched by the Next Generation Safeguards Initiative Spent Fuel Project of the United States Department of Energy. The goals of this project focused on developing viable non-destructive assay techniques with capabilities to improve an independent verification of spent fuel assembly characteristics. For this purpose, the CIPN instrument combines active and passive neutron interrogation, along with passive gamma-ray measurements, to provide three independent observables. This paper describes the initial feasibility demonstration of the CIPN instrument, which involved measurements of four pressurized-water-reactor spent fuel assemblies with different levels of burnup and two initial enrichments. The measurements were performed at the Post-Irradiation Examination Facility at the Korea Atomic Energy Institute in the Republic of Korea. The key aim of the demonstration was to evaluate CIPN instrument performance under realistic deployment conditions, with the focus on a detailed assessment of systematic uncertainties that are best evaluated experimentally. The measurements revealed good positioning reproducibility, as well as a high degree of insensitivity of the CIPN instrument's response to irregularities in a radial burnup profile. Systematic uncertainty of individual CIPN instrument signals due to assembly rotation was found to be orientation in the instrument.

  2. Approximate Solution of the Point Reactor Kinetic Equations of Average One-Group of Delayed Neutrons for Step Reactivity Insertion

    Directory of Open Access Journals (Sweden)

    S. Yamoah

    2012-04-01

    Full Text Available The understanding of the time-dependent behaviour of the neutron population in a nuclear reactor in response to either a planned or unplanned change in the reactor conditions is of great importance to the safe and reliable operation of the reactor. In this study two analytical methods have been presented to solve the point kinetic equations of average one-group of delayed neutrons. These methods which are both approximate solution of the point reactor kinetic equations are compared with a numerical solution using the Euler’s first order method. To obtain accurate solution for the Euler method, a relatively small time step was chosen for the numerical solution. These methods are applied to different types of reactivity to check the validity of the analytical method by comparing the analytical results with the numerical results. From the results, it is observed that the analytical solution agrees well with the numerical solution.

  3. Fast neutron spectrum unfolding of a TRIGA Mark II reactor and measurement of spectrum-averaged cross sections. Integral tests of differential cross sections of neutron threshold reactions

    Energy Technology Data Exchange (ETDEWEB)

    Uddin, M.S.; Hossain, S.M.; Khan, R. [Atomic Energy Research Establishment, Dhaka (Bangladesh). Inst. of Nuclear Science and Technology (INST); Sudar, S. [Debrecen Univ. (Hungary). Inst. of Experimental Physics; Zulquarnain, M.A. [Bangladesh Atomic Energy Commission, Dhaka (Bangladesh); Qaim, S.M. [Forschungszentrum Juelich (Germany). Inst. fuer Neurowissenschaften und Medizin (INM-5)

    2013-07-01

    The spectrum of fast neutrons having energies from 0.5 to 20 MeV in the core of the 3MW TRIGA Mark II reactor at Savar, Dhaka, Bangladesh, was unfolded by activating several metal foils to induce threshold nuclear reactions covering the whole spectrum, and then doing necessary iterative calculations utilizing the activation results and the code SULSA. The analysed shape of the spectrum in the TRIGA core was found to be similar to that of the pure {sup 235}U-fission spectrum, except for the energies between 0.5 and 1.5 MeV, where it was slightly higher than the fission spectrum. Spectrum-averaged cross sections were determined by integral measurements. The integral values measured in this work were compared with the recommended values for a pure fission spectrum as well as with the integrated data deduced from measured and evaluated excitation functions of a few reactions given in some data files. The good agreement between integral measurements and integrated data in case of well-investigated reactions shows that the fast neutron field at the TRIGA Mark II reactor can be used for validation of evaluated data of neutron threshold reactions. (orig.)

  4. Fast neutron spectrum unfolding of a TRIGA Mark II reactor and measurement of spectrum-averaged cross sections. Integral tests of differential cross sections of neutron threshold reactions

    International Nuclear Information System (INIS)

    The spectrum of fast neutrons having energies from 0.5 to 20 MeV in the core of the 3MW TRIGA Mark II reactor at Savar, Dhaka, Bangladesh, was unfolded by activating several metal foils to induce threshold nuclear reactions covering the whole spectrum, and then doing necessary iterative calculations utilizing the activation results and the code SULSA. The analysed shape of the spectrum in the TRIGA core was found to be similar to that of the pure 235U-fission spectrum, except for the energies between 0.5 and 1.5 MeV, where it was slightly higher than the fission spectrum. Spectrum-averaged cross sections were determined by integral measurements. The integral values measured in this work were compared with the recommended values for a pure fission spectrum as well as with the integrated data deduced from measured and evaluated excitation functions of a few reactions given in some data files. The good agreement between integral measurements and integrated data in case of well-investigated reactions shows that the fast neutron field at the TRIGA Mark II reactor can be used for validation of evaluated data of neutron threshold reactions. (orig.)

  5. Experimental determination of prompt neutron decay constant of IPEN/MB-01 reactor by Rossi-{alpha} method; Determinacao experimental da constante de decaimento de neutrons prontos do reator IPEN/MB-01 via o metodo Rossi-{alpha}

    Energy Technology Data Exchange (ETDEWEB)

    Kuramoto, Renato; Santos, Adimir dos; Jerez, Rogerio; Bitelli, Ulysses D' Utra; Diniz, Ricardo; Madi, Tufic [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: ryrkuram@ipen.br

    2005-07-01

    One major objective of this work is to experimentally estimate the prompt neutron decay constant, {alpha}, on the IPEN/MB-01 research reactor at Sao Paulo. In order to achieve our goal, we will use a microscopic noise technique called Rossi-{alpha} method. This method is based on the statistical nature of the fission-chain process. Using a coincidence acquisition system, the rationale is to experimentally determine the probability distribution of detecting neutrons from the same chain. Through a leastsquares fit of this distribution we estimate {alpha}=({beta}{sub eff}-{rho})/{lambda}. The {alpha} parameter will be measured for different sub-critical levels, and the ratio {beta}{sub eff}/{lambda} is obtained via extrapolation to {rho}=0. A specific acquisition system for Rossi-{alpha} measurements has been developed in order to achieve our objective. This system is based on a multichannel scaler controlled by virtual instruments that records the timing of all neutron events, allowing data analysis during the acquisition. The first measurements were performed using one BF{sub 3} detectors positioned at the center of the core of IPEN/MB-01 research reactor. In this work we will present a preliminary set of Rossi-{alpha} measurements performed on the IPEN/MB-01 research reactor at Sao Paulo. (author)

  6. Evaluation of an in vivo prompt gamma neutron activation facility for body composition studies in critically ill intensive care patients: results on 41 normals

    International Nuclear Information System (INIS)

    A programme of metabolic and nutritional research is being undertaken in critically ill patients requiring intensive care. Central to this research is the measurement of the three nutritionally important compartments of body composition, protein, fat, and water by a combination of tritium dilution and prompt gamma in vivo neutron activation analysis (IVNAA). In this paper a calibration technique is presented that enables absolute estimates of total body nitrogen (TBN) to be made using prompt gamma IVNAA in critically ill patients with gross abnormalities in body composition, especially in their state of hydration. This technique, which is independent of skinfold anthropometry and does not make a priori assumptions about the ratios of major body compartments, has been applied to 41 normal volunteers and the derived values for nitrogen compared with values obtained by applying three currently used calibration methods to the same experimental data. The empirical equations relate TBN in normal people to age, height, weight and sex. The mean ratios of experimental to predicted TBN (with SEMs) are 1.013 +/- 0.017 and 1.002 +/- 0.014, respectively. Mean values of the ratio of TBN to fat-free mass (0.0340 +/- 0.0004) and of total body water to fat-free mass (0.716 +/- 0.002) agree closely with values reported elsewhere for normals by a variety of techniques including chemical analysis. Finally, TBN results based on the four different calibration methods are presented for five surgical patients, demonstrating the importance of the calibration method on estimates of TBN in patients with abnormal body composition. It is concluded that this technique will provide accurate estimates of the total body content of protein, water, and fat in intensive care patients

  7. PGNAA 方法学的发展与现状%Development and Status of Prompt Gamma Neutron Activation Analysis Technique Methodology

    Institute of Scientific and Technical Information of China (English)

    王兴华; 孙洪超; 姚永刚; 肖才锦; 张贵英; 金象春; 华龙; 周四春

    2014-01-01

    Prompt Gamma Neutron Activation Analysis (PGNAA) is one of the nonde‐structive and On‐line measurement of nuclear analytical methods ,There are more than 30 PGNAA laboratories which are established based on the research reactor currently . The basic principle and the application field of three kinds of analytical method of PGNAA were introduced ,such as the relative comparison method、calibration method、k0‐factor method .T he short life nuclides is proposed using the beam chopper technique in order to improve the measurement accuracy . T he internal standard method w as proposed for that large sample neutron measurement that brings self absorption and gamma‐ray self shielding effect .The PGNAA system was introduced at CARR .It pro‐vides methodology reference to establish the prompt gamma activation analysis on the base of CARR for our country .%瞬发伽马中子活化分析(PGNAA)为非破坏性、在线测量的核分析方法。目前国际上有30多座研究堆建立了PGNAA实验室。本文介绍了三种定量瞬发伽马活化分析方法:相对法、校准曲线法、k0因子法,阐述了基本原理及其应用领域,以及针对短寿命核素高精度测量的束流斩波器技术,针对大样品测量带来的中子自吸收和伽马自屏蔽效应的内标法。此外还简介了基于CARR堆的热中子瞬发伽马活化分析装置进展情况,对国内的PGNAA问题进行了探讨。

  8. Radiological Safety Aspects of the new Deuterium-Deuterium (D-D) neutron generator for prompt gamma-ray neutron activation analysis

    International Nuclear Information System (INIS)

    This document is a safety and a security report for the new neutron generator the High Intensity Mutli-Purpose DD-110 of the National Center for Nuclear Sciences and Technologies of Tunis (CNSTN). It aims to introduce the standards of the International Atomic Energy Agency (IAEA) to the facility in question. Overall, this report draws its profit from the official safety reports of the IAEA. First, we study the anatomy of the accelerator by breaking it down into various compartments and examining the case of leaks that may arise. Thanks to this part, the reader gets used to the peculiarity of the system, and we can meet and provide procedures for some typical scenarios of mechanical malfunction. Second, we adapt some theoretical concepts related to the quantification of the radioactivity, the thickness of the armoring, the utilization factor, and the quality factor. Thus, we become able to list of types of these radiations, dangers, risks and their sources. We treat the production, the cross section, the interaction with the environment and the separated removal of neutrons, gamma, X-photons, beta particles, and electrons. In addition, we examine the phenomenon of activation of the compartments, the danger samples of activation, the danger associated with the modulation of the pressure and the danger of explosion. In light of this study, we handle mathematically the question of the armoring and the concept of radiation protection. Therefore, we present a practical methodology to implement a monitoring system and a technicality in the interpretation of the measurements. Finally, we discuss the practical aspect by introducing security governance to CNSTN, and establishing a program of general, radiological and specific security.

  9. In vivo measurement of total body chlorine using the 8. 57 MeV prompt de-excitation following thermal neutron capture

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, S.; Plank, L.D.; Knight, G.S.; Hill, G.L. (Auckland Hospital (New Zealand). University Dept. of Surgery)

    1993-01-01

    Prompt gamma neutron activation analysis with [sup 238]Pu/Be sources is used to measure total body chlorine (TBC1) in vivo following the reaction [sup 35]Cl(n,[gamma])[sup 36]Cl. The precision of the method is 4.9% (CV). To assess accuracy an anthropomorphic phantom of minced meat was constructed. Replicate scans of this phantom yielded a mean total chlorine not significantly different from the chemical analysis value. The subject dose equivalent for the activation measurement is less than 0.3 mSv. Mean TBC1 values for 63 male and 107 female healthy volunteers were in broad agreement with predicted amounts based on multiple regression equations developed at other centres from measurements using the delayed gamma approach. Good agreement was observed in 76 volunteers between total body water (TBW) measured by tritium dilution, after correction for non-aqueous hydrogen exchange, and TBW derived from the sum of extracellular water and intracellular water as measured by TBCl and total body potassium (TBK). (Author).

  10. Studies on fission with ALADIN. Precise and simultaneous measurement of fission yields, total kinetic energy and total prompt neutron multiplicity at GSI

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Julie-Fiona; Taieb, Julien; Chatillon, Audrey; Belier, Gilbert; Boutoux, Guillaume; Ebran, Adeline; Gorbinet, Thomas; Grente, Lucie; Laurent, Benoit; Pellereau, Eric [CEA DAM Bruyeres-le-Chatel, Arpajon (France); Alvarez-Pol, Hector; Ayyad, Yassid; Benlliure, Jose; Cortina Gil, Dolores; Caamano, Manuel; Fernandez Dominguez, Beatriz; Paradela, Carlos; Ramos, Diego; Rodriguez-Sanchez, Jose-Luis; Vargas, Jossitt [Universidad de Santiago de Compostela, Santiago de Compostela (Spain); Audouin, Laurent; Tassan-Got, Laurent [CNRS/IN2P3, IPNO, Orsay (France); Aumann, Thomas [Technische Universitaet Darmstadt, Darmstadt (Germany); Casarejos, Enrique [Universidad de Vigo, Vigo (Spain); Farget, Fanny; Rodriguez-Tajes, Carme [CNRS/IN2P3, GANIL, Caen (France); Heinz, Andreas [Chalmers University of Technology, Gothenburg (Sweden); Jurado, Beatriz [CNRS/IN2P3, CENBG, Gradignan (France); Kelic-Heil, Aleksandra; Kurz, Nikolaus; Nociforo, Chiara; Pietri, Stephane; Rossi, Dominic; Schmidt, Karl-Heinz; Simon, Haik; Voss, Bernd; Weick, Helmut [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany)

    2015-12-15

    A novel technique for fission studies, based on the inverse kinematics approach, is presented. Following pioneering work in the nineties, the SOFIA Collaboration has designed and built an experimental set-up dedicated to the simultaneous measurement of isotopic yields, total kinetic energies and total prompt neutron multiplicities, by fully identifying both fission fragments in coincidence, for the very first time. This experiment, performed at GSI, permits to study the fission of a wide variety of fissioning systems, ranging from mercury to neptunium, possibly far from the valley of stability. A first experiment, performed in 2012, has provided a large array of unprecedented data regarding the nuclear fission process. An excerpt of the results is presented. With this solid starter, further improvements of the experimental set-up are considered, which are consistent with the expected developments at the GSI facility, in order to measure more fission observables in coincidence. The completeness reached in the SOFIA data, permits to scrutinize the correlations between the interesting features of fission, offering a very detailed insight in this still unraveled mechanism. (orig.)

  11. Elemental activation analysis with decay and prompt gamma ray techniques, using isotopic neutron sources and a nuclear research reactor. Part of a coordinated programme on nuclear-based techniques in geology and mineral prospecting

    International Nuclear Information System (INIS)

    This is to review the research activities carried out through the IAEA research Project 1697/RB ''Elemental activation analysis with decay and prompt gamma ray techniques, using isotopic neutron sources and the nuclear research reactor. The programme of work includes: a) Development of decay and prompt gamma ray activation techniques for mineral exploration. b) Development of epithermal NAA in addition to thermal NAA especially for gold ore. c) Development of non-destructive insitu elemental analysis with decay and prompt gamma ray techniques using isotopic neutron sources. A joint programme has been established with the Egyptian Geological Surrey and Mining Authority for using nuclear techniques in evaluating gold prospects of several ancient gold mines and investigating several tin-tantalum deposits, which were discovered over the last few years. Two sources of neutrons were used for irradiation, one of the dry channels of the two megawatts research reactor, ET-RR-1 for laboratory studies, and a Pu-Be neutron source in paraffin assembly for possible insitu work

  12. Evaluation of average neutron resonance parameters of actinides with the account of experimental resolution and discrimination threshold. Final report for the period 15 December 1996 - 14 December 1997

    International Nuclear Information System (INIS)

    New evaluation of average resonance parameters for 32 isotopes of the actinide region (229Th-252Cf) was completed. Obtained values of average level spacings produce a smooth systematics of the main level density parameter. The results were included into the Starter File of the Reference Input Parameter Library (segment Average Neutron Resonances) and officially released on 15 May 1998. The numerical results are available from the Internet (http://iaeand.iaea.or.at/ripl) and on CD-ROM. (author)

  13. Determination of the fission-neutron averaged cross sections of some high-energy threshold reactions of interest for reactor dosimetry

    CERN Document Server

    Arribere, M A; Ribeiro-Guevara, S; Korochinsky, S; Blostein, J J

    2003-01-01

    For three high threshold reactions, we have measured the cross sections averaged over a sup 2 sup 3 sup 5 U fission neutron spectrum. The measured reactions, and corresponding averaged cross sections found, are: sup 1 sup 2 sup 7 I(n,2n) sup 1 sup 2 sup 6 I, (1.36+-0.12) mb; sup 9 sup 0 Zr(n,2n) sup 8 sup 9 sup m Zr, (13.86+-0.83) mu b; and sup 5 sup 8 Ni(n,d+np+pn) sup 5 sup 7 Co, (274+-15) mu b; all referred to the well known standard of (111+-3) mb for the sup 5 sup 8 Ni(n,p) sup 5 sup 8 sup m sup + sup g Co averaged cross section. The measured cross sections are of interest in nuclear engineering for the characterization of the fast neutron component in the energy distribution of reactor neutrons. (author)

  14. The final power calibration of the IPEN/MB-01 nuclear reactor for various configurations obtained from the measurements of the absolute average neutron flux

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Alexandre Fonseca Povoa da, E-mail: alexandre.povoa@mar.mil.br [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), Sao Paulo, SP (Brazil); Bitelli, Ulysses d' Utra; Mura, Luiz Ernesto Credidio; Lima, Ana Cecilia de Souza; Betti, Flavio; Santos, Diogo Feliciano dos, E-mail: ubitelli@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    The use of neutron activation foils is a widely spread technique applied to obtain nuclear parameters then comparing the results with those calculated using specific methodologies and available nuclear data. By irradiation of activation foils and subsequent measurement of its induced activity, it is possible to determine the neutron flux at the position of irradiation. The power level during operation of the reactor is a parameter which is directly proportional to the average neutron flux throughout the core. The objective of this work is to gather data from irradiation of gold foils symmetrically placed along a cylindrically configured core which presents only a small excess reactivity in order to derive the power generated throughout the spatial thermal and epithermal neutron flux distribution over the core of the IPEN/MB-01 Nuclear Reactor, eventually lending to a proper calibration of its nuclear channels. The foils are fixed in a Lucite plate then irradiated with and without cadmium sheaths so as to obtain the absolute thermal and epithermal neutron flux. The correlation between the average power neutron flux resulting from the gold foils irradiation, and the average power digitally indicated by the nuclear channel number 6, allows for the calibration of the nuclear channels of the reactor. The reactor power level obtained by thermal neutron flux mapping was (74.65 ± 2.45) watts to a mean counting per seconds of 37881 cps to nuclear channel number 10 a pulse detector, and 0.719.10{sup -5} ampere to nuclear linear channel number 6 (a non-compensated ionization chamber). (author)

  15. Analysis of neutron flux distribution using the Monte Carlo method for the feasibility study of the Prompt Gamma Activation Analysis technique at the IPR-R1 TRIGA reactor

    Energy Technology Data Exchange (ETDEWEB)

    Guerra, Bruno T.; Pereira, Claubia, E-mail: brunoteixeiraguerra@yahoo.com.br, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (DEN/UFMG), Belo Horizonte, MG (Brazil). Departmento de Energia Nuclear; Soares, Alexandre L.; Menezes, Maria Angela B.C., E-mail: menezes@cdtn.br, E-mail: asleal@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    The IPR-R1 is a reactor type TRIGA, Mark-I model, manufactured by the General Atomic Company and installed at Nuclear Technology Development Centre (CDTN), Brazilian Commission for Nuclear Energy (CNEN), in Belo Horizonte, Brazil. It is a light water moderated and cooled, graphite-reflected, open-pool type research reactor and operates at 100 kW. It presents low power, low pressure, for application in research, training and radioisotopes production. The fuel is an alloy of zirconium hydride and uranium enriched at 20% in {sup 235}U. The implementation of the PGNAA (Prompt Gamma Neutron Activation Analysis) using this research reactor will significantly increase in number of chemical elements analysed and the kind of matrices. A project is underway in order to implement this technique at CDTN. The objective of this study was to contribute in feasibility analysis of implementing this technique. For this purpose, MCNP is being used. Some variance reduction tools in the methodology, that has been already developed, was introduced for calculating of the neutron flux in the neutron extractor inclined. The objective was to reduce the code error and thereby increasing the reliability of the results. With the implementation of the variance reduction tools, the results of the thermal and epithermal neutron fluxes presented a significant improvement in both calculations. (author)

  16. Onset of collectivity in neutron-rich Sr and Kr isotopes: Prompt spectroscopy after Coulomb excitation at REX-ISOLDE, CERN

    Directory of Open Access Journals (Sweden)

    Clément E.

    2013-12-01

    Full Text Available A rapid onset of quadrupole deformation is known to occur around the neutron number 60 in the neutron-rich Zr and Sr isotopes. This shape change has made the neutron-rich A = 100 region an active area of experimental and theoretical studies for many decades now. We report in this contribution new experimental results in the neutron rich 96,98Sr investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross section supporting the scenario of shape coexistence/change at N = 60. Future perspectives are presented including the recent experimental campaign performed at ILL-Grenoble.

  17. Measurement of the generation ratio of 233U and the average radiation capture cross section of 232Th with 232ThO2 irradiated by fast neutrons

    International Nuclear Information System (INIS)

    Background: Thorium-Uranium cycle plays an important role in the future's power production technology. Nuclear data involved are urgently needed for engineering design and other purposes since there are obvious differences between the existing evaluated data. Macroscopic neutron integral experiment can be used as a good tool to survey the confusion. Purpose: Macroscopic neutron integral experiment based on radioactive method was carried out to measure the generation ratio of 233U nuclide and the average radiation capture cross section of 232Th while a ThO2 sample was irradiated by fast neutrons leakage from a fast critical facility. We expect that these data can be used as a reference for the research of Th-U cycle. Methods: Radiation capture reactions of 232Th nuclides occur when the nuclides are irradiated by neutrons. 233U nuclides will be generated after two cascade decays by emitting beta rays from the activation products, which are 233Th nuclides. The ThO2 sample was prepared as a slice of 20 mm×10 mm from 0.743 36-g ThO2 powders of 99.9% enriched. The neutron flux was measured by activation method which was 4.07x109 cm-2·s-1 at the sample's irradiation position while the facility worked at the power level of 180 watts. The leakage neutrons' energy distribution was calculated by MC method and it is very close to the fission spectrum with the averaged energy of 1.42 MeV. After irradiation and then a period of cooling time the gamma rays emitted from the sample were measured by an HPGe spectrometer which had been pre-calibrated. From these data the activity of 233Pa was calculated and then the generation ratio of 233U and the average radiation capture cross section of 232Th were calculated. The measured average radiation capture cross section was compared with the cross sections calculated based on the ENDFB-VH.1, CENDL-3.1, JENDL-4.0, BROND2.2 databases. Results: The measured generation ratio of 233U was 4.01×10-12 with an uncertainty of 6

  18. Average Number and Energy of Gamma-Rays Emitted as a Function of Fragment Mass in U235 Thermal-Neutron-Induced Fission

    International Nuclear Information System (INIS)

    The average number and energy of gamma-rays emitted as a function of fragment mass in U235 thermal-neutron-induced fission have been measured. A three-parameter correlation experimeni was performed in which two silicon suríace barrier detectors were used to measure the fission product energies, and a 5-in-diam., 4-in-thick Nal(Tl) scintillation crystal was used to measure the gamma-ray energies. Extreme care was taken in the experimental arrangement to avoid counting direct fission neutrons, scattered gamma-rays and neutrons, and other false events. Data were recorded event-by-event in a system similar to that used in previous energy correlation experiments at Oak Ridge, and were analysed according to a ''weighting method'' proposed by Maier-Leibnitz. The total number and energy of the gamma- rays for both fragments as a function of mass ratio were obtained directly. The number and energy of gamma- rays for individual fragment masses were determined by making use of the variation in laboratory angular distribution and energy of the gamma-rays emitted from moving fragments. In particular, the 0° to 180° ratio of the number of gamma-rays from a moving source emitting isotropically in its centre-of-mass system is proportional to 1 + 2 x 2v/c; similarly the 0° to 180° ratio in total gamma energy is proportional to 1 + 2 x3v/c. Thus by comparing appropriate ratios in the analysis for light and heavy fragments moving towards or away from the gamma-ray derector, one obtains these quantities as a function of individual fragment mass. Results of preliminary analyses show interesting similarities in behaviour to those for neutrons. Both the total energy and average quantum energy of gamma-rays are essentially constant over most of the range of mass ratios; however a broad minimum is observed for the total energy in the region where Mh ∼ 130, i. e. where ZH ∼ 50 or NH ∼ 82. An increase is observed in the total energy as the mass ratio approaches unity. The number

  19. On collapsing the Pu94242 average number of neutrons released per fission from the IAEA.LIB library with the WIMSD-5b code

    Energy Technology Data Exchange (ETDEWEB)

    Caldeira, Alexandre D. [Centro Tecnico Aeroespacial (CTA), Instituto de Estudos Avancados (IEAv), 12231-970 Sao Jose dos Campos, SP (Brazil)]. E-mail: alexdc@ieav.cta.br; Claro, Luiz H. [Centro Tecnico Aeroespacial (CTA), Instituto de Estudos Avancados (IEAv), 12231-970 Sao Jose dos Campos, SP (Brazil)

    2007-01-15

    It was verified after a fuel burnup calculation with the WIMSD-5b code using the IAEA.LIB library that the computed average number of neutrons released per fission of Pu94242 shows up as a Not-a-Number (NaN) for some energy groups. As this problem does not permit the use of the generated multigroup microscopic cross sections by a reactor calculation code, the value of 1.0E-38 barns was attributed to all energy groups of the IAEA.LIB library that have null values of multigroup microscopic fission cross sections for this material.

  20. Nuclear data for neutron emission in the fission process

    International Nuclear Information System (INIS)

    This document contains the proceedings of the IAEA Consultants' Meeting on Nuclear Data for Neutron Emission in the Fission Process, Vienna, 22 - 24 October 1990. Included are the conclusions and recommendations reached at the meeting and the papers presented by the meeting participants. These papers provide a review of the status of experimental and theoretical data on neutron emission in spontaneous and neutron induced fission with reference to the data needs for reactor applications oriented towards actinide burner studies. The specific topics covered are the following: experimental measurements and theoretical predictions and evaluations of fission neutron energy spectra, average prompt fission neutron multiplicity, correlation in neutron emission from complementary fragments, neutron emission during acceleration of fission fragments, statistical properties of neutron rich nuclei by study of emission spectra of neutrons from the excited fission fragments, integral qualification of nu-bar for the major fissile isotopes, nu-bar total of 239Pu and 235U, and related problems. Refs figs and tabs

  1. The neutron and gamma-ray dose characterization using the Monte Carlo method to study the feasibility of the Prompt Gamma Activation Analysis technique at IPR-R1 TRIGA reactor in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Guerra, Bruno T.; Soares, Alexandre L.; Grynberg, Suely E.; Menezes, Maria Angela B.C., E-mail: brunoteixeiraguerra@yahoo.com.br, E-mail: menezes@cdtn.br, E-mail: asleal@cdtn.br, E-mail: seg@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    The IPR-R1 is a reactor type TRIGA, Mark-I model, manufactured by the General Atomic Company and installed at Nuclear Technology Development Centre (CDTN) of Brazilian Nuclear Energy Commission (CNEN), in Belo Horizonte, Brazil. It is a light water moderated and cooled, graphite-reflected, open-pool type research reactor. IPR-R1 works at 100 kW but it will be briefly licensed to operate at 250 kW. It presents low power, low pressure, for application in research, training and radioisotopes production. The fuel is an alloy of zirconium hydride and uranium enriched at 20% in {sup 235}U. The Implementation of the PGNAA (Prompt Gamma Neutron Activation Analysis) Technical at the TRIGA IPR-R1 research reactor of the CDTN will significantly increase in the types of matrices analyzable. A project is underway in order to implement this technique in CDTN. In order of verified the feasibility of the PGNAA at the TRIGA reactor, the MCNP (Monte Carlo N-Particle) method is used to theoretical calculations. This paper presents the results of a preliminary study of the neutron and gamma-ray dose in the room where the reactor is located, in case of implementation of this technique in the IPR-R1. (author)

  2. Measurements of neutron-induced capture and fission reactions on $^{235}$ U: cross sections and ${\\alpha}$ ratios, photon strength functions and prompt ${\\gamma}$-ray from fission

    CERN Multimedia

    We propose to measure the neutron-induced capture cross section of the fissile isotope $^{235}$U using a fission tagging set-up. This new set-up has been tested successfully in 2010 and combines the n_TOF 4${\\pi}$ Total Absorption Calorimeter (TAC) with MicroMegas (MGAS) fission detectors. It has been proven that such a combination of detectors allows distinguishing with very good reliability the electromagnetic cascades from the capture reactions from dominant ${\\gamma}$-ray background coming from the fission reactions. The accurate discrimination of the fission background is the main challenge in the neutron capture cross section measurements of fissile isotopes. The main results from the measurement will be the associated capture cross section and ${\\alpha}$ ratio in the resolved (0.3-2250 eV) and unresolved (2.25-30 keV) resonance regions. According to the international benchmarks and as it is mentioned in the NEA High Priority Request List (HPRL), the 235U(n,${\\gamma}$) cross section is of utmost impo...

  3. Late Time Emission of Prompt Fission Gamma Rays

    CERN Document Server

    Talou, P; Stetcu, I; Lestone, J P; McKigney, E; Chadwick, M B

    2016-01-01

    The emission of prompt fission $\\gamma$ rays within a few nanoseconds to a few microseconds following the scission point is studied in the Hauser-Feshbach formalism applied to the deexcitation of primary excited fission fragments. Neutron and $\\gamma$-ray evaporations from fully accelerated fission fragments are calculated in competition at each stage of the decay, and the role of isomers in the fission products, before $\\beta$-decay, is analyzed. The time evolution of the average total $\\gamma$-ray energy, average total $\\gamma$-ray multiplicity, and fragment-specific $\\gamma$-ray spectra, is presented in the case of neutron-induced fission reactions of $^{235}$U and $^{239}$Pu, as well as spontaneous fission of $^{252}$Cf. The production of specific isomeric states is calculated and compared to available experimental data. About 7% of all prompt fission $\\gamma$ rays are predicted to be emitted between 10 nsec and 5 $\\mu$sec following fission, in the case of $^{235}$U and $^{239}$Pu $(n_{\\rm th},f)$ reactio...

  4. Neutron capture and fission reactions on 235U: cross sections, α-ratios and prompt γ-ray emission from fission

    Directory of Open Access Journals (Sweden)

    González-Romero E.

    2013-03-01

    Full Text Available According to the international benchmarks, and as it is mentioned in the NEA High Priority Request List, the 235U(n,γ cross section is of utmost importance for the operation and design of current and advanced nuclear reactors. The required accuracy in this energy region (100 eV to 2.25 keV ranges between 5% and 7%, to be compared with the present differences of 20% between the α-ratios in different evaluations. At n_TOF we have measured this cross section during the summer of 2012 using a fission tagging capture set-up. This new set-up has been tested successfully in 2010 and combines the n_TOF 4π Total Absorption Calorimeter with a series of MicroMegas fission detectors. The experiment has provided as well very valuable information on the distribution of energies and multiplicities of the γ-rays emitted prompt after capture and fission reactions. The very fresh data from this experiment will be presented for the first time, and their quality and expected results will be discussed in detail

  5. SU-E-J-100: Reconstruction of Prompt Gamma Ray Three Dimensional SPECT Image From Boron Neutron Capture Therapy(BNCT)

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, D; Jung, J; Suh, T [The Catholic University of Korea, College of medicine, Department of biomedical engineering (Korea, Republic of)

    2014-06-01

    Purpose: Purpose of paper is to confirm the feasibility of acquisition of three dimensional single photon emission computed tomography (SPECT) image from boron neutron capture therapy (BNCT) using Monte Carlo simulation. Methods: In case of simulation, the pixelated SPECT detector, collimator and phantom were simulated using Monte Carlo n particle extended (MCNPX) simulation tool. A thermal neutron source (<1 eV) was used to react with the boron uptake region (BUR) in the phantom. Each geometry had a spherical pattern, and three different BURs (A, B and C region, density: 2.08 g/cm3) were located in the middle of the brain phantom. The data from 128 projections for each sorting process were used to achieve image reconstruction. The ordered subset expectation maximization (OSEM) reconstruction algorithm was used to obtain a tomographic image with eight subsets and five iterations. The receiver operating characteristic (ROC) curve analysis was used to evaluate the geometric accuracy of reconstructed image. Results: The OSEM image was compared with the original phantom pattern image. The area under the curve (AUC) was calculated as the gross area under each ROC curve. The three calculated AUC values were 0.738 (A region), 0.623 (B region), and 0.817 (C region). The differences between length of centers of two boron regions and distance of maximum count points were 0.3 cm, 1.6 cm and 1.4 cm. Conclusion: The possibility of extracting a 3D BNCT SPECT image was confirmed using the Monte Carlo simulation and OSEM algorithm. The prospects for obtaining an actual BNCT SPECT image were estimated from the quality of the simulated image and the simulation conditions. When multiple tumor region should be treated using the BNCT, a reasonable model to determine how many useful images can be obtained from the SPECT could be provided to the BNCT facilities. This research was supported by the Leading Foreign Research Institute Recruitment Program through the National Research

  6. SU-E-J-100: Reconstruction of Prompt Gamma Ray Three Dimensional SPECT Image From Boron Neutron Capture Therapy(BNCT)

    International Nuclear Information System (INIS)

    Purpose: Purpose of paper is to confirm the feasibility of acquisition of three dimensional single photon emission computed tomography (SPECT) image from boron neutron capture therapy (BNCT) using Monte Carlo simulation. Methods: In case of simulation, the pixelated SPECT detector, collimator and phantom were simulated using Monte Carlo n particle extended (MCNPX) simulation tool. A thermal neutron source (<1 eV) was used to react with the boron uptake region (BUR) in the phantom. Each geometry had a spherical pattern, and three different BURs (A, B and C region, density: 2.08 g/cm3) were located in the middle of the brain phantom. The data from 128 projections for each sorting process were used to achieve image reconstruction. The ordered subset expectation maximization (OSEM) reconstruction algorithm was used to obtain a tomographic image with eight subsets and five iterations. The receiver operating characteristic (ROC) curve analysis was used to evaluate the geometric accuracy of reconstructed image. Results: The OSEM image was compared with the original phantom pattern image. The area under the curve (AUC) was calculated as the gross area under each ROC curve. The three calculated AUC values were 0.738 (A region), 0.623 (B region), and 0.817 (C region). The differences between length of centers of two boron regions and distance of maximum count points were 0.3 cm, 1.6 cm and 1.4 cm. Conclusion: The possibility of extracting a 3D BNCT SPECT image was confirmed using the Monte Carlo simulation and OSEM algorithm. The prospects for obtaining an actual BNCT SPECT image were estimated from the quality of the simulated image and the simulation conditions. When multiple tumor region should be treated using the BNCT, a reasonable model to determine how many useful images can be obtained from the SPECT could be provided to the BNCT facilities. This research was supported by the Leading Foreign Research Institute Recruitment Program through the National Research

  7. Theory of neutron emission in fission

    International Nuclear Information System (INIS)

    Following a summary of the observables in neutron emission in fission, a brief history is given of theoretical representations of the prompt fission neutron spectrum N(E) and average prompt neutron multiplicity bar νp. This is followed by descriptions, together with examples, of modern approaches to the calculation of these quantities including recent advancements. Emphasis will be placed upon the predictability and accuracy of the modern approaches. In particular, the dependence of N(E) and bar νp on the fissioning nucleus and its excitation energy will be discussed, as will the effects of and competition between first-, second- and third-chance fission in circumstances of high excitation energy. Finally, properties of neutron-rich (fission-fragment) nuclei are discussed that must be better known to calculate N(E) and bar νp with higher accuracy than is currently possible

  8. Prompt radiation detectors to monitor target conditions

    DEFF Research Database (Denmark)

    Barnhart, T. E.; Engle, J. W.; Valdovinos, H. F.;

    2012-01-01

    Lessons learned by basic scientists in the study of experimental nuclear physics can often go unnoticed by cyclotron operator’s intent on meeting a demanding schedule of tracer production. Prompt neutrons and gammas are the signature that the desired reaction is occurring, providing a robust meas...

  9. Prompt radiation detectors to monitor target conditions

    DEFF Research Database (Denmark)

    Barnhart, T. E.; Engle, J. W.; Valdovinos, H. F.;

    2012-01-01

    Lessons learned by basic scientists in the study of experimental nuclear physics can often go unnoticed by cyclotron operator’s intent on meeting a demanding schedule of tracer production. Prompt neutrons and gammas are the signature that the desired reaction is occurring, providing a robust...

  10. Prompt γ-rays emitted in fission of 226Ra by 12 MeV protons

    International Nuclear Information System (INIS)

    The total energy associated with the emission of prompt γ-rays in fission of 226Ra induced by 12 MeV protons was measured in correlation with the fragment mass and kinetic energy. The dependence of the average total γ-ray energy on fragment mass and total kinetic energy resembles the corresponding dependence of the average number of neutrons. Using these results and the results for the average number of neutrons, the excitation energy of the fragments at the scission point was calculated. The results support the view that the scission-point configuration for the symmetric fission mode is more elongated than that for the asymmetric mode. (B.G.)

  11. Estimation of total as well as bioaccessible levels and average daily dietary intake of iodine from Japanese edible seaweeds by epithermal neutron activation analysis

    International Nuclear Information System (INIS)

    An epi-thermal instrumental neutron activation analysis (EINAA) method in conjunction with Compton suppression spectrometry (EINAA-CSS) was used for the determination of total iodine in eight different species of edible seaweeds from Japan. This method gave an absolute detection limit of about 2 μg. The accuracy of the method was evaluated using various reference materials and found to be generally in agreement within ±6% of the certified values. The longitudinal distributions of iodine at different growing stages in Japanese sea mustard and tangle seaweeds were investigated. For a 150-cm-high tangle, the highest concentration (5,360 mg/kg) of iodine was found at the root, then decreased slowly to 780 mg/kg in the middle portion (60-75 cm), and increased to 2,300 mg/kg at the apex. On the other hand, for a 190-cm-high sea mustard the highest levels of iodine were found both at the roots (164 mg/kg) and apex (152 mg/kg) with lower values (98 mg/kg) in the middle section. In order to estimate the bioaccessible fraction of iodine, seaweeds were digested by an in vitro enzymolysis method, dietary fibre separated from residue, and both fractions analyzed by EINAA-CSS. The average daily dietary intakes of total (0.14 mg) as well as bioaccessible fraction (0.12 mg) of iodine from the consumption of sea mustards were estimated. (author)

  12. Evaluation of the photo-neutron source and delayed neutrons in the Syrian miniature neutron source reactor

    International Nuclear Information System (INIS)

    A mathematical model has been developed to simulate the dynamic behavior of the Syrian Miniature Neutron Source Reactor (MNSR). The model is used to assess and evaluate the core average temperature as a function of the overall reactivity load in the core on one hand. On the other hand, the model is utilized to evaluate dynamically the photo and delayed neutron effects in MNSR. The model considers relevant physical phenomena that govern the core such as reactor kinetics, reactivity feedbacks due to coolant temperature and xenon, and thermalhydraulics. Natural convection and point kinetics including the prompt jump and complete mixing approximations were employed. Peak power, reactivity core load, core outlet temperature, and other variables are predicted during self-limiting power excursions. Direct photo-neutron sources strength was dynamically evaluated for the MNSR in subcritical condition. Two different static methods were applied for comparison. In addition, measurement of the photo-neutron source was made using neutron flux monitors and neutron activation analysis technique. Results for both methods were in good agreement. Dynamics effect of the photo neutron source on reactor response to reactivity insertions was demonstrated. Photo-neutron source existence due to beryllium reflector was realized. Compared to related references, close results have been obtained. Core average temperature was studied as a function of reactivity during reactor operation and transients. An overall rough estimate of core average temperature as a function of reactivity load is presented; hence, a procedure to measure such temperature is suggested. (author)

  13. Future research program on prompt γ-ray emission in nuclear fission

    Science.gov (United States)

    Oberstedt, S.; Billnert, R.; Hambsch, F.-J.; Lebois, M.; Oberstedt, A.; Wilson, J. N.

    2015-12-01

    In recent years the measurement of prompt fission γ-ray spectra (PFGS) has gained renewed interest, after about forty years since the first comprehensive studies of the reactions 235U(n th , f), 239Pu(n th ,f) and 252Cf(sf). The renaissance was initiated by requests for new values especially for γ-ray multiplicity and average total energy release per fission in neutron-induced fission of 235U and 239Pu. Both isotopes are considered the most important ones with respect to the modeling of innovative cores required for the Generation-IV reactors, the majority working with fast neutrons. During the last 5 years we have conducted a systematic study of spectral data for thermal-neutron-induced fission on 235U and 241Pu as well as for the spontaneous fission of 252Cf with unprecedented accuracy. From the new data we conclude that those reactions do not considerably contribute to the observed heat excess and suspect other reactions playing a significant role. Possible contributions may originate from fast-neutron-induced reactions on 238U, which is largely present in the fuel, or from γ-induced fission from neutron capture in the construction material. A first experiment campaign on prompt γ-ray emission from fast-neutron-induced fission on 235,238U was successfully performed in order to test our assumptions. In the following we attempt to summarize, what has been done in the field to date, and to motivate future measurement campaigns exploiting dedicated neutron and photon beams as well as upcoming highly efficient detector assemblies.

  14. Future research program on prompt γ-ray emission in nuclear fission

    Energy Technology Data Exchange (ETDEWEB)

    Oberstedt, S.; Hambsch, F.J. [Joint Research Centre IRMM, European Commission, Geel (Belgium); Billnert, R. [Joint Research Centre IRMM, European Commission, Geel (Belgium); Chalmers Tekniska Hoegskola, Fundamental Fysik, Goeteborg (Sweden); Lebois, M.; Wilson, J.N. [Institut de Physique Nucleaire Orsay, Orsay (France); Oberstedt, A. [Chalmers Tekniska Hoegskola, Fundamental Fysik, Goeteborg (Sweden); Ossolution Consulting, Oerebro (Sweden)

    2015-12-15

    In recent years the measurement of prompt fission γ-ray spectra (PFGS) has gained renewed interest, after about forty years since the first comprehensive studies of the reactions {sup 235}U(n{sub th}, f), {sup 239}Pu(n{sub th},f) and {sup 252}Cf(sf). The renaissance was initiated by requests for new values especially for γ-ray multiplicity and average total energy release per fission in neutron-induced fission of {sup 235}U and {sup 239}Pu. Both isotopes are considered the most important ones with respect to the modeling of innovative cores required for the Generation-IV reactors, the majority working with fast neutrons. During the last 5 years we have conducted a systematic study of spectral data for thermal-neutron-induced fission on {sup 235}U and {sup 241}Pu as well as for the spontaneous fission of {sup 252}Cf with unprecedented accuracy. From the new data we conclude that those reactions do not considerably contribute to the observed heat excess and suspect other reactions playing a significant role. Possible contributions may originate from fast-neutron-induced reactions on {sup 238}U, which is largely present in the fuel, or from γ-induced fission from neutron capture in the construction material. A first experiment campaign on prompt γ-ray emission from fast-neutron-induced fission on {sup 235,238}U was successfully performed in order to test our assumptions. In the following we attempt to summarize, what has been done in the field to date, and to motivate future measurement campaigns exploiting dedicated neutron and photon beams as well as upcoming highly efficient detector assemblies. (orig.)

  15. Promptness and Academic Performance

    OpenAIRE

    Novarese, Marco; Di Giovinazzo, Viviana

    2013-01-01

    This article uses university administration data to investigate the relation between student behavior (rapid response in finalizing enrolment procedures) and academic performance. It shows how student promptness in enrolling, or lack of it, can prove a useful forecast of academic success. Several explanations can be given, including simply the greater or lesser tendency to procrastinate.

  16. Prompt fission γ -ray spectrum characteristics from 240Pu(sf ) and 242Pu(sf )

    Science.gov (United States)

    Oberstedt, S.; Oberstedt, A.; Gatera, A.; Göök, A.; Hambsch, F.-J.; Moens, A.; Sibbens, G.; Vanleeuw, D.; Vidali, M.

    2016-05-01

    In this paper we present first results for prompt fission γ -ray spectra (PFGS) characteristics from the spontaneous fission (sf) of 240Pu and 242Pu. For 242Pu(sf ) we obtained, after proper unfolding of the detector response, an average energy per photon ɛ¯γ=(0.843 ±0.012 ) MeV, an average multiplicity M¯γ=(6.72 ±0.07 ) , and an average total γ -ray energy release per fission E¯γ ,tot = (5.66 ± 0.06) MeV. The 240Pu(sf ) emission spectrum was obtained by applying a so-called detector-response transformation function determined from the 242Pu spectrum measured in exactly the same geometry. The results are an average energy per photon ɛ¯γ=(0.80 ±0.07 ) MeV, the average multiplicity M¯γ = (8.2 ± 0.4), and an average total γ -ray energy release per fission E¯γ ,tot = (6.6 ± 0.5) MeV. The PFGS characteristics for 242Pu(sf ) are in very good agreement with those from thermal-neutron-induced fission on 241Pu and scales well with the corresponding prompt neutron multiplicity. Our results in the case of 240Pu(sf ), although drawn from a limited number of events, show a significantly enhanced average multiplicity and average total energy, but may be understood from a different fragment yield distribution in 240Pu(sf ) compared to that of 242Pu(sf ).

  17. Prompt Fission Gamma-ray Studies at DANCE

    Science.gov (United States)

    Jandel, M.; Rusev, G.; Bond, E. M.; Bredeweg, T. A.; Chadwick, M. B.; Couture, A.; Fowler, M. M.; Haight, R. C.; Kawano, T.; Keksis, A. L.; Mosby, S. M.; O'Donnell, J. M.; Rundberg, R. S.; Stetcu, I.; Talou, P.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Stoyer, M. A.; Haslett, R. J.; Henderson, R. A.; Becker, J. A.; Wu, C. Y.

    Measurements of correlated data on prompt-fission γ-rays (PFG) have been carried out for various actinide isotopes in recent years using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory (LANL). We have developed a model that conveniently parametrizes the correlated data of γ-ray multiplicity and energy. New results on two- dimensional prompt-fission γ-ray multiplicity versus energy distributions from spontaneous fission on 252Cf and neutron-induced fission on 242mAm are presented together with previously obtained results on 233,235U and 239Pu. Correlated PFG data from 252Cf are also compared to results of the detailed theoretical model developed at LANL, for different thresholds of PFG energies. Future plans to measure correlated data on fission fragments, prompt fission neutrons and γ-rays at DANCE are presented.

  18. State Averages

    Data.gov (United States)

    U.S. Department of Health & Human Services — A list of a variety of averages for each state or territory as well as the national average, including each quality measure, staffing, fine amount and number of...

  19. Properties of neutron sources

    International Nuclear Information System (INIS)

    The Conference presentations were divided into sessions devoted to the following topics: white neutron sources, primarily pulsed (6 papers); fast neutron fields (5 papers); Californium-252 prompt fission neutron spectra (14 papers); monoenergetic sources and filtered beams (11 papers); 14 MeV neutron sources (10 papers); selected special application (one paper); and a general interest session (4 papers). Individual abstracts were prepared separately for the papers

  20. Prompting Designers to Design

    DEFF Research Database (Denmark)

    Ahmed, Saeema

    2007-01-01

    to prompt designers with their design queries. A method that automatically extracts relationships between concepts is described, along with some examples. The method can be implemented as part of knowledge management system and the relationships are extracted form documents that are indexed within...... the system. The distinctive features of this approach is that all the concepts are elicited from the minds of engineering designers, and the system builds up knowledge as more documents enter the system. The approach is based on an understanding obtained from a number of empirical studies and also from...

  1. Quaternion Averaging

    Science.gov (United States)

    Markley, F. Landis; Cheng, Yang; Crassidis, John L.; Oshman, Yaakov

    2007-01-01

    Many applications require an algorithm that averages quaternions in an optimal manner. For example, when combining the quaternion outputs of multiple star trackers having this output capability, it is desirable to properly average the quaternions without recomputing the attitude from the the raw star tracker data. Other applications requiring some sort of optimal quaternion averaging include particle filtering and multiple-model adaptive estimation, where weighted quaternions are used to determine the quaternion estimate. For spacecraft attitude estimation applications, derives an optimal averaging scheme to compute the average of a set of weighted attitude matrices using the singular value decomposition method. Focusing on a 4-dimensional quaternion Gaussian distribution on the unit hypersphere, provides an approach to computing the average quaternion by minimizing a quaternion cost function that is equivalent to the attitude matrix cost function Motivated by and extending its results, this Note derives an algorithm that deterniines an optimal average quaternion from a set of scalar- or matrix-weighted quaternions. Rirthermore, a sufficient condition for the uniqueness of the average quaternion, and the equivalence of the mininiization problem, stated herein, to maximum likelihood estimation, are shown.

  2. Prompting Designers to Design

    DEFF Research Database (Denmark)

    Ahmed, Saeema

    2006-01-01

    Recent research suggest that engineering designers need assistance to understand what information is relevant for their particular design problem. They require guidance in formulating their queries and also to understand what information is relevant for them. This paper presents an approach to...... prompt designers with their design queries. A method that automatically extracts relationships between concepts is described, along with some examples. The method can be implemented as part of knowledge management system and the relationships are extracted form documents that are indexed within the...... system. The distinctive features of this approach is that all the concepts are elicited from the minds of engineering designers, and the system builds up knowledge as more documents enter the system. The approach is based on an understanding obtained from a number of empirical studies and also from...

  3. On uncertainties and fluctuations of averaged neutron cross sections in unresolved resonance energy region for 235U, 238U, 239Pu

    International Nuclear Information System (INIS)

    This paper analyses the reasons for the differences which exist between group-averaged evaluated cross-section data from different evaluated data files for U235, U238 and Pu239 in the unresolved resonance energy region. (author)

  4. 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)

  5. Neutron Thermal Cross Sections, Westcott Factors, Resonance Integrals, Maxwellian Averaged Cross Sections and Astrophysical Reaction Rates Calculated from the ENDF/B-VII.1, JEFF-3.1.2, JENDL-4.0, ROSFOND-2010, CENDL-3.1 and EAF-2010 Evaluated Data Libraries

    Science.gov (United States)

    Pritychenko, B.; Mughabghab, S. F.

    2012-12-01

    We present calculations of neutron thermal cross sections, Westcott factors, resonance integrals, Maxwellian-averaged cross sections and astrophysical reaction rates for 843 ENDF materials using data from the major evaluated nuclear libraries and European activation file. Extensive analysis of newly-evaluated neutron reaction cross sections, neutron covariances, and improvements in data processing techniques motivated us to calculate nuclear industry and neutron physics quantities, produce s-process Maxwellian-averaged cross sections and astrophysical reaction rates, systematically calculate uncertainties, and provide additional insights on currently available neutron-induced reaction data. Nuclear reaction calculations are discussed and new results are presented. Due to space limitations, the present paper contains only calculated Maxwellian-averaged cross sections and their uncertainties. The complete data sets for all results are published in the Brookhaven National Laboratory report.

  6. Neutronic measurements of radioactive waste

    International Nuclear Information System (INIS)

    This document presents the general matters involved in the radioactive waste management and the different non destructive assays of radioactivity. The neutronic measurements used in the characterization of waste drums containing emitters are described with more details, especially the active neutronic interrogation assays with prompt or delayed neutron detection: physical principle, signal processing and evaluation of the detection limit. (author)

  7. Even–odd effects in prompt emission of spontaneously fissioning even–even Pu isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Tudora, A., E-mail: anabellatudora@hotmail.com [University of Bucharest, Faculty of Physics, Bucharest Magurele, POB MG-11, R-76900 (Romania); Hambsch, F.-J. [EC-JRC Institute for Reference Materials and Measurements (IRMM), Retieseweg 111, B-2440, Geel (Belgium); Giubega, G.; Visan, I. [University of Bucharest, Faculty of Physics, Bucharest Magurele, POB MG-11, R-76900 (Romania)

    2015-01-15

    The available experimental Y(A,TKE) data for {sup 236,238,240,242,244}Pu(SF) together with the Zp model prescription with appropriate parameters allows the investigation of even–odd effects in fragment distributions. The size of the global even–odd effect in Y(Z) is decreasing from {sup 244}Pu(SF) to {sup 236}Pu(SF) confirming the general observation of a decrease of the even–odd effect with the fissility parameter. Charge polarizations (ΔZ) and root-mean squares (rms) as a function of A of {sup 236–244}Pu(SF) were obtained for the first time. In the asymmetric fission region both ΔZ(A) and rms(A) exhibit oscillations with a periodicity of about 5 mass units due to the even–odd effects. The total average charge deviations 〈ΔZ〉 (obtained by averaging ΔZ(A) over the experimental Y(A) distribution) are of about |0.5| for all studied Pu(SF) systems. The comparison of the calculated ΔZ(A) and rms(A) of {sup 240}Pu(SF) with those of {sup 239}Pu(n{sub th},f) reported by Wahl shows an in-phase oscillation with a higher amplitude in the case of {sup 240}Pu(SF), confirming the higher even–odd effect in the case of SF. As in the previously studied cases ({sup 233,235}U(n{sub th},f), {sup 239}Pu(n{sub th},f), {sup 252}Cf(SF)) the even–odd effects in the prompt emission of {sup 236–244}Pu(SF) are mainly due to the Z even–odd effects in fragment distributions and charge polarizations and the N even–odd effects in the average neutron separation energies from fragments 〈Sn〉. The size of the global N even–odd effect in 〈Sn〉 is decreasing with the fissility parameter, being higher for the Pu(SF) systems compared to the previously studied systems. The prompt neutron multiplicities as a function of Z, ν(Z), exhibit sawtooth shapes with a visible staggering for asymmetric fragmentations. The size of the global Z even–odd effect in ν(Z) exhibits a decreasing trend with increasing fissility. The average prompt neutron multiplicities as a

  8. Total prompt γ-ray emission in fission

    Science.gov (United States)

    Wu, C. Y.; Chyzh, A.; Kwan, E.; Henserson, R. A.; Bredeweg, T. A.; Haight, R. C.; Hayes-Sterbenz, A. C.; Lee, H. Y.; O'Donnell, J. M.; Ullmann, J. L.

    2016-06-01

    The total prompt γ-ray energy distributions for the neutron-induced fission of 235U, 239,241Pu at incident neutron energy of 0.025 eV ‒ 100 keV, and the spontaneous fission of 252Cf were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) array in coincidence with the detection of fission fragments by a parallel-plate avalanche counter. DANCE is a highly segmented, highly efficient 4π γ-ray calorimeter. Corrections were made to the measured distribution by unfolding the two-dimension spectrum of total γ-ray energy vs multiplicity using a simulated DANCE response matrix. The mean values of the total prompt γ-ray energy, determined from the unfolded distributions, are ~ 20% higher than those derived from measurements using single γ-ray detector for all the fissile nuclei studied. This raises serious concern on the validity of the mean total prompt γ-ray energy obtained from the product of mean values for both prompt γ-ray energy and multiplicity.

  9. Xenon diffusion studies with prompt gamma activation analysis

    International Nuclear Information System (INIS)

    Developing a better understanding of xenon transport through porous systems is critical to predicting how this gas will enter the atmosphere after a below ground nuclear weapons test. Radioxenon monitoring is a vital part of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System. This work details the development of prompt gamma activation analysis for measuring the diffusion rates of xenon and argon gases through a porous medium. The University of Texas at Austin maintains a prompt gamma activation analysis facility with a peak neutron flux of ∼ 1.5 x 107 cm-2 s-1 and a beam diameter of 1 cm. Due to the relatively large prompt gamma cross sections of many stable xenon isotopes at thermal and sub-thermal neutron energies, prompt gamma activation analysis is a suitable technique for in situ non-destructive analysis of natural xenon. A test chamber has been designed and constructed to utilize prompt gamma activation analysis to measure xenon and argon diffusion through geological materials (e.g., sand, soil, etc.). Initial experiments have been conducted to determine the detection limits for stable gas measurements. The results from these experiments will be utilized to benchmark parts of a xenon transport model that is being used to determine diffusion coefficients for xenon and argon. (author)

  10. Low energy prompt gamma-ray tests of a large volume BGO detector

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A., E-mail: aanaqvi@kfupm.edu.sa [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Kalakada, Zameer [Department of Civil Engineering, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Al-Anezi, M.S.; Raashid, M.; Khateeb-ur-Rehman [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Maslehuddin, M. [Center for Engineering Research, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Garwan, M.A. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)

    2012-01-15

    Tests of a large volume Bismuth Germinate (BGO) detector were carried out to detect low energy prompt gamma-rays from boron and cadmium-contaminated water samples using a portable neutron generator-based Prompt Gamma Neutron Activation Analysis (PGNAA) setup. Inspite of strong interference between the sample- and the detector-associated prompt gamma-rays, an excellent agreement has been observed between the experimental and calculated yields of the prompt gamma-rays, indicating successful application of the large volume BGO detector in the PGNAA analysis of bulk samples using low energy prompt gamma-rays. - Highlights: Black-Right-Pointing-Pointer Performance tests of a portable neutron generator based PGNAA setup for field measurement. Black-Right-Pointing-Pointer Application of large volume BGO detector in prompt gamma analysis of bulk samples utilizing low energy prompt-gamma rays. Black-Right-Pointing-Pointer Study of interference of boron and cadmium prompt gamma-rays from bulk samples with BGO detector background spectrum.

  11. Focusing cold neutrons using capillary optics for analytical nuclear methods

    International Nuclear Information System (INIS)

    The authors demonstrate improved detection limits and lateral resolution for prompt gamma activation analysis (PGAA) by using a neutron focusing device to increase the neutron intensity. The neutron lens, made of glass fibers with hollow polycapillaries, was designed and constructed by X-Ray Optical Systems, Inc. It has been characterized and used for preliminary experiments at the PGAA station of the Cold Neutron Research Facility (CNRF) at NIST. The lens accepts a polychromatic cold neutron beam (wavelengths longer than 0.4 run) from a neutron guide 50 mm x 45 mm in cross section, and delivers a focused beam of 0.5 mm in diameter (full width at half maximum) at 52 mm from the exit of the capillaries. The average neutron current density at the focus within the FWHM is 80 times higher than that of the direct incident beam. Test samples of 2% gadolinium glass particles of size about 0.1 to 0.2 mm, and cylindrical glass samples of 0.5 mm and 1 mm in diameter containing 15 % boron have been scanned across the focal plane to determine the spatial response as well as the peak count rate. Results from both sets of measurements show promise for higher detection sensitivity on small samples, and for two-dimensional mapping of samples with lateral compositional variation. Problems associated with neutron background will be addressed

  12. Measurement of subcriticality using delayed neutron source combined with pulsed neutron accelerator

    International Nuclear Information System (INIS)

    A new experimental method for subcriticality measurement was developed by using delayed neutron source which is produced by external pulsed neutron source to increase accuracy of measured results by overcoming the space dependency problem which means difference of measured results in different detector position and often appeared in almost all other subcriticality measurement techniques. Experiments were performed at Kyoto University Critical Assembly (KUCA) combined with a DT accelerator to produce pulsed neutron in outside of the core repeatedly. In this method, neutron detection counts in the prompt neutron time region which are appeared just after injection of pulsed neutron are omitted, whereas neutron counts in the delayed neutron time region which are appeared after disappearance of exponential decay of the prompt neutron are adopted in analysis based on neutron source multiplication method or neutron noise analysis method; the variance to mean ratio method. In the delayed neutron time region, neutron sources to initiate fission chain reactions in subcritical state are delayed neutrons from delayed neutron precursors which are mainly produced by fission chain reactions in the prompt neutron time region, and delayed neutron precursors exist only in the fuel region, which makes possible to decrease the space dependency problem. The obtained results were compared with conventional pulsed neutron method, and it was found that the space dependency problem in subcriticality measurement can be fairly decreased by using the present new method compared with conventional one. (author)

  13. PGNAA neutron source moderation setup optimization

    OpenAIRE

    Zhang, Jinzhao; Tuo, Xianguo

    2013-01-01

    Monte Carlo simulations were carried out to design a prompt {\\gamma}-ray neutron activation analysis (PGNAA) thermal neutron output setup using MCNP5 computer code. In these simulations the moderator materials, reflective materials and structure of the PGNAA 252Cf neutrons of thermal neutron output setup were optimized. Results of the calcuations revealed that the thin layer paraffin and the thick layer of heavy water moderated effect is best for 252Cf neutrons spectrum. The new design compar...

  14. PGNAA neutron source moderation setup optimization

    CERN Document Server

    Zhang, Jinzhao

    2013-01-01

    Monte Carlo simulations were carried out to design a prompt {\\gamma}-ray neutron activation analysis (PGNAA) thermal neutron output setup using MCNP5 computer code. In these simulations the moderator materials, reflective materials and structure of the PGNAA 252Cf neutrons of thermal neutron output setup were optimized. Results of the calcuations revealed that the thin layer paraffin and the thick layer of heavy water moderated effect is best for 252Cf neutrons spectrum. The new design compared with the conventional neutron source design, the thermal neutron flux and rate were increased by 3.02 times and 3.27 times. Results indicate that the use of this design should increase the neutron flux of prompt gamma-ray neutron activation analysis significantly.

  15. Application of neutron noise analysis to a swimming pool research reactor

    International Nuclear Information System (INIS)

    This work is part of a programme of establishing practical applications of neutron noise techniques to a swimming pool research reactor and deals with two different items: (1) The identification of local boiling caused e.g. by a partial blockage of the coolant flow in a fuel element. Local boiling can easily lead to a burn-out situation. The onset of boiling can be detected by neutron noise analysis and a boiling detection system is presently under development. (2) The measurement of the time evolution of the reactivity induced by xenon after reactor shut-down by an on-line reactivity meter based on neutron noise analysis. From the data, the prompt neutron decay constant at delayed critical, the equilibrium xenon reactivity worth, and an estimate of the average steady-state power flux in the core before reactor shut-down were obtained. (author)

  16. Prompt gamma-ray analysis of chlorine in superpozz cement concrete

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A., E-mail: aanaqvi@kfupm.edu.sa [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Kalakada, Zameer [Department of Civil Engineering, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Al-Matouq, Faris A. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Maslehuddin, M. [Center for Engineering Research, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Al-Amoudi, O.S.B. [Department of Civil Engineering, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Ur-Rehman, Khateeb [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)

    2012-11-21

    The chlorine concentration in Superpozz (SPZ) cement concrete was analyzed using a newly designed prompt gamma-ray neutron activation (PGNAA) setup utilizing a portable neutron generator. The setup, which mainly consists of a neutron source along with its moderator placed side by side with a shielded gamma-ray detector, allows determining chloride concentration in a concrete structure from one side. The setup has been tested through chlorine detection in chloride-contaminated Superpozz (SPZ) cement concrete specimens using 6.11 and 2.86{+-}3.10 MeV chlorine prompt gamma-rays. The optimum 0.032{+-}0.012 wt% value of Minimum Detectable Concentration (MDC) of chlorine in SPZ cement concrete measured in this study shows a successful application of a portable neutron generator in chloride analysis of concrete structure for corrosion studies.

  17. Neutron scattering studies in the actinide region

    International Nuclear Information System (INIS)

    During the report period we have investigated the following areas: Neutron elastic and inelastic scattering measurements on 14N, 181Ta, 232Th, 238U and 239Pu; Prompt fission spectra for 232Th, 235U, 238U and 239Pu; Theoretical studies of neutron scattering; Neutron filters; New detector systems; and Upgrading of neutron target assembly, data acquisition system, and accelerator/beam-line apparatus

  18. Fission neutrons experiments, evaluation, modeling and open problems

    CERN Document Server

    Kornilov, Nikolay

    2014-01-01

    Although the fission of heavy nuclei was discovered over 75 years ago, many problems and questions still remain to be addressed and answered. The reader will be presented with an old, but persistent problem of this field: The contradiction between Prompt Fission Neutron (PFN) spectra measured with differential (microscopic) experiments and integral (macroscopic and benchmark) experiments (the Micro-Macro problem). The difference in average energy is rather small ~3% but it is stable and we cannot explain the difference due to experimental uncertainties. Can we measure the PFN spectrum with hig

  19. Development of a CdTe thermal neutron detector for neutron imaging

    International Nuclear Information System (INIS)

    A thin CdTe thermal neutron detector has been developed and its suitability for neutron imaging has been investigated. Simulations of the interaction of neutrons with a 0.5 mm-thick CdTe detector demonstrate the advantages of using 96 keV prompt gamma rays produced by neutron capture in 113Cd as a neutron event. Specifically, they provide a high spatial resolution and approximately the same detection efficiency as 558 keV prompt gamma rays, which are commonly used for detecting thermal neutrons in CdTe detectors. We fabricated a thin CdTe detector. Measurements using a 133Ba gamma-ray source revealed that the detector has a gamma-ray energy resolution of 3 keV at 80 keV, while measurements using a 252Cf neutron source demonstrated that the CdTe detector has good neutron/gamma ray discrimination.

  20. Basic neutronics. Neutrons migration

    International Nuclear Information System (INIS)

    This article presents the basic neutronics necessary for the understanding of the operation of the different types of nuclear reactors: 1 - introduction to neutronics: principle of fission chain reactions, fast neutron reactors and thermal neutron reactors, capture, neutron status, variations with the reactor lattices; 2 - Boltzmann equation: neutrons population, neutrons migration, characterization of neutrons population and reactions, integral form of the Boltzmann equation, integral-differential form, equivalence between the two forms; 3 - reactor kinetics: fast neutrons and delayed neutrons, kinetic equations in punctual model, Nordheim equation, reactivity jumps, reactivity ramp; 4 - diffusion equation: local neutron status, Fick's law, diffusion equation, initial, boundary and interface conditions, nuclei in infinite and homogenous medium, some examples of solutions, developments in Eigenmodes; 5 - one-group theory: equation of the 'one-group - diffusion' theory, critical condition of the naked and homogenous reactor, critical condition of a reactor with reflectors, generalizations; 6 - neutrons moderation: different moderation mechanisms, elastic shock laws, moderation equation, some examples of solutions; 7 - resonance absorption of neutrons: advantage of the discontinuous moderation character, advantage of an heterogenous disposition, classical formula of the anti-trap factor in homogenous and heterogenous situation; 8 - neutrons thermalization: notions of thermalization mechanisms, thermalization equation, Maxwell spectrum, real spectrum, classical formula of the thermal utilisation factor, classical formula of the reproduction factor, moderation optimum. (J.S.)

  1. Relationships between PROMPT and gene expression

    DEFF Research Database (Denmark)

    Llinares, Marta Lloret; Mapendano, Christophe K; Martlev, Lasse H;

    2015-01-01

    Most mammalian protein-coding gene promoters are divergent, yielding promoter upstream transcripts (PROMPTs) in the reverse direction from their conventionally produced mRNAs. PROMPTs are rapidly degraded by the RNA exosome rendering a general function of these molecules elusive. Yet, levels...... of certain PROMPTs are altered in stress conditions, like the DNA damage response (DDR), suggesting a possible regulatory role for at least a subset of these molecules. Here we manipulate PROMPT levels by either exosome depletion or UV treatment and analyze possible effects on their neighboring genes...

  2. Search of a prompt gamma ray for chlorine analysis in a Portland cement sample

    International Nuclear Information System (INIS)

    Prompt Gamma Ray analysis of chlorine contaminated Portland cement samples have been carried out using an accelerator-based Prompt Gamma ray Neutron Activation Analysis setup. The chlorine concentration was measured over a range of 0.25-4 wt% using 1.165 MeV capture γ-rays from chlorine. The experimental results were compared with the results of Monte Carlo simulations and an excellent agreement was observed between the two results. Further theoretical study has shown that yield of the 1.165 MeV prompt γ-rays from chlorine is not very sensitive to variation in moisture contents of the Portland sample. An order of magnitude increase in sample moisture content resulted in only 16-20% increase in yield of 1.165 MeV prompt γ-rays

  3. Search of a prompt gamma ray for chlorine analysis in a Portland cement sample

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A. [Center for Applied Physical Sciences, King Fahd University of Petroleum and Minerals, Box 1815, Dhahran-31261 (Saudi Arabia)]. E-mail: annaqvi@kfupm.edu.sa; Nagadi, M.M. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia); Kidwai, S. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia); Khateeb-ur-Rehman [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia); Maslehuddin, M. [Center for Engineering Sciences, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia)

    2004-11-11

    Prompt Gamma Ray analysis of chlorine contaminated Portland cement samples have been carried out using an accelerator-based Prompt Gamma ray Neutron Activation Analysis setup. The chlorine concentration was measured over a range of 0.25-4 wt% using 1.165 MeV capture {gamma}-rays from chlorine. The experimental results were compared with the results of Monte Carlo simulations and an excellent agreement was observed between the two results. Further theoretical study has shown that yield of the 1.165 MeV prompt {gamma}-rays from chlorine is not very sensitive to variation in moisture contents of the Portland sample. An order of magnitude increase in sample moisture content resulted in only 16-20% increase in yield of 1.165 MeV prompt {gamma}-rays.

  4. Determination of neutron generation time in miniature neutron source reactor by measurement of neutronics transfer function

    Energy Technology Data Exchange (ETDEWEB)

    Hainoun, A.; Khamis, I. [Atomic Energy Commission, Damascus (Syria). Dept. of Physics

    2000-02-01

    The prompt neutron generation time {lambda} and the total effective fraction of delayed neutrons (including the effect of photoneutrons) {beta} have been experimentally determined for the miniature neutron source reactor (MNSR) of Syria. The neutron generation time was found by taking measurements of the reactor open-loop transfer function using newly devised reactivity-step-ejection method by the reactor pneumatic rabbit system. Small reactivity perturbations i.e. step changes of reactivity starting from steady state, were introduced into the reactor during operation at low power level i.e. zero-power. Relative neutron flux and reactivity versus time were obtained. Using transfer function analysis as well as least square fitting techniques and measuring the delayed neutrons fraction, the neutron generation time was determined to be 74.6{+-}1.57 {mu}s. Using the prompt jump approximation of neutron flux, the total effective fraction of delayed neutrons was measured and found to be 0.00783{+-}0.00017. Measured values of {lambda} and {beta} were found to be very consistent with calculated ones reported in the safety analysis report. (orig.)

  5. Determination of neutron generation time in miniature neutron source reactor by measurement of neutronics transfer function

    International Nuclear Information System (INIS)

    The prompt neutron generation time Λ and the total effective fraction of delayed neutrons (including the effect of photoneutrons) β have been experimentally determined for the miniature neutron source reactor (MNSR) of Syria. The neutron generation time was found by taking measurements of the reactor open-loop transfer function using newly devised reactivity-step-ejection method by the reactor pneumatic rabbit system. Small reactivity perturbations i.e. step changes of reactivity starting from steady state, were introduced into the reactor during operation at low power level i.e. zero-power. Relative neutron flux and reactivity versus time were obtained. Using transfer function analysis as well as least square fitting techniques and measuring the delayed neutrons fraction, the neutron generation time was determined to be 74.6±1.57 μs. Using the prompt jump approximation of neutron flux, the total effective fraction of delayed neutrons was measured and found to be 0.00783±0.00017. Measured values of Λ and β were found to be very consistent with calculated ones reported in the safety analysis report. (orig.)

  6. Contributions to the theory of fission neutron emission

    International Nuclear Information System (INIS)

    This report gives a compilation of recent work performed at Technical University, Dresden by D. Seeliger, H. Maerten and A. Ruben on the topic of fission neutron emission. In the first paper calculated fission neutron spectra are presented using the temperature distribution model FINESSE for fissioning actinide nuclei. In the second paper, starting from a general energy balance, Terrell's approach is generalized to describe average fragment energies as a function of incident energy; trends of fragment energy data in the Th-Pu region are well reproduced. In the third contribution, prompt fission neutron spectra and fragment characteristics for spontaneous fission of even Pu-isotopes are presented and discussed in comparison with experimental data using a phenomenological scission point model including temperature dependent shell effects. In the fourth paper, neutron multiplicities and energy spectra as well as average fragment energies for incident energies from threshold to 20 MeV (including multiple-chance fission) for U-238 are compared with traditional data representations. (author). Refs, figs and tabs

  7. 21 CFR 1401.7 - Prompt response.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Prompt response. 1401.7 Section 1401.7 Food and Drugs OFFICE OF NATIONAL DRUG CONTROL POLICY PUBLIC AVAILABILITY OF INFORMATION § 1401.7 Prompt response... determination, the reasons for the denial, and that an appeal may be lodged within the Office of National...

  8. Song Prompts: I Had a Cat

    Science.gov (United States)

    Kenney, Susan Hobson

    2011-01-01

    This article discusses song prompts as a way to encourage children to sing during exploratory play. A song prompt for "I Had a Cat" is included for educators to try in their own classrooms or preschools. Educators are invited to share ideas they have used that encourage children to sing during free play.

  9. 78 FR 5450 - Information Collection; Prompt Payment

    Science.gov (United States)

    2013-01-25

    ...; Prompt Payment AGENCY: Department of Defense (DOD), General Services Administration (GSA), and National... payment. DATES: Submit comments on or before March 26, 2013. ADDRESSES: Submit comments identified by Information Collection 9000- 0102, Prompt Payment, by any of the following methods: Regulations.gov :...

  10. 31 CFR 904.1 - Prompt referral.

    Science.gov (United States)

    2010-07-01

    ... COLLECTION STANDARDS (DEPARTMENT OF THE TREASURY-DEPARTMENT OF JUSTICE) REFERRALS TO THE DEPARTMENT OF JUSTICE § 904.1 Prompt referral. (a) Agencies shall promptly refer to the Department of Justice for... interest and penalties, shall be referred to the Civil Division or other division responsible...

  11. 38 CFR 1.950 - Prompt referral.

    Science.gov (United States)

    2010-07-01

    ... Referrals to Gao, Department of Justice, Or Irs § 1.950 Prompt referral. (a) VA shall promptly refer debts to Department of Justice (DOJ) for litigation where aggressive collection activity has been taken in... may direct, exclusive of interest and other late payment charges, shall be referred to the...

  12. Development and performance tests of NSTAR, a new type of compact neutron detector

    Science.gov (United States)

    Pawelczak, Iwona Agnieszka

    Development and performance of the NSTAR ("Neutron Sandwich Transmuter/Activation-gamma Radiator") are discussed, a neutron detector based on a new approach to Gd-loaded scintillators. This detector has high detection efficiency for neutrons, from thermal up to multi-MeV energies with practically zero energy threshold. The NSTAR operating principle is similar to that of Gd-loaded liquid scintillation detectors but avoids many of their disadvantages and hazards. The NSTAR scintillator has the dual function, both to thermalize fast neutrons and to generate responses to the dissipated neutron energy and the emission of associated delayed Gd neutron capture gamma-rays. Consequently, the NSTAR features a time dependent two-component response to neutrons, which consists of a prompt, energy dependent light flash followed by a delayed, energy independent signal. This characteristic response allows one to "tag" neutrons, distinguish them from gamma-rays, and to obtain neutron multiplicity information for multiple-neutron bursts. The detector modules consist of stacks of plastic scintillator slabs (Saint Gobain BC-408) alternating with thin Gd-loaded (0.5 wt.%) converter films (PDMS-SYLGARD 184). The stacks are viewed by fast photomultipliers (Philips XP2041) on one or both ends. The detector design combines high light output collection efficiency with large active volume. The NSTAR modules have been tested with neutrons produced by radioactive sources and a pulsed-beam neutron generator. Tests reveal an effective discrimination against gamma-rays, even in a high intensity background environment, when measurements are made relative to a reference signal. The NSTAR is capable of counting neutrons at rates of R ≤ 7 x 104 n/s with losses below 1% and can measure event by event two moments of the neutron multiplicity distribution. A detection efficiency of epsilon = (26 +/- 3)% was measured for DD-neutrons at an electronic threshold of Eth = 0.2 MeVee. The average neutron

  13. Measurement of the Syrian MNSR delayed neutron fraction and neutron generation time by noise analysis

    Energy Technology Data Exchange (ETDEWEB)

    Khamis, I. E-mail: ikhamis@aec.org.sy; Hainoun, A.; Suleiman, W

    2003-02-01

    Delayed neutron fraction {beta} and prompt neutron generation time {lambda} were determined for the Miniature Neutron Source Reactor of Syria using noise analysis technique. Small reactivity perturbations, step-wise and impulse in time, were introduced into the reactor at low power level i.e. zero-power. Power and reactivity versus time were obtained. Using the generalized least square algorithm and transfer function analysis, measurement of both the delayed neutron fraction and the neutron generation time were made. The MNSR values obtained for the prompt neutron generation time and delayed neutron fraction are 78.3{+-}1.3 {mu}s and 7.94{+-}0.11x10{sup -3} respectively. Both measured values of {beta} and {lambda} were found to be very consistent with previously measured and calculated ones reported in the Safety Analysis Report.

  14. Measurement of the Syrian MNSR delayed neutron fraction and neutron generation time by noise analysis

    International Nuclear Information System (INIS)

    Delayed neutron fraction β and prompt neutron generation time Λ were determined for the Miniature Neutron Source Reactor of Syria using noise analysis technique. Small reactivity perturbations, step-wise and impulse in time, were introduced into the reactor at low power level i.e. zero-power. Power and reactivity versus time were obtained. Using the generalized least square algorithm and transfer function analysis, measurement of both the delayed neutron fraction and the neutron generation time were made. The MNSR values obtained for the prompt neutron generation time and delayed neutron fraction are 78.3±1.3 μs and 7.94±0.11x10-3 respectively. Both measured values of β and Λ were found to be very consistent with previously measured and calculated ones reported in the Safety Analysis Report

  15. Measurement of the Syrian MNSR delayed neutron fraction and neutron generation time by noise analysis

    International Nuclear Information System (INIS)

    Delayed neutron fraction beta and prompt neutron generation time LAMBDA were determined for the Miniature Neutron Source Reactor of Syria using noise analysis technique. Small reactivity perturbations, step-wise and impulse in time, were introduced into the reactor at low power level i.e. zero-power. Power and reactivity versus time were obtained. Using the generalized least square algorithm and transfer function analysis, measurement of both the delayed neutron fraction and the neutron generation time were made. The MNSR values obtained for the prompt neutron generation time and delayed neutron fraction are 78.3+-1.3 mu s and 7.94+-0.11x10 sup - sup 3 respectively. Both measured values of beta and LAMBDA were found to be very consistent with previously measured and calculated once reported in the Safety Analysis Report. (author)

  16. Evaluation of proton inelastic reaction models in Geant4 for prompt gamma production during proton radiotherapy

    Science.gov (United States)

    Jeyasugiththan, Jeyasingam; Peterson, Stephen W.

    2015-10-01

    During proton beam radiotherapy, discrete secondary prompt gamma rays are induced by inelastic nuclear reactions between protons and nuclei in the human body. In recent years, the Geant4 Monte Carlo toolkit has played an important role in the development of a device for real time dose range verification purposes using prompt gamma radiation. Unfortunately the default physics models in Geant4 do not reliably replicate the measured prompt gamma emission. Determining a suitable physics model for low energy proton inelastic interactions will boost the accuracy of prompt gamma simulations. Among the built-in physics models, we found that the precompound model with a modified initial exciton state of 2 (1 particle, 1 hole) produced more accurate discrete gamma lines from the most important elements found within the body such as 16O, 12C and 14N when comparing them with the available gamma production cross section data. Using the modified physics model, we investigated the prompt gamma spectra produced in a water phantom by a 200 MeV pencil beam of protons. The spectra were attained using a LaBr3 detector with a time-of-flight (TOF) window and BGO active shield to reduce the secondary neutron and gamma background. The simulations show that a 2 ns TOF window could reduce 99% of the secondary neutron flux hitting the detector. The results show that using both timing and active shielding can remove up to 85% of the background radiation which includes a 33% reduction by BGO subtraction.

  17. Coincident measurements of prompt fission γ rays and fission fragments at DANCE

    Science.gov (United States)

    Walker, C. L.; Baramsai, B.; Jandel, M.; Rusev, G.; Couture, A.; Mosby, S.; Ullmann, J.; Kawano, T.; Stetcu, I.; Talou, P.

    2015-10-01

    Modern statistical approaches to modeling fission involve the calculation of not only average quantities but also fully correlated distributions of all fission products. Applications such as those involving the detection of special nuclear materials also rely on fully correlated data of fission products. Experimental measurements of correlated data are thus critical to the validation of theory and the development of important applications. The goal of this experiment was to measure properties of prompt fission gamma-ray emission as a function of fission fragments' total kinetic energy in the spontaneous fission of 252Cf. The measurement was carried out at the Detector for Advanced Neutron Capture Experiments (DANCE), a 4 π γ-ray calorimeter. A prototype design consisting of two silicon detectors was installed in the center of DANCE, allowing simultaneous measurement of fission fragments and γ rays. Effort has been taken to simulate fragment kinetic energy losses as well as γ-ray attenuation in DANCE using such tools as GEANT4 and SRIM. Theoretical predictions generated by the code CGMF were also incorporated as input for these simulations. Results from the experiment and simulations will be presented, along with plans for future measurements.

  18. Study on Prompt NOx Emission in Boilers

    Institute of Scientific and Technical Information of China (English)

    ZhongB.J.; RoslyakovP.V.

    1996-01-01

    Experimental and theoretical investigation of prompt nitrogen oxides emission in flame of different gaseous fuels were carried out with purpose of minimizing total NOx yield.The effect of the following factors was determined:air excess from 0.3 to 1.1,flame temperature,heating flame rate,fuel content,It was found that ,if air excess was less than 0.65,some prompt NOx converted to N2 in consequence of reacting with hydrocarbon radicals.

  19. Prompt neutrino flux in the atmosphere revisited

    CERN Document Server

    Garzelli, M V; Sigl, G

    2016-01-01

    Prompt neutrino fluxes due to the interactions of high-energy cosmic rays with the Earth's atmosphere are backgrounds in the search for high-energy neutrinos of galactic or extra-galactic origin performed by Very Large Volume Neutrino Telescopes. We summarize our predictions for prompt neutrinos, showing their basic features as emerging from the calculation in a QCD framework capable of describing recent charm data from the Large Hadron Collider.

  20. Indian experience in neutron beam utilization: Inhouse and collaborative programs

    International Nuclear Information System (INIS)

    Neutron beam research, initiated in India during the late fifties, has evolved into the present National Facility for Neutron Beam Research (NFNBR), operated at Bhabha Atomic Research Centre (BARC), Mumbai, by scientists of Solid State Physics Division (SSPD). Dhruva, a 100 MW, natural uranium fuelled, heavy water moderated, and heavy water cooled research reactor, is the main source of neutrons, with a flux of about 1.8x1014 neutrons/cm2/s, for NFNBR. A four-circle single-crystal diffractometer, two powder diffractometers, a high-Q diffractometer, a polarization analysis spectrometer, a triple-axis spectrometer, a filter detector spectrometer, and a quasi-elastic scattering spectrometer are located inside Dhruva reactor hall, while two small-angle neutron scattering instruments are operational in the adjacent Guide-Tube Laboratory (GTL). A polarized neutron reflectometer has recently become operational, and a spin-echo spectrometer is under installation. Two neutron guide tubes, G1 and G2 (length: 21m and 35m, radius of curvature: 1916m and 3452m, characteristic wavelength: 3.0A and 2.2A respectively) transport neutron beams to GTL from the reactor hall. Average flux at the breaks, provided on the guides to accommodate various instruments, is about 107 neutrons/cm2/s. A neutron interferometer, originally installed at CIRUS reactor, is being upgraded, and plans to build a prompt gamma-ray neutron activation analysis facility, in collaboration with Radio Chemistry Division (RCD), are currently underway. Apsara reactor houses the neutron radiography and detector development facilities. Neutron detectors are developed and fabricated by NFNBR, for both in-house use, and supply to other users in the country. Linear position-sensitive detectors, using helium-3, have been developed and extensively used at BARC during the past decade. A two dimensional position-sensitive detector has also been fabricated and tested recently. All the neutron instruments, guide tubes

  1. Subnanosecond current mode detectors for prompt physical process diagnosis

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    For prompt physical diagnosis, several types of subnanosecond current mode detectors have been developed,including scintillator detectors with large linear output current,GaAs:Cr and InP:Fe photoconductor detectors(PCD), and X-ray diodes(XRD), etc. The characteristic of scintillation light of BaF2 crystal doped with La and of plastic scintillator ST1422 with slow component quencher are described. As for the photoconductor detectors, the main performance of neutron damaged GaAs:Cr and InP:Fe were studied. In addition, the spectral response of an XRD with coaxial leading-out end was also studied. These detectors have been successfully applied to nuclear test diagnosis and ICF research.

  2. Optomechanical design of a prompt gamma reaction history diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Hermann, Hans W [Los Alamos National Laboratory; Kaufman, Morris I [Los Alamos National Laboratory; Malone, Robert M [NSTEC; Frogget, Brent C [NSTEC; Tunnell, Thomas W [NSTEC; Cox, Brian [NSTEC; Frayer, Daniel K [NSTEC; Ali, Zaheer [NSTEC; Stoeffl, Wolfgang [LLNL

    2009-01-01

    The National Ignition Facility and the Omega Laser Facility both have a need for measuring prompt gamma radiation as part of a nuclear diagnostic program. A new gamma-detection diagnostic using off-axis-parabolic mirrors has been built. Some new techniques were used in the design, construction, and tolerancing of this gamma ray diagnostic. Because of the wavelength requirement (250-700 nm), the optical element surface finishes were a key design consideration. The optical enclosure had to satisfy pressure safety concerns and shielding against electromagnetic interference induced by gammas and neutrons. Structural finite element analysis was needed to meet rigorous optical and safety requirements. The optomechanical design is presented. Alignment issues are also discussed.

  3. Investigating the Effects of Prompt Characteristics on the Comparability of TOEFL iBT™ Integrated Writing Tasks

    Science.gov (United States)

    Cho, Yeonsuk; Rijmen, Frank; Novák, Jakub

    2013-01-01

    This study examined the influence of prompt characteristics on the averages of all scores given to test taker responses on the TOEFL iBT[TM] integrated Read-Listen-Write (RLW) writing tasks for multiple administrations from 2005 to 2009. In the context of TOEFL iBT RLW tasks, the prompt consists of a reading passage and a lecture. To understand…

  4. Mining Archived HYSPEC User Data to Analyze the Prompt Pulse at the SNS

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Michael B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Iverson, Erik B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gallmeier, Franz X. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Winn, Barry L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-10-01

    The Hybrid-Spectrometer (HYSPEC) is one of 17 instruments currently operated at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratories (ORNL). The secondary spectrometer of this instrument is located inside an out-building off the north side of the SNS instrument hall. HYSPEC has experienced a larger background feature than similar inelastic instruments since its commissioning in 2011. This background feature is caused by a phenomenon known as the “prompt pulse” which is an essential part of neutron production in a pulsed spallation source but comes with unfortunate side effects.

  5. Precise determination of silicon in ceramic reference materials by prompt gamma activation analysis at JRR-3

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Tsutomu [National Metrology Institute of Japan-AIST, Ibaraki (Japan); Matsue, Hideaki [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Ibaraki (Japan)

    2016-04-15

    Prompt gamma activation analysis using a thermal neutron-guided beam at Japan Atomic Energy Agency JRR-3M was applied for the precise determination of Si in silicon nitride ceramic reference materials [Japan Ceramic Reference Material (JCRM) R 003]. In this study, the standard addition method coupled with internal standard was used for the nondestructive determination of Si in the sample. Cadmium was used as internal standard to obtain the linear calibration curves and to compensate for the neutron beam variability. The analytical result of determining Si in JCRM R 003 silicon nitride fine powder ceramic reference materials using prompt gamma activation analysis was in good agreement with that obtained by classical gravimetric analysis. The relative expanded measurement uncertainty (k = 2) associated with the determined value was 2.4%.

  6. The transfer function for a subcritical system measured by prompt gamma radiation

    International Nuclear Information System (INIS)

    The source transfer function has been measured in a natural uranium-light water moderated sub-critical assembly as a function of source frequency and position. Using a square wave input of fast neutrons from the D-T reaction prompt gamma radiation from fission was detected and the time variation of the detector output recorded on a multichannel analyser. By Fourier analysing the recorded waveform the source transfer function was found. Two group diffusion theory was used to determine the spatially dependent source transfer function for a system similar to the experimental one. The computer programs ATEST and GAMMARESFU, were written to calculate the neutron flux in the core and also prompt fission gamma rays response function outside the subcritical assembly at chosen frequency and detector position. The method gave good agreement with the experiment. (U.K.)

  7. Calculation of prompt doses induced by fusion experiments in Laser MegaJoule facility

    Energy Technology Data Exchange (ETDEWEB)

    Baggio, Jacques, E-mail: jacques.baggio@projet-lmj.org [CEA/CESTA BP2 33114 Le Barp (France); Jacquet, Henri-Patrick [CEA/DIF, Bruyeres Le Chatel 91297 Arpajon Cedex (France); Schneider, Philippe; Javier, Francois [CEA/CESTA BP2 33114 Le Barp (France)

    2011-10-15

    The Laser MegaJoule (LMJ), built at CEA/CESTA near Bordeaux, France, will conduct research in the field of plasma physics and inertial confinement fusion. Some of these experiments are designed to produce during less than one nanosecond up to 10{sup 19} neutrons at 14 MeV in indirect drive mode. The 300 m long building that hosts both laser sources and target chamber was designed to confine neutron and gamma fluxes in the experiment hall during a shot. Monte Carlo simulations were performed using a TRIPOLI 4 modelling of the facility to ensure that prompt doses in occupied areas inside the facility that host employees during a shot will be sufficiently low. Although significant radiation levels inside the experiment hall, prompt doses in occupied rooms are limited to a few {mu}Sv per shot which is fully compatible with radiation level limits.

  8. Averaging anisotropic cosmologies

    International Nuclear Information System (INIS)

    We examine the effects of spatial inhomogeneities on irrotational anisotropic cosmologies by looking at the average properties of anisotropic pressure-free models. Adopting the Buchert scheme, we recast the averaged scalar equations in Bianchi-type form and close the standard system by introducing a propagation formula for the average shear magnitude. We then investigate the evolution of anisotropic average vacuum models and those filled with pressureless matter. In the latter case we show that the backreaction effects can modify the familiar Kasner-like singularity and potentially remove Mixmaster-type oscillations. The presence of nonzero average shear in our equations also allows us to examine the constraints that a phase of backreaction-driven accelerated expansion might put on the anisotropy of the averaged domain. We close by assessing the status of these and other attempts to define and calculate 'average' spacetime behaviour in general relativity

  9. Prompt Gamma-ray 3D-Imaging for Cultural Heritage Purposes

    OpenAIRE

    Schulze, Ralf

    2010-01-01

    The development of new, and the enhancement of existing element-sensitive imaging methods utilizing neutrons of different energy regions was the aim of the European ANCIENT CHARM project. During the present work the setup for Prompt Gamma-ray Activation Analysis (PGAA) at the research reactor FRM 2 in Garching near Munich was modified to enable the spatial mapping of elemental abundances in the analysed samples. Because the PGAA setup at FRM 2 was under construction at the beginning of the pr...

  10. Fission prompt γ-ray multiplicity distribution measurements and simulations at DANCE

    International Nuclear Information System (INIS)

    The nearly energy independence of the DANCE efficiency and multiplicity response to γ rays makes it possible to measure the prompt γ-ray multiplicity distribution in fission. We demonstrate this unique capability of DANCE through the comparison of γ-ray energy and multiplicity distribution between the measurement and numerical simulation for three radioactive sources 22Na, 60Co, and 88Y. The prospect for measuring the γ-ray multiplicity distribution for both spontaneous and neutron-induced fission is discussed.

  11. Analysis of prompt decay experiments for ADS reactivity monitoring at VENUS-F facility

    International Nuclear Information System (INIS)

    The strategy chosen to monitor a subcritical core reactivity combines two approaches: 1) the on-line monitoring of the relative fluctuations of the reactivity ρ(t), due to the measurement of the ratio of the beam intensity to the reactor power; 2) some calibration measurements, performed regularly, providing an absolute level of ρ. These absolute or calibration measurements are performed during beam interruptions and are based on the analysis of the time decay of the reactor neutron population, N(t). Different analysis techniques can be applied, but most of them require analysing both prompt and delayed neutron contributions (as the area method). Consequently, to give precise results, these techniques require the use of long beam interruptions of several ms durations. This paper focuses on the prompt decay part of N(t) and presents a method to determine the prompt multiplication factor kp, from which the keff can be inferred. This method requires shorter beam interruptions of a few tens of microseconds. The method is applied to Pulsed Neutron Source (PNS) measurements at the VENUS-F facility. The VENUS-F Facility is a zero power ADS mock-up and consists in the vertical coupling of the VENUS reactor (at SCK-CEN, Mol, Belgium) with a deuteron accelerator GENEPI-3C

  12. Thermal-neutron capture for A=36-44

    CERN Document Server

    Chunmei, Z

    2003-01-01

    A new evaluation has been undertaken of the level properties, prompt gamma rays and decay scheme properties of thermal neutron capture for nuclides with mass number A=36-44. The cutoff date is March 2002. This evaluation is effectively an update of the data table of the Prompt Gamma Rays from Thermal Neutron Capture as published in Atomic Data and Nuclear Data Tables 26, 511, (1981).

  13. Interferences in Prompt γ Analysis of corrosive contaminants in concrete

    Science.gov (United States)

    Naqvi, A. A.; Nagadi, M. M.; Al-Amoudi, O. S. B.

    2006-12-01

    An accelerator-based Prompt Gamma Neutron Activation Analysis (PGNAA) setup has been developed to measure the concentration of corrosive chloride and sulfate contaminants in concrete. The Minimum Detectable Concentration (MDC) limit of chlorine and sulfur in the concrete depends upon the γ-ray used for elemental analysis. For more interfering γ-rays, the MDC limit is higher than that for less interfering γ-rays. The MDC limit of sulfur in concrete measured for the KFUPM PGNAA setup was calculated to be 0.60±0.19 wt%. The MDC limit is equal to the upper limit of sulfur concentration in concrete set by the British Standards. The MDC limit of chlorine in concrete for the KFUPM PGNAA setup, which was calculated for less interfering 1.165 MeV γ-rays, was found to be 0.075±0.025 wt%. The lower limits of the MDC of chlorine in concrete was 73% higher than the limit set by American Concrete Institute. The limit of the MDC can be improved to the desired standard by increasing the intensity of neutron source. For moreinterfering 5.715 and 6.110 MeV chlorine γ-rays the MDC limit was found to be 2-3 times larger than that of 1.165 MeV γ-rays. When normalized to the same intensity of the neutron source, the MDC limits of chlorine and sulfur in concrete from the KFUPM PGNAA setup are better than MDC limits of chlorine in concrete obtained with the 241Am-Be source-based PGNAA setup. This study has shown that an accelerator-based PGNAA setup can be used in chlorine and sulfur analysis of concrete samples.

  14. Measurements of neutron capture cross sections

    International Nuclear Information System (INIS)

    A review of measurement techniques for the neutron capture cross sections is presented. Sell transmission method, activation method, and prompt gamma-ray detection method are described using examples of capture cross section measurements. The capture cross section of 238U measured by three different prompt gamma-ray detection methods (large liquid scintillator, Moxon-Rae detector, and pulse height weighting method) are compared and their discrepancies are resolved. A method how to derive the covariance is described. (author)

  15. Recent activities on neutron beam utilization

    International Nuclear Information System (INIS)

    In Japan, the utilization of neutron beam brought out in research reactors had mainly been carried out in KUR of Kyoto University and JRR-2 of Japan Atomic Energy Research Institute (JAERI) in the fields of neutron scattering experiment, neutron radiography, neutron induced prompt-gamma ray analysis, medical and biological irradiation and so on. After the completion of upgrading work of JRR-3 in JAERI in 1990 (JRR-3M), the quality and quantity for the neutron beam experiments are extremely improved by means of its high intensity of neutron flux and high signal-to-noise ratio of cold and thermal neutron beams at more than twenty neutron beam ports. Especially, the cold neutron beam has brought the field of the utilization expanded and the neutron guide tubes have increased the number of neutron beam facilities as if there are three research reactors. These facilities induced to more active use of research reactors and increased the researchers in the many fields. At present, research reactors are utilized widely in various fields of not only nuclear researches but also non-nuclear researches and industrial uses. The JRR-3M has been operated only for about three years, however, interesting results have already been obtained using cold and thermal neutron beams. The current status of the neutron beam utilization using the research reactors in JAERI is reported and also several research topics obtained at JRR-3M are introduced in this presentation. (author)

  16. Further Study of Prompt Neutrino Production in a Proton Beam Dump Experiment

    CERN Multimedia

    2002-01-01

    In previous beam dump experiments at CERN, the production of prompt @n^e and @n(@m) in proton-nucleus collisions has been established. A difference in the prompt @n^e and @n(@m) fluxes which would indicate new physics, cannot be ruled out on the basis of existing data.\\\\ \\\\ The main aim of this beam dump experiment is to check with much better accuracy the equality of the prompt @n^e and @n(@m) fluxes. The use of two copper dumps with average density 1 and 1/3 permits the separation of the prompt and conventional neutrino fluxes by extrapolation to infinite density. The dumps will be located at the downstream end of the decay tunnel of the SPS neutrino facility.

  17. Comparison of multiple prompt γ-ray analysis and prompt γ-ray analysis for the elemental analysis of geological and cosmochemical samples.

    Science.gov (United States)

    Islam, Mohammad Amirul; Ebihara, Mitsuru; Toh, Yosuke; Harada, Hideo

    2011-10-01

    Multiple prompt γ-ray analysis (MPGA) and conventional neutron-induced prompt γ-ray analysis (PGA) are nondestructive analytical methods for bulk chemical compositions, and their analytical capabilities were compared for elemental analyses of geological and cosmochemical samples. Detection sensitivities of PGA are often restricted by poor signal-to-noise ratios and interferences from different origins. MPGA can substantially reduce the background level, especially for hydrogenous samples, relative to PGA, which opens up a possibility to use lower energy prompt γ-rays of some trace elements. Although it is one of the major constituent elements of rock samples, Mg is hard to be determined by PGA. With MPGA, Mg contents could be determined with reasonable consistency with their corresponding recommended values in geological and cosmochemical samples by carefully selecting suitable coincident prompt γ-ray energy pairs without interference correction. MPGA was applied to a hydrogenous meteorite, Ivuna, which contains H at 2% mass level. MPGA detection limits for most of the elements studied can be reduced up to 1 order of magnitude when compared with PGA detection limits under the present experimental conditions. PMID:21823645

  18. Prompt gamma-ray activation analysis (PGAA)

    Energy Technology Data Exchange (ETDEWEB)

    Kern, J. [Fribourg Univ. (Switzerland). Inst. de Physique

    1996-11-01

    The paper deals with a brief description of the principles of prompt gamma-ray activation analysis (PGAA), with the detection of gamma-rays, the PGAA project at SINQ and with the expected performances. 8 figs., 3 tabs., 10 refs.

  19. 45 CFR 1701.5 - Prompt response.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Prompt response. 1701.5 Section 1701.5 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL COMMISSION ON LIBRARIES AND... Saturdays, Sundays and legal public holidays) of the receipt of a request, the Associate Director...

  20. Drought prompts government to close nuclear plant

    CERN Multimedia

    2003-01-01

    "A nuclear power plant was shut down Sunday because a record drought left insufficient water to cool down the reactor. The plant supplies more than 10 percent of Romania's electricity and closure prompted fears of a price hike" (1/2 page).

  1. Engaging Young Students in Scientific Investigations: Prompting for Meaningful Reflection

    Science.gov (United States)

    Wilson, Travis; Perry, Michelle; Anderson, Carolyn J.; Grosshandler, Dean

    2012-01-01

    This study examined the verbal prompts a tutor used to promote reflection and young students' responses to these prompts. Seven children (ages 8-12) participated in 260 min of one-on-one tutoring to learn scientific concepts related to gear movement; the tutor spontaneously provided these students with 763 prompts for reflection. Prompts reliably…

  2. Development and Test of a Neutron Imaging Setup at the PGAA Instrument at FRM II

    OpenAIRE

    Söllradl, S.; Mühlbauer, M. J.; Kudejova, P.; Türler, Andreas

    2015-01-01

    We report on the developments of a neutron tomography setup at the instrument for prompt gamma-ray activation analysis (PGAA) at the Maier-Leibnitz Zentrum(MLZ). The recent developments are driven by the idea of combining the spatial information obtained with neutron tomography with the elemental information determined with PGAA, i.e. to further combine both techniques to an investigative technique called prompt gamma activation imaging (PGAI).At the PGAA instrument, a cold neutron flux of up...

  3. Average-energy games

    OpenAIRE

    Bouyer, Patricia; Markey, Nicolas; Randour, Mickael; Larsen, Kim G.; Laursen, Simon

    2015-01-01

    Two-player quantitative zero-sum games provide a natural framework to synthesize controllers with performance guarantees for reactive systems within an uncontrollable environment. Classical settings include mean-payoff games, where the objective is to optimize the long-run average gain per action, and energy games, where the system has to avoid running out of energy. We study average-energy games, where the goal is to optimize the long-run average of the accumulated energy. We show that this ...

  4. A Monte Carlo Simulation of Prompt Gamma Emission from Fission Fragments

    Directory of Open Access Journals (Sweden)

    Litaize O.

    2013-03-01

    Full Text Available The prompt fission gamma spectra and multiplicities are investigated through the Monte Carlo code FIFRELIN which is developed at the Cadarache CEA research center. Knowing the fully accelerated fragment properties, their de-excitation is simulated through a cascade of neutron, gamma and/or electron emissions. This paper presents the recent developments in the FIFRELIN code and the results obtained on the spontaneous fission of 252Cf. Concerning the decay cascades simulation, a fully Hauser-Feshbach model is compared with a previous one using a Weisskopf spectrum for neutron emission. A particular attention is paid to the treatment of the neutron/gamma competition. Calculations lead using different level density and gamma strength function models show significant discrepancies of the slope of the gamma spectra at high energy. The underestimation of the prompt gamma spectra obtained regardless our de-excitation cascade modeling choice is discussed. This discrepancy is probably linked to an underestimation of the post-neutron fragments spin in our calculation.

  5. From EXILL (EXogam at the ILL to FIPPS (FIssion Product Prompt γ-ray Spectrometer

    Directory of Open Access Journals (Sweden)

    Blanc A.

    2015-01-01

    Full Text Available Within the EXILL campaign a large and efficient cluster of Ge-detectors was installed around a very well collimated neutron beam. This has allowed to carry out rather complete spectroscopic studies close to the line of stability using the (n,γ reaction. Neutron rich isotopes were produced by neutron induced fission and prompt spectroscopy was carried out. The isotope selection in this setup was based on a partially known level scheme and the use of triple coincidences. The latter is limiting the statistical sensitivity in the case of weak production yields. Based on the experiences of these campaigns we are currently developing a new setup: FIPPS (FIssion Product Prompt Spectroscopy. This setup combines a collimated neutron beam, a highly efficient cluster of Ge detectors, a gas filled magnet and auxiliary detectors. The presence of the gas filled magnet will allow us to identify fission products directly and should give access to a new quality of studies if compared to the EXILL campaign. The EXILL campaign and the FIPPS project are presented.

  6. Pulsed neutron generator for logging

    International Nuclear Information System (INIS)

    A pulsed neutron generator for uranium logging is described. This generator is one component of a prototype uranium logging probe which is being developed by SLA to detect, and assay, uranium by borehole logging. The logging method is based on the measurement of epithermal neutrons resulting from the prompt fissioning of uranium from a pulsed source of 17.6 MeV neutrons. An objective of the prototype probe was that its diameter not exceed 2.75 inches, which would allow its use in conventional rotary drill holes of 4.75-inch diameter. This restriction limited the generator to a maximum 2.375-inch diameter. The performance requirements for the neutron generator specified that it operate with a nominal output of 5 x 106 neutrons/pulse at up to 100 pulses/second for a one-hour period. The development of a neutron generator meeting the preliminary design goals was completed and two prototype models were delivered to SLA. These two generators have been used by SLA to log a number of boreholes in field evaluation of the probe. The results of the field evaluations have led to the recommendation of several changes to improve the probe's operation. Some of these changes will require additional development effort on the neutron generator. It is expected that this work will be performed during 1977. The design and operation of the first prototype neutron generators is described

  7. Averaged extreme regression quantile

    OpenAIRE

    Jureckova, Jana

    2015-01-01

    Various events in the nature, economics and in other areas force us to combine the study of extremes with regression and other methods. A useful tool for reducing the role of nuisance regression, while we are interested in the shape or tails of the basic distribution, is provided by the averaged regression quantile and namely by the average extreme regression quantile. Both are weighted means of regression quantile components, with weights depending on the regressors. Our primary interest is ...

  8. On the Averaging Principle

    OpenAIRE

    Fibich, Gadi; Gavious, Arieh; Solan, Eilon

    2012-01-01

    Typically, models with a heterogeneous property are considerably harder to analyze than the corresponding homogeneous models, in which the heterogeneous property is replaced with its average value. In this study we show that any outcome of a heterogeneous model that satisfies the two properties of differentiability and interchangibility is O(\\epsilon^2) equivalent to the outcome of the corresponding homogeneous model, where \\epsilon is the level of heterogeneity. We then use this averaging pr...

  9. Average Angular Velocity

    OpenAIRE

    Van Essen, H.

    2004-01-01

    This paper addresses the problem of the separation of rotational and internal motion. It introduces the concept of average angular velocity as the moment of inertia weighted average of particle angular velocities. It extends and elucidates the concept of Jellinek and Li (1989) of separation of the energy of overall rotation in an arbitrary (non-linear) $N$-particle system. It generalizes the so called Koenig's theorem on the two parts of the kinetic energy (center of mass plus internal) to th...

  10. On Averaging Rotations

    DEFF Research Database (Denmark)

    Gramkow, Claus

    1999-01-01

    In this article two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very offten the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong...... approximations to the Riemannian metric, and that the subsequent corrections are inherient in the least squares estimation. Keywords: averaging rotations, Riemannian metric, matrix, quaternion...

  11. The new prompt gamma-ray activation facility at the Paul Scherrer Institute, Switzerland

    CERN Document Server

    Crittin, M; Schenker, J L

    2000-01-01

    Since October 1997, a new Prompt Gamma-ray Activation (PGA) facility at the neutron spallation source SINQ of the Paul Scherrer Institute (PSI) in Villigen, Switzerland, is operational. The detection system includes a Compton-suppression spectrometer and a pair spectrometer. An interesting feature of this PGA facility is the capillary-based neutron focusing optics which permits scanning of samples and nuclear spectroscopy of isotopes having small capture cross sections. During the beam periods 1997 and 1998, measurements were undertaken to characterize the PGA facility (gamma-ray background, efficiencies of the two spectrometers, analytical sensitivities and detection limits for several elements, performances of the neutron lens). Elemental analyses of standards were also performed.

  12. Analysis Framework for the Prompt Discovery of Compact Binary Mergers in Gravitational-wave Data

    CERN Document Server

    Messick, Cody; Brady, Patrick; Brockill, Patrick; Cannon, Kipp; Caudill, Sarah; Chamberlin, Sydney J; Creighton, Jolien D E; Everett, Ryan; Hanna, Chad; Lang, Ryan N; Li, Tjonnie G F; Meacher, Duncan; Pankow, Chris; Privitera, Stephen; Qi, Hong; Sachdev, Surabhi; Sadeghian, Laleh; Sathyaprakash, B; Singer, Leo; Thomas, E Gareth; Wade, Leslie; Wade, Madeline; Weinstein, Alan

    2016-01-01

    We describe a stream-based analysis pipeline to detect gravitational waves from the merger of binary neutron stars, binary black holes, and neutron-star-black-hole binaries within ~ 1 minute of the arrival of the merger signal at Earth. Such low-latency detection is crucial for the prompt response by electromagnetic facilities in order to observe any fading electromagnetic counterparts that might be produced by mergers involving at least one neutron star. Even for systems expected not to produce counterparts, analysis of the data in low-latency for their GW signals is useful for deciding when not to point telescopes, and as feedback to observatory operations. The pipeline also operates in an offline mode, in which it incorporates more refined information about data quality and employs acausal methods that are inapplicable to the online mode.

  13. Comparison of Simultaneous Prompting and No-No Prompting in Two-Choice Discrimination Learning with Children with Autism

    Science.gov (United States)

    Leaf, Justin B.; Sheldon, Jan B.; Sherman, James A.

    2010-01-01

    This study compared no-no prompting procedures to simultaneous prompting procedures for 3 children with autism. Using a parallel treatments design, researchers taught rote math skills, receptive labels, or answers to "wh-" questions with both prompting systems. Results indicated that no-no prompting was effective in teaching all skills. By…

  14. Time correlated measurements using plastic scintillators with neutron-photon pulse shape discrimination

    Science.gov (United States)

    Richardson, Norman E., IV

    Since the beginning of the nuclear age, there has been a strong demand for the development of efficient technologies for the detection of ionizing radiation. According to the United States' Department of Energy, the accurate assessment of fissile materials is essential in achieving the nonproliferation goals of enhancing safety and security of nuclear fuel cycle and nuclear energy facilities. Nuclear materials can be characterized by the measurement of prompt and delayed neutrons and gamma rays emitted in spontaneous or induced fission reactions and neutrons emitted in fission reactions are the distinctive signatures of nuclear materials. Today, the most widely used neutron detection technologies rely on thermal neutron capture reactions using a moderating material to cause the neutron to lose its energy prior to the detection event. This is necessary because as the fission event occurs, neutrons are emitted carrying high amounts of energy, typically on the order of mega electron volts (MeV). These energetic particles are classified as "fast" neutrons. For detecting the thermal neutrons, the Helium-3 (3He) gas-filled counters are arguably the most widely used technology of neutron detection. 3He counters have been the scientific standard for the nuclear engineering community for several decades, and have earned their place as a reliable technique for the detection of neutrons. However, 3He gas-filled counters have several disadvantages. First, gas-filled counters are not rigid and are sensitive to vibrations. Secondly, gas-filled counters are prone to the count rate limitations due to the physical processes of charge multiplication and transport in the gas medium in the electric field. Lastly, 3He gas-filled counters suffer from a supply shortage of the 3He isotope. As it is stated in [3], this shortage is created by the new demand for Helium-3 due to the deployment of neutron detectors at the borders after the 9/11 attack to help secure the nation against smuggled

  15. Self-shielding coefficient and thermal flux depression factor of voluminous sample in neutron activation analysis

    International Nuclear Information System (INIS)

    Full text: One of the major problems encountered during the irradiation of large inhomogeneous samples in performing activation analysis using neutron is the perturbation of the neutron field due to absorption and scattering of neutron within the sample as well as along the neutron guide in the case of prompt gamma activation analysis. The magnitude of this perturbation shown by self-shielding coefficient and flux depression depend on several factors including the average neutron energy, the size and shape of the sample, as well as the macroscopic absorption cross section of the sample. In this study, we use Monte Carlo N-Particle codes to simulate the variation of neutron self-shielding coefficient and thermal flux depression factor as a function of the macroscopic thermal absorption cross section. The simulation works was carried out using the high performance computing facility available at UTM while the experimental work was performed at the tangential beam port of Reactor TRIGA PUSPATI, Malaysia Nuclear Agency. The neutron flux measured along the beam port is found to be in good agreement with the simulated data. Our simulation results also reveal that total flux perturbation factor decreases as the value of absorption increases. This factor is close to unity for low absorbing sample and tends towards zero for strong absorber. In addition, sample with long mean chord length produces smaller flux perturbation than the shorter mean chord length. When comparing both the graphs of self-shielding factor and total disturbance, we can conclude that the total disturbance of the thermal neutron flux on the large samples is dominated by the self-shielding effect. (Author)

  16. Synovectomy by Neutron capture

    International Nuclear Information System (INIS)

    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 Pu239 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)

  17. Scission neutrons for U, Pu, Cm, and Cf isotopes: Relative multiplicities calculated in the sudden limit

    Science.gov (United States)

    Capote, R.; Carjan, N.; Chiba, S.

    2016-02-01

    The multiplicities of scission neutrons νs c are calculated for series of U, Pu, Cm, and Cf isotopes assuming a sudden transition between two different nuclear configurations (αi→αf ): one just before the neck rupture and one immediately after the disappearance of the neck. This calculation requires only the knowledge of the corresponding two sets of neutron eigenstates. The nuclear shapes around the scission point are described in terms of Cassinian ovals with only two parameters: α (that positions the shape with respect to the zero-neck shape) and α1 (that defines the mass asymmetry). Based on these shapes, a neutron mean field of the Woods-Saxon type is constructed using two prescriptions to calculate the distance to the nuclear surface. The accent in the present work is put on the dependence of νs c on the neutron number Nf of the fissioning nucleus and on the mass asymmetry AL/AH of the primary fission fragments. The relative dependence of these multiplicities, averaged over the mass yields, , are finally compared with existing experimental data on prompt fission neutrons .

  18. THE ELECTROMAGNETIC MODEL OF SHORT GRBs, THE NATURE OF PROMPT TAILS, SUPERNOVA-LESS LONG GRBs, AND HIGHLY EFFICIENT EPISODIC ACCRETION

    Energy Technology Data Exchange (ETDEWEB)

    Lyutikov, Maxim [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907-2036 (United States)

    2013-05-01

    Many short gamma-ray bursts (GRBs) show prompt tails lasting up to hundreds of seconds that can be energetically dominant over the initial sub-second spike. In this paper we develop an electromagnetic model of short GRBs that explains the two stages of the energy release, the prompt spike and the prompt tail. The key ingredient of the model is the recent discovery that an isolated black hole can keep its open magnetic flux for times much longer than the collapse time and thus can spin down electromagnetically, driving the relativistic wind. First, the merger is preceded by an electromagnetic precursor wind with total power L{sub p} Almost-Equal-To (((GM{sub NS}){sup 3}B{sub NS}{sup 2})/c{sup 5}R){proportional_to}(-t){sup - Vulgar-Fraction-One-Quarter }, reaching 3 Multiplication-Sign 10{sup 44} erg s{sup -1} for typical neutron star masses of 1.4 M{sub Sun} and magnetic fields B {approx} 10{sup 12} G. If a fraction of this power is converted into pulsar-like coherent radio emission, this may produce an observable radio burst of a few milliseconds (like the Lorimer burst). At the active stage of the merger, two neutron stars produce a black hole surrounded by an accretion torus in which the magnetic field is amplified to {approx}10{sup 15} G. This magnetic field extracts the rotational energy of the black hole and drives an axially collimated electromagnetic wind that may carry of the order of 10{sup 50} erg, limited by the accretion time of the torus, a few hundred milliseconds. For observers nearly aligned with the orbital normal this is seen as a classical short GRB. After the accretion of the torus, the isolated black hole keeps the open magnetic flux and drives the equatorially (not axially) collimated outflow, which is seen by an observer at intermediate polar angles as a prompt tail. The tail carries more energy than the prompt spike, but its emission is de-boosted for observers along the orbital normal. Observers in the equatorial plane miss the prompt spike

  19. Neutron Radiography

    OpenAIRE

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

    2012-01-01

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

  20. Neutron capture cross section measurement techniques

    International Nuclear Information System (INIS)

    A review of currently-used techniques to measure neutron capture cross sections is presented. Measurements involving use of total absorption and Moxon-Rae detectors are based on low-resolution detection of the prompt γ-ray cascades following neutron captures. In certain energy ranges activation methods are convenient and useful. High resolution γ-ray measurements with germanium detectors can give information on the parameters of resonance capture states. The use of these techniques is described. (U.S.)

  1. Averaging anisotropic cosmologies

    CERN Document Server

    Barrow, J D; Barrow, John D.; Tsagas, Christos G.

    2006-01-01

    We examine the effects of spatial inhomogeneities on irrotational anisotropic cosmologies by looking at the average properties of pressure-free Bianchi-type models. Adopting the Buchert averaging scheme, we identify the kinematic backreaction effects by focussing on spacetimes with zero or isotropic spatial curvature. This allows us to close the system of the standard scalar formulae with a propagation equation for the shear magnitude. We find no change in the already known conditions for accelerated expansion. The backreaction terms are expressed as algebraic relations between the mean-square fluctuations of the models' irreducible kinematical variables. Based on these we investigate the early evolution of averaged vacuum Bianchi type $I$ universes and those filled with pressureless matter. In the latter case we show that the backreaction effects can modify the familiar Kasner-like singularity and potentially remove Mixmaster-type oscillations. We also discuss the possibility of accelerated expansion due to ...

  2. Neutron angular distribution in plutonium-240 spontaneous fission

    Science.gov (United States)

    Marcath, Matthew J.; Shin, Tony H.; Clarke, Shaun D.; Peerani, Paolo; Pozzi, Sara A.

    2016-09-01

    Nuclear safeguards applications require accurate fission models that exhibit prompt neutron anisotropy. In the laboratory reference frame, an anisotropic neutron angular distribution is observed because prompt fission neutrons carry momentum from fully accelerated fission fragments. A liquid organic scintillation detector array was used with pulse shape discrimination techniques to produce neutron-neutron cross-correlation time distributions and angular distributions from spontaneous fission in a 252Cf, a 0.84 g 240Pueff metal, and a 1.63 g 240Pueff metal sample. The effect of cross-talk, estimated with MCNPX-PoliMi simulations, is removed from neutron-neutron coincidences as a function of the angle between detector pairs. Fewer coincidences were observed at detector angles near 90°, relative to higher and lower detector angles. As light output threshold increases, the observed anisotropy increases due to spectral effects arising from fission fragment momentum transfer to emitted neutrons. Stronger anisotropy was observed in Cf-252 spontaneous fission prompt neutrons than in Pu-240 neutrons.

  3. Neutron Noise Measurement at CROCUS

    Energy Technology Data Exchange (ETDEWEB)

    Roland, V.; Perret, G. [Paul Scherrer Institut, Villigen (Switzerland); Girardin, G.; Frajtag, P.; Pautz, A. [Laboratory for Reactor Physics and Systems Behaviour, Lausanne (Switzerland)

    2013-07-01

    This paper reports on the measurements of kinetics parameters at the teaching reactor CROCUS. The prompt decay constant, |α| = (β-ρ)/Λ, was measured in several sub-critical configurations using the Feynman-α reactor noise technique and the reduced generation time Λ/β was deduced. The CROCUS facility is a zero-power reactor operated at EPFL. It is mainly used for educational purposes. Among all neutron noise measurement techniques, the focus was put on the Feynman-α technique. The intrinsic neutron population fluctuations were recorded in macroscopically stable sub-critical states and the prompt decay constants α were derived by fitting the Feynman-α experimental distributions with the point kinetic theoretical expression. The prompt decay constant at critical state α{sub 0}=β/Λ was deduced in two ways: by extrapolation of the sub-critical prompt decay constant to the critical state, and by direct measurement of the sub-critical reactivity using rod-drop techniques. The neutron population was measured by two BF{sub 3} detectors located in the reactor. Data acquisition was performed simultaneously with two ORTEC multichannel scaler cards (MCS-pci) controlled by specially developed LabView programs. The post-processing of the data was done in LabView and Matlab. The prompt decay constant (β/Λ) at criticality was found to be 146.6 ± 6.3 s{sup -1}. Monte Carlo predictions calculated with MCNP5-1.6 are in a good agreement being within 2σ of the experimental results.

  4. Average Angular Velocity

    CERN Document Server

    Essén, H

    2003-01-01

    This paper addresses the problem of the separation of rotational and internal motion. It introduces the concept of average angular velocity as the moment of inertia weighted average of particle angular velocities. It extends and elucidates the concept of Jellinek and Li (1989) of separation of the energy of overall rotation in an arbitrary (non-linear) $N$-particle system. It generalizes the so called Koenig's theorem on the two parts of the kinetic energy (center of mass plus internal) to three parts: center of mass, rotational, plus the remaining internal energy relative to an optimally translating and rotating frame.

  5. On sparsity averaging

    CERN Document Server

    Carrillo, Rafael E; Wiaux, Yves

    2013-01-01

    Recent developments in Carrillo et al. (2012) and Carrillo et al. (2013) introduced a novel regularization method for compressive imaging in the context of compressed sensing with coherent redundant dictionaries. The approach relies on the observation that natural images exhibit strong average sparsity over multiple coherent frames. The associated reconstruction algorithm, based on an analysis prior and a reweighted $\\ell_1$ scheme, is dubbed Sparsity Averaging Reweighted Analysis (SARA). We review these advances and extend associated simulations establishing the superiority of SARA to regularization methods based on sparsity in a single frame, for a generic spread spectrum acquisition and for a Fourier acquisition of particular interest in radio astronomy.

  6. Unintegrated parton distributions and prompt photon hadroproduction

    CERN Document Server

    Kimber, M A; Ryskin, M G

    2000-01-01

    We introduce a general expression which enables the parton distribution, unintegrated over the parton transverse momentum, to be obtained from the conventional parton densities. We use the formalism to study the effects of the transverse momentum q_t of the incoming partonic system on the calculation of the transverse momentum spectra of prompt photons produced in high energy pp and p\\bar{p} collisions. For the purposes of illustration, we use the double logarithm approximation. For large q_t we calculate the effect directly from the perturbative formalism, whereas for small q_t we bound the effect using two extreme hypotheses. In both q_t domains we find that the shapes of the prompt photon spectra are not significantly modified, although the cross sections are enhanced.

  7. Prompt alpha eigenvalue calculations with Tripoli-4

    Science.gov (United States)

    Zoia, Andrea; Brun, Emeric; Malvagi, Fausto

    2014-06-01

    Monte Carlo criticality analyses aimed at determining reactor parameters have been historically based on iterative algorithms whose outcome is the effective multiplication coefficient (keff), i.e., the fundamental eigenvalue of the transport equation. Less attention has been comparatively paid to Monte Carlo algorithms for the estimation of the so-called (prompt) α eigenvalues, which provide information about the (prompt) time evolution of the system. In recent years, this issue has witnessed a renewed interest, mostly due to increased computer power, allowing for reliable and stable search strategies for assessing the fundamental α eigenvalue. In this work, we revisit the theory behind α eigenvalues and propose a Monte Carlo iterative algorithm for the development version of Tripoli-4. In order toillustrate the algorithm, some significant examples are finally discussed.

  8. Prompts, feedback, positive reinforcement, and potty training.

    Science.gov (United States)

    Halligan, Sarah M; Luyben, Paul D

    2009-01-01

    Two parents were concerned because their two young girls were delayed in learning to use the potty. In this study we obtained data on the frequency of wet diapers and use of the potty at home. Following baseline, an intervention was implemented that involved increased intake of liquids and salty foods, prompting, and positive reinforcement. Once a substantial decrease in wet diapers was achieved, together with an increase in use of the potty, the girls were offered the opportunity to wear "Princess Underwear!" as an even more powerful prompt and reinforcer. An ABC design was used with each girl. The results showed significant increases in their use of the potty and decreased incidents of wet diapers when the intervention was in effect. Although this design does not rule out possible effects of coincidences, the data are consistent with the hypothesis that the intervention produced improvements in potty training.

  9. Neutronic measurements of radioactive waste; Les mesures neutroniques des dechets radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Perot, B

    1997-12-31

    This document presents the general matters involved in the radioactive waste management and the different non destructive assays of radioactivity. The neutronic measurements used in the characterization of waste drums containing emitters are described with more details, especially the active neutronic interrogation assays with prompt or delayed neutron detection: physical principle, signal processing and evaluation of the detection limit. (author).

  10. On Averaging Rotations

    DEFF Research Database (Denmark)

    Gramkow, Claus

    2001-01-01

    In this paper two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very often the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong...

  11. A Monte Carlo comparison of PGNAA system performance using 252Cf neutrons, 2.8-MeV neutrons and 14-MeV neutrons

    Science.gov (United States)

    Naqvi, A. A.

    2003-10-01

    Monte Carlo simulations were carried out to compare performance of a 252Cf neutron and a 14-MeV neutron-based prompt γ-ray neutron activation analysis (PGNAA) system with that of the 2.8-MeV neutron-based PGNAA system at King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia. Since the energy of neutron beam used in the KFUPM PGNAA system is very close to that produced by a DD neutron generator, performance comparison between a DD and a DT neutron generator-based PGNAA system is highly desired. For the sake of comparison, the calculations were carried out for the PGNAA system with geometry similar to the KFUPM PGNAA system. These calculations were required to determine improvement in performance of the KFUPM PGNAA system if its 2.8-MeV neutron source is replaced by a 252Cf neutron source or a 14-MeV neutron source. Results of the calculations revealed that the geometry of the 252Cf neutron and the 2.8-MeV neutron-based PGNAA system are not significantly different but the geometry of the 14-MeV neutron-based system is significantly different from that of the 2.8-MeV neutron-based PGNAA system. Accordingly, the prompt γ-ray yields from the 252Cf neutron and the 2.8-MeV neutron-based PGNAA system is comparable but prompt γ-ray yields from 14-MeV neutron-based PGNAA system are about three times smaller than that from the 2.8-MeV neutron-based PGNAA system. This study has shown that performance of the 252Cf neutron-based PGNAA system is comparable with that of the 2.8-MeV neutron-based PGNAA system but the performance of the 14-MeV neutron-based PGNAA system is poorer than that of the 2.8-MeV neutron-based PGNAA system.

  12. A Monte Carlo comparison of PGNAA system performance using {sup 252}Cf neutrons, 2.8-MeV neutrons and 14-MeV neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A. E-mail: aanaqvi@kfupm.edu.sa

    2003-10-01

    Monte Carlo simulations were carried out to compare performance of a {sup 252}Cf neutron and a 14-MeV neutron-based prompt {gamma}-ray neutron activation analysis (PGNAA) system with that of the 2.8-MeV neutron-based PGNAA system at King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia. Since the energy of neutron beam used in the KFUPM PGNAA system is very close to that produced by a DD neutron generator, performance comparison between a DD and a DT neutron generator-based PGNAA system is highly desired. For the sake of comparison, the calculations were carried out for the PGNAA system with geometry similar to the KFUPM PGNAA system. These calculations were required to determine improvement in performance of the KFUPM PGNAA system if its 2.8-MeV neutron source is replaced by a {sup 252}Cf neutron source or a 14-MeV neutron source. Results of the calculations revealed that the geometry of the {sup 252}Cf neutron and the 2.8-MeV neutron-based PGNAA system are not significantly different but the geometry of the 14-MeV neutron-based system is significantly different from that of the 2.8-MeV neutron-based PGNAA system. Accordingly, the prompt {gamma}-ray yields from the {sup 252}Cf neutron and the 2.8-MeV neutron-based PGNAA system is comparable but prompt {gamma}-ray yields from 14-MeV neutron-based PGNAA system are about three times smaller than that from the 2.8-MeV neutron-based PGNAA system. This study has shown that performance of the {sup 252}Cf neutron-based PGNAA system is comparable with that of the 2.8-MeV neutron-based PGNAA system but the performance of the 14-MeV neutron-based PGNAA system is poorer than that of the 2.8-MeV neutron-based PGNAA system.

  13. PROMPT: a protein mapping and comparison tool

    Directory of Open Access Journals (Sweden)

    Frishman Dmitrij

    2006-07-01

    Full Text Available Abstract Background Comparison of large protein datasets has become a standard task in bioinformatics. Typically researchers wish to know whether one group of proteins is significantly enriched in certain annotation attributes or sequence properties compared to another group, and whether this enrichment is statistically significant. In order to conduct such comparisons it is often required to integrate molecular sequence data and experimental information from disparate incompatible sources. While many specialized programs exist for comparisons of this kind in individual problem domains, such as expression data analysis, no generic software solution capable of addressing a wide spectrum of routine tasks in comparative proteomics is currently available. Results PROMPT is a comprehensive bioinformatics software environment which enables the user to compare arbitrary protein sequence sets, revealing statistically significant differences in their annotation features. It allows automatic retrieval and integration of data from a multitude of molecular biological databases as well as from a custom XML format. Similarity-based mapping of sequence IDs makes it possible to link experimental information obtained from different sources despite discrepancies in gene identifiers and minor sequence variation. PROMPT provides a full set of statistical procedures to address the following four use cases: i comparison of the frequencies of categorical annotations between two sets, ii enrichment of nominal features in one set with respect to another one, iii comparison of numeric distributions, and iv correlation of numeric variables. Analysis results can be visualized in the form of plots and spreadsheets and exported in various formats, including Microsoft Excel. Conclusion PROMPT is a versatile, platform-independent, easily expandable, stand-alone application designed to be a practical workhorse in analysing and mining protein sequences and associated annotation

  14. Neutron Skins and Neutron Stars

    OpenAIRE

    Piekarewicz, J

    2013-01-01

    The neutron-skin thickness of heavy nuclei provides a fundamental link to the equation of state of neutron-rich matter, and hence to the properties of neutron stars. The Lead Radius Experiment ("PREX") at Jefferson Laboratory has recently provided the first model-independence evidence on the existence of a neutron-rich skin in 208Pb. In this contribution we examine how the increased accuracy in the determination of neutron skins expected from the commissioning of intense polarized electron be...

  15. The averaging principle

    OpenAIRE

    Fibich, Gadi; Gavious, Arieh; Solan, Eilon

    2012-01-01

    Typically, models with a heterogeneous property are considerably harder to analyze than the corresponding homogeneous models, in which the heterogeneous property is replaced with its average value. In this study we show that any outcome of a heterogeneous model that satisfies the two properties of \\emph{differentiability} and \\emph{interchangibility}, is $O(\\epsilon^2)$ equivalent to the outcome of the corresponding homogeneous model, where $\\epsilon$ is the level of heterogeneity. We then us...

  16. Description of the CAREM Reactor Neutronic Calculation Codes

    International Nuclear Information System (INIS)

    In this work is described the neutronic calculation line used to design the CAREM reactor.A description of the codes used and the interfaces between the different programs are presented.Both, the normal calculation line and the alternative or verification calculation line are included.The calculation line used to obtain the kinetics parameters (effective delayed-neutron fraction and prompt-neutron lifetime) is also included

  17. Prompt gamma analysis of chlorine in concrete for corrosion study.

    Science.gov (United States)

    Naqvi, A A; Nagadi, M M; Al-Amoudi, O S B

    2006-02-01

    Measurement of chlorine in concrete is very important for studying of corrosion of reinforcing steel in concrete. Corrosion of reinforcing steel is primarily ascribed to the penetration of chloride ions to the steel surface. Preventive measures for avoiding concrete structure reinforcement corrosion requires monitoring the chloride ion concentration in concrete so that its concentration does not exceed a threshold limit to initiate reinforcement concrete corrosion. An accelerator based prompt gamma neutron activation analysis (PGNAA) setup has been developed for non-destructive analysis of elemental composition of concrete samples. The setup has been used to measure chlorine concentration in concrete samples over a 1-3 wt% concentration range. Although a strong interference has been observed between the chlorine gamma-rays and calcium gamma-rays from concrete, the chlorine concentration in concrete samples has been successfully measured using the 1.164 and 7.643 MeV chlorine gamma-rays. The experimental data were compared with the results of the Monte Carlo simulations. An excellent agreement has been achieved between the experimental data and results of Monte Carlo simulations. The study has demonstrated the successful use of the accelerator-based PGNAA setup in non-destructive analysis of chlorine in concrete samples. PMID:16129605

  18. Monte Carlo Simulations and prompt gamma measurement for online control of ion therapy

    International Nuclear Information System (INIS)

    During the treatment of a tumor with light ions, the Bragg peak location must be accurately known. A significant fraction of the incident ions undergo nuclear collisions with the target nuclei leading to the prompt emission of particles which may carry information on the ion path. This work, which focuses on prompt gamma, shows that the depth profile of these emissions is highly correlated to the ions path and the measured counting rates allow to consider a realistic imaging system, operating in real time. For that purpose, we performed experiments at GANIL and at GSI with a collimated detector placed perpendicular to the beam axis and the time of flight technique was used in order to reduce the noise induced by neutrons and charged particles. Geant4 simulations were performed for the experimental design and data interpretation. A qualitative agreement between simulations and experiment is observed for the amount of energy deposited in the detector and the shape of the time of flight spectrum. However, discrepancies appear for the prompt gamma yield and the depth distribution of gamma detected. These discrepancies are discussed, mainly in terms of nuclear physics models that must be improved. After selecting the physical models which lead to the best agreement between simulations and measurements, studies on the location of prompt gamma emission and on the influence of diffusion in the target were performed to determine the impact on the correlation with the ion path. (author)

  19. Dose profile monitoring with carbon ions by means of prompt-gamma measurements

    Energy Technology Data Exchange (ETDEWEB)

    Testa, E. [Institut de Physique Nucleaire de Lyon, Universite de Lyon, F-69003 Lyon, Universite Lyon 1 and IN2P3/CNRS, UMR 5822, F-69622 Villeurbanne (France)], E-mail: e.testa@ipnl.in2p3.fr; Bajard, M.; Chevallier, M.; Dauvergne, D.; Le Foulher, F. [Institut de Physique Nucleaire de Lyon, Universite de Lyon, F-69003 Lyon, Universite Lyon 1 and IN2P3/CNRS, UMR 5822, F-69622 Villeurbanne (France); Freud, N.; Letang, J.M. [Institut National des Sciences Appliquees de Lyon, Laboratoire de Controle Non-Destructif par Rayonnements Ionisants (France); Poizat, J.C.; Ray, C.; Testa, M. [Institut de Physique Nucleaire de Lyon, Universite de Lyon, F-69003 Lyon, Universite Lyon 1 and IN2P3/CNRS, UMR 5822, F-69622 Villeurbanne (France)

    2009-03-15

    A key point in the quality control of ion therapy is real-time monitoring and imaging of the dose delivered to the patient. Among the possible signals that can be used to make such a monitoring, prompt gamma-rays issued from nuclear fragmentation are possible candidates, provided the correlation between the emission profile and the primary beam range can be established. By means of simultaneous energy and time-of-flight discrimination, we could measure the longitudinal profile of the prompt gamma-rays emitted by 73 MeV/u carbon ions stopping inside a PMMA target. This technique allowed us to minimize the shielding against neutrons and scattered gamma rays, and to find a good correlation between the prompt-gamma profile and the ion range. This profile was studied as a function of the observation angle. By extrapolating our results to higher energies and realistic detection efficiencies, we showed that prompt gamma-ray measurements make it feasible to control in real time the longitudinal dose during ion therapy treatments.

  20. Neutron reflectometry on highly absorbing films and its application to (B4C)-B-10-based neutron detectors

    OpenAIRE

    Piscitelli, F.; Khaplanov, A.; Devishvili, A.; Schmidt, Susann; Höglund, Carina; Birch, Jens; Dennison, A.J.C.; Gutfreund, P.; Hall-Wilton, R.; van Esch, P.

    2016-01-01

    Neutron reflectometry is a powerful tool used for studies of surfaces and interfaces. In general the absorption in the typical studied materials can be neglected and this technique is limited to the measurement of the reflectivity only. In the case of strongly absorbing nuclei the number of neutrons is not conserved and the absorption can be directly measured by using the neutron-induced fluorescence technique which exploits the prompt particle emission of absorbing isotopes. This technique i...

  1. Constitutive laws for the neutron density current

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa-Paredes, Gilberto [Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186 Col. Vicentina, Mexico, D.F., 09340 (Mexico)], E-mail: gepe@xanum.uam.mx; Morales-Sandoval, Jaime B. [Laboratorio de Analisis en Ingenieria de Reactores Nucleares, Universidad Nacional Autonoma de Mexico, Paseo Cuauhnahuac 8532, 62550 Jiutepec, Mor. (Mexico); Vazquez-Rodriguez, Rodolfo [Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186 Col. Vicentina, Mexico, D.F., 09340 (Mexico); Espinosa-Martinez, Erick-G. [Retorno Quebec 6, Col. Burgos de Cuernavaca 62580, Temixco, Mor. (Mexico)

    2008-10-15

    In this technical note, a fractional wave equation for the average neutron motion in nuclear reactor is considered. This representation covers the full spectrum of the average neutron transport behavior, i.e., Fickian and non-Fickian effects. The fractional diffusion model retains the main dynamic characteristics of the neutron motion in which the relaxation time associated with a rapid variation in the neutron flux contains a fractional exponent that can be manipulated to obtain the best representation of the neutron transport phenomena. The detrended fluctuation analysis (DFA) method is presented in this paper to estimate the fractional exponent.

  2. Prompt photon production in photoproduction at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, Krzysztof

    2010-03-15

    This thesis presents measurement of the production of prompt photons in photoproduction with the H1 experiment at HERA. The analysis is based on the data taken in the years 2004-2007, with a total integrated luminosity of 340 pb{sup -1}. The main difficulty of the measurement comes from the high background of neutral mesons decaying into photons. It is accounted for with the help of multivariate analysis. Prompt photon cross sections are measured with the low negative four-momentum transfer squared Q{sup 2} < 1GeV{sup 2} and in the inelasticity range 0.1 < y < 0.7 for photons with a transverse energy 6 < E{sub T}{sup {gamma}} < 15GeV and in the pseudorapidity range.1.0 < {eta}{sup {gamma}} < 2.4 as a function of photons transverse energy and its pseudorapidity. Cross sections for prompt photon events with an additional hadronic jet are measured as a function of the transverse energy and pseudorapidity of the jet and of the momentum fractions x{sub {gamma}} and x{sub p} of the incident photon and proton carried by the constituents participating in the hard scattering process. Additionally, the transverse correlation between the photon and the jet is studied. The results are compared with predictions of a next-to-leading order calculation and a calculation based on the k{sub T} factorisation approach. Neither of calculations is able to describe all the aspects of the measurement. (orig.)

  3. Radiative Mechanisms in GRB Prompt Emission

    Science.gov (United States)

    Pe'er, A.

    2013-07-01

    Motivated by the Fermi gamma-ray space telescope results, in recent years immense efforts were given to understanding the mechanism that leads to the prompt emission observed. The failure of the optically thin emission models (synchrotron and synchrotron self Compton) increased interest in alternative models. Optically thick models, while having several advantages, also face difficulty in capturing several key observables. Theoretical efforts are focused in two main directions: (1) mechanisms that act to broaden the Planck spectrum; and (2) combining the optically thin and optically thick models to a hybrid model that could explain the key observables.

  4. Radiative Mechanisms in GRB prompt emission

    CERN Document Server

    Pe'er, Asaf

    2013-01-01

    Motivated by the Fermi gamma-ray space telescope results, in recent years immense efforts were given to understanding the mechanism that leads to the prompt emission observed. The failure of the optically thin emission models (synchrotron and synchrotron self Compton) increased interest in alternative models. Optically thick models, while having several advantages, also face difficulty in capturing several key observables. Theoretical efforts are focused in two main directions: (1) mechanisms that act to broaden the Planck spectrum; and (2) combining the optically thin and optically thick models to a hybrid model that could explain the key observables.

  5. Prompt photon production at the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ashish; /SUNY, Stony Brook

    2009-07-01

    Prompt photon production has been studied by the CDF and D0{sup -} experiments at the Fermilab Tevatron collider in p{bar p} collisions at the centre of mass energy of {radical}s = 1.96 TeV. Measurements of the inclusive photon, inclusive photon plus jet, photon plus heavy flavor jet, and diphoton production cross sections are discussed. The analyses use data sample corresponding to integrated luminosity between 0.2 fb{sup -1} and 1.02 fb{sup -1}. The results are compared to the next to leading order (NLO) perturbative QCD (pQCD) calculations.

  6. Prompt Emission Properties of Swift GRBs

    Science.gov (United States)

    Sakamoto, T.; Barthelmy, S.; Baumgartner, W.; Cummings, J.; Fenimore, E.; Gehrels, N.; Krimm, H.; Markwardt, Craig B.; Palmer, D.; Parsons, A.; Sato, G.; Stamatikos, M.; Tueller, J.; Ukwatta, T.

    2010-01-01

    We present the results from the second Swift BAT catalog of 476 gamma-ray bursts, which contains bursts detected by the BAT between 2004 December 19 and 2009 December 21. In addition to the spectral and temporal parameters extracted from the first BAT GRB catalog, 3324 time-resolved spectra have been extracted and analyzed. We show and discuss 1) the duration distribution, 2) the hardness of short GRBs, 3) Epeak distribution, 4) the line of death problem and 5) an additional power-law component in the prompt emission spectrum.

  7. Prompt Emission Observations of Swift BAT Bursts

    Science.gov (United States)

    Barthelmy, Scott

    2009-01-01

    We review the prompt emission properties of Swift BAT gamma-ray bursts (GRBs). We present the global properties of BAT GRBs based on their spectral and temporal characteristics. The BAT T90 and T50 durations peak at 80 and 20 s, respectively. The peak energy (Epeak) of about 60% of BAT GRBs is very likely to be less than 1.00 keV. We also present the BAT characteristics of GRBs with soft spectra, so called Xray flashes (XRFs). We will compare the BAT GRBs and XRFs parameter distribution to the other missions.

  8. Lipid rescue in children: The prompt decision.

    Science.gov (United States)

    Eizaga Rebollar, Ramón; García Palacios, María V; Morales Guerrero, Javier; Torres Morera, Luis M

    2016-08-01

    We report the case of a 17-month-old child who underwent laparotomy under general anesthesia and caudal block. Electrocardiogram ST-T changes were observed after local anesthetic injection. The prompt use of Intralipid 30% was successful in normalizing ECG alterations. Our experience is consistent with previous literature, mainly carried out in adults. Thereby, we conduct a brief review of the subject in pediatrics. As a major conclusion, we strongly recommend the "fast-track" lipid rescue as soon as this severe complication is detected. PMID:27290983

  9. Feasibility study for the quantification of total protein content by multiple prompt gamma-ray analysis

    Energy Technology Data Exchange (ETDEWEB)

    Toh, Y., E-mail: toh.yosuke@jaea.go.jp [Japan Atomic Energy Agency, Nuclear Science and Engineering Directorate, Tokai, Naka, Ibaraki 319-1195 (Japan); Murakami, Y. [University of Fukui, Research Institute of Nuclear Engineering, 3-9-1 Bunkyo, Fukui City, Fukui 910-8507 (Japan); Furutaka, K.; Kimura, A.; Koizumi, M.; Hara, K.; Kin, T.; Nakamura, S.; Harada, H. [Japan Atomic Energy Agency, Nuclear Science and Engineering Directorate, Tokai, Naka, Ibaraki 319-1195 (Japan)

    2012-06-15

    Protein is an important nutrient in foods. The classical nitrogen analysis method is the Kjeldahl technique, which is time-consuming and inconvenient. As a convenient method to quantify protein content in biological samples, the feasibility of application of multiple prompt gamma-ray analysis (MPGA) to the quantification was studied. Results for protein content are reported for several reference materials and prove the method to be reliable. - Highlights: Black-Right-Pointing-Pointer Nitrogen contents were analyzed by multiple prompt gamma-ray analysis. Black-Right-Pointing-Pointer The effect of neutron scattering was evaluated by Monte Carlo simulation. Black-Right-Pointing-Pointer Protein content can be calculated by nitrogen content. Black-Right-Pointing-Pointer The protein contents of standard materials agreed with the certified values. Black-Right-Pointing-Pointer The method is a rapid, non-destructive, feasible method to quantify protein.

  10. Neutron-gamma competition for $\\beta$-delayed neutron emission

    CERN Document Server

    Mumpower, Matthew; Moller, Peter

    2016-01-01

    We present a coupled Quasi-particle Random Phase Approximation and Hauser-Feshbach (QRPA+HF) model for calculating delayed particle emission. This approach uses microscopic nuclear structure information which starts with Gamow-Teller strength distributions in the daughter nucleus, and then follows the statistical decay until the initial available excitation energy is exhausted. Explicitly included at each particle emission stage is $\\gamma$-ray competition. We explore this model in the context of neutron emission of neutron-rich nuclei and find that neutron-gamma competition can lead to both increases and decreases in neutron emission probabilities, depending on the system considered. A second consequence of this formalism is a prediction of more neutrons on average being emitted after $\\beta$-decay for nuclei near the neutron dripline compared to models that do not consider the statistical decay.

  11. Negative Average Preference Utilitarianism

    Directory of Open Access Journals (Sweden)

    Roger Chao

    2012-03-01

    Full Text Available For many philosophers working in the area of Population Ethics, it seems that either they have to confront the Repugnant Conclusion (where they are forced to the conclusion of creating massive amounts of lives barely worth living, or they have to confront the Non-Identity Problem (where no one is seemingly harmed as their existence is dependent on the “harmful” event that took place. To them it seems there is no escape, they either have to face one problem or the other. However, there is a way around this, allowing us to escape the Repugnant Conclusion, by using what I will call Negative Average Preference Utilitarianism (NAPU – which though similar to anti-frustrationism, has some important differences in practice. Current “positive” forms of utilitarianism have struggled to deal with the Repugnant Conclusion, as their theory actually entails this conclusion; however, it seems that a form of Negative Average Preference Utilitarianism (NAPU easily escapes this dilemma (it never even arises within it.

  12. Supporting Self-Regulated Hypermedia Learning through Prompts

    Science.gov (United States)

    Bannert, Maria; Reimann, Peter

    2012-01-01

    The aim of this research was to develop and evaluate tools and supports for self-regulated learning with hypertext information structures, such as Web pages. Two kinds of supports for self-regulated learning were developed and tested experimentally: Prompting and Prompting with Training. In Experiment 1, Prompting was tested with a pre-post-test…

  13. Neutron Radiography

    Directory of Open Access Journals (Sweden)

    A. R. Reddy

    1982-07-01

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

  14. Neutrons from medical electron accelerators

    International Nuclear Information System (INIS)

    The significant sources of photoneutrons within a linear-accelerator treatment head are identified and absolute estimates of neutron production per treatment dose are given for typical components. Measured data obtained at a variety of accelerator installations are presented and compared with these calculations. It is found that the high-Z materials within the treatment head do not significantly alter the neutron fluence, but do substantially reduce the average energy of the transmitted spectrum. Reflected neutrons from the concrete treatment room contribute to the neutron fluence, but not substantially to the patient integral dose, because of a further reduction in average energy. Absolute depth-dose distributions for realistic neutron spectra are calculated, and a rapid falloff with depth is found

  15. Design and Construct of In-Hospital Neutron Irradiator

    International Nuclear Information System (INIS)

    The In-hospital neutron irradiator (IHNI) is designed based on the design of the Miniature Neutron Source Reactor (MNSR) for boron neutron capture therapy (BNCT), NAA, physics experiments, training and teaching. The reactor of the IHNI with thermal power 30 kW is an undermoderated reactor of pool-tank type, UO2 with enrichment of 12.5% as fuel, light water as coolant and moderator, and metal beryllium as reflector. The fission heat produced by the reactor is removed by the natural circulation. On the both sides of the reactor core, there are two neutron beams, one is a thermal neutron beam, and the other, opposite to the thermal beam, is an epithermal neutron beam. An experimental thermal neutron beam is specially designed for the prompt gamma neutron activation analysis (PGNAA). In this paper, the design and experiment results of IHNI will be introduced. (author)

  16. Calculation and consideration of the experimental correction factor of the prompt ko-factors for the development of the PGNAA database

    International Nuclear Information System (INIS)

    The prompt ko-factors are calculated for the light elements(Ao-factor, correction factor is derived for the case of the incident neutron spectrum containing epithermal component. For non-1/v absorbers, the correction factor is discussed in terms of the Westcott g-factors of the standard and comparator isotopes. Finally, the correction factor is derived for the polychromatic neutron beam of the PGNAA system in HANARO

  17. The University of Texas Cold Neutron Source

    Science.gov (United States)

    Ünlü, Kenan; Ríos-Martínez, Carlos; Wehring, Bernard W.

    1994-12-01

    A cold neutron source has been designed, constructed, and tested by the Nuclear Engineering Teaching Laboratory (NETL) at The University of Texas at Austin. The Texas Cold Neutron Source (TCNS) is located in one of the beam ports of the NETL 1-MW TRIGA Mark II research reactor. The main components of the TCNS are a cooled moderator, a heat pipe, a cryogenic refrigerator, and a neutron guide. 80 ml of mesitylene moderator are maintained at about 30 K in a chamber within the reactor graphite reflector by the heat pipe and cryogenic refrigerator. The heat pipe is a 3-m long aluminum tube that contains neon as the working fluid. The cold neutrons obtained from the moderator are transported by a curved 6-m long neutron guide. This neutron guide has a radius of curvature of 300 m, a 50 × 15 mm cross-section, 58Ni coating, and is separated into three channels. The TCNS will provide a low-background subthermal neutron beam for neutron capture and scattering research. After the installation of the external portion of the neutron guide, a neutron focusing system and a Prompt Gamma Activation Analysis facility will be set up at the TCNS.

  18. Fission prompt gamma-ray multiplicity distribution measurements and simulations at DANCE

    Energy Technology Data Exchange (ETDEWEB)

    Chyzh, A; Wu, C Y; Ullmann, J; Jandel, M; Bredeweg, T; Couture, A; Norman, E

    2010-08-24

    The nearly energy independence of the DANCE efficiency and multiplicity response to {gamma} rays makes it possible to measure the prompt {gamma}-ray multiplicity distribution in fission. We demonstrate this unique capability of DANCE through the comparison of {gamma}-ray energy and multiplicity distribution between the measurement and numerical simulation for three radioactive sources {sup 22}Na, {sup 60}Co, and {sup 88}Y. The prospect for measuring the {gamma}-ray multiplicity distribution for both spontaneous and neutron-induced fission is discussed.

  19. Neutron Capture and Neutron Halos

    OpenAIRE

    A.Mengoni; Otsuka, T; Nakamura, T.(International Center for Elementary Particle Physics and Department of Physics, The University of Tokyo, Tokyo, Japan); Ishihara, M.

    1996-01-01

    The connection between the neutron halo observed in light neutron rich nuclei and the neutron radiative capture process is outlined. We show how nuclear structure information such as spectroscopic factors and external components of the radial wave function of loosely bound states can be derived from the neutron capture cross section. The link between the direct radiative capture and the Coulomb dissociation process is elucidated.

  20. Compact Neutron Generators for Medical, Home Land Security, and Planetary Exploration

    CERN Document Server

    Reijonen, Jani

    2005-01-01

    The Plasma and Ion Source Technology Group at Lawrence Berkeley National Laboratory has developed various types of advanced D-D (neutron energy 2.5 MeV), D-T (14 MeV) and T-T (0 - 9 MeV) neutron generators for wide range of applications. These applications include medical (Boron Neutron Capture Therapy), homeland security (Prompt Gamma Activation Analysis, Fast Neutron Activation Analysis and Pulsed Fast Neutron Transmission Spectroscopy) and planetary exploration in form of neutron based, sub-surface hydrogen detection systems. These neutron generators utilize RF induction discharge to ionize the deuterium/tritium gas. This discharge method provides high plasma density for high output current, high atomic species from molecular gases, long life operation and versatility for various discharge chamber geometries. Three main neutron generator developments are discussed here: high neutron output co-axial neutron generator for BNCT applications, point neutron generator for security applications, compact and sub-c...

  1. Passive neutron dosemeter design

    International Nuclear Information System (INIS)

    A passive neutron dosemeter was designed to be used in mixed radiation fields. The design was carried out using Monte Carlo method. The dosemeter model was a 25.4 cm-diameter polyethylene sphere with a thermoluminescent dosemeter, TLD600, located at the sphere center. This model was irradiated with 50 monoenergetic neutron sources with energies from 10-8 to 20 MeV. A 506.71 cm2-area disk was used to model the source term whose center was located at 100 cm from polyethylene sphere's center. The dosemeter response was compared with the responses of SNOOPY, Harwell 95/0075 and PNR-4. With these responses it was calculated the dosemeter responses for 252Cf, 252Cf/D2O and 239PuBe neutron sources. The passive dosemeter relative response has the same shape of SNOOPY, Harwell 95/0075 and PNR-4 dosemeters. Due to the type of thermal neutron detector used in the passive dosemeter the absolute response per unit fluence, is lower than the absolute response of SNOOPY, Harwell 95/0075 and PNR-4 dosemeters. However the passive dosemeter response in function of the average neutron energy of the 252Cf, 252Cf/D2O and 239PuBe neutron energy was more linear

  2. Neutron capture therapy

    International Nuclear Information System (INIS)

    The overall state of the art related with neutron capture therapy(NCT) is surveyed. Since the field related with NCT is very wide, it is not intended to survey all related subjects in depth. The primary objective of this report is to help those working for the installation of a NCT facility and a PGNAA(prompt gamma ray neutron activation analysis) system for the boron analysis understand overall NCT at Hanaro. Therefore, while the parts of reactor neutron source and PGNAA are dealt in detail, other parts are limited to the level necessary to understand related fields. For example, the subject of chemical compound which requires intensive knowledge on chemistry, is not dealt as a separated item. However, the requirement of a compound for NCT, currently available compounds, their characteristics, etc. could be understood through this report. Although the subject of cancer treated by NCT is out of the capability of the author, it is dealt focussing its characteristics related with the success of NCT. Each detailed subject is expected to be dealt more detail by specialists in future. This report would be helpful for the researchers working for the NCT to understand related fields. (author). 128 refs., 3 tabs., 12 figs

  3. Neutron interrogation of actinides with a 17 MeV electron accelerator and first results from photon and neutron interrogation non-simultaneous measurements combination

    Energy Technology Data Exchange (ETDEWEB)

    Sari, A., E-mail: adrien.sari@cea.fr [CEA, LIST, Laboratoire Capteurs et Architectures Electroniques, 91191 Gif-sur-Yvette Cedex (France); Carrel, F.; Lainé, F. [CEA, LIST, Laboratoire Capteurs et Architectures Electroniques, 91191 Gif-sur-Yvette Cedex (France); Lyoussi, A. [CEA, DEN, 13108 Saint-Paul-Lez-Durance Cedex (France)

    2013-10-01

    In this article, we demonstrate the feasibility of neutron interrogation using the conversion target of a 17 MeV linear electron accelerator as a neutron generator. Signals from prompt neutrons, delayed neutrons, and delayed gamma-rays, emitted by both uranium and plutonium samples were analyzed. First results from photon and neutron interrogation non-simultaneous measurements combination are also reported in this paper. Feasibility of this technique is shown in the frame of the measurement of uranium enrichment. The latter was carried out by combining detection of prompt neutrons from thermal fission and delayed neutrons from photofission, and by combining delayed gamma-rays from thermal fission and delayed gamma-rays from photofission.

  4. Investigation of forming mechanism of instantaneous neutron spectrum of 235U, 239Pu, 252Cf nuclei fission

    International Nuclear Information System (INIS)

    Formation mechanism of prompt neutrons spectrum during the fission of the 235U, 239Pu nuclei by thermal and fast neutrons and spontaneous fission of 252Cf is investigated. The formation procedure for prompt neutrons spectrum during the fission of nuclei as superposition of three partial evaporation Weisskopf spectra with the mean energy of neutrons 0.4, 2.06 and 2.8 MeV is proposed. Formation mechanism of the spectrum just as during the fission of the 235U, 239Pu nuclei by thermal and fast neutrons, so spontaneous fission of the 252Cf nuclei is identical

  5. Prompt Photons in Photoproduction at HERA

    CERN Document Server

    Aaron, F D; Alexa, C; Andreev, V; Antunovic, B; Backovic, S; Baghdasaryan, A; Barrelet, E; Bartel, W; Begzsuren, K; Belousov, A; Bizot, J C; Boudry, V; Bozovic-Jelisavcic, I; Bracinik, J; Brandt, G; Brinkmann, M; Brisson, V; Bruncko, D; Bunyatyan, A; Buschhorn, G; Bystritskaya, L; Campbell, A J; Cantun Avila, K B; Cerny, K; Cerny, V; Chekelian, V; Cholewa, A; Contreras, J G; Coughlan, J A; Cozzika, G; Cvach, J; Dainton, J B; Daum, K; Deak, M; de Boer, Y; Delcourt, B; Del Degan, M; Delvax, J; De Wolf, E A; Diaconu, C; Dodonov, V; Dossanov, A; Dubak, A; Eckerlin, G; Efremenko, V; Egli, S; Eliseev, A; Elsen, E; Falkiewicz, A; Favart, L; Fedotov, A; Felst, R; Feltesse, J; Ferencei, J; Fischer, D J; Fleischer, M; Fomenko, A; Gabathuler, E; Gayler, J; Ghazaryan, S; Glazov, A; Glushkov, I; Goerlich, L; Gogitidze, N; Gouzevitch, M; Grab, C; Greenshaw, T; Grell, B R; Grindhammer, G; Habib, S; Haidt, D; Helebrant, C; Henderson, R C.W; Hennekemper, E; Henschel, H; Herbst, M; Herrera, G; Hildebrandt, M; Hiller, K H; Hoffmann, D; Horisberger, R; Hreus, T; Jacquet, M; Janssen, X; Jonsson, L; Jung, A W; Jung, H; Kapichine, M; Katzy, J; Kenyon, I R; Kiesling, C; Klein, M; Kleinwort, C; Kluge, T; Knutsson, A; Kogler, R; Kostka, P; Kraemer, M; Krastev, K; Kretzschmar, J; Kropivnitskaya, A; Kruger, K; Kutak, K; Landon, M P.J; Lange, W; Lastovicka-Medin, G; Laycock, P; Lebedev, A; Leibenguth, G; Lendermann, V; Levonian, S; Li, G; Lipka, K; Liptaj, A; List, B; List, J; Loktionova, N; Lopez-Fernandez, R; Lubimov, V; Makankine, A; Malinovski, E; Marage, P; Marti, Ll; Martyn, H U; Maxfield, S J; Mehta, A; Meyer, A B; Meyer, H; Meyer, H; Meyer, J; Michels, V; Mikocki, S; Milcewicz-Mika, I; Moreau, F; Morozov, A; Morris, J V; Mozer, M U; Mudrinic, M; Muller, K; Murin, P; Naumann, Th; Newman, P R; Niebuhr, C; Nikiforov, A; Nikitin, D; Nowak, G; Nowak, K; Nozicka, M; Olivier, B; Olsson, J E; Osman, S; Ozerov, D; Palichik, V; Panagoulias, I; Pandurovic, M; Papadopoulou, Th; Pascaud, C; Patel, G D; Pejchal, O; Perez, E; Petrukhin, A; Picuric, I; Piec, S; Pitzl, D; Placakyte, R; Pokorny, B; Polifka, R; Povh, B; Radescu, V; Rahmat, A J; Raicevic, N; Raspiareza, A; Ravdandorj, T; Reimer, P; Rizvi, E; Robmann, P; Roland, B; Roosen, R; Rostovtsev, A; Rotaru, M; Ruiz Tabasco, J E; Rurikova, Z; Rusakov, S; Salek, D; Sankey, D P.C; Sauter, M; Sauvan, E; Schmitt, S; Schoeffel, L; Schoning, A; Schultz-Coulon, H C; Sefkow, F; Shaw-West, R N; Shtarkov, L N; Shushkevich, S; Sloan, T; Smiljanic, I; Soloviev, Y; Sopicki, P; South, D; Spaskov, V; Specka, A; Staykova, Z; Steder, M; Stella, B; Stoicea, G; Straumann, U; Sunar, D; Sykora, T; Tchoulakov, V; Thompson, G; Thompson, P D; Toll, T; Tomasz, F; Tran, T H; Traynor, D; Trinh, T N; Truol, P; Tsakov, I; Tseepeldorj, B; Turnau, J; Urban, K; Valkarova, A; Vallee, C; Van Mechelen, P; Vargas Trevino, A; Vazdik, Y; Vinokurova, S; Volchinski, V; von den Driesch, M; Wegener, D; Wissing, Ch; Wunsch, E; Zacek, J; Zalesak, J; Zhang, Z; Zhokin, A; Zimmermann, T; Zohrabyan, H; Zomer, F; Zus, R

    2010-01-01

    The production of prompt photons is measured in the photoproduction regime of electron-proton scattering at HERA. The analysis is based on a data sample corresponding to a total integrated luminosity of 340 pb^-1 collected by the H1 experiment. Cross sections are measured for photons with transverse momentum and pseudorapidity in the range 6 < Et < 15 GeV and -1.0 < eta < 2.4, respectively. Cross sections for events with an additional jet are measured as a function of the transverse energy and pseudorapidity of the jet, and as a function of the fractional momenta x_gamma and x_p carried by the partons entering the hard scattering process. The correlation between the photon and the jet is also studied. The results are compared with QCD predictions based on the collinear and on the k_T factorisation approaches.

  6. Fast Neutron Induced Fission neutron Spectra Below the Incident Energy

    Energy Technology Data Exchange (ETDEWEB)

    Woodring, Mitchell L.; Egan, James J.; Kegel, Gunter H.; DeSimone, David J.

    2008-06-15

    Fission neutron spectra from neutron induced fission in 235U and 239Pu for energies below that of the neutron inducing fission have been measured. The spectra were obtained for 1.5 MeV and 2.5 MeV incident neutrons. Previous accelerator-based fission neutron spectra measurements have been seriously complicated by time-correlated gamma rays and scattered neutrons from the fission sample. Three barium fluoride detectors were placed near the sample undergoing induced fission and used to identify fission gamma rays. A coincidence of fission gamma rays was used to gate a liquid scintillator neutron detector to distinguish fission events from other events. The fission neutron spectral shape and average energy measured in this experiment compare well to both previous measurements and prior theory and also suggest a dependence on incident neutron energy and mass of the fissioning nucleus. An overview of the experiment, a discussion of the results, and the importance of this work to homeland security are given.

  7. Method of measuring thermal neutron characteristics

    International Nuclear Information System (INIS)

    The thermal neutron decay characteristics of an earth formation are measured by detecting indications of the thermal neutron concentration in the formation during first and second measurement intervals following irradiation of the formation with a burst of fast neutrons. These measurement intervals may be selected from a sequence of discrete time gates which begins following a predetermined time delay after the preceding neutron burst and extends over substantially the remainder of the interval between neutron bursts. The particular set of two measurement intervals used is selected from among a number of possible sets as a function of a previously measured value of the decay characteristic. Measurements of detected radiation, averaged over a plurality of first intervals following respective neutron bursts, and averaged over a greater plurality of second intervals, are used to provide a background-compensated measure of the average level of induced radiation. (author)

  8. Neutron detector

    Science.gov (United States)

    Stephan, Andrew C.; Jardret; Vincent D.

    2011-04-05

    A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

  9. Dissociating Averageness and Attractiveness: Attractive Faces Are Not Always Average

    Science.gov (United States)

    DeBruine, Lisa M.; Jones, Benedict C.; Unger, Layla; Little, Anthony C.; Feinberg, David R.

    2007-01-01

    Although the averageness hypothesis of facial attractiveness proposes that the attractiveness of faces is mostly a consequence of their averageness, 1 study has shown that caricaturing highly attractive faces makes them mathematically less average but more attractive. Here the authors systematically test the averageness hypothesis in 5 experiments…

  10. Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture

    Energy Technology Data Exchange (ETDEWEB)

    Scott Wilde, Raymond Keegan

    2008-07-01

    The countrate response of a gamma spectrometry system from a neutron radiation source behind a plane of moderating material doped with a nuclide of a large radiative neutron capture cross-section exhibits a countrate response analogous to a gamma radiation source at the same position from the detector. Using a planar, surface area of the neutron moderating material exposed to the neutron radiation produces a larger area under the prompt gamma ray peak in the detector than a smaller area of dimensions relative to the active volume of the gamma detection system.

  11. Enhancing the detector for advanced neutron capture experiments

    International Nuclear Information System (INIS)

    The Detector for Advanced Neutron Capture Experiments (DANCE) has been used for extensive studies of neutron capture, gamma decay, photon strength functions, and prompt and delayed fission-gamma emission. Despite these successes, the potential measurements have been limited by the data acquisition hardware. We report on a major upgrade of the DANCE data acquisition that simultaneously enables strait-forward coupling to auxiliary detectors, including high-resolution high-purity germanium detectors and neutron tagging array. The upgrade will enhance the time domain accessible for time-of-flight neutron measurements as well as improve the resolution in the DANCE barium fluoride crystals for photons

  12. Gadolinium-neutron capture reactions: A radiobiological assay

    International Nuclear Information System (INIS)

    Gadolinium neutron capture(GNC) takes advantage of its extraordinarily large cross section to thermal neutrons. In GNC reactions, prompt high energy gamma rays, x-rays and electrons are released. Because of the photons and electrons, the intracellular presence of gadolinium is not considered critical. This is an advantage over boron-neutron capture therapy where the intracellular presence of boron is required because of the short flight tracks of 2.4 MeV alpha particles. In this study, the radiation effect of GNC reactions was measured using Chinese hamster cells in an attempt to evaluate the contributions of neutrons, gamma rays and electrons on cell inactivation

  13. Atmospheric neutrons

    International Nuclear Information System (INIS)

    Additional calibrations of the University of California double-scatter neutron and additional analysis corrections lead to the slightly changed neutron fluxes reported here. The theoretical angular distributions of Merker (1975) are in general agreement with our experimental fluxes but do not give the peaks for vertical upward and downward moving neutrons. The theoretical neutron escape current J2/sub pi/ (Merker, 1972; Armstrong et al., 1973) is in agreement with the experimental values from 10 to 100 MeV. Our experimental fluxes agree with those of the Kanbach et al. (1974) in the overlap region from 70 to 100 MeV

  14. Neutron Albedo

    CERN Document Server

    Ignatovich, V K

    2005-01-01

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

  15. Strategies for Finding Prompt Radio Counterparts to Gravitational Wave Transients with the Murchison Widefield Array

    Science.gov (United States)

    Kaplan, D. L.; Murphy, T.; Rowlinson, A.; Croft, S. D.; Wayth, R. B.; Trott, C. M.

    2016-10-01

    Wepresent and evaluate several strategies to search for prompt, low-frequency radio emission associated with gravitational wave transients using the Murchison Widefield Array. As we are able to repoint the Murchison Widefield Array on timescales of tens of seconds, we can search for the dispersed radio signal that has been predicted to originate along with or shortly after a neutron star-neutron star merger. We find that given the large, 600 deg2 instantaneous field of view of the Murchison Widefield Array, we can cover a significant fraction of the predicted gravitational wave error region, although due to the complicated geometry of the latter, we only cover > 50% of the error region for approximately 5% of events, and roughly 15% of events will be located < 10° from the Murchison Widefield Array pointing centre such that they will be covered in the radio images. For optimal conditions, our limiting flux density for a 10-s long transient would be 0.1 Jy, increasing to about 1 Jy for a wider range of events. This corresponds to luminosity limits of 1038-39 erg s-1 based on expectations for the distances of the gravitational wave transients, which should be sufficient to detect or significantly constrain a range of models for prompt emission.

  16. Prompt Planetesimal Formation beyond the Snow Line

    Science.gov (United States)

    Armitage, Philip J.; Eisner, Josh A.; Simon, Jacob B.

    2016-09-01

    We develop a simple model to predict the radial distribution of planetesimal formation. The model is based on the observed growth of dust to millimeter-sized particles, which drift radially, pile-up, and form planetesimals where the stopping time and dust-to-gas ratio intersect the allowed region for streaming instability-induced gravitational collapse. Using an approximate analytic treatment, we first show that drifting particles define a track in metallicity–stopping time space whose only substantial dependence is on the disk’s angular momentum transport efficiency. Prompt planetesimal formation is feasible for high particle accretion rates (relative to the gas, {\\dot{M}}p/\\dot{M}≳ 3× {10}-2 for α ={10}-2), which could only be sustained for a limited period of time. If it is possible, it would lead to the deposition of a broad and massive belt of planetesimals with a sharp outer edge. Numerically including turbulent diffusion and vapor condensation processes, we find that a modest enhancement of solids near the snow line occurs for centimeter-sized particles, but that this is largely immaterial for planetesimal formation. We note that radial drift couples planetesimal formation across radii in the disk, and suggest that considerations of planetesimal formation favor a model in which the initial deposition of material for giant planet cores occurs well beyond the snow line.

  17. Prompt Planetesimal Formation beyond the Snow Line

    Science.gov (United States)

    Armitage, Philip J.; Eisner, Josh A.; Simon, Jacob B.

    2016-09-01

    We develop a simple model to predict the radial distribution of planetesimal formation. The model is based on the observed growth of dust to millimeter-sized particles, which drift radially, pile-up, and form planetesimals where the stopping time and dust-to-gas ratio intersect the allowed region for streaming instability-induced gravitational collapse. Using an approximate analytic treatment, we first show that drifting particles define a track in metallicity-stopping time space whose only substantial dependence is on the disk’s angular momentum transport efficiency. Prompt planetesimal formation is feasible for high particle accretion rates (relative to the gas, {\\dot{M}}p/\\dot{M}≳ 3× {10}-2 for α ={10}-2), which could only be sustained for a limited period of time. If it is possible, it would lead to the deposition of a broad and massive belt of planetesimals with a sharp outer edge. Numerically including turbulent diffusion and vapor condensation processes, we find that a modest enhancement of solids near the snow line occurs for centimeter-sized particles, but that this is largely immaterial for planetesimal formation. We note that radial drift couples planetesimal formation across radii in the disk, and suggest that considerations of planetesimal formation favor a model in which the initial deposition of material for giant planet cores occurs well beyond the snow line.

  18. Prompt planetesimal formation beyond the snow line

    CERN Document Server

    Armitage, Philip J; Simon, Jacob B

    2016-01-01

    We develop a simple model to predict the radial distribution of planetesimal formation. The model is based on the observed growth of dust to mm-sized particles, which drift radially, pile-up, and form planetesimals where the stopping time and dust-to-gas ratio intersect the allowed region for streaming instability-induced gravitational collapse. Using an approximate analytic treatment, we first show that drifting particles define a track in metallicity--stopping time space whose only substantial dependence is on the disk's angular momentum transport efficiency. Prompt planetesimal formation is feasible for high particle accretion rates (relative to the gas, $\\dot{M}_p / \\dot{M} > 3 \\times 10^{-2}$ for $\\alpha = 10^{-2}$), that could only be sustained for a limited period of time. If it is possible, it would lead to the deposition of a broad and massive belt of planetesimals with a sharp outer edge. Including turbulent diffusion and vapor condensation processes numerically, we find that a modest enhancement of...

  19. Virtual Averaging Making Nonframe-Averaged Optical Coherence Tomography Images Comparable to Frame-Averaged Images

    OpenAIRE

    Chen, Chieh-Li; Ishikawa, Hiroshi; Wollstein, Gadi; Bilonick, Richard A.; Kagemann, Larry; Schuman, Joel S.

    2016-01-01

    Purpose Developing a novel image enhancement method so that nonframe-averaged optical coherence tomography (OCT) images become comparable to active eye-tracking frame-averaged OCT images. Methods Twenty-one eyes of 21 healthy volunteers were scanned with noneye-tracking nonframe-averaged OCT device and active eye-tracking frame-averaged OCT device. Virtual averaging was applied to nonframe-averaged images with voxel resampling and adding amplitude deviation with 15-time repetitions. Signal-to...

  20. A Monte Carlo simulation and setup optimization of output efficiency to PGNAA thermal neutron using 252Cf neutrons

    Science.gov (United States)

    Zhang, Jin-Zhao; Tuo, Xian-Guo

    2014-07-01

    We present the design and optimization of a prompt γ-ray neutron activation analysis (PGNAA) thermal neutron output setup based on Monte Carlo simulations using MCNP5 computer code. In these simulations, the moderator materials, reflective materials, and structure of the PGNAA 252Cf neutrons of thermal neutron output setup are optimized. The simulation results reveal that the thin layer paraffin and the thick layer of heavy water moderating effect work best for the 252Cf neutron spectrum. Our new design shows a significantly improved performance of the thermal neutron flux and flux rate, that are increased by 3.02 times and 3.27 times, respectively, compared with the conventional neutron source design.

  1. Prompt processes in heavy ion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Blann, M.; Remington, B.A.

    1987-12-01

    We test a relaxation model based on two body nucleon-nucleon scattering processes to interpret phenomena observed in heavy ion reactions. We use the Boltzmann Master Equation to accomplish this. By assuming that the projectile nucleons partition the total excitation with equal a-priori probability of all configurations, we are able to reproduce several sets of neutron spectra from /sup 20/Ne and /sup 12/C induced reactions on /sup 165/Ho and from reactions of /sup 40/Ar or /sup 40/Ca. We point out ambiguities in deducing angle-integrated energy spectra from double differential spectra. With no additional free parameters, our model successfully reproduces a large body of high energy ..gamma..-ray spectra by assuming an incoherent n-p-bremsstrahlung mechanism. 45 refs., 13 figs.

  2. Radiative neutron capture as a counting technique at pulsed spallation neutron sources: a review of current progress

    Science.gov (United States)

    Schooneveld, E. M.; Pietropaolo, A.; Andreani, C.; Perelli Cippo, E.; Rhodes, N. J.; Senesi, R.; Tardocchi, M.; Gorini, G.

    2016-09-01

    Neutron scattering techniques are attracting an increasing interest from scientists in various research fields, ranging from physics and chemistry to biology and archaeometry. The success of these neutron scattering applications is stimulated by the development of higher performance instrumentation. The development of new techniques and concepts, including radiative capture based neutron detection, is therefore a key issue to be addressed. Radiative capture based neutron detectors utilize the emission of prompt gamma rays after neutron absorption in a suitable isotope and the detection of those gammas by a photon counter. They can be used as simple counters in the thermal region and (simultaneously) as energy selector and counters for neutrons in the eV energy region. Several years of extensive development have made eV neutron spectrometers operating in the so-called resonance detector spectrometer (RDS) configuration outperform their conventional counterparts. In fact, the VESUVIO spectrometer, a flagship instrument at ISIS serving a continuous user programme for eV inelastic neutron spectroscopy measurements, is operating in the RDS configuration since 2007. In this review, we discuss the physical mechanism underlying the RDS configuration and the development of associated instrumentation. A few successful neutron scattering experiments that utilize the radiative capture counting techniques will be presented together with the potential of this technique for thermal neutron diffraction measurements. We also outline possible improvements and future perspectives for radiative capture based neutron detectors in neutron scattering application at pulsed neutron sources.

  3. Radiative neutron capture as a counting technique at pulsed spallation neutron sources: a review of current progress.

    Science.gov (United States)

    Schooneveld, E M; Pietropaolo, A; Andreani, C; Perelli Cippo, E; Rhodes, N J; Senesi, R; Tardocchi, M; Gorini, G

    2016-09-01

    Neutron scattering techniques are attracting an increasing interest from scientists in various research fields, ranging from physics and chemistry to biology and archaeometry. The success of these neutron scattering applications is stimulated by the development of higher performance instrumentation. The development of new techniques and concepts, including radiative capture based neutron detection, is therefore a key issue to be addressed. Radiative capture based neutron detectors utilize the emission of prompt gamma rays after neutron absorption in a suitable isotope and the detection of those gammas by a photon counter. They can be used as simple counters in the thermal region and (simultaneously) as energy selector and counters for neutrons in the eV energy region. Several years of extensive development have made eV neutron spectrometers operating in the so-called resonance detector spectrometer (RDS) configuration outperform their conventional counterparts. In fact, the VESUVIO spectrometer, a flagship instrument at ISIS serving a continuous user programme for eV inelastic neutron spectroscopy measurements, is operating in the RDS configuration since 2007. In this review, we discuss the physical mechanism underlying the RDS configuration and the development of associated instrumentation. A few successful neutron scattering experiments that utilize the radiative capture counting techniques will be presented together with the potential of this technique for thermal neutron diffraction measurements. We also outline possible improvements and future perspectives for radiative capture based neutron detectors in neutron scattering application at pulsed neutron sources. PMID:27502571

  4. Evaluation of Effective Delayed Neutron Fraction of RTP using MCNP

    Energy Technology Data Exchange (ETDEWEB)

    Rabir, M. H.; Hah, C. J. [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

    2013-05-15

    The prompt perturbation method needs huge computation time. Nevertheless this is not an important issue as the typical MNCP computation time is decreasing rapidly with the development of high speed computer system. The purpose of this paper is to systematically evaluate β{sub eff} for annular 1000 kW RTP TRIGA Mark II cores (Core-0 and Core-14) with different type of fuel loading, using MCNP code. The difference of β{sub eff} is 0.00019 for Core-0, 0.00009 for Core-14. The results shown in this paper are better than other papers results. In reference, β{sub eff} difference is 0.00080 for 250kW TRIGA Mark II in Ljubljana. In reference, the difference is 0.0007 for VR-1 training reactor in Prague using the same prompt perturbation method. Major part of error in prompt perturbation method originates from the exclusion of prompt neutron generated by delayed neutron. The second term in the parenthesis in equation accounts for prompt neutron source induced by delayed neutron and is always negative. Exact form of equation still has error resulting from the second order terms of the perturbation theory that should be included for exactness.

  5. Neutron dosimetry; Dosimetria de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Fratin, Luciano

    1993-12-31

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

  6. Average resonance parameters of zirconium and molybdenum nuclei

    International Nuclear Information System (INIS)

    Full sets of average resonance parameters S0, S1, R0', R1', S1,3/2 for zirconium and molybdenum nuclei with natural mixture of isotopes are determined by means of the method designed by authors. The determination is realized from analysis of the average experimental differential cross sections of neutron elastic scattering in the field of energy before 440 keV. Analysis of recommended parameters and some of the literary data had been performed also.

  7. Average resonance parameters of ruthenium and palladium nuclei

    International Nuclear Information System (INIS)

    Full sets of the average resonance parameters S0, S1, R0', R1', S1,3/2 for ruthenium and palladium nuclei with natural mixture of isotopes are determined by means of the method designed by authors. The determination is realized from analysis of the average experimental differential cross sections of neutron elastic scattering in the field of energy before 440 keV. The analysis of recommended parameters and of some of the literary data had been performed also.

  8. Prompt gamma tests of LaBr{sub 3}:Ce and BGO detectors for detection of hydrogen, carbon and oxygen in bulk samples

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A., E-mail: aanaqvi@kfupm.edu.sa [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Al-Matouq, Fares A.; Khiari, F.Z. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Isab, A.A. [Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Rehman, Khateeb-ur; Raashid, M. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)

    2012-08-21

    Prompt gamma ray tests of cylindrical lanthanum halide (LaBr{sub 3}:Ce) and bismuth germanate (BGO) gamma ray detectors have been carried out for detection of hydrogen, carbon and oxygen concentrations in bulk samples via inelastic scattering of neutrons using a 14 MeV neutron-based prompt gamma neutron activation analysis setup. Regardless of its intrinsic activity, the LaBr{sub 3}:Ce detector showed superior performance than the BGO detector for the detection of hydrogen, carbon and oxygen concentrations in benzene, water, toluene, propanol, ethanol and methanol bulk samples. The BGO detector has a large concentration of oxygen in its detector material and is consequently less sensitive for oxygen detection in bulk samples. Hence, it is not a suitable choice for oxygen determination in bulk samples.

  9. Coupled neutron and photon cross sections for transport calculations

    International Nuclear Information System (INIS)

    A compact set of multigroup cross sections and transfer tables for use in neutron and photon transport calculations was prepared from ENDF/B-IV using the NJOY processing system. The library includes prompt and steady-state coupled sets for neutrons and photons in FIDO format, prompt and steady-state fission spectra (chi vectors) for the fissionable isotopes, and a table of useful response functions including heating and gas production. These multigroup constants should be useful for a wide variety of problems where self-shielding is not important. 15 references

  10. Neutron tubes

    Science.gov (United States)

    Leung, Ka-Ngo; Lou, Tak Pui; Reijonen, Jani

    2008-03-11

    A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

  11. 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)

  12. On formation of the asymptotic spectrum of delayed neutron emitters in measuring the VVER-1000 scram system effectiveness

    Science.gov (United States)

    Shishkov, L. K.; Zizin, M. N.

    2014-12-01

    The process of formation of an asymptotic distribution of the neutron flux density in the reactor systems after introducing different negative reactivities is considered. The impact of two factors after the reactivity introduction is evaluated: (1) nonuniformity of perturbation of core properties, on one hand, and (2) a sharp reduction in the density of prompt neutrons, which prevents the appearance of new delayed neutron emitters distributed in accordance with the "new" prompt neutron distribution, on the other hand. The results of calculations show that the errors of measuring the scram system effectiveness using the method of inverse solution of the kinetics equation are caused by the fact that, after the negative reactivity insertion, the sources of prompt and delayed neutrons have different spatial distributions. In the case of high negative reactivities, this difference remains while the system still has neutrons, which can be measured.

  13. The influence of a verbal prompt on school lunch fruit consumption: a pilot study

    Directory of Open Access Journals (Sweden)

    Schwartz Marlene B

    2007-03-01

    Full Text Available Abstract Background: This study evaluated an environmental intervention intended to increase consumption of the fruit serving among elementary school children participating in the National School Lunch Program (NSLP. Methods: Children's fruit consumption was measured in two schools by observation. In the intervention school, cafeteria workers provided the verbal prompt, "Would you like fruit or juice with your lunch?" as the children stood in line in front of the fruit serving options. The control school had the same fruit and 100% juice options available, but the cafeteria workers did not provide a verbal prompt to take a fruit serving. Two variables were assessed: (1 Did children leave the lunch line with a fruit serving on their trays? and (2 Did they subsequently eat the fruit serving? Results: The average percentage of children who took a fruit serving was 60% in the control school and 90% in the intervention school. In both schools, approximately 80% of children ate the fruit on their tray. As a result, nearly 70% of the children in the intervention school consumed a fruit serving at lunch, while fewer than 40% did so in the control school. Conclusion: A simple verbal prompt appears to have a significant impact on the likelihood that children will take, and subsequently consume, a fruit serving as part of their purchased school lunch. If these findings are replicated, policymakers may consider adding verbal prompts to the serving policy of the NSLP in an effort to increase fruit consumption among school children.

  14. Neutronic Characterization of the Megapie Target

    CERN Document Server

    Panebianco, Stefano; Bokov, Pavel; Chabod, Sebastien; Chartier, Frederic; Dupont, Emmeric; Dore, Diane; Ledoux, Xavier; Letourneau, Alain; Oriol, Ludovic; Prevost, Aurelien; Ridikas, Danas; Toussaint, Jean-Christian

    2007-01-01

    The MEGAPIE project is one of the key experiments towards the feasibility of Accelerator Driven Systems. On-line operation and post-irradiation analysis will provide the scientific community with unique data on the behavior of a liquid spallation target under realistic irradiation conditions. A good neutronics performance of such a target is of primary importance towards an intense neutron source, where an extended liquid metal loop requires some dedicated verifications related to the delayed neutron activity of the irradiated PbBi. In this paper we report on the experimental characterization of the MEGAPIE neutronics in terms of the prompt neutron (PN) flux inside the target and the delayed neutron (DN) flux on the top of it. For the PN measurements, a complex detector, made of 8 microscopic fission chambers, has been built and installed in the central part of the target to measure the absolute neutron flux and its spatial distribution. Moreover, integral information on the neutron energy distribution as a f...

  15. 78 FR 39063 - Prompt Payment Interest Rate; Contract Disputes Act

    Science.gov (United States)

    2013-06-28

    ...). The Contract Disputes Act of 1978, Sec. 12, Public Law 95-563, 92 Stat. 2389, and the Prompt Payment... Fiscal Service Prompt Payment Interest Rate; Contract Disputes Act AGENCY: Bureau of the Fiscal Service... by which the interest shall be computed for interest payments under section 12 of the...

  16. 77 FR 76624 - Prompt Payment Interest Rate; Contract Disputes Act

    Science.gov (United States)

    2012-12-28

    ...). The Contract Disputes Act of 1978, Sec. 12, Public Law 95-563, 92 Stat. 2389, and the Prompt Payment... Fiscal Service Prompt Payment Interest Rate; Contract Disputes Act AGENCY: Bureau of the Public Debt... by which the interest shall be computed for interest payments under section 12 of the...

  17. 75 FR 37881 - Prompt Payment Interest Rate; Contract Disputes Act

    Science.gov (United States)

    2010-06-30

    ...). The Contract Disputes Act of 1978, Sec. 12, Public Law 95-563, 92 Stat. 2389, and the Prompt Payment... Fiscal Service Prompt Payment Interest Rate; Contract Disputes Act AGENCY: Bureau of the Public Debt... rate by which the interest shall be computed for interest payments under section 12 of the...

  18. 76 FR 38742 - Prompt Payment Interest Rate; Contract Disputes Act

    Science.gov (United States)

    2011-07-01

    ... interest penalty. 31 U.S.C. 3902(a). The Contract Disputes Act of 1978, Sec. 12, Public Law 95-563, 92 Stat... Fiscal Service Prompt Payment Interest Rate; Contract Disputes Act AGENCY: Bureau of the Public Debt... under section 12 of the Contract Disputes Act of 1978 and under the Prompt Payment Act. Under the...

  19. 76 FR 82350 - Prompt Payment Interest Rate; Contract Disputes Act

    Science.gov (United States)

    2011-12-30

    ...). The Contract Disputes Act of 1978, Sec. 12, Public Law 95-563, 92 Stat. 2389, and the Prompt Payment... Fiscal Service Prompt Payment Interest Rate; Contract Disputes Act AGENCY: Bureau of the Public Debt... rate by which the interest shall be computed for interest payments under Sec. 12 of the...

  20. An Evaluation of Response Prompts for Teaching Behavior Chains

    Science.gov (United States)

    Seaver, Jessica L.; Bourret, Jason C.

    2014-01-01

    Individuals who have been diagnosed with autism spectrum disorders can have difficulty acquiring new skills, and teaching procedures found to be efficient with 1 individual may not be efficient with others. However, relatively little research has evaluated methods to identify efficient, individualized response-prompt and prompt-fading procedures.…

  1. Simultaneous Prompting: An Instructional Strategy for Skill Acquisition

    Science.gov (United States)

    Waugh, Rebecca E.; Alberto, Paul A.; Fredrick, Laura D.

    2011-01-01

    Errorless learning is an instructional approach designed to eliminate and/or reduce the number of errors students produce in traditional trial-and-error approaches (Mueller, Palkovic, & Maynard, 2007). Various response prompting strategies are employed to produce errorless learning. Simultaneous prompting is an errorless learning strategy that has…

  2. A Flipped Spoon and Chin Prompt to Increase Mouth Clean

    Science.gov (United States)

    Dempsey, Jack; Piazza, Cathleen C.; Groff, Rebecca A.; Kozisek, Jennifer M.

    2011-01-01

    We treated the liquid refusal of a 15-month-old girl using 2 antecedent manipulations: flipped spoon and chin prompt. Use of the chin prompt in the absence of the flipped spoon failed to produce increases in mouth clean (a product measure of swallowing). By contrast, modest increases in mouth clean resulted from the implementation of the flipped…

  3. 78 FR 19690 - Submission for OMB Review; Prompt Payment

    Science.gov (United States)

    2013-04-02

    ... payment. A notice was published in the Federal Register at 78 FR 5450, on January 25, 2013. No comments...; Prompt Payment AGENCY: Department of Defense (DOD), General Services Administration (GSA), and National... by Information Collection 9000- 0102, Prompt Payment, by any of the following methods:...

  4. Status of measurements of fission neutron spectra of Minor Actinides

    Energy Technology Data Exchange (ETDEWEB)

    Drapchinsky, L.; Shiryaev, B. [V.G. Khlopin Radium Inst., Saint Petersburg (Russian Federation)

    1997-03-01

    The report considers experimental and theoretical works on studying the energy spectra of prompt neutrons emitted in spontaneous fission and neutron induced fission of Minor Actinides. It is noted that neutron spectra investigations were done for only a small number of such nuclei, most measurements, except those of Cf-252, having been carried out long ago by obsolete methods and imperfectapparatus. The works have no detailed description of experiments, analysis of errors, detailed numerical information about results of experiments. A conclusion is made that the available data do not come up to modern requirements. It is necessary to make new measurements of fission prompt neutron spectra of transuranium nuclides important for the objectives of working out a conception of minor actinides transmutation by means of special reactors. (author)

  5. Nodal model for calculating the variations in neutron flux density due to stochastic vibrations of control elements of hexagonal cross section

    International Nuclear Information System (INIS)

    Based on a three-dimensional modal geometry model for the WWER 440 reacotr, with nodes in the hexagonal z geometry, the equations for the interative calculation of the mean neutron flux density in a node and their variations due to stochastic control element vibration are shown. For modelling sources of noise, two different geometric and neutron-physics equations are used, according to the design of a control element as a spatial double pendulum with the absorber and fuel part. The neutron flux noise caused by vibration of the fuel parts is due to area sources. These are induced by material parameter variation due to control element displacement within the guide duct. The model of the 'thermal black body' absorbing hollow cylinder is transferred to bodies of hexagonal crossection for the absorber part. Both sources of noise are described as disturbances for the partial neutron current densities averaged over the node surfaces in the two group diffusion approximation. The transfer of the noise signals is dealt with in the prompt response approximation. The 'two group swelling nodes' are coupled to the 'one group transmission nodes' on the basis of the modified one group diffusion approximation. The algorithms shown are the basis for development of a computer program for examining the transfer functions depending on location of neutron flux density variations with stochastic control element vibrations as the source of noise. (orig./HP)

  6. Neutron radiography

    International Nuclear Information System (INIS)

    This introduction is addressed to an audience active in diverse forms of neutron source applications but not directly familiar with neutron radiography. Neutron radiography is, of course, similar to, and complementary to, radiography using x-rays. However, neutrons, being sensitive to the nuclear properties of materials, provide information fundamentally different from x-rays. For example, neutrons can penetrate many dense metals such as uranium, lead, bismuth or steel, and can reveal details of internal hydrogenous components: explosives, lubricants and gaskets. For nuclear fuel inspection neutron radiography offers the ability to penetrate dense uranium-238 and contrast the isotopes U-235 or Pu-239 and also offers the ability to discriminate against unwanted interference from gamma radiation. In addition to advantages in industrial applications, there are special situations in fields such as medical diagnostics, dentistry, agriculture and forensic science. Comprehensive accounts of applications in the field can be found in the proceedings of the world conferences on neutron radiography: USA (1981), FRANCE (1986). A third conference in this series is scheduled for May 1989 in Japan

  7. Neutron radiography

    International Nuclear Information System (INIS)

    The digital processing of the neutron radiography images gives the possibility for data quantification. In this case an exact relation between the measured neutron attenuation and the real macroscopic attenuation coefficient for every point of the sample is required. The assumption that the attenuation of the neutron beam through the sample is exponential is valid only in an ideal case where a monochromatic beam, non scattering sample and non background contribution are assumed. In the real case these conditions are not fulfilled and in dependence on the sample material we have more or less deviation from the exponential attenuation law. Because of the high scattering cross-sections of hydrogen (σs=80.26 barn) for thermal neutrons, the problem with the scattered neutrons at quantitative radiography investigations of hydrogenous materials (as PE, Oil, H2O, etc) is not trivial. For these strong scattering materials the neutron beam attenuation is no longer exponential and a dependence of the macroscopic attenuation coefficient on the material thickness and on the distance between the sample and the detector appears. When quantitative radiography (2 D) or tomography investigations (3 D) are performed, some image correction procedures for a description of the scattering effect are required. This thesis presents a method that can be used to enhance the neutron radiography image for objects with high scattering materials like hydrogen, carbon and other light materials. This method uses the Monte Carlo code, MCNP5, to simulate the neutron radiography process and get the flux distribution for each pixel of the image and determine the scattered neutrons distribution that causes the image blur and then subtract it from the initial image to improve its quality.

  8. Average Convexity in Communication Situations

    NARCIS (Netherlands)

    Slikker, M.

    1998-01-01

    In this paper we study inheritance properties of average convexity in communication situations. We show that the underlying graph ensures that the graphrestricted game originating from an average convex game is average convex if and only if every subgraph associated with a component of the underlyin

  9. Neutron tomography

    International Nuclear Information System (INIS)

    In this paper a survey is given of recent developments in selected areas of neutron tomography, within the context of several applications Argonne is involved in, including high penetration of reactor-fuel bundles in thick containers (involving TREAT and NRAD facilities), dual-energy hydrogen imaging (performed at IPNS), dynamic coarse-resolution emission tomography of rector fuel under test (a proposed modification to the TREAT hodoscope), and an associated-particle system that uses neutron flight-time to electronically collimate transmitted neutrons and to tomographically image nuclides identified by reaction gamma-rays

  10. Enhancing the Detector for Advanced Neutron Capture Experiments

    OpenAIRE

    Couture A.; Mosby S.; Baramsai B.; Bredeweg T. A.; Jandel M.; Macon K.; O’Donnell J.M.; Rusev G.; Taddeucci T. N; Ullmann J.L.; Walker C.L.

    2015-01-01

    The Detector for Advanced Neutron Capture Experiments (DANCE) has been used for extensive studies of neutron capture, gamma decay, photon strength functions, and prompt and delayed fission-gamma emission. Despite these successes, the potential measurements have been limited by the data acquisition hardware. We report on a major upgrade of the DANCE data acquisition that simultaneously enables strait-forward coupling to auxiliary detectors, including high-resolution high-purity germanium detec...

  11. Background by neutron activation in GERDA

    International Nuclear Information System (INIS)

    The observation of the neutrinoless double beta decay is a proof of the Majorana nature of the neutrino. The long half-life of this decay requires experiments of very low background rates in the region of interest at Qββ. Prompt γ-rays after neutron capture on germanium and the β-decay of 77Ge contribute to the background in experiments using 76Ge for the search of the neutrinoless double beta decay. The poorly known prompt γ-ray spectra and the neutron capture cross sections for the (n,γ) reactions of 74Ge and 76Ge were measured at the research reactor FRM II (Munich). The obtained data are needed in MC simulations for qualitative and quantitative background prediction in the Gerda experiment. The data and their implication on the background in Gerda are presented.

  12. Background by neutron activation in GERDA

    Energy Technology Data Exchange (ETDEWEB)

    Meierhofer, Georg; Dietrich, Dennis; Freund, Kai; Grabmayr, Peter; Hegai, Alexander; Jochum, Josef; Knapp, Markus; Ritter, Florian [Kepler Center for Astro and Particle Physics, Universitaet Tuebingen (Germany); Canella, Lea [Institut fuer Radiochemie, Technische Universitaet Muenchen (Germany); Jolie, Jan [Institut fuer Kernphysik, Universitaet zu Koeln (Germany); Kudejova, Petra [FRM II, Technische Universitaet Muenchen (Germany)

    2010-07-01

    The observation of the neutrinoless double beta decay is a proof of the Majorana nature of the neutrino. The long half-life of this decay requires experiments of very low background rates in the region of interest at Q{sub {beta}}{sub {beta}}. Prompt {gamma}-rays after neutron capture on germanium and the {beta}-decay of {sup 77}Ge contribute to the background in experiments using {sup 76}Ge for the search of the neutrinoless double beta decay. The poorly known prompt {gamma}-ray spectra and the neutron capture cross sections for the (n,{gamma}) reactions of {sup 74}Ge and {sup 76}Ge were measured at the research reactor FRM II (Munich). The obtained data are needed in MC simulations for qualitative and quantitative background prediction in the Gerda experiment. The data and their implication on the background in Gerda are presented.

  13. Incoherent neutron-scattering determination of hydrogen content: Theory and modeling

    NARCIS (Netherlands)

    Perego, R.C.; Blaauw, M.

    2005-01-01

    Hydrogen concentrations of 0 up to 350 mg/kg in a titanium alloy have been determined at National Institute of Standards and Technology (NIST) with neutron incoherent scattering (NIS) and with cold neutron prompt gamma activation analysis. The latter is a well-established technique, while the former

  14. Neutron radiography in the plasma focus

    International Nuclear Information System (INIS)

    Starting with some theoretical considerations, the paper describes the experimental basis for neutron radiography in the plasma focus. With an appropriate combination of scintillator and image converter, average optical density can already be reached at neutron density of about 5 x 104 n/cm2. Contrast studies near the plasma focus with the aid of neutrons have thus become possible for the first time. (author)

  15. Neutron Based Imaging and Element-mapping at the Budapest Neutron Centre

    Science.gov (United States)

    Kis, Z.; Szentmiklósi, L.; Belgya, T.; Balaskó, M.; Horváth, L. Z.; Maróti, B.

    The Budapest Neutron Centre (BNC) is a consortium of institutes to co-ordinate research activities carried out at the Budapest Research Reactor. It hosts two neutron imaging facilities (RAD and NORMA) operated by the Centre for Energy Research, Hungarian Academy of Sciences and offers access to this scientific infrastructure for the domestic and international users. The radiography station (RAD) at the thermal neutron beamline of the reactor gives a possibility to study relatively large objects by thermal neutron-, gamma- and X-ray radiography, and to benefit from the complementary features of the different radiations. RAD is being extended in 2014 with digital imaging and tomographic capabilities. The image detection is based on suitable converter screens. The static radiography and tomography images are acquired by a new, large area sCMOS camera, whereas the dynamic radiography is accomplished by a low-light-level TV camera and a frame grabber card. The NORMA facility is designed to perform neutron radiography and tomography on small samples using guided cold neutrons. Here two non-destructive techniques are coupled to determine the chemical composition and to visualize the internal structure of heterogeneous objects. The position-sensitive element analysis with prompt-gamma activation analysis (PGAA) and the imaging with neutron radiography/tomography (NR/NT) are integrated into a unique facility called NIPS-NORMA. The goal of such a combination of these methods is to save substantial beam time in the so-called NR/NT-driven PGAI (Prompt Gamma Activation Imaging) mode, in which the interesting regions are first visualized and located, and subsequently the time-consuming prompt-gamma measurements are made only where it is really needed. The paper will give an overview about the technical details of the facilities, and the latest results of selected applications from the fields of archaeometry, engineering and material science.

  16. DPZ-1M rhodium neutron detector performance

    International Nuclear Information System (INIS)

    The characteristics of the DPZ-1M rhodium self-powered neutron detector based on the calculational technique using corrected experimental data are given. These detectors are used for power distribution monitoring in the WWER reactors. For calculating neutron absorption in an emitter incident neutron flux is specified, while the probability of β-particles escape is determined on the base of empirical dependence of extrapolated electron path on its energy. In addition correction by the emither radius of the probability distribution of β-particles escape by experimental data is performed. The results obtained permit to conclude that the rhodium detector possesses high sensitivity to epithermal neutrons Which depends on the neutron spectrum form; current relation of burned-up and non burned- up detector seightly depends on the spectrum form, neutron gas temperature and average neutron spectral hardness

  17. The difference between alternative averages

    Directory of Open Access Journals (Sweden)

    James Vaupel

    2012-09-01

    Full Text Available BACKGROUND Demographers have long been interested in how compositional change, e.g., change in age structure, affects population averages. OBJECTIVE We want to deepen understanding of how compositional change affects population averages. RESULTS The difference between two averages of a variable, calculated using alternative weighting functions, equals the covariance between the variable and the ratio of the weighting functions, divided by the average of the ratio. We compare weighted and unweighted averages and also provide examples of use of the relationship in analyses of fertility and mortality. COMMENTS Other uses of covariances in formal demography are worth exploring.

  18. Probing energy dissipation, γ-ray and neutron multiplicity in the thermal neutron-induced fission of 239Pu

    Science.gov (United States)

    Pahlavani, M. R.; Mirfathi, S. M.

    2016-04-01

    The incorporation of the four-dimensional Langevin equations led to an integrative description of fission cross-section, fragment mass distribution and the multiplicity and energy distribution of prompt neutrons and γ-rays in the thermal neutron-induced fission of 239Pu. The dynamical approach presented in this paper thoroughly reproduces several experimental observables of the fission process at low excitation energy.

  19. Probing energy dissipation, γ-ray and neutron multiplicity in the thermal neutron-induced fission of {sup 239}Pu

    Energy Technology Data Exchange (ETDEWEB)

    Pahlavani, M.R.; Mirfathi, S.M. [University of Mazandaran, Department of Nuclear Physics, Faculty of Basic Science, Babolsar (Iran, Islamic Republic of)

    2016-04-15

    The incorporation of the four-dimensional Langevin equations led to an integrative description of fission cross-section, fragment mass distribution and the multiplicity and energy distribution of prompt neutrons and γ-rays in the thermal neutron-induced fission of {sup 239}Pu. The dynamical approach presented in this paper thoroughly reproduces several experimental observables of the fission process at low excitation energy. (orig.)

  20. Progress report on neutron science. April 1, 2006 - March 31, 2007

    International Nuclear Information System (INIS)

    There are 13 research groups in neutron science and technology in the Quantum Beam Science Directorate (QuBS) and Advanced Science Research Center (ASRC) of Japan Atomic Research Agency (JAEA). A wide variety of research is performed by these group: neutron scattering (condensed matter physics, polymer science, biology, and residual stress analysis), prompt gamma-ray analysis, neutron radiography, neutron optics, and development of a neutron spectrometer, neutron beam handling device and neutron detector. This issue summarizes research progress in neutron science and technology including activities of the Nuclear Science and Engineering Directorate of JAEA, and of the COMMON USE PROGRAM of JAEA utilizing the research reactor JRR-3 during the period between April 1, 2006 and March 31, 2007. This report contains highlights of research by these 13 neutron research groups of QuBS and ASRC, introducing 68 experimental reports. (author)

  1. Neutron scattering

    International Nuclear Information System (INIS)

    This report contains the text of 16 lectures given at the Summer School and the report on a panel discussion entitled ''the relative merits and complementarities of x-rays, synchrotron radiation, steady- and pulsed neutron sources''. figs., tabs., refs

  2. Neutron multiplicities for the transplutonium nuclides

    International Nuclear Information System (INIS)

    This paper continues, with respect to the transplutonium nuclides, earlier efforts to collate and evaluate data from the scientific literature on the prompt neutron multiplicity distribution from fission and its first moment = ΣnuPnu. The isotopes considered here for which P/sub nu/ and or data (or both) were found in the literature are of americium (Am), curium (Cm), berkelium (Bk), californium (Cf), einsteinium (Es), fermium (Fm), and nobelium (No)

  3. Piezonuclear Neutrons

    CERN Document Server

    Cardone, Fabio; Petrucci, Andrea

    2008-01-01

    We report the results of neutron measurements carried out during the application of ultrasounds to a solution containing only stable elements like Iron and Chlorine, without any other radioactive source of any kind. These measurements, carried out by CR39 detectors and a Boron TriFouride electronic detector, evidenced the emission of neutron pulses. These pulses stand well above the electronic noise and the background of the laboratory where the measurements were carried out.

  4. Subphotospheric neutrinos from gamma-ray bursts: the role of neutrons.

    Science.gov (United States)

    Murase, Kohta; Kashiyama, Kazumi; Mészáros, Peter

    2013-09-27

    Relativistic outflows with neutrons inevitably lead to inelastic collisions, and resulting subphotospheric γ rays may explain prompt emission of γ-ray bursts. In this model, hadronuclear, quasithermal neutrinos in the 10-100 GeV range should be generated, and they may even have a high-energy tail by neutron-proton-converter or shock acceleration mechanisms. We demonstrate the importance of dedicated searches with DeepCore+IceCube, though such analyses have not been performed. Successful detections enable us to discriminate among prompt emission mechanisms, probe the jet composition, and see roles of relativistic neutrons as well as effects of cosmic-ray acceleration. PMID:24116764

  5. Process and device for substance detection in particular explosives by neutron irradiation

    International Nuclear Information System (INIS)

    At a first check point the object is irradiated by thermal neutrons. Capture gamma radiation eventually emitted and characteristic of a chemical element is detected, if the radiation intensity is over a predetermined threshold the object is irradiated by fast neutrons at a second check point and prompt gamma radiation is eventually detected and is characteristic of the chemical element, fast neutron energy is at least equal to prompt gamma energy for confirmation or not of information obtained at the first check point. Application to luggage checking in air ports

  6. Measurements of prompt radiation induced conductivity of Kapton.

    Energy Technology Data Exchange (ETDEWEB)

    Preston, Eric F. (ITT Corporation, Colorado Springs, CO); Zarick, Thomas Andrew; Sheridan, Timothy J.; Hartman, E. Frederick; Stringer, Thomas Arthur (ITT Corporation, Colorado Springs, CO)

    2010-10-01

    We performed measurements of the prompt radiation induced conductivity in thin samples of Kapton (polyimide) at the Little Mountain Medusa LINAC facility in Ogden, UT. Three mil samples were irradiated with a 0.5 {mu}s pulse of 20 MeV electrons, yielding dose rates of 1E9 to 1E10 rad/s. We applied variable potentials up to 2 kV across the samples and measured the prompt conduction current. Analysis rendered prompt conductivity coefficients between 6E-17 and 2E-16 mhos/m per rad/s, depending on the dose rate and the pulse width.

  7. Monitoring the Bragg peak location of 73 MeV/u carbon ions by means of prompt $\\gamma$-ray measurements

    OpenAIRE

    Testa, E; Bajard, M.; Chevallier, M.; Dauvergne, D.; Le Foulher, F.; Poizat, J.-C.; Ray, C.; Testa, M.; Freud, N.; Létang, J.-M.

    2008-01-01

    to be published in Applied Physics Letters By means of a time-of-flight technique, we measured the longitudinal profile of prompt $\\gamma$-rays emitted by 73 MeV/u $^{13}$C ions irradiating a PMMA target. This technique allowed us to minimize the shielding against neutrons and scattered $\\gamma$-rays, and to correlate prompt gamma emission to the ion path. This correlation, together with a high counting rate, paves the way toward real-time monitoring of the longitudinal dose profile during...

  8. FOREWORD: Neutron metrology Neutron metrology

    Science.gov (United States)

    Thomas, David J.; Nolte, Ralf; Gressier, Vincent

    2011-12-01

    The International Committee for Weights and Measures (CIPM) has consultative committees covering various areas of metrology. The Consultative Committee for Ionizing Radiation (CCRI) differs from the others in having three sections: Section (I) deals with radiation dosimetry, Section (II) with radionuclide metrology and Section (III) with neutron metrology. In 2003 a proposal was made to publish special issues of Metrologia covering the work of the three Sections. Section (II) was the first to complete their task, and their special issue was published in 2007, volume 44(4). This was followed in 2009 by the special issue on radiation dosimetry, volume 46(2). The present issue, volume 48(6), completes the trilogy and attempts to explain neutron metrology, the youngest of the three disciplines, the neutron only having been discovered in 1932, to a wider audience and to highlight the relevance and importance of this field. When originally approached with the idea of this special issue, Section (III) immediately saw the value of a publication specifically on neutron metrology. It is a topic area where papers tend to be scattered throughout the literature in journals covering, for example, nuclear instrumentation, radiation protection or radiation measurements in general. Review articles tend to be few. People new to the field often ask for an introduction to the various topics. There are some excellent older textbooks, but these are now becoming obsolete. More experienced workers in specific areas of neutron metrology can find it difficult to know the latest position in related areas. The papers in this issue attempt, without presenting a purely historical outline, to describe the field in a sufficiently logical way to provide the novice with a clear introduction, while being sufficiently up-to-date to provide the more experienced reader with the latest scientific developments in the different topic areas. Neutron radiation fields obviously occur throughout the nuclear

  9. Neutron kinetics in moderators and SNM detection through epithermal-neutron-induced fissions

    Science.gov (United States)

    Gozani, Tsahi; King, Michael J.

    2016-01-01

    Extension of the well-established Differential Die Away Analysis (DDAA) into a faster time domain, where more penetrating epithermal neutrons induce fissions, is proposed and demonstrated via simulations and experiments. In the proposed method the fissions stimulated by thermal, epithermal and even higher-energy neutrons are measured after injection of a narrow pulse of high-energy 14 MeV (d,T) or 2.5 MeV (d,D) source neutrons, appropriately moderated. The ability to measure these fissions stems from the inherent correlation of neutron energy and time ("E-T" correlation) during the process of slowing down of high-energy source neutrons in common moderating materials such as hydrogenous compounds (e.g., polyethylene), heavy water, beryllium and graphite. The kinetic behavior following injection of a delta-function-shaped pulse (in time) of 14 MeV neutrons into such moderators is studied employing MCNPX simulations and, when applicable, some simple "one-group" models. These calculations served as a guide for the design of a source moderator which was used in experiments. Qualitative relationships between slowing-down time after the pulse and the prevailing neutron energy are discussed. A laboratory system consisting of a 14 MeV neutron generator, a polyethylene-reflected Be moderator, a liquid scintillator with pulse-shape discrimination (PSD) and a two-parameter E-T data acquisition system was set up to measure prompt neutron and delayed gamma-ray fission signatures in a 19.5% enriched LEU sample. The measured time behavior of thermal and epithermal neutron fission signals agreed well with the detailed simulations. The laboratory system can readily be redesigned and deployed as a mobile inspection system for SNM in, e.g., cars and vans. A strong pulsed neutron generator with narrow pulse (<75 ns) at a reasonably high pulse frequency could make the high-energy neutron induced fission modality a realizable SNM detection technique.

  10. Physical Theories with Average Symmetry

    CERN Document Server

    Alamino, Roberto C

    2013-01-01

    This Letter probes the existence of physical laws invariant only in average when subjected to some transformation. The concept of a symmetry transformation is broadened to include corruption by random noise and average symmetry is introduced by considering functions which are invariant only in average under these transformations. It is then shown that actions with average symmetry obey a modified version of Noether's Theorem with dissipative currents. The relation of this with possible violations of physical symmetries, as for instance Lorentz invariance in some quantum gravity theories, is briefly commented.

  11. Gadolinium as a Neutron Capture Therapy Agent

    Science.gov (United States)

    Shih, Jing-Luen Allen

    The clinical results of treating brain tumors with boron neutron capture therapy are very encouraging and researchers around the world are once again making efforts to develop this therapeutic modality. Boron-10 is the agent receiving the most attention for neutron capture therapy but ^{157}Gd is a nuclide that also holds interesting properties of being a neutron capture therapy agent. The objective of this study is to evaluate ^{157}Gd as a neutron capture therapy agent. In this study it is determined that tumor concentrations of about 300 mug ^{157}Gd/g tumor can be achieved in brain tumors with some FDA approved MRI contrast agents such as Gd-DTPA and Gd-DOTA, and up to 628 mug ^{157 }Gd/g tumor can be established in bone tumors with Gd-EDTMP. Monte Carlo calculations show that with only 250 ppm of ^{157}Gd in tumor, neutron capture therapy can deliver 2,000 cGy to a tumor of 2 cm diameter or larger with 5 times 10^{12} n/cm ^2 fluence at the tumor. Dose measurements which were made with films and TLD's in phantoms verified these calculations. More extended Monte Carlo calculations demonstrate that neutron capture therapy with Gd possesses comparable dose distribution to B neutron capture therapy. With 5 times 10^{12 } n/cm^2 thermal neutrons at the tumor, Auger electrons from the Gd produced an optical density enhancement on the films that is similar to the effect caused by about 300 cGy of Gd prompt gamma dose which will further enhance the therapeutic effects. A technique that combines brachytherapy with Gd neutron capture therapy has been evaluated. Monte Carlo calculations show that 5,000 cGy of prompt gamma dose can be delivered to a treatment volume of 40 cm^3 with a 3-plane implant of a total of 9 Gd needles. The tumor to normal tissue advantage of this method is as good as ^{60} Co brachytherapy. Measurements of prompt gamma dose with films and TLD-700's in a lucite phantom verify the Monte Carlo evaluation. A technique which displays the Gd

  12. Monitoring of D-T accelerator neutron output in a PGNAA system using silicon carbide detectors

    International Nuclear Information System (INIS)

    Silicon carbide (SiC) detectors are being employed to monitor the neutron output of the D-T accelerator in a pulsed Prompt Gamma Neutron Activation Analysis (PGNAA) system. Detection of the source neutrons relies on energetic neutron reactions in the detector material. Experimental testing has been performed to confirm that the detector response is caused by fast neutrons from the accelerator source. Modeling calculations have also been carried out to provide additional verification. Use of the SiC detectors in the PGNAA system is expected to assist in evaluating system performance as well as ensuring accurate data interpretation and analysis

  13. Monitoring of D-T accelerator neutron output in a PGNAA system using silicon carbide detectors

    Science.gov (United States)

    Dulloo, Abdul R.; Ruddy, Frank H.; Seidel, John G.; Petrović, Bojan

    2001-07-01

    Silicon carbide (SiC) detectors are being employed to monitor the neutron output of the D-T accelerator in a pulsed Prompt Gamma Neutron Activation Analysis (PGNAA) system. Detection of the source neutrons relies on energetic neutron reactions in the detector material. Experimental testing has been performed to confirm that the detector response is caused by fast neutrons from the accelerator source. Modeling calculations have also been carried out to provide additional verification. Use of the SiC detectors in the PGNAA system is expected to assist in evaluating system performance as well as ensuring accurate data interpretation and analysis.

  14. Maxwellian-averaged Cross Section Calculated From CENDL-3.0

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    For the propose of using in astrophysics the Maxwellian-averaged cross sections of neutron capture,fission, (n, p) and (n, α) reactions are calculated from the CENDL-3.0, and the temperature (kT)from 1

  15. Recent Work Leading Towards a New Evaluation of the Neutron Standards

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, A.D., E-mail: carlson@nist.gov [National Institute of Standards and Technology, 100 Bureau Drive STOP 8463, Gaithersburg, MD 20899-8463 (United States); Pronyaev, V.G. [Institute of Physics and Power Engineering, Bondarenko Sq. 1, 249 033 Obninsk, Kaluga Region (Russian Federation); Capote, R. [NAPC-Nuclear Data Section, International Atomic Energy Agency, Vienna (Austria); Hale, G.M. [Los Alamos National Laboratory, Los Alamos NM, 87545 (United States); Hambsch, F.-J. [EC-JRC-IRMM, Retieseweg 111, B-2440, Geel (Belgium); Kawano, T. [Los Alamos National Laboratory, Los Alamos NM, 87545 (United States); Kunieda, S. [Japan Atomic Energy Agency, Nuclear Data Center, 2-4 Shirane, Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Mannhart, W. [Physikalisch-Technische Bundesanstalt, Org. 6.4, Bundesallee 100, 38116, Braunschweig (Germany); Nelson, R.O.; Neudecker, D. [Los Alamos National Laboratory, Los Alamos NM, 87545 (United States); Schillebeeckx, P. [EC-JRC-IRMM, Retieseweg 111, B-2440, Geel (Belgium); Simakov, S. [NAPC-Nuclear Data Section, International Atomic Energy Agency, Vienna (Austria); Smith, D.L. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439 (United States); Talou, P. [Los Alamos National Laboratory, Los Alamos NM, 87545 (United States); Tao, X. [China Institute of Atomic Energy, China Nuclear Data Center, P.O. Box 275(41), Beijing 102413 (China); Wallner, A. [Vera Laboratory, Faculty of Physics, University of Vienna, Waehringer Strasse 17, A-1090, Vienna (Austria); Dept. of Nuclear Physics, The Australian National University, Garran Road, Canberra ACT 0200 (Australia); Wang, W. [China Institute of Atomic Energy, China Nuclear Data Center, P.O. Box 275(41), Beijing 102413 (China)

    2015-01-15

    A new version of the ENDF/B library has been planned. The first step in producing this new library is evaluating the neutron standards. An evaluation is now underway with support from a Data Development Project of the IAEA. In addition to the neutron cross section standards, new evaluations are being done for prompt fission neutron spectra and a number of reference data. Efforts have been made to handle uncertainties in a proper way in these evaluations.

  16. Fostering Information Problem Solving Skills Through Completion Problems and Prompts

    NARCIS (Netherlands)

    Frerejean, Jimmy; Brand-Gruwel, Saskia; Kirschner, Paul A.

    2012-01-01

    Frerejean, J., Brand-Gruwel, S., & Kirschner, P. A. (2012, September). Fostering Information Problem Solving Skills Through Completion Problems and Prompts. Poster presented at the EARLI SIG 6 & 7 "Instructional Design" and "Learning and Instruction with Computers", Bari, Italy.

  17. Fostering information problem solving skills through completion problems and prompts

    NARCIS (Netherlands)

    Frerejean, Jimmy; Brand-Gruwel, Saskia; Kirschner, Paul A.

    2012-01-01

    Frerejean, J., Brand-Gruwel, S., & Kirschner, P. A. (2012, November). Fostering information problem solving skills through completion problems and prompts. Poster presented at the ICO Fall School 2012, Girona, Spain.

  18. Prompt Optical Detection of GRB 050401 with ROTSE-IIIa

    CERN Document Server

    Rykoff, E S; Krimm, H A; Aharonian, F; Akerlof, C W; Alatalo, K; Ashley, M C B; Barthelmy, S D; Gehrels, N; Guver, T; Horns, D; Kiziloglu, U; McKay, T A; Ozel, M; Phillips, A; Quimby, R M; Rujopakarn, W; Schaefer, B E; Smith, D A; Swan, H F; Vestrand, W T; Wheeler, J C; Wren, J

    2005-01-01

    The ROTSE-IIIa telescope at Siding Spring Observatory, Australia, detected prompt optical emission from Swift GRB 050401. In this letter, we present observations of the early optical afterglow, first detected by the ROTSE-IIIa telescope 33 s after the start of gamma-ray emission, contemporaneous with the brightest peak of this emission. This GRB was neither exceptionally long nor bright. This is the first prompt optical detection of a GRB of typical duration and luminosity. We find that the early afterglow decay does not deviate significantly from the power-law decay observable at later times, and is uncorrelated with the prompt gamma-ray emission. We compare this detection with the other two GRBs with prompt observations, GRB 990123 and GRB 041219a. All three bursts exhibit quite different behavior at early times.

  19. Measurement of Prompt Photon Cross Sections in Photoproduction at HERA

    CERN Document Server

    Andreev, V; Asmone, A; Babaev, A; Backovic, S; Bähr, J; Baranov, P; Barrelet, E; Bartel, Wulfrin; Baumgartner, S; Becker, J; Beckingham, M; Behnke, O; Behrendt, O; Belousov, A; Berger, C; Berger, N; Berndt, T; Bizot, J C; Böhme, J; Boenig, M O; Boudry, V; Bracinik, J; Brisson, V; Broker, H B; Brown, D P; Bruncko, Dusan; Büsser, F W; Bunyatyan, A; Buschhorn, G; Bystritskaya, L; Campbell, A J; Caron, S; Cassol-Brunner, F; Cerny, K; Chekelian, V; Collard, Caroline; Contreras, J G; Coppens, Y R; Coughlan, J A; Cox, B E; Cozzika, G; Cvach, J; Dainton, J B; Dau, W D; Daum, K; Delcourt, B; Demirchyan, R; de Roeck, A; Desch, Klaus; De Wolf, E A; Diaconu, C; Dingfelder, J; Dodonov, V; Dubak, A; Duprel, C; Eckerlin, G; Efremenko, V; Egli, S; Eichler, R; Eisele, F; Ellerbrock, M; Elsen, E; Erdmann, M; Erdmann, W; Faulkner, P J W; Favart, L; Fedotov, A; Felst, R; Ferencei, J; Fleischer, M; Fleischmann, P; Fleming, Y H; Flucke, G; Flügge, G; Fomenko, A; Foresti, I; Formánek, J; Franke, G; Frising, G; Gabathuler, Erwin; Gabathuler, K; Garutti, E; Garvey, J; Gayler, J; Gerhards, R; Gerlich, C; Ghazaryan, S; Görlich, L; Gogitidze, N; Gorbounov, S; Grab, C; Grässler, Herbert; Greenshaw, T; Gregori, M; Grindhammer, G; Gwilliam, C; Haidt, D; Hajduk, L; Haller, J; Hansson, M; Heinzelmann, G; Henderson, R C W; Henschel, H; Henshaw, O; Heremans, R; Herrera-Corral, G; Herynek, I; Heuer, R D; Hildebrandt, M; Hiller, K H; Hladky, J; Hoting, P; Hoffmann, D; Horisberger, R P; Hovhannisyan, A; Ibbotson, M; Ismail, M; Jacquet, M; Janauschek, L; Janssen, X; Jemanov, V; Jönsson, L B; Johnson, D P; Jung, H; Kant, D; Kapichine, M; Karlsson, M; Katzy, J; Keller, N; Kennedy, J; Kenyon, I R; Kiesling, C; Klein, M; Kleinwort, C; Kluge, T; Knies, G; Knutsson, A; Koblitz, B; Korbel, V; Kostka, P; Koutouev, R; Kropivnitskaya, A; Kroseberg, J; Kuckens, J; Kuhr, T; Landon, M P J; Lange, W; Lastoviicka, T; Laycock, P; Lebedev, A; Leiner, B; Lemrani, R; Lendermann, V; Levonian, S; Lindfeld, L; Lipka, K; List, B; Lobodzinska, E; Loktionova, N A; López-Fernandez, R; Lubimov, V; Lüders, H; Lüke, D; Lux, T; Lytkin, L; Makankine, A; Malden, N; Malinovskii, E I; Mangano, S; Marage, P; Marks, J; Marshall, R; Martisikova, M; Martyn, H U; Maxfield, S J; Meer, D; Mehta, A; Meier, K; Meyer, A B; Meyer, H; Meyer, J; Michine, S; Mikocki, S; Milcewicz-Mika, I; Milstead, D; Mohamed, A; Moreau, F; Morozov, A; Morozov, I; Morris, J V; Mozer, M U; Müller, K; Murn, P; Nagovizin, V; Naroska, Beate; Naumann, J; Naumann, T; Newman, P R; Niebuhr, C B; Nikiforov, A; Nikitin, D K; Nowak, G; Nozicka, M; Oganezov, R; Olivier, B; Olsson, J E; Ossoskov, G; Ozerov, D; Pascaud, C; Patel, G D; Peez, M; Pérez, E; Perieanu, A; Petrukhin, A; Pitzl, D; Placakyte, R; Pöschl, R; Portheault, B; Povh, B; Raicevic, N; Ratiani, Z; Reimer, P; Reisert, B; Rimmer, A; Risler, C; Rizvi, E; Robmann, P; Roland, B; Roosen, R; Rostovtsev, A A; Rurikova, Z; Rusakov, S V; Rybicki, K; Sankey, D P C; Sauvan, E; Schatzel, S; Scheins, J; Schilling, F P; Schleper, P; Schmidt, S; Schmitt, S; Schneider, M; Schoeffel, L; Schöning, A; Schröder, V; Schultz-Coulon, H C; Schwanenberger, C; Sedlak, K; Sefkow, F; Shevyakov, I; Shtarkov, L N; Sirois, Y; Sloan, T; Smirnov, P; Soloviev, Yu; South, D; Spaskov, V; Specka, A; Spitzer, H; Stamen, R; Stella, B; Stiewe, J; Strauch, I; Straumann, U; Tchoulakov, V; Thompson, G; Thompson, P D; Tomasz, F; Traynor, D; Truöl, P; Tsipolitis, G; Tsurin, I; Turnau, J; Tzamariudaki, E; Uraev, A; Urban, M; Usik, A; Utkin, D; Valkár, S; Vallée, C; Van Mechelen, P; Vargas-Trevino, A; Vazdik, Ya A; Veelken, C; Vest, A; Vinokurova, S; Volchinski, V; Wacker, K; Wagner, J; Weber, G; Weber, R; Wegener, D; Werner, C; Werner, N; Wessels, M; Wessling, B; Winter, G G; Wissing, C; Woerling, E E; Wolf, R; Wünsch, E; Xella, S M; Yan, W; Zaicek, J; Zaleisak, J; Zhang, Z; Zhokin, A; Zohrabyan, H G; Zomer, F

    2004-01-01

    Results are presented on the photoproduction of isolated prompt photons, inclusively and associated with jets, in the gamma p center of mass energy range 142 4.5 GeV. They are measured differentially as a function of E_T^gamma, E_T^jet, the pseudorapidities eta^gamma and eta^jet and estimators of the momentum fractions x_gamma and x_p of the incident photon and proton carried by the constituents participating in the hard process. In order to further investigate the underlying dynamics, the angular correlation between the prompt photon and the jet in the transverse plane is studied. Predictions by perturbative QCD calculations in next to leading order are about 30% below the inclusive prompt photon data after corrections for hadronisation and multiple interactions, but are in reasonable agreement with the results for prompt photons associated with jets. Comparisons with the predictions of the event generators PYTHIA and HERWIG are also presented.

  20. [A clinical trial of neutron capture therapy for brain tumors

    International Nuclear Information System (INIS)

    This report describes accomplishments by this laboratory concerning development of high-resolution alpha-autoradiography design of an optimized epithermal neutron beam dosimetry and treatment planning Using Monte Carlo techniques development of a prompt-gamma 10B analysis facility

  1. Non-Fick ian law for the neutron density current

    International Nuclear Information System (INIS)

    In this paper, a fractional wave equation for the average neutron motion in a nuclear reactor is considered. This representation covers the full spectrum of the average neutron transport behavior, i.e., Fick ian and non-Fick ian effects. The fractional diffusion model retains the main dynamic characteristics of the neutron motion. The relaxation time associated with a rapid variation in the neutron flux contains an adjustable parameter, which can be manipulated to obtain the best representation of the neutron transport phenomena. (Author)

  2. Isotopic yield distribution of neutron-rich fragment nuclei produced in thermal neutron induced fission

    International Nuclear Information System (INIS)

    Nuclear fission allows us to produce and study the properties of the nuclei with a higher neutron to proton ratio. Spectroscopic studies of such neutron-rich fragment nuclei provide direct information on the nuclear excited states. Such studies help to explore the new regions of nuclear deformations, and to extend the theoretical model(s) to regions which have hitherto been inaccessible. A lot of work has already been done on these set of nuclei by means of spontaneous fission of 252Cf and 248Cm sources, heavy-ion induced fusion-fission reactions, and also using deep-inelastic reactions. More recently, spectroscopic studies were performed using thermal neutron induced fission of 235U using CIRUS reactor facility. Here we report the yield distribution of the isotopes, produced in thermal neutron induced fission of 235U, using prompt γ-γ coincidence measurement technique

  3. Neutron CSI: Integrated platform for non-destructive composition and stress imaging with neutrons

    International Nuclear Information System (INIS)

    We propose to build an interdisciplinary platform for non-destructive analysis and imaging with neutrons. The project regroups an instrument already available at ILL (Laue-Langevin Institute), SALSA, with a new one for Neutron Tomography coupled to Prompt-Gamma Neutron Activation (PGNA) as well as partial usage of another proposed instrument, FIPPS. The focus of the proposition is the versatility of high spatial resolution and energy-selective neutron tomography to provide a rapid and precise 3D morphological map of an object as well as indirect information on its 3D elemental and structural composition through the scan of Bragg-edges in transmission. Coupled to PGNA imaging and the strain analysis power of SALSA, the aim of the platform is to answer key questions occurring in geological, metallurgical, engineering and medical fields, material research and cultural heritage. (authors)

  4. "Pricing Average Options on Commodities"

    OpenAIRE

    Kenichiro Shiraya; Akihiko Takahashi

    2010-01-01

    This paper proposes a new approximation formula for pricing average options on commodities under a stochastic volatility environment. In particular, it derives an option pricing formula under Heston and an extended lambda-SABR stochastic volatility models (which includes an extended SABR model as a special case). Moreover, numerical examples support the accuracy of the proposed average option pricing formula.

  5. Quantized average consensus with delay

    NARCIS (Netherlands)

    Jafarian, Matin; De Persis, Claudio

    2012-01-01

    Average consensus problem is a special case of cooperative control in which the agents of the network asymptotically converge to the average state (i.e., position) of the network by transferring information via a communication topology. One of the issues of the large scale networks is the cost of co

  6. Monte Carlo calculation of neutron generation time in critical reactor and subcritical reactor with an external source

    International Nuclear Information System (INIS)

    The neutron generation time Λ plays an important role in the reactor kinetics. However, it is not straightforward nor standard in most continuous energy Monte Carlo codes which are able to calculate the prompt neutron lifetime lp directly. The difference between Λ and lp are sometimes very apparent. As very few delayed neutrons are produced in the reactor, they have little influence on Λ. Thus on the assumption that no delayed neutrons are produced in the system, the prompt kinetics equations for critical system and subcritical system with an external source are proposed. And then the equations are applied to calculating Λ with pulsed neutron technique using Monte Carlo. Only one fission neutron source is simulated with Monte Carlo in critical system while two neutron sources, including a fission source and an external source, are simulated for subcritical system. Calculations are performed on both critical benchmarks and subcritical system with an external source and the results are consistent with the reference values. (author)

  7. Neutron capture cross section measurements for 238U in the resonance region at GELINA

    Science.gov (United States)

    Kim, H. I.; Paradela, C.; Sirakov, I.; Becker, B.; Capote, R.; Gunsing, F.; Kim, G. N.; Kopecky, S.; Lampoudis, C.; Lee, Y.-O.; Massarczyk, R.; Moens, A.; Moxon, M.; Pronyaev, V. G.; Schillebeeckx, P.; Wynants, R.

    2016-06-01

    Measurements were performed at the time-of-flight facility GELINA to determine the 238U(n, γ) cross section in the resonance region. Experiments were carried out at a 12.5 and 60m measurement station. The total energy detection principle in combination with the pulse height weighting technique was applied using C6D6 liquid scintillators as prompt γ-ray detectors. The energy dependence of the neutron flux was measured with ionisation chambers based on the 10B(n, α) reaction. The data were normalised to the isolated and saturated 238U resonance at 6.67 eV. Special procedures were applied to reduce bias effects due to the weighting function, normalization, dead time and background corrections, and corrections related to the sample properties. The total uncertainty due to the weighting function, normalization, neutron flux and sample characteristics is about 1.5%. Resonance parameters were derived from a simultaneous resonance shape analysis of the GELINA capture data and transmission data obtained previously at a 42m and 150m station of ORELA. The parameters of resonances below 500 eV are in good agreement with those resulting from an evaluation that was adopted in the main data libraries. Between 500 eV and 1200 eV a systematic difference in the neutron width is observed. Average capture cross section data were derived from the experimental capture yield in the energy region between 3.5 keV and 90 keV. The results are in good agreement with an evaluated cross section resulting from a least squares fit to experimental data available in the literature prior to this work. The average cross section data derived in this work were parameterised in terms of average resonance parameters and included in a least squares analysis together with other experimental data reported in the literature.

  8. Neutron Repulsion

    CERN Document Server

    Manuel, Oliver K

    2011-01-01

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

  9. Layered magnets: polarized neutron reflection studies

    Energy Technology Data Exchange (ETDEWEB)

    Zabel, H.; Schreyer, A. [Ruhr-Univ. Bochum, Lehrstuhl fuer Experimentalphysik/Festkoerperphysik, Bochum (Germany)

    1996-11-01

    Neutron reflectivity measurements from extended surfaces, thin films and superlattices provide information on the chemical profile parallel to the film normal, including film thicknesses, average composition and interfacial roughness parameters. Reflectivity measurements with polarized neutrons are particularly powerful for analyzing the magnetic density profiles in thin films and superlattices in addition to chemical profiles. The basic theory of polarized neutron reflectivity is provided, followed by some examples and more recent applications concerning polarized neutron reflectivity studies from exchange coupled Fe/Cr superlattices. (author) 5 figs., 13 refs.

  10. PROMPT: Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes

    CERN Document Server

    Reichart, D; Moran, J; Bartelme, J; Bayliss, M; Foster, A; Clemens, J C; Price, P; Evans, C; Salmonson, J; Trammell, S; Carney, B W; Keohane, J; Gotwals, R

    2005-01-01

    Funded by $1.2M in grants and donations, we are now building PROMPT at CTIO. When completed in late 2005, PROMPT will consist of six 0.41-meter diameter Ritchey-Chretien telescopes on rapidly slewing mounts that respond to GRB alerts within seconds, when the afterglow is potentially extremely bright. Each mirror and camera coating is being optimized for a different wavelength range and function, including a NIR imager, two red-optimized imagers, a blue-optimized imager, an UV-optimized imager, and an optical polarimeter. PROMPT will be able to identify high-redshift events by dropout and distinguish these events from the similar signatures of extinction. In this way, PROMPT will act as a distance-finder scope for spectroscopic follow up on the larger 4.1-meter diameter SOAR telescope, which is also located at CTIO. When not chasing GRBs, PROMPT serves broader educational objectives across the state of North Carolina. Enclosure construction and the first two telescopes are now complete and functioning: PROMPT ...

  11. THE PHOTOSPHERIC RADIATION MODEL FOR THE PROMPT EMISSION OF GAMMA-RAY BURSTS: INTERPRETING FOUR OBSERVED CORRELATIONS

    International Nuclear Information System (INIS)

    We show that the empirical Ep-L, Γ-L, Ep-Γ, and η-barγ-Ep correlations (where L is the time-averaged luminosity of the prompt emission, Ep is the spectral peak energy, Γ is the bulk Lorentz factor, and η-barγ is the emission efficiency of gamma-ray bursts, GRBs) are well consistent with the relations between the analogous parameters predicted in the photospheric radiation model of the prompt emission of GRBs. The time-resolved thermal radiation of GRB 090902B does follow the Ep-L and Γ-L correlations. A reliable interpretation of the four correlations in alternative models is still lacking. These may point toward a photospheric origin of prompt emission of some GRBs.

  12. Contribution to the study of prompt gamma-rays from fission

    International Nuclear Information System (INIS)

    This PhD thesis has essentially been motivated by the nuclear heating problematic in reactors. The main goal of this work was the production of methods capable of simulating the prompt gamma emission from fission. First of all, several algorithms for the treatment of the nucleus deexcitation were implemented. They have been successfully tested through various calculations (isomeric branching ratio, total radiative width, etc). These methods were then incorporated in the frame of the fission code FIFRELIN. The tool which results from this work, enables the determination of numerous fission observables in the frame of a single consistent model. A sensitivity study of the results to several numerical and nuclear models has been realized. At last, calculation have been lead for the 252Cf spontaneous fission and the thermal neutron induced fission of 235U and 239Pu. The prompt gamma spectra obtained for those three fissioning systems have been determined. The results are in good agreement with available experimental data, including recent measurements published in 2012 and 2013. (author)

  13. neutron radiography

    International Nuclear Information System (INIS)

    Neutron radiography (or radiology) is a diverse filed that uses neutrons of various energies, subthermal, thermal, epithermal or fast in either steady state or pulsed mode to examine objects for industrial, medical, or other purposes, both microscopic and macroscopic. The applications include engineering design, biological studies, nondestructive inspection and materials evaluation. In the past decade, over 100 different centers in some 30 countries have published reports of pioneering activities using reactors, accelerators and isotopic neutron sources. While film transparency and electronic video are most common imaging methods for static or in motion objects respectively, there are other important data gathering techniques, including track etch, digital gauging and computed tomography. A survey of the world-wide progress shows the field to be gaining steadily in its diversity, its sophistication and its importance. (author)

  14. Cycle Average Peak Fuel Temperature Prediction Using CAPP/GAMMA+

    Energy Technology Data Exchange (ETDEWEB)

    Tak, Nam-il; Lee, Hyun Chul; Lim, Hong Sik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    In order to obtain a cycle average maximum fuel temperature without rigorous efforts, a neutronics/thermo-fluid coupled calculation is needed with depletion capability. Recently, a CAPP/GAMMA+ coupled code system has been developed and the initial core of PMR200 was analyzed using the CAPP/GAMMA+ code system. The GAMMA+ code is a system thermo-fluid analysis code and the CAPP code is a neutronics code. The General Atomics proposed that the design limit of the fuel temperature under normal operating conditions should be a cycle-averaged maximum value. Nonetheless, the existing works of Korea Atomic Energy Research Institute (KAERI) only calculated the maximum fuel temperature at a fixed time point, e.g., the beginning of cycle (BOC) just because the calculation capability was not ready for a cycle average value. In this work, a cycle average maximum fuel temperature has been calculated using CAPP/GAMMA+ code system for the equilibrium core of PMR200. The CAPP/GAMMA+ coupled calculation was carried out for the equilibrium core of PMR 200 from BOC to EOC to obtain a cycle average peak fuel temperature. The peak fuel temperature was predicted to be 1372 .deg. C near MOC. However, the cycle average peak fuel temperature was calculated as 1181 .deg. C, which is below the design target of 1250 .deg. C.

  15. Spectroscopy of neutron rich nuclei using cold neutron induced fission of actinide targets at the ILL: the EXILL campaign

    OpenAIRE

    de France G.; Blanc A.; Drouet F.; Jentschel M.; Köster U.; Mutti P.; Régis J.M.; Simpson G.; Soldner T.; Stezowski O.; Ur C.A.; Urban W.; Vancrayenest A.

    2014-01-01

    A combination of germanium detectors has been installed at the PF1B neutron guide of the ILL to perform the prompt spectroscopy of neutron-rich nuclei produced in the neutron-capture induced-fission of 235U and 241Pu. In addition LaBr3 detectors from the FATIMA collaboration have been installed in complement with the EXOGAM clovers to measure lifetimes of low-lying excited states. The measured characteristics and online spectra indicate very good performances of the overall setup.

  16. Spectroscopy of neutron rich nuclei using cold neutron induced fission of actinide targets at the ILL: the EXILL campaign

    Directory of Open Access Journals (Sweden)

    de France G.

    2014-03-01

    Full Text Available A combination of germanium detectors has been installed at the PF1B neutron guide of the ILL to perform the prompt spectroscopy of neutron-rich nuclei produced in the neutron-capture induced-fission of 235U and 241Pu. In addition LaBr3 detectors from the FATIMA collaboration have been installed in complement with the EXOGAM clovers to measure lifetimes of low-lying excited states. The measured characteristics and online spectra indicate very good performances of the overall setup.

  17. Gaussian moving averages and semimartingales

    DEFF Research Database (Denmark)

    Basse-O'Connor, Andreas

    2008-01-01

    In the present paper we study moving averages (also known as stochastic convolutions) driven by a Wiener process and with a deterministic kernel. Necessary and sufficient conditions on the kernel are provided for the moving average to be a semimartingale in its natural filtration. Our results...... are constructive - meaning that they provide a simple method to obtain kernels for which the moving average is a semimartingale or a Wiener process. Several examples are considered. In the last part of the paper we study general Gaussian processes with stationary increments. We provide necessary and sufficient...

  18. Neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

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

  19. Neutron kinetics in moderators and SNM detection through epithermal-neutron-induced fissions

    Science.gov (United States)

    Gozani, Tsahi; King, Michael J.

    2016-01-01

    Extension of the well-established Differential Die Away Analysis (DDAA) into a faster time domain, where more penetrating epithermal neutrons induce fissions, is proposed and demonstrated via simulations and experiments. In the proposed method the fissions stimulated by thermal, epithermal and even higher-energy neutrons are measured after injection of a narrow pulse of high-energy 14 MeV (d,T) or 2.5 MeV (d,D) source neutrons, appropriately moderated. The ability to measure these fissions stems from the inherent correlation of neutron energy and time ("E-T" correlation) during the process of slowing down of high-energy source neutrons in common moderating materials such as hydrogenous compounds (e.g., polyethylene), heavy water, beryllium and graphite. The kinetic behavior following injection of a delta-function-shaped pulse (in time) of 14 MeV neutrons into such moderators is studied employing MCNPX simulations and, when applicable, some simple "one-group" models. These calculations served as a guide for the design of a source moderator which was used in experiments. Qualitative relationships between slowing-down time after the pulse and the prevailing neutron energy are discussed. A laboratory system consisting of a 14 MeV neutron generator, a polyethylene-reflected Be moderator, a liquid scintillator with pulse-shape discrimination (PSD) and a two-parameter E-T data acquisition system was set up to measure prompt neutron and delayed gamma-ray fission signatures in a 19.5% enriched LEU sample. The measured time behavior of thermal and epithermal neutron fission signals agreed well with the detailed simulations. The laboratory system can readily be redesigned and deployed as a mobile inspection system for SNM in, e.g., cars and vans. A strong pulsed neutron generator with narrow pulse (fission modality a realizable SNM detection technique.

  20. Gamma Ray Burst engine activity within the quark nova scenario: Prompt emission, X-ray Plateau, and sharp drop-off

    OpenAIRE

    Staff, Jan; Niebergal, Brian; Ouyed, Rachid

    2007-01-01

    We present a three-stage model for a long GRB inner engine to explain the prompt gamma ray emission, and interpret recent Swift satellite observations of early X-ray afterglow plateaus followed by a sharp drop off or a shallow power law decay. The three stages involves a neutron star phase, a quark star (QS) and a black hole phase as described in Staff et al. (2007). We find that the QS stage allows for more energy to be extracted from neutron star to QS conversion as well as from ensuing acc...

  1. Limits on optical polarization during the prompt phase of GRB 140430A

    CERN Document Server

    Kopac, D; Japelj, J; Arnold, D M; Steele, I A; Guidorzi, C; Dichiara, S; Kobayashi, S; Gomboc, A; Harrison, R M; Lamb, G P; Melandri, A; Smith, R J; Virgili, F J; Castro-Tirado, A J; Gorosabel, J; Jarvinen, A; Sanchez-Ramirez, R; Oates, S R; Jelinek, M

    2015-01-01

    Gamma-ray burst GRB 140430A was detected by the Swift satellite and observed promptly with the imaging polarimeter RINGO3 mounted on the Liverpool Telescope, with observations beginning while the prompt $\\gamma$-ray emission was still ongoing. In this paper, we present densely sampled (10-second temporal resolution) early optical light curves in 3 optical bands and limits to the degree of optical polarization. We compare optical, X-ray and gamma-ray properties and present an analysis of the optical emission during a period of high-energy flaring. The complex optical light curve cannot be explained merely with a combination of forward and reverse shock emission from a standard external shock, implying additional contribution of emission from internal shock dissipation. We estimate an upper limit for time averaged optical polarization during the prompt phase to be as low as P < 12% (1$\\sigma$). This suggests that the optical flares and early afterglow emission in this GRB are not highly polarized. Alternativ...

  2. NaI detector neutron activation spectra for PGNAA applications

    Science.gov (United States)

    Gardner; El; Zheng; Hayden; Mayo

    2000-10-01

    When NaI detectors are used in prompt gamma-ray neutron activation analysis devices, they are activated by neutrons that penetrate the detector. While thermal neutron filters like boron or lithium can be used to reduce this activation, it can never be completely eliminated by this approach since high energy neutrons can penetrate the detector and thermalize inside it. This activation results in the emission of prompt gamma rays from both the I and Na and the production of the radioisotopes 128I and 24Na that subsequently decay and emit their characteristic beta particles and gamma rays. The resulting three spectra represent a background for this measurement. An experimental method for obtaining these three spectra is described and results are reported for 2" x 2", 5" x 5", 6" x 6", and 1" x 6" NaI detectors using the thermal neutron beam of the NCSU PULSTAR nuclear reactor. In addition, Monte Carlo simulation programs have been developed and used for simulating these spectra. Good results have been obtained by the Monte Carlo method for the two radioisotope spectra, and it is anticipated that good results will also be obtained for the prompt gamma-ray spectrum when the I and Na coincidence schemes are known. PMID:11003483

  3. NaI detector neutron activation spectra for PGNAA applications

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, R.P. E-mail: gardner@ncsu.edu; Sayyed, El; Zheng Yuanshui; Hayden, Stephanie; Mayo, C.W

    2000-11-15

    When NaI detectors are used in prompt gamma-ray neutron activation analysis devices, they are activated by neutrons that penetrate the detector. While thermal neutron filters like boron or lithium can be used to reduce this activation, it can never be completely eliminated by this approach since high energy neutrons can penetrate the detector and thermalize inside it. This activation results in the emission of prompt gamma rays from both the I and Na and the production of the radioisotopes {sup 128}I and {sup 24}Na that subsequently decay and emit their characteristic beta particles and gamma rays. The resulting three spectra represent a background for this measurement. An experimental method for obtaining these three spectra is described and results are reported for 2x2, 5x5, 6x6, and 1x6 NaI detectors using the thermal neutron beam of the NCSU PULSTAR nuclear reactor. In addition, Monte Carlo simulation programs have been developed and used for simulating these spectra. Good results have been obtained by the Monte Carlo method for the two radioisotope spectra, and it is anticipated that good results will also be obtained for the prompt gamma-ray spectrum when the I and Na coincidence schemes are known.

  4. Prompts to eat novel and familiar fruits and vegetables in families with 1-3 year-old children: Relationships with food acceptance and intake.

    Science.gov (United States)

    Edelson, Lisa R; Mokdad, Cassandra; Martin, Nathalie

    2016-04-01

    Toddlers often go through a picky eating phase, which can make it difficult to introduce new foods into the diet. A better understanding of how parents' prompts to eat fruits and vegetables are related to children's intake of these foods will help promote healthy eating habits. 60 families recorded all toddler meals over one day, plus a meal in which parents introduced a novel fruit/vegetable to the child. Videos were coded for parent and child behaviors. Parents completed a feeding style questionnaire and three 24-h dietary recalls about their children's intake. Parents made, on average, 48 prompts for their children to eat more during the main meals in a typical day, mostly of the neutral type. Authoritarian parents made the most prompts, and used pressure the most often. In the novel food situation, it took an average of 2.5 prompts before the child tasted the new food. The most immediately successful prompt for regular meals across food types was modeling. There was a trend for using another food as a reward to work less well than a neutral prompt for encouraging children to try a novel fruit or vegetable. More frequent prompts to eat fruits and vegetables during typical meals were associated with higher overall intake of these food groups. More prompts for children to try a novel vegetable was associated with higher overall vegetable intake, but this pattern was not seen for fruits, suggesting that vegetable variety may be more strongly associated with intake. Children who ate the most vegetables had parents who used more "reasoning" prompts, which may have become an internalized motivation to eat these foods, but this needs to be tested explicitly using longer-term longitudinal studies.

  5. Power convergence of Abel averages

    OpenAIRE

    Kozitsky, Yuri; Shoikhet, David; Zemanek, Jaroslav

    2012-01-01

    Necessary and sufficient conditions are presented for the Abel averages of discrete and strongly continuous semigroups, $T^k$ and $T_t$, to be power convergent in the operator norm in a complex Banach space. These results cover also the case where $T$ is unbounded and the corresponding Abel average is defined by means of the resolvent of $T$. They complement the classical results by Michael Lin establishing sufficient conditions for the corresponding convergence for a bounded $T$.

  6. The physics experimental study for in-hospital neutron irradiator

    International Nuclear Information System (INIS)

    MNSRs (Miniature Neutron Source Reactor) are low power research reactors designed and manufactured by China Institute of Atomic Energy (CIAE). MNSRs are mainly used for NAA, training and teaching, testing of nuclear instrumentation. The first MNSR, the prototype MNSR, was put into operation in 1984, later, eight other MNSRs had been built both at home and abroad. For MNSRs, highly enriched uranium (90%) is used as the fuel material. The In-Hospital Neutron Irradiator (IHNI) is designed for Boron Neutron Capture Therapy (BNCT) based on Miniature Neutron Source Reactor(MNSR). On both sides of the reactor core, there are two neutron beams, one is thermal neutron beam, and the other opposite to the thermal beam, is epithermal neutron beam. A small thermal neutron beam is specially designed for the measurement of blood boron concentration by the prompt gamma neutron activation analysis (PGNAA). In this paper, the experimental results of critical mass worth of the top Be reflectors worth of the control rod, neutron flux distribution and other components worth were measured, the experiment was done on the Zero Power Experiment equipment of MNSR. (author)

  7. Average resonance parameters of germanium and selenium nuclei

    International Nuclear Information System (INIS)

    Full sets of average resonance parameters S0, S1, R0', R1', S1,3/2 for germanium and selenium nuclei with natural isotope content are determined. Parameters are received from the analysis of experimental neutron elastic scattering cross sections at energy region up to 440 keV with the help of the method developed by the authors. The analysis of recommended parameters and some literature data is fulfilled as well.

  8. Average resonance parameters of tellurium and neodymium nuclei

    International Nuclear Information System (INIS)

    Complete sets of average resonance parameters S0, S1, R''0, R''1, and S1,3/2 for tellurium and neodymium nuclei with natural isotope contents have been determined by analyzing the experimental differential cross-sections of neutron elastic scattering in the energy range lower than 440 keV. The data obtained, the recommended parameter values, and some literature data have been analyzed.

  9. New developments in APSTNG neutron probe diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Rhodes, E.; Dickerman, C.E.

    1995-12-31

    The development and investigation of a small associated-particle sealed-tube neutron generator (APSTNG) show potential to allow the associated-particle diagnostic method to be moved out of the laboratory into field applications. The APSTNG interrogates the inspected object with 14-MeV neutrons generated from the deuterium-tritium reaction and detects the alpha-particle associated with each neutron inside a cone encompassing the region of interest. Gamma-ray spectra of resulting neutron reactions identify many nuclides. Flight-times determined from detection times of the gamma-rays and alpha-particles separate the prompt and delayed gamma-ray spectra and can yield a separate coarse tomographic image of each identified nuclide, from a single orientation. Chemical substances are identified by comparing relative spectral line intensities with ratios of elements in reference compounds. The high-energy neutrons and gamma-rays penetrate large objects and dense materials. The gamma-ray dector and neutron generator can be located on the same side of the interrogated object, so spaces behind walls and other confirmed areas can be inspected. No collimators or radiation shielding are needed, the neutron generator is relatively simple and small, and commercial-grade electronics are employed. A complete system could be transported in an automotive van. Proof-of-concept laboratory experiments have been successfully performed for simulated nuclear, chemical warfare, and conventional munitions. Inspection applications have been investigated for presence of cocaine in propane tanks, uranium and plutonium smuggling, and radioactive and toxic waste characterization. An advanced APSTNG tube is being designed and constructed that will be transportable and rugged, yield a substantial neutron output increase, and provide sufficiently improved lifetime to allow operation at more than an order of magnitude increase in neutron flux.

  10. Monitoring the Bragg peak location of 73 MeV/u carbon ions by means of prompt $\\gamma$-ray measurements

    CERN Document Server

    Testa, E; Chevallier, M; Dauvergne, D; Foulher, F Le; Poizat, J -C; Ray, C; Testa, M; Freud, N; Létang, J -M

    2008-01-01

    By means of a time-of-flight technique, we measured the longitudinal profile of prompt $\\gamma$-rays emitted by 73 MeV/u $^{13}$C ions irradiating a PMMA target. This technique allowed us to minimize the shielding against neutrons and scattered $\\gamma$-rays, and to correlate prompt gamma emission to the ion path. This correlation, together with a high counting rate, paves the way toward real-time monitoring of the longitudinal dose profile during ion therapy treatments. Moreover, the time correlation between the prompt gamma detection and the transverse position of the incident ions measured by a beam monitor can provide real-time 3D control of the irradiation.

  11. 反应性阶跃方法测量次临界反应性%Measurement of Reactivity at Subcriticality by Reactivity Prompt Jump Method

    Institute of Scientific and Technical Information of China (English)

    尹延朋; 龚建; 郑春

    2012-01-01

    反应性阶跃法和落棒法相似,均通过快速改变控制棒的位置快速改变反应堆反应性,但在实验条件上存在较大差异.本文以6群缓发中子点堆方程为基础,反应性阶跃假定为条件,得到了反应性阶跃法所适用的反应性方程,并采用CFBR-Ⅱ堆实验数据验证了该方法.%Similar with rod drop method, reactivity is changed by moving a control rod rapidly with reactivity prompt jump method. Base on 6 groups delayed neutron point kinetics equations, the reactivity equation was deduced by assuming reactivity prompt jump. And the prompt jump method was validated by experimental data on CFBR-K .

  12. FIssion Product Prompt γ-ray spectrometer: Development of an instrumented gas-filled magnetic spectrometer at the ILL

    Science.gov (United States)

    Blanc, A.; Chebboubi, A.; Faust, H.; Jentschel, M.; Kessedjian, G.; Köster, U.; Materna, T.; Panebianco, S.; Sage, C.; Urban, W.

    2013-12-01

    Accurate thermal neutron-induced fission data are important for applications in reactor physics as well as for fundamental nuclear physics. FIPPS is the new FIssion Product Prompt γ-ray Spectrometer being developed at the Institut Laue Langevin for neutron-induced fission studies. FIPPS is based on the combination of a large Germanium detector array surrounding a fission target, a Time-Of-Flight detector and a Gas-Filled Magnet (GFM) to identify mass, nuclear charge and kinetic energy of one of the fission fragments. The GFM will be instrumented with a Time-Projection Chamber (TPC) for individual 3D tracking of the fragments. A conceptual design study of the new spectrometer is presented.

  13. Radiochemical measurement of neutron-spectrum averaged cross sections for the formation of {sup 64}Cu and {sup 67}Cu via the (n,p) reaction at a TRIGA Mark-II reactor. Feasibility of simultaneous production of the theragnostic pair {sup 64}Cu/{sup 67}Cu

    Energy Technology Data Exchange (ETDEWEB)

    Uddin, M. Shuza; Hossain, Syed Mohammod [Atomic Energy Research Establishment, Dhaka (Bangladesh). Inst. of Nuclear Science and Technology; Rumman-uz-Zaman, M. [Atomic Energy Research Establishment, Dhaka (Bangladesh). Inst. of Nuclear Science and Technology; Dhaka Univ. (Bangladesh). Dept. of Applied Chemistry and Chemical Engineering; Qaim, Syed M. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Neurowissenschaften und Medizin (INM-5) - Nuklearchemie

    2014-09-01

    Integral cross sections of the {sup 64}Zn(n,p){sup 64}Cu and {sup 67}Zn(n,p){sup 67}Cu reactions were measured for the fast neutron spectrum of TRIGA Mark-II reactor at Savar, Dhaka, Bangladesh. A clean radiochemical separation was performed to isolate the copper radionuclides from the target element zinc. The radioactivities produced in the irradiation were measured by HPGe γ-ray spectroscopy. The neutron flux over the energy range 0.5-20 MeV was determined using the {sup 58}Ni(n,p){sup 58}Co monitor reaction. The measured results amount to 28.9 ± 2.0 mb and 0.84 ± 0.07 mb for the formation of {sup 64}Cu and {sup 67}Cu, respectively. These values are slightly lower than the respective values for a pure fission spectrum. The present results were compared with data calculated using the neutron spectral distribution and the recently critically analysed excitation function of each reaction given in the literature. The good agreement validates the reliability of those excitation functions. The feasibility of simultaneous production of {sup 64}Cu and {sup 67}Cu with fast neutrons is discussed. (orig.)

  14. New features in cold neutron radiography and tomography Part II: applied energy-selective neutron radiography and tomography

    International Nuclear Information System (INIS)

    The neutron attenuation coefficient drops for many solid materials quite drastically at a defined cold neutron energy known as a Bragg-cut-off in the cross-section diagrams. In many cases, the drop in attenuation for the corresponding elements is significant and this behavior can be exploited to change the material contrast in radiography and tomography images by modifying the spectrum of the applied neutron beam. The energy-dependent experiments were performed at the Prompt Gamma-ray Activation beam line where the irradiation position is at the end of a curved neutron guide, which delivers cold neutrons from the spallation source SINQ (PSI, Switzerland). This beam position gave the opportunity to perform radiography and tomography at low neutron energies. An effective monochromatization of the primary neutron beam was obtained by using a neutron velocity selector. The intensity of the modified beam was still reasonable for radiography images at different neutron energies and the experiments were performed in relatively short measuring times. A variety of samples were studied to illustrate possible applications of energy-selective radiography and tomography. This new neutron imaging technique provided encouraging results and projects of developing permanent facilities for such investigations at PSI and FRM II are under study

  15. Stellar 30-keV neutron capture in 94,96Zr and the 90Zr(gamma,n)89Zr photonuclear reaction with a high-power liquid-lithium target

    CERN Document Server

    Tessler, M; Arenshtam, A; Feinberg, G; Friedman, M; Halfon, S; Kijel, D; Weissman, L; Aviv, O; Berkovits, D; Eisen, Y; Eliyahu, I; Haquin, G; Kreisel, A; Mardor, I; Shimel, G; Shor, A; Silverman, I; Yungrais, Z

    2015-01-01

    A high-power Liquid-Lithium Target (LiLiT) was used for the first time for neutron production via the thick-target 7Li(p,n)7Be reaction and quantitative determination of neutron capture cross sections. Bombarded with a 1-2 mA proton beam at 1.92 MeV from the Soreq Applied Research Accelerator Facility (SARAF), the setup yields a 30-keV quasi-Maxwellian neutron spectrum with an intensity of 3-5e10 n/s, more than one order of magnitude larger than present near-threshold 7Li(p,n) neutron sources. The setup was used here to determine the 30-keV Maxwellian averaged cross section (MACS) of 94Zr and 96Zr as 28.0+-0.6 mb and 12.4+-0.5 mb respectively, based on activation measurements. The precision of the cross section determinations results both from the high neutron yield and from detailed simulations of the entire experimental setup. We plan to extend our experimental studies to low-abundance and radioactive targets. In addition, we show here that the setup yields intense high-energy (17.6 and 14.6 MeV) prompt cap...

  16. Time-resolved imaging of prompt-gamma rays for proton range verification using a knife-edge slit camera based on digital photon counters

    OpenAIRE

    Cambraia Lopes, P; Clementel, E; Crespo, P; Henrotin, S; Huizenga, J.; G. Janssens; Parodi, K.; Prieels, D.; Roellinghoff, F; Smeets, J.; Stichelbaut, F.; Schaart, D. R.

    2015-01-01

    Proton range monitoring may facilitate online adaptive proton therapy and improve treatment outcomes. Imaging of proton-induced prompt gamma (PG) rays using a knife-edge slit collimator is currently under investigation as a potential tool for real-time proton range monitoring. A major challenge in collimated PG imaging is the suppression of neutron-induced background counts. In this work, we present an initial performance test of two knife-edge slit camera prototypes based on arrays of digita...

  17. Evaluation of prompt gamma-ray data and nuclear structure of niobium-94 with statistical model calculations

    Science.gov (United States)

    Turkoglu, Danyal

    Precise knowledge of prompt gamma-ray intensities following neutron capture is critical for elemental and isotopic analyses, homeland security, modeling nuclear reactors, etc. A recently-developed database of prompt gamma-ray production cross sections and nuclear structure information in the form of a decay scheme, called the Evaluated Gamma-ray Activation File (EGAF), is under revision. Statistical model calculations are useful for checking the consistency of the decay scheme, providing insight on its completeness and accuracy. Furthermore, these statistical model calculations are necessary to estimate the contribution of continuum gamma-rays, which cannot be experimentally resolved due to the high density of excited states in medium- and heavy-mass nuclei. Decay-scheme improvements in EGAF lead to improvements to other databases (Evaluated Nuclear Structure Data File, Reference Input Parameter Library) that are ultimately used in nuclear-reaction models to generate the Evaluated Nuclear Data File (ENDF). Gamma-ray transitions following neutron capture in 93Nb have been studied at the cold-neutron beam facility at the Budapest Research Reactor. Measurements have been performed using a coaxial HPGe detector with Compton suppression. Partial gamma-ray production capture cross sections at a neutron velocity of 2200 m/s have been deduced relative to that of the 255.9-keV transition after cold-neutron capture by 93Nb. With the measurement of a niobium chloride target, this partial cross section was internally standardized to the cross section for the 1951-keV transition after cold-neutron capture by 35Cl. The resulting (0.1377 +/- 0.0018) barn (b) partial cross section produced a calibration factor that was 23% lower than previously measured for the EGAF database. The thermal-neutron cross sections were deduced for the 93Nb(n,gamma ) 94mNb and 93Nb(n,gamma) 94gNb reactions by summing the experimentally-measured partial gamma-ray production cross sections associated

  18. Methods for absorbing neutrons

    Science.gov (United States)

    Guillen, Donna P.; Longhurst, Glen R.; Porter, Douglas L.; Parry, James R.

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  19. Strategies for Finding Prompt Radio Counterparts to Gravitational Wave Transients with the Murchison Widefield Array

    CERN Document Server

    Kaplan, D L; Rowlinson, A; Croft, S D; Wayth, R B; Trott, C M

    2016-01-01

    We present and evaluate several strategies to search for prompt, low-frequency radio emission associated with gravitational wave transients using the Murchison Widefield Array (MWA). As we are able to repoint the MWA on timescales of tens of seconds, we can search for the dispersed radio signal that has been predicted to originate along with or shortly after a neutron star-neutron star merger. We find that given the large, 600 deg^2 instantaneous field-of-view of the MWA we can cover a significant fraction of the predicted gravitational wave error region, although due to the complicated geometry of the latter we only cover >50% of the error region for approximately 5% of events, and roughly 15% of events will be located <10 deg from the MWA pointing center such that they will be covered in the radio images. For optimal conditions our limiting flux density for a 10-s long transient would be 0.1 Jy, increasing to about 1 Jy for a wider range of events. This corresponds to luminosity limits of 1e38-1e39 erg/s...

  20. Prompt gamma-ray activation technique for in-situ analysis of mercury pollution in water

    International Nuclear Information System (INIS)

    Industrial and mining pollutants discharged into water are in general distributed homogeneously and we investigated a prompt neutron activation technique for the in-situ analysis, to start with of Hg content in water. The laboratory test employed a 252 Cf neutron source (of ∼ 3 x 106 n/s fluence) submerged in a test tank of water of ∼ 500 litres, and to monitor the gamma-ray emission a 4 x 4 NaI (Tl) detector system was employed. In 3000 is time interval trials, for a 46 ppm contamination level of Hg, we observed an excess of counts of ∼ 9.2 σ significance in the energy range of 4000-6500 keV, which can be attributed to the presence of mercury. This test system for a 10 hour monitoring can provide a minimum detectable sensitivity at 4.78 ppm. In the future experiments, we propose to replace the NaI(Tl) detector by a HPGe detector to facilitate simultaneous analyses of pollutants such as cadmium, chlorine, chromium etc for detection at few tenths to tens of ppm levels or better. (author). 5 refs., 2 figs., 2 tabs

  1. Vocal attractiveness increases by averaging.

    Science.gov (United States)

    Bruckert, Laetitia; Bestelmeyer, Patricia; Latinus, Marianne; Rouger, Julien; Charest, Ian; Rousselet, Guillaume A; Kawahara, Hideki; Belin, Pascal

    2010-01-26

    Vocal attractiveness has a profound influence on listeners-a bias known as the "what sounds beautiful is good" vocal attractiveness stereotype [1]-with tangible impact on a voice owner's success at mating, job applications, and/or elections. The prevailing view holds that attractive voices are those that signal desirable attributes in a potential mate [2-4]-e.g., lower pitch in male voices. However, this account does not explain our preferences in more general social contexts in which voices of both genders are evaluated. Here we show that averaging voices via auditory morphing [5] results in more attractive voices, irrespective of the speaker's or listener's gender. Moreover, we show that this phenomenon is largely explained by two independent by-products of averaging: a smoother voice texture (reduced aperiodicities) and a greater similarity in pitch and timbre with the average of all voices (reduced "distance to mean"). These results provide the first evidence for a phenomenon of vocal attractiveness increases by averaging, analogous to a well-established effect of facial averaging [6, 7]. They highlight prototype-based coding [8] as a central feature of voice perception, emphasizing the similarity in the mechanisms of face and voice perception.

  2. Vocal attractiveness increases by averaging.

    Science.gov (United States)

    Bruckert, Laetitia; Bestelmeyer, Patricia; Latinus, Marianne; Rouger, Julien; Charest, Ian; Rousselet, Guillaume A; Kawahara, Hideki; Belin, Pascal

    2010-01-26

    Vocal attractiveness has a profound influence on listeners-a bias known as the "what sounds beautiful is good" vocal attractiveness stereotype [1]-with tangible impact on a voice owner's success at mating, job applications, and/or elections. The prevailing view holds that attractive voices are those that signal desirable attributes in a potential mate [2-4]-e.g., lower pitch in male voices. However, this account does not explain our preferences in more general social contexts in which voices of both genders are evaluated. Here we show that averaging voices via auditory morphing [5] results in more attractive voices, irrespective of the speaker's or listener's gender. Moreover, we show that this phenomenon is largely explained by two independent by-products of averaging: a smoother voice texture (reduced aperiodicities) and a greater similarity in pitch and timbre with the average of all voices (reduced "distance to mean"). These results provide the first evidence for a phenomenon of vocal attractiveness increases by averaging, analogous to a well-established effect of facial averaging [6, 7]. They highlight prototype-based coding [8] as a central feature of voice perception, emphasizing the similarity in the mechanisms of face and voice perception. PMID:20129047

  3. Measurements of fast neutron-induced fission data of Np-237

    Energy Technology Data Exchange (ETDEWEB)

    Win, Than; Saito, Keiichiro; Baba, Mamoru; Iwasaki, Tomohiko; Ibaraki, Masanobu; Miura, Takako; Sanami, Toshiya; Nauchi, Yasushi; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

    1998-03-01

    We have performed the following measurements for {sup 237}Np using the 4.5 MV Dynamitron accelerator of Tohoku University as the pulsed neutron source: (1) Prompt fission neutron spectrum for 0.62 MeV incident neutrons, and (2) Neutron-Induced fission cross-section between 10 and 100 keV. The prompt fission neutron spectrum was measured using TOF method with a heavily shielded NE213 scintillation detector. The Maxwellian temperature T{sub m} derived is 1.28 MeV, which is lower than that of 1.38 MeV in JENDL-3.2. The fission cross sections were measured between 10 - 100 keV. The results are between JENDL-3.2 and ENDF/B-VI. (author)

  4. Relativistic Simulations of Eccentric Binary Neutron Star Mergers: One-arm Spiral Instability and Effects of Neutron Star Spin

    CERN Document Server

    East, William E; Pretorius, Frans; Shapiro, Stuart L

    2016-01-01

    We perform general-relativistic hydrodynamical simulations of dynamical capture binary neutron star mergers, emphasizing the role played by the neutron star spin. Dynamical capture mergers may take place in globular clusters, as well as other dense stellar systems, where most neutron stars have large spins. We find significant variability in the merger outcome as a function of initial neutron star spin. For cases where the spin is aligned with the orbital angular momentum, the additional centrifugal support in the remnant hypermassive neutron star can prevent the prompt collapse to a black hole, while for antialigned cases the decreased total angular momentum can facilitate the collapse to a black hole. We show that even moderate spins can significantly increase the amount of ejected material, including the amount unbound with velocities greater than half the speed of light, leading to brighter electromagnetic signatures associated with kilonovae and interaction of the ejecta with the interstellar medium. Fur...

  5. Sparsity Averaging for Compressive Imaging

    CERN Document Server

    Carrillo, Rafael E; Van De Ville, Dimitri; Thiran, Jean-Philippe; Wiaux, Yves

    2012-01-01

    We propose a novel regularization method for sparse image reconstruction from compressive measurements. The approach relies on the conjecture that natural images exhibit strong average sparsity over multiple coherent frames. The associated reconstruction algorithm, based on an analysis prior and a reweighted $\\ell_1$ scheme, is dubbed Sparsity Averaging Reweighted Analysis (SARA). We test our prior and the associated algorithm through extensive numerical simulations for spread spectrum and Gaussian acquisition schemes suggested by the recent theory of compressed sensing with coherent and redundant dictionaries. Our results show that average sparsity outperforms state-of-the-art priors that promote sparsity in a single orthonormal basis or redundant frame, or that promote gradient sparsity. We also illustrate the performance of SARA in the context of Fourier imaging, for particular applications in astronomy and medicine.

  6. Neutron moderation in a bulk sample and its effects on PGNAA setup geometry

    International Nuclear Information System (INIS)

    In a prompt gamma ray neutron activation analysis (PGNAA) setup, the neutron moderation in the bulk sample also plays a key role. This can even dominate the thermalization effects of the external moderator in some cases. In order to study the neutron moderation effect in the bulk sample, moderators with two different sizes of the sample were tested at the King Fahd University of Petroleum and Minerals (KFUPM) PGNAA facility. In these tests, the thermal neutron relative intensity and prompt gamma ray yield from the two moderators were measured using nuclear track detectors (NTDs) and NaI detector, respectively. As predicted by Monte Carlo simulations, the measured intensity of thermal neutron inside the large sample cavity due to the external moderator was smaller than that from the smaller sample cavity. Due to its larger size, additional thermalization of neutrons will take place in the larger sample. In spite of smaller thermal neutron yield from the external moderator at the large sample location, higher yield of the prompt gamma ray was observed as compared to that from the smaller sample. This confirms the significance of neutron moderation effects in the bulk sample and can thereby affect the PGNAA geometry size. This allows larger samples in conjunction with smaller moderators in the PGNAA setup

  7. Neutron moderation in a bulk sample and its effects on PGNAA setup geometry

    Energy Technology Data Exchange (ETDEWEB)

    Al-Jarallah, M.I. E-mail: mibrahim@kfupm.edu.sa; Naqvi, A.A.; Fazal-ur-Rehman,; Maselehuddin, M.; Abu-Jarad, F.; Raashid, M

    2003-06-01

    In a prompt gamma ray neutron activation analysis (PGNAA) setup, the neutron moderation in the bulk sample also plays a key role. This can even dominate the thermalization effects of the external moderator in some cases. In order to study the neutron moderation effect in the bulk sample, moderators with two different sizes of the sample were tested at the King Fahd University of Petroleum and Minerals (KFUPM) PGNAA facility. In these tests, the thermal neutron relative intensity and prompt gamma ray yield from the two moderators were measured using nuclear track detectors (NTDs) and NaI detector, respectively. As predicted by Monte Carlo simulations, the measured intensity of thermal neutron inside the large sample cavity due to the external moderator was smaller than that from the smaller sample cavity. Due to its larger size, additional thermalization of neutrons will take place in the larger sample. In spite of smaller thermal neutron yield from the external moderator at the large sample location, higher yield of the prompt gamma ray was observed as compared to that from the smaller sample. This confirms the significance of neutron moderation effects in the bulk sample and can thereby affect the PGNAA geometry size. This allows larger samples in conjunction with smaller moderators in the PGNAA setup.

  8. A quantitative PGNAA study for use in aqueous solution measurements using Am-Be neutron source and BGO scintillation detector

    Science.gov (United States)

    Ghal-Eh, N.; Ahmadi, P.; Doost-Mohammadi, V.

    2016-02-01

    A prompt gamma neutron activation analysis (PGNAA) system including an Am-Be neutron source and BGO scintillation detector are used for quantitative analysis of bulk samples. Both Monte Carlo-simulated and experimental data are considered as input data libraries for two different procedures based on neural network and least squares methods. The results confirm the feasibility and precision of the proposed methods.

  9. Coupled multi-group neutron photon transport for the simulation of high-resolution gamma-ray spectroscopy applications

    Energy Technology Data Exchange (ETDEWEB)

    Burns, Kimberly A. [Georgia Inst. of Technology, Atlanta, GA (United States)

    2009-08-01

    The accurate and efficient simulation of coupled neutron-photon problems is necessary for several important radiation detection applications. Examples include the detection of nuclear threats concealed in cargo containers and prompt gamma neutron activation analysis for nondestructive determination of elemental composition of unknown samples.

  10. Initial global 2-D shielding analysis for the Advanced Neutron Source core and reflector

    Energy Technology Data Exchange (ETDEWEB)

    Bucholz, J.A.

    1995-08-01

    This document describes the initial global 2-D shielding analyses for the Advanced Neutron Source (ANS) reactor, the D{sub 2}O reflector, the reflector vessel, and the first 200 mm of light water beyond the reflector vessel. Flux files generated here will later serve as source terms in subsequent shielding analyses. In addition to reporting fluxes and other data at key points of interest, a major objective of this report was to document how these analyses were performed, the phenomena that were included, and checks that were made to verify that these phenomena were properly modeled. In these shielding analyses, the fixed neutron source distribution in the core was based on the `lifetime-averaged` spatial power distribution. Secondary gamma production cross sections in the fuel were modified so as to account intrinsically for delayed fission gammas in the fuel as well as prompt fission gammas. In and near the fuel, this increased the low-energy gamma fluxes by 50 to 250%, but out near the reflector vessel, these same fluxes changed by only a few percent. Sensitivity studies with respect to mesh size were performed, and a new 2-D mesh distribution developed after some problems were discovered with respect to the use of numerous elongated mesh cells in the reflector. All of the shielding analyses were performed sing the ANSL-V 39n/44g coupled library with 25 thermal neutron groups in order to obtain a rigorous representation of the thermal neutron spectrum throughout the reflector. Because of upscatter in the heavy water, convergence was very slow. Ultimately, the fission cross section in the various materials had to be artificially modified in order to solve this fixed source problem as an eigenvalue problem and invoke the Vondy error-mode extrapolation technique which greatly accelerated convergence in the large 2-D RZ DORT analyses. While this was quite effective, 150 outer iterations (over energy) were still required.

  11. Neutron rich nuclei and neutron stars

    OpenAIRE

    Horowitz, C. J.

    2013-01-01

    The PREX experiment at Jefferson Laboratory measures the neutron radius of 208Pb with parity violating electron scattering in a way that is free from most strong interaction uncertainties. The 208Pb radius has important implications for neutron rich matter and the structure of neutron stars. We present first PREX results, describe future plans, and discuss a follow on measurement of the neutron radius of 48Ca. We review radio and X-ray observations of neutron star masses and radii. These cons...

  12. Prompt gamma-ray 3D-imaging for cultural heritage purposes

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, Ralf

    2010-07-01

    The development of new, and the enhancement of existing element-sensitive imaging methods utilizing neutrons of different energy regions was the aim of the European ANCIENT CHARM project. During the present work the setup for Prompt Gamma-ray Activation Analysis (PGAA) at the research reactor FRM2 in Garching near Munich was modified to enable the spatial mapping of elemental abundances in the analysed samples. Because the PGAA setup at FRM2 was under construction at the beginning of the project first tests and the development of calibration and measurement procedures for the new imaging method were done by the PGAA group at the Budapest Research Reactor in cooperation with the Institute for Nuclear Physics of the University of Cologne. Due to the higher neutron flux at the PGAA setup at FRM2 the equipment was transferred from the Budapest Research Reactor to FRM2 after the PGAA setup at FRM2 started its regular operation. After further optimizations and the characterization of the setup, measurements were started on replicas of real archaeological objects before several measurements on real objects were performed and analysed. Several measurement configurations were applied. Additional to 2D and 3D imaging measurements a new application for the measurement of thin surface layers in the order of a few 100 {mu}m was developed. For the quantitative analysis of elemental distributions the exact knowledge of the neutron flux at each measured position in the analysed sample has to be known. Based on the well-established cold Neutron Tomography (NT) method a method and software have been developed, which enables the calculation of the neutron flux inside samples with the map of attenuation properties obtained through NT. A new data acquisition system was developed for the regular operation of the PGAA setup at FRM2, which supports traditional bulk PGAA measurements as well as measurements in the new imaging configuration. The high automation of the system allows a

  13. Prompt gamma-ray 3D-imaging for cultural heritage purposes

    International Nuclear Information System (INIS)

    The development of new, and the enhancement of existing element-sensitive imaging methods utilizing neutrons of different energy regions was the aim of the European ANCIENT CHARM project. During the present work the setup for Prompt Gamma-ray Activation Analysis (PGAA) at the research reactor FRM2 in Garching near Munich was modified to enable the spatial mapping of elemental abundances in the analysed samples. Because the PGAA setup at FRM2 was under construction at the beginning of the project first tests and the development of calibration and measurement procedures for the new imaging method were done by the PGAA group at the Budapest Research Reactor in cooperation with the Institute for Nuclear Physics of the University of Cologne. Due to the higher neutron flux at the PGAA setup at FRM2 the equipment was transferred from the Budapest Research Reactor to FRM2 after the PGAA setup at FRM2 started its regular operation. After further optimizations and the characterization of the setup, measurements were started on replicas of real archaeological objects before several measurements on real objects were performed and analysed. Several measurement configurations were applied. Additional to 2D and 3D imaging measurements a new application for the measurement of thin surface layers in the order of a few 100 μm was developed. For the quantitative analysis of elemental distributions the exact knowledge of the neutron flux at each measured position in the analysed sample has to be known. Based on the well-established cold Neutron Tomography (NT) method a method and software have been developed, which enables the calculation of the neutron flux inside samples with the map of attenuation properties obtained through NT. A new data acquisition system was developed for the regular operation of the PGAA setup at FRM2, which supports traditional bulk PGAA measurements as well as measurements in the new imaging configuration. The high automation of the system allows a

  14. Neutron Spectrometric Analysis: Characterization of 3He Detector Response and Chemometric Data Analysis of Pulse-Height Spectra

    International Nuclear Information System (INIS)

    Among many nucleonic gauges using a variety of sources such as alpha, beta, gamma, neutron or X-ray radiation, neutron-based techniques have been successfully used in landmine detection, cargo inspection and soil analysis as well as in the industrial process monitoring such as cement, glass, coal industries, etc. In general, there are three categories of neutron-based methods: fast neutron analysis (FNA), thermal neutron analysis (TNA) and neutron moderation. FNA and TNA utilize the slow or fast neutrons for the generation of characteristic prompt gamma-ray to identify the element of interest in many applications. The neutron moderation is attractive for the process monitoring of the moisture content in the bulk samples. In spite of its many advantages, the false-alarm rate of the neutron method is of great interest in the field operations

  15. Neutron Spectrometric Analysis: Characterization of {sup 3}He Detector Response and Chemometric Data Analysis of Pulse-Height Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Yun; Choi, Yong Suk; Park, Yong Joon; Song, Kyu Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-10-15

    Among many nucleonic gauges using a variety of sources such as alpha, beta, gamma, neutron or X-ray radiation, neutron-based techniques have been successfully used in landmine detection, cargo inspection and soil analysis as well as in the industrial process monitoring such as cement, glass, coal industries, etc. In general, there are three categories of neutron-based methods: fast neutron analysis (FNA), thermal neutron analysis (TNA) and neutron moderation. FNA and TNA utilize the slow or fast neutrons for the generation of characteristic prompt gamma-ray to identify the element of interest in many applications. The neutron moderation is attractive for the process monitoring of the moisture content in the bulk samples. In spite of its many advantages, the false-alarm rate of the neutron method is of great interest in the field operations.

  16. Implementation and Testing of the First Prompt Search for Gravitational Wave Transients with Electromagnetic Counterparts

    Science.gov (United States)

    Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adhikari, R.; Affeldt, C.; Agathos, M.; Ajith, P.; Allen, B.; Allen, G. S.; Ceron, E. Amador; Amariutei, D.; Amin, R. S.; Anderson, S. B.; Anderson, W. G.; Araya, M. C.; Aston, S. M.; Astone, P.; Atkinson, D.; Aufmuth, P.; Blackburn, L.

    2012-01-01

    Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations. Methods. During two observing periods (Dec. 17, 2009 to Jan. 8, 2010 and Sep. 2 to Oct. 20, 2010), a low-latency analysis pipeline was used to identify GW event candidates and to reconstruct maps of possible sky locations. A catalog of nearby galaxies and MilkyWay globular clusters was used to select the most promising sky positions to be imaged, and this directional information was delivered to EM observatories with time lags of about thirty minutes. A Monte Carlo simulation has been used to evaluate the low-latency GW pipeline's ability to reconstruct source positions correctly. Results. For signals near the detection threshold, our low-latency algorithms often localized simulated GW burst signals to tens of square degrees, while neutron star/neutron star inspirals and neutron star/black hole inspirals were localized to a few hundred square degrees. Localization precision improves for moderately stronger signals. The correct sky location of signals well above threshold and originating from nearby galaxies may be observed with 50% or better probability with a few pointings of wide-field telescopes.

  17. Constraints on the proton's gluon distribution from prompt photon production

    International Nuclear Information System (INIS)

    We analyze the capability of prompt photon production in pp and p anti p collisions to constrain the gluon distribution of the proton, considering data from fixed-target experiments as well as collider measurements. Combined fits are performed to these large-pT direct-γ cross sections and lepton-proton deep-inelastic scattering data in the framework of next-to-leading order perturbative QCD. Special attention is paid to theoretical uncertainties originating from the scale dependence of the results and from the fragmentation contribution to the prompt photon cross section. (orig.)

  18. Neutron reflectometry

    DEFF Research Database (Denmark)

    Klösgen-Buchkremer, Beate Maria

    2014-01-01

    Neutron (and X-ray) reflectometry constitute complementary interfacially sensitive techniques that open access to studying the structure within thin films of both soft and hard condensed matter. Film thickness starts oxide surfaces on bulk substrates, proceeding to (pauci-)molecular layers and up...... to hundreds of nanometers. Thickness resolution for flat surfaces is in the range of few Ǻngstrøm, and as a peculiar benefit, the presence and properties of buried interfaces are accessible. Focus here will be on neutron reflectometry, a technique that is unique in applications involving composite organic...... of new material. Understanding self-assembly of 2D-3D nanostructures at surfaces and the related interfaces in layered films is a precondition for the development of tailored tools with distributed functions, like new clothes (self-cleaning surfaces combined with mechanical resistance, low permeability...

  19. Neutronic designs and analyses of a new core-moderator assembly and neutron beam ports for the Penn State Breazeale Reactor

    International Nuclear Information System (INIS)

    A new core-moderator assembly and five new neutron beam ports are modeled and designed for the Penn State Breazeale Reactor (PSBR). The PSBR is an open pool, light water cooled, and moderated 1-MW research reactor with seven neutron beam ports. The existing core-moderator assembly design does not allow simultaneous utilization of all the available beam ports; only two beam ports, namely no.4 and no.7, are currently in use for research and education in the facility. Moreover, the prompt gamma-rays produced at the back side of the heavy water moderator tank shine into neutron beam tube no.4. Subsequently that is hampering the quality of the experimental data at the existing beam port facilities. The proposed design eliminates all the limitations of the existing design and provides multiple high-intensity and clean neutron beams to a new and expanded beam hall utilizing various instruments and techniques. The new design features a crescent-shaped moderator tank, which couples the reactor core to four thermal ports and one cold neutron beam port with three curved guide tubes for various cold neutron beam techniques. The modeling of the new PSBR design was achieved with highly detailed neutronics simulations using several stochastic simulation tools developed for the PSBR. The simulation results revealed the optimal design parameters and neutronics performance of the new beam ports, such that the thermal neutron beam intensity was significantly increased and the total prompt gamma dose was drastically decreased in the new beam port facilities. (author)

  20. Neutron scattering. Lectures

    International Nuclear Information System (INIS)

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