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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. Review of measurements of the average number of prompt fission neutrons

    International Nuclear Information System (INIS)

    The report summarises in tables and graphs data from measurements of the average number of prompt neutrons for spontaneous and neutron-induced fission carried out after 1972 and analyses some material contained in 116 references

  3. The energy dependence of the average number of prompt neutrons resulting from the neutron fission of U236

    International Nuclear Information System (INIS)

    The paper gives the numerical results of measurements of the average number of prompt neutrons per fission, #betta#-barsub(p), from neutron-induced fission of 236U in the 0.8 - 6.0 MeV range. An analysis of corrections and errors is given and a curve is recommended for #betta#-barsub(p) as a function of neutron energy. The estimated measurement accuracy is approximately 1%. (author)

  4. 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

  5. Calculation of prompt fission product average cross sections for neutron-induced fission of 235U and 239Pu

    International Nuclear Information System (INIS)

    Yield-weighted average cross sections of neutron radiative capture, (n,2n), and (n,3n) reactions over prompt fission products (FPs) from 235U and 239Pu are calculated. The prompt fission production yields are taken from the ENDF/B-VII.0 library. The FPs for each fissile material exist over a range of approximately 1000 neutron-rich nuclides. Several nuclear reaction codes are utilized for calculating the cross sections on each individual fission product - EMPIRE-2.19, TALYS-1.0, GNASH, and CoH. The influence of the FP isomers on the average cross sections is examined with TALYS. We investigate the dependence of the average cross sections on the number of FPs taken for averaging. It is shown that the average capture cross section is much more sensitive to the number of FPs included, compared with the (n,2n) and (n,3n) reactions. An intercomparison of the calculated cross sections with the different reaction codes is carried out. In the capture reaction, EMPIRE predicted lower cross section than TALYS and CoH owing to different default assumptions used in the γ-ray strength function modeling. Moreover, the pre-equilibrium models implemented in each code give different predictions for the neutron-emission reactions, although the differences are relatively small. We also discuss a difference between the macroscopic and microscopic calculation options in TALYS for the pre-equilibrium model, optical potential model, and γ-ray strength function. The predictive capability of the reaction codes for the capture reaction is examined by comparing their calculations with the ENDF data, which are based on measurements. Compared with the historic Foster and Arthur's evaluation, our new (n,2n) predictions are similar, although our capture predictions are almost an order of magnitude higher. Recommended cross sections for use in applications have been tabulated in ENDF-formatted files. (author)

  6. 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)

  7. 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%

  8. 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.

  9. 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

  10. 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

  11. Scission neutron emission and prompt fission neutron spectrum

    International Nuclear Information System (INIS)

    The mass, energy and angular integrated spectra of prompt fission neutrons for 235U induced fission in the energy range from thermal to 5 MeV were analyzed. It allows assume that about 0.362±0.025 neutrons per fission are emitted due to another mechanism then neutron emission from excited fragments after full acceleration. The spectrum of scission neutrons consists of two components with average energy 0.98 MeV and 2.74 MeV. The share of scission neutrons and their spectrum shape estimated in this work does not contradict to results of differential experiments analyzed in previous papers. (author)

  12. 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)

  13. 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

  14. Measurements of energy dependence of average number of prompt neutrons from neutron-induced fission of 235U, 241Am and 243Am from 0.5 to 12 MeV

    International Nuclear Information System (INIS)

    The energy dependence measurements results of average number of prompt neutrons from neutron-induced fission of 235U, 241Am, 243Am and total gamma-rays energy for 235U and 243Am from 0.5 to 12 MeV are presented. The measurements were carried out with neutron beam from uranium target of electron linac of All-Union Scientific Research Institute of Experimental Physics using time-of-flight technique on 28.5 m flight-path. The neutrons and gamma-rays from fission were detected by a big liquid scintillator detector (BLSD) loaded with gadolinium, events of fission - by parallel plate avalanche detector for fission fragments. Measurement of energy dependence of anti νp, Eγtot and determination of BLSD efficiency (relative to anti νp and Eγtot for 252Cf) were carried out simultaneously. Least squares fitting results give anti νp=3.05+0.14degEn for 241Am and anti νp=3.20+.15degEn for 243Am. (orig.)

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. Prompt fission neutron emission: Problems and challenges

    Directory of Open Access Journals (Sweden)

    Hambsch F.-J.

    2013-12-01

    Full Text Available This paper presents some of the challenges ahead of us even after 75 years of the discovery of the fission process and large progress made since then. The focus is on application orientation, which requires improved measurements on fission cross-sections and neutron and γ-ray multiplicities. Experimental possibilities have vastly improved the past decade leading to developments of highly sophisticated detector systems and the use of digital data acquisition and signal processing. The development of innovative fast nuclear reactor technology needs improved respective nuclear data. Advancements in theoretical modelling also require better experimental data. Theory has made progress in calculating fission fragment distributions (i.e. GEF code as well as prompt neutron and γ-ray emission to catch up with the improved experiments.

  20. 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.

  1. 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.

  2. 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

  3. Prompt neutron emission in nuclear fission

    International Nuclear Information System (INIS)

    Experimental results obtained in recent fragment-neutron correlation measurements are the basis for a detailed analysis of neutron emission characteristics in conjunction with several statistical-model approaches: (i) temperature distribution model (applied calculations), (ii) standard evaporation theory I (Weisskopf-Ewing approach extended by a rough angular momentum correction term), (iii) standard evaporation theory II (Hauser-Feshbach type calculations including angular momentum effects), (iv) statistical multistep compound theory (closed-form description including equilibrium as well as non-equilibrium emissions). All emission models account for an intricate fragment occurrence probability distribution in nucleon numbers, excitation energy, kinetic energy, and (except models (i) and (iv)) angular momentum. They have been used to predict yields, energy and angular distributions as well as representative c.m.s. spectrum shape parameters in the case of 252-Cf spontaneous fission in order to study the mechanisms of prompt fission neutron emission and several features of statistical emission. Model (iv) describes the development of the fragment compound system as a stochastic process starting at scission point and, hence, considering emission processes during fragment acceleration. The results of all model calculations indicate a clear predominance of the evaporation mechanism. The possible role of secondary mechanisms and difficulties in deducing information about them are discussed. The present paper gives a review on all four models. Results obtained within standard evaporation theory II (full-scale Hauser-Feshbach calculation) are discussed in more detail. (author). 27 refs, 4 figs

  4. 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.

  5. 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)

  6. A new approach to prompt fission neutron TOF data treatment

    Science.gov (United States)

    Zeynalov, Sh.; Zeynalova, O. V.; Hambsch, F.-J.; Oberstedt, S.

    The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics along with associated digital signal processing algorithms. A new mathematical approach, applicable to single events, was developed for prompt fission neutron (PFN) time-offlight distribution unfolding. The main goal was to understand the reasons of the long existing discrepancy between theoretical calculations and the measurements of prompt fission neutron (PFN) emission dependence on the total kinetic energy (TKE) of the fission fragments (FF). Since the 252Cf (sf) reaction is one of the main references for nuclear data the understanding of the PFN emission mechanism is very important both for nuclear fission theory and nuclear data. The experimental data were taken with a twin Frisch-grid ionization chamber and a NE213-equivalent neutron detector in an experimental setup similar to the well known work of C. Budtz-Jorgensen and H.-H. Knitter. About 2.5 × 105 coincidences between fission fragment (FF) and neutron detector response to prompt fission neutron detection have been registered (∼ 1.6 × 107 of total recorded fission events). Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12-bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. The main goal of this work was a detailed description of the prompt fission neutron treatment.

  7. 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.

  8. Similarities between calculated scission-neutron properties and experimental data on prompt fission neutrons

    Directory of Open Access Journals (Sweden)

    N. Carjan

    2015-07-01

    Full Text Available The main properties of the neutrons released during the neck rupture are calculated for U236 in the frame of a dynamical scission model: the angular distribution with respect to the fission axis (on spheres of radii R=30 and 40 fm and at time T=4×10−21 s, the distribution of the average neutron energies (for durations of the neck rupture ΔT=1 and 2×10−22 s and the total neutron multiplicity (for two values of the minimum neck-radius rmin=1.6 and 1.9 fm. They are compared with measurements of prompt fission neutrons during U235(nth,f. The experimental trends are qualitatively reproduced, i.e., the focusing of the neutrons along the fission axis, the preference of emission from the light fragment, the range, slope and average value of the neutron energy-spectrum and the average total neutron multiplicity.

  9. Cross correlation method application to prompt fission neutron investigation

    Science.gov (United States)

    Zeynalova, O. V.; Zeynalov, Sh.; Nazarenko, M. A.; Hambsch, F.-J.; Oberstedt, S.

    2012-10-01

    Do The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying cross correlation method and digital signal processing algorithms. A new mathematical approach for neutron/gamma pulse shape separation was developed and implemented for prompt fission neutron (PFN) time-of-flight measurement. The main goal was development of automated data analysis algorithms and procedures for data analysis with minimum human intervention. Experimental data was taken with a twin Frisch-grid ionization chamber and a NE213-equivalent neutron detector in an experimental setup similar to well work of C. Budtz-Jorgensen and H.-H. Knitter [1]. About 2*107 fission events were registered with 2*105 neutron/gamma detection in coincidence with fission fragments. Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12 bit waveform digitizer.

  10. Advanced Modeling of Prompt Fission Neutrons and Gamma Rays

    Directory of Open Access Journals (Sweden)

    Kawano T.

    2010-03-01

    Full Text Available 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.

  11. Advanced Modeling of Prompt Fission Neutrons and Gamma Rays

    OpenAIRE

    Kawano T; Talou P.

    2010-01-01

    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 yield...

  12. Multi - element determination by neutron - induced prompt gamma - ray analysis

    International Nuclear Information System (INIS)

    Prompt gamma neutron activation analysis ( PGNAA ) is an elemental and isotopic analytical technique in which prompt gamma - rays emitted within 10-14s after neutron capture reaction are measured. Although this analytical methodology is similar to instrumental neutron activation analysis (INAA), PGNAA is characterized by its capability for nondestructive multi - elemental analysis and by its ability to analyze elements that cannot be determined by INAA. In addition, due to the negligibly low residual radioactivity after being analyzed by PGNAA, the same sample can be used for other analytical methods. According to calculation, the analytical sensitivity of PGNAA is higher than that of INAA under the same neutron and gamma-ray measurement conditions. PGNAA technique is based on the interaction of the neutrons with the nuclei contained in a sample. Upon capturing a thermal neutron, a target nucleus gains energy which produces a compound nucleus in an excited state. This process may be represented as follows: AX + n → A+1 X * → A+1 X + γ, were A X is target and a+1 X are the target and compound nuclei, respectively. The compound nucleus is produced in excited state. The prompt gamma ray is emitted in the instantaneous decay of the compound nuclide. The neutron capture prompt gamma ray is usually emitted in less than 10-13 s. (author)

  13. Method for measuring prompt fission neutron energy spectrum by means of threshold activation detectors

    International Nuclear Information System (INIS)

    Prompt fission neutron energy spectrum as a function of energies of neutron inducing fission has been calculated on the basis of the Madland-Nix(MN) model. The resultant spectra have been weighted to excitation functions of 27Al(n,α), 32S(n,p) and 115In(n,n) threshold reactions in order to get the average cross sections and then spectral indices which are defined as the average cross section ratio for two selective threshold reactions among the above three. It is appeared that spectral indices together with the neutron spectra are varying with energies of neutron inducing fission. This may indicate that the prompt fission neutron energy spectrum can be determined by measuring experimentally the spectral index.(Author)

  14. Prompt Fission Neutron Emission in Resonance Fission of 239Pu

    Science.gov (United States)

    Hambsch, Franz-Josef; Varapai, Natallia; Zeinalov, Shakir; Oberstedt, Stephan; Serot, Olivier

    2005-05-01

    The prompt neutron emission probability from neutron-induced fission in the resonance region is being investigated at the time-of-flight facility GELINA of the IRMM. A double Frisch-gridded ionization chamber is used as a fission-fragment detector. For the data acquisition of both the fission-fragment signals as well as the neutron detector signals the fast digitization technique has been applied. For the neutron detection, large-volume liquid scintillation detectors from the DEMON collaboration are used. A specialized data analysis program taking advantage of the digital filtering technique has been developed to treat the acquired data. Neutron multiplicity investigations for actinides, especially in resonance neutron-induced fission, are rather scarce. They are, however, important for reactor control and safety issues as well as for understanding the basic physics of the fission process. Fission yield measurements on both 235U and 239Pu without prompt neutron emission coincidence have shown that fluctuation of the fission-fragment mass distribution exists from resonance to resonance, larger in the case of 235U. To possibly explain these observations, the question now is whether the prompt neutron multiplicity shows similar fluctuations with resonance energy.

  15. 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

  16. 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.

  17. Boron-10 prompt gamma analysis using a diffracted neutron beam

    International Nuclear Information System (INIS)

    A prompt gamma neutron activation analysis (PGNAA) facility has been built at the 5 MW MITR-II Research Reactor to support the ongoing boron neutron capture therapy (NCT) program. This facility is used to determine the concentration of B-10 in NCT relevant samples such as blood and urine. The B-10 concentration is needed to determine the radiation doses that tumor and healthy brain receive during neutron irradiation of a patient. Assaying for B-10 by PGNAA has several advantages over conventional chemical methods. It is rapid, accurate, nondestructive (allowing for re-analysis), inexpensive, sensitive (ppm level), generally independent of the chemical or physical matrix of the B-10, and does not require chemical manipulations of the sample. The authors goal was to build an inexpensive facility with a suitably high thermal neutron flux for PGNAA and a low level of photon and fast neutron contamination. Their design is unique in that it uses a diffracted beam. Most prompt gamma facilities use direct beams; these beams have a high thermal flux (> 107 n/cm2-sec), but are heavily contaminated with protons and fast neutrons. Other prompt gamma facilities use totally reflecting guide tubes; these beams have little contamination, but are expensive. The high thermal flux of direct beam facilities might not be an advantage since the detector usually must be moved further away from the sample to avoid high dead times in the multichannel analyzer

  18. 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)

  19. 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)

  20. Prompt fission neutron emission in resonance fission of 239Pu

    International Nuclear Information System (INIS)

    The prompt fission neutron emission probability was investigated at the time-of-flight facility GELINA at the IRMM. A double Frisch-gridded ionization chamber was used as a fission fragment detector. For the data acquisition of both fission fragment signals as well as the neutron detector signals the fast digitization technique has been applied. For the neutron detection large volume liquid scintillation detectors from the DEMON collaboration were used. A specialized data analysis program taking advantage of the digital filtering technique has been developed to treat the acquired data

  1. 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)

  2. 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)

  3. 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...

  4. Neutron beam characteristics of the prompt gamma neutron activation analysis system at HANARO

    International Nuclear Information System (INIS)

    Neutron beam characteristics of the Prompt Gamma Neutron Activation Analysis facility at HANARO were measured. The neutron beam of this facility is polychromatic thermal neutrons diffracted vertically by a set of pyrolytic graphite crystals at the Bragg angle of 45 .deg. from a horizontal beam line. Three conditions of thermal neutron extraction were applied by varying graphite crystal thickness and focusing geometry of diffracted beam. Thermal neutron profile, thermal neutron flux and Cd-ratio were measured at the sample position for each extraction condition. Thermal neutron flux of 6.1x107 n/cm2s and Cd-ratio of 364 are achieved finally

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. A New Method of Prompt Fission Neutron Energy Spectrum Unfolding

    Science.gov (United States)

    Zeynalova, O. V.; Zeynalov, Sh.; Hambsch, F.-J.; Oberstedt, S.

    2010-11-01

    The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics along with associated digital signal processing algorithms. The goal was to find out the reasons of a long time existing discrepancy between theoretical calculations and the measurements of prompt fission neutron (PFN) emission dependence on the total kinetic energy (TKE) of fission fragments (FF). On the one hand the 252Cf (sf) reaction is one of the main references for nuclear data, on the other hand the understanding of PFN emission mechanism is very important for nuclear fission theory. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213-equivalent neutron detector in total about 107 fission fragment-neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12 bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. For the first time the dependence of the number of emitted neutrons as a function of total kinetic energy (TKE) of the fragments is in very good agreement with theoretical calculations in the range of TKE from 140-220 MeV.

  10. Average neutron detection efficiency for DEMON detectors

    International Nuclear Information System (INIS)

    The neutron detection efficiency of a DEMON detector, averaged over the whole volume, was calculated using GEANT and applied to determine neutron multiplicities in an intermediate heavy ion reaction. When a neutron source is set at a distance of about 1 m from the front surface of the detector, the average efficiency, ϵav, is found to be significantly lower (20–30%) than the efficiency measured at the center of the detector, ϵ0. In the GEANT simulation the ratio R=ϵav/ϵ0 was calculated as a function of neutron energy. The experimental central efficiency multiplied by R was then used to determine the average efficiency. The results were applied to a study of the 64Zn+112Sn reaction at 40 A MeV which employed 16 DEMON detectors. The neutron multiplicity was extracted using a moving source fit. The derived multiplicities are compared well with those determined using the neutron ball in the NIMROD detector array in a separate experiment. Both are in good agreement with multiplicities predicted by a transport model calculation using an antisymmetric molecular dynamics (AMD) model code

  11. Impact of prompt-neutron corrections on final fission-fragment distributions

    Science.gov (United States)

    Al-Adili, A.; Hambsch, F.-J.; Pomp, S.; Oberstedt, S.

    2012-11-01

    Background: One important quantity in nuclear fission is the average number of prompt neutrons emitted from the fission fragments, the prompt neutron multiplicity, ν¯. The total number of prompt fission neutrons, ν¯tot, increases with increasing incident neutron energy. The prompt-neutron multiplicity is also a function of the fragment mass and the total kinetic energy of the fragmentation. Those data are only known in sufficient detail for a few thermal-neutron-induced fission reactions on, for example, 233,235U and 239Pu. The enthralling question has always been asked how the additional excitation energy is shared between the fission fragments. The answer to this question is important in the analysis of fission-fragment data taken with the double-energy technique. Although in the traditional approach the excess neutrons are distributed equally across the mass distribution, a few experiments showed that those neutrons are predominantly emitted by the heavy fragments.Purpose: We investigated the consequences of the ν(A,TKE,En) distribution on the fission fragment observables.Methods: Experimental data obtained for the 234U(n,f) reaction with a Twin Frisch Grid Ionization Chamber, were analyzed assuming two different methods for the neutron evaporation correction. The effect of the two different methods on the resulting fragment mass and energy distributions is studied.Results: We found that the preneutron mass distributions obtained via the double-energy technique become slightly more symmetric, and that the impact is larger for postneutron fission-fragment distributions. In the most severe cases, a relative yield change up to 20-30% was observed.Conclusions: We conclude that the choice of the prompt-neutron correction method has strong implications on the understanding and modeling of the fission process and encourages new experiments to measure fission fragments in coincidence with prompt fission neutrons. Even more, the correct determination of postneutron

  12. 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.

  13. 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.

  14. Monte Carlo simulation of prompt neutron emission during acceleration in fission

    International Nuclear Information System (INIS)

    The possibility of prompt neutron emission during acceleration of fission fragments (FFs) was examined by means of Monte Carlo method and statistical neutron emission model. Multimodal random neck-rapture model was used to describe the initial distribution of mass, charge, and total kinetic energy of the primary fragments. Statistical model was used to simulate the de-excitation process of the fragments from the moment of scission until full acceleration. By random number sampling, the fission process was simulated in order to obtain the basic physical quantities, and their correlations were analyzed to verify the adequacy of the model. It was found that, on the average, ∼10% and ∼16% of prompt neutrons for 235U(n th,f) and 252Cf(sf), respectively, were emitted before reaching 90% of the final fragment kinetic energy. (author)

  15. 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)

  16. 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

  17. Prompt Neutron Emission in 252CF Spontaneous Fission

    Science.gov (United States)

    Hambsch, F.-J.; Oberstedt, S.; Zeynalov, Sh.

    2011-10-01

    The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics. The goal was to compare the results from digital data acquisition and digital signal processing analysis with results of the pioneering work of Budtz-Jørgensen and Knitter. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213-equivalent neutron detector in total about 107 fission fragment-neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12 bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. The results are in very good agreement with literature. For the first time the dependence of the number of emitted neutrons as a function of total kinetic energy (TKE) of the fragments is in very good agreement with theoretical calculations in the range of TKE from 140-220 MeV.

  18. 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)

  19. Prompt gamma activation analysis using mobile reactor neutron beam

    International Nuclear Information System (INIS)

    Among the nuclear analytical methods that have proved very useful in biological and medical analyses is the in vivo prompt gamma neutron activation analysis (IVPGAA). In this work, an IVPGAA facility was assembled on a zero-power mobile nuclear reactor and has demonstrated its versatility for in vivo medical diagnosis. Absolute measurements of some environmental contaminants such as Cd, Hg, and Si in organs can be determined rapidly by partial body scan of IVPGAA, while assessment of vital constituents such as Ca, Cl, N, and P in either whole body or body part can be scanned by IVPGAA technique effectively. The in vivo clinical application using mobile reactor neutron beam are reviewed in detail. The IVPGAA scan provides unique insight into elemental concentration purpose. The IVPGAA scan can be performed on a regular basis without discomfort and radiation risk for patients. (author)

  20. DSP Algorithms for Fission Fragment and Prompt Fission Neutron Spectroscopy

    Science.gov (United States)

    Zeynalova, O.; Zeynalov, Sh.; Hambsch, F.-J.; Oberstedt, S.; Fabry, I.

    2009-10-01

    Digital signal processing (DSP) algorithms are in high demand for modern nuclear fission investigation due to importance of increase the accuracy of fissile nuclear data for new generation of nuclear power stations. DSP algorithms for fission fragment (FF) and prompt fission neutron (PFN) spectroscopy are described in the present work. The twin Frisch-grid ionization chamber (GTIC) is used to measure the kinetic energy-, mass- and angular distributions of the FF in the 252Cf(SF) reaction. Along with the neutron time-of-flight (TOF) measurement the correlation between neutron emission and FF mass and energy is investigated. The TOF is measured between common cathode of the GTIC and the neutron detector (ND) pulses. Waveform digitizers (WFD) having 12 bit amplitude resolution and 100 MHz sampling frequency are used for the detector pulse sampling. DSP algorithms are developed as recursive procedures to perform the signal processing, similar to those available in various nuclear electronics modules, such as constant fraction discriminator (CFD), pulse shape discriminator (PSD), peak-sensitive analogue-to-digital converter (pADC) and pulse shaping amplifier (PSA). To measure the angle between FF and the cathode plane normal to the GTIC a new algorithm is developed having advantage over the traditional analogue pulse processing schemes. Algorithms are tested by comparing the numerical simulation of the data analysis of the 252Cf(SF) reaction with data available from literature.

  1. 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)

  2. 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.

  3. RADSAT Benchmarks for Prompt Gamma Neutron Activation Analysis Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Burns, Kimberly A.; Gesh, Christopher J.

    2011-07-01

    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. High-resolution gamma-ray spectrometers are used in these applications to measure the spectrum of the emitted photon flux, which consists of both continuum and characteristic gamma rays with discrete energies. Monte Carlo transport is the most commonly used simulation tool for this type of problem, but computational times can be prohibitively long. This work explores the use of multi-group deterministic methods for the simulation of coupled neutron-photon problems. The main purpose of this work is to benchmark several problems modeled with RADSAT and MCNP to experimental data. Additionally, the cross section libraries for RADSAT are updated to include ENDF/B-VII cross sections. Preliminary findings show promising results when compared to MCNP and experimental data, but also areas where additional inquiry and testing are needed. The potential benefits and shortcomings of the multi-group-based approach are discussed in terms of accuracy and computational efficiency.

  4. Prompt neutron multiplicity in correlation with fragments from spontaneous fission of 252Cf

    Science.gov (United States)

    Göök, A.; Hambsch, F.-J.; Vidali, M.

    2014-12-01

    The spontaneous fission of 252Cf serves as an excellent benchmark of prompt emission in fission since experimental data can be obtained without the need of an incident beam. With the purpose of providing experimental data on the prompt fission neutron properties in correlation with fission-fragment characteristics, an experiment on 252Cf(SF) has been performed. In addition, the experiment serves as a benchmark of setup and analysis procedures for measurements of fluctuations in the prompt-neutron properties as a function of incident neutron energy in fission of the major actinides 235U and 239Pu. The experiment employs a twin Frisch grid ionization chamber as fission-fragment detector while neutrons were counted by using a liquid scintillator placed along the symmetry axis of the ionization chamber. Average neutron multiplicity has been obtained as a function of fission-fragment mass and total kinetic energy (TKE). The average multiplicity as a function of mass agrees well with available data in the literature in the mass range from 80 to 170 u. The existence of additional sawtooth structures in the far asymmetric mass region could not be confirmed, although the statistical accuracy of the present experiment is as good as the previous study where such structures have been reported [Nucl. Phys. A 490, 307 (1988)., 10.1016/0375-9474(88)90508-8]. The available data in the literature on the TKE dependence of the multiplicity show strong deviations. Therefore, effort was focused on investigating experimental factors in low-efficiency neutron-counting experiments that may lead to faulty determination of this dependence. Taking these factors into account, a result that agrees well with data from high-efficiency neutron-counting experiments is obtained. The experimental arrangement allows determination of the angle between the detected neutron and the fission axis, which permits the neutron properties to be transformed into the fission-fragment rest frame. Fission neutron

  5. 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

  6. 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)

  7. Effective delayed neutron fraction and prompt neutron lifetime of Tehran research reactor mixed-core

    International Nuclear Information System (INIS)

    Highlights: ► Kinetic parameters of Tehran research reactor mixed-core have been calculated. ► Burn-up effect on TRR kinetics parameters has been studied. ► Replacement of LEU-CFE with HEU-CFE in the TRR core has been investigated. ► Results of each mixed core were compared to the reference core. ► Calculation of kinetic parameters are necessary for reactivity and power excursion transient analysis. - Abstract: In this work, kinetic parameters of Tehran research reactor (TRR) mixed cores have been calculated. The mixed core configurations are made by replacement of the low enriched uranium control fuel elements with highly enriched uranium control fuel elements in the reference core. The MTRPC package, a nuclear reactor analysis tool, is used to perform the analysis. Simulations were carried out to compute effective delayed neutron fraction and prompt neutron lifetime. Calculation of kinetic parameters is necessary for reactivity and power excursion transient analysis. The results of this research show that effective delayed neutron fraction decreases and prompt neutron lifetime increases with the fuels burn-up. Also, by increasing the number of highly enriched uranium control fuel elements in the reference core, the prompt neutron lifetime increases, but effective delayed neutron fraction does not show any considerable change

  8. 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.)

  9. Design of a prompt gamma neutron activation analysis system and neutron beam characteristics at HANARO

    International Nuclear Information System (INIS)

    The design features and neutron beam characteristics are described for a prompt gamma neutron activation analysis(PGNAA) system at HANARO in Korea Atomic Energy Research Institute(KAERI). As a method to obtain clean beam of thermal neutrons, Bragg diffraction technique of using PG crystal is applied. The Bragg angle is set at 45 .deg. and the diffracted beam is a polychromatic one composed of neutrons from all diffraction orders n(≤n≤6). The fast neutron and gamma backgrounds will be low enough due to the use of diffracted beam and a tapered collimator. A neutron flux of 1.0x108 n/cm2sec is calculated at sample position by considering the reflectivity of PG crystal. The γ-ray detection system is comprised of a 30% n-type HPGe detector, signal electronics and a fast ADC. Construction of the beam line and setting up of the detection system is proceeding

  10. Numbers of prompt neutrons per fission for U233, U235, Pu239, and Cf252

    International Nuclear Information System (INIS)

    An absolute measurement of #-v#, the average number of prompt neutrons emitted per fission, is being made for the spontaneous fission of Cf262. The relative values of #-v# are being measured for neutron-induced fission of U233, U235, and Pu239, and are being compared with the spontaneous fission #-v# of Cf252. Neutrons with energies between thermal and 15 MeV are used. Particular emphasis is put on studying the dependence of #-v# on the incident neutron energy. A fission counter containing the appropriate isotope is placed in the centre of a large cadmium-loade d liquid scintillator. Through the fissionable isotope is passed a collimated beam of neutrons. Fission events, identified by pulses from the fission counter, open an electronic gate between the large liquid scintillator and a scaler. Scintillator pulses due to capture in the scintillating solution of thermalized fission neutrons are counted during the gate. The fission neutrons are detected almost independently of energy and with very high efficiency. With this technique values of #-v# to an accuracy of 1 % are expected. (author)

  11. 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

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

    OpenAIRE

    Göök Alf; Hambsch Franz-Josef; Oberstedt Stephan

    2016-01-01

    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 ...

  13. 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)

  14. 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.

  15. 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.

  16. 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)

  17. Consultants' meeting on prompt fission neutron spectra of major actinides. Summary report

    International Nuclear Information System (INIS)

    A Consultants' Meeting on 'Prompt Fission Neutron Spectra of Major Actinides' was held at IAEA Headquarters, Vienna, Austria, to discuss the adequacy and quality of the recommended prompt fission neutron spectra to be found in existing nuclear data applications libraries. These prompt fission neutron spectra were judged to be inadequate, and this problem has proved difficult to resolve by means of theoretical modelling. Major adjustments may be required to ensure the validity of such important data. There is a strong requirement for an international effort to explore and resolve these difficulties and recommend prompt fission neutron spectra and uncertainty covariance matrices for the actinides over the neutron energy range from thermal to 20 MeV. Participants also stressed that there would be a strong need for validation of the resulting data against integral critical assembly and dosimetry data. (author)

  18. 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)

  19. 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)

  20. Archaeometry Applications of Cold Neutron Based Prompt Gamma Neutron Activation Analysis. Chapter 9

    International Nuclear Information System (INIS)

    Prompt gamma activation analysis (PGAA) is based on the detection of prompt gamma radiation following the capture of neutrons into the atomic nucleus. Since every atomic nucleus emits characteristic prompt gamma radiation, this method is suitable for multielemental (panorama) analysis. The PGAA method can be regarded as absolutely non-destructive, because of the relatively low intensity of the beam. The main focus of this project was on the research of ancient ceramics. Pottery production was one of the most important crafts of prehistoric communities. As the first aim of this project, pottery findings from Neolithic and later prehistoric sites in Hungary were investigated with PGAA. Compositions of local sediments, as potential raw material sources, were compared with those of pottery. As the second aim of the project, pottery fragments from the multiperiod site at Voers, in south-west Hungary, were analysed, together with clay from the surrounding areas. In a firing experiment, an attempt to reproduce the ancient production techniques was made. As a third aim of the project, PGAA was tested from a methodological point of view. The reliability of the method has been occasionally checked through parallel measurements of archaeological samples with instrumental neutron activation analysis and X ray fluorescence analysis as well. The authors took part in a proficiency test, organized by the IAEA, on a porcelain material. (author)

  1. In vivo measurement of calcium by prompt-gamma neutron activation analysis

    International Nuclear Information System (INIS)

    This paper describes phantom experiments to assess the feasibility of measuring both part- and total-body calcium by the prompt - as opposed to the more usual delayed - neutron activation technique. The results indicate that a 30 min irradiation of a 20 cm length of the lumbar spine with a collimated beam of 252Cf neutrons, would yield approximately 2500 counts in the 6.420 MeV main and escape peaks, with a statistical precision of less than 5%, for a dose equivalent of 20 mSv. The proposed detection system, consisting of two 20% efficient germanium detectors positioned above the subject, i.e. on the side opposite the incident neutron beam, would provide improved uniformity of measurement compared with the usual situation where activation and counting are performed from the same side. The on-line technique also enables the subject to be scanned across the neutron beam to provide a measure of total-body calcium. In this case it would be possible to make an analysis to the same degree of precision for an average whole-body dose equivalent of only 1 to 1.3 mSv. 10 references, 3 figures, 1 table

  2. 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

  3. 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.

  4. Prompt gamma neutron activation analysis as an active interrogation technique for nuclear materials

    International Nuclear Information System (INIS)

    Prompt gamma neutron activation analysis (PGAA) is proposed as an instant, non-destructive method for the analysis of fissile materials and fission products. Measurements by PGAA were made on technetium and uranium compounds, the latter with various enrichments. Measurements were carried out in thermal and cold neutron beams at the Budapest Research Reactor. A beam chopper was used to collect the delayed decay gamma radiation from short lived nuclides separately. Accurate partial gamma ray production cross-sections were determined with internal standardization for a set of prompt and decay gamma rays following neutron capture in 235U, 238U and 99Tc and compared to those from the literature. In the case of 235U fission, prompt gamma lines were also applied.These cross-sections can be used for non-destructive analyses of uranium and technetium and also for the determination of the enrichment of uranium by prompt gamma activation analysis and neutron activation analysis. (author)

  5. Prompt neutron multiplicity in correlation with fragments from spontaneous fission of 252Cf

    OpenAIRE

    GÖÖK Alf; Hambsch, Franz-Josef; Vidali, Marzio

    2014-01-01

    The spontaneous fission of 252Cf serves as an excellent benchmark of prompt emission in fission since experimental data can be obtained without the need of an incident beam. With the purpose of providing experimental data on the prompt fission neutron properties in correlation with fission fragment characteristics an experiment on 252Cf(SF) has been performed. In addition, the experiment serves as benchmark of setup and analysis procedures for measurements of fluctuations in the prompt neutro...

  6. Prompt γ-ray data evaluation of thermal-neutron capture for A = 1-25

    International Nuclear Information System (INIS)

    The method of prompt γ-ray data evaluation for thermal-neutron capture has been briefly presented. The prompt capture γ-ray data of stable nuclei for A = 1 - 25 are evaluated. The evaluated data have been changed into the ENSDF format and the checks of physics and format have been made

  7. 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

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

    Science.gov (United States)

    Byun, S. H.; Choi, H. D.; Jun, B. J.; Kim, M. S.

    2000-07-01

    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° 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 1.0×108n/cm2s is expected at the sample position. Hence Bragg diffraction is a promising method of extracting thermal neutrons for PGNAA.

  9. 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

  10. Development Of A Digital Technique For The Determination Of Fission Fragments And Emitted Prompt Neutron Characteristics

    Science.gov (United States)

    Varapai, N.; Hambsch, F.-J.; Oberstedt, S.; Serot, O.; Barreau, G.; Kornilov, N.; Zeinalov, Sh.

    2005-11-01

    The present work demonstrates the application of the digital technique for nuclear measurements. This method has been implemented for measurements of promptly emitted fission neutrons in coincidence with fission fragments from 252Cf(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. The experimental set-up is installed at the Institute for Reference Materials and Measurements. Preliminary results are presented.

  11. 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...

  12. Comparative measurement of prompt fission γ -ray emission from fast-neutron-induced fission of 235U and 238U

    Science.gov (United States)

    Lebois, M.; Wilson, J. N.; Halipré, P.; Oberstedt, A.; Oberstedt, S.; Marini, P.; Schmitt, C.; Rose, S. J.; Siem, S.; Fallot, M.; Porta, A.; Zakari, A.-A.

    2015-09-01

    Prompt fission γ -ray (PFG) spectra have been measured in a recent experiment with the novel directional fast-neutron source LICORNE at the ALTO facility of the IPN Orsay. These first results from the facility involve the comparative measurement of prompt γ emission in fast-neutron-induced fission of 235U and 238U . Characteristics such as γ multiplicity and total and average radiation energy are determined in terms of ratios between the two systems. Additionally, the average photon energies were determined and compared with recent data on thermal-neutron-induced fission of 235U . PFG spectra are shown to be similar within the precision of the present measurement, suggesting that the extra incident energy does not significantly impact the energy released by prompt γ rays. The origins of some small differences, depending on either the incident energy or the target mass, are discussed. This study demonstrates the potential of the present approach, combining an innovative neutron source and new-generation detectors, for fundamental and applied research on fission in the near future.

  13. Facility at CIRUS reactor for thermal neutron induced prompt γ-ray spectroscopic studies

    Science.gov (United States)

    Biswas, D. C.; Danu, L. S.; Mukhopadhyay, S.; Kinage, L. A.; Prashanth, P. N.; Goswami, A.; Sahu, A. K.; Shaikh, A. M.; Chatterjee, A.; Choudhury, R. K.; Kailas, S.

    2013-03-01

    A facility for prompt γ-ray spectroscopic studies using thermal neutrons from a radial beam line of Canada India Research Utility Services (CIRUS) reactor, Bhabha Atomic Research Centre (BARC), has been developed. To carry out on-line spectroscopy experiments, two clover germanium detectors were used for the measurement of prompt γ rays. For the first time, the prompt γ-γ coincidence technique has been used to study the thermal neutron induced fission fragment spectroscopy (FFS) in 235U(nth, f). Using this facility, experiments have also been carried out for on-line γ-ray spectroscopic studies in 113Cd(nth, γ) reaction.

  14. Archaeometry Applications of Cold Neutron Based Prompt Gamma Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Prompt Gamma Activation Analysis (PGAA) is based on the detection of prompt gamma radiation following the capture of the neutrons into the atomic nucleus. Since every atomic nucleus emits characteristic prompt gamma radiation, this method is suitable for multielemental (panorama) analysis. The PGAA method can be regarded absolutely non-destructive, because of the relatively low intensity of the beam. In this project, we mainly focus on the research of ancient ceramics. Pottery production is one of the most important crafts of prehistoric communities. In the first task, pottery findings from Neolithic later prehistoric sites in Hungary were investigated with PGAA. Compositions of local sediments, as potential raw material sources were compared with those of pottery. In the second task, pottery fragments from the multiperiodical site of Voers, SW-Hungary were analyzed together with clay from the surrounding areas. In a firing experiment, an attempt to reproduce the ancient production techniques was done. As a third task of the project, PGAA was tested from methodological point of view. The reliability of the method has been occasionally checked through parallel measurements of archaeological samples with INAA and XRF as well. We took part in a proficiency test on a porcelane material, organized by IAEA. (author)

  15. 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.

  16. 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

  17. 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

  18. Use of prompt gamma emissions from polyethylene to estimate neutron ambient dose equivalent

    International Nuclear Information System (INIS)

    The possibility of using measured prompt gamma emissions from polyethylene to estimate neutron ambient dose equivalent is explored theoretically. Monte Carlo simulations have been carried out using the FLUKA code to calculate the response of a high density polyethylene cylinder to emit prompt gammas from interaction of neutrons with the nuclei of hydrogen and carbon present in polyethylene. The neutron energy dependent responses of hydrogen and carbon nuclei are combined appropriately to match the energy dependent neutron fluence to ambient dose equivalent conversion coefficients. The proposed method is tested initially with simulated spectra and then validated using experimental measurements with an Am–Be neutron source. Experimental measurements and theoretical simulations have established the feasibility of estimating neutron ambient dose equivalent using measured neutron induced prompt gammas emitted from polyethylene with an overestimation of neutron dose at very low energies. - Highlights: • A new method for estimating H⁎(10) using prompt gamma emissions from HDPE. • Linear combination of 2.2 MeV and 4.4 MeV gamma intensities approximates DCC (ICRP). • Feasibility of the method was established theoretically and experimentally. • The response of the present technique is very similar to that of the rem meters

  19. Use of prompt gamma emissions from polyethylene to estimate neutron ambient dose equivalent

    Energy Technology Data Exchange (ETDEWEB)

    Priyada, P.; Sarkar, P.K., E-mail: pradip.sarkar@manipal.edu

    2015-06-11

    The possibility of using measured prompt gamma emissions from polyethylene to estimate neutron ambient dose equivalent is explored theoretically. Monte Carlo simulations have been carried out using the FLUKA code to calculate the response of a high density polyethylene cylinder to emit prompt gammas from interaction of neutrons with the nuclei of hydrogen and carbon present in polyethylene. The neutron energy dependent responses of hydrogen and carbon nuclei are combined appropriately to match the energy dependent neutron fluence to ambient dose equivalent conversion coefficients. The proposed method is tested initially with simulated spectra and then validated using experimental measurements with an Am–Be neutron source. Experimental measurements and theoretical simulations have established the feasibility of estimating neutron ambient dose equivalent using measured neutron induced prompt gammas emitted from polyethylene with an overestimation of neutron dose at very low energies. - Highlights: • A new method for estimating H{sup ⁎}(10) using prompt gamma emissions from HDPE. • Linear combination of 2.2 MeV and 4.4 MeV gamma intensities approximates DCC (ICRP). • Feasibility of the method was established theoretically and experimentally. • The response of the present technique is very similar to that of the rem meters.

  20. Preliminary Results of a Full Hauser-feshbach Simulation of the Prompt Neutron and Gamma Emission from Fission Fragments

    Science.gov (United States)

    Regniera, D.; Litaizea, O.; Serota, O.

    The prompt neutron and gamma emission from fission fragments are investigated through the Monte Carlo code FIFRELIN which is developed at the CEA Cadarache research center. In a previous release of the code, the de-excitation of the fragments was treated in a two steps process. First the emission of all the prompt neutrons was simulated using a Weisskopf spectrum for the distribution of their kinetic energy. In a second step, the excitation energy still available was dissipated by the fragments as an electromagnetic decay cascade. This paper presents a new procedure for fragment de-excitation using an Hauser-Feshbach treatment of prompt particles emission. The neutron/gamma competition is then accounted for during the whole cascade. Moreover, the neutron emission is now ruled by the transmission coefficients directly coming from an optical model calculation performed with TALYS-1.4. The implementation of these models in the code FIFRELIN is quickly highlighted. The results in terms of neutrons and gamma multiplicities and spectra for one simulation of a 252Cf spontaneous fission are emphasized. The neutron multiplicity experimental data are used to constraint the parameters of our simulation. The prompt gamma spectrum calculated is then consistent with experimental data and the structures observed experimentally in the low energy range are well reproduced. However, the same simulation performed with several different nuclear models and parameters reveals high variation of these fission observables. For example, the average total gamma energy (Eγ,tot) is shown to vary up to 20% with changes in the level density or radiative strength function model.

  1. Prompt-Neutron Emission from U235 Fission Fragments

    International Nuclear Information System (INIS)

    A gadolinium-loaded large liquid scintillation counter is being used in conjunction with a neutron beam from the HERALD reactor at the Atomic Weapons Research Establishment, Aldermaston, to study neutron emission in the fission process. In particular, the neutron emission from individual fission fragments is observed. A fission-fragment detector comprising two gold-silicon suríace barrier counters operating in coincidence is situated at the edge of a 1-m-diam. spherical scintillation tank. The solid-state counters are placed on opposite sides of an evaporated fissile deposit on a thin nickel backing. A system of collimators selects for measurement only those fission events that have fragments travelling in the direction along the incident neutron beam and along the axis of the scintillator. Numbers of neutrons detected within 10 ps of a fission event are recorded. The angular correlation of neutron emission with fragment direction is used to associate the neutrons with the particular fission fragment that emitted them. Energies of both fragments are available from the solid-state counters, and identification of fragment mass and of the total kinetic energy of the fragment pair is made. The number of neutrons emitted by each fragment of the pair has been measured as a function of both the fragment mass and the total kinetic energy of the pair for thermal neutrons incident on U2'35. The usual asymmetry in the distribution of excitation energy between the heavy and light fragments is observed. The variation of the number of neutrons from the pair as a function of mass ratio is also determined. (author)

  2. 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

  3. Determination of average activating thermal neutron flux in bulk samples

    International Nuclear Information System (INIS)

    A previous method used for the determination of the average neutron flux within bulky samples has been applied for the measurements of hydrogen contents of different samples. An analytical function is given for the description of the correlation between the activity of Dy foils and the hydrogen concentrations. Results obtained by the activation and the thermal neutron reflection methods are compared

  4. 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)

  5. Prompt Fission Neutron Experiments on 235U(n,f) and 252Cf(SF)

    Science.gov (United States)

    Göök, A.; Hambsch, F.-J.; Oberstedt, S.; Vidali, M.

    For nuclear modeling and improved evaluation of nuclear data knowledge about fluctuations of the prompt neutron multiplicity as a function of incident neutron energy is requested for the major actinides 235U and 239Pu. Experimental investigations of the prompt fission neutron emission in resonance neutron induced fission on 235U are taking place at the GELINA facility of the IRMM. The experiment employs an array of neutron scintillation-detectors (SCINTIA) in conjunction with a newly designed 3D position sensitive twin Frisch-grid ionization chamber. A preparatory experiment on prompt fission neutron emission in 252Cf(SF) was undertaken to verify analysis procedures relevant for the implementation of the SCINTIA neutron detector array. The available literature data on the TKE dependence of the multiplicity show strong deviations. Therefore, effort was focused on investigating experimental factors in low efficiency neutron counting experiments that may lead to faulty determination of this dependence. Taking these factors into account a result that agree well with data from high efficiency neutron counting experiments is obtained.

  6. 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)

  7. 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.

  8. 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.

  9. Determination of protein content in grains by radioactive thermal neutron capture prompt gamma rays analysis

    International Nuclear Information System (INIS)

    The radioactive thermal neutron capture prompt gamma rays technique can be used to determinate the nitrogen content in grains without chemical destruction, with good precision and relative rapidity. This determination is based on the detection of prompt gamma rays emitted by the 14N(n,γ) 15N reaction product. The samples has been irradiated the tanGencial tube of the IEA-R1 research reator and a pair spectrometer has been used for the detection of the prompt gamma rays. The nitrogen content is determinated in several samples of soybean, commonbean, peas and rice, and the results is compared with typical nitrogen content for each grain. (Autor)

  10. 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)

  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. 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

  13. 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)

  14. Use of borated polyethylene to improve low energy response of a prompt gamma based neutron dosimeter

    Science.gov (United States)

    Priyada, P.; Ashwini, U.; Sarkar, P. K.

    2016-05-01

    The feasibility of using a combined sample of borated polyethylene and normal polyethylene to estimate neutron ambient dose equivalent from measured prompt gamma emissions is investigated theoretically to demonstrate improvements in low energy neutron dose response compared to only polyethylene. Monte Carlo simulations have been carried out using the FLUKA code to calculate the response of boron, hydrogen and carbon prompt gamma emissions to mono energetic neutrons. The weighted least square method is employed to arrive at the best linear combination of these responses that approximates the ICRP fluence to dose conversion coefficients well in the energy range of 10-8 MeV to 14 MeV. The configuration of the combined system is optimized through FLUKA simulations. The proposed method is validated theoretically with five different workplace neutron spectra with satisfactory outcome.

  15. 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.

  16. Description of peculiarities of prompt fission neutron spectrum in spontaneous fission of 252Cr

    International Nuclear Information System (INIS)

    Full text : 252Cf is the model object in theoretical and experimental studying of prompt fission neutron spectrum in the both spontaneous and induced fission of heavy nuclei. However, the form of spectrum observed has not been clearly understood especially in the region of lower and higher energies. The last compiled data are frequently used as a standart for the test of theoretical prescriptions of the neutron spectrum in spontaneous fission of 252Cf

  17. Contribution to the prompt fission neutron spectrum modeling. Uncertainty propagation on a vessel fluence calculation

    OpenAIRE

    Berge, Léonie

    2015-01-01

    The prompt fission neutron spectrum (PFNS) is very important for various nuclear physics applications. Yet, except for the 252Cf spontaneous fission spectrum which is an international standard and is used for metrology purposes, the PFNS is still poorly known for most of the fissionning nuclides. In particular, few measurements exist for the fast fission spectrum (induced by a neutron whose energy exceeds about 100 keV), and the international evaluations show strong discrepancies. There are a...

  18. 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)

  19. The calculation of prompt fission neutron spectrum for 233U(n,f) reaction by the semi-empirical method

    OpenAIRE

    Chen, Yong-Jing; Min, Jia; Liu, Ting-Jin; Shu, Neng-Chuan

    2013-01-01

    The prompt fission neutron spectra for neutron-induced fission of 233U for low energy neutrons (below 6 MeV) are calculated using the nuclear evaporation theory with a semi-empirical method, in which the partition of the total excitation energy between the fission fragments for the nth+233U fission reactions are determined with the available experimental and evaluation data. The calculated prompt fission neutron spectra agree well with the experimental data. The proportions of high- energy ou...

  20. 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).

  1. 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

  2. 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).

  3. Monte Carlo Simulation of Prompt Neutron Emission During Acceleration of Fission Fragments

    International Nuclear Information System (INIS)

    Possible reasons for apparent discrepancy in the prompt fission neutron spectra (PFNS) in the low-energy region, say <0.5 MeV, have been discussed. There are five possibilities: (1) uncertainty in the measured data in the low energy region, (2) neutron emission during acceleration (NEDA), instead of after full acceleration, (3) angular anisotropy in neutron emission in the CM-system of fission fragments (FF), (4) possible effect of 'yrast levels', and (5) possible existence of scission neutrons. In this report we examined the possibility (2) and (3) as well. It has been considered that the most of the prompt fission neutrons are emitted after full acceleration of fission fragments due to rapid acceleration by strong Coulomb repulsion working between them. On the other hand, however, there has also been a discussion on a possibility of neutron emission during acceleration. This phenomenon is interesting from physics point of view, as it provides knowledge on the timescale of de-excitation of excited nuclei and on possible competition with the Coulomb acceleration of FFs. It is also interesting from application point of view, since neutron emission from FFs before full acceleration implies an enhancement of low-energy component of the PFNS, because the NEDA neutrons receive smaller linear momentum from the FF. This possibility was examined by using Monte Carlo simulation

  4. 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...

  5. 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...

  6. 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)

  7. 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.

  8. 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)

  9. Establishment of prompt gamma neutron activation analysis facility at PARR-1

    International Nuclear Information System (INIS)

    Prompt gamma neutron activation analysis facility at through tube of upgraded PARR-1 reactor has been established. The salient features of the facility have been described. The in-pile as well as external collimators, beam shutter, target assembly and beam catcher were designed and fabricated indigenously. The flux at target position is 1.8x10/sup 10/ neutrons/cm/sup 2/sec and the cadmium ratio is about 10 Anti-Compton/pair spectrometer has been installed at 90 deg. to the incident beam. The measurements of the prompt gamma rays from thermal neutron capture in chlorine, nitrogen and chromium were carried out to calibrate HPGe detector up to 10 MeV. The set-up will be used in the determination of non-metals that form the elements of geological and biological materials or other trace elements with high thermal capture cross sections with improved peak/compton ratio of the spectrometer. (author)

  10. Prompt gamma neutron activation analysis in borehole logging and industrial process control

    International Nuclear Information System (INIS)

    Elemental analysis by prompt neutron activation analysis can be made by measuring the energy and intensity of prompt gamma-rays (PGNAA) emitted by an element upon capture of either a thermal or an epithermal neutron. Both prompt gamma-ray methods have a significant potential in bulk analysis because both neutrons and gamma-ray radiation are not significantly attenuated by the sample. The lack of absorption minimizes matrix effects and a large statistically meaningful sample is involved in the analysis. To accomplish the prompt neutron activation analysis in the laboratory it is relatively easy to design and control the entire process. The geometry of measurements is always constant and neutron flux at the sample can be measured. There is practically no restriction on size of detector or neutron source. However, in the narrow confines of a borehole there are a number of restrictions which must be considered. On-line analyses, although not restricted by space, have special problems in biological shielding, timing of detector pulses, need for rapid analysis and sensitivity for a given element. The purpose of this report is to discuss the different features which have to be taken into account when designing a PGNAA analyzer for a borehole logging tool or nuclear process control instrument. The performance characteristics of existing instruments, the special problems, possible solutions and the direction of the current thinking for future research are discussed. In addition, some appropriate applications where these instruments can be beneficially used to solve on-going problems are outlined. Refs, figs, tabs

  11. Current states for developing the prompt gamma neutron activation analysis system at HANARO

    International Nuclear Information System (INIS)

    Fabrication and performance test of major components used for the Prompt Gamma Neutron Activation Analysis system at HANARO have been completed. Thermal neutron extraction device consists of pyrolytic graphite crystals and a manual type two-axis goniometer. To focus neutron at the sample position graphite crystals can be tilted to concave mirror type. The tilting angle corresponding to the focusing condition was determined by reflecting parallel light. Collimator is composed of alternating layers of borated plastic, lead and polyethylene. As a shield surrounding collimator, heavy concrete mixed with B4C power was fabricated and neutron and gamma-ray shields for diffracted beam line have been completed. Presently, measurements of diffracted beam characteristics and neutron focusing effect are on the way with graphite crystals, collimator and surrounding shield installed

  12. The 3D tomographic image reconstruction software for prompt-gamma measurement of the boron neutron capture therapy

    International Nuclear Information System (INIS)

    A tomographic imaging system based on the spatial distribution measurement of the neutron capture reaction during Boron Neutron Capture Therapy (BNCT) would be very useful for clinical purpose. Using gamma-detectors in a 2D-panel, boron neutron capture and hydrogen neutron capture gamma-rays emitted by the neutron irradiated region can be detected, and an image of the neutron capture events can be reconstructed. A 3D reconstruction software package has been written to support the development of a 3D prompt-gamma tomographic system. The package consists of three independent modules: phantom generation, reconstruction and evaluation modules. The reconstruction modules are based on algebraic approach of the iterative reconstruction algorithm (ART), and on the maximum likelihood estimation method (ML-EM). In addition to that, two subsets of the ART, the simultaneous iterative reconstruction technique (SIRT) and the component averaging algorithms (CAV) have been included to the package employing parallel codes for multiprocessor architecture. All implemented algorithms use two different field functions for the reconstruction of the region. One is traditional voxel function, another is, so called, blob function, smooth spherically symmetric generalized Kaiser-Bessel function. The generation module provides the phantom and projections with background by tracing the prompt gamma-rays for a given scanner geometry. The evaluation module makes statistical comparisons between the generated and reconstructed images, and provides figure-of-merit (FOM) values for the applied reconstruction algorithms. The package has been written in C language and tested under Linux and Windows platforms. The simple graphical user interface (GUI) is used for command execution and visualization purposed. (author)

  13. Improved calculation of the prompt fission neutron spectrum from the spontaneous fission of 252Cf

    International Nuclear Information System (INIS)

    An improved calculation is presented for the prompt fission neutron spectrum N(E) from the spontaneous fission of 252Cf. 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, nuclear level density, 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. Particular attention will be given to the energy-dependent compound nucleus cross sections and to the nuclear level density model. Other refinements to the calculation of N(E) will also be discussed. Results will be presented and compared with earlier calculations of the spectrum and with recent experimental measurements of the spectrum. 9 figs

  14. 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.

  15. 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

  16. 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.)

  17. A method to measure prompt fission neutron spectrum using gamma multiplicity tagging

    Science.gov (United States)

    Blain, E.; Daskalakis, A.; Block, R. C.; Barry, D.; Danon, Y.

    2016-01-01

    In order to improve on current prompt fission neutron spectrum measurements, a gamma multiplicity tagging method was developed at the Rensselaer Polytechnic Institute Gearttner Linear Accelerator Center. This method involves using a coincidence requirement on an array of BaF2 gamma detectors to determine the timing of a fission event. This allows for much larger fission samples to be used due to the higher penetrability of gammas compared to fission fragments. Additionally, since the method relies on gammas as opposed to fission fragments, the effects of the low level discriminator, used in fission chambers to eliminate alpha events, are not seen. A 252Cf fission chamber was constructed in order to determine the viability of this method as well as the efficiency when compared to a fission chamber. The implemented multiple gamma tagging method was found to accurately reproduce the prompt fission neutron spectrum for the spontaneous fission of 252Cf and to detect 30% of fission events.

  18. 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

  19. Thermoelastic expansion in prompt-critical neutron pulse idealized in a fissile metallic sphere

    International Nuclear Information System (INIS)

    Prompt critical pulses in solid and homogeneous spheres of enriched uranium (93%) and metallic plutonium are studied. The feedback mechanism of the negative inserted reactivity is given by the elastic expansion due to the increase of the temperature in the sphere. Thermomechanical behavior and the capability of the system to become subcritical without a very large increase of energy released in the pulse are analysed. The neutronic and thermoelasticity equations are solved in the time. (M.C.K.)

  20. 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.

  1. 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)

  2. 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.

  3. 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

  4. The LANL/LLNL Program to Measure Prompt Fission Neutron Spectra at LANSCE

    Science.gov (United States)

    Haight, Robert; Wu, Ching Yen; Lee, Hye Young; Taddeucci, Terry; Mosby, Shea; O'Donnell, John; Fotiades, Nikolaos; Devlin, Mattew; Ullmann, John; Nelson, Ronald; Wender, Stephen; White, Morgan; Solomon, Clell; Neudecker, Denise; Talou, Patrick; Rising, Michael; Bucher, Brian; Buckner, Matthew; Henderson, Roger

    2015-10-01

    Accurate data on the spectrum of neutrons emitted in neutron-induced fission are needed for applications and for a better understanding of the fission process. At LANSCE we have made important progress in understanding systematic uncertainties and in obtaining data for 235U on the low-energy part of the prompt fission neutron spectra (PFNS), a particularly difficult region because down-scattered neutrons go in this direction. We use a double time-of-flight technique to determine energies of incoming and outgoing neutrons. With data acquisition via waveform digitizers, accidental coincidences between fission chamber and neutron detector are measured to high statistical accuracy and then subtracted from measured events. Monte Carlo simulations with high performance computers have proven to be essential in the design to minimize neutron scattering and in calculating detector response. Results from one of three approaches to analyzing the data will be presented. This work is funded by the US Department of Energy, National Nuclear Security Administration and Office of Nuclear Physics.

  5. 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.

  6. 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.

  7. 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

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

    Science.gov (United States)

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

    2002-07-01

    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°. 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 7.9×10 7 n/cm 2 s in a 1×1 cm 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,γ) reactions of N and Cl. Finally, the sensitivities and the detection limits were obtained for several elements.

  9. 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.

  10. The Effects of Nuclear Excitation of Prompt Fragments on the Independent Yields and Neutron Yields in Fission

    International Nuclear Information System (INIS)

    It has been found possible to account for the fine structure in the neutron yield versus mass distribution. The prediction is based on the assumption of a prompt independent curve obtained from the equal-charge-displacement (ECD) postulate and a linear dependence of fission-fragment excitation energy with mass. The method adopted for calculating neutron yields has been used to investigate the effect of neutron emission on independent yields. Independent yields after neutron emission have been calculated using ECD and a ''transition-state'' method to describe the prompt charge distribution. The calculated independent yields have been compared with some recent data. (author)

  11. 252Cf spontaneous prompt fission neutron spectrum measured at 0 degree and 180 degree relative to the fragment motion

    International Nuclear Information System (INIS)

    The 252Cf spontaneous prompt fission neutron spectrum at 0 degree and 180 degree relative to the motion direction of corresponding fission fragments was measured. High angular resolution for fragment measurements and high energy resolution for neutron measurements were obtained using multi-parameter TOF spectrometer. The results showed that there is a symmetric distribution of 'forward' and 'backward' for low energy in C.M.S. neutrons, which was an evidence of nonequilibrium neutrons existed in fission process

  12. Combination of the prompt neutron capture method with other neutron methods for substance elemental content analysis

    International Nuclear Information System (INIS)

    Neutron analysis method of determining element composition have found wide range of applications in industry thanks to different types of interaction of neutron with substances /1/. With the aim of widening the range of problems to be solved, on the basis of the device /2/ for determining the element content of substance, possibilities of combining the method based on the use of neutron capture gamma-ray spectrometry with other neutron methods, in particular neutron activation analysis and neutron absorption analysis were studied. In this radionuclide source (252Cf) with the yield of 1,5 x 107 neutron/sec is used. By means of using neutron capture gamma radiation spectrometry the possibilities of determining some elements (H, B, N, S etc. ), which are not determined by very widely used method, activation analysis. These elements can be determined by both the semiconductor and scintillation detectors with parameters fitting the manufacturing requirements. And for a number of elements ( B, Cl, Cd, Sm, Gd) very high limits of determination ( up to 10- 5 %) are possible using semiconductor Ge (Li) -detectors with high resolution. Possibility of determination of some 'well' activated elements ( K, Al, Fe, Mn, Ti, Sc etc.) in samples of ore and products of their processing using the neutron-activation analysis. For 1 hour of irradiation on the experimental device quite accurate analytical peak, of these elements are obtained, allowing to determine them qualitatively. However, with decreasing neutron yield of radionuclide source it becomes more difficult to achieve the necessary parameters both in neutron capture and activation analysis. Experimental works on determination of some elements with large cross-sections of capture ( B, Cd, Sm ) by absorption of neutrons in the investigated substance, i.e. using the neutron absorption analysis method with absence of other large capture cross section elements in the samples being studied. (author)

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. Explosives detection using prompt-gamma neutron activation and neural networks

    International Nuclear Information System (INIS)

    This work describes a study of the application of a neural network to determine the presence of explosives using the neutron capture prompt gamma-ray spectra of the substances as patterns which were simulated via Monte Carlo N-particle transport code, version 4B. After the training of the neural networks, it was possible to determine the presence of the C-4 explosive, even when they were occluded by several materials. The neural network was a powerful tool, able to recognize prompt gamma-ray explosive patterns in spite of the presence of occluding materials. Besides that, the network was able to generalize, identify the presence of explosive in cases in which it had not been trained. In that way, it was revealed as a potential tool for in situ inspection systems

  18. 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.

  19. PGAA-IAEA, Database for Prompt Gamma-ray Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Description of program or function: The Database for Prompt Gamma-ray Neutron Activation Analysis (PGAA) provides a variety of tables for all natural elements (from H to U) including the following data: isotopic composition, thermal radiative cross section (total and partial), Westcott g-factors, energy of the gamma rays (prompt and delayed), decay mode, half life and branching ratios. PGAA can be used in fields such as material science, geology, mining, archaeology, environment, food analysis and medicine. The PGAA is delivered with: - Database viewer for carrying out searches by isotope, energy and cross-section; - An isotope explorer 2.2 ENSDF viewer for displaying the level-scheme drawings and tables

  20. Prompt Neutron Decay Constant Determination Of Silicide Transition Core Using Noise Method

    International Nuclear Information System (INIS)

    Chairman of BATAN had decided to replace the Oxide fuel element type of RSG-GAS into silicide element type step by step. The replacement will create core transitions. Kinetic characteristic of the transition cores have to be monitored in order to know the deviation of core behavior. For that reason, the kinetic parameters have to be measured. Prompt neutron decay constant (alpha) is one of the kinetic parameters that has to be monitored continuously in the transition cores. In order not to disturb the normal operation of reactor, alpha parameter should be measured by using noise analysis method. The voltage of neutron flux at power of 15 MW is connected to preamplifier and filter then to the Dynamic Signal Analyzer Version-2 and then the auto power spectral density (APSD) was determined by using Fast Fourier transform. From the APSD curve of each channel of JKT03, the cut off frequency of each channel can be determined by using linear regression technique such that the prompt neutron decay constant can be estimated

  1. Statistical analysis for discrimination of prompt gamma ray peak induced by high energy neutron: Monte Carlo simulation study

    International Nuclear Information System (INIS)

    The purpose of this research is a statistical analysis for discrimination of prompt gamma ray peak induced by the 14.1 MeV neutron particles from spectra using Monte Carlo simulation. For the simulation, the information of 18 detector materials was used to simulate spectra by the neutron capture reaction. The discrimination of nine prompt gamma ray peaks from the simulation of each detector material was performed. We presented the several comparison indexes of energy resolution performance depending on the detector material using the simulation and statistics for the prompt gamma activation analysis. (author)

  2. Design of a prompt gamma neutron activation analysis system at HANARO

    International Nuclear Information System (INIS)

    The design feature is described for a prompt gamma neutron activation analysis (PGAA) system at HANARO, the 30 MW research reactor in Korea Atomic Energy Research Institute (KAERI). The primary purpose of this system is to analyze boron concentration in biological samples for research of neutron capture therapy. By considering the performance, available space and cost of setup, the PGAA system will use a thermal neutron beam diffracted by pyrolytic graphite (PG) in the existing ST1 horizontal beam line. The energy of monochromatic neutrons is 12.4 meV by setting the Bragg angle of 22.5 deg. The backgrounds will be low due to the use of diffracted beam and be further reduced through a Bi filter and a couple of LiF collimators. A neutron flux of 107 n/cm2sec is expected at sample position. The feature of low backgrounds will permit a closer detector position less than 10 cm from sample while the actual location will be decided upon test measurement. Capture γ-rays of 478 keV from 10B(n,α)7Li reaction will be detected by a 30% n-type HPGe detector and processed by a fast ADC. The goal of detection sensitivity for natural boron is 2,500 cps/mg. By completing the facility, efforts to improve the system performance will be further implemented in parallel with widening application of PGAA to other elements. (author)

  3. Prompt gamma ray activation analysis using neutron beam from THOR facility

    International Nuclear Information System (INIS)

    A reactor-based facility for neutron-capture prompt gamma-ray spectrometry for activation analysis has been installed at the one megawatt Tsing Hua Open-pool Reactor. The system consists a neutron beam port with collimators, irradiation stand, external beam tube, neutron beam dump, and counting system. The counting system consists of a 25 % n-type high purity germanium main gamma-ray detector, a 9'' x 10'' NaI(T1) anti-Compton detector shield, and Compton-suppressed electronics coupled to the CANBERRA S-88 Multi-parameter analyzer. Although the neutron beam at the sample irradiation station has an intensity of only 1,300,000 n/cm2s with a cadmium ratio of 26 : 1, the background levels of the on-line measurement in the mixed neutron/gamma field are sufficiently low, resulting a satisfactory detection of many elemental composition in samples. The lower limits of detection of 35 elements in sample matrix of the present system and the current applications are discussed. (author)

  4. 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

  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. Preliminary Remarks on Some Correlations of Prompt-Neutron Multiplicities with Properties of the Fission Fragments

    International Nuclear Information System (INIS)

    The differential behaviour of prompt-neutron multiplicities in the system 235U(nth,f) as a function of the total kinetic energy of the fission fragments and as a function of the emission angle relative to the direction of the light fragment are calculated with the GEF code. The results deviate from previous calculations by Nikolay Kornilov and are closer to the experimental data. The possible role of approximations and the neglect of correlations in the multi-dimensional coordinate space that characterizes the fission process are discussed. (author)

  7. Elemental compositional analysis of meteorites by Prompt Gamma-ray Neutron Activation Analysis (PGNAA)

    International Nuclear Information System (INIS)

    Prompt Gamma ray neutron activation analysis method (PGNAA) is an isotope specific non distractive nuclear analytical method for complete compositional analysis of materials. This technique is being used for determination of various elements such as H,B,Cd,Hg rare earths, alkali metals transition metals in various samples of antiques, geological, biological and meteorites. In this work PGNAA has been used to study three original meteorite samples Dhofar 020 (OMAN), Sikhote Alin (RUSSIA) and North West Africa 2909 (Africa) at Budapest, Hungary and the results are presented in this paper. (author)

  8. In situ characterization at limestone open pit mine using prompt gamma neutron activation

    International Nuclear Information System (INIS)

    Using prompt gamma neutron activation (PGNAA) in situ characterization of blast holes in Atocongo and Pucara open cut mines from Cementos Lima S.A. has been performed. This method collects information about the ore surrounding the bore hole and gives a real time and representative results for a geophysical model of the mine. The PGNAA system gives an in situ estimation of SiO2, Al2O3, Fe2O3, CaO, and SO3. The field trials have been proved that the system could be used to characterize the limestone open cut mines. (orig.)

  9. 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)

  10. 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)

  11. Coal stream composition analysis for process control using prompt neutron activation analysis

    International Nuclear Information System (INIS)

    In this paper we describe early results of a series of laboratory experiments and computer modeling studies designed to provide realistic accuracy limits for the determination of the elemental concentration in coal using prompt neutron activation analysis. The results provide guidance for optimizing the technique for monitoring the quality of coal which is being input to an electric power generating plant. The reported work was performed as the initial phase of an ongoing program to develop a prototype on-line coal analyzer based on the PNAA technique for power plant application

  12. Multielement analysis of foods by neutron capture prompt γ-ray activation analysis

    International Nuclear Information System (INIS)

    A method is described for the determination of H, B, Cl, K, Na, S, Ca, and Cd in foods using in-beam neutron capture prompt γ-ray activation analysis. Special calibration procedures were necessary because of matrix-related thermal neutron scattering-induced sensitivity and background enhancements. Detection limits and sensitivities are presented for best-case and worst-case irradiation conditions. The method was applied to multielement analysis of 41 foods and to B, Cl, and K analysis of 13 orange juice products in conjunction with analysis by inductively coupled plasma atomic emission spectrometry. The purpose of the latter application was to study B losses during acid digestion. (author) 9 refs.; 3 figs.; 2 tabs

  13. Contributions to the prompt neutron activation analysis of industrially used coals and zinc roasting products

    International Nuclear Information System (INIS)

    The construction of an irradiation plant for calibration measurement by means of prompt neutron activation analysis is described. A 5.84 μg and 16.3 μg Cf-252 source serve as neutron sources. Tests have shown an inner centred arrangement to offer the best solution for sources of this strength. The use of the PNAA method for determining sulphur, iron and chloride content in brown coal was tested and calibration curves drawn. The sulphur content of the coal briquettes tested was found to be 0.27% S, the iron content amounting to 0.21% Fe and chloride to 0.06%. These values correlate closely with values obtained from wet chemical industrial analysis. (WI)

  14. The Prompt Gamma Neutron Activation Analysis Facility at ICN—Pitesti

    Science.gov (United States)

    Bǎrbos, D.; Pǎunoiu, C.; Mladin, M.; Cosma, C.

    2008-08-01

    PGNAA is a very widely applicable technique for determining the presence and amount of many elements simultaneously in samples ranging in size from micrograms to many grams. PGNAA is characterized by its capability for nondestructive multi-elemental analysis and its ability to analyse elements that cannot be determined by INAA. By means of this PGNAA method we are able to increase the performace of INAA method. A facility has been developed at Institute for Nuclear Research—Piteşti so that the unique features of prompt gamma-ray neutron activation analysis can be used to measure trace and major elements in samples. The facility is linked at the radial neutron beam tube at ACPR-TRIGA reactor. During the PGNAA—facility is in use the ACPR reactor will be operated in steady-state mode at 250 KW maximum power. The facility consists of a radial beam-port, external sample position with shielding, and induced prompt gamma-ray counting system. Thermal neutron flux with energy lower than cadmium cut-off at the sample position was measured using thin gold foil is: φscd = 1.106 n/cm2/s with a cadmium ratio of:80. The gamma-ray detection system consist of an HpGe detector of 16% efficiency (detector model GC1518) with 1.85 keV resolution capability. The HpGe is mounted with its axis at 90° with respect to the incident neutron beam at distance about 200mm from the sample position. To establish the performance capabilities of the facility, irradiation of pure element or sample compound standards were performed to identify the gama-ray energies from each element and their count rates.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Do-Kun; Jung, Joo-Young; Suk Suh, Tae, E-mail: suhsanta@catholic.ac.kr [Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, Catholic University of Korea, Seoul 505 137-701 (Korea, Republic of); Jo Hong, Key [Molecular Imaging Program at Stanford (MIPS), Department of Radiology, Stanford University, 300 Pasteur Drive, Stanford, California 94305 (United States); Sil Lee, Keum [Department of Radiation Oncology, Stanford University School of Medicine, 875 Blake Wilbur Drive, Stanford, California 94305-5847 (United States)

    2015-01-15

    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.

  16. 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

  17. 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

  18. 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)

  19. 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

  20. 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

  1. 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.

  2. Correction for neutron self-shielding in large-sample prompt-gamma neutron activation analysis. Determination of macroscopic neutron cross sections

    International Nuclear Information System (INIS)

    When a sample is analysed with neutron activation analysis (NAA) neutron self-shielding and gamma self-absorption affect the accuracy. Both effects become even more important when the mass of a sample analysed is changed from small (say, 1 g) to large (say 30 kg). Therefore, corrections have to be carried out. Correction method for neutron self-shielding is considered for a thermal neutron beam irradiating large homogeneous samples for prompt-gamma NAA (PGNAA). The correction method depends on the macroscopic scattering and absorption cross sections of the sample. To avoid doing experiments with samples with different macroscopic scattering and absorption cross sections, the Monte Carlo model MCNP is applied in the development of the correction method. The computational development of the method to determine these cross sections through flux monitoring outside the sample is described. (author)

  3. Prompt Gamma Rays Emitted from Individual Fragments in Neutron-Induced Fission

    International Nuclear Information System (INIS)

    Prompt gamma rays associated with moving fission fragments of specific masses have been observed in thermal neutron-induced fission of 235U. The geometrical layout of the apparatus prevents detection of photons emitted from stopped fragments and determines the effective time resolution to about 1 ns after fission. Spectra are measured by means of a high-resolution Ge(Li) detector with 3.5% photopeak efficiency for 60Co. An 8'' ∅ x 9'' Nal(Tl) anti-Compton shield suppresses the Compton distribution in the spectra and the recording of events produced by fast fission neutrons. The coincident fission-fragment masses are deduced from their correlated kinetic energies as measured by two Si solid-state detectors. The observed Doppler shift in gamma ray energy allows the assignment of lines to single members of fragment pairs. Data are processed in a 256 x 256 x 2048 channel matrix. The main objective of these experiments is a study of the properties of individual neutron-rich nuclei far off the stability line. (author)

  4. Feasibility study of prompt gamma neutron activation for NDT measurement of moisture in stone and brick

    International Nuclear Information System (INIS)

    The conservation of stone and brick architecture or sculpture often involves damage caused by moisture. The feasibility of a NDT method based on prompt gamma neutron activation (PGNA) for measuring the element hydrogen as an indication of water is being evaluated. This includes systematic characterization of the lithology and physical properties of seven building stones and one brick type used in the buildings of the Smithsonian Institution in Washington, D.C. To determine the required dynamic range of the NDT method, moisture-related properties were measured by standard methods. Cold neutron PGNA was also used to determine chemically bound water (CBW) content. The CBW does not damage porous masonry, but creates an H background that defines the minimum level of detection of damaging moisture. The CBW was on the order of 0.5% for all the stones. This rules out the measurement of hygric processes in all of the stones and hydric processed for the stones with fine scale pore-size distributions The upper bound of moisture content, set by porosity through water immersion, was on the order of 5%. The dynamic range is about 10–20. The H count rates were roughly 1–3 cps. Taking into account differences in neutron energies and fluxes and sample volume between cold PGNA and a portable PGNA instrument, it appears that it is feasible to apply PGNA in the field

  5. 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

  6. 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

  7. 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.

  8. 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

  9. 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...

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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...

  19. FaNGaS - Fast Neutron Gamma Spectroscopy instrument for prompt gamma signature of inelastic scattering reactions

    OpenAIRE

    Rossbach, Matthias; Mauerhofer, Eric

    2015-01-01

    The FaNGaS instrument has been developed and constructed at the Forschungszentrum Jülich GmbH for investigation of neutron inelastic scattering reactions using the fission neutron beam SR10 at the Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II)  operated by the Technische Universität München in Garching. Prompt emitted gamma rays from excited states of irradiated elements can be used for analytical purposes.

  20. Improved Modeling of Prompt Fission Neutron Spectra for Nuclear Data Evaluations

    Science.gov (United States)

    Neudecker, Denise; Talou, Patrick; Kawano, Toshihiko; Kahler, Albert C.; White, Morgan C.

    2015-10-01

    The prompt fission neutron spectra (PFNS) of major actinides such as 239Pu and 235U are quantities of interest for nuclear physics application areas including reactor physics and national security. Nuclear data evaluations provide recommended data for those application areas based on nuclear theory and experiments. Here, we present improvements made to the effective models predicting the PFNS up to incident neutron energies of 30 MeV and their impact on evaluations. These models describe relevant physics processes better than those used for the current US nuclear data library ENDF/B-VII.1. In addition, the use of higher-fidelity models such as Monte Carlo Hauser-Feshbach calculations will be discussed in the context of future PFNS evaluations. (LA-UR-15-24763) This work was carried out under the auspices of the US Department of Energy, National Nuclear Security Administration and Office of Science, and performed by Los Alamos National Security LLC under Contract DE-AC52-06NA25396.

  1. 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

  2. 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 ...

  3. 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)

  4. Criticality experiments: analysis, evaluation, and programs. 8. Prompt Neutron Decay Constants in Uranium Diluted with Matrix Material Systems

    International Nuclear Information System (INIS)

    Rossi-Alpha measurements were performed on uranium diluted with matrix material systems to determine the prompt neutron decay constants. These constants represent an eigenvalue characteristic of these particular critical assemblies, which can be experimentally measured by the Rossi-Alpha or pulse neutron source techniques and calculated by a deterministic or Monte Carlo method. In the measurements presented in this paper, highly enriched foils diluted in various X/235U ratios with polyethylene and SiO2, and polyethylene and aluminum were assembled to a high multiplication, and the prompt neutron decay constants were obtained by the Rossi-Alpha technique. The uranium diluted with matrix material experiments were fueled with highly enriched uranium foils. The average dimensions of the bare foils were 22.86 cm squared and 0.00762 cm thick. The foils were laminated with plastic sheets to reduce the amount of airborne contamination. Each foil weighed ∼70 g. The diluent material consisted of SiO2, or 6061 aluminum plates, which were embedded into polyethylene plates. The SiO2 and aluminum plates were 22.86 cm square and 0.64 cm thick. The polyethylene plates were 39.12 cm square and 1.91 cm thick. Each polyethylene plate had a central recess whose dimensions were 22.86 cm by 22.86 cm by 0.64 cm deep and was used to accommodate the SiO2, or aluminum plates as well as the uranium foils. There were eight 39.12-cm-squared by 2.54-cm-thick high density polyethylene plates that form the top and bottom reflectors (four at the top and four at the bottom). Also, one of the polyethylene plates located in the center of the assembly had holes drilled in a radial direction to accommodate neutron detectors. Four 3He detectors were placed in this plate. The 3He detectors were 1.27 cm in diameter and ∼15 cm long. Rossi-Alpha measurements were performed at several subcritical separations for both experiments. The data were collected with a type I time analyzer (PATRM). This time

  5. Statistical analysis for discrimination of prompt gamma ray peak induced by high energy neutron: Monte Carlo simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Moo-Sub; Jung, Joo-Young; Suh, Tae Suk [College of Medicine, Catholic University of Korea, Seoul (Korea, Republic of)

    2015-05-15

    The purpose of this research was the statistical analysis for discrimination of the prompt gamma ray peak induced by the 14.1 MeV neutron particles from spectra using Monte Carlo simulation. For the simulation, the information of the eighteen detector materials was used to simulate spectra by the neutron capture reaction. To the best of our knowledge, the results in this study are the first reported data regarding the peak discrimination of high energy prompt gamma ray using the many cases (the eighteen detector materials and the nine prompt gamma ray peaks). The reliable data based on the Monte Carlo method and statistical method with the identical conditions was deducted. Our results are important data in the PGAA study for the peak detection within actual experiments.

  6. Statistical analysis for discrimination of prompt gamma ray peak induced by high energy neutron: Monte Carlo simulation study

    International Nuclear Information System (INIS)

    The purpose of this research was the statistical analysis for discrimination of the prompt gamma ray peak induced by the 14.1 MeV neutron particles from spectra using Monte Carlo simulation. For the simulation, the information of the eighteen detector materials was used to simulate spectra by the neutron capture reaction. To the best of our knowledge, the results in this study are the first reported data regarding the peak discrimination of high energy prompt gamma ray using the many cases (the eighteen detector materials and the nine prompt gamma ray peaks). The reliable data based on the Monte Carlo method and statistical method with the identical conditions was deducted. Our results are important data in the PGAA study for the peak detection within actual experiments

  7. Average neutron energy measurement at an accelerator facility, a practical health physics problem

    International Nuclear Information System (INIS)

    Surveys designed to estimate the average energy of neutrons escaping from shielded enclosures were made at the Clinton P. Anderson Meson Physics Facility (LAMPF). Information obtained from these data proved to be of value in establishing response factors for the personnel monitoring dosimeters (NTA film). The value of measuring average neutron energies was demonstrated about one year ago, when the monthly film badge report indicated significant neutron exposures to personnel of an experimental group at LAMPF. Neutron radiation-survey data, as well as recorded data from area monitoring stations, indicated much lower personnel neutron doses. Subsequent average neutron energy measurements, at the location of interest, revealed a well-defined region where average neutron energies were considerably greater than previously measured in other occupied areas of the accelerator facility. A discussion is given the rationale for the decision to alter for these experimenters the NTA film response factors from that normally applied to the LAMPF film badges

  8. 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

  9. 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

  10. 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.

  11. Neutron and gamma doses from medical in vivo prompt gamma-ray activation using a mobile nuclear reactor

    International Nuclear Information System (INIS)

    Medical diagnosis of toxic contaminants in body organs using in vivo neutron capture prompt gamma-ray activation technique has been investigated by several research groups. By using a high-resolution germanium detector coupled with fast electronics, characteristic prompt gamma rays emitted from neutron capture reactions with toxic cadmium, mercury, and silicon inside the human body are recorded in partial-body in vivo prompt gamma-ray activation analysis (PBIVPGAA) diagnosis. Although the radiation doses to the skin were reported in each and every previous PBIVPGAA work, organs and tissues sensitive to radiation, such as gonads, red bone marrow, bone surface, thyroid, breast, and lung are either the irradiated organ itself or are not far from the neutron beam. Both neutrons and gamma rays can scatter into the sensitive organ or tissue and interact with nuclei to cause radiation damage. The radiation safety and protection in PBIVPGAA diagnosis should focus on the radiation dose to sensitive organs and tissues, not to the skin. In this work the neutron facility identical to that used in previous works, the 0.1-W Tsing-Hua Mobile Educational Reactor (THMER) is used for PBIVPGAA diagnosis. A Lucite phantom was irradiated to simulate the investigation of toxic mercury and cadmium in kidneys and liver. The radiation risks of hereditary and somatic effects to irradiated patients were evaluated. Features of radiation doses and associated risks re discussed in this paper and compared to other medical diagnostic methods using nuclear techniques

  12. Prompt-gamma neutron activation analysis for the non-destructive characterization of radioactive wastes

    International Nuclear Information System (INIS)

    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 22nd 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

  13. 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

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

    International Nuclear Information System (INIS)

    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

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. Neutron capture prompt gamma-ray activation analysis of meat homogenates

    International Nuclear Information System (INIS)

    Thermal neutron capture prompt gamma-ray activation analysis (PGAA) was used to determine mass fractions of H, B, C, N, Na, Cl, K, and S in 2 meat homogenates. Twelve units of candidate Standard Reference Material (SRM) 1546 Meat Homogenate produced by the National Institute of Standards and Technology (NIST) were analyzed to provide NIST with certification data. This SRM is a realistic processed food matrix, ideal for food analysis programs such as the Food and Drug Administration's Total Diet Study. Another meat homogenate, Certified Reference Material LGC 7002 Pork/Chicken (along with NIST SRMs 1549 Non-fat Milk Powder and 1571 Orchard Leaves) was analyzed for quality control. Candidate SRM 1546 unit-to-unit heterogeneity was <2% for H, Na, Cl, and K, and 3.5% for N and within-unit heterogeneity was <2% for H, N, Cl, and K, and 2.9% for Na, similar to LGC 7002 homogeneity results. Control material mass fractions agreed well with certificate and consensus values. Protein mass fractions, calculated from N results, were 15.2% and 11.9% for candidate SRM 1546 and LGC 7002, respectively. Protein content calculated for SRM 1549 (36.0%) agreed well with known values for dried non-fat milk powder. (author)

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

    International Nuclear Information System (INIS)

    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

  1. 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

  2. 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

  3. 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.

  4. Cold neutron prompt gamma activation analysis, a non-destructive technique for hydrogen level assessment in zirconium alloys

    International Nuclear Information System (INIS)

    Highlights: ► Cold Neutron Prompt Gamma Activation Analysis has been performed to detect hydrogen in various Zr alloys. ► CNPGAA is non-destructive and can precisely detect low levels of hydrogen (as low as 5 wt ppm). ► Hydrogen pick-up fraction of ZIRLO samples has been investigated using CNPGAA and Vacuum hot Extraction. ► It is shown that the hydrogen pick-up fraction undergoes significant increase slightly before the weight gain transition. - Abstract: We propose a novel use of a non-destructive technique to quantitatively assess hydrogen concentration in zirconium alloys. The technique, called Cold Neutron Prompt Gamma Activation Analysis (CNPGAA), is based on measuring prompt gamma rays following the absorption of cold neutrons, and comparing the rate of detection of characteristic hydrogen gamma rays to that of gamma rays from matrix atoms. Because the emission is prompt, this method has to be performed in close proximity to a neutron source such as the one at the National Institute of Technology (NIST) Center for Neutron Research. Determination shown here to be simple and accurate, matching the results given by usual destructive techniques such as Vacuum Hot Extraction (VHE), with a precision of ±2 mg kg−1 (or wt ppm). Very low levels of hydrogen (as low as 5 mg kg−1 (wt ppm)) can be detected. Also, it is demonstrated that CNPGAA can be applied sequentially on an individual corrosion coupon during autoclave testing, to measure a gradually increasing hydrogen concentration. Thus, this technique can replace destructive techniques performed on “sister” samples thereby reducing experimental uncertainties.

  5. 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.

  6. The effect of high order harmonics on the prompt neutron decay constant in some complex SGHW type lattices

    International Nuclear Information System (INIS)

    A series of pulsed neutron source experiments have been carried out in SGHW lattices in the zero energy reactors DIMPLE and JUNO. These lattices were all multi-regional and included one lattice with a radial and one with an axial driver zone. It is shown that notwithstanding strong harmonic perturbation, a method of analysis is available which can isolate a fundamental mode prompt neutron decay constant from the decay data of the experiments, and that this is related to the reactivity of the lattice, and may be used, with limitations, to derive a reactivity - moderator height relationship. (author)

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

    International Nuclear Information System (INIS)

    The main discussions and conclusions from the Third Co-ordination Meeting on the Development of a Database for Prompt γ-ray Neutron Activation Analysis are summarised 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. (author)

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

    International Nuclear Information System (INIS)

    This report summarizes the presentations, recommendations and conclusions of the Second Research Co-ordination Meeting on Development of a Database for Prompt γ-ray Neutron Activation Analysis. The purpose of this meeting was to review results achieved on the development of the database, discuss further developments and planning of the products ol this CRP. Actions to be taken were agreed upon with the aim to complete the project by the end of 2002. (author)

  10. 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)

  11. Status of prompt gamma neutron activation analysis (PGAA) at TRR-1/M1 (Thai Research Reactor-1/Modified 1)

    International Nuclear Information System (INIS)

    The first prompt gamma activation analysis (PGAA) was designed, constructed and installed at a 6 inch diameter neutron beam port of the Thai Research Reactor-1/Modified 1 (TRR-1/M1) since 1989. Beam characteristic were made by Gd foil irradiation, X-ray film exposing and densitometry scanning consequently. The thermal neutron flux at sample position was measured by Au foil activation, and was about 1 x 107 n.cm2.sec-1 at 700 kW operating power. The experiments have been conducted successfully. In 1998, the PGAA facility has been developed for the reactor operating power at 1.2 MW. The new PGAA system, e.g., beam shutter, gamma collimator and biological shields have been designed to reduce the leakage of neutrons and gamma radiation to the acceptance levels in accordance with the International Commission on Radiation Protection Publication 60 (ICRP 60). The construction and installation will be completed in April 1999. (author)

  12. 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

  13. 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.

  14. 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

  15. 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

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

    Science.gov (United States)

    Sibczynski, P.; Kownacki, J.; Moszyński, M.; Iwanowska-Hanke, J.; Syntfeld-Każuch, A.; Gójska, A.; Gierlik, M.; Kaźmierczak, Ł.; Jakubowska, E.; Kędzierski, G.; Kujawiński, Ł.; Wojnarowicz, J.; Carrel, F.; Ledieu, M.; Lainé, F.

    2015-09-01

    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 epsilonBaF2 / epsilonEJ-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 epsilonBaF2 / epsilonEJ-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.

  17. Influence of orientation averaging on the anisotropy of thermal neutrons scattering on water molecules

    International Nuclear Information System (INIS)

    Determination of spatial distribution of neutron flux in water, most frequently used moderator in thermal reactors, demands microscopic scattering kernels dependence on cosine of thermal neutrons scattering angle when solving the Boltzmann equation. Since spatial orientation of water molecules influences this dependence it is necessary to perform orientation averaging or rotation-vibrational intermediate scattering function for water molecules. The calculations described in this paper and the obtained results showed that methods of orientation averaging do not influence the anisotropy of thermal neutrons scattering on water molecules, but do influence the inelastic scattering

  18. 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.

  19. Energies and Yields of Prompt Gamma Rays from Fragments in Slow-Neutron Induced Fission of 235U

    International Nuclear Information System (INIS)

    Measurements were made on the gamma radiation emitted from fission fragments in slow-neutron induced fission of 235U. The fragments were detected with solid state detectors of the surface barrier type and the gamma radiation with a Nal(Tl) scintillator. Mass selection was used so that the gamma radiation could be measured as a function of fragment mass. Time discrimination between the fission gammas and the prompt neutrons released in the fission process was employed to reduce the background. The gamma radiation emitted during different time intervals after the fission event was studied with the help of a collimator, the position of which was changed along the path of the fission fragments. In this way it was possible to select various collimator settings and let gamma radiation of different half-lives be enhanced. Gamma-ray energy spectra from these time components were then recorded as function of mass. The spectrum shape differed greatly depending on the half-life of the radiation and the fragment from which it was emitted. The results of the present measurements were discussed in the light of existing fission models, and comparisons were made with prompt gamma-ray and neutron data from other fission experiments

  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. 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.

  2. Measurement of (n,xn) reaction cross-sections using prompt γ spectroscopy at neutron beams with high instantaneous flux

    International Nuclear Information System (INIS)

    The work presented in this thesis is situated in the context of the GEDEON program of neutron cross-section measurements. This program is motivated by the perspectives recently opened by projects of nuclear waste treatment and energy production. There is an obvious lack of experimental data on (n,xn) reactions in the databases, especially in the case of very radioactive isotopes. An important technique to measure cross-sections of these reactions is the prompt γ-ray spectroscopy at white pulsed neutron beams with very high instantaneous flux. In this work, inelastic scattering and (n,xn) reactions cross-section measurements were performed on a lead sample from threshold to 20 MeV by prompt γ-ray spectroscopy at the white neutron beam generated by GELINA facility in Geel, Belgium. Digital methods were developed to treat HPGe CLOVER detector signals and separate γ-rays induced by the fastest neutrons from those belonging to the flash. Partial cross-sections for the production of several transitions in natural lead were measured and analyzed using theoretical calculations in order to separate the contributions of different reactions leading to the same residual isotope. Total cross-sections of the reactions in question were estimated. The results were compared to the TALYSS code theoretical calculations, as well as to other experimental results. This experiment has served to validate the method and it opens the way to measure (n,xn) reactions cross-sections with high instantaneous neutron flux on actinides, particularly the U233(n,2n) reaction which is important for the thorium cycle. (author)

  3. 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.

  4. 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

  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. The element composition determination of cement raw meal by neutron-induced prompt gamma-ray analysis

    International Nuclear Information System (INIS)

    Neutron-induced prompt gamma-ray analysis (NIPGA) is a new method which suit the modernization of cement industry. It can analyze several elements at the same time. The analysis of a kind of cement sample can be completed in 15 minutes, which is faster than conventional chemical analysis. The error of CaO, SiO2, Fe2O3 and Al2O3 of the cement by NIPGA comparing with the chemical analysis are less than 0.60%, 0.40%, 0.40% and 0.40%, respectively. (authors)

  7. 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

  8. Prompt Neutron Emission from Fragments in Spontaneous Fission of 244, 248Cm and 252Cf

    Science.gov (United States)

    Vorobyev, A. S.; Dushin, V. N.; Hambsch, F.-J.; Jakovlev, V. A.; Kalinin, V. A.; Laptev, A. B.; Petrov, B. F.; Shcherbakov, O. A.

    2005-11-01

    Neutrons emitted in fission were measured separately for each complementary fragment in correlation with fission fragment energies. Two high efficient Gd-loaded liquid scintillator tanks were used for neutron registration. Fission fragment energies were measured using a twin Frisch gridded ionization chamber with a pin-hole collimator. The neutron multiplicity distributions were obtained for each value of the fission fragment mass and energy and corrected for neutron registration efficiency, background and pile-up. The dependencies of these distributions on fragment mass and energy for different energy and mass bins, as well as the mass and energy distribution of the fission fragments are presented and discussed.

  9. Nuclear data and measurements series: Ratio of the prompt-fission-neutron spectrum of plutonium 239 to that of uranium 235

    International Nuclear Information System (INIS)

    The prompt-fission-neutron spectrum resulting from 239Pu fission induced by 0.55 MeV incident neutrons is measured from 1.0 to 10.0 MeV relative to that of 235U fission induced by the same incident-energy neutrons. The measurements employ the time-of-flight technique. Energy-dependent ratios of the two spectra are deduced from the measured values over the energy range 1.0 to 10.0 MeV. The experimentally-derived ratio results are compared with those calculated from ENDF/B-V, revision-2, and with results of recent microscopic measurements. Using the ENDF/B-V 235U Watt parameters for the 235U spectrum, the experimental measurements imply a ratio of average fission-spectrum energies of 239Pu/235U = 1.045 +- 0.003, compared to the value 1.046 calculated from ENDF/B-V, revision 2. 12 refs., 2 figs., 2 tabs

  10. The Prompt Gamma Neutron Activation Analysis Facility at the RA-6 reactor of the Bariloche Atomic Centre, Argentina

    International Nuclear Information System (INIS)

    The RA-6 is a research reactor with 500 kW of thermal power, located at the Bariloche Atomic Centre. In one of its five extraction tube facilities a prompt gamma neutron activation analysis system is now under construction. The neutron thermal flux in the position sample is 7 106 n/cm2s using a 5 cm thick bismuth filter. This work presents two facility designs, a preliminary one and another one with some improvements. Shielding optimizing experiences which justify the incorporated improvements are described. The applications of them allow the measurement of a borated sample. Also presented is a new design of the beam catcher and it is compared with the old one by MCNP modelling. New applications are being considered in the frame of the contract with the IAEA under the Co-ordinated Research Project (CRP) on 'New Applications of PGNAA'. (author)

  11. Prompt-gamma neutron activation analysis system design. Effects of D-T versus D-D neutron generator source selection

    International Nuclear Information System (INIS)

    Prompt-gamma neutron activation (PGNA) analysis is used for the non-invasive measurement of human body composition. Advancements in portable, compact neutron generator design have made those devices attractive as neutron sources. Two distinct generators are available: D-D with 2.5 MeV and D-T with 14.2 MeV neutrons. To compare the performance of these two units in our present PGNA system, we performed Monte Carlo simulations (MCNP-5; Los Alamos National Laboratory) evaluating the nitrogen reactions produced in tissue-equivalent phantoms and the effects of background interference on the gamma-detectors. Monte Carlo response curves showed increased gamma production per unit dose when using the D-D generator, suggesting that it is the more suitable choice for smaller sized subjects. The increased penetration by higher energy neutrons produced by the D-T generator supports its utility when examining larger, especially obese, subjects. A clinical PGNA analysis design incorporating both neutron generator options may be the best choice for a system required to measure a wide range of subject phenotypes. (author)

  12. 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,

  13. Library of prompt neutron and γ-emission spectra from fission fragments

    International Nuclear Information System (INIS)

    The statistical model of nuclear reactions is applied to describe the fission fragment neutron and gamma emission characteristics for spontaneous fission of 252Cf and for fission of 233,235U, 239Pu by thermal neutrons. The calculations of neutron and gamma-spectra are carried out for the fragments with A=70-160, excited up to 100 MeV. After testing of the model and input data library, calculations of neutron and γ-emission spectra for nuclei with A=70-170 excited up to 100 MeV were done to produce the Fission Fragments Emission Spectra Library (FFESL). FFESL contains the data of 1000 nuclei and will be used in calculations of neutron and γ-spectra for fission of heavy nuclei by intermediate energy nucleons. (author)

  14. New approximative orientation averaging of the water molecule interacting with the thermal neutron

    International Nuclear Information System (INIS)

    Orientation averaging is performed by exact orientation averaging (EOA→) and four approximate methods (two ell known and two new) and expression for the microscopic scattering kernel of thermal neutrons on water molecules are developed. Two well known approximate orientation averagings are Krieger-Nelkin's (KN) and Kappel-Young;s (KY). The results obtained by one pf the two newly proposed approximate orientation averaging methods agree best with the corresponding results obtained by EOA→. The biggest discrepancies between the EOA→ results and results of the approximate methods are obtained using well known KN approximate orientation averaging. (author)

  15. 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).

  16. Investigation of the prompt neutron emission mechanism in low energy fission of 235,233U(nth, f) and 252Cf(sf)

    OpenAIRE

    Val’ski G.V.; Gagarski A.M.; Shcherbakov O.A.; Vorobyev A.S.; Petrov G.A.

    2010-01-01

    A series of experiments has been performed to measure prompt neutron angular and energy distributions from thermal neutron-induced fission of 235,233U in correlation with the fission fragments. These distributions have been analyzed with the assumption of neutron isotropic emission from accelerated fission fragments. The performed analysis demonstrates that all obtained results can be described within 5% accuracy using this assumption. This discrepancy is approximately constant and doesn’t de...

  17. Monitoring the distribution of prompt gamma rays in boron neutron capture therapy using a multiple-scattering Compton camera: A Monte Carlo simulation study

    International Nuclear Information System (INIS)

    This study evaluated the use of Compton imaging technology to monitor prompt gamma rays emitted by 10B in boron neutron capture therapy (BNCT) applied to a computerized human phantom. The Monte Carlo method, including particle-tracking techniques, was used for simulation. The distribution of prompt gamma rays emitted by the phantom during irradiation with neutron beams is closely associated with the distribution of the boron in the phantom. Maximum likelihood expectation maximization (MLEM) method was applied to the information obtained from the detected prompt gamma rays to reconstruct the distribution of the tumor including the boron uptake regions (BURs). The reconstructed Compton images of the prompt gamma rays were combined with the cross-sectional images of the human phantom. Quantitative analysis of the intensity curves showed that all combined images matched the predetermined conditions of the simulation. The tumors including the BURs were distinguishable if they were more than 2 cm apart

  18. Monitoring the distribution of prompt gamma rays in boron neutron capture therapy using a multiple-scattering Compton camera: A Monte Carlo simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Taewoong; Lee, Hyounggun; Lee, Wonho, E-mail: wonhol@korea.ac.kr

    2015-10-21

    This study evaluated the use of Compton imaging technology to monitor prompt gamma rays emitted by {sup 10}B in boron neutron capture therapy (BNCT) applied to a computerized human phantom. The Monte Carlo method, including particle-tracking techniques, was used for simulation. The distribution of prompt gamma rays emitted by the phantom during irradiation with neutron beams is closely associated with the distribution of the boron in the phantom. Maximum likelihood expectation maximization (MLEM) method was applied to the information obtained from the detected prompt gamma rays to reconstruct the distribution of the tumor including the boron uptake regions (BURs). The reconstructed Compton images of the prompt gamma rays were combined with the cross-sectional images of the human phantom. Quantitative analysis of the intensity curves showed that all combined images matched the predetermined conditions of the simulation. The tumors including the BURs were distinguishable if they were more than 2 cm apart.

  19. Feasibility of using prompt neutron capture gamma rays to detect mercury

    International Nuclear Information System (INIS)

    This report describes a study to determine the feasibility to use neutrons to probe hidden spaces within buildings for the presence of mercury. The study was performed in four phases: First a search of the scientific literature was performed to ascertain the behavior of mercury subsequent to the capture of a thermal or near-thermal neutron. Second, a Monte Carlo investigation (using the code MCNP) of the effects of neutrons on materials expected to be found near and/or surrounding the mercury was undertaken. Third, a Monte Carlo study of the shielding and beam forming properties of various configurations of moderator material was started. Lastly, a Monte Carlo analysis of a likely field situation involving mercury behind 1 inch and 2 inch thicknesses of concrete was performed

  20. 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

  1. 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

  2. A mobile prompt-gamma in-vivo neutron activation facility

    International Nuclear Information System (INIS)

    A significant environmental-medical problem is the internal deposition of Cd in industrially exposed populations. With the development of 238Pu, Be neutron sources, it has become possible to design facilities that are significantly reduced in size and hence portable. The paper describes the development and fabrication of a self-contained 'neutron-capture' facility in a mobile trailer which is readily transportable. Although the initial project was designed for the measurement of Cd deposited in the liver and kidney of industrial workers, the sensitivity of the system will allow for measurements in normal populations. The limits of detection of Cd are 2.0 mg for kidney and 1.5 μg/g (wet weight) for liver (associated organ radiation dose is 660 mrem). The portable facility makes it possible to study Cd-exposed populations in any geographic location. With minor modifications of the collimator, detectors and counting geometry, it is also possible to make in-vivo measurements of total body nitrogen. The neutron source used in the mobile facility is 85 Ci 238Pu, Be shielded by epoxy resin doped with LiCO3 and 6LiF. Additional shielding is provided by Pb bricks and polyethylene bricks with 1% boron and 80% Pb. For Cd measurement, the detection system consists of two Ge(Li) detectors (25% efficiency each) shielded by Bi and a 1.5-cm layer of paraffin heavily doped with 6LiF. For body nitrogen, two shielded 15.2cmx15.2cm NaI(Tl) detectors are positioned above the scanning bed. This mobile activation facility could be usefully employed in countries which need to monitor industrial populations but do not have ready access to large neutron research facilities and permanently installed whole-body counters

  3. Average neutron cross section measurements in U-235 fission spectrum for some threshold reactions

    International Nuclear Information System (INIS)

    Fission neutron spectrum averaged cross sections have been measured for the threshold reactions 58Ni(n, 2n)57Ni, 127I(n, 2n)126I, 55Mn(n, 2n)54Mn, 63Cu(n, α)60Co and 31P(n, p)31Si, by the activation technique using high-resolution γ-ray spectrscopy. The fast neutron spectrum at the irradiation position has been characterized by using an additional set of activation foils. The results are presented with a complete uncertainty covariance matrix and are compared with evaluated values and previous measurements. (orig.)

  4. 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)

  5. Fission Mode Influence on Prompt Neutrons and γ-rays Emitted in the Reaction 239Pu(nth,f)

    Science.gov (United States)

    Serot, O.; Litaize, O.; Regnier, D.

    Recently, a Monte-Carlo code, which simulates the fission fragment de-excitation process, has been developed at CEA- Cadarache. Our aim is to get a tool capable to predict spectra and multiplicities of prompt particles (neutron and gamma) and to investigate possible correlations between fission observables. One of the main challenges is to define properly the share of the available excitation energy at scission between the two nascent fission fragments. Initially, after the full acceleration of the fission fragments, these excitation energies were treated within a Fermi-gas approximation in aT2 (where a and T stand for the level density parameter and the nuclear temperature) and a mass dependent law of the temperature ratio (RT=TL/TH, with TL and TH the temperature of the light and heavy fragment) has been proposed. With this RT-law, the main fission observables of the 252Cf(sf) could be reproduced. Here, in order to take into account the fission modes by which the fissioning nucleus undergoes to fission, we have adopted a specific RT-law for each fission mode. For actinides, the main fission modes are called Standard I, Standard II and Super Long (following Brosa's terminology). This new procedure has been applied in the case of the thermal neutron induced fission of 239Pu, reaction for which fission modes are rather well known.

  6. Application of Doppler broadening of neutron-induced prompt γ-rays to analytical sciences

    International Nuclear Information System (INIS)

    Activation analysis can measure γ-rays released from excited state of nucleus of nuclear reaction. The energy, sharp and width of γ-ray are not affected by the sample states. However, 7*Li from 10B(n,α)7*Li is an exception. It moderates by interaction with atoms in the course of motion and shows Doppler broadening, of which order depended on the chemical and physical state of sample. The principle of Doppler broadening is explained. The examples of spectra of Doppler broadening of 478 keV-prompt gamma ray are shown. The slowing down constant D (DLSS) of 7*Li is estimated by use of LSS (Lindhart, Scharff and Schiott) theory. As three application examples, boron in the natural cherry leaf, bean and yellow sand were characterized. The line shapes of green leaf and brown leaf were different. The former value was the same as the boric acid solution and the latter the solid boron. D value of yellow sand resembled the value estimated from the composition of aluminosilicate. Accordingly, boron is thought to be exchanged with aluminum. The future problems such as comparison D with DLSS, behavior of 7*Li generated from the smaller size sample with boron than the range and observation of other reaction are discussed. (S.Y.)

  7. Averaged U238 fission cross section measurement in Cf-252 neutron spectrum

    International Nuclear Information System (INIS)

    With regard to the standardization of Cf-252 neutron spectrum, the averaged U-238 fission cross section was measured over the Cf-252 neutron spectrum using foil activation technique. The gamma spectra of the fission products were obtained on a pure germanium detector at different decay times in order to identify the gamma rays of short, medium and long half-life radioisotopes. Analyzing the gamma spectra of the irradiated uranium foils several distinct photopeaks of several fission products were identified. The pure activity of Te-132 was determined from the net area under 228.2 kev photopeak after correcting it for neighbouring photopeaks of Np-239 and Pa-234. The averaged U238 fission cross section was calculated from the corrected counts of Te-132 photopeak to be 329±10 mb. The main sources of errors in the measurements are mainly due to inaccuracy of location of foils, neutron flux, counting statistics, weight of foils, impurity of foils and interference from neighbouring photopeaks. The contribution of fission neutrons from spontaneous fission of Cm-248, daughter of Cf-252, to the total flux density was estimated at 0.13%. (orig.)

  8. 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.

  9. 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

  10. Application of the Monte Carlo technique to the study of radiation transport in a prompt gamma in vivo neutron activation system

    International Nuclear Information System (INIS)

    A Monte Carlo code (MORSE-SGC) from the Radiation Shielding Information Centre at Oak Ridge National Laboratory, USA, has been adapted and used to model radiation transport in the Auckland prompt gamma in vivo neutron activation analysis facility. Preliminary results are presented for the slow neutron flux in an anthropomorphic phantom which are in broad agreement with those obtained by measurement via activation foils. Since experimental optimization is not logistically feasible and since theoretical optimization of neutron activation facilities has not previously been attempted, it is hoped that the Monte Carlo calculations can be used to provide a basis for improved system design

  11. A Study of the Mass Spectra of Fission Fragments after Prompt Neutron Emission

    International Nuclear Information System (INIS)

    The distribution of the masses of fission fragments, following neutron emission, was obtained by simultaneously measuring the velocity and energy of each particle. The special feature of this method is that it is essentially independent of the initial energy of the fragments, so that we were able to use relatively thick targets of fissionable material (0.1 mg/cm2). The energy measurement is made by a gold-silicon surface barrier detector: the velocity measurement was made on a flight path of 130 cm, with a total resolving power of 1.5 ns; The ''starting'' detector consisted of a windowless photomultiplier that detected directly the secondary electrons emitted by a thin metallic sheet during the passage of the fission fragments. The ''stop'' signal is picked up directly, by means of a transformer, on the semi-conductor detector. The results given in the paper relate to the thermal fission of U235, and are compared with the results obtained by the radiochemical method. (author)

  12. 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.)

  13. Yield of Prompt Gamma Radiation in Slow-Neutron Induced Fission of 235U a a Function of the Total Fragment Kinetic Energy

    International Nuclear Information System (INIS)

    Fission gamma radiation yields as functions of the total fragment kinetic energy were obtained for 235U thermal-neutron induced fission. The fragments were detected with silicon surface-barrier detectors and the gamma radiation with a Nal(Tl) scintillator. In some of the measurements mass selection was used so that the gamma radiation could also be measured as a function of fragment mass. Time discrimination between the fission gammas and the prompt neutrons released in the fission process was employed to reduce the background. The gamma radiation emitted during different time intervals after the fission event was studied with the help of a collimator, the position of which was changed along the path of the fission fragments. Fission-neutron and gamma-ray data of previous experiments were used for comparisons of the yields, and estimates were made of the variation of the prompt gamma-ray energy with the total fragment kinetic energy

  14. The prompt gamma neutron activation analysis facility at the RA-6 reactor of the Bariloche Atomic Center, Argentina

    International Nuclear Information System (INIS)

    The RA-6 is a pool type research reactor with high enrichment uranium fuel and 500 kW of nominal power. A Prompt Gamma Neutron Activation Analysis (PGNAA) facility is setting up at the radial beam tube no. 2. The development of this facility was motivated by the request of 10B analysis in the application of Boron Neutron Capture Therapy. New applications are being considered in the frame of the contract signed with IAEA under the CRP on 'New Applications of PGNAA'. The beam characteristics have been fully investigated both theoretically and experimentally. MCNP simulations were used to test different materials and geometries for each component of the facility. Gamma dose rate and neutron flux measurements were performed in order to validate the calculations and complete the design. The design goals were: To get a thermal neutron flux in the order of 107 n cm-2 s-1 at sample position; To reduce as much as possible the neutron and gamma background on the detection system and the surrounding areas; To achieve a detection limit of 1 mg of 10B. A schematic layout of the facility is shown. A bismuth filter is used to improve the neutron/gamma ratio of the free beam. The beam collimation is achieved by using two collimators: the first one is positioned 2 m downstream from the reactor core inside the biological shielding. This collimator consists of alternating rings of borated polyethylene and lead in order to absorb the neutrons and gamma rays. The inner diameter of each ring is gradually decreased. The last layer has an inner diameter of 6.8 cm. The total length of this collimator is 52.5 cm. A steel door situated just behind it isolates the beam tube allowing its flooding to shut the beam. The second collimator configures the beam size at the sample position. It is composed of alternating rings of lead and a mixture of lithium carbonate (66%wt) and paraffin. The last ring has an inner diameter of 40 mm. The beam shielding is completed by a massive box, situated around

  15. Neutron capture prompt gamma-ray analysis of stratospheric and groundfall ash following the Mt. St. Helens eruption of May 18, 1980

    International Nuclear Information System (INIS)

    Neutron-capture prompt γ-ray activation analysis (PGAA) is an exceptionally good method for the determination of the major and minor elements Na, Mg, Al, Si, K, Ca, Ti, Mn and Fe in most geological matrices. The trace elements H, B, S, Cl, Cd, Sm and Gd can often be readily measured in most geological materials. This technique was applied to volcanic ash samples collected in Washington and Montana by various groups following the May 18 eruption of the Mt. St. Helens volcano, as well as to several particulate samples collected at altitudes between 13 and 18 km by a NASA U-2 research aircraft. Groundfall ash samples show distinct elemental variations versus distance from the volcano. Samples collected sequentially at a given location also exhibit variations in the elemental ratios. These sequential samples were also subjected to leaching studies to determine soluble B, Cl and S. On the average, PGAA is able to account for 99.4+-1.7% of the mass of each sample. The PGAA results indicate that the sample from the greatest altitude resembles ashfall near the volcano, while those at lower altitudes somewhat resemble more distant ashfall. (author)

  16. 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.

  17. Measurements of prompt neutron multiplicity distributions in correlation with mass-energy distribution of fission fragments in spontaneous fission of 252Cf, 244Cm and 248Cm

    International Nuclear Information System (INIS)

    The number of prompt neutrons emitted in the fission event have been measured separately for each complementary fragment in coincidence with fragment mass and kinetic energies in spontaneous fission of 252Cf, 244Cm and 248Cm. Two high efficient Gd-loaded liquid scintillator tanks were used for the neutron registration. Approximately 3x106 fission events coincident with prompt neutron emission have been accumulated for each isotope. The mean neutron multiplicity, the dispersion and the covariance of the multiplicity distributions have been obtained as a function of fission fragment mass and kinetic energy. The neutron multiplicity data have been corrected for neutron registration efficiency, background and pile-up. Dependencies of the moments of the multiplicity distributions on the fragment mass and total kinetic energy for different mass bins, as well as mass and total kinetic energy distributions of the fission fragments are presented, discussed and compared for the different isotopes investigated. The results showed a different behavior of the moments of the multiplicity distribution depending on the fragment mass asymmetry that reflects changes in the dynamical effects for different fission modes. (author)

  18. 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

  19. Investigation of the prompt neutron emission mechanism in low energy fission of 235,233U(nth, f and 252Cf(sf

    Directory of Open Access Journals (Sweden)

    Val’ski G.V.

    2010-10-01

    Full Text Available A series of experiments has been performed to measure prompt neutron angular and energy distributions from thermal neutron-induced fission of 235,233U in correlation with the fission fragments. These distributions have been analyzed with the assumption of neutron isotropic emission from accelerated fission fragments. The performed analysis demonstrates that all obtained results can be described within 5% accuracy using this assumption. This discrepancy is approximately constant and doesn’t depend on fragment mass and the total kinetic energy (TKE. Some minor peculiarities of angular distribution may be interpreted as a result of anisotropy of the fission neutron angular distribution in the fragment center-of-mass system.

  20. The Design of a Prompt Gamma Neutron Activation Analysis Beam for BNCT Purpose at the TRIGA Mark II Reactor in Pavia

    Energy Technology Data Exchange (ETDEWEB)

    Stella, S.; Bazani, A.; Ballarini, F.; Bortolussi, S.; Protti, N.; Altieri, S. [Department of Nuclear and Theoretical Physics, University of Pavia (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Section of Pavia (Italy); Bruschi, P. [Department of Nuclear and Theoretical Physics, University of Pavia (Italy)

    2011-07-01

    In preclinical and clinical Boron Neutron Capture Therapy studies the knowledge of the amount of {sup 10}B in blood and tissues is very important. The boron concentration measurements method used in Pavia (Italy) is based on the charged particles spectrometry of thin tissue cuts irradiated in the Thermal Column of the TRIGA reactor of the University. In order to perform measurements in biological liquids such as blood and urine, or in other tissue that cannot be cut in slices, a Prompt Gamma Neutron Activation Analysis (PGNAA) facility is being designed, which measures {sup 10}B concentration detecting the prompt gamma from boron nuclear capture reaction. At the TRIGA reactor in Pavia, there are four horizontal channels, potentially available for PGNAA. The choice of the suitable channel, and the design of its configuration, were achieved using the Monte Carlo neutron transport code MCNP4c2. To perform the simulations, an input code already validated, describing the reactor structure and the neutron source, was used. The calculations were implemented applying non-analog techniques for the neutron transport, that are necessary to obtain a sufficient statistic in every positions along the channel and especially at its end. The selection of the channel for PGNAA installation was carried out by comparing the simulated fluxes obtained in the different channels at the present configuration. The channel shielded by the core reflector was chosen, because the graphite lowers the fast component of the neutrons, with no need to insert additional material in the facility. The thermal flux at its end is 1.7 x 10{sup 8} n/cm{sup 2} s with thermal-to-total neutron flux ratio around 0.8. Subsequently a bismuth block for gamma radiation shielding and blocks of single crystal sapphire as filter for fast neutron component were inserted in the channel. Other components of the facility that are under study are a collimator and the beam catcher. (author)

  1. Evaluation of the {sup 239}Pu prompt fission neutron spectrum induced by neutrons of 500 keV and associated covariances

    Energy Technology Data Exchange (ETDEWEB)

    Neudecker, D., E-mail: dneudecker@lanl.gov [Theoretical Division, Los Alamos National Laboratory, P.O. Box 1663, MS-B283, NM 87545 (United States); Talou, P., E-mail: talou@lanl.gov [Theoretical Division, Los Alamos National Laboratory, P.O. Box 1663, MS-B283, NM 87545 (United States); Kawano, T., E-mail: kawano@lanl.gov [Theoretical Division, Los Alamos National Laboratory, P.O. Box 1663, MS-B283, NM 87545 (United States); Smith, D.L., E-mail: donaldlarnedsmith@gmail.com [Nuclear Engineering Division, Argonne National Laboratory, 1710 Avenida del Mundo #1506, Coronado, CA 92118 (United States); Capote, R., E-mail: r.capotenoy@iaea.org [Nuclear Data Section, International Atomic Energy Agency Vienna, Vienna International Centre, P.O. Box 100, A-1400 Vienna (Austria); Rising, M.E., E-mail: mrising@lanl.gov [X-Division, Los Alamos National Laboratory, P.O. Box 1663, MS-F663, NM 87545 (United States); Kahler, A.C., E-mail: akahler@lanl.gov [Theoretical Division, Los Alamos National Laboratory, P.O. Box 1663, MS-B283, NM 87545 (United States)

    2015-08-11

    We present evaluations of the prompt fission neutron spectrum (PFNS) of {sup 239}Pu induced by 500 keV neutrons, and associated covariances. In a previous evaluation by Talou et al. (2010), surprisingly low evaluated uncertainties were obtained, partly due to simplifying assumptions in the quantification of uncertainties from experiment and model. Therefore, special emphasis is placed here on a thorough uncertainty quantification of experimental data and of the Los Alamos model predicted values entering the evaluation. In addition, the Los Alamos model was extended and an evaluation technique was employed that takes into account the qualitative differences between normalized model predicted values and experimental shape data. These improvements lead to changes in the evaluated PFNS and overall larger evaluated uncertainties than in the previous work. However, these evaluated uncertainties are still smaller than those obtained in a statistical analysis using experimental information only, due to strong model correlations. Hence, suggestions to estimate model defect uncertainties are presented, which lead to more reasonable evaluated uncertainties. The calculated k{sub eff} of selected criticality benchmarks obtained with these new evaluations agree with each other within their uncertainties despite the different approaches to estimate model defect uncertainties. The k{sub eff} one standard deviations overlap with some of those obtained using ENDF/B-VII.1, albeit their mean values are further away from unity. Spectral indexes for the Jezebel critical assembly calculated with the newly evaluated PFNS agree with the experimental data for selected (n,γ) and (n,f) reactions, and show improvements for high-energy threshold (n,2n) reactions compared to ENDF/B-VII.1.

  2. 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.

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

    International Nuclear Information System (INIS)

    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 ∼ 300 ppm to ∼ 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 ∼ 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

  4. 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

  5. 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.

  6. Development of a prompt-gamma neutron activation analysis facility for small animal in vivo body composition studies using Am-Be Source

    International Nuclear Information System (INIS)

    Full text: The design, calibration, radiation dosimetry and preliminary performance evaluation of a prompt-gamma neutron activation analysis facility for in vivo body composition studies in small animals (i.e. rats or rabbits) are described. The system design was guided by Monte Carlo neutron and photon transport calculations performed using the MCNP-4C code. The facility utilizes a 555 GBq (15 Ci) Am-Be radionuclide neutron source positioned within a graphite collimator and appropriate shielding assembly. Prompt gamma rays produced by thermal neutron capture reactions within the animal are detected by a combination of a NaI(Tl) and a HPGe detectors positioned on either side of the sample, perpendicularly to the neutron beam. Small animal body nitrogen and hydrogen are determined by the NaI(Tl) detector by analysis of the 10.83 MeV and 2.22 MeV peaks, respectively, while calcium and chlorine are determined by the HPGe detector by analysis of the 6.42 MeV and 6.11 MeV peaks, respectively. Moreover, body potassium is determined independently by means of 40K measurement at a modified whole body counter facility. Appropriate corrections for animal body size and shape are applied. Mixed neutron and gamma radiation dosimetry was performed using a tissue-equivalent proportional counter. The facility described is a simple tool enabling us to perform in vivo analysis of the major body compartments of protein, bone mass, extra-cellular and intra-cellular space. It will be used to perform serial nutritional and metabolic studies in sets of small experimental animals under controlled conditions for an ethically accepted radiation dose and without the need to kill the animal. (author)

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

    International Nuclear Information System (INIS)

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

  8. 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.

  9. 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.

  10. Determination of boron in ceramic reference materials by prompt gamma activation analysis using focused neutron guided beam of JRR-3M

    International Nuclear Information System (INIS)

    Prompt gamma activation analysis using a focused thermal neutron guided beam at JAEA JRR-3M was applied to the determination of B in ceramic certified reference materials (BAM CRM S-003 Silicon Carbide Powder and NMIJ CRM 8004-a Silicon Nitride Powder). Cl and Si were used as internal standards to obtain linear calibration curves of B. The analytical result of B in BAM CRM S-003 was in good agreement with the certified value. The relative expanded measurement uncertainties (k = 2) were 4.8% for BAM CRM S-003 and 4.9% for NMIJ CRM 8004-a. (author)

  11. 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...

  12. Distribution of Prompt Neutron Emission Probability for Fission Fragments in Spontaneous Fission of 252Cf and 244,248Cm

    Science.gov (United States)

    Vorobyev, A. S.; Dushin, V. N.; Hambsch, F.-J.; Jakovlev, V. A.; Kalinin, V. A.; Laptev, A. B.; Petrov, B. F.; Shcherbakov, O. A.

    2005-05-01

    Neutrons emitted in fission events were measured separately for each complementary fragment in correlation with fission fragment energies. Two high-efficiency Gd-loaded liquid scintillator tanks were used for neutron registration. Fission fragment energies were measured using a twin Frisch gridded ionization chamber with a pinhole collimator. The neutron multiplicity distributions were obtained for each value of the fission fragment mass and energy and corrected for neutron registration efficiency, background, and pile-up. The dependency of these distributions on fragment mass and energy for different energy and mass bins as well as mass and energy distribution of fission fragments are presented and discussed.

  13. 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

  14. 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.)

  15. 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.)

  16. 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

  17. Standard Test Method for Measuring Neutron Fluence and Average Energy from 3H(d,n)4He Neutron Generators by Radioactivation Techniques 1

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method covers a general procedure for the measurement of the fast-neutron fluence rate produced by neutron generators utilizing the 3H(d,n)4He reaction. Neutrons so produced are usually referred to as 14-MeV neutrons, but range in energy depending on a number of factors. This test method does not adequately cover fusion sources where the velocity of the plasma may be an important consideration. 1.2 This test method uses threshold activation reactions to determine the average energy of the neutrons and the neutron fluence at that energy. At least three activities, chosen from an appropriate set of dosimetry reactions, are required to characterize the average energy and fluence. The required activities are typically measured by gamma ray spectroscopy. 1.3 The measurement of reaction products in their metastable states is not covered. If the metastable state decays to the ground state, the ground state reaction may be used. 1.4 The values stated in SI units are to be regarded as standard. No oth...

  18. 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

  19. Study on Prompt Fission Neutron Spectra and Associated Covariances for 235U(nth,f) and 239Pu(nth,f)

    Science.gov (United States)

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

    Prompt Fission Neutron Spectra (PFNS) are very important nuclear data for reactor neutronic calculation tools. Most of the international evaluated nuclear data libraries lie on the Madland-Nix model, which is a based on evaporation theory of fission fragments. But very scarce data can be found regarding the PFNS covariance matrix associated to these evaluations. As an illustration of the impact of the PFNS on neutronic calculations, we will show a Monte-Carlo calculation of the neutron flux received by a PWR vessel, using different PFNS evaluations. The neutrons that have the highest probability to contribute to the vessel flux are those that are emitted at the highest energies; however most of the fission neutrons are emitted around 2 MeV. These results show the necessity to have very precise PFNS evaluations, and a proper estimation of associated covariances. The estimation of the PFNS covariance matrix associated to a model, after adjustment of model parameters, will be shown. This is performed by the CONRAD code, developed at CEA Cadarache. The final goal of the study is to adjust the parameters involved in fission fragments de-excitation in the FIFRELIN Monte-Carlo code, also developed at CEA Cadarache, which computes the PFNS among other fission quantities, and to provide the associated PFNS covariance matrix. However for the moment we focused the study on three historically widely used PFNS models: Maxwellian, Watt and Madland-Nix models. The covariance matrix on the adjusted spectrum comes mainly from the systematic uncertainty on some experimental parameters - namely the normalization, background, detection efficiency, etc. In order to propagate this type of uncertainties properly, the marginalization technique is used. A close knowledge of the conditions in which a particular experimental PFNS has been measured is required, in order to have a correct estimation of the PFNS uncertainties after adjustment. In this work, we propagated the uncertainty on

  20. 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.

  1. 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

    2008-05-21

    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 (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 (10)B capture reactions. The (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 (10)B prompt gamma signals were tallied from 16 angular positions. Results demonstrate that for

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

    International Nuclear Information System (INIS)

    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

  3. 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

  4. 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.)

  5. Investigation of prompt fission neutron and gamma spectra with their covariance matrices - Application to 239Pu+nth, 238U+n1.8MeV,235U+nth

    International Nuclear Information System (INIS)

    Prompt fission neutron and gamma spectra as well as multiplicities are important for nuclear heating purpose. A recent tool, FIFRELIN, has been developed at Cadarache for simulating the de-excitation of the fission fragments (FF) in order to generate the quantities mentioned above within a single code. The input data required by the code are the pre-neutron mass and kinetic energy distributions. These distributions come from experiments. Additional models are used to sample the charge, spin and parity of the fragments. The excitation energy sharing between two complementary fragments has been detailed in previous works. When the FF characteristics are sampled (A, Z, KE, J, π) the de-excitation process can start. The first scheme is based on Weisskopf statistical theory for neutron emission and level density plus strength functions for gamma emission. The neutron emission is performed before the gamma emission (uncoupled scheme). The second one is a Hauser-Feshbach like scheme based on neutron and gamma transmission coefficients (neutron and gamma emissions are coupled). The whole simulation allows the estimation of fission observables such as prompt fission neutron and gamma spectra as well as multiplicities but also distributions of all fission-related quantities. Various thermal, fast and spontaneous fissioning systems have been studied. In addition, a coupling algorithm between FIFRELIN and the CONRAD nuclear data evaluation code has been initiated in order to generate covariance matrices related to prompt fission spectra. (authors)

  6. Determination of average fission fraction produced by 14 MeV neutrons in assemblies with large volume of depleted uranium

    International Nuclear Information System (INIS)

    The average fission fraction of 238U caused by 14 MeV neutrons in assemblies with large volume depleted uranium has been determined. The measured value of pf238U (R∞depleted)14 was 0.897 ± 0.036. Measurements were also completed for neutron flux distribution and average fission fraction of 235U isotope in depleted uranium sphere. Values of pf238U (Rdepleted) have been obtained by using a series of uranium spheres. For a sphere with Φ 600 the pf23'8U (R300depleted) is 0.823 ± 0.041, the density of depleted uranium assembly is 18.8g/cm3 and total weight of assembly is about 2.8t

  7. 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)

  8. 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)

  9. Fission spectrum averaged cross section measurements of some neutron threshold reactions of relevance to medical radionuclide production

    International Nuclear Information System (INIS)

    A resume is given of radiochemical measurements of nuclear reaction cross sections relevant to the production of some medically important radionuclides carried out at PINSTECH during the last decade. Systematic studies on fission neutron spectrum averaged cross sections of several threshold reactions, like (n, 2n), (n, p) and (n, α) on titanium, ruthenium, europium and dysprosium for the production of 45Ti, 96Tc, 153Sm and 153Gd are described. (orig.)

  10. Elemental Characterization of Single-Wall Carbon Nanotube Certified Reference Material by Neutron and Prompt gamma Activation Analysis

    Czech Academy of Sciences Publication Activity Database

    Kučera, Jan; Bennett, J. W.; Oflaz, R.; Paul, R. L.; De Nadai Fernandes, E. A.; Kubešová, Marie; Bacchi, M. A.; Stopic, A. J.; Sturgeon, R. E.; Grinberg, P.

    2015-01-01

    Roč. 87, č. 7 (2015), s. 3699-3705. ISSN 0003-2700 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2011019 Institutional support: RVO:61389005 Keywords : Neutron Activation Analyses * nanotechnology * Carbon nanotubes * Chemical activation * Single-walled carbon nanotubes (SWCN) Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 5.636, year: 2014

  11. 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-...

  12. New insights into frontier of nuclear structure of neutron-rich nuclei by means of prompt fission γ ray measurements at gammasphere (I: section 1 and section 2)

    International Nuclear Information System (INIS)

    New insights have been gained into the frontiers of nuclear structure of neutron-rich nuclei by means of γ-γ-γ and γ-γ (θ) coincidences of prompt γ rays emitted in the spontaneous fission of 252Cf at Gammasphere. Over 5.7 x 1011 triple-and higher-fold coincidence events and the less-compressed cube data provide excellent conditions for searches and studies over a wide unknown range with more neutron excess. High-spin yrast and near yrast level schemes of neutron-rich nuclei in regions of physics interest have been identified for the first time, or extensively extended and expanded compared to previous preliminary measurements. Chiral symmetry breaking was recently identified in even-even neutron-rich 110,112Ru and 108Mo isotopes. The former have the largest lowering of ground state energy when axial symmetry is broken, and near maximum triaxiality was deduced in the isotopes. By exhibiting all the fingerprints for chiral doubling, especially the best energy degeneracy, the doublet bands observed in these Ru and Mo isotopes are the best examples of chiral properties reported in this region. The evolution of chirality from γ-soft 108Ru to triaxial 110,112Ru is proposed. Tilted axis cranking (TAC) calculations extended by random phase approximation (RPA) calculations can explain the features of the doublet bands in terms of a soft chiral vibration for these even-even nuclei. The chirality in these even-even nuclei cannot be reduced to the simple geometrical picture as in odd-odd nuclei. Instead, in these even-even nuclei the tendency to chirality comes about from the interplay of all the neutrons in the open shell. Systematic studies of the N = 83 isotonic chain in the vicinity of the doubly-magic 132Sn have yielded a wealth of spectroscopic information in this attractive region. The new data of N = 83 isotones 135Te (Z = 52), 136I (Z = 53), 137Xe (Z = 54), 138Cs (Z = 55) and 139Ba (Z = 56), especially the observation of the long-sought level scheme of 138Cs

  13. The Prompt Gamma-Ray, Prompt Electron and Prompt X-Ray Spectra Associated with Fission Fragments of Specific Mass

    International Nuclear Information System (INIS)

    Well-defined prompt gamma-rays, prompt-conversion elections and prompt K-X-rays have been observed in coincidence with moving fission fragments of Cf252. In a few cases, the masses and charges of the nuclei emitting the gamma-rays and conversion electrons have been identified. The gamma-ray, prompt-electron and prompt X-ray energies as well as the two fission fragments energies were measured with high-resolution solid-state detectors. The masses of the fragments were deduced from their energies, and the nuclear charges were determined by measuring the K-X - ray energies associated with different masses. The magnitude and sign of the Doppler shift in gamma-ray energy allowed assignment of the gamma-ray lines to single members of fragment pairs. The Doppler shift also provides an independent measure of the fragment velocity and hence the fragment mass after neutron emission. The results of the X-ray measurements are consistent with the view that the majority of the prompt X-rays emitted during the spontaneous fission of Cf252 are the result of internal conversion during the de-excitation of low-energy collective states of the primary fission fragments. Apart from the specific results discussed above, the most important consequence of these experiments has been the demonstration that it is possible to study the properties of individual fission fragments, as identified by their characteristic radiations, rather than studying the properties of an average fission fragment with an average mass and charge. The consequences of this advance in the technique of studying fission fragments ate being explored. (author)

  14. 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.

  15. Prompt temperature feedback coefficient measurement of TRR-1/M 1

    International Nuclear Information System (INIS)

    Prompt temperature feedback coefficient measurement of TRR-1M/1 (TRIGA MARK III) at the Office of Atomic Energy for Peace was carried out by direct measurements of heat transfer and reactor power characteristics during small power excursion experiment (reactivities less than 60 cent). An instrumented fuel element at position Bl was used to measure the temperature characteristic of fuel elements. From measured reactivities and heat transfer, prompt temperature feedback coefficient was calculated by using prompt-jump and one-delayed-neutron-group approximated diffusion equation, Newton's Law of Cooling, and linear reactivity equation. The core loading was mainly standard fuel elements. Averaged value of prompt temperature feedback coefficient obtained was-1.39 cent/degree C over the temperature range from 53 degree C to 57 degree C. The result is comparable to that obtained, by similar experiment, at the University of Arizona and about 16 percent above that reported by General Atomic Company, supplier of the reactor

  16. 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.

  17. FPGA based computation of average neutron flux and e-folding period for start-up range of reactors

    International Nuclear Information System (INIS)

    Pulse processing instrumentation channels used for reactor applications, play a vital role to ensure nuclear safety in startup range of reactor operation and also during fuel loading and first approach to criticality. These channels are intended for continuous run time computation of equivalent reactor core neutron flux and e-folding period. This paper focuses only the computational part of these instrumentation channels which is implemented in single FPGA using 32-bit floating point arithmetic engine. The computations of average count rate, log of average count rate, log rate and reactor period are done in VHDL using digital circuit realization approach. The computation of average count rate is done using fully adaptive window size moving average method, while Taylor series expansion for logarithms is implemented in FPGA to compute log of count rate, log rate and reactor e-folding period. This paper describes the block diagrams of digital logic realization in FPGA and advantage of fully adaptive window size moving average technique over conventional fixed size moving average technique for pulse processing of reactor instrumentations. (author)

  18. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Beddoe, A.H.; Streat, S.J.; Hill, G.L.

    1984-03-01

    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.

  20. 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。

  1. 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.)

  2. 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.)

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

    Science.gov (United States)

    Martin, Julie-Fiona; Taieb, Julien; Chatillon, Audrey; Bélier, Gilbert; Boutoux, Guillaume; Ebran, Adeline; Gorbinet, Thomas; Grente, Lucie; Laurent, Benoit; Pellereau, Eric; Alvarez-Pol, Héctor; Audouin, Laurent; Aumann, Thomas; Ayyad, Yassid; Benlliure, Jose; Casarejos, Enrique; Cortina Gil, Dolores; Caamaño, Manuel; Farget, Fanny; Fernández Domínguez, Beatriz; Heinz, Andreas; Jurado, Beatriz; Kelić-Heil, Aleksandra; Kurz, Nikolaus; Nociforo, Chiara; Paradela, Carlos; Pietri, Stéphane; Ramos, Diego; Rodríguez-Sànchez, Jose-Luis; Rodríguez-Tajes, Carme; Rossi, Dominic; Schmidt, Karl-Heinz; Simon, Haik; Tassan-Got, Laurent; Vargas, Jossitt; Voss, Bernd; Weick, Helmut

    2015-12-01

    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.

  4. 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.)

  5. Mercury and gold concentrations of highly polluted environmental samples determined using prompt gamma-ray analysis and instrument neutron activation analysis

    International Nuclear Information System (INIS)

    The authors have established a method of determining mercury and gold in severely polluted environmental samples using prompt gamma-ray analysis (PGA) and instrumental neutron activation analysis (INAA). Since large amounts of mercury are constantly being released into the environment by small-scale gold mining in many developing countries, the mercury concentration in tailings and water has to be determined to mitigate environmental pollution. Cold-vapor atomic absorption analysis, the most pervasive method of mercury analysis, is not suitable because tailings and water around mining facilities have extremely high mercury concentrations. On the other hand, PGA can determine high mercury concentrations in polluted samples as it has an appropriate level of sensitivity. Moreover, gold concentrations can be determined sequentially by using INAA after PGA. In conclusion, the analytical procedure established in this work using PGA and INAA is the best way to evaluate the degree of pollution and the tailing resource value. This method will significantly contribute to mitigating problems in the global environment.

  6. Metal impurities profile in a 450kg multi-crystalline silicon ingot by Cold Neutron Prompt Gamma-ray Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Hani; Sun, Gwang Min; Kim, Ji seok; Oh, Mok; Chung, Yong Sam; Moon, Jong Hwa; Kim, Sun Ha; Baek, Sung Yeol; Tuan, Hoang Sy Minh [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    Metal impurities are harmful to multi-crystalline silicon solar cells. They reduce solar cell conversion efficiencies through increased carrier recombination. They are present as isolated point-like impurities or precipitates. This work is to study the concentration profiles of some metal impurities of the directionally solidified 450kg multi-crystalline silicon ingot grown for solar cell production. The concentration of such impurities are generally below 10{sup 15}cm{sup -3}, and as such cannot be detected by physical techniques such as secondary-ion-mass spectroscopy(SIMS). So, we have tried to apply Cold Neutron - Prompt Gamma ray Activation Analysis(CN-PGAA) at the HANARO reactor research. The impurity concentrations of Au, Mn, Pt, Mo of a photovoltaic grade multi-crystalline silicon ingot appear by segregation from the liquid to the solid phase in the central region of the ingot during the crystallization. In the impurities concentration of the bottom region is higher than middle region due to the solid state diffusion. Towards the top region the segregation impurities diffused, during cooling process.

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

    International Nuclear Information System (INIS)

    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.)

  8. Multiple Prompt Gamma-ray Analysis of Environmental Materials

    International Nuclear Information System (INIS)

    The k0-standardization method has been applied and evaluated at Hot Lab. Center, using the prompt gamma ray neutron activation analysis (PGNAA) facility of the Cf-252 neutron source. This method has been designed and calibrated and has proven useful for the analytical purpose. Ten sediment samples of Manzala Lake at the end of Egyptian Nile River were analyzed for elemental contents. Prompt gamma my activation analysis (PGAA) due to neutron capture was carded out using integrated system using 252Cf isotopic neutron source with a flux of 6.16E8 n/cm2.sec. TheK0-prompt gamma activation analysis were determined versus the 1951.1 KeV gamma-my of the 35CI(n,gamma) 36CI reaction as comparator. Validation of thc K0-PGAA or mono standard comparator method was applied in analyzing a standard reference material IAEA (soil-7) which gave a good agreement with literature. A method was set up to estimate high neutron absorbing elements like Cd, Sm and Gd in an environmental samples as well as the light and heavy elements B, Na, Mg, Si, P, S, CI, K, Ca, Sc, Fe, Co, Cu, As, Br and Ba concentrations in EI-Manzala Lake sediment samples. The average concentration values of these elements were calculated

  9. 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

  10. 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.

  11. New insights into frontier of nuclear structure of neutron-rich nuclei by means of prompt fission γ ray measurements at gammasphere (II : section 3 and section 4)

    International Nuclear Information System (INIS)

    By means of γ-γ-γ and γ-γ (θ)measurements of prompt fission γ rays from 252Cf using Gammasphere, new insights have been gained into the A ∼ 100 (Z ∼ 40, N > 56) neutron-rich region, which has long been of interest for shape transitions, shape coexistence and onset of deformations. The systematic investigations of odd-Z isotopes have revealed a shape transition from axially symmetric shapes with very large quadrupole deformations in Z = 39 (Y) to near maximum triaxial shapes with moderate quadrupole deformations in Z = 43 (Tc), 44(Ru), 45 (Rh) isotopes. The Nb (Z = 41) isotopes are found to be transitional with regard to this shape transition. The band-crossings observed in the even-N Tc and Rh isotopes are attributed to alignment of a pair of h11/2 neutrons. The long-expected sudden shape transition in Nb isotopic chain is now observed. The long-sought high-spin level scheme and deformed states in 100Nb (N = 59) were identified. The ground state of 100Nb was found to be strongly deformed, in disagreement with existing theory. The shape coexistence was confirmed in the nucleus, and the sudden shape transition in the Nb isotopic chain was seen to occur between N = 58 (spherical) to N = 59 (strongly deformed), in contrast to the sudden shape transition from N = 59 (spherical) to N = 60 (strongly deformed) in Sr (Z = 38), Y (Z = 39) and Zr (Z = 40) isotopic chains. The observation of strongly deformed ground state in 100Nb and its very large and irregular moments of inertia make 100Nb an especially interesting case for further theoretical studies. Recent detailed studies of octupole excitations in odd-Z Cs (Z = 55) and La (Z = 57) isotopes have discovered a sharp drop in electric dipole moments D0 in the Cs isotopic chain 141,143,144Cs, and, most likely, the previously reported moderate drop in D0 in 145,147La is extended sharply down in 148La. The sharp drops of D0 in Cs and La are most likely analogous to those reported in 146Ba and 224Ra, which were

  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. Measurement of (n,xn) reaction cross-sections using prompt {gamma} spectroscopy at neutron beams with high instantaneous flux; Mesure de sections efficaces de reaction (n,xn) par spectroscopie {gamma} prompte aupres d'un faisceau a tres haut flux instantane

    Energy Technology Data Exchange (ETDEWEB)

    Lukic, S

    2004-10-15

    The work presented in this thesis is situated in the context of the GEDEON program of neutron cross-section measurements. This program is motivated by the perspectives recently opened by projects of nuclear waste treatment and energy production. There is an obvious lack of experimental data on (n,xn) reactions in the databases, especially in the case of very radioactive isotopes. An important technique to measure cross-sections of these reactions is the prompt {gamma}-ray spectroscopy at white pulsed neutron beams with very high instantaneous flux. In this work, inelastic scattering and (n,xn) reactions cross-section measurements were performed on a lead sample from threshold to 20 MeV by prompt {gamma}-ray spectroscopy at the white neutron beam generated by GELINA facility in Geel, Belgium. Digital methods were developed to treat HPGe CLOVER detector signals and separate {gamma}-rays induced by the fastest neutrons from those belonging to the flash. Partial cross-sections for the production of several transitions in natural lead were measured and analyzed using theoretical calculations in order to separate the contributions of different reactions leading to the same residual isotope. Total cross-sections of the reactions in question were estimated. The results were compared to the TALYSS code theoretical calculations, as well as to other experimental results. This experiment has served to validate the method and it opens the way to measure (n,xn) reactions cross-sections with high instantaneous neutron flux on actinides, particularly the U{sup 233}(n,2n) reaction which is important for the thorium cycle. (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. The final power calibration of the IPEN/MB-01 nuclear reactor for various configurations obtained from the measurements of the absolute average neutron flux

    International Nuclear Information System (INIS)

    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 0.719.10-5 ampere to nuclear linear channel number 6 (a non-compensated ionization chamber). (author)

  16. 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)

  17. 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.

  18. Determination of the mass distribution of fission products of 232Th in a neutron spectrum with average energy of 5.0 MeV

    International Nuclear Information System (INIS)

    In this study, the aim is to determine the distribution percentages of fission products which occur with Th (n,f) reaction by the average spectrum method in a neutron cell which consist of three 241Am-Be neutron sources of 592 GBq each. The average spectrum energy of Am-Be neutron source for neutron energies above 1.4 MeV was calculated as 5.02 MeV by numerical integration. In the experiments, powder ThO: compound with 99.5 % purity was used and powder UO2 compound with again 99.5 % purity was used as reference material. In determining detector efficiency, gamma ray with well-known energies and intensities which are emitted by 234Th and 34mPa radioactive nuclides which form as a result of natural decay of U, were used. Because of the difference in densities of UO? and TI1O2 matrixes, in determining detector efficiency for ThO: matrix gamma self absorbtion correction was applied. 14 of the fission products formed as a result of Th (n,f) reaction with masses between 87 and 143 were observed and the mass distribution of 13 of them were measured. The obtained values were compared with the values in the literature and it was seen that they generally agreed

  19. Measurement of average cross section for Pa-233 (n, 2n) Pa-232 reaction to neutrons with fission-type reactor spectrum

    International Nuclear Information System (INIS)

    Among some nuclides concerning thorium fuel cycle, the reaction cross sections of Pa-233 should be thoroughly investigated because of its relatively long life of 27 days half life. In the present works, the average cross section for Pa-233(n,2n)Pa-232 reaction, which has been considered to contribute to the production of troublesome concomitant U-232, was initially measured using the Pa-233 specimen as pure as possible followed by the re-irradiation in a fission-type neutron spectrum. The purest Pa-233 was produced from the first thermal neutron irradiation of Th-oxide, which was selected from the viewpoint of low Th-230 content to avoid the production of bothering Pa-231 having a large cross section for thermal neutron capture reaction. The chemically isolated Pa-233 was immediately re-irradiated with reactor neutrons having fission-type reactor spectrum in KUR, along with some flux monitors for fast neutrons. After completely decaying out Pa-233 to U-233, the chemical purification of uranium was performed and the resultant uranium isotopes were analysed with an alpha-spectrometry. By using the activity ratios of U-232/U-233, the objective cross section was evaluated to be 52.1 mbarn with an estimated overall experimental error of 10 % after correcting the inevitable bypath reaction by small amount of Pa-231 content. (author)

  20. Progress in transactinium isotope neutron data measurements

    International Nuclear Information System (INIS)

    This paper reviews the present state of the techniques used in different laboratories for neutron data measurements on transactinium isotopes, with emphasis on recent developments and possible improvements. The different domains investigated are: fission cross sections, prompt neutrons from fission, delayed neutrons from fission, prompt fission neutron spectrum, prompt fission gamma-rays, (n,xn) reactions, capture cross sections and neutron scattering

  1. Project ''PHANTOM'' - measurement of the absorbed dose, the ''averaged LET'' and the thermal neutron fluence in a tissue equivalent Phantom onboard space station MIR

    International Nuclear Information System (INIS)

    A water filled phantom with a diameter of 35 cm was developed at the Institute for Biomedical Problems. This tissue equivalent phantom is equipped with 4 channels to deposit dosemeters in different depths. In the framework of the project 'PHANTOM' (phase 1-3) thermoluminescent dosemeters of the commercially available Types TLD - 600 and TLD - 700 were exposed from May 1997 to February 1999 for an overall of 572 days in the different channels (perpendicular and normal to the hull of the spacecraft) of the phantom. The phantom was positioned in the commander cabin, the board engineer cabin and in the module KWANT 2. Besides the measurement of the depth dose distribution, the 'averaged LET' was determined using the HTR - method. The HTR - method utilizes the different LET - efficiencies of the main - and the high temperature glow peaks of LiF dosemeters for the evaluation of the 'averaged LET' in mixed radiation fields. Therefore it is possible to calculate the depth distribution of the biologically relevant dose equivalent. The results show, that despite of the depth decrease of the absorbed dose, the depth dose equivalent is almost constant. This can be explained by the production of secondary particles inside the phantom. The flux of the thermal neutrons was determined using the pair method. Calibration was performed at the research reactor of the Austrian Universities. First results show, that the contribution of thermal neutrons are roughly 10% of the total neutron dose equivalent. (orig.)

  2. 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

  3. Prompt γ-ray activation analysis of Martian analogues at the FRM II neutron reactor and the verification of a Monte Carlo planetary radiation environment model

    International Nuclear Information System (INIS)

    Planetary radiation environment modelling is important to assess the habitability of a planetary body. It is also useful when interpreting the γ-ray data produced by natural emissions from radioisotopes or prompt γ-ray activation analysis. γ-ray spectra acquired in orbit or in-situ by a suitable detector can be converted into meaningful estimates of the concentration of certain elements on the surface of a planet. This paper describes the verification of a Monte Carlo model developed using the MCNPX code at University of Leicester. The model predicts the performance of a geophysical package containing a γ-ray spectrometer operating at a depth of up to 5 m. The experimental verification of the Monte Carlo model was performed at the FRM II facility in Munich, Germany. The paper demonstrates that the model is in good agreement with the experimental data and can be used to model the performance of an in-situ γ-ray spectrometer.

  4. 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...

  5. 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

  6. Measurement of fission neutron spectrum averaged cross sections of some threshold reactions on europium: small scale production of no-carrier-added 153Sm in a nuclear reactor

    International Nuclear Information System (INIS)

    Employing the activation technique in combination with radiochemical separations and high-resolution γ-ray spectroscopy fission neutron spectrum averaged cross sections were measured for several (n, 2n), (n, p) and (n, α) reactions on isotopes of europium. Our measurements constitute the first systematic studies. Of special interest was the investigation of 153Eu(n, p)153Sm reaction for the production of no-carrier-added 153Sm in a nuclear reactor. Using 100% enriched 153Eu target, 97.21 MBq 153Sm per batch can be produced which is, however, not sufficient for medical application. (orig.)

  7. 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)

  8. 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

    International Nuclear Information System (INIS)

    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 235U. 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)

  9. FERMILAB: Prompt forward muons

    International Nuclear Information System (INIS)

    There have been theoretical conjectures that the large diffractive charm cross-sections seen at the CERN Intersecting Storage Rings result from an intrinsic charm quark component at the one per cent level in the hadron. The semileptonic decays of such charm states would result in high energy prompt muons in the forward direction. A recent prompt muon experiment by a Caltech/Chicago/Fermilab/Rochester/Stanford collaboration indicates a very low rate for such prompt muons

  10. 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...

  11. 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

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

    International Nuclear Information System (INIS)

    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. (authors)

  13. Prompt radiation detectors to monitor target conditions

    DEFF Research Database (Denmark)

    Barnhart, T. E.; Engle, J. W.; Valdovinos, H. F.; Severin, Gregory; Nickles, R. J.

    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...

  14. 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

  15. 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

  16. Neutron-fragment and Neutron-neutron Correlations in Low-energy Fission

    Science.gov (United States)

    Lestone, J. P.

    2016-01-01

    A computational method has been developed to simulate neutron emission from thermal-neutron induced fission of 235U and from spontaneous fission of 252Cf. Measured pre-emission mass-yield curves, average total kinetic energies and their variances, both as functions of mass split, are used to obtain a representation of the distribution of fragment velocities. Measured average neutron multiplicities as a function of mass split and their dependence on total kinetic energy are used. Simulations can be made to reproduce measured factorial moments of neutron-multiplicity distributions with only minor empirical adjustments to some experimental inputs. The neutron-emission spectra in the rest-frame of the fragments are highly constrained by ENDF/B-VII.1 prompt-fission neutron-spectra evaluations. The n-f correlation measurements of Vorobyev et al. (2010) are consistent with predictions where all neutrons are assumed to be evaporated isotropically from the rest frame of fully accelerated fragments. Measured n-f and n-n correlations of others are a little weaker than the predictions presented here. These weaker correlations could be used to infer a weak scission-neutron source. However, the effect of neutron scattering on the experimental results must be studied in detail before moving away from a null hypothesis that all neutrons are evaporated from the fragments.

  17. 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

  18. 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.)

  19. 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

  20. Comparing the Effects of Echoic Prompts and Echoic Prompts Plus Modeled Prompts on Intraverbal Behavior

    Science.gov (United States)

    Valentino, Amber L.; Shillingsburg, M. Alice; Call, Nathan A.

    2012-01-01

    We compared strategies to teach vocal intraverbal responses to an adolescent diagnosed with autism and Down syndrome. One strategy involved echoic prompts only. The second strategy involved an echoic prompt paired with a modeled prompt in the form of sign language. Presenting the modeled prompt with the echoic prompt resulted in faster acquisition…

  1. Calculations of Nuclear Astrophysics and Californium Fission Neutron Spectrum Averaged Cross Section Uncertainties Using ENDF/B-VII.1, JEFF-3.1.2, JENDL-4.0 and Low-fidelity Covariances

    International Nuclear Information System (INIS)

    Nuclear astrophysics and californium fission neutron spectrum averaged cross sections and their uncertainties for ENDF materials have been calculated. Absolute values were deduced with Maxwellian and Mannhart spectra, while uncertainties are based on ENDF/B-VII.1, JEFF-3.1.2, JENDL-4.0 and Low-Fidelity covariances. These quantities are compared with available data, independent benchmarks, EXFOR library, and analyzed for a wide range of cases. Recommendations for neutron cross section covariances are given and implications are discussed

  2. Even-odd effects in the prompt fission emission of even Z actinides

    Directory of Open Access Journals (Sweden)

    Tudora Anabella

    2016-01-01

    Full Text Available The investigation of even-odd effects in the prompt emission of even Z actinides showed a sawtooth shape of ν(Z with staggering in the asymmetric fission region. Average prompt emission quantities as a function of A, e.g. ν(A, of even Z fragmentations are higher than those of odd Z fragmentations and they exhibit oscillations with a periodicity of about 5 mass units in the asymmetric fission region. This periodicity is not due to the Z even-odd effect in fragment distributions. The even-odd effect in (TKE is increasing with increasing TKE and it decreases with increasing mass of the fissioning nucleus. The global even-odd effect in total average prompt emission quantities is decreasing with increasing mass of the fissioning nucleus. In the case of an even-odd fissioning nucleus, 234U(n,f, the global even-odd effect in prompt emission quantities exhibits a very slow variation with the incident neutron energy.

  3. Even-odd effects in the prompt fission emission of even Z actinides

    Science.gov (United States)

    Tudora, Anabella; Hambsch, Franz-Josef; Giubega, Georgiana; Visan, Iuliana

    2016-03-01

    The investigation of even-odd effects in the prompt emission of even Z actinides showed a sawtooth shape of ν(Z) with staggering in the asymmetric fission region. Average prompt emission quantities as a function of A, e.g. ν(A), of even Z fragmentations are higher than those of odd Z fragmentations and they exhibit oscillations with a periodicity of about 5 mass units in the asymmetric fission region. This periodicity is not due to the Z even-odd effect in fragment distributions. The even-odd effect in (TKE) is increasing with increasing TKE and it decreases with increasing mass of the fissioning nucleus. The global even-odd effect in total average prompt emission quantities is decreasing with increasing mass of the fissioning nucleus. In the case of an even-odd fissioning nucleus, 234U(n,f), the global even-odd effect in prompt emission quantities exhibits a very slow variation with the incident neutron energy.

  4. 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.

  5. 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.)

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

    International Nuclear Information System (INIS)

    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(nth, f), 239Pu(nth,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. (orig.)

  7. 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)

  8. 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 ).

  9. Binding energies of the 1g sub(9/2) and 1h sub(11/2) neutron and average two-body effective interactions V sub(pn) and V sub(nn)

    International Nuclear Information System (INIS)

    The binding energies of the single particle or hole orbitals of the 1g sub(9/2) and 1h sub(11/2) neutron shells are given as a simple linear function of the active valence proton and neutron numbers. This function is derived theoretically by the assumption of constant two-body effective interactions average V sub(ph) and average V sub(nn) in the relevant proton and neutron shell spaces. These values appearing in the function as the coefficients of the proton and neutron numbers are determined from the experimental binding energies by a least-squares fit. The good quality of fit between the experimental and fitted binding energies implies the plausibility of the formula and the assumption. The determined average V sub(pn) and average V sub(nn) have the absolute values and the signs consistent with those in the literature. The effective interactions in the case of the 1g sub(9/2) hole is found to decrease with increasing mass number. (author)

  10. 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)

  11. A study of television imaging system for fast neutron radiography

    International Nuclear Information System (INIS)

    The neutron radiography with fast neutron beam is a very useful imaging technique for thicker objects, especially those composed of hydrogen-rich materials which are sometimes difficult to image by thermal neutron radiography. The fast neutron radiography has not been studied so much as the thermal neutron radiography. The fast neutron radiography has been studied at the fast neutron source reactor 'Yayoi' of the University of Tokyo built in Tokai-mura. The average neutron energy of the Yayoi is about 1 MeV, and the peak neutron flux at the core center is 0.8 x 1012 at the maximum operating power of 2 kW. In the experiment on fast neutron radiography, a CR39 nuclear track detector has been used successfully. But in the Yayoi radiography procedure, about 24 hours were required for obtaining an imaging result. To get a prompt imaging result and a real-time imaging result, it is necessary to develop a fast neutron television system, and in this paper, a new fast neutron TV system is proposed. The main difference is the converter material sensitive to fast neutrons. The study on the fast neutron TV system was carried out by using the Baby Cyclotron of Japan Steel Works, and the good images were realized. (K.I.)

  12. 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...

  13. 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.

  14. Measurements of fission product yield in the neutron-induced fission of 238U with average energies of 9.35 MeV and 12.52 MeV

    International Nuclear Information System (INIS)

    The yields of various fission products in the neutron-induced fission of 238U with the flux-weighted averaged neutron energies of 9.35 MeV and 12.52 MeV were determined by using an off-line gamma ray spectroscopic technique. The neutrons were generated using the 7Li(p, n) reaction at Bhabha Atomic Research Centre-Tata Institute of Fundamental Research Pelletron facility, Mumbai. The gamma- ray activities of the fission products were counted in a highly-shielded HPGe detector over a period of several weeks to identify the decaying fission products. At both the neutron energies, the fission-yield values are reported for twelve fission product. The results obtained from the present work have been compared with the similar data for mono-energetic neutrons of comparable energy from the literature and are found to be in good agreement. The peak-to-valley (P/V) ratios were calculated from the fission-yield data and were found to decreases for neutron energy from 9.35 to 12.52 MeV, which indicates the role of excitation energy. The effect of the nuclear structure on the fission product-yield is discussed.

  15. 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...

  16. Prompting Designers to Design

    DEFF Research Database (Denmark)

    Ahmed, Saeema

    2007-01-01

    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...

  17. Prompting Designers to Design

    DEFF Research Database (Denmark)

    Ahmed, Saeema

    2007-01-01

    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 pr...... literature related to: 1) an understanding of how engineering designers search for information and 2) an understanding of the nature of experience in engineering design. Hence these are reviewed in the following sections.......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...

  18. Prompting Designers to Design

    DEFF Research Database (Denmark)

    Ahmed, Saeema

    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...

  19. 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.

  20. Average Interest

    OpenAIRE

    George Chacko; Sanjiv Ranjan Das

    1997-01-01

    We develop analytic pricing models for options on averages by means of a state-space expansion method. These models augment the class of Asian options to markets where the underlying traded variable follows a mean-reverting process. The approach builds from the digital Asian option on the average and enables pricing of standard Asian calls and puts, caps and floors, as well as other exotica. The models may be used (i) to hedge long period interest rate risk cheaply, (ii) to hedge event risk (...

  1. Prompting Strategies for Introducing Opera.

    Science.gov (United States)

    Beck, Charles R.

    2002-01-01

    Describes how to introduce opera to students through the use of prompting strategies. Explains that these strategies encourage active participation by students and help to improve listening skills. Focuses on prompting strategies, such as matching characters to songs, identifying, and sequencing songs. (CMK)

  2. 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)

  3. 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

  4. 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

  5. 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)

  6. Neutron scattering studies in the actinide region

    International Nuclear Information System (INIS)

    This report discusses the following topics: Prompt fission neutron energy spectra for 235U and 239Pu; Two-parameter measurement of nuclear lifetimes; ''Black'' neutron detector; Data reduction techniques for neutron scattering experiments; Inelastic neutron scattering studies in 197Au; Elastic and inelastic scattering studies in 239Pu; and neutron induced defects in silicon dioxide MOS structures

  7. 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.

  8. Monte-Carlo Hauser-Feshbach simulations of prompt fission gamma-ray properties

    Science.gov (United States)

    Stetcu, Ionel; Talou, Patrick; Kawano, Toshihiko; Jandel, Marian

    2014-09-01

    Properties of prompt fission neutrons and γ rays, emitted before the weak decays of the fission fragments toward stability, are important for both nuclear technologies and a better understanding of the fission process. In the present work, we use the Hauser-Feshbach model to simulate the de-excitation of the fully accelerated fission fragments treated as compound nuclei. Our Monte-Carlo implementation of the Hauser-Feshbach statistical model, which takes into account the competition between the neutron and γ emissions, allows the description of both average quantities, like in the Los Alamos model, and correlations between the emitted particles. Our simulations will be compared against available experimental data and current evaluations. In particular, we will compare our average γ-ray spectrum with recent measurements at the research reactor KFKI in Budapest for the 235U(nth , f) and 252Cf(sf) reactions, as well as multiplicity-dependent distributions obtained at the DANCE facility at LANSCE. Properties of prompt fission neutrons and γ rays, emitted before the weak decays of the fission fragments toward stability, are important for both nuclear technologies and a better understanding of the fission process. In the present work, we use the Hauser-Feshbach model to simulate the de-excitation of the fully accelerated fission fragments treated as compound nuclei. Our Monte-Carlo implementation of the Hauser-Feshbach statistical model, which takes into account the competition between the neutron and γ emissions, allows the description of both average quantities, like in the Los Alamos model, and correlations between the emitted particles. Our simulations will be compared against available experimental data and current evaluations. In particular, we will compare our average γ-ray spectrum with recent measurements at the research reactor KFKI in Budapest for the 235U(nth , f) and 252Cf(sf) reactions, as well as multiplicity-dependent distributions obtained at the

  9. Average nuclear surface properties

    International Nuclear Information System (INIS)

    The definition of the nuclear surface energy is discussed for semi-infinite matter. This definition is extended also for the case that there is a neutron gas instead of vacuum on the one side of the plane surface. The calculations were performed with the Thomas-Fermi Model of Syler and Blanchard. The parameters of the interaction of this model were determined by a least squares fit to experimental masses. The quality of this fit is discussed with respect to nuclear masses and density distributions. The average surface properties were calculated for different particle asymmetry of the nucleon-matter ranging from symmetry beyond the neutron-drip line until the system no longer can maintain the surface boundary and becomes homogeneous. The results of the calculations are incorporated in the nuclear Droplet Model which then was fitted to experimental masses. (orig.)

  10. 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.

  11. 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)

  12. Study of yield and average cross sections of the secondary reactions of charged particles produced by 14 MeV neutrons on light nuclei. Application to the determination of hydrogen, deuterium and oxygen-18

    International Nuclear Information System (INIS)

    The yield and average cross section for the reactions 11B(p,n)11C, 12C(p,γ)13N, 13C(p,n)13N, 12C(d,n)13N, 14N(p,α)11C , 16O(p,α)13N, 16O(d,n)17F, 16O(t,n)18F, and 18O(p,n)18F have been measured in different compounds. The charged particles were created in the samples themselves either through recoil by scattering of 14 MeV neutrons of hydrogen and deuterium, or by the (n,t) reaction on 6Li using thermal neutrons. The yields of reactions 12C(d,n); 16O(p,α); 16O(t,n) and 18O(p,n) have been measured using proton deuteron and triton spectra generated by 14 MeV neutrons in the reactions D(n,p)2n; 6Li(n,d); 7Li(n,d) and 10B(n,d); 7Li(n,t) and 10B(n,t), respectively. On the other hand the hydrogen mass fraction in an arbitrary matrix is determined using the scattered protons emitted from a sample, to activate a boron pellet using the 11B(p,n)11C reaction. With a natural boron detector, detection limits of 0.2% have been achieved using a 14 MeV neutron generator with a yield of ∼1011S-1. 72 figs.; 17 tabs.; 105 refs. (author)

  13. Neutrons in cancer therapy

    Science.gov (United States)

    Allen, Barry J.

    1995-03-01

    The role of neutrons in the management of cancer has a long history. However, it is only in recent years that neutrons are beginning to find an accepted place as an efficacious radiation modality. Fast neutron therapy is already well established for the treatment of certain cancers, and clinical trials are ongoing. Californium neutron sources are being used in brachytherapy. Boron neutron capture therapy has been well tested with thermal neutrons and epithermal neutron dose escalation studies are about to commence in the USA and Europe. Possibilities of neutron induced auger electron therapy are also discussed. With respect to chemotherapy, prompt neutron capture analysis is being used to study the dose optimization of chemotherapy in the management of breast cancer. The rationales behind these applications of neutrons in the management of cancer are examined.

  14. ARMA modelling of neutron stochastic processes with large measurement noise

    International Nuclear Information System (INIS)

    An autoregressive moving average (ARMA) model of the neutron fluctuations with large measurement noise is derived from langevin stochastic equations and validated using time series data obtained during prompt neutron decay constant measurements at the zero power reactor RB in Vinca. Model parameters are estimated using the maximum likelihood (ML) off-line algorithm and an adaptive pole estimation algorithm based on the recursive prediction error method (RPE). The results show that subcriticality can be determined from real data with high measurement noise using much shorter statistical sample than in standard methods. (author)

  15. Prompt and Delayed Gamma-Rays from Fission

    International Nuclear Information System (INIS)

    The following data about gamma-rays from fission are reported and discussed; Total prompt gamma-ray spectrum, and average number and energy of gamma-rays; X-rays in prompt fission, and excitation of X-rays in matter; gamma-ray spectra as a function of the mass ratio in fission, gamma-lines in those spectra, and Doppler effect-, anisotropy in gamma-emission relative to the direction of fragments; average gamma-energy and gamma-spectra as a function of mass of the fission products; delayed gamma-rays; delayed gamma-rays as a function of fission product mass. (author)

  16. 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)

  17. Theoretical descriptions of neutron emission in fission

    International Nuclear Information System (INIS)

    Brief descriptions are given of the observables in neutron emission in fission together with early theoretical representations of two of these observables, namely, the prompt fission neutron spectrum N(E) and the average prompt neutron multiplicity bar νp. This is followed by summaries, together with examples, of modern approaches to the calculation of these two quantities. Here, emphasis is placed upon the predictability and accuracy of the new approaches. In particular, the dependencies of N(E) and bar νp upon the fissioning nucleus and its excitation energy are discussed. Then, recent work in multiple-chance fission and other recent work involving new measurements are presented and discussed. Following this, some properties of fission fragments are mentioned that must be better known and better understood in order to calculate N(E) and bar νp with higher accuracy than is currently possible. In conclusion, some measurements are recommended for the purpose of benchmarking simultaneous calculations of neutron emission and gamma emission in fission. 32 refs., 26 figs

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

    OpenAIRE

    Blanc A.; Chebboubi A.; de France G.; Drouet F.; Faust H.; Jentschel M.; Kessedjian G.; Köster U.; Leoni S.; Materna T.; Mutti P.; Panebianco S.; Sage C.; Simpson G.; Soldner T.

    2015-01-01

    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...

  19. 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

  20. 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)

  1. Neutron data evaluation of 232Th

    International Nuclear Information System (INIS)

    Consistent evaluation of 232Th measured data base is performed. Hauser-Feshbach- Moldauer theory, coupled channel model and double-humped fission barrier model are employed. Total, differential scattering, fission, capture and (n,xn) data are consistently reproduced as a major constraint for inelastic scattering cross section estimate. The direct excitation of ground state and higher band levels is calculated within rigid rotator and soft (deformable) rotator model, respectively. Structures evident in measured neutron emission spectra are correlated with excitation of levels of Kπ=0- and Kπ=0+, 2+ bands. Prompt fission neutron spectra data are described. Average resonance parameters are provided, which reproduce evaluated cross sections in the range of 10-150 kev. (author)

  2. 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...

  3. Study on the influence of prompt fission γ-ray and delayed γ-ray on reactor internals heating rate

    International Nuclear Information System (INIS)

    To improve the accuracy of the calculated reactor internals heating rate in the design of nuclear power plants, this paper studied the contribution of prompt fission γ to the reactor internals heating rate based on the original method of MCNP external neutron source model. The results revealed that the reactor internals heating rate increased by 9%∼38% with prompt fission γ taken into account and the internals nearer to the core had a lager increment. In addition, it is believed after analysis that the contribution of the delayed γ on reactor internals heating rate is similar to the prompt fission γ. Therefore, when calculating reactor internals heating rate, in addition to the neutron source and neutron capture γ, prompt fission γ and delayed γ should also be considered. (authors)

  4. Statistical and evaporation models for the neutron emission energy spectrum in the center-of-mass system from fission fragments

    International Nuclear Information System (INIS)

    The neutron emission energy spectra in the CMS (center-of-mass) frame from two compound nuclei produced by fission are studied. The neutron spectra calculated with the Hauser–Feshbach statistical model are compared with the evaporation theory, and the definition of the temperature is revisited. Using the Monte Carlo technique we average the CMS neutron spectra from many fission fragments to construct the representative CMS spectrum from both the light and heavy fragments. The CMS spectra for each fission fragment pair are also converted into the laboratory frame to calculate the total prompt fission neutron spectrum that can be observed experimentally. This is compared to measured laboratory data for thermal neutron induced fission on 235U. We show that the Hauser–Feshbach calculation gives a different spectrum shape than the Madland–Nix model calculation

  5. 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.

  6. 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)

  7. Study of neutron focusing at the Texas Cold Neutron Source: Progress report

    International Nuclear Information System (INIS)

    The purpose of this three year study is to develop a neutron focusing system to be used with the Texas Cold Neutron Source (TCNS) to produce an intense beam of neutrons. A prompt gamma activation analysis (PGAA) facility will also be designed, setup, and tested under this DOE grant. During the first year of the DOE grant, a new procedure was developed and used to design a focusing converging guide consisting of truncated rectangular cone sections. Detailed calculations were performed using a 3-D Monte Carlo code which the authors wrote to trace neutrons through the existing curved guide of the TCNS into the proposed converging guide. Using realistic reflectivities for Ni-Ti supermirrors, they obtained gains of 4 to 5 for the neutron flux averaged over an area of 1 x 1 cm. Two graduate students were supported by the first year of the DOE grant. Both have passed the Nuclear Engineering qualifying examination and have been admitted to candidacy for the doctoral degree at The University of Texas at Austin. Their programs of study and dissertation projects have been approved by the appropriate committees

  8. PASSING STANDARDIZED ASSESSMENTS WITH FADING PROMPTS

    Directory of Open Access Journals (Sweden)

    Amy Marie GREENE

    2015-11-01

    Full Text Available Introduction: No Child Left Behind Act of 2001 mandates that all students perform at a level of proficient on state assessments. This includes students with learning and intellectual disabilities who are inherently performing below grade level. Given that schools are held accountable for meeting these goals and some states are not allowing students to graduate if they do not pass the assessments, this is a large concern for students, parents, teachers, and administration Method: Forty-five students with a disability in writing or an intellectual disability participated in this quasi-experimental, single-group, pretest-posttest design that evaluated the effectiveness of the Fading Prompts through Graphic Organizers method for students with learning and intellectual disabilities in written expression as measured according to the Pennsylvania System of School Assessment. Results: Data analyses were conducted through the use of four dichotomies for percent differences, which compared teacher administered pretests and posttests, pretests and the state administered PSSA, teacher administered posttests and the PSSA, and the participants’ PSSA and the average state PSSA score. All forty-five students performed at a below basic level during baseline and a proficient level on the posttest. The learned skills generalized to the PSSA with forty-three students earning a passing score of proficient, while two students advanced to basic. Conclusion: Based on the outcomes of this study, it is highly recommended that this program be utilized at least for students with learning and intellectual disabilities until further research can be done.

  9. 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

  10. 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.

  11. 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.

  12. 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 :...

  13. 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

  14. Characteristics of prompt fission gamma-ray emission - Experimental results and predictions

    International Nuclear Information System (INIS)

    Systematics from 2001, describing prompt fission gamma-ray spectra (PFGS) characteristics as function of mass and atomic number of the fissioning system, has been revisited and parameters have been revised based on recent experimental results. Although originally expressed for spontaneous and thermal neutron-induced fission, validity for fast neutrons was assumed and applied to predict PFGS characteristics for the reaction n + 238U up to incident neutron energies of En = 20 MeV. The results from this work are in good agreement with corresponding results from both model calculations and experiments. (authors)

  15. Neutron capture cross section measurements for 197Au from 3.5 to 84 keV at GELINA

    OpenAIRE

    Massimi, C.; BECKER BJÖRN; Dupont, E.; Kopecky, Stefan; LAMPOUDIS CHRISTOS; Massarczyk, R.; Moxon, M.; PRONYAEV V. G; Schillebeeckx, Peter; Sirakov, I.; WYNANTS Ruud

    2014-01-01

    Cross section measurements have been performed at the time-of-flight facility GELINA to determine the average capture cross section for 197Au in the energy region between 3.5 keV and 84 keV. Prompt gamma-rays, originating from neutron induced capture events, were detected by two C6D6 liquid scintillators. The sample was placed at about 13 m distance from the neutron source. The total energy detection principle in combination with the pulse height weighting technique was applied. The energy de...

  16. anti νsub(p) neutron fission of 232Th near threshold

    International Nuclear Information System (INIS)

    The average number of prompt neutrons emitted per fission, anti νsub(p), for 232Th(n,f) has been measured between 1.35 and 2.1 MeV. No large maximum in anti νsub(p) at about 1.4 MeV has been seen. The behaviour of anti νsub(p) and of anti Esub(K), the average total fragment kinetic energy, have been calculated using both a double-humped and triple-humped fission potential barrier. Significant disagreement with existing anti Esub(K) data for 232Th(n,f) is observed

  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. Development of Cold Neutron Activation Station at HANARO Cold Neutron Source

    International Nuclear Information System (INIS)

    A new cold neutron source at the HANARO Research Reactor had been constructed in the framework of a five-year project, and ended in 2009. It has seven neutron guides, among which five guides were already allocated for a number of neutron scattering instruments. A new two-year project to develop a Cold Neutron Activation Station (CONAS) was carried out at the two neutron guides since May 2010, which was supported by the program of the Ministry of Education, Science and Technology, Korea. Fig. 1 shows the location of CONAS. CONAS is a complex facility including several radioanalytical instruments utilizing neutron capture reaction to analyze elements in a sample. It was designed to include three instruments like a CN-PGAA (Cold Neutron - Prompt Gamma Activation Analysis), a CN-NIPS (Cold Neutron - Neutron Induced Pair Spectrometer), and a CN-NDP (Cold Neutron - Neutron-induced prompt charged particle Depth Profiling). Fig. 2 shows the conceptual configuration of the CONAS concrete bioshield and the instruments. CN-PGAA and CN-NIPS measure the gamma-rays promptly emitted from the sample after neutron capture, whereas CN-NDP is a probe to measure the charged particles emitted from the sample surface after neutron capture. For this, we constructed two cold neutron guides called CG1 and CG2B guides from the CNS

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  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. 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.

  5. Neutron Generators for Analytical Purposes

    International Nuclear Information System (INIS)

    This publication addresses recent developments in neutron generator (NG) technology. It presents information on compact instruments with high neutron yield to be used for neutron activation analysis (NAA) and prompt gamma neutron activation analysis in combination with high count rate spectrometers. Traditional NGs have been shown to be effective for applications including borehole logging, homeland security, nuclear medicine and the on-line analysis of aluminium, coal and cement. Pulsed fast thermal neutron analysis, as well as tagged and timed neutron analysis, are additional techniques which can be applied using NG. Furthermore, NG can effectively be used for elemental analysis and is also effective for analysis of hidden materials by neutron radiography. Useful guidelines for developing NG based research laboratories are also provided in this publication.

  6. 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.

  7. 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.

  8. Tagged neutrons from portable neutron generator for detection of high explosives and fissile materials in cargo containers

    International Nuclear Information System (INIS)

    Two prototypes of measuring inspection systems created in VNIIA and intended for active interrogation of cargo containers to detect high explosives (HE) and fissile materials (FM) are presented. Both systems are based on 14 MeV tagged neutrons (API) method. The first system (for HE detection) includes: - VNIIA portable neutron generator ING-27 with built-in segmented 9-pixel semiconductor α-detector (30 x 30 mm2); - 12 scintillation γ-detectors based on bismuth germanate crystal (BGO) with size of diameter 63 x 63 mm2; - γ-detector shielding from primary neutron flux (borated polyethylene + iron); - electronics for data acquisition and processing system. Experimental results on detection of 50 kg of HE simulator melamine (C3H6N6) are presented for wood and iron matrix as container mock-up with average density of 0.4 g/cm3 and for different distances of HE simulator from container front wall. With increase of distance from container wall to melamine the excess of signal over background decreases. This is conditioned both by measurement geometry and attenuation of probe neutron beam and produced inelastic γ-quanta by container filling. Various decision-making algorithms and improvements are discussed. The second system (for FMdetection) includes the same neutron generator, six plastic (polystyrene) large square (120 x 9 x 9 cm3) scintillators for detection of multiple coincidences of prompt neutrons and fission γ-quanta from FM. Radiation types were distinguished according to time of flight. Measurements were conducted for depleted uranium (8 kg) arranged in container filled with wood and iron of 0.4 g/cm3 average density at the distance of 60 cm from container front wall. Excess of two- and three-fold coincidences from uranium over the corresponding background value was observed both in neutron and γ-channels. The best signal/background ratio was revealed for container filled with iron. (author)

  9. 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

  10. Effects of variations on slopes of yield and average kinetic energy curves as a function of fragment mass on standard deviation of final kinetic energy distribution from thermal neutron induced fission of 235U

    International Nuclear Information System (INIS)

    The mass and kinetic energy distributions of fragments from thermal neutron induced fission of 233U have been studied using a Monte-Carlo simulation. In our previous work [1] we reproduce the two pronounced broadenings in the standard deviation (SD) of the kinetic energy distribution of the final fragment at mass number around m=109, and m=125, respectively, which is agreement with the experimental data obtained by Belhafaf et al. [2] (author).

  11. 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

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

    International Nuclear Information System (INIS)

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

  13. Determination of protein content in seeds by prompt gamma-ray spectrometry

    International Nuclear Information System (INIS)

    The protein level in seeds can be directly calculated through the determination of the nitrogen content in grains. The authors show here that the radioactive thermal neutron capture prompt gamma-rays technique can be used to determine the nitrogen content in grains without chemical destruction, with good precision and relative rapidity, by detecting the prompt gamma rays emitted by the 14N(n,γ)15N reaction product. The samples were irradiated in the tangential tube of the IEA-R1 research reactor, in Sao Paulo, and a pair spectrometer was used for the detection of the prompt gamma-rays. The nitrogen content was determined in several samples of soybean, common bean, peas and rice and the results compared with typical nitrogen content values for each grain. 33 references, 1 figure, 1 table

  14. 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.)

  15. 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.)

  16. 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.)

  17. 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.

  18. Prompt dipole radiation in fusion reactions

    CERN Document Server

    Martin, Brunella; Agodi, Concetta; Alba, Rosa; Baran, Virgil; Boiano, Alfonso; Cardella, Giuseppe; Colonna, Maria; Coniglione, Rosa; De Filippo, Enrico; Del Zoppo, Antonio; Di Toro, Massimo; Inglima, Gianni; Glodariu, Tudor; La Commara, Marco; Maiolino, Concetta; Mazzocco, Marco; Pagano, Angelo; Piattelli, Paolo; Pirrone, Sara; Rizzo, Carmelo; Romoli, Mauro; Sandoli, Mario; Santonocito, Domenico; Sapienza, Piera; Signorini, Cosimo

    2008-01-01

    The prompt gamma ray emission was investigated in the 16A MeV energy region by means of the 36,40Ar+96,92Zr fusion reactions leading to a compound nucleus in the vicinity of 132Ce. We show that the prompt radiation, which appears to be still effective at such a high beam energy, has an angular distribution pattern consistent with a dipole oscillation along the symmetry axis of the dinuclear system. The data are compared with calculations based on a collective bremsstrahlung analysis of the reaction dynamics.

  19. Direct determination of Cd, Hg in liver and kidney by prompt gamma activation analysis

    International Nuclear Information System (INIS)

    The development of a method for in-vivo measurement of some elemental concentration in organs making use of prompt gamma activation analysis with the filtered neutron beam at the Dalat reactor is being carried out. In this paper we present primary results in research and development of an IVPGNAA facility at the Dalat reactor. Beside the description of experimental set-up, it consists of determination of thermal neutron flux distribution in phantom, and the evaluation of the detection limit and analytical sensitivity for Cd and Hg in the kidney and the liver. Discussions are given to improve the IVPGNAA facility in the future. (author)

  20. 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.

  1. Boron Analysis of Alga and Agar-Agar by Prompt Gamma-Ray Technique

    International Nuclear Information System (INIS)

    The purpose of this research is to develop Prompt Gamma-Ray Technique and to analyse boron concentration in Alga and Agar-Agar. The equipments were designed to find the suitable position of neutron source and detector and the suitable model of collimator, in order to attenuating background. After that, these equipments were used to determine the concentration of boron in Alga and Agar-Agar

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

    OpenAIRE

    Litaize O.; Regnier D.; Serot O.

    2013-01-01

    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-Fe...

  3. 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.

  4. 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...

  5. 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.)

  6. 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.

  7. 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

  8. 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)

  9. 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…

  10. 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).

  11. Isolated prompt photon production at CDF

    International Nuclear Information System (INIS)

    This note describes measurements of isolated prompt photon production at √s = 1.8 TeV using the CDF experiment. The measurements are compared to recent NLO QCD calculations, including recently obtained parton distribution functions. Qualitatively, the QCD calculation with the new parton distribution functions agrees better with the data than the previous parton distribution functions

  12. Isolated prompt photon production at CDF

    Energy Technology Data Exchange (ETDEWEB)

    Maas, P.A. [Wisconsin Univ., Madison, WI (United States); CDF Collaboration

    1992-11-01

    This note describes measurements of isolated prompt photon production at {radical}s = 1.8 TeV using the CDF experiment. The measurements are compared to recent NLO QCD calculations, including recently obtained parton distribution functions. Qualitatively, the QCD calculation with the new parton distribution functions agrees better with the data than the previous parton distribution functions.

  13. 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.

  14. 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

  15. Toward a New Evaluation of Neutron Standards

    Science.gov (United States)

    Carlson, A. D.; Pronyaev, V. G.; Capote, R.; Hale, G. M.; Hambsch, F.-J.; Kawano, T.; Kunieda, S.; Mannhart, W.; Nelson, R. O.; Neudecker, D.; Schillebeeckx, P.; Simakov, S.; Smith, D. L.; Talou, P.; Tao, X.; Wallner, A.; Wang, W.

    2016-02-01

    Measurements related to neutron cross section standards and certain prompt neutron fission spectra are being evaluated. In addition to the standard cross sections, investigations of reference data that are not as well known as the standards are being considered. Procedures and codes for performing this work are discussed. A number of libraries will use the results of this standards evaluation for new versions of their libraries. Most of these data have applications in neutron dosimetry.

  16. 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 ...

  17. 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…

  18. Integrated system of production of neutronics and photonics calculational constants. Volume 21, Part A. Maxwell-averaged reaction rates (sigma v-bar) for selecteed reactions between ions with atomic mass less than or equal to 11

    International Nuclear Information System (INIS)

    Maxwell-averaged reaction rates (sigma v-bar) are presented for 24 interactions between 1H, 2H, 3H, 3He, 4He, 6Li, 7Li, 10B, and 11B ions. The reactions rates are calculated by use of the evaluated data of the LLL Evaluated Nuclear Data Library (ENDL). 5 figures, 5 tables

  19. On Averaging Rotations

    DEFF Research Database (Denmark)

    Gramkow, Claus

    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...... natural approximations to the Riemannian metric, and that the subsequent corrections are inherient in the least squares estimation. Keywords: averaging rotations, Riemannian metric, matrix, quaternion...

  20. 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...

  1. 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...

  2. 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...... natural approximations to the Riemannian metric, and that the subsequent corrections are inherient in the least squares estimation. Keywords: averaging rotations, Riemannian metric, matrix, quaternion...

  3. 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 ...

  4. 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.

  5. 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.

  6. Gamma-Ray Burst Prompt Emission

    CERN Document Server

    Zhang, Bing

    2014-01-01

    The origin of gamma-ray burst (GRB) prompt emission, bursts of gamma-rays lasting from shorter than one second to thousands of seconds, remains not fully understood after more than 40 years of observations. The uncertainties lie in several open questions in the GRB physics, including jet composition, energy dissipation mechanism, particle acceleration mechanism, and radiation mechanism. Recent broad-band observations of prompt emission with Fermi sharpen the debates in these areas, which stimulated intense theoretical investigations invoking very different ideas. I will review these debates, and argue that the current data suggest the following picture: A quasi-thermal spectral component originating from the photosphere of the relativistic ejecta has been detected in some GRBs. Even though in some cases (e.g. GRB 090902B) this component dominates the spectrum, in most GRBs, this component either forms a sub-dominant "shoulder" spectral component in the low energy spectral regime of the more dominant "Band" co...

  7. A Monte Carlo simulation of prompt gamma emission from fission fragments

    International Nuclear Information System (INIS)

    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 carried out 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. (authors)

  8. 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.

  9. 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.

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

    Science.gov (United States)

    Regnier, D.; Litaize, O.; Serot, O.

    2013-03-01

    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.

  11. Development of prompt gamma activation analysis

    International Nuclear Information System (INIS)

    Application of prompt gamma-activation analysis to some environmental samples and NBS's standard reference materials were examined, using NBS reactor and the technique developed by the nuclear chemistry group of the University of Maryland. Concentration of several elements, Cd, B, S, Se, Sb, Zn, Ba, Cr, Cs, Co, Si, Hf, Ce, Yb, Lu, Th, Sc, Eu, Fe, Ta and Rb, were determined by both PGAA and INAA. (author)

  12. Are there 'prompt' like-sign dimuons

    International Nuclear Information System (INIS)

    From exposures of the CDHS detector at the CERN SPS we have obtained 367 μ-μ- events in neutrino beams and 73 μ+μ+ events in an antineutrino beam. The magnitude of a prompt like-sign signal has been controversial in the past and moreover could not be explained by known production mechanisms. A critical discussion of the experimental situation is given. We have tried to reduce the systematic uncertainties of previous experiments and to get more information on the dependence of the signal with energy and the muon momentum cut-off. This experiment yields a signal of 2.8sigma (2.4sigma) of prompt like-sign dimuon events in the case of neutrinos (antineutrinos). The rate to charged current events is of the order of 10-4 for psub(μ)>9 GeV and E>100 GeV. The prompt signal has all the properties expected from the production and decay of charm-anticharm events. The magnitude, however, is substantially higher than the prediction of perturbative QCD but lower than some other experiments. (orig.)

  13. Prompt GRB optical follow-up experiments

    Energy Technology Data Exchange (ETDEWEB)

    Park, H-S; Williams, G; Ables, E; Band, D; Barthelmy, S; Bionta, R; Cline, T; Gehrels, N; Hartmann, D; Hurley, K; Kippen, M; Nemiroff, R; Pereira, W; Porrata, R

    2000-11-13

    Gamma Ray Bursts (GRBs) are brief, randomly located, releases of gamma-ray energy from unknown celestial sources that occur almost daily. The study of GRBs has undergone a revolution in the past three years due to an international effort of follow-up observations of coordinates provided by Beppo/SAX and IPN GRB. These follow-up observations have shown that GRBs are at cosmological distances and interact with surrounding material as described by the fireball model. However, prompt optical counterparts have only been seen in one case and are therefore very rare or much dimmer than the sensitivity of the current instruments. Unlike later time afterglows, prompt optical measurements would provide information on the GRB progenitor. LOTIS is the very first automated and dedicated telescope system that actively utilizes the GRB Coordinates Network (GCN) and it attempts to measure simultaneous optical light curve associated with GRBs. After 3 years of running, LOTIS has responded to 75 GRB triggers. The lack of any optical signal in any of the LOTIS images places numerical limits on the surrounding matter density, and other physical parameters in the environment of the GRB progenitor. This paper presents LOTIS results and describes other prompt GRB follow-up experiments including the Super-LOTIS at Kitt Peak in Arizona.

  14. 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 ...

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. In situ Elemental Analysis of Ancient Objects Using Prompt Gamma-Ray Measurement Techniques

    International Nuclear Information System (INIS)

    Full text: In this research, measurement of prompt gamma-rays from neutron capture and inelastic scattering of neutrons was experimentally investigated to be used for in situ qualitative analysis of elements in ancient objects. A 1.85 GBq Am241/Be neutron source, a portable high purity germanium detector with a relative efficiency of 30 % and an Inspector 2000 spectrum analyzer connected to a portable microcomputer. In laboratory, 12 test specimens were analyzed including metals, chemicals, mortar, as well as Buddha images and a bronze bell. In the field, a Buddha image at Wat Naphramain in Ayuthaya Province was analyzed. The results indicated that the technique was capable of analysing some elements such as B, Al, Si, Cl, Ca, Cu, Fe and Pb but was not sensitive to some elements like Sn and Au

  1. 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.

  2. 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 to...

  3. 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).

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

    International Nuclear Information System (INIS)

    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). (author)

  5. High-sensitivity transuranic waste assay by simultaneous proton and thermal-neutron interrogation using an electron linear accelerator

    International Nuclear Information System (INIS)

    Simultaneous photon and neutron interrogation from electron linear accelerator pulses is used as the basis for a unique assay technique for transuranics. Both prompt and delayed neutrons from the induced fissions are counted on a single detection system, and the contributions from each interrogating flux are resolved. Detection limits (3 sigma) for 239Pu were estimated to be 3 mg for prompt fission neutrons and 6 mg for delayed neutrons. The technique also provides a clear distinction between fissile and fertile nuclides

  6. Covariant approximation averaging

    CERN Document Server

    Shintani, Eigo; Blum, Thomas; Izubuchi, Taku; Jung, Chulwoo; Lehner, Christoph

    2014-01-01

    We present a new class of statistical error reduction techniques for Monte-Carlo simulations. Using covariant symmetries, we show that correlation functions can be constructed from inexpensive approximations without introducing any systematic bias in the final result. We introduce a new class of covariant approximation averaging techniques, known as all-mode averaging (AMA), in which the approximation takes account of contributions of all eigenmodes through the inverse of the Dirac operator computed from the conjugate gradient method with a relaxed stopping condition. In this paper we compare the performance and computational cost of our new method with traditional methods using correlation functions and masses of the pion, nucleon, and vector meson in $N_f=2+1$ lattice QCD using domain-wall fermions. This comparison indicates that AMA significantly reduces statistical errors in Monte-Carlo calculations over conventional methods for the same cost.

  7. 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...

  8. 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)

  9. 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.)

  10. 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

  11. 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.

  12. 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.

  13. 78 FR 39063 - Prompt Payment Interest Rate; Contract Disputes Act

    Science.gov (United States)

    2013-06-28

    ... Fiscal Service Prompt Payment Interest Rate; Contract Disputes Act AGENCY: Bureau of the Fiscal Service..., the prompt payment interest rate is 1\\3/4\\ per centum per annum. ADDRESSES: Comments or inquiries may...). The Contract Disputes Act of 1978, Sec. 12, Public Law 95-563, 92 Stat. 2389, and the Prompt...

  14. 76 FR 82350 - Prompt Payment Interest Rate; Contract Disputes Act

    Science.gov (United States)

    2011-12-30

    ... Fiscal Service Prompt Payment Interest Rate; Contract Disputes Act AGENCY: Bureau of the Public Debt... on June 30, 2012, the prompt payment interest rate is 2 per centum per annum. ADDRESSES: Comments or...). The Contract Disputes Act of 1978, Sec. 12, Public Law 95-563, 92 Stat. 2389, and the Prompt...

  15. 77 FR 38888 - Prompt Payment Interest Rate; Contract Disputes Act

    Science.gov (United States)

    2012-06-29

    ... Fiscal Service Prompt Payment Interest Rate; Contract Disputes Act AGENCY: Bureau of the Public Debt... December 31, 2012, the prompt payment interest rate is 1\\3/4\\ per centum per annum. ADDRESSES: Comments or...). The Contract Disputes Act of 1978, Sec. 12, Public Law 95-563, 92 Stat. 2389, and the Prompt...

  16. 75 FR 37881 - Prompt Payment Interest Rate; Contract Disputes Act

    Science.gov (United States)

    2010-06-30

    ... Fiscal Service Prompt Payment Interest Rate; Contract Disputes Act AGENCY: Bureau of the Public Debt... December 31, 2010, the prompt payment interest rate is 3\\1/8\\ per centum per annum. ADDRESSES: Comments or...). The Contract Disputes Act of 1978, Sec. 12, Public Law 95-563, 92 Stat. 2389, and the Prompt...

  17. 77 FR 76624 - Prompt Payment Interest Rate; Contract Disputes Act

    Science.gov (United States)

    2012-12-28

    ... Fiscal Service Prompt Payment Interest Rate; Contract Disputes Act AGENCY: Bureau of the Public Debt... on June 30, 2013, the prompt payment interest rate is 1-3/8 per centum per annum. ADDRESSES: Comments...). The Contract Disputes Act of 1978, Sec. 12, Public Law 95-563, 92 Stat. 2389, and the Prompt...

  18. 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…

  19. 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)

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

    International Nuclear Information System (INIS)

    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.