Sample records for activation neutron spectra

  1. Modeling of Neutron Spectra Based on Activation Analysis

    NASA Astrophysics Data System (ADS)

    Jovancevic, N.; Fridman, M.; Daraban, L.; Hambsch, F.-J.; Oberstedt, S.; Hult, M.; Lutter, G.; Marissens, G.; Stroh, H.

    Safe and economical use of nuclear energy and particularly the development of GEN-IV reactors impose a better understanding of prompt neutron emission in fission, as well as of the fission process as such. Therefore, accurate measurements of the prompt fission neutron spectra (PFNS) are very important. In this work, we are testing the possibility to determine the PFNS by an activation method called DONA (DOsimetry and Spectroscopy using Neuron Activation) recently developed at IRMM (Wieslander et al., 2010, Lövestam et al., 2009). This type of modeling of the neutron spectra, based on the activation analysis, can provide new information about an old problem which still exists today, i.e. the discrepancy between measured integral and differential data (Capote et al., 2012). The problem is that the calculated average cross section for a certain neutron reaction, by using the differential experimental PFNS, in many cases cannot reproduce satisfactorily the integral measured cross section values. The modeling of the neutron spectra by the DONA technique was tested with the standard neutron spectrum of the spontaneous fission of 252Cf. We analyzed the sensitivity of the unfolding procedure to the initial neutron energy spectrum, the influence of the neutron scattering, the possibility of using different activation reactions and we also made an estimation of the lowest measurable neutron fluence rate.

  2. NaI detector neutron activation spectra for PGNAA applications

    PubMed

    Gardner; El; Zheng; Hayden; Mayo

    2000-10-01

    When NaI detectors are used in prompt gamma-ray neutron activation analysis devices, they are activated by neutrons that penetrate the detector. While thermal neutron filters like boron or lithium can be used to reduce this activation, it can never be completely eliminated by this approach since high energy neutrons can penetrate the detector and thermalize inside it. This activation results in the emission of prompt gamma rays from both the I and Na and the production of the radioisotopes 128I and 24Na that subsequently decay and emit their characteristic beta particles and gamma rays. The resulting three spectra represent a background for this measurement. An experimental method for obtaining these three spectra is described and results are reported for 2" x 2", 5" x 5", 6" x 6", and 1" x 6" NaI detectors using the thermal neutron beam of the NCSU PULSTAR nuclear reactor. In addition, Monte Carlo simulation programs have been developed and used for simulating these spectra. Good results have been obtained by the Monte Carlo method for the two radioisotope spectra, and it is anticipated that good results will also be obtained for the prompt gamma-ray spectrum when the I and Na coincidence schemes are known. PMID:11003483

  3. Evaporation neutron spectra

    Microsoft Academic Search

    V. Sidorov

    1962-01-01

    The neutron spectra produced in the bombardment or V, Co, and Ni targets ; by alpha particles at 11 to 20 Mev are measured using the time-of-flight method. ; The analysis of these spectra according to the statistical theory of nuclear ; reactions is performed with an electronic computer. The level density fanction ; type that gives optimal agreement with

  4. Measurement of neutron spectra in varied environments by the foil-activation method with arbitrary trials

    SciTech Connect

    Kelly, J.G.; Vehar, D.W.

    1987-12-01

    Neutron spectra have been measured by the foil-activation method in 13 different environments in and around the Sandia Pulsed Reactor, the White Sands Missile Range Fast Burst Reactor, and the Sandia Annular Core Research Reactor. The spectra were obtained by using the SANDII code in a manner that was not dependent on the initial trial. This altered technique is better suited for the determination of spectra in environments that are difficult to predict by calculation, and it tends to reveal features that may be biased out by the use of standard trial-dependent methods. For some of the configurations, studies have also been made of how well the solution is determined in each energy region. The experimental methods and the techniques used in the analyses are thoroughly explained. 34 refs., 51 figs., 40 tabs.

  5. Leading neutron spectra

    E-print Network

    A. B. Kaidalov; V. A. Khoze; A. D. Martin; M. G. Ryskin

    2006-05-27

    It is shown that the observation of the spectra of leading neutrons from proton beams can be a good probe of absorptive and migration effects. We quantify how these effects modify the Reggeized pion-exchange description of the measurements of leading neutrons at HERA. We are able to obtain a satisfactory description of all the features of these data. We also briefly discuss the corresponding data for leading baryons produced in hadron-hadron collisions.

  6. Coarse-scaling adjustment of fine-group neutron spectra for epithermal neutron beams in BNCT using multiple activation detectors

    NASA Astrophysics Data System (ADS)

    Liu, Yuan-Hao; Nievaart, Sander; Tsai, Pi-En; Liu, Hong-Ming; Moss, Ray; Jiang, Shiang-Huei

    2009-01-01

    In order to provide an improved and reliable neutron source description for treatment planning in boron neutron capture therapy (BNCT), a spectrum adjustment procedure named coarse-scaling adjustment has been developed and applied to the neutron spectrum measurements of both the Tsing Hua Open-pool Reactor (THOR) epithermal neutron beam in Taiwan and the High Flux Reactor (HFR) in The Netherlands, using multiple activation detectors. The coarse-scaling adjustment utilizes a similar idea as the well-known two-foil method, which adjusts the thermal and epithermal neutron fluxes according to the Maxwellian distribution for thermal neutrons and 1/ E distribution over the epithermal neutron energy region. The coarse-scaling adjustment can effectively suppress the number of oscillations appearing in the adjusted spectrum and provide better smoothness. This paper also presents a sophisticated 9-step process utilizing twice the coarse-scaling adjustment which can adjust a given coarse-group spectrum into a fine-group structure, i.e. 640 groups, with satisfactory continuity and excellently matched reaction rates between measurements and calculation. The spectrum adjustment algorithm applied in this study is the same as the well-known SAND-II.

  7. Mechanical approach to the neutrons spectra collimation and detection

    SciTech Connect

    Sadeghi, H.; Roshan, M. V. [Energy Engineering and Physics Department, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2014-11-15

    Neutrons spectra from most of known sources require being collimated for numerous applications; among them one is the Neutron Activation Analysis. High energy neutrons are collimated through a mechanical procedure as one of the most promising methods. The output energy of the neutron beam depends on the velocity of the rotating Polyethylene disks. The collimated neutrons are then measured by an innovative detection technique with high accuracy.

  8. Spectra and Neutron Dosimetry Inside a PET Cyclotron Vault Room

    SciTech Connect

    Vega-Carrillo, Hector Rene [Unidades Academicas: Estudios Nucleares e Ing. Electrica. Universidad Autonoma de Zacatecas, A.P. 336, 98000 Zacatecas, Zac. Mexico (Mexico); Mendez, Roberto [Universidad Europea Miguel de Cervantes, Valladolid (Spain); Iniguez, Maria Pilar [Facultad de Ciencias de la Universidad de Valladolid, Valladolid (Spain); Marti-Climent, Joseph; Penuelas, Ivan [Servicio de Medicina Nuclear, Clinica Universitaria de la Universidad de Navarra (Spain); Barquero, Raquel [Hospital Universitario Rio Hortega, Valladolid (Spain)

    2006-09-08

    The neutron field around a PET cyclotron was investigated during 18F radioisotope production with an 18 MeV proton beam. Pairs of thermoluminescent dosemeters, TLD600 and TLD700, were used as thermal neutron detector inside a Bonner Spheres Spectrometer to measure the neutron spectra at three different positions inside the cyclotron's vault room. Neutron spectra were also determined by Monte Carlo calculations. The hardest spectrum was observed in front of cyclotron target and the softest was noticed at the antipode of target. Neutron doses derived from the measured spectra vary between 11 and 377 mSv/{mu}A-h of proton integrated current, Doses were also measured with a single-moderator remmeter, with an active thermal neutron detector, whose response in affected by the radiation field in the vault room.

  9. Neutron Spectra in a 15 MV LINAC

    NASA Astrophysics Data System (ADS)

    Vega-Carrillo, H. R.; Chu, Wei-Han; Tung, Chuan-Jong; Lan, Jen-Hong

    2010-12-01

    Neutron spectra were calculated inside the treatment hall of a 15 MV LINAC, calculations were carried out using Monte Carlo methods. With a Bonner sphere spectrometer with pairs of thermoluminiscent dosimeters the neutron spectrum at 100 cm from the isocenter was measured and compared with the calculated spectrum. All the spectra in the treatment hall show the presence of evaporation and knock-on neutrons; also the room-return due to the hall features is shown. In the maze the large contribution are due to epithermal and thermal neutrons. A good agreement between the calculated and measured spectrum at 100 cm was noticed, from this comparison the differences are attributed to the water content in the concrete of the hall.

  10. Neutron Spectra in a 15 MV LINAC

    SciTech Connect

    Vega-Carrillo, H. R. [Unidad Academica de Estudios Nucleares de la Universidad Autonoma de Zacatecas. Apdo. Postal 336, 98000 Zacatecas, Zac. (Mexico); Chu, Wei-Han [National Tsing Hua University, Hsinchu, Taiwan (China); Tung, Chuan-Jong [Chan Gung University, Taiwan (China); Lan, Jen-Hong [Chan Gung Memorial Hospital-Kaohsiung Medical Center and National Kaohsiung University, Kaohsiung, Taiwan (China)

    2010-12-07

    Neutron spectra were calculated inside the treatment hall of a 15 MV LINAC, calculations were carried out using Monte Carlo methods. With a Bonner sphere spectrometer with pairs of thermoluminiscent dosimeters the neutron spectrum at 100 cm from the isocenter was measured and compared with the calculated spectrum. All the spectra in the treatment hall show the presence of evaporation and knock-on neutrons; also the room-return due to the hall features is shown. In the maze the large contribution are due to epithermal and thermal neutrons. A good agreement between the calculated and measured spectrum at 100 cm was noticed, from this comparison the differences are attributed to the water content in the concrete of the hall.

  11. Validation of aggregate delayed neutron spectra calculated from precursor data

    SciTech Connect

    Brady, M. C.; England, T. R. [Oak Ridge National Lab., TN (USA); ,

    1989-01-01

    An extensive reference library of delayed neutron data has been compiled which contains fission yields and branchings, delayed neutron emission probabilities, and spectra for 271 precursors. These data have been used to calculate the aggregate behavior of delayed neutrons following a fission event in 43 fissioning systems. Least-squares techniques were used to produce fitted decay constants and abundances in the conventional six-group formalism from these calculated activity curves. A consistent set of six-group spectra have also been calculated for each of the fissioning systems. Recent measurements at the University of Lowell have produced measured energy spectra for delayed neutrons following the thermal fission (T) of {sup 235}U and {sup 239}Pu, and the fast fission (F) of {sup 238}U. These measured spectra provide data that may be used to validate the precursor data base and the fitted six-group data. This summary presents results of this validation effort. Both the individual precursor data and the six-group data have been used to calculate aggregate equilibrium spectra for {sup 235}U(T), {sup 238}U(F), and {sup 239}Pu(T) via summation techniques. The important precursors in each case are identified, and the status of their data reviewed. 8 refs., 3 figs., 3 tabs.

  12. Theoretical Spectra of Unmagnetized Neutron Stars

    NASA Astrophysics Data System (ADS)

    Joss, Paul C.; Madej, Jerzy

    2001-09-01

    We have developed new models for the atmospheres of unmagnetized or weakly magnetized (B <= 1010 G) neutron stars with effective temperatures, Teff, in the range of 4× 106 K <= Teff <= 1× 107 K. Our model calculations include a full and accurate treatment of Compton scattering effects. We consider both pure hydrogen/helium atmospheres and atmospheres containing substantial amounts of iron (i.e., iron abundances at least as high as the solar value). Using our model atmospheres, we are able to determine the thermal X-ray emission spectrum of an unmagnetized neutron star as a function of Teff, surface gravity, and atmospheric chemical composition. We find, in particular, that the spectra of unmagnetized neutron stars with iron-rich atmospheres will feature absorption lines with complex structure that can, in principle, be at least partially resolved in observations that utilize the Chandra transmission gratings. We also find that the spectra of iron-rich atmospheres exhibit substantial flux deficits, relative to the spectra of hydrogen/helium atmospheres or simple blackbodies, at photon energies higher than the bound-free absorption edges of lithium-like and beryllium-like ions of iron at ~2 keV. This latter result provides a method of determining the presence and abundance of iron and/or other heavy elements in a neutron star atmosphere, without the need to resolve individual spectral lines. As described in a companion paper (Stage and Joss, these proceedings), we are currently using our results to fit Chandra observations of the point source in Cassiopeia A and other possible cases of thermal radiation by weakly magnetized neutron stars. This work was supported in part by the National Aeronautics and Space Administration under contract NAS8-38249 and by the Polish Committee for Scientific Research under grant No. 2 P03D 013 19.

  13. Neutron Spectra and H*(10) in a 15 MV Linac

    SciTech Connect

    Benites, J. [Centro Estatal de Cancerologia de Nayarit-SSN-Mexico, Av. Enfermeria s/n, Col. Fray Junipero Serra, 63000 Tepic, Nayarit (Mexico); Alumno del Posgrado en CBAP, Universidad Autonoma de Nayarit, Carretera Tepic-Compostela km9. C.P. 63780. Xalisco-Nayarit-Mexico (Mexico); Vega-Carrillo, H. R.; Hernandez-Davila, V. M. [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Apdo. Postal 336, 98000 Zacatecas, Zac. Mexico (Mexico); Rivera, T. [CICATA-IPN, Unidad Legaria, Mexico city (Mexico); Carrillo, A.; Mondragon, R. [Centro Estatal de Cancerologia de Nayarit-SSN-Mexico, Av. Enfermeria s/n, Col. Fray Junipero Serra, 63000 Tepic, Nayarit (Mexico)

    2010-12-07

    Neutron spectra and the ambient dose equivalent were calculated inside the bunker of a 15 MV Varian linac model CLINAC iX. Calculations were carried out using Monte Carlo methods. Neutron spectra in the vicinity of isocentre show the presence of evaporation and knock-on neutrons produced by the source term, while epithermal and thermal neutron remain constant regardless the distance respect to isocentre, due to room return. Along the maze neutron spectra becomes softer as the detector moves along the maze. The ambient dose equivalent is decreased but do not follow the 1/r{sup 2} rule due to changes in the neutron spectra.

  14. Arsenic activation neutron detector

    DOEpatents

    Jacobs, Eddy L. (Albuquerque, NM)

    1981-01-01

    A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5 Mev neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.

  15. Arsenic activation neutron detector

    DOEpatents

    Jacobs, E.L.

    1980-01-28

    A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5-MeV neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.

  16. NEUTRON ACTIVATION CROSS SECTIONS

    Microsoft Academic Search

    J. A. Miskel; K. V. Marsh; M. Lindner; R. J. Nagle

    1959-01-01

    The (n, ) activation cross sections of several nuclides were measured ; as a function of neutron energy. The neutron energy range covered was from 31 ; kev to 6 Mev. The nuclides studied were Hf¹⁸°, Ta¹⁸¹,W¹⁸⁶,Au\\/; sup 197\\/, and Th\\/sup 232. (auth)

  17. MEASUREMENT OF THERMAL NEUTRON SPECTRA IN BORIC ACID SOLUTIONS

    Microsoft Academic Search

    E. Ya. Doilnitsyn; A. G. Novikov

    1962-01-01

    Contradictory data are reported in the literature on the thermal neutron ; spectra of aqueous solutions containing an absorber. This problem was studied by ; exposing boric acid solutions in water to the neutron beam of the GraphiteWater ; Reactor. The experimental results were found to agree well with the as yet ; unpublished theoretical values, calculated by G. I.

  18. Eigenvalue-dependent neutron energy spectra: Definitions, analyses, and applications

    Microsoft Academic Search

    D. G. Cacuci; Y. Ronen; Z. Shayer; J. J. Wagschal; Y. Yeivin

    1982-01-01

    A general qualitative analysis of spectral effects that arise from solving the kappa-, ..cap alpha..-, ..gamma..-, and sigma-eigenvalue formulations of the neutron transport equation for nuclear systems that deviate (to first order) from criticality is presented. Hierarchies of neutron spectra softness are established and expressed concisely in terms of the newly introduced spatialdependent local spectral indices for the core and

  19. H*(10) and neutron spectra around linacs

    Microsoft Academic Search

    Hector Rene Vega-Carrillo; Arturo Ortíz-Hernandez; Victor Martin Hernandez-Davila; Berenice Hernández-Almaraz; Teodoro Rivera Montalvo

    2010-01-01

    Neutron spectrum and ambient dose equivalent has been measured around two 10 MV linear accelerators. Measurements were carried\\u000a out in Mevatron and Primus model linacs, both made by Siemens. Main differences between those models are the beam collimator\\u000a and the vault room. Here, Bonner sphere spectrometer with a passive thermal neutron detector has been utilized to measure\\u000a the neutron spectrum inside

  20. Spectra of neutrons from a beam-driven fusion source

    NASA Astrophysics Data System (ADS)

    Goncharov, P. R.

    2015-06-01

    Semianalytical calculations of fusion neutron spectra in case of the presence of substantial suprathermal tails in fuel nuclei velocity distributions have been implemented using two different approaches. Numerical techniques are described. Results for a variety of isotropic and anisotropic distributions of suprathermal fuel nuclei are presented. Verification of calculated fusion product spectra has been performed using several methods.

  1. Measurement of inclusive neutron spectra at the ISR

    Microsoft Academic Search

    J. Engler; B. Gibbard; W. Isenbeck; F. Moennig; J. Moritz; K. Pack; K. H. Schmidt; D. Wegener; W. Bartel; W. Flauger; H. Schopper

    1975-01-01

    With a total absorption counter, inclusive neutron spectra have been measured at four ISR energies and at angles of 20, 66 and 119 mrad. The spectra show scaling behavior in the variables x and p?. Pion exchange is found to be important at large x values.

  2. Fission neutron spectra measurements at LANSCE - status and plans

    SciTech Connect

    Haight, Robert C [Los Alamos National Laboratory; Noda, Shusaku [Los Alamos National Laboratory; Nelson, Ronald O [Los Alamos National Laboratory; O' Donnell, John M [Los Alamos National Laboratory; Devlin, Matt [Los Alamos National Laboratory; Chatillon, Audrey [CEA-FRANCE; Granier, Thierry [CEA-FRANCE; Taieb, Julien [CEA-FRANCE; Laurent, Benoit [CEA-FRANCE; Belier, Gilbert [CEA-FRANCE; Becker, John A [LLNL; Wu, Ching - Yen [LLNL

    2009-01-01

    A program to measure fission neutron spectra from neutron-induced fission of actinides is underway at the Los Alamos Neutron Science Center (LANSCE) in a collaboration among the CEA laboratory at Bruyeres-le-Chatel, Lawrence Livermore National Laboratory and Los Alamos National Laboratory. The spallation source of fast neutrons at LANSCE is used to provide incident neutron energies from less than 1 MeV to 100 MeV or higher. The fission events take place in a gas-ionization fission chamber, and the time of flight from the neutron source to that chamber gives the energy of the incident neutron. Outgoing neutrons are detected by an array of organic liquid scintillator neutron detectors, and their energies are deduced from the time of flight from the fission chamber to the neutron detector. Measurements have been made of the fission neutrons from fission of {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu. The range of outgoing energies measured so far is from 1 MeV to approximately 8 MeV. These partial spectra and average fission neutron energies are compared with evaluated data and with models of fission neutron emission. Results to date will be presented and a discussion of uncertainties will be given in this presentation. Future plans are to make significant improvements in the fission chambers, neutron detectors, signal processing, data acquisition and the experimental environment to provide high fidelity data including mea urements of fission neutrons below 1 MeV and improvements in the data above 8 MeV.

  3. Neutron Spectra and Dose Equivalent Inside Nuclear Power Reactor Containment

    SciTech Connect

    Aldrich, J. M.

    1981-08-01

    This study was conducted to determine absorbed dose, dose-equivalent rates, and neutron spectra inside containment at nuclear power plants. We gratefully acknowledge funding support by the Nuclear Regulatory Commission. The purpose of this study is: 1) measure dose-equivalent rates with various commercial types of rem meters, such as the Snoopy and Rascal, and neutron absorbed dose rates with a tissue-equivalent proportional counter 2) determine neutron spectra using the multi sphere or Bonner sphere technique and a helium-3 spectrometer 3) compare several types of personnel neutron dosimeter responses such as NTA film, polycarbonates, TLD albedo, and a recently introduced proton recoil track etch dosimeter, and CR-39. These measurements were made inside containments of pressurized water reactors (PWRs) and outside containment penetrations of boiling water reactors (BWRs) operating at full power. The neutron spectral information, absorbed dose. and dose-equivalent measurements are needed for proper interpretation of instrument and personnel dosimeter responses.

  4. Physical basis for prompt-neutron activation analysis

    SciTech Connect

    Chrien, R.E.

    1982-01-01

    The technique called prompt ..gamma..-ray neutron activation analysis has been applied to rapid materials analysis. The radiation following the neutron radiation capture is prompt in the sense that the nuclear decay time is on the order of 10/sup -15/ second, and thus the technique is not strictly activation, but should be called radiation neutron capture spectroscopy or neutron capture ..gamma..-ray spectroscopy. This paper reviews the following: sources and detectors, theory of radiative capture, nonstatistical capture, giant dipole resonance, fast neutron capture, and thermal neutron capture ..gamma..-ray spectra. 14 figures.

  5. NEUTRON-SPECTRA CALCULATIONS FOR RADIATION-DAMAGE STUDIES

    Microsoft Academic Search

    R. E. Dahl; H. H. Yoshikawa

    1963-01-01

    Fast-neutron spectra were computed using three different codes: GNU-II, ; HFN, GE -HAPO-S-X. Significant diffurences in spectra were seen as codes with ; varying degrees of refinement were used. GE -RAPO-S-X was chosen for calculating ; cross section values and testing damage models because of its greater accuracy ; and wider applicability. The calculations illustrate spectral differences ; existing at

  6. Determination of Godiva`s effective delayed neutron fraction using newly calculated delayed neutron spectra

    SciTech Connect

    Spriggs, G.D.; Campbell, J.M. [Los Alamos National Lab., NM (United States); Busch, R.D. [Univ. of New Mexico, Albuquerque, NM (United States)

    1999-09-01

    When calculating the effective delayed neutron fraction {beta}{sub eff} for a given reactor system, the assumed delayed neutron group spectra and the assumed number of delayed neutrons born per fission {nu}{sub d} can have a major impact on the final value. Over the years, the recommended values for the delayed neutron spectra and for {nu}{sub d} have slowly changed. To ascertain whether or not these changes have increased the accuracy of {beta}{sub eff} calculations in fast {sup 235}U systems, the authors have reevaluated {beta}{sub eff} for the benchmark system Godiva-I using newly calculated delayed neutron spectra and Tuttle`s recommended values of {nu}{sub d} for both {sup 235}U and {sup 238}U.

  7. Thermal Neutron Activation Cross Sections

    Microsoft Academic Search

    Leo Seren; Herbert N. Friedlander; Solomon H. Turkel

    1947-01-01

    The activation method of measuring slow neutron cross sections is discussed, in connection with the survey made at Argonne Laboratory. A table is given listing 131 activation cross sections of 65 elements and properties of the radio isotopes produced.

  8. Neutron and gamma-ray spectra of 239PuBe and 241AmBe

    Microsoft Academic Search

    Héctor René Vega-Carrillo; Eduardo Manzanares-Acuña; Ana Mar??a Becerra-Ferreiro; Aureliano Carrillo-Nuñez

    2002-01-01

    Neutron and gamma-ray spectra of 239PuBe and 241AmBe were measured and their dosimetric features were calculated. Neutron spectra were measured using a multisphere neutron spectrometer with a 6LiI(Eu) scintillator. The 239PuBe neutron spectrum was measured in an open environment, while the 241AmBe neutron spectrum was measured in a closed environment. Gamma-ray spectra were measured using a NaI(Tl) scintillator using the

  9. Fast neutron activation dosimetry with TLDS

    Microsoft Academic Search

    D. W. Pearson; P. R. Moran

    1975-01-01

    Fast neutron activation using threshold reactions is the only neutron dosimetry method which offers complete discrimination against gamma-rays and preserves some information about the neutron energy. Conventional activation foil technique requires sensitive radiation detectors to count the decay of the neutron induced activity. For extensive measurements at low neutron fluences, vast outlays of counting equipment are required. TL dosimeters are

  10. HALOGEN DELAYED-NEUTRON ACTIVITIES

    Microsoft Academic Search

    A. F. Stehney; G. J. Perlow

    1958-01-01

    Fission-product bromine was separated rapidiy from fission-product ; iodine and the neutron activity of either species was counted. This was done by ; irradiating with thermal neutrons a solution of U²³⁵ containing the ; reagents for transforming the unwanted halogen into nonvolatile form. Air ; containing some of the desired halogen as carrier is swept rapidiy through the ; solution

  11. PINO - a tool for simulating neutron spectra resulting from the 7Li(p,n) reaction

    E-print Network

    R. Reifarth; M. Heil; F. Käppeler; R. Plag

    2013-10-06

    The 7Li(p,n) reaction in combination with a 3.7 MV Van de Graaff accelerator was routinely used at FZK to perform activation as well as time-of-flight measurements with neutrons in the keV-region. Planned new setups with much higher proton currents like SARAF and FRANZ and the availability of liquid-lithium target technology will trigger a renaissance of this method. A detailed understanding of the neutron spectrum is not only important during the planning phase of an experiment, but also during for the analysis of activation experiments. Therefore, the Monte-Carlo based program PINO (Protons In Neutrons Out) was developed, which allows the simulation of neutron spectra considering the geometry of the setup and the proton-energy distribution.

  12. The study of neutron spectra in water bath from Pb target irradiated by 250MeV/u protons

    E-print Network

    Yanyan Li; Xueying Zhang; Yongqin Ju; Fei Ma; Hongbin Zhang; Liang Chen; Honglin Ge; Peng Luo; Bin Zhou; Yanbin Zhang; Jianyang Li; Junkui Xu; Songlin Wang; Yongwei Yang; Lei Yang

    2014-09-05

    The spallation neutrons were produced by the irradiation of Pb with 250 MeV protons. The Pb target was surrounded by water which was used to slow down the emitted neutrons. The moderated neutrons in the water bath were measured by using the resonance detectors of Au, Mn and In with Cd cover. According to the measured activities of the foils, the neutron flux at different resonance energy were deduced and the epithermal neutron spectra were proposed. Corresponding results calculated with the Monte Carlo code MCNPX were compared with the experimental data to check the validity of the code.

  13. Neutron source images and spectra to guide neutron diagnostics specifications for the National Ignition Facility

    SciTech Connect

    Sweezy, J. E.; Wilson, D. C.; Bradley, P. A.; Grim, G. P.; Choi, C. K.; Coggeshall, J. C.; Wilde, C. H.; Forster, R. A.; Russell, R. D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2006-10-15

    Both neutron images and spectra will diagnose ignition implosions at the National Ignition Facility. From the integrated Hohlraum and capsule calculations of copper-doped beryllium capsules using {approx}1 MJ of laser energy we have postprocessed neutron spectra and both energy-gated and time integrated neutron images displaying the observable consequences of two-dimensional Hohlraum asymmetries. If low signal precludes multiple down scattered images, we suggest a 6-12 MeV gate. With asymmetries, it is noted that the neutron yield, spectra, and images vary with observation direction. The yield varies only several percent when observed at different angles. Since most asymmetries are expected about the Hohlraum axis, a perpendicular view has the highest priority. The next most informative view would be along the Hohlraum axis, but may be precluded by target chamber structures. We present images at the available port angles and discuss their utility. To facilitate detailed diagnostic simulations with real pinhole geometries or penumbral apertures, we offer a compact disk containing neutron spectra and gated images from various integrated calculations.

  14. Neutron fluences and energy spectra in the Cosmos-2044 biosatellite orbit

    NASA Technical Reports Server (NTRS)

    Dudkin, V. E.; Akopova, A. B.; Melkumyan, L. V.; Benton, E. V.; Frank, A. L.

    1992-01-01

    Joint Soviet-American measurements of the neutron component of space radiation (SR) were carried out during the flight of the Soviet biosatellite Cosmos-2044. Neutron flux densities and differential energy spectra were measured inside and on the external surface of the spacecraft. Three energy intervals were employed: thermal (En < or = 0.2 eV), resonance (0.2 eV < En < 1.0 MeV) and fast (En > or = 1.0 MeV) neutrons. The first two groups were measured with U.S. 6LiF detectors, while fast neutrons were recorded both by U.S. fission foils and Soviet nuclear emulsions. Estimations were made of the contributions to absorbed and equivalent doses from each neutron energy interval and a correlation was presented between fast neutron fluxes, measured outside the satellite, and the phase of solar activity (SA). Average dose equivalent rates of 0.018 and 0.14 mrem d-1 were measured for thermal and resonance neutrons, respectively, outside the spacecraft. The corresponding values for fast neutrons were 3.3 (U.S.) and 1.8 (U.S.S.R.) mrem d-1. Inside the spacecraft, a value of 3.5 mrem d-1 was found.

  15. Neutron influences and energy spectra in the Cosmos-2044 biosatellite orbit

    NASA Technical Reports Server (NTRS)

    Dudkin, V. E.; Potapov, Yu. V.; Akopova, A. B.; Melkumyan, L. V.; Rshtuni, Sh. B.; Benton, E, V.; Frank, A. L.

    1995-01-01

    Joint Soviet-American measurements of the neutron component of space radiation (SR) were carried out during the flight of the Soviet biosatellite Cosmos-2044. Neutron flux densities and differential energy spectra were measured inside and on the external surface of the spacecraft. Three energy intervals were employed: thermal (E(sub n) less than or equal to 0.2 eV), resonance (0.2 eV less than E(sub n) less than 1.0 MeV) and fast (E(sub n) greater than or equal to 1.0 MeV) neutrons. The first two groups were measured with U.S. (6)LiF detectors, while fast neutrons were recorded both by U.S. fission foils and Soviet nuclear emulsions. Estimations were made of the contributions to absorbed and equivalent doses from each neutron energy interval and a correlation was presented between fast neutron fluxes, measured outside the satellite, and the phase of solar activity (SA). Average dose equivalent rates of 0.018 and 0.14 mrem d(exp -1) were measured for thermal and resonance neutrons, respectively, outside the spacecraft. The corresponding values for fast neutrons were 3.3 (U.S.) and 1.8 (U.S.S.R.) mrem d(exp -1). Inside the spacecraft, a value of 3.5 mrem d(exp -1) was found.

  16. Neutron-Activation Cross Sections

    Microsoft Academic Search

    J. A. Miskel; K. V. Marsh; M. Lindner; R. J. Nagle

    1962-01-01

    Neutron-activation cross sections have been measured for five target nuclei, Hf180, Ta181, W186, Au197, and Th232, over a neutron energy range from 0.030 to 4.0 MeV. The experimental results are compared with values calculated from the statistical theory of nuclear reactions. Values of the constant Cn in the approximate level density formula pn=Cnexp[2(aE)12] are obtained for these isotopes from a

  17. Improved Fission Neutron Data Base for Active Interrogation of Actinides

    SciTech Connect

    Pozzi, Sara; Czirr, J. Bart; Haight, Robert; Kovash, Michael; Tsvetkov, Pavel

    2013-11-06

    This project will develop an innovative neutron detection system for active interrogation measurements. Many active interrogation methods to detect fissionable material are based on the detection of neutrons from fission induced by fast neutrons or high-energy gamma rays. The energy spectrum of the fission neutrons provides data to identify the fissionable isotopes and materials such as shielding between the fissionable material and the detector. The proposed path for the project is as follows. First, the team will develop new neutron detection systems and algorithms by Monte Carlo simulations and bench-top experiments. Next, They will characterize and calibrate detection systems both with monoenergetic and white neutron sources. Finally, high-fidelity measurements of neutron emission from fissions induced by fast neutrons will be performed. Several existing fission chambers containing U-235, Pu-239, U-238, or Th-232 will be used to measure the neutron-induced fission neutron emission spectra. The challenge for making confident measurements is the detection of neutrons in the energy ranges of 0.01 – 1 MeV and above 8 MeV, regions where the basic data on the neutron energy spectrum emitted from fission is least well known. In addition, improvements in the specificity of neutron detectors are required throughout the complete energy range: they must be able to clearly distinguish neutrons from other radiations, in particular gamma rays and cosmic rays. The team believes that all of these challenges can be addressed successfully with emerging technologies under development by this collaboration. In particular, the collaboration will address the area of fission neutron emission spectra for isotopes of interest in the advanced fuel cycle initiative (AFCI).

  18. NEUTRON-ACTIVATION CROSS SECTIONS

    Microsoft Academic Search

    J. A. Miskel; K. V. Marsh; M. Lindner; R. J. Nagle

    1961-01-01

    Neutron-activation cross sections for Hf¹⁸°, Ta¹⁸¹, W\\/sup ; 186\\/ Au¹⁹⁷, and Th²³² were measured. The results were compared ; with those calculated using the statistical theory of nuclear reactions and with ; resuits obtained by other investigators. (J.R.D.);

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

    SciTech Connect

    Kroc, T.K.; /Fermilab

    2009-10-01

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

  20. Six-group decomposition of composite delayed neutron spectra from sup 235 U fission

    SciTech Connect

    Villani, M.F.; Couchell, G.P.; Haghighi, M.H.; Pullen, D.J.; Schier, W.A.; Sharfuddin, Q. (Univ. of Massachusetts Lowell, Dept. of Physics and Applied Physics, Lowell, MA (US))

    1992-08-01

    In this paper, a constrained least-squares method is developed for deducing six-group delayed neutron energy spectra from composite spectra measured at six or more delay time intervals following fission. The constraining condition is chosen to yield stable solutions that also provide good fits to the measured spectra. The method is applied to previously measured composite spectra of {sup 235}U to obtain six-group delayed neutron energy spectra. The solutions are unique for a large range of constraint spectra. The dependence of the solutions on the choice of six-group parameters {beta} {lambda} is also examined.

  1. Neutron Spectra from Intermediate-Energy Nucleus-Nucleus Reactions

    E-print Network

    Hiroshi Iwase; Yoshiyuki Iwata; Takashi Nakamura; Konstantin Gudima; Stepan Mashnik; Arnold Sierk; Richard Prael

    2005-01-26

    Double-differential cross sections of neutron production at angles from 0 to 110 degrees from many reactions induced by light and medium nuclei on targets from 12-C to 208-Pb, at several incident energies from 95 to 600 MeV/A have been measured recently at the Institute of Physical and Chemical Research (RIKEN) Ring Cyclotron in Japan and at the Heavy-Ion Medical Accelerator of the National Institute of Radiological Science in Chiba, Japan using the time-of-flight technique. We have analyzed all these new measurements using the Quantum Molecular Dynamics (QMD) model, the Oak Ridge intranuclear cascade model HIC, the ISABEL intranuclear cascade model from LAHET, and the Los Alamos version of the Quark-Gluon String Model code LAQGSM03. On the whole, all four models used here describe reasonably well most of the measured neutron spectra, although different models agree differently with data from specific reactions and some serious discrepances are observed for some reactions. We present here some illustrative results from our study, discuss possible reasons for some of the observed discrepancies and try to outline ways to further improve the tested codes in order to address these problems.

  2. Prompt fission neutron spectra of n+235U above the (n,nf) fission threshold

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    Calculations of prompt fission neutron spectra (PFNS) from the 235U(n, f) reaction were performed with a semi-empirical method for En = 7.0 and 14.7 MeV neutron energies. The total PFNS were obtained as a superposition of (n,xnf) pre-fission neutron spectra and post-fission spectra of neutrons which were evaporated from fission fragments, and these two kinds of spectra were taken as an expression of the evaporation spectrum. The contributions of (n,xnf) fission neutron spectra on the calculated PFNS were discussed. The results show that emission of one or two neutrons in the (n,nf) or (n,2nf) reactions influences the PFNS shape, and the neutron spectra of the (n,xnf) fission-channel are soft compared with the neutron spectra of the (n,f) fission channel. In addition, analysis of the multiple-chance fission component showed that second-chance fission dominates the PFNS with an incident neutron energy of 14.7 MeV whereas first-chance fission dominates the 7 MeV case. Supported by National Natural Science Foundation of China (11205246, 91126010, U1230127, 91226102), IAEA CRP (15905), and Defense Industrial Technology Development Program (B0120110034)

  3. Search for an energy dependence in /sup 235/U delayed neutron spectra

    SciTech Connect

    Sharfuddin, Q.; Schier, W.A.; Tanczyn, R.S.; Pullen, D.J.; Haghighi, M.H.; Fisteag, L.; Couchell, G.P.

    1988-04-01

    A sensitive search for a dependence of composite (aggregate) delayed neutron spectra on the energy of neutrons inducing fission of /sup 235/U was performed for eight nearly contiguous delay time intervals between 0.17 to 85.5 s. The experimental arrangement combined a helium jet and tape transfer system with a beta-neutron time-of-flight spectrometer. Thermal and fast neutron measurements were performed successively. Results are compared with the spectra derived from individual precursor data complemented by theoretical estimates of missing spectra.

  4. Measurements and parameterization of neutron energy spectra from targets bombarded with 120 GeV protons

    NASA Astrophysics Data System (ADS)

    Kajimoto, T.; Shigyo, N.; Sanami, T.; Iwamoto, Y.; Hagiwara, M.; Lee, H. S.; Soha, A.; Ramberg, E.; Coleman, R.; Jensen, D.; Leveling, A.; Mokhov, N. V.; Boehnlein, D.; Vaziri, K.; Sakamoto, Y.; Ishibashi, K.; Nakashima, H.

    2014-10-01

    The energy spectra of neutrons were measured by a time-of-flight method for 120 GeV protons on thick graphite, aluminum, copper, and tungsten targets with an NE213 scintillator at the Fermilab Test Beam Facility. Neutron energy spectra were obtained between 25 and 3000 MeV at emission angles of 30°, 45°, 120°, and 150°. The spectra were parameterized as neutron emissions from three moving sources and then compared with theoretical spectra calculated by PHITS and FLUKA codes. The yields of the theoretical spectra were substantially underestimated compared with the yields of measured spectra. The integrated neutron yields from 25 to 3000 MeV calculated with PHITS code were 16-36% of the experimental yields and those calculated with FLUKA code were 26-57% of the experimental yields for all targets and emission angles.

  5. Effect of the preequilibrium process upon fast neutron fission spectra from 238U

    Microsoft Academic Search

    T. Kawano; T. Ohsawa; M. Baba; T. Nakagawa

    2001-01-01

    A preequilibrium process for the prefission neutron which is emitted before scission is calculated with the model of Feshbach, Kerman, and Koonin. A forward-peaked angular distribution of the neutron emission from 238U bombarded by 14 and 18 MeV neutrons is expressed with the statistical multistep compound process and the one-step direct process. The fission neutron energy spectra are calculated with

  6. Study of neutron spectra in a water bath from a Pb target irradiated by 250 MeV protons

    NASA Astrophysics Data System (ADS)

    Li, Yan-Yan; Zhang, Xue-Ying; Ju, Yong-Qin; Ma, Fei; Zhang, Hong-Bin; Chen, Liang; Ge, Hong-Lin; Wan, Bo; Luo, Peng; Zhou, Bin; Zhang, Yan-Bin; Li, Jian-Yang; Xu, Jun-Kui; Wang, Song-Lin; Yang, Yong-Wei; Yang, Lei

    2015-04-01

    Spallation neutrons were produced by the irradiation of Pb with 250 MeV protons. The Pb target was surrounded by water which was used to slow down the emitted neutrons. The moderated neutrons in the water bath were measured by using the resonance detectors of Au, Mn and In with a cadmium (Cd) cover. According to the measured activities of the foils, the neutron flux at different resonance energies were deduced and the epithermal neutron spectra were proposed. Corresponding results calculated with the Monte Carlo code MCNPX were compared with the experimental data to check the validity of the code. The comparison showed that the simulation could give a good prediction for the neutron spectra above 50 eV, while the finite thickness of the foils greatly effected the experimental data in low energy. It was also found that the resonance detectors themselves had great impact on the simulated energy spectra. Supported by National Natural Science Foundation and Strategic Priority Research Program of the Chinese Academy of Sciences (11305229, 11105186, 91226107, 91026009, XDA03030300)

  7. Neutron and gamma dose and spectra measurements on the Little Boy replica

    SciTech Connect

    Hoots, S.; Wadsworth, D.

    1984-06-01

    The radiation-measurement team of the Weapons Engineering Division at Lawrence Livermore National Laboratory (LLNL) measured neutron and gamma dose and spectra on the Little Boy replica at Los Alamos National Laboratory (LANL) in April 1983. This assembly is a replica of the gun-type atomic bomb exploded over Hiroshima in 1945. These measurements support the National Academy of Sciences Program to reassess the radiation doses due to atomic bomb explosions in Japan. Specifically, the following types of information were important: neutron spectra as a function of geometry, gamma to neutron dose ratios out to 1.5 km, and neutron attenuation in the atmosphere. We measured neutron and gamma dose/fission from close-in to a kilometer out, and neutron and gamma spectra at 90 and 30/sup 0/ close-in. This paper describes these measurements and the results. 12 references, 13 figures, 5 tables.

  8. New experimental system for measuring composite delayed-neutron spectra following fission

    NASA Astrophysics Data System (ADS)

    Schier, W. A.; Couchell, G. P.; Pullen, D. J.; Sampas, N. M.; Ciarcia, C. A.; Haghighi, M. H.; Sharfuddin, Q.; Tanczyn, R. S.

    1984-12-01

    We describe a new experimental approach for measuring composite delayed-neutron spectra as a function of delay time following fission. Fission fragments are transported from the fission chamber to a low background counting room by helium jet and tape transport systems. A ?-neutron time-of-flight spectrometer incorporating both 6Li-glass and Pilot U scintillators is used to measure the spectra in the neutron energy range 10-2000 keV. Delay times can be varied from 0.17 s to several minutes. Fission is induced with either thermal or fast neutrons.

  9. Neutron spectra at two beam ports of a TRIGA Mark III reactor loaded with HEU fuel.

    PubMed

    Vega-Carrillo, H R; Hernández-Dávila, V M; Aguilar, F; Paredes, L; Rivera, T

    2014-01-01

    The neutron spectra have been measured in two beam ports, one radial and another tangential, of the TRIGA Mark III nuclear reactor from the National Institute of Nuclear Research in Mexico. Measurements were carried out with the reactor core loaded with high enriched uranium fuel. Two reactor powers, 5 and 10 W, were used during neutron spectra measurements using a Bonner sphere spectrometer with a (6)LiI(Eu) scintillator and 2, 3, 5, 8, 10 and 12 in.-diameter high-density polyethylene spheres. The neutron spectra were unfolded using the NSDUAZ unfolding code. For each spectrum total flux, mean energy and ambient dose equivalent were determined. Measured spectra show fission, epithermal and thermal neutrons, being harder in the radial beam port. PMID:23746708

  10. Spectra

    NSDL National Science Digital Library

    The Exploratorium

    2012-06-26

    Learners construct a spectroscope out of a shoe box or mailing tube, diffraction grating, and other simple materials. They then use their spectroscope to observe spectra, the colors that make up light. Learners compare the spectra of various light sources. Use this activity to introduce learners to basic principles of light and color. Also, look at a related page about auroras to understand how distinguishing spectra of different atoms helps scientists understand the universe.

  11. Leakage neutron spectra from spherical samples with a Pu–Be source

    Microsoft Academic Search

    I ElAgib; J Csikai; J Jordanova; L Oláh

    1999-01-01

    Leakage neutron spectra from a Pu–Be source placed in the center of a 30 cm diameter sphere filled with water, paraffin oil, SiO2 and river sand were measured using a pulse height response spectrometer (PHRS) in the 1.4–12.0 MeV energy range. The measured leakage neutron spectra have been compared with the calculated results obtained by the three dimensional Monte Carlo

  12. Calculation verification of the utilization of LR-0 for reference neutron spectra

    NASA Astrophysics Data System (ADS)

    Ján, Mil?ák; Michal, Koš?ál; Marie, Švadlenková; Michal, Koleška; Vojt?ch, Rypar

    2014-11-01

    Well-defined neutron spectrum is crucial for calibration and testing of detectors for spectrometry and dosimetry purposes. As a possible source of neutrons nuclear reactors can be utilized. In reactor core most of the neutrons are originated from fission and neutron spectra is usually some form of moderated spectra of fast neutrons. The reactor LR-0 is an experimental light-water zero-power pool-type reactor originally designed for research of the VVER type reactor cores, spent-fuel storage lattices and benchmark experiments. The main reactor feature that influences the performance of experiments is the flexible arrangement of the core. Special types of the possible core arrangements on the reactor LR-0 can provide different neutron spectra in special experimental channels. These neutron spectra are modified by inserting different materials around the channel and whole core is driven by standard fuel assemblies. Fast, epithermal or thermal spectra can be simulated using graphite, H2O, D2O insertions, air, Cd foils or fuel with different enrichment.

  13. Calculated /alpha/-induced thick target neutron yields and spectra, with comparison to measured data

    SciTech Connect

    Wilson, W.B.; Bozoian, M.; Perry, R.T.

    1988-01-01

    One component of the neutron source associated with the decay of actinide nuclides in many environments is due to the interaction of decay /alpha/ particles in (/alpha/,n) reactions on low Z nuclides. Measurements of (/alpha/,n) thick target neutron yields and associated neutron spectra have been made for only a few combinations of /alpha/ energy and target nuclide or mixtures of actinide and target nuclides. Calculations of thick target neutron yields and spectra with the SOURCES code require /alpha/-energy-dependent cross sections for (/alpha/,n) reactions, as well as branching fractions leading to the energetically possible levels of the product nuclides. A library of these data has been accumulated for target nuclides of Z /le/ 15 using that available from measurements and from recent GNASH code calculations. SOURCES, assuming neutrons to be emitted isotopically in the center-of-mass system, uses libraries of /alpha/ stopping cross sections, (/alpha/,n) reaction cross reactions, product nuclide level branching fractions, and actinide decay /alpha/ spectra to calculate thick target (/alpha/,n) yields and neutron spectra for homogeneous combinations of nuclides. The code also calculates the thick target yield and angle intergrated neutron spectrum produced by /alpha/-particle beams on targets of homogeneous mixtures of nuclides. Illustrative calculated results are given and comparisons are made with measured thick target yields and spectra. 50 refs., 1 fig., 2 tabs.

  14. Spallation neutron spectra measurements Part I: Time-of-flight technique

    NASA Astrophysics Data System (ADS)

    Borne, F.; Crespin, S.; Leray, S.; Patin, Y.; Beau, M.; Boudard, A.; Boué, F.; Bouyer, P.; Boyard, J. L.; Brochard, F.; Drake, D.; Duchazeaubeneix, J. C.; Durand, J. M.; Fréhaut, J.; Kowalski, L.; Legrain, R.; Lochard, J. P.; Martinez, E.; Ménard, S.; Milleret, G.; Petibon, E.; Plouin, F.; Terrien, Y.; Thun, J.; Uematsu, M.; Vuillier, S.; Whittal, D. M.

    1997-01-01

    We present an experimental method based on a time-of-flight technique between the tagged incident particles and a thick liquid NE213 scintillator to measure neutron energy spectra from 3 to 400 MeV at the Saturne synchrotron of Saclay. Efficiency measurements are made using a pulsed neutron source from the Tandem Van de Graaff of Bruyères-le-Châtel at low energies and a quasi-monoenergetic neutron beam at Saturne up to 50 MeV.

  15. Analysis of primary damage in silicon carbide under fusion and fission neutron spectra

    NASA Astrophysics Data System (ADS)

    Guo, Daxi; Zang, Hang; Zhang, Peng; Xi, Jianqi; Li, Tao; Ma, Li; He, Chaohui

    2014-12-01

    Irradiation parameters on primary damage states of SiC are evaluated and compared for the first wall of ITER under deuterium-deuterium (DD) and deuterium-tritium (DT) operation, the high temperature gas-cooled reactor (HTGR) and high flux isotope reactor (HFIR). With the same neutron fluence, the studied fusion spectra produce more damage and much higher gas production than the fission spectra. Due to comparable gas production and similar weighted primary recoil spectra, HFIR is considered suitable to simulate the neutron irradiation in an HTGR. In contrast to the significant differences between the weighted primary recoil spectra of the fission and the fusion spectra, the weighted secondary recoil spectra of HFIR and HTGR match those of DD and DT, indicating that displacement cascades by the fission and the fusion irradiation are similar when the damage distribution among damaged regions by secondary recoils is taken into account.

  16. Irradiation tests of ITER candidate Hall sensors using two types of neutron spectra

    SciTech Connect

    Duran, I. [Institute of Plasma Physics AS CR, v. v. i., Association EURATOM/IPP.CR, 182 00 Prague 8 (Czech Republic); Bolshakova, I.; Holyaka, R. [Magnetic Sensor Laboratory, Lviv Polytechnic National University, 790 31 Lviv (Ukraine); Viererbl, L.; Lahodova, Z. [Nuclear Research Institute plc., 250 68 Husinec-Rez (Czech Republic); Sentkerestiova, J. [Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, 115 19 Prague 1 (Czech Republic); Bem, P. [Nuclear Physics Institute AS CR, v. v. i., 250 68 Husinec-Rez (Czech Republic)

    2010-10-15

    We report on irradiation tests of InSb based Hall sensors at two irradiation facilities with two distinct types of neutron spectra. One was a fission reactor neutron spectrum with a significant presence of thermal neutrons, while another one was purely fast neutron field. Total neutron fluence of the order of 10{sup 16} cm{sup -2} was accumulated in both cases, leading to significant drop of Hall sensor sensitivity in case of fission reactor spectrum, while stable performance was observed at purely fast neutron spectrum. This finding suggests that performance of this particular type of Hall sensors is governed dominantly by transmutation. Additionally, it further stresses the need to test ITER candidate Hall sensors under neutron flux with ITER relevant spectrum.

  17. Irradiation tests of ITER candidate Hall sensors using two types of neutron spectra

    NASA Astrophysics Data System (ADS)

    ?uran, I.; Bolshakova, I.; Viererbl, L.; Sentkerestiová, J.; Holyaka, R.; Lahodová, Z.; Bém, P.

    2010-10-01

    We report on irradiation tests of InSb based Hall sensors at two irradiation facilities with two distinct types of neutron spectra. One was a fission reactor neutron spectrum with a significant presence of thermal neutrons, while another one was purely fast neutron field. Total neutron fluence of the order of 1016 cm-2 was accumulated in both cases, leading to significant drop of Hall sensor sensitivity in case of fission reactor spectrum, while stable performance was observed at purely fast neutron spectrum. This finding suggests that performance of this particular type of Hall sensors is governed dominantly by transmutation. Additionally, it further stresses the need to test ITER candidate Hall sensors under neutron flux with ITER relevant spectrum.

  18. Calculations of neutron flux spectra induced in the earth's atmosphere by galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Chandler, K. C.; Barish, J.

    1972-01-01

    Calculations have been carried out to determine the neutron flux induced in the earth's atmosphere by galactic protons and alpha particles at solar minimum for a geomagnetic latitude of 42 N. Neutron flux spectra were calculated using Monte Carlo and discrete ordinates methods, and various comparisons with experimental data are presented. The magnitude and shape of the calculated neutron-leakage spectrum at the particular latitude considered support the theory that the cosmic-ray-albedo-neutron-decay mechanism is the source of the protons and electrons trapped in the Van Allen belts.

  19. Neutron activation analysis at Texas Instruments

    Microsoft Academic Search

    J. Keenan; T. Hossain; B. Gnade

    1990-01-01

    Instrumental neutron activation analysis provides the high sensitivity required for detection of dopants and adventitious impurities in polycrystalline silicon, pulled crystals, and processed wafers. Reactor produced isotopes such as ¹Au provide sufficient sensitivity to study gettering mechanisms at levels equivalent to those of adventitious impurities in processed silicon. Detection of neutron-induced alpha particle radiation provides a quantitative basis for determining

  20. Broad-range neutron spectra identification in ultraintense laser interactions with carbon-deuterated plasma

    SciTech Connect

    Youssef, A.; Kodama, R.; Habara, H.; Tanaka, K.A.; Sentoku, Y.; Tampo, M.; Toyama, Y. [Graduate School of Engineering, Osaka University, 2-1 Suita, Osaka 565-0871 (Japan); Graduate School of Engineering, Osaka University, 2-1 Suita, Osaka 565-0871, Japan and Institute of Laser Engineering, Osaka University, 2-6 Suita, Osaka 565-0871 (Japan); Department of Physics, University of Nevada, MS-220, Reno, Nevada 89557 (United States); Institute of Laser Engineering, Osaka University, 2-6 Suita, Osaka 565-0871 (Japan)

    2005-11-15

    Detailed neutron energy spectra produced from a CD2 target irradiated by a 450 fs, 20 J, 1053 nm laser at an intensity of 3x10{sup 18} W/cm{sup 2} have been studied. Wide-ranging neutron spectra were observed from two different observation angles 20 deg. and 70 deg. relative to the rear-side target normal. The experiment and numerically calculated spectra, by a three-dimensional Monte Carlo code, indicate that the range of the measured spectra is larger than that produced by the D(d,n){sup 3}He reaction. An interpretation for the measured spectra is introduced by considering the {sup 12}C(d,n){sup 13}N and D({sup 12}c,n){sup 13}N reactions. In addition, the study revealed that the neutron spectra produced by the D-C and C-D reactions can overlap that produced by the D-D reaction, and due to their high cross sections, comparing to the D-D reaction, both of them effectively participate in the neutron yield.

  1. NONDESTRUCTIVE MULTIELEMENT INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS

    EPA Science Inventory

    A nondestructive instrumental neutron activation analysis procedure permitted accurate and sensitive measurement of most elements with atomic numbers between 11 and 92. The sensitivity of the procedure was dependent on each element's intrinsic characteristics and the sample matri...

  2. Composite delayed neutron energy spectra for thermal fission of /sup 235/U

    SciTech Connect

    Tanczyn, R.S.; Sharfuddin, Q.; Schier, W.A.; Pullen, D.J.; Haghighi, M.H.; Fisteag, L.; Couchell, G.P.

    1986-12-01

    Composite delayed neutron energy spectra from the thermal neutron fission of /sup 235/U have been measured for eight delay-time intervals between 0.17 and 85.5 s. This experimental technique combines a helium-jet and tape transfer system with a beta-neutron time-of-flight spectrometer. The neutron energy range of 0.01 to 2.0 MeV is spanned with /sup 6/Li-glass, plastic, and liquid scintillators. Spectra are compared to ENDF/B-V as well as to individual precursors' data and average energies are tabulated for the present and previous compilations. An equilibrium spectrum is also calculated and compared to ENDF/B-V and individual precursor measurements.

  3. Activities on Nuclear Data Measurements at Pohang Neutron Facility

    SciTech Connect

    Kim, Guinyun [Department of Physics, Kyungpook National University, 1370 Sankyuk-Dong, Buk-Gu, Daegu 702-701 (Korea, Republic of)

    2009-03-31

    We report the activities of the Pohang Neutron Facility which consists of an electron linear accelerator, a water-cooled Ta target, and a 12-m time-of-flight path. It has been equipped with a four-position sample changer controlled remotely by a CAMAC data acquisition system, which allows simultaneous accumulation of the neutron time of flight spectra from 4 different detectors. It can be possible to measure the neutron total cross-sections in the neutron energy range from 0.1 eV to few hundreds eV by using the neutron time-of-flight method. A {sup 6}LiZnS(Ag) glass scintillator was used as a neutron detector. The neutron flight path from the water-cooled Ta target to the neutron detector was 12.1 m. The background level was determined by using notch-filters of Co, In, Ta, and Cd sheets. In order to reduce the gamma rays from bremsstrahlung and those from neutron capture, we employed a neutron-gamma separation system based on their different pulse shapes. The present measurements of several samples (Ta, Mo) are in general agreement with the evaluated data in ENDF/B-VI. We measured the thermal neutron capture cross-sections and the resonance integrals of the {sup 186}W(n,{gamma}){sup 187}W reaction and the {sup 98}Mo(n,{gamma}){sup 99}Mo reaction by the activation method using the {sup 197}Au(n,{gamma}){sup 198}Au monitor reaction as a single comparator. We also report the isomeric yield ratios for the 44 m, gSc isomeric pairs produced from four different photonuclear reactions {sup 45}Sc({gamma},n){sup 44m,g}Sc, {sup nat}Ti({gamma},xn1p){sup 44m,g}Sc, {sup nat}Fe({gamma},xn5p){sup 52m,g}Mn, and {sup 103}Rh({gamma},4n){sup 99m,g}Rh by using the activation method.

  4. A fast and flexible reactor physics model for simulating neutron spectra and depletion in fast reactors

    NASA Astrophysics Data System (ADS)

    Recktenwald, Geoff; Deinert, Mark

    2010-03-01

    Determining the time dependent concentration of isotopes within a nuclear reactor core is central to the analysis of nuclear fuel cycles. We present a fast, flexible tool for determining the time dependent neutron spectrum within fast reactors. The code (VBUDS: visualization, burnup, depletion and spectra) uses a two region, multigroup collision probability model to simulate the energy dependent neutron flux and tracks the buildup and burnout of 24 actinides, as well as fission products. While originally developed for LWR simulations, the model is shown to produce fast reactor spectra that show high degree of fidelity to available fast reactor benchmarks.

  5. Neutron counter based on beryllium activation

    SciTech Connect

    Bienkowska, B.; Prokopowicz, R.; Kaczmarczyk, J.; Paducha, M. [Institute of Plasma Physics and Laser Microfusion (IPPLM), Hery 23, 01-497 Warsaw (Poland); Scholz, M.; Igielski, A. [Institute of Nuclear Physics PAS (IFJPAN), Radzikowskiego 152, 31-342 Krakow (Poland); Karpinski, L. [Faculty of Electrical Engineering, Rzeszow University of Technology, Pola 2, 35-959 Rzeszow (Poland); Pytel, K. [National Centre for Nuclear Research (NCBJ), Soltana 7, 05-400 Otwock - Swierk (Poland)

    2014-08-21

    The fusion reaction occurring in DD plasma is followed by emission of 2.45 MeV neutrons, which carry out information about fusion reaction rate and plasma parameters and properties as well. Neutron activation of beryllium has been chosen for detection of DD fusion neutrons. The cross-section for reaction {sup 9}Be(n, ?){sup 6}He has a useful threshold near 1 MeV, which means that undesirable multiple-scattered neutrons do not undergo that reaction and therefore are not recorded. The product of the reaction, {sup 6}He, decays with half-life T{sub 1/2} = 0.807 s emitting ?{sup ?} particles which are easy to detect. Large area gas sealed proportional detector has been chosen as a counter of ?–particles leaving activated beryllium plate. The plate with optimized dimensions adjoins the proportional counter entrance window. Such set-up is also equipped with appropriate electronic components and forms beryllium neutron activation counter. The neutron flux density on beryllium plate can be determined from the number of counts. The proper calibration procedure needs to be performed, therefore, to establish such relation. The measurements with the use of known ?–source have been done. In order to determine the detector response function such experiment have been modeled by means of MCNP5–the Monte Carlo transport code. It allowed proper application of the results of transport calculations of ?{sup ?} particles emitted from radioactive {sup 6}He and reaching proportional detector active volume. In order to test the counter system and measuring procedure a number of experiments have been performed on PF devices. The experimental conditions have been simulated by means of MCNP5. The correctness of simulation outcome have been proved by measurements with known radioactive neutron source. The results of the DD fusion neutron measurements have been compared with other neutron diagnostics.

  6. X-Ray Spectra of Bursting Neutron Stars and Color Temperature - Luminosity Diagram

    Microsoft Academic Search

    T. Ebisuzaki; K. Nomoto

    1985-01-01

    The authors calculate atmospheric models and emitted X-ray spectra for X-ray bursting neutron stars taking into account the effects of Comptonization and free-free and bound-free emission and absorption. The color temperatures obtained from the calculated X-ray spectra are higher than the effective temperatures. The theoretical color-temperature to luminosity diagram is in good agreement with the observational diagram of MXB 1636-536

  7. Analytic expression for epithermal neutron spectra amplitudes as a function of water content

    NASA Technical Reports Server (NTRS)

    Drake, Darrell

    1993-01-01

    The epithermal portion of an equilibrium neutron spectrum in a planetary body is a function of the water content of its material. The neutrons are produced at high energies but are moderated by elastic and inelastic scattering until they either are captured by surrounding nuclei or escape. We have derived an expression that explicitly shows the dependance of epithermal neutron spectra on water content. Additionally, we compared its predictions to calculations done by Boltzman transport code for infinite media for silicon, oxygen, and a possible lunar composition, and we have obtained very good agreement.

  8. Neutron coincidence imaging for active and passive neutron assays

    SciTech Connect

    Estep, R. J. (Robert J.); Brunson, G. S. (Glenn S.); Melton, S. G. (Sheila G.)

    2001-01-01

    Neutron multiplicity assay algorithms for {sup 240}Pu assume a point source of fission neutrons that are detected in a single detector channel. The {sup 240}Pu in real waste, however, is more likely to be distributed throughout the container in some random way. For different reasons, this leads to significant errors when using either multiplicity or simpler coincidence analyses. Reduction of these errors can be achieved using tomographic imaging. In this talk we report on our results from using neutron singles and coincidence data between tagged detector pairs to provide enhanced tomographic imaging capabilities to a crate nondestructive assay system. Only simulated passive coincidence data is examined here, although the higher signal rates from active coincidence counting hold more promise for waste management. The active coincidence approach has significantly better sensitivity than the passive and is not significantly perturbed by (alpha,n) contributions. Our study was based primarily on simulated neutron pulse trains derived from the Los Alamos SIM3D software, which were subjected to analysis using the Los Alamos CTEN-FIT and TGS-FIT software. We found significantly improved imaging capability using the coincidence and singles rate data than could be obtained using the singles rate alone.

  9. Neutron capture cross section and capture gamma-ray spectra of 138Ba in the keV-neutron energy region

    NASA Astrophysics Data System (ADS)

    Katabuchi, T.; Yanagida, S.; Terada, K.; Iwamoto, N.; Igashira, M.

    2015-05-01

    The neutron capture cross sections and the capture ?-ray spectra of 138Ba were measured in the astrophysically important energy region. Measurements were made at neutron energies from 15 to 80 keV. The neutron energy was determined by the time-of-flight method. The ?-ray spectra showed that the primary transition pattern strongly depended on the incident neutron energy. The neutron capture cross sections were derived by the pulse height weighting technique. The present cross section values were compared with evaluated cross section data and previous measurements.

  10. Extrapolated neutron activation cross sections for dosimetry to 44 MeV

    Microsoft Academic Search

    1978-01-01

    Thirty-one neutron activation cross sections have been extrapolated to 44 MeV for dosimetry applications at high-energy, accelerator-based neutron sources. All cross sections have undergone integral testing in Be(d,n) fields at E\\/sub d\\/ = 14, 16, and 40 MeV. The integral activities for most of the reactions agree within 10% with calculations based on time-of-flight measurements of the flux spectra. Tests

  11. Theoretical description of prompt fission neutron multiplicity and spectra

    E-print Network

    Cristian Manailescu

    2014-10-16

    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 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 IV. The last chapter includes an overview of the most important conclusions resulting from the intercomparison of the results obtained with both treatments in chapter IV.

  12. NEUTRON ACTIVATION CROSS SECTIONS AT 25 Kev

    Microsoft Academic Search

    Rex Booth; William Ball; Malcolm MacGregor

    1958-01-01

    Neutron activation cross sections have been measured at 25 kev for 31 ; isotopes. An Sb-Be photoneutron source was used, and thermal activations served ; to calibrate the beta- and gamma-detector efficiencies. The cross sections were ; measnred relative to iodine. A comparison was made between measured cross ; sections and predictions based on known low-energy resonance parameters. (auth);

  13. Neutron Activation Cross Sections at 25 kev

    Microsoft Academic Search

    Rex Booth; William P. Ball; Malcolm H. MacGregor

    1958-01-01

    Neutron activation cross sections have been measured at 25 kev for 31 isotopes. An Sb-Be photoneutron source was used, and thermal activations served to calibrate the beta- and gamma-detector efficiencies. The cross sections were measured relative to iodine. A comparison was made between measured cross sections and predictions based on known low-energy resonance parameters.

  14. Neutron Activation Cross Sections with Sb-Be Neutrons

    Microsoft Academic Search

    R. L. Macklin; N. H. Lazar; W. S. Lyon

    1957-01-01

    The neutron activation cross sections near 25 kev have been measured for about 50 nuclei. Gamma-ray scintillation spectrometers with known efficiency were used to compare the radioactivities produced by the several nuclei with I128. This gave a significant increase in sensitivity and precision over direct beta-counting methods in many cases. Absolute standardization was obtained through scintillation-beta-counting the I128 in NaI(Tl)

  15. Calculation of delayed-neutron energy spectra in a quasiparticle random-phase approximation-Hauser-Feshbach model

    SciTech Connect

    Kawano, T.; Moeller, P.; Wilson, W. B. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2008-11-15

    Theoretical {beta}-delayed-neutron spectra are calculated based on the Quasiparticle Random-Phase Approximation (QRPA) and the Hauser-Feshbach statistical model. Neutron emissions from an excited daughter nucleus after {beta} decay to the granddaughter residual are more accurately calculated than in previous evaluations, including all the microscopic nuclear structure information, such as a Gamow-Teller strength distribution and discrete states in the granddaughter. The calculated delayed-neutron spectra agree reasonably well with those evaluations in the ENDF decay library, which are based on experimental data. The model was adopted to generate the delayed-neutron spectra for all 271 precursors.

  16. Basic concept and characteristics of beam quality indicator for continuum neutron spectra

    Microsoft Academic Search

    Hisao Kobayashi; Yoshiaki Kiyanagi

    1996-01-01

    Characteristics of a beam quality indicator (BQI), which has been recently developed to determine an effective energy of neutron beams with continuum spectra, are studied by means of a simplified calculation. The effective energy is defined with respect to a thickness ratio corresponding to the ratio of two energy dependent cross sections. The thickness ratio is defined such that the

  17. Dynamics of Myoglobin: Comparison of Simulation Results with Neutron Scattering Spectra

    Microsoft Academic Search

    Jeremy Smith; Krzysztof Kuczera; Martin Karplus

    1990-01-01

    Molecular dynamics simulations are used to calculate the incoherent neutron scattering spectra of myoglobin between 80 K and 325 K and compared with experimental data. There is good agreement over the entire temperature range for the elastic, quasi-elastic, and inelastic components of the scattering. This provides support for the accuracy of the simulations of the internal motions that make the

  18. Measurement of inclusive zero-angle neutron spectra at the CERN ISR

    Microsoft Academic Search

    W. Flauger; F. Mönnig

    1976-01-01

    With a total absorption spectrometer, inclusive neutron spectra have been measured at four ISR energies at zero degrees. The invariant cross sections show scaling behaviour in x with an important contribution of pion exchange at large x. At &surd;s = 52.8 GeV the spectrum of photons is given for x <= 0.375.

  19. Prompt fission neutron spectra and anti. nu. p

    SciTech Connect

    Madland, D.G.

    1980-09-22

    Methods used to obtain the evaluated prompt fisson neutron spectrum N(E) and the average prompt neutron multiplicity anti ..nu../sub p/ are reviewed. The relative influence of experimental data; interpolated, extrapolated, and fitted experimental data; systematics; and nuclear theory are considered for the cases where (a) abundant experimental data exist, (b) some experimental data exist, and (c) no experimental data exist. The Maxwellian and Watt distributions, and the determination of the parameters of these distributions by data fitting, are described and compared to recent new theoretical work on the calculation of N(E). Similarly, various expressions for anti ..gamma../sub p/ that have been obtained by data fitting and systematics are described and compared to recent new theoretical work. Complications in the evaluation of N(E) and anti ..gamma../sub p/ due to the onset of multiple-chance fission and the interrelationships between N(E), anti ..gamma delta../sub p/ and the multiple-chance fission cross section are discussed using the example of the fission of /sup 235/U. Some statistics and comments are given on the evaluations of N(E) and anti ..gamma../sub p/ contained in ENDF/B-V, and a number of concluding recommendations are made for future evaluation work.

  20. The effects of boron on the electron paramagnetic resonance spectra of alanine irradiated with thermal neutrons

    SciTech Connect

    Ciesielski, B.; Wielopolski, L. [Brookhaven National Lab., Upton, NY (United States)

    1995-10-01

    The effects of boric acid admixture on the intensity and line structure of EPR spectra of free radicals produced in alanine by thermal neutrons are presented. The EPR signal enhancement, up to a factor of 40 depending on the boron concentration, is related to additional energy deposition in alanine crystals by the disintegration products resulting from the capture of a thermal neutron by boron, {sup 10}B(n,{alpha}){sup 7}Li. The changes in the shape of the EPR spectra observed by changing the microwave power are due to the differences in the microwave power saturation of the free radicals produced by a low-LET radiation and those produced by the high-LET components of the radiation after the neutron capture reaction. 27 refs., 4 figs., 2 tabs.

  1. Gravitational light bending near neutron stars. II. Accreting pulsar spectra as a function of phase

    SciTech Connect

    Meszaros, P.; Riffert, H.

    1988-04-01

    This paper presents X-ray pulse shapes and phase-dependent cyclotron spectra of simple accretion column and accretion cap models of rotating magnetized neutron stars, including general relativistic light-bending effects. It is shown that the latter effects can be strong, and the beaming properties and phase-dependent spectral properties are discussed as a function of the stellar radius, using realistic magnetized input spectra. It is also shown that a qualitatively correct fit to the observations of Her X-1 can be obtained only in two situations: either the accretion is of the cap type and the neutron star radius is larger than about four Schwarzschild radii, or else the accretion is of the column type and the neutron star radius is of the order of 1.6 Schwarzschild radii. On the basis of various theoretical arguments and the current status of other evidence, the latter seems indicated at present. 26 references.

  2. Temperature Profiles and Spectra of Accretion Disks around Rapidly Rotating Neutron Stars

    E-print Network

    Sudip Bhattacharyya

    2002-05-09

    We calculate temperature profiles and X-ray spectra of accretion disks around rapidly rotating neutron stars considering the full effect of general relativity. Computed disk temperatures and luminosities are compared with the EXOSAT data to constrain the properties of five low-mass-X-ray-binary sources. We fit our model-spectra with an analytical function, which can in turn be used for routine spectral fitting work. Our equation-of-state dependent spectral model may be useful to constrain the equation-of-state models of neutron stars. We also compare the properties of a rotating neutron star with those of a rotating strange star with the hope of giving a possible way to identify a strange star, which will be important for the verification of strange-quark-matter hypothesis.

  3. Neutron spectrum measurements using proton recoil proportional counters: results of measurements of leakage spectra for the Little Boy assembly

    SciTech Connect

    Bennett, E.F.; Yule, T.J.

    1984-01-01

    Measurements of degraded fission-neutron spectra using recoil proportional counters are done routinely for studies involving fast reactor mockups. The same techniques are applicable to measurements of neutron spectra required for personnel dosimetry in fast neutron environments. A brief discussion of current applications of these methods together with the results of a measurement made on the LITTLE BOY assembly at Los Alamos are here described.

  4. Relative measurements of the mean number of neutrons emitted in fission of U 233 , U 235 and Pu 239 by thermal neutrons and by neutrons characteristic of a fission spectra

    Microsoft Academic Search

    V. I. Kalashnikova; V. I. Lebedev; P. E. Spivak

    1957-01-01

    The ratios of the mean number of neutrons (?) emitted in the fission of U233, U235 and Pu239 by thermal neutrons and by neutrons characteristic of a fission spectra have been measured. A method was employed in which the number of fission events was counted simultaneously with the number of coincidences between fragments and fission neutrons. It is found that

  5. Vibrational spectra of light and heavy water with application to neutron cross section calculations.

    PubMed

    Marquez Damian, J I; Malaspina, D C; Granada, J R

    2013-07-14

    The design of nuclear reactors and neutron moderators require a good representation of the interaction of low energy (E < 1 eV) neutrons with hydrogen and deuterium containing materials. These models are based on the dynamics of the material, represented by its vibrational spectrum. In this paper, we show calculations of the frequency spectrum for light and heavy water at room temperature using two flexible point charge potentials: SPC-MPG and TIP4P/2005f. The results are compared with experimental measurements, with emphasis on inelastic neutron scattering data. Finally, the resulting spectra are applied to calculation of neutron scattering cross sections for these materials, which were found to be a significant improvement over library data. PMID:23862950

  6. Calculations of neutron flux spectra induced in the earth's atmosphere by galactic cosmic rays.

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Chandler, K. C.; Barish, J.

    1973-01-01

    Calculations have been carried out to determine the neutron flux induced in the earth's atmosphere by galactic protons and alpha particles at solar minimum for a geomagnetic latitude of 42 N. Neutron flux spectra in the energy range from about 10 to the minus 8th to about 100,000 MeV at various depths in the atmosphere were calculated by using Monte Carlo and discrete ordinates methods, and various comparisons with experimental data are presented. The magnitude and shape of the calculated neutron leakage spectrum at the particular latitude considered support the theory that the cosmic ray albedo neutron decay (Crand) mechanism is the source of the protons trapped in the inner radiation belt.

  7. An integral test of the inelastic cross sections of Pb and Mo using measured neutron spectra

    NASA Technical Reports Server (NTRS)

    Shook, D. F.; Fieno, D.; Ford, C. H.; Wrights, G. N.

    1972-01-01

    Comparison of measurements and calculations of fast neutron spectra from a radioactive neutron source inside spheres of Mo or Pb and from a cylindrical reactor containing a thick Pb or Mo reflector are used as a test of ENDF cross sections. The sphere leakage spectra were measured at a sphere-to-spectrometer distance of 2 meters using a 54 Ci spherical Am-Be neutron source. Reactor leakage spectrum measurements were made at the surface of the ZP-1 reactor when bare, with a Pb radial reflector 21 cm thick, and with a metallic Mo radial reflector 10 cm thick. In the case of the thin Mo sphere there is agreement between the calculation and measurement. The Pb calculation is much lower than the measurement except at the highest neutron energy. Two-dimensional calculations of reactor spectra result indicate that the reactor source is reasonably well known. Significant differences in leakage spectrum shape for both Mo and Pb reflectors suggest that there are large uncertainties in the inelastic cross sections for Pb and some for Mo.

  8. Instrumental Neutron Activation Analysis of Extractable

    Microsoft Academic Search

    M. Kawano; J. Falandysz; T. Wakimoto

    2003-01-01

    Instrumental neutron activation analysis was performed to measure the levels of extractable organohalogens (EOX) in the organisms from the Antarctic marine ecosystem. The results show that EOX (EOCl, EOBr and EOI) were found in all the samples analyzed. The highest concentration was determined in the ascidian sample. The concentration order of EOX was mainly EOCl>EOBr>EOI with the exception of nemertine,

  9. Neutron activation cross sections on lead isotopes

    Microsoft Academic Search

    V. Semkova; P. Reimer; T. Altzitzoglou; A. J. M. Plompen; C. Quetel; S. Sudar; J. Vogl; A. J. Koning; S. M. Qaim; D. L. Smith

    2009-01-01

    The cross sections for the reactions ²°Pb(n,n{sup '})²°Pb{sup m}, ²°Pb(n,2n)²°³Pb, ²°Pb(n,2n)²°³Pb{sup m1}, ²°Pb(n,3n)²°²Pb{sup m}, ²°Pb(n,3n)²°Pb{sup m}, ²°Pb(n,)²°³Hg, and ²°Pb(n,p)²°Tl were determined at the IRMM van de Graaff laboratory in the neutron energy range from 14 to 21 MeV. Both natural and enriched samples were irradiated with neutrons produced via the ³H(d,n)He reaction. The induced activities were determined by gamma-ray spectrometry

  10. Measurement of U-235 Fission Neutron Spectra Using a Multiple Gamma Coincidence Technique

    SciTech Connect

    Ji Chuncheng; Kegel, G.H.R.; Egan, J.J.; DeSimone, D.J.; Alimeti, A.; Roldan, C.F.; McKittrick, T.M.; Kim, D.-S.; Chen, X.; Tremblay, S.E. [Department of Physics and Applied Physics, University of Massachusetts Lowell, One University Avenue, Lowell, MA 01854 (United States)

    2005-05-24

    The Los Alamos Model of Madland and Nix predicts the shape of the fission neutron energy spectrum for incident primary neutrons of different energies. Verifications of the model normally are limited to measurements of the fission neutron spectra for energies higher than that of the primary neutrons because the low-energy spectrum is distorted by the admixture of elastically and inelastically scattered neutrons. This situation can be remedied by using a measuring technique that separates fission from scattering events. One solution consists of using a fissile sample so thin that fission fragments can be observed indicating the occurrence of a fission event. A different approach is considered in this paper. It has been established that a fission event is accompanied by the emission of between seven and eight gamma rays, while in a scattering interaction, between zero and two gammas are emitted, so that a gamma multiplicity detector should supply a datum to distinguish a fission event from a scattering event. We proceed as follows: A subnanosecond pulsed and bunched proton beam from the UML Van de Graaff generates nearly mono-energetic neutrons by irradiating a thin metallic lithium target. The neutrons irradiate a 235U sample. Emerging neutron energies are measured with a time-of-flight spectrometer. A set of four BaF2 detectors is located close to the 235U sample. These detectors together with their electronic components identify five different events for each neutron detected, i.e., whether four, three, two, one, or none of the BaF2 detectors received one (or more) gamma rays. We present work, preliminary to the final measurements, involving feasibility considerations based on gamma-ray coincidence measurements with four BaF2 detectors, and the design of a Fission-Scattering Discriminator under construction.

  11. Instrumental neutron activation analysis of Obsidian rock

    Microsoft Academic Search

    S. Ahmad; M. S. Chaudhary; I. H. Qureshi

    1981-01-01

    An instrumental neutron activation analysis technique has been developed for the simultaneous determination of up to 30 elements\\u000a including major, minor and trace elements in Obsidian Rock (a proposed NBS-SRM-278). INAA method involves both short and long\\u000a irradiations followed by gamma-ray activity measurement with a Ge(Li) detector. The accuracy of the procedure has been checked\\u000a by analyzing IAEA Reference Materials.

  12. Phantom studies of Cd, Hg and Cl by prompt gamma neutron activation analysis using a 238Pu Be neutron source

    NASA Astrophysics Data System (ADS)

    Grinyer, J.; Atanackovic, J.; Byun, S. H.; Chettle, D. R.

    2007-10-01

    Prompt gamma neutron activation analysis is a means of non-invasive monitoring for occupational exposure to toxic heavy metals such as Cd and Hg. Preliminary kidney detection limits from previous phantom studies at McMaster were 13.6 ± 0.2 ppm for Cd (125 mL phantom) and 315 ± 24 ppm for Hg (125 mL phantom) using the 238Pu-Be neutron source and 0.88 ± 0.01 ppm for Cd (125 mL phantom) and 16.91 ± 0.05 ppm for Hg (30 mL phantom) using the thermal neutron beam port at the McMaster Nuclear Reactor. The detection limits vary greatly between the two methods due to differences in experimental set-up, neutron energy spectra and a difference in dose by more than a factor of 100. The Hg detection limit from preliminary data is much higher than expected for both neutron source types. In order to explain the apparent detection limit discrepancy, measurements of Hg and Cd phantoms were performed using the 238Pu-Be neutron source. The results were compared to phantom measurements of Cl, a well-known neutron activation element.

  13. Neutron spectra and dose equivalents calculated in tissue for high-energy radiation therapy

    PubMed Central

    Kry, Stephen F.; Howell, Rebecca M.; Salehpour, Mohammad; Followill, David S.

    2009-01-01

    Neutrons are by-products of high-energy radiation therapy and a source of dose to normal tissues. Thus, the presence of neutrons increases a patient’s risk of radiation-induced secondary cancer. Although neutrons have been thoroughly studied in air, little research has been focused on neutrons at depths in the patient where radiosensitive structures may exist, resulting in wide variations in neutron dose equivalents between studies. In this study, we characterized properties of neutrons produced during high-energy radiation therapy as a function of their depth in tissue and for different field sizes and different source-to-surface distances (SSD). We used a previously developed Monte Carlo model of an accelerator operated at 18 MV to calculate the neutron fluences, energy spectra, quality factors, and dose equivalents in air and in tissue at depths ranging from 0.1 to 25 cm. In conjunction with the sharply decreasing dose equivalent with increased depth in tissue, the authors found that the neutron energy spectrum changed drastically as a function of depth in tissue. The neutron fluence decreased gradually as the depth increased, while the average neutron energy decreased sharply with increasing depth until a depth of approximately 7.5 cm in tissue, after which it remained nearly constant. There was minimal variation in the quality factor as a function of depth. At a given depth in tissue, the neutron dose equivalent increased slightly with increasing field size and decreasing SSD; however, the percentage depth-dose equivalent curve remained constant outside the primary photon field. Because the neutron dose equivalent, fluence, and energy spectrum changed substantially with depth in tissue, we concluded that when the neutron dose equivalent is being determined at a depth within a patient, the spectrum and quality factor used should be appropriate for depth rather than for in-air conditions. Alternately, an appropriate percent depth-dose equivalent curve should be used to correct the dose equivalent at the patient surface. PMID:19472632

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

    SciTech Connect

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

    2012-10-23

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

  15. Neutron Yield Measurements via Aluminum Activation

    SciTech Connect

    None

    1999-12-08

    Neutron activation of aluminum may occur by several neutron capture reactions. Four such reactions are described here: {sup 27}Al + n = {sup 28}Al, {sup 27}Al(n,{alpha}){sup 24}Na, {sup 27}Al(n, 2n){sup 26}Al and {sup 27}Al(n,p){sup 27}Mg. The radioactive nuclei {sup 28}Al, {sup 24}Na, and {sup 27}Mg, which are produced via the {sup 27}Al + n = {sup 28}Al, {sup 27}Al(n,{alpha}){sup 24}Na and {sup 27}Al(n,p){sup 27}Mg neutron reactions, beta decay to excited states of {sup 28}Si, {sup 24}Mg and {sup 27}Al respectively. These excited states then emit gamma rays as the nuclei de-excite to their respective ground states.

  16. High-resolution spectroscopy used to measure inertial confinement fusion neutron spectra on Omega (invited)

    SciTech Connect

    Forrest, C. J.; Radha, P. B.; Glebov, V. Yu.; Goncharov, V. N.; Knauer, J. P.; Pruyne, A.; Romanofsky, M.; Sangster, T. C.; Shoup, M. J. III; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 (United States); Casey, D. T.; Gatu-Johnson, M. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 (United States); Gardner, S. [Constellation Energy Nuclear Group, Ontario, New York 14519 (United States)

    2012-10-15

    The areal density ({rho}R) of cryogenic DT implosions on Omega is inferred by measuring the spectrum of neutrons that elastically scatter off the dense deuterium (D) and tritium (T) fuel. Neutron time-of-flight (nTOF) techniques are used to measure the energy spectrum with high resolution. High signal-to-background data has been recorded on cryogenic DT implosions using a well-collimated 13.4-m line of sight and an nTOF detector with an advanced liquid scintillator compound. An innovative method to analyze the elastically scattered neutron spectra was developed using well-known cross sections of the DT nuclear reactions. The estimated areal densities are consistent with alternative {rho}R measurements and 1-D simulations.

  17. Analysis of accelerator based neutron spectra for BNCT using proton recoil spectroscopy

    SciTech Connect

    Wielopolski, L.; Ludewig, H.; Powell, J.R.; Raparia, D.; Alessi, J.G.; Lowenstein, D.I.

    1999-03-01

    Boron Neutron Capture Therapy (BNCT) is a promising binary treatment modality for high-grade primary brain tumors (glioblastoma multiforme, GM) and other cancers. BNCT employs a boron-10 containing compound that preferentially accumulates in the cancer cells in the brain. Upon neutron capture by {sup 10}B energetic alpha particles and triton released at the absorption site kill the cancer cell. In order to gain penetration depth in the brain Fairchild proposed, for this purpose, the use of energetic epithermal neutrons at about 10 keV. Phase 1/2 clinical trials of BNCT for GM are underway at the Brookhaven Medical Research Reactor (BMRR) and at the MIT Reactor, using these nuclear reactors as the source for epithermal neutrons. In light of the limitations of new reactor installations, e.g. cost, safety and licensing, and limited capability for modulating the reactor based neutron beam energy spectra, alternative neutron sources are being contemplated for wider implementation of this modality in a hospital environment. For example, accelerator based neutron sources offer the possibility of tailoring the neutron beams, in terms of improved depth-dose distributions, to the individual and offer, with relative ease, the capability of modifying the neutron beam energy and port size. In previous work new concepts for compact accelerator/target configuration were published. In this work, using the Van de Graaff accelerator the authors have explored different materials for filtering and reflecting neutron beams produced by irradiating a thick Li target with 1.8 to 2.5 MeV proton beams. However, since the yield and the maximum neutron energy emerging from the Li-7(p,n)Be-7 reaction increase with increase in the proton beam energy, there is a need for optimization of the proton energy versus filter and shielding requirements to obtain the desired epithermal neutron beam. The MCNP-4A computer code was used for the initial design studies that were verified with benchmark experiments using a proton recoil spectroscopy detection system. Comparison was also made between in phantom {sup 10}BF{sub 3} readings made at the BMRR and those made at the RARAF accelerator facility.

  18. ANALYSIS OF ACCELERATOR BASED NEUTRON SPECTRA FOR BNCT USING PROTON RECOIL SPECTROSCOPY

    SciTech Connect

    WIELOPOLSKI,L.; LUDEWIG,H.; POWELL,J.R.; RAPARIA,D.; ALESSI,J.G.; LOWENSTEIN,D.I.

    1998-11-06

    Boron Neutron Capture Therapy (BNCT) is a promising binary treatment modality for high-grade primary brain tumors (glioblastoma multiforme, GM) and other cancers. BNCT employs a boron-10 containing compound that preferentially accumulates in the cancer cells in the brain. Upon neutron capture by {sup 10}B energetic alpha particles and triton released at the absorption site kill the cancer cell. In order to gain penetration depth in the brain Fairchild proposed, for this purpose, the use of energetic epithermal neutrons at about 10 keV. Phase I/II clinical trials of BNCT for GM are underway at the Brookhaven Medical Research Reactor (BMRR) and at the MIT Reactor, using these nuclear reactors as the source for epithermal neutrons. In light of the limitations of new reactor installations, e.g. cost, safety and licensing, and limited capability for modulating the reactor based neutron beam energy spectra alternative neutron sources are being contemplated for wider implementation of this modality in a hospital environment. For example, accelerator based neutron sources offer the possibility of tailoring the neutron beams, in terms of improved depth-dose distributions, to the individual and offer, with relative ease, the capability of modifying the neutron beam energy and port size. In previous work new concepts for compact accelerator/target configuration were published. In this work, using the Van de Graaff accelerator the authors have explored different materials for filtering and reflecting neutron beams produced by irradiating a thick Li target with 1.8 to 2.5 MeV proton beams. However, since the yield and the maximum neutron energy emerging from the Li-7(p,n)Be-7 reaction increase with increase in the proton beam energy, there is a need for optimization of the proton energy versus filter and shielding requirements to obtain the desired epithermal neutron beam. The MCNP-4A computer code was used for the initial design studies that were verified with benchmark experiments using a proton recoil spectroscopy detection system. Comparison was also made between in phantom {sup 10}BF{sub 3} readings made at the BMRR and those made at the RARAF accelerator facility.

  19. Determination of aluminium in a "nimonic" alloy by activation with fast neutrons.

    PubMed

    Quigley, D A; Trussler, J W

    1969-03-01

    Aluminium at the 6% level was determined in a 15-component "nimonic" alloy with a coefficient of variation of +/-8.7% by using fast-neutron activation followed by pulse-height analysis of gamma-ray spectra. The possibility of determining chromium, iron, cobalt and manganese is discussed. PMID:18960521

  20. Measurements of High-Energy Neutrons Penetrated Through Concrete Shields Using Self-TOF, NE213, and Activation Detectors

    Microsoft Academic Search

    M. Sasaki; E. Kim; T. Nunomiya; T. Nakamura; N. Nakao; T. Shibata; Y. Uwamino; S. Ito; A. Fukumura

    2002-01-01

    Neutron energy spectra penetrated through concrete shields were measured using three types of high-energy neutron detectors: the Self-TOF detector, an NE213 organic liquid scintillator, and Bi and C activation detectors, which have been newly developed by a group at the Heavy-Ion Medical Accelerator in Chiba (HIMAC) facility of the National Institute of Radiological Sciences, Japan. Neutrons were generated by bombarding

  1. Proposed neutron activation analysis facilities in the Advanced Neutron Source

    SciTech Connect

    Robinson, L.; Dyer, F.F.; Emery, J.F.

    1990-01-01

    A number of analytical chemistry experimental facilities are being proposed for the Advanced Neutron Source. Experimental capabilities will include gamma-ray analysis and neutron depth profiling. This paper describes the various systems proposed and some of their important characteristics.

  2. Measurement of neutron energy spectra and neutron dose rates from 7Li(p,n)7Be reaction induced on thin LiF target

    NASA Astrophysics Data System (ADS)

    Atanackovic, Jovica; Matysiak, Witold; Dubeau, Jacques; Witharana, Sampath; Waker, Anthony

    2015-02-01

    The measurements of neutron energy spectra and neutron dose rates were performed using the KN Van de Graaff accelerator, located at the McMaster University Accelerator Laboratory (MAL). Protons were accelerated on the thin lithium fluoride (LiF) target and produced mono-energetic neutrons which were measured using three different spectrometers: Bonner Sphere Spectrometer (BSS), Nested Neutron Spectrometer (NNS), and Rotational Proton Recoil Spectrometer (ROSPEC). The purpose of this work is (1) measurement and quantification of low energy accelerator neutron fields in terms of neutron fluence and dose, (2) comparison of results obtained by three different instruments, (3) comparison of measurements with Monte Carlo simulations based on theoretical neutron yields from 7Li(p,n)7Be nuclear reaction, and (4) comparison of results obtained using different neutron spectral unfolding methods. The nominal thickness of the LiF target used in the experiment was 50 ?g /cm2, which corresponds to the linear thickness of 0.19 ?m and results in approximately 6 keV energy loss for the proton energies used in the experiment (2.2, 2.3, 2.4 and 2.5 MeV). For each of the proton energies, neutron fluence per incident proton charge was measured and several dosimetric quantities of interest in radiation protection were derived. In addition, theoretical neutron yield calculations together with the results of Monte Carlo (MCNP) modeling of the neutron spectra are reported. Consistent neutron fluence spectra were obtained with three detectors and good agreement was observed between theoretically calculated and measured neutron fluences and derived dosimetric quantities for investigated proton energies at 2.3, 2.4 and 2.5 MeV. In the case of 2.2 MeV, some plausibly explainable discrepancies were observed.

  3. Neural networks and the classification of active galactic nucleus spectra

    NASA Astrophysics Data System (ADS)

    Rawson, D. M.; Bailey, J.; Francis, P. J.

    1996-11-01

    The use of artificial neural networks (ANNs) as a classifier of digital spectra is investigated. Using both simulated and real data, it is shown that neural networks can be trained to discriminate between the spectra of different classes of active galactic nucleus (AGN) with realistic sample sizes and signal-to-noise ratios. By working in the Fourier domain, neural nets can classify objects without knowledge of their redshifts.

  4. Cross sections and differential spectra for reactions of 2-20 MeV neutrons on /sup nat/Ni

    SciTech Connect

    Blann, M.; Komoto, T.T.

    1988-01-01

    This report summarizes product yields, secondary n,p and (alpha) spectra, and ..gamma..-ray spectra calculated for incident neutrons of 2-20 MeV on /sup nat/Ni targets. Results are all from the code ALICE, using the version ALISO which does weighting of results for targets which are a mix of isotpoes. Where natural isotopic targets are involved, yields and n,p,..cap alpha.. sepctra will be reported weighted over isotopic yeilds. Gamma-ray spectra, however, will be reported for the most abundant isotope. We present product yields versus incident neutron energy, n,p,..cap alpha.. spectra versus incident neutron energy, and calculated ..gamma..-ray spectra

  5. Evaluation of Hylife-II and Sombrero using 175- and 566- group neutron transport and activation cross sections

    SciTech Connect

    Cullen, D; Latkowski, J; Sanz, J

    1999-06-18

    Recent modifications to the TART Monte Carlo neutron and photon transport code enable calculation of 566-group neutron spectra. This expanded group structure represents a significant improvement over the 50- and 175-group structures that have been previously available. To support use of this new capability, neutron activation cross section libraries have been created in the 175- and 566-group structures starting from the FENDL/A-2.0 pointwise data. Neutron spectra have been calculated for the first walls of the HYLIFE-II and SOMBRERO inertial fusion energy power plant designs and have been used in subsequent neutron activation calculations. The results obtained using the two different group structures are compared to each other as well as to those obtained using a 175-group version of the EAF3.1 activation cross section library.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Biological spectra analysis: Linking biological activity profiles to molecular structure

    PubMed Central

    Fliri, Anton F.; Loging, William T.; Thadeio, Peter F.; Volkmann, Robert A.

    2005-01-01

    Establishing quantitative relationships between molecular structure and broad biological effects has been a longstanding challenge in science. Currently, no method exists for forecasting broad biological activity profiles of medicinal agents even within narrow boundaries of structurally similar molecules. Starting from the premise that biological activity results from the capacity of small organic molecules to modulate the activity of the proteome, we set out to investigate whether descriptor sets could be developed for measuring and quantifying this molecular property. Using a 1,567-compound database, we show that percent inhibition values, determined at single high drug concentration in a battery of in vitro assays representing a cross section of the proteome, provide precise molecular property descriptors that identify the structure of molecules. When broad biological activity of molecules is represented in spectra form, organic molecules can be sorted by quantifying differences between biological spectra. Unlike traditional structure–activity relationship methods, sorting of molecules by using biospectra comparisons does not require knowledge of a molecule's putative drug targets. To illustrate this finding, we selected as starting point the biological activity spectra of clotrimazole and tioconazole because their putative target, lanosterol demethylase (CYP51), was not included in the bioassay array. Spectra similarity obtained through profile similarity measurements and hierarchical clustering provided an unbiased means for establishing quantitative relationships between chemical structures and biological activity spectra. This methodology, which we have termed biological spectra analysis, provides the capability not only of sorting molecules on the basis of biospectra similarity but also of predicting simultaneous interactions of new molecules with multiple proteins. PMID:15625110

  8. Measured microdosimetric spectra and therapeutic potential of boron neutron capture enhancement of 252Cf brachytherapy.

    PubMed

    Burmeister, J; Kota, C; Maughan, R L

    2005-09-01

    Californium-252 is a neutron-emitting radioisotope used as a brachytherapy source for radioresistant tumors. Presented here are microdosimetric spectra measured as a function of simulated site diameter and distance from applicator tube 252Cf sources. These spectra were measured using miniature tissue-equivalent proportional counters (TEPCs). An investigation of the clinical potential of boron neutron capture (BNC) enhancement of 252Cf brachytherapy is also provided. The absorbed dose from the BNC reaction was measured using a boron-loaded miniature TEPC. Measured neutron, photon and BNC absorbed dose components are provided as a function of distance from the source. In general, the absorbed dose results show good agreement with results from other measurement techniques. A concomitant boost to 252Cf brachytherapy may be provided through the use of the BNC reaction. The potential magnitude of this BNC enhancement increases with increasing distance from the source and is capable of providing a therapeutic gain greater than 30% at a distance of 5 cm from the source, assuming currently achievable boron concentrations. PMID:16137204

  9. Neutron activation cross sections on lead isotopes

    Microsoft Academic Search

    V. Semkova; P. Reimer; T. Altzitzoglou; A. J. M. Plompen; C. Quétel; S. Sudár; J. Vogl; A. J. Koning; S. M. Qaim; D. L. Smith

    2009-01-01

    The cross sections for the reactions Pb204(n,n'gamma)Pb204m, Pb204(n,2n)Pb203, Pb204(n,2n)Pb203m1, Pb204(n,3n)Pb202m, Pb206(n,3n)Pb204m, Pb206(n,alpha)Hg203, and Pb208(n,p)Tl208 were determined at the IRMM van de Graaff laboratory in the neutron energy range from 14 to 21 MeV. Both natural and enriched samples were irradiated with neutrons produced via the H3(d,n)He4 reaction. The induced activities were determined by gamma-ray spectrometry using a HPGe detector in

  10. Monte Carlo simulations of down-scattered neutron and knock-on deuteron spectra in deuterium-tritium capsule implosions

    NASA Astrophysics Data System (ADS)

    Zhao, Bin; Zheng, Jian

    2013-12-01

    A Monte Carlo particle tracking (MCPT) code has been developed and coupled to hydrodynamic simulations to generate and track primary and scattered neutrons in addition to scattered charged particles by post-processing. This code uses one dimensional (1-D) deuterium-tritium implosion profiles, and the computed down-scattered neutron and knock-on deuteron spectra are analyzed for different areal densities. The mixing effects on the spectra of down-scattered neutron and knock-on deuteron are also investigated. The implementation of the numerical scheme is analyzed, and the particle splitting technique is adopted, which is proven to efficiently reduce computational effort.

  11. Measured and calculated fast neutron spectra in a depleted uranium and lithium hydride shielded reactor

    NASA Technical Reports Server (NTRS)

    Lahti, G. P.; Mueller, R. A.

    1973-01-01

    Measurements of MeV neutron were made at the surface of a lithium hydride and depleted uranium shielded reactor. Four shield configurations were considered: these were assembled progressively with cylindrical shells of 5-centimeter-thick depleted uranium, 13-centimeter-thick lithium hydride, 5-centimeter-thick depleted uranium, 13-centimeter-thick lithium hydride, 5-centimeter-thick depleted uranium, and 3-centimeter-thick depleted uranium. Measurements were made with a NE-218 scintillation spectrometer; proton pulse height distributions were differentiated to obtain neutron spectra. Calculations were made using the two-dimensional discrete ordinates code DOT and ENDF/B (version 3) cross sections. Good agreement between measured and calculated spectral shape was observed. Absolute measured and calculated fluxes were within 50 percent of one another; observed discrepancies in absolute flux may be due to cross section errors.

  12. Model atmospheres and X-ray spectra of bursting neutron stars

    NASA Technical Reports Server (NTRS)

    Madej, Jerzy

    1991-01-01

    Model atmosphere equations are derived which correspond to plane-parallel nongray atmospheres of very hot neutron stars in hydrostatic and radiative equilibrium. The nonlinear transfer equation used implements an exact photon redistribution function which precisely traces even those scattering events having large photon-electron energy exchange. The numerical results thus obtained encompass tables of the surface fluxes for 20 model atmospheres whose T(eff) ranges from 6 to 30 million K. The spectra of high gravity models are virtually identical with the blackbody spectrum shifted toward higher energies, while models approaching the Eddington limit develop a large low-energy hump.

  13. Total body nitrogen analysis. [neutron activation analysis

    NASA Technical Reports Server (NTRS)

    Palmer, H. E.

    1975-01-01

    Studies of two potential in vivo neutron activation methods for determining total and partial body nitrogen in animals and humans are described. A method using the CO-11 in the expired air as a measure of nitrogen content was found to be adequate for small animals such as rats, but inadequate for human measurements due to a slow excretion rate. Studies on the method of measuring the induced N-13 in the body show that with further development, this method should be adequate for measuring muscle mass changes occurring in animals or humans during space flight.

  14. ENERGY DEPENDENCE OF FAST-NEUTRON ACTIVATION CROSS SECTIONS

    Microsoft Academic Search

    A. E. Johnsrud; M. G. Silbert; H. H. Barschall

    1959-01-01

    Fast-neutron capture cross sections of 24 nuclides ranging from A = 51 ; to A = 197 were measured by an activation method, in the neutron energy region ; from 0.15 to 6.2 Mev. The neutron energy spreads were of the order of 0.1 Mev so ; that cross sections averaged over many energy levels of the compound nucleus were

  15. Thermal neutron activation cross sections for Kr and Xe isotopes

    Microsoft Academic Search

    E. Kondaiah; N. Ranakumar; R. W. Fink

    1968-01-01

    Quinol-clathrates of Kr and Xe have been used as solid targets for neutron activation for the first time, and 16 (n, gamma) cross sections have been determined with thermal neutrons. The epithermal neutron contribution has been taken into account by irradiating Cd covered samples. Four isomer cross-section ratios for Xe isotopes and one for Kr have also been obtained. In

  16. Fast Neutron Activation Cross Section of Au197

    Microsoft Academic Search

    S. A. Cox

    1961-01-01

    The neutron activation cross section of gold was measured in the neutron range from 30-1500 kev. The absolute value of the cross section was based on the U235 fast fission cross section which was used for absolute neutron flux measurements from 200-1500 kev. For measurements below 200 kev, the B10(n, alpha) cross section was used for monitoring the neutron flux.

  17. Spectra

    NSDL National Science Digital Library

    Kaler, James B.

    Spectra is a website illustrating how astronomers use spectra to understand what stars are made of, their structures, and their evolution. The page begins with an introduction to the electromagnetic spectrum and then goes into detail about the properties of light. Then it discusses how matter both creates and destroys radiation. It goes on to interpret absorption and emission lines. The website ends with discussing how astronomers use spectra to understand stars, galaxies, and other objects in the universe.

  18. Detector-Response Correction of Two-Dimensional ?-Ray Spectra from Neutron Capture

    NASA Astrophysics Data System (ADS)

    Rusev, G.; Jandel, M.; Arnold, C. W.; Bredeweg, T. A.; Couture, A.; Mosby, S. M.; Ullmann, J. L.

    2015-05-01

    The neutron-capture reaction produces a large variety of ?-ray cascades with different ?-ray multiplicities. A measured spectral distribution of these cascades for each ?-ray multiplicity is of importance to applications and studies of ?-ray statistical properties. The DANCE array, a 4? ball of 160 BaF2 detectors, is an ideal tool for measurement of neutron-capture ?-rays. The high granularity of DANCE enables measurements of high-multiplicity ?-ray cascades. The measured two-dimensional spectra (?-ray energy, ?-ray multiplicity) have to be corrected for the DANCE detector response in order to compare them with predictions of the statistical model or use them in applications. The detector-response correction problem becomes more difficult for a 4? detection system than for a single detector. A trial and error approach and an iterative decomposition of ?-ray multiplets, have been successfully applied to the detector-response correction. Applications of the decomposition methods are discussed for two-dimensional ?-ray spectra measured at DANCE from ?-ray sources and from the 10B(n, ?) and 113Cd(n, ?) reactions.

  19. Neutron activation analysis in archaeological chemistry

    SciTech Connect

    Harbottle, G.

    1987-01-01

    Neutron activation analysis has proven to be a convenient way of performing the chemical analysis of archaeologically-excavated artifacts and materials. It is fast and does not require tedious laboratory operations. It is multielement, sensitive, and can be made nondestructive. Neutron activation analysis in its instrumental form, i.e., involving no chemical separation, is ideally suited to automation and conveniently takes the first step in data flow patterns that are appropriate for many taxonomic and statistical operations. The future will doubtless see improvements in the practice of NAA in general, but in connection with archaeological science the greatest change will be the filling, interchange and widespread use of data banks based on compilations of analytical data. Since provenience-oriented data banks deal with materials (obsidian, ceramics, metals, semiprecious stones, building materials and sculptural media) that participated in trade networks, the analytical data is certain to be of interest to a rather broad group of archaeologists. It is to meet the needs of the whole archaeological community that archaeological chemistry must now turn.

  20. Active and sterile neutrino mass effects on beta decay spectra

    SciTech Connect

    Boillos, Juan Manuel; Moya de Guerra, Elvira [Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, U. Complutense de Madrid, Av. Complutense s/n, E-28040, Madrid (Spain); Moreno, Oscar [Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, U. Complutense de Madrid, Av. Complutense s/n, E-28040, Madrid (Spain)

    2013-06-10

    We study the spectra of the emitted charged leptons in charge current weak nuclear processes to analyze the effect of neutrino masses. Standard active neutrinos are studied here, with masses of the order of 1 eV or lower, as well as sterile neutrinos with masses of a few keV. The latter are warm dark matter (WDM) candidates hypothetically produced or captured as small mixtures with the active neutrinos. We compute differential decay or capture rates spectra in weak charged processes of different nuclei ({sup 3}H, {sup 187}Re, {sup 107}Pd, {sup 163}Ho, etc) using different masses of both active and sterile neutrinos and different values of the mixing parameter.

  1. Cross sections and differential spectra for reactions of 2-20 MeV neutrons of /sup 27/Al

    SciTech Connect

    Blann, M.; Komoto, T.T.

    1988-01-01

    This report summarizes product yields, secondary n,p and ..cap alpha.. spectra, and ..gamma..-ray spectra calculated for incident neutrons of 2-20 MeV on /sup 27/Al targets. Results are all from the code ALICE, using the version ALISO which does weighting of results for targets which are a mix of isotopes. Where natural isotopic targets are involved, yields and n,p,..cap alpha.. spectra will be reported weighted over isotopic yields. Gamma-ray spectra, however, will be reported for the most abundant isotope.

  2. Measurement and prediction of neutron spectra in the Kalpakkam mini reactor (KAMINI).

    PubMed

    Mohapatra, D K; Mohanakrishnan, P

    2002-07-01

    Kalpakkam mini (KAMINI) reactor is the newest research reactor built in India. Operated at the Indira Gandhi Centre for Atomic Research, Kalpakkam, it has the unique distinction of being the only operating pool-type reactor in the world at present fuelled by 233U and aluminium alloy. Neutron spectra have been measured by the multi-foil irradiation method at the beam tube ends of this reactor. The spectra unfolding have been done, by using SAND-II computer code. Thus the total and thermal flux at the beam tube ends have been measured. The theoretical spectrum generated by the computer codes SMAXY and COMESH and WIMS cross-section data library was compared with the measured spectrum for one of the beam tubes and found to match well. A new 620-group cross-section data library generated at our centre was tested with SAND-II for the same set of measurements. Use of the new library results in slightly higher measured total fluxes and smoother spectra shapes. PMID:12137023

  3. Modeling and small-angle neutron scattering spectra of chromatin supernucleosomal structures at genome scale

    NASA Astrophysics Data System (ADS)

    Ilatovskiy, Andrey V.; Lebedev, Dmitry V.; Filatov, Michael V.; Grigoriev, Mikhail; Petukhov, Michael G.; Isaev-Ivanov, Vladimir V.

    2011-11-01

    Eukaryotic genome is a highly compacted nucleoprotein complex organized in a hierarchical structure based on nucleosomes. Detailed organization of this structure remains unknown. In the present work we developed algorithms for geometry modeling of the supernucleosomal chromatin structure and for computing distance distribution functions and small-angle neutron scattering (SANS) spectra of the genome-scale (˜106 nucleosomes) chromatin structure at residue resolution. Our physical nucleosome model was based on the mononucleosome crystal structure. A nucleosome was assumed to be rigid within a local coordinate system. Interface parameters between nucleosomes can be set for each nucleosome independently. Pair distance distributions were computed with Monte Carlo simulation. SANS spectra were calculated with Fourier transformation of weighted distance distribution; the concentration of heavy water in solvent and probability of H/D exchange were taken into account. Two main modes of supernucleosomal structure generation were used. In a free generation mode all interface parameters were chosen randomly, whereas nucleosome self-intersections were not allowed. The second generation mode (generation in volume) enabled spherical or cubical wall restrictions. It was shown that calculated SANS spectra for a number of our models were in general agreement with available experimental data.

  4. Measurements of neutron energy spectra from 7Li(p,n)7Be reaction with Bonner sphere spectrometer, Nested Neutron Spectrometer and ROSPEC.

    PubMed

    Atanackovic, J; Matysiak, W; Witharana, S; Dubeau, J; Waker, A J

    2014-10-01

    Neutron spectrometry measurements were carried out at the McMaster Accelerator Laboratory (MAL), which is equipped with a 3-MV Van de Graaff-type accelerator. Protons were accelerated onto a thick natural lithium target inducing the (7)Li(p,n)(7)Be threshold reaction. Depending on the proton energy, slightly different poly-energetic neutron fields were produced. Neutron spectra were measured at two incident proton energies: 2.15 and 2.24 MeV, which produced poly-energetic neutrons with maximum kinetic energies of 401 and 511 keV, respectively. Measurements were performed at a distance of 1.5 m from the target in the forward direction with three different instruments: Bonner sphere spectrometer, Nested Neutron Spectrometer and ROtational proton recoil SPECtrometer. PMID:24298169

  5. Energy Dependence of Fast-Neutron Activation Cross Sections

    Microsoft Academic Search

    A. E. Johnsrud; M. G. Silbert; H. H. Barschall

    1959-01-01

    Fast-neutron capture cross sections of 24 nuclides ranging from A=51 to A=197 have been measured by an activation method, in the neutron energy region from 0.15 to 6.2 Mev. The neutron energy spreads were of the order of 0.1 Mev so that cross sections averaged over many energy levels of the compound nucleus were measured. Activities induced in samples by

  6. The thermal neutron activation cross section of 105 Ru

    Microsoft Academic Search

    B. L. Sharma

    1960-01-01

    Summary  In order to calculate the thermal neutron activation cross section of105Ru, the enriched104Ru was exposed to a thermal neutron flux of 1.2·1014 neutrons cm?2s?1. After the decay of the 40-day activity of103Ru, the silver impurity was removed and the contributions from Co and Eu impurities were subtracted. The ?-ray energies and\\u000a the coincidence results were consistent with the previously established

  7. The dependence of build-up 233 U, 232 U, 233 Pa and fission products from ThO 2 irradiated in HFETR on integral thermal neutron fluxes and neutron spectra

    Microsoft Academic Search

    J. H. Zhang; B. R. Bao; Y. X. Xia; J. B. Zhu

    1987-01-01

    In this paper the dependence of build-up233U,232U,233Pa and fission products from ThO2 irradiated in HFETR on integral thermal neutron fluxes and neutron spectra have been investigated. The yields of all above nuclides in ThO2 increase with the increase of integral thermal neutron fluxes at different neutron spectra. The values of233U\\/232Th increase with the increases of th and decreases with the

  8. Neutron activation cross-section of zirconium-94

    Microsoft Academic Search

    1978-01-01

    The thermal neutron activation cross-section of94Zr was found to be 49.3±0.6 millibarns. It is shown that neutron activation analysis of Zr in silicate samples with a Zr\\/U\\u000a ratio<10 has considerable uncertainty due to fission contribution. A correction factor for the fission contribution has been\\u000a determined experimentally.

  9. Gamma-gamma coincidence spectrometer setup for neutron activation analysis and nuclear structure studies

    NASA Astrophysics Data System (ADS)

    Khang, Pham Dinh; Hai, N. X.; Tan, V. H.; Dien, N. N.

    2011-04-01

    The gamma-gamma coincidence spectrometer has been setup at the tangential neutron beam port of the Dalat Nuclear Research Reactor (DNRR) for neutron activation analysis and nuclear structure studies. The selected parameters were chosen by new method, and the quality of parameters was evaluated with peak area ratios of spectra which have been measured by two detectors in event-event coincidence mode. The experimental setup, its performance and analysis method using 60Co source and 35Cl( n,2?) 36Cl reaction are presented in this paper.

  10. Development of high flux thermal neutron generator for neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Vainionpaa, Jaakko H.; Chen, Allan X.; Piestrup, Melvin A.; Gary, Charles K.; Jones, Glenn; Pantell, Richard H.

    2015-05-01

    The new model DD110MB neutron generator from Adelphi Technology produces thermal (<0.5 eV) neutron flux that is normally achieved in a nuclear reactor or larger accelerator based systems. Thermal neutron fluxes of 3-5 · 107 n/cm2/s are measured. This flux is achieved using four ion beams arranged concentrically around a target chamber containing a compact moderator with a central sample cylinder. Fast neutron yield of ?2 · 1010 n/s is created at the titanium surface of the target chamber. The thickness and material of the moderator is selected to maximize the thermal neutron flux at the center. The 2.5 MeV neutrons are quickly thermalized to energies below 0.5 eV and concentrated at the sample cylinder. The maximum flux of thermal neutrons at the target is achieved when approximately half of the neutrons at the sample area are thermalized. In this paper we present simulation results used to characterize performance of the neutron generator. The neutron flux can be used for neutron activation analysis (NAA) prompt gamma neutron activation analysis (PGNAA) for determining the concentrations of elements in many materials. Another envisioned use of the generator is production of radioactive isotopes. DD110MB is small enough for modest-sized laboratories and universities. Compared to nuclear reactors the DD110MB produces comparable thermal flux but provides reduced administrative and safety requirements and it can be run in pulsed mode, which is beneficial in many neutron activation techniques.

  11. Mineral exploration and soil analysis using in situ neutron activation

    USGS Publications Warehouse

    Senftle, F.E.; Hoyte, A.F.

    1966-01-01

    A feasibility study has been made to operate by remote control an unshielded portable positive-ion accelerator type neutron source to induce activities in the ground or rock by "in situ" neutron irradiation. Selective activation techniques make it possible to detect some thirty or more elements by irradiating the ground for periods of a few minutes with either 3-MeV or 14-MeV neutrons. The depth of penetration of neutrons, the effect of water content of the soil on neutron moderation, gamma ray attenuation in the soil and other problems are considered. The analysis shows that, when exploring for most elements of economic interest, the reaction 2H(d,n)3He yielding ??? 3-MeV neutrons is most practical to produce a relatively uniform flux of neutrons of less than 1 keV to a depth of 19???-20???. Irradiation with high energy neutrons (??? 14 MeV) can also be used and may be better suited for certain problems. However, due to higher background and lower sensitivity for the heavy minerals, it is not a recommended neutron source for general exploration use. Preliminary experiments have been made which indicate that neutron activation in situ is feasible for a mineral exploration or qualititative soil analysis. ?? 1976.

  12. Neutron spectra as a function of angle at two meters from the Little Boy assembly

    SciTech Connect

    Griffith, R.V.; Huntzinger, C.J.; Thorngate, J.H.

    1984-07-02

    Measurements of neutron spectra produced by the Los Alamos National Laboratory (LANL) Little Boy replica assembly (Comet) were made with a combined multisphere and liquid scintillator system, that has been widely used at the Lawrence Livermore National Laboratory. The combined system was used for measurements at the side (90/sup 0/) and nose (0/sup 0/) of the assembly; additional measurements were made at 45/sup 0/ using only the liquid scintillator. Data were obtained at two meters from the center of the reactive region of the assembly, with good agreement between the multisphere and scintillator results. Comparison with liquid scintillator measurements performed by experimenters from the Canadian Defence Research Establishment, Ottawa (DREO) and calculations from LANL depended on the specific angle, obtaining the best agreement at 90/sup 0/. 32 references, 11 figures, 4 tables.

  13. Solar flare proton rigidity spectra deduced from cosmic ray neutron monitor observations

    NASA Technical Reports Server (NTRS)

    Lockwood, J. A.; Webber, W. R.; Hsieh, L.

    1974-01-01

    The solar flare proton rigidity spectra for several flares occurring between 1967 and 1972 have been deduced from the ground level cosmic ray neutron monitor observations. To obtain consistent agreement for all the ground level events (GLEs) analyzed, the specific yield functions of Lockwood and Webber (1967) must be reduced slightly below P = 1.6 GV. The typical spectral indices of solar cosmic rays deduced for GLEs vary from 4 to 6 if the differential spectrum is represented by KP to the minus gamma power. Only occasionally is the spectrum as steep as 8 or 9. The observed spectral index is independent of the magnitude of the integral solar proton flux above 1 GV.

  14. Displacement cross sections and PKA spectra: tables and applications. [Neutron damage energy cross sections to 20 MeV, primary knockon atom spectra to 15 MeV

    Microsoft Academic Search

    D. G. Doran; N. J. Graves

    1976-01-01

    Damage energy cross sections to 20 MeV are given for aluminum, vanadium, chromium, iron, nickel, copper, zirconium, niobium, molybdenum, tantalum, tungsten, lead, and 18Cr10Ni stainless steel. They are based on ENDF\\/B-IV nuclear data and the Lindhard energy partition model. Primary knockon atom (PKA) spectra are given for aluminum, iron, niobium, tantalum, and lead for neutron energies up to 15 MeV

  15. An investigation of the activation of water by DT fusion neutrons and some implications for fusion reactor technology

    Microsoft Academic Search

    Yujiro Ikeda; Yoshitomo Uno; Fujio Maekawa; Donald L. Smith; Itacil C. Gomes; Robert C. Ward; Anatoly A. Filatenkov

    1997-01-01

    Several fundamental aspects of the activation of water by neutrons in D-T fusion systems have been investigated in this work. The basic physical principles involved and the status of pertinent nuclear cross-section and radioactivity data were reviewed. The integral response of the dominant 16O(n,p)16N reaction was calculated using several evaluated differential cross-section representations and characteristic D-T fusion neutron spectra. The

  16. Neutron-encoded Signatures Enable Product Ion Annotation From Tandem Mass Spectra*

    PubMed Central

    Richards, Alicia L.; Vincent, Catherine E.; Guthals, Adrian; Rose, Christopher M.; Westphall, Michael S.; Bandeira, Nuno; Coon, Joshua J.

    2013-01-01

    We report the use of neutron-encoded (NeuCode) stable isotope labeling of amino acids in cell culture for the purpose of C-terminal product ion annotation. Two NeuCode labeling isotopologues of lysine, 13C615N2 and 2H8, which differ by 36 mDa, were metabolically embedded in a sample proteome, and the resultant labeled proteins were combined, digested, and analyzed via liquid chromatography and mass spectrometry. With MS/MS scan resolving powers of ?50,000 or higher, product ions containing the C terminus (i.e. lysine) appear as a doublet spaced by exactly 36 mDa, whereas N-terminal fragments exist as a single m/z peak. Through theory and experiment, we demonstrate that over 90% of all y-type product ions have detectable doublets. We report on an algorithm that can extract these neutron signatures with high sensitivity and specificity. In other words, of 15,503 y-type product ion peaks, the y-type ion identification algorithm correctly identified 14,552 (93.2%) based on detection of the NeuCode doublet; 6.8% were misclassified (i.e. other ion types that were assigned as y-type products). Searching NeuCode labeled yeast with PepNovo+ resulted in a 34% increase in correct de novo identifications relative to searching through MS/MS only. We use this tool to simplify spectra prior to database searching, to sort unmatched tandem mass spectra for spectral richness, for correlation of co-fragmented ions to their parent precursor, and for de novo sequence identification. PMID:24043425

  17. The Calibration of the DD Neutron Indium Activation Diagnostic

    NASA Astrophysics Data System (ADS)

    Song, Zifeng; Chen, Jiabin; Liu, Zhongjie; Zhan, Xiayu; Tang, Qi

    2015-04-01

    The indium activation diagnostic was calibrated using an accelerator neutron source to facilitate the diagnosis of deuterium-deuterium (DD) neutron yields of implosion experiments in the Shenguang-III facility. The scattered neutron background of the accelerator room was measured by placing a polypropylene shadow bar in front of the indium sample, so as to correct the calibrated factor of this activation diagnostic. The proper size of the shadow bar was given by Monte Carlo simulation. The calibration results showed that the scattered neutron background of the accelerator room was about 9% of the incident neutrons on the sample. Subtracting the portion induced by the neutron background, the calibrated factor for this sample condition was 4.52×10?7 counts/n with an uncertainty of 4.3%.

  18. SOURCES 4C : a code for calculating ([alpha],n), spontaneous fission, and delayed neutron sources and spectra.

    SciTech Connect

    Wilson, W. B. (William B.); Perry, R. T. (Robert T.); Shores, E. F. (Erik F.); Charlton, W. S. (William S.); Parish, Theodore A.; Estes, G. P. (Guy P.); Brown, T. H. (Thomas H.); Arthur, Edward D. (Edward Dana),; Bozoian, Michael; England, T. R.; Madland, D. G.; Stewart, J. E. (James E.)

    2002-01-01

    SOURCES 4C is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to radionuclide decay. The code is capable of calculating ({alpha},n) source rates and spectra in four types of problems: homogeneous media (i.e., an intimate mixture of a-emitting source material and low-Z target material), two-region interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material), three-region interface problems (i.e., a thin slab of low-Z target material sandwiched between {alpha}-emitting source material and low-Z target material), and ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 44 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 107 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code provides the magnitude and spectra, if desired, of the resultant neutron source in addition to an analysis of the'contributions by each nuclide in the problem. LASTCALL, a graphical user interface, is included in the code package.

  19. SOURCES 4A: A Code for Calculating (alpha,n), Spontaneous Fission, and Delayed Neutron Sources and Spectra

    SciTech Connect

    Madland, D.G.; Arthur, E.D.; Estes, G.P.; Stewart, J.E.; Bozoian, M.; Perry, R.T.; Parish, T.A.; Brown, T.H.; England, T.R.; Wilson, W.B.; Charlton, W.S.

    1999-09-01

    SOURCES 4A is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to the decay of radionuclides. The code is capable of calculating ({alpha},n) source rates and spectra in four types of problems: homogeneous media (i.e., a mixture of {alpha}-emitting source material and low-Z target material), two-region interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material), three-region interface problems (i.e., a thin slab of low-Z target material sandwiched between {alpha}-emitting source material and low-Z target material), and ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 43 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 89 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code outputs the magnitude and spectra of the resultant neutron source. It also provides an analysis of the contributions to that source by each nuclide in the problem.

  20. Diffusive properties of water in Artemia cysts as determined from quasi-elastic neutron scattering spectra.

    PubMed Central

    Trantham, E C; Rorschach, H E; Clegg, J S; Hazlewood, C F; Nicklow, R M; Wakabayashi, N

    1984-01-01

    Results have been obtained on the quasi-elastic spectra of neutrons scattered from pure water, a 20% agarose gel (hydration four grams H2O per gram of dry solid) and cysts of the brine shrimp Artemia for hydrations between 0.10 and 1.2 grams H2O per gram of dry solids. The spectra were interpreted using a two-component model that included contributions from the covalently bonded protons and the hydration water, and a mobile water fraction. The mobile fraction was described by a jump-diffusion correlation function for the translation motion and a simple diffusive orientational correlation function. The results for the line widths gamma (Q2) for pure water were in good agreement with previous measurements. The agarose results were consistent with NMR measurements that show a slightly reduced translational diffusion for the mobile water fraction. The Artemia results show that the translational diffusion coefficient of the mobile water fraction was greatly reduced from that of pure water. The line width was determined mainly by the rotational motion, which was also substantially reduced from the pure water value as determined from dielectric relaxation studies. The translational and rotational diffusion parameters were consistent with the NMR measurements of diffusion and relaxation. Values for the hydration fraction and the mean square thermal displacement [u2] as determined from the Q-dependence of the line areas were also obtained. PMID:6733243

  1. THE GAMMA-RAY SPECTRA PRODUCED BY INELASTIC FAST NEUTRON SCATTERING IN Mg, Al, Fe, Cu, Sn, AND Sb

    Microsoft Academic Search

    I. F. Barchuk; M. V. Pasechnik; Iu. A. Tsybulko

    1958-01-01

    Measurements were made of gamma -ray spectra in Mg, Al, Fe, Cu, Sn, and ; Sb produced by inelastic neutron scattering at 2.8 Mev. The measurements were ; carried out with a scintillation spectrometer with NaI crystal detector, ; photoelectron multiplier, and 50 channel pulse analyzer with a magnetic drum ; recorder. The spectrometer resolution was 6.5 to 7% for

  2. Intercomparison of U-238 deposits employed for neutron fluence determination in neutron activation cross section measurements

    Microsoft Academic Search

    J. W. Meadows; D. L. Smith; G. Winkler; H. Vonach; M. Wagner

    1989-01-01

    An intercomparison is made between a collection of five uranium deposits used for neutron fluence determination in neutron activation experiments at Argonne National Laboratory (ANL), Illinois, USA, and a single corresponding deposit from the Institut fuer Radiumforschung und Kernphysik (IRK), Vienna, Austria. The predominant uranium isotope in each of these deposits is U-238. Two methods were used in the study:

  3. Kermas for various substances averaged over the energy spectra of fast neutron therapy beams: A study in uncertainties

    SciTech Connect

    Awschalom, M.; Rosenberg, I.; Mravca, A.

    1983-07-01

    Kermas for various substances averaged over the energy spectra of fast neutron therapy beams, as well as ratios of average kermas relative to muscle, were calculated in an attempt to estimate the uncertainties introduced in these quantities by the poor knowledge of the elemental kerma functions, actual neutron energy spectra, and composition of tissues and other materials. Average kermas have uncertainties of the order of 7%--25%, while for ratios of average kermas the uncertainties are of the order of 2%--5% for materials of clinical interest. It is concluded that the ratio of average kerma of muscle to A-150 tissue-equivalent plastic should be 0.93 +- 0.03 for the new p+Be clinical neutron beams.

  4. Inter-pulse high-resolution gamma-ray spectra using a 14 MeV pulsed neutron generator

    USGS Publications Warehouse

    Evans, L.G.; Trombka, J.I.; Jensen, D.H.; Stephenson, W.A.; Hoover, R.A.; Mikesell, J.L.; Tanner, A.B.; Senftle, F.E.

    1984-01-01

    A neutron generator pulsed at 100 s-1 was suspended in an artificial borehole containing a 7.7 metric ton mixture of sand, aragonite, magnetite, sulfur, and salt. Two Ge(HP) gamma-ray detectors were used: one in a borehole sonde, and one at the outside wall of the sample tank opposite the neutron generator target. Gamma-ray spectra were collected by the outside detector during each of 10 discrete time windows during the 10 ms period following the onset of gamma-ray build-up after each neutron burst. The sample was measured first when dry and then when saturated with water. In the dry sample, gamma rays due to inelastic neutron scattering, neutron capture, and decay were counted during the first (150 ??s) time window. Subsequently only capture and decay gamma rays were observed. In the wet sample, only neutron capture and decay gamma rays were observed. Neutron capture gamma rays dominated the spectrum during the period from 150 to 400 ??s after the neutron burst in both samples, but decreased with time much more rapidly in the wet sample. A signal-to-noise-ratio (S/N) analysis indicates that optimum conditions for neutron capture analysis occurred in the 350-800 ??s window. A poor S/N in the first 100-150 ??s is due to a large background continuum during the first time interval. Time gating can be used to enhance gamma-ray spectra, depending on the nuclides in the target material and the reactions needed to produce them, and should improve the sensitivity of in situ well logging. ?? 1984.

  5. Analysis of BOP-F polymer by Neutron Activation

    Microsoft Academic Search

    Héctor René Vega-Carrillo; Eduardo Manzanares-Acuña; Víctor Martín Hernández-Dávila; Gema A. Mercado; Miguel Ángel Salas Luévano; Estudios Nucleares

    2006-01-01

    Neutron activation analysis has been utilized to determine the presence of undesirable elements in biocompatible osseous poly- mer fibers (BOP-F). This material is used as osseous tissue substitute in bone damage. The analysis was carried out using thermal neutrons. A short and long irradiation schemes were applied during analysis. Na and Br were found in the samples whose ratio is

  6. Vibrational spectra, structure and antioxidant activity of gossypol imine derivatives

    NASA Astrophysics Data System (ADS)

    Ilkevych, N. S.; Schroeder, G.; Rybachenko, V. I.; Chotiy, K. Y.; Makarova, R. A.

    2012-02-01

    The structures and tautomeric equilibria of natural polyphenol gossypol and four its imine derivatives were studied by FT-IR-, NMR-spectroscopy and quantum chemistry methods. It was shown that gossypol Schiff bases exist in solution as enamine-enamine tautomer and hydrazones as imine-imine tautomer. Infrared absorption spectra of studied compounds were simulated using the PM3 method. The fundamental vibrational frequencies were evaluated using various scale factors which yield a good agreement between observed and calculated frequencies. Free radical scavenging activity of gossypol and its imine derivatives was evaluated using DPPH method. Antioxidant activity of studied compounds was characterized. Gossypol hydrazones were shown to be more efficient, while Schiff base to be less efficient as antioxidants in comparison with gossypol itself.

  7. Neutron activation analysis at the Californium User Facility for Neutron Science

    SciTech Connect

    Martin, R.C.; Smith, E.H.; Glasgow, D.C. [Oak Ridge National Lab., TN (United States); Jerde, E.A. [Oak Ridge Research Inst., TN (United States); Marsh, D.L. [Univ. of Tennessee, Knoxville, TN (United States); Zhao, L. [Univ. of Texas, Austin, TX (United States)

    1997-12-01

    The Californium User Facility (CUF) for Neutron Science has been established to provide {sup 252}Cf-based neutron irradiation services and research capabilities including neutron activation analysis (NAA). A major advantage of the CUF is its accessibility and controlled experimental conditions compared with those of a reactor environment The CUF maintains the world`s largest inventory of compact {sup 252}Cf neutron sources. Neutron source intensities of {le} 10{sup 11} neutrons/s are available for irradiations within a contamination-free hot cell, capable of providing thermal and fast neutron fluxes exceeding 10{sup 8} cm{sup {minus}2} s{sup {minus}1} at the sample. Total flux of {ge}10{sup 9} cm{sup {minus}2} s{sup {minus}1} is feasible for large-volume irradiation rabbits within the {sup 252}Cf storage pool. Neutron and gamma transport calculations have been performed using the Monte Carlo transport code MCNP to estimate irradiation fluxes available for sample activation within the hot cell and storage pool and to design and optimize a prompt gamma NAA (PGNAA) configuration for large sample volumes. Confirmatory NAA irradiations have been performed within the pool. Gamma spectroscopy capabilities including PGNAA are being established within the CUF for sample analysis.

  8. Measurement of the Thick Target Be(p,n) Neutron Energy Spectra W. B. Howard

    E-print Network

    Massey, Thomas N.

    , the reaction is an important high intensity source of neutrons for many applications. Two promising medical applications are accelerator-based Boron Neutron Capture Therapy (BNCT) and Boron Neutron Capture Synovectomy that is the target with this treatment modality. Both BNCT and BNCS require a large flux of thermal neutrons

  9. Elemental analysis of combustion products by neutron activation

    SciTech Connect

    Heft, R.E.; Koszykowski, R.F.

    1980-01-01

    This paper gives a brief description of the neutron activation analysis method, which is being used to determine the elemental profile of combustion products from coal-fired power plants, oil shale retorting, and underground coal gasification. (DLC)

  10. Neutron activation studies and the effect of exercise on osteoporosis

    SciTech Connect

    Harrison, J.E.

    1984-01-01

    A technique is described to measure calcium content by in vivo neutron activation analysis of the trunk and upper thighs. In postmenopausal women, estrogen and calcium or fluoride reversed osteoporosis.

  11. Signatures of photon-axion conversion in the thermal spectra and polarization of neutron stars

    E-print Network

    Rosalba Perna; Wynn C. G. Ho; Licia Verde; Matthew van Adelsberg; Raul Jimenez

    2012-01-25

    Conversion of photons into axions under the presence of a strong magnetic field can dim the radiation from magnetized astrophysical objects. Here we perform a detailed calculation aimed at quantifying the signatures of photon-axion conversion in the spectra, light curves, and polarization of neutron stars (NSs). We take into account the energy and angle-dependence of the conversion probability and the surface thermal emission from NSs. The latter is computed from magnetized atmosphere models that include the effect of photon polarization mode conversion due to vacuum polarization. The resulting spectral models, inclusive of the general-relativistic effects of gravitational redshift and light deflection, allow us to make realistic predictions for the effects of photon to axion conversion on observed NS spectra, light curves, and polarization signals. We identify unique signatures of the conversion, such as an increase of the effective area of a hot spot as it rotates away from the observer line of sight. For a star emitting from the entire surface, the conversion produces apparent radii that are either larger or smaller (depending on axion mass and coupling strength) than the limits set by NS equations of state. For an emission region that is observed phase-on, photon-axion conversion results in an inversion of the plane of polarization with respect to the no-conversion case. While the quantitative details of the features that we identify depend on NS properties (magnetic field strength, temperature) and axion parameters, the spectral and polarization signatures induced by photon-axion conversion are distinctive enough to make NSs very interesting and promising probes of axion physics.

  12. Atmosphere Models of Magnetized Neutron Stars: QED Effects, Radiation Spectra, and Polarization Signals

    E-print Network

    Matthew van Adelsberg; Dong Lai

    2006-09-22

    Theoretical modeling of surface emission from magnetized neutron stars (NSs) requires proper treatment of QED effects, in particular the effect of photon mode conversion due to the ``vacuum resonance'' between plasma and vacuum polarization. Previous NS atmosphere models incorporated this effect approximately, using transfer equations for the photon modes which are inadequate near the vacuum resonance, particularly for field strengths around $B_l\\simeq 7\\times 10^{13}$ G, where the vacuum resonance occurs near the photosphere. In this paper, we provide an accurate treatment of the QED-induced mode conversion effect in NS atmosphere models, employing both the modal radiative transfer equations, coupled with an accurate mode conversion probability at the resonance, and the full evolution equations for the photon Stokes parameters. In doing so, we are able to quantitatively calculate the effects of vacuum polarization on the atmosphere emission spectra, beam patterns, and polarizations for the entire range of field strengths, $B=10^{12}-10^{15}$ G. We find that for NSs with $B\\ga 2 B_l$, vacuum polarization reduces the widths of spectral features, and softens the hard spectral tail typical of magnetized atmosphere models. For $B\\la B_l/2$, vacuum polarization does not change the emission spectra, but can significantly affect the polarization signals. We show that vacuum polarization induces a unique energy-dependent linear polarization signature, and that circular polarization can be generated in the magnetospheres of rapidly rotating NSs. We discuss the implications of our results for recent observations of thermally emitting isolated NSs and magnetars, as well as the prospects for future spectral and polarization observations.

  13. Measurement and calculation of fast-neutron spectra in water, graphite and lithium fluoride assemblies with a D-T neutron source

    NASA Astrophysics Data System (ADS)

    Sekimoto, H.; Lee, D.; Hojo, K.; Hojo, T.; Oishi, K.; Noura, T.; Ohtsuka, M.; Yamamuro, N.

    1985-08-01

    Scalar neutron spectra were measured with a miniature NE213 spectrometer at several positions in water, graphite and lithium fluoride assemblies, which were irradiated with D-T neutrons. The n-? discrimination was executed at each pulse height. The pulse height spectrum was unfolded to an energy spectrum with a modified FERDOR code. The measured spectrum was compared with a calculated spectrum using the MORSE-GG Monte Carlo code with the GICXFNS group cross-section set processed from the ENDF/B-IV and -V libraries. The measured spectrum in the graphite assembly showed fine structure, and each peak and valley corresponds to a level-inelastic scattering and total cross-section resonance peak. The measured spectrum in the lithium-fluoride assembly was rather smooth. In general, all the measured spectra agreed with the calculated ones in measurement and calculation error, though the error and oscillation of the unfolding were substantial.

  14. Uncertainty Quantification of Prompt Fission Neutron Spectra Using the Unified Monte Carlo Method

    NASA Astrophysics Data System (ADS)

    Rising, M. E.; Talou, P.; Prinja, A. K.

    2014-04-01

    In the ENDF/B-VII.1 nuclear data library, the existing covariance evaluations of the prompt fission neutron spectra (PFNS) were computed by combining the available experimental differential data with theoretical model calculations, relying on the use of a first-order linear Bayesan approach, the Kalman filter. This approach assumes that the theoretical model response to changes in input model parameters be linear about the a priori central values. While the Unified Monte Carlo (UMC) method remains a Bayesian approach, like the Kalman filter, this method does not make any assumption about the linearity of the model response or shape of the a posteriori distribution of the parameters. By sampling from a distribution centered about the a priori model parameters, the UMC method computes the moments of the a posteriori parameter distribution. As the number of samples increases, the statistical noise in the computed a posteriori moments decrease and an appropriately converged solution corresponding to the true mean of the a posteriori PDF results. The UMC method has been successfully implemented using both a uniform and Gaussian sampling distribution and has been used for the evaluation of the PFNS and its associated uncertainties. While many of the UMC results are similar to the first-order Kalman filter results, significant differences are shown when experimental data are excluded from the evaluation process. When experimental data are included a few small nonlinearities are present in the high outgoing energy tail of the PFNS.

  15. Neutron activation analysis of wheat samples.

    PubMed

    Galinha, C; Anawar, H M; Freitas, M C; Pacheco, A M G; Almeida-Silva, M; Coutinho, J; Maçãs, B; Almeida, A S

    2011-11-01

    The deficiency of essential micronutrients and excess of toxic metals in cereals, an important food items for human nutrition, can cause public health risk. Therefore, before their consumption and adoption of soil supplementation, concentrations of essential micronutrients and metals in cereals should be monitored. This study collected soil and two varieties of wheat samples-Triticum aestivum L. (Jordão/bread wheat), and Triticum durum L. (Marialva/durum wheat) from Elvas area, Portugal and analyzed concentrations of As, Cr, Co, Fe, K, Na, Rb and Zn using Instrumental Neutron Activation Analysis (INAA) to focus on the risk of adverse public health issues. The low variability and moderate concentrations of metals in soils indicated a lower significant effect of environmental input on metal concentrations in agricultural soils. The Cr and Fe concentrations in soils that ranged from 93-117 and 26,400-31,300mg/kg, respectively, were relatively high, but Zn concentration was very low (below detection limit <22mg/kg) indicating that soils should be supplemented with Zn during cultivation. The concentrations of metals in roots and straw of both varieties of wheat decreased in the order of K>Fe>Na>Zn>Cr>Rb>As>Co. Concentrations of As, Co and Cr in root, straw and spike of both varieties were higher than the permissible limits with exception of a few samples. The concentrations of Zn in root, straw and spike were relatively low (4-30mg/kg) indicating the deficiency of an essential micronutrient Zn in wheat cultivated in Portugal. The elemental transfer from soil to plant decreases with increasing growth of the plant. The concentrations of various metals in different parts of wheat followed the order: Root>Straw>Spike. A few root, straw and spike samples showed enrichment of metals, but the majority of the samples showed no enrichment. Potassium is enriched in all samples of root, straw and spike for both varieties of wheat. Relatively to the seed used for cultivation, Jordão presented higher transfer coefficients than Marialva, in particular for Co, Fe, and Na. The Jordão and Marialva cultivars accumulated not statistically significant different concentrations of different metals. The advantages of using INAA are the multielementality, low detection limits and use of solid samples (no need of digestion). PMID:21367605

  16. New technical solution for using the time-of-flight technique to measure neutron spectra

    E-print Network

    Taskaev, Sergey Yur'evich

    Institute of Nuclear Physics the source of epithermal neutrons based on a vacuum insulation tandem accelerator (VITA) for BNCT (Bayanov et al., 1998) is constructed and launched. The generation of neutrons a very small moderation of these neutrons is required for BNCT. The opportunity of realization

  17. Active Neutron-Based Interrogation System with D-D Neutron Source for Detection of Special Nuclear Materials

    NASA Astrophysics Data System (ADS)

    Takahashi, Y.; Misawa, T.; Yagi, T.; Pyeon, C. H.; Kimura, M.; Masuda, K.; Ohgaki, H.

    2015-10-01

    The detection of special nuclear materials (SNM) is an important issue for nuclear security. The interrogation systems used in a sea port and an airport are developed in the world. The active neutron-based interrogation system is the one of the candidates. We are developing the active neutron-based interrogation system with a D-D fusion neutron source for the nuclear security application. The D-D neutron source is a compact discharge-type fusion neutron source called IEC (Inertial-Electrostatic Confinement fusion) device which provides 2.45 MeV neutrons. The nuclear materials emit the highenergy neutrons by fission reaction. High-energy neutrons with energies over 2.45 MeV amount to 30% of all the fission neutrons. By using the D-D neutron source, the detection of SNMs is considered to be possible with the attention of fast neutrons if there is over 2.45 MeV. Ideally, neutrons at En>2.45 MeV do not exist if there is no nuclear materials. The detection of fission neutrons over 2.45 MeV are hopeful prospect for the detection of SNM with a high S/N ratio. In the future, the experiments combined with nuclear materials and a D-D neutron source will be conducted. Furthermore, the interrogation system will be numerically investigated by using nuclear materials, a D-D neutron source, and a steel container.

  18. Study of seleniferous soils using instrumental neutron activation analysis.

    PubMed

    Srivastava, Alok; Bains, G S; Acharya, R; Reddy, A V R

    2011-05-01

    Soil samples from the seleniferous region of Punjab State in India were analyzed by instrumental neutron activation analysis (INAA) using reactor neutrons and high resolution ?-ray spectrometry. Samples were collected from three different depths namely surface, root and geological bed zones. Concentrations of 15 elements including selenium and arsenic were determined by relative method. For comparison purposes, soil samples collected from a non-seleniferous region were also analyzed. PMID:21334213

  19. Measurements of 14 MeV Neutron Activation Cross Sections

    Microsoft Academic Search

    Rudolf Pepelnik; Bernd Anders; Beni M. Bahal

    1986-01-01

    In the neutron generator facility KORONA a neutron flux of 3 · 10 n\\/cms with an energy of 14.7 ± 0.3 MeV is available. A fast rabbit system transfers samples within 140 ms to the detector station. For activation analysis work a variety of reaction cross sections were determined:The reaction products have half-lives between 0.35 s and 64 d. For

  20. Reactor neutron activation analysis by a triple comparator method

    Microsoft Academic Search

    F. De Corte; A. Speecke; J. Hoste

    1969-01-01

    The single comparator method has been extended to a triple comparator method, using60Co,114m\\u000a In and198Au. In this technique, thek-ratios of the elements to be analyzed, now determined against the three comparators, are corrected for each new ratio of\\u000a thermal to epithermal reactor neutron flux. These flux ratios are calculated from the absolute activities of the three comparators.\\u000a The thermal neutron

  1. The determination of phosphorus by fast neutron activation analysis 

    E-print Network

    To-On, Maen

    1964-01-01

    THE DETERMXNATIQN OF PHOSPHORUS BY FAST NEUTRON ACTIVATION ANAXYSIS Thesis MAEN TO ON Submitted to the Graduate College of Texas ASM University in partial fulfillment of the reguirekents for the degree of MASTER OF SC XENCE May 1964 Major... subject, : chemistr'y THE DETERMXNATXON OF PHOSPHORUS BY FAST NEUTRON ACTXVATXON ANAXYSXS Thesis By MAEN TO ON Approved as to style and content by: (Chairman of Committee) (Memb of Committee) (Head of Department) (Member of Committee) May 1964 AC...

  2. Characterization of a nuclear reactor for neutron activation analysis

    Microsoft Academic Search

    D. A. Becker; P. D. LaFleur

    1974-01-01

    \\u000a Résumé  Ouelques caractéristiques du réacteur nucléaire NBSR utilisé pour l'analyse par activation neutronique ont été évaluées; les\\u000a techniques de mesure développées sont décrites. La discussion porte sur les caractéristiques suivantes: (1) le flux de neutrons\\u000a thermiques absorbés par le cadmium, (2) la distribution énergétique des neutrons mesurée grâce aux rapports cadmium et à des\\u000a détecteurs à seuil. L'excès de pression dans

  3. Comparison between the activation cross sections and integrated cross sections for the radiative capture of 14 MeV neutrons

    Microsoft Academic Search

    F. Cvelbar; A. Hudoklin; M. Potokar

    1970-01-01

    Cross sections obtained by the integration of prompt gamma-ray spectra from the radiative capture of 14 MeV neutrons in a series of elements are presented and compared wilh the activation cross sections reported by different authors. In contrast to the activation cross-section values, which are scattered between 1 mb and 10 mb as a function of mass number, the integrated

  4. Quantum Nature of Cyclotron Harmonics in Thermal Spectra of Neutron Stars

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    Some isolated neutron stars (NSs) show harmonically spaced absorption features in their thermal soft X-ray spectra. The interpretation of the features as a cyclotron line and its harmonics has been suggested, but the usual explanation of the harmonics as caused by relativistic effects fails because the relativistic corrections are extremely small in this case. We suggest that the features, known as quantum oscillations, correspond to the peaks in the energy dependence of the free-free opacity in a quantizing magnetic field. The peaks arise when the transitions to new Landau levels become allowed with increasing the photon energy; they are strongly enhanced by the square-root singularities in the phase-space density of quantum states in the case when the free (non-quantized) motion is effectively one dimensional. To explore observable properties of these quantum oscillations, we calculate models of hydrogen NS atmospheres with B ~ 1010-1011 G (i.e., electron cyclotron energy E c,e ~ 0.1-1 keV) and T eff = 1-3 MK. Such conditions are thought to be typical for the so-called central compact objects in supernova remnants, such as 1E 1207.4-5209 in PKS 1209-51/52. We show that observable features at the electron cyclotron harmonics form at moderately large values of the quantization parameter, b eff ? E c,e /kT eff ~= 0.5-20. The equivalent widths of the features can reach ~100-200 eV; they grow with increasing b eff and are lower for higher harmonics.

  5. PHOTON-PRODUCING AND NEUTRON ACTIVATION CROSS SECTIONS

    Microsoft Academic Search

    1959-01-01

    A tabulation of photon-preducing and neutron activation cross sections ; is presented primarily for use in analyzing secondary gamma emission and foil ; activities. It is intended to supplement the information currently available. ; Data are included for certain cross sections of the following elements: aluminum, ; beryllium, copper, iron, gold, lead, manganese, oxygen, and sulfur. (auth);

  6. Neutron Activation Cross Section of Technetium98

    Microsoft Academic Search

    Edward Anders

    1958-01-01

    The cross section for the reaction Tc98(n, gamma)Tc99m was determined by thermal neutron irradiation of a cyclotron-produced sample containing Tc95, Tc97m, Tc97g, Tc98, and Tc99. The degree of selectivity and background reduction required to permit an accurate measurement of the Tc98 content, 2.68+\\/-0.54 disintegrations per minute, was attained by means of beta-(740-Kev gamma) coincidence counting. At a thermal flux of

  7. Measurement of neutron spectra generated from bombardment of 4 to 24 MeV protons on a thick {sup 9}Be target and estimation of neutron yields

    SciTech Connect

    Paul, Sabyasachi; Sahoo, G. S.; Tripathy, S. P., E-mail: sam.tripathy@gmail.com, E-mail: tripathy@barc.gov.in; Sunil, C.; Bandyopadhyay, T. [Health Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sharma, S. C.; Ramjilal,; Ninawe, N. G.; Gupta, A. K. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2014-06-15

    A systematic study on the measurement of neutron spectra emitted from the interaction of protons of various energies with a thick beryllium target has been carried out. The measurements were carried out in the forward direction (at 0° with respect to the direction of protons) using CR-39 detectors. The doses were estimated using the in-house image analyzing program autoTRAK-n, which works on the principle of luminosity variation in and around the track boundaries. A total of six different proton energies starting from 4 MeV to 24 MeV with an energy gap of 4 MeV were chosen for the study of the neutron yields and the estimation of doses. Nearly, 92% of the recoil tracks developed after chemical etching were circular in nature, but the size distributions of the recoil tracks were not found to be linearly dependent on the projectile energy. The neutron yield and dose values were found to be increasing linearly with increasing projectile energies. The response of CR-39 detector was also investigated at different beam currents at two different proton energies. A linear increase of neutron yield with beam current was observed.

  8. Measurement of neutron spectra generated from bombardment of 4 to 24 MeV protons on a thick ?Be target and estimation of neutron yields.

    PubMed

    Paul, Sabyasachi; Sahoo, G S; Tripathy, S P; Sharma, S C; Ramjilal; Ninawe, N G; Sunil, C; Gupta, A K; Bandyopadhyay, T

    2014-06-01

    A systematic study on the measurement of neutron spectra emitted from the interaction of protons of various energies with a thick beryllium target has been carried out. The measurements were carried out in the forward direction (at 0° with respect to the direction of protons) using CR-39 detectors. The doses were estimated using the in-house image analyzing program autoTRAK_n, which works on the principle of luminosity variation in and around the track boundaries. A total of six different proton energies starting from 4 MeV to 24 MeV with an energy gap of 4 MeV were chosen for the study of the neutron yields and the estimation of doses. Nearly, 92% of the recoil tracks developed after chemical etching were circular in nature, but the size distributions of the recoil tracks were not found to be linearly dependent on the projectile energy. The neutron yield and dose values were found to be increasing linearly with increasing projectile energies. The response of CR-39 detector was also investigated at different beam currents at two different proton energies. A linear increase of neutron yield with beam current was observed. PMID:24985813

  9. A theoretical description of energy spectra and two-neutron separation energies for neutron-rich zirconium isotopes

    E-print Network

    J. E. Garcia-Ramos; K. Heyde; R. Fossion; V. Hellemans; S. De Baerdemacker

    2005-11-22

    Very recently the atomic masses of neutron-rich Zr isotopes, from $^{96}$Zr to $^{104}$Zr, have been measured with high precision. Using a schematic Interacting Boson Model (IBM) Hamiltonian, the evolution from spherical to deformed shapes along the chain of Zr isotopes, describing at the same time the excitation energies as well as the two-neutron separation energies, can be rather well reproduced. The interplay between phase transitions and configuration mixing of intruder excitations in this mass region is succinctly addressed.

  10. Possible differentiation of natal areas of North American waterfowl by neutron activation analysis

    USGS Publications Warehouse

    Devine, T.; Peterle, T.J.

    1968-01-01

    The possibility of using neutron activation analyses to differentiate sources of North American waterfowl was investigated by irradiating rectrices and wing bones of birds collected in several localities, and comparing the characteristic gamma-ray spectra. Canada goose rectrices from Oregon specimens could be distinguished from those taken in Wisconsin and Colorado based on higher levels of Mn. Mallard, black duck, and blue-winged teal wing bones from Wisconsin, Colorado, and New Brunswick could not be clearly identified as to locality from levels of Ca, Al, Na, Mn, and Cl.

  11. Neutron activation analysis for antimetabolites. [in food samples

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Determination of metal ion contaminants in food samples is studied. A weighed quantity of each sample was digested in a concentrated mixture of nitric, hydrochloric and perchloric acids to affect complete solution of the food products. The samples were diluted with water and the pH adjusted according to the specific analysis performed. The samples were analyzed by neutron activation analysis, polarography, and atomic absorption spectrophotometry. The solid food samples were also analyzed by neutron activation analysis for increased sensitivity and lower levels of detectability. The results are presented in tabular form.

  12. Measurement of fast neutron spectra from the interaction of 20 MeV protons with thick Be and C targets using CR-39 detector

    NASA Astrophysics Data System (ADS)

    Tripathy, S. P.; Paul, S.; Sahoo, G. S.; Suman, V.; Sunil, C.; Joshi, D. S.; Bandyopadhyay, T.

    2014-01-01

    Fast neutron spectral yield from the interaction of 20 MeV protons with thick Be and C targets are measured using CR-39 detectors. An image analysing program (autoTRAK_n) dedicated for neutron spectrum generation and dose estimation is developed based on the analysis of greylevel variations within each track and is used in the present study. The most important parameters for neutron spectrometry, i.e., track depth (length) and angle of all neutron-induced recoil tracks are determined using autoTRAK_n. The methodology is tested successfully to reproduce the spectra of some standard neutron sources which was reported earlier. In this study, autoTRAK_n is applied to generate neutron spectra from the above mentioned reactions, i.e., 9Be(p, n), 12C(p, n) and the neutron yields (total number of neutrons per projectile) for both the reactions are determined by folding the track density with the detector response. The dose equivalents and H?(10)-to-fluence ratios are also estimated. All these quantities are automatically obtained from the program. The neutron yield and the dose equivalent for 9Be(p, n) reaction are found to be about 4 times higher than that for 12C(p, n) reaction. The present methodology for neutron spectrum generation is found to be simple and effective and does not involve the complex spectrum unfolding procedures.

  13. Composite delayed neutron energy spectra of fissionable isotopes: Progress report, September 1, 1986-August 31, 1987

    SciTech Connect

    Couchell, G.P.; Schier, W.A.

    1987-01-01

    During this present contract period we have so far: (1) completed our studies of the time-dependent DN spectra following thermal fission of Pu-239; (2) measured the upper energy region of the DN spectra in four delay-time intervals following fast fission of U-238; and (3) measured the equilibrium DN spectra for U-235, U-238 and Pu-239 in the same upper energy region. In addition, we have developed an analytical technique for extracting Keepin six-group energy spectra from measured time-dependent spectra which largely overcomes the deficiencies of earlier methods of analysis. Four papers on our DN investigations have also been prepared for publication, two of which are already in print. By the end of this period we shall complete our measurements of the higher energy portion of the DN spectra for the remaining three U-238 time intervals and also for the equilibrium spectrum from fast fission of U-235.

  14. Measurements of neutron spectra underground relevant for remote detection of antineutrinos

    NASA Astrophysics Data System (ADS)

    Roecker, Caleb; Marleau, Peter; Gerling, Mark; Brennan, Jim

    2014-03-01

    High energy neutrons (>=100 MeV) created through muon spallation have the potential to bypass the shielding of large rare event detectors. As such they present an unknown background for the long range antineutrino detector WATCHMAN. We have built and are operating a capture-gate Gd-doped scintillation detector for measuring the background neutron spectrum at the Kimbalton Underground Research Facility (KURF). The detector measures the joint response of high energy neutron scatter events and neutron capture events allowing for a large dynamic range of neutron energies from 30 to hundreds of MeV. To amplify the number of neutrons for capture we use a lead multiplier in the center of the detector. At KURF we plan on taking measurements at ~300, 600, and 1450 m.w.e. Using the measured and Geant4 simulated response we plan on unfolding the neutron energy spectrum and rate as a function of overburden. This information will allow for the calculation of an important background for WATCHMAN and provide a lower bound on the depth requirement for future remote reactor monitoring deployments.

  15. PHITS simulations of absorbed dose out-of-field and neutron energy spectra for ELEKTA SL25 medical linear accelerator.

    PubMed

    Puchalska, Monika; Sihver, Lembit

    2015-06-21

    Monte Carlo (MC) based calculation methods for modeling photon and particle transport, have several potential applications in radiotherapy. An essential requirement for successful radiation therapy is that the discrepancies between dose distributions calculated at the treatment planning stage and those delivered to the patient are minimized. It is also essential to minimize the dose to radiosensitive and critical organs. With MC technique, the dose distributions from both the primary and scattered photons can be calculated. The out-of-field radiation doses are of particular concern when high energy photons are used, since then neutrons are produced both in the accelerator head and inside the patients. Using MC technique, the created photons and particles can be followed and the transport and energy deposition in all the tissues of the patient can be estimated. This is of great importance during pediatric treatments when minimizing the risk for normal healthy tissue, e.g. secondary cancer. The purpose of this work was to evaluate 3D general purpose PHITS MC code efficiency as an alternative approach for photon beam specification. In this study, we developed a model of an ELEKTA SL25 accelerator and used the transport code PHITS for calculating the total absorbed dose and the neutron energy spectra infield and outside the treatment field. This model was validated against measurements performed with bubble detector spectrometers and Boner sphere for 18?MV linacs, including both photons and neutrons. The average absolute difference between the calculated and measured absorbed dose for the out-of-field region was around 11%. Taking into account a simplification for simulated geometry, which does not include any potential scattering materials around, the obtained result is very satisfactorily. A good agreement between the simulated and measured neutron energy spectra was observed while comparing to data found in the literature. PMID:26057186

  16. PHITS simulations of absorbed dose out-of-field and neutron energy spectra for ELEKTA SL25 medical linear accelerator

    NASA Astrophysics Data System (ADS)

    Puchalska, Monika; Sihver, Lembit

    2015-06-01

    Monte Carlo (MC) based calculation methods for modeling photon and particle transport, have several potential applications in radiotherapy. An essential requirement for successful radiation therapy is that the discrepancies between dose distributions calculated at the treatment planning stage and those delivered to the patient are minimized. It is also essential to minimize the dose to radiosensitive and critical organs. With MC technique, the dose distributions from both the primary and scattered photons can be calculated. The out-of-field radiation doses are of particular concern when high energy photons are used, since then neutrons are produced both in the accelerator head and inside the patients. Using MC technique, the created photons and particles can be followed and the transport and energy deposition in all the tissues of the patient can be estimated. This is of great importance during pediatric treatments when minimizing the risk for normal healthy tissue, e.g. secondary cancer. The purpose of this work was to evaluate 3D general purpose PHITS MC code efficiency as an alternative approach for photon beam specification. In this study, we developed a model of an ELEKTA SL25 accelerator and used the transport code PHITS for calculating the total absorbed dose and the neutron energy spectra infield and outside the treatment field. This model was validated against measurements performed with bubble detector spectrometers and Boner sphere for 18?MV linacs, including both photons and neutrons. The average absolute difference between the calculated and measured absorbed dose for the out-of-field region was around 11%. Taking into account a simplification for simulated geometry, which does not include any potential scattering materials around, the obtained result is very satisfactorily. A good agreement between the simulated and measured neutron energy spectra was observed while comparing to data found in the literature.

  17. Neutron-Activation Soil Analysis in Ecological Investigations

    Microsoft Academic Search

    Sh. Khatamov; A. Zhumamuratov; B. Ibragimov; T. Tillaev

    2000-01-01

    The scientific-technical base and instrumentation for neutron-activation analysis has reached a level such that today such an analysis can be used to find more than 70 chemical elements in soil and other biological objects. The method is widely used in various fields of science and industry. At the same time, as noted in [1], unsolved methodological and metrological problems are

  18. Neutron activation analysis of some Neolithic copper objects

    E-print Network

    Agata Olariu

    1999-08-31

    93 items of Neolithic copper from National Museum of History from Bucharest, with the provenance from Moldavia region have been analyzed by neutron activation analysis. The results of the analysis provide the values of the concentrations for the series of the determined elements: Au, Ag, As, Cr, Co, Fe, Hg, Ni, Sb, Se, Sn and Zn.

  19. Multielement determination in river water by neutron activation analysis

    Microsoft Academic Search

    M. B. H. Al-Bedri; S. Al-Jobori

    1991-01-01

    Concentrations of Al, Br, Ca, Ce, Co, Cr, Eu, Fe, Hf, La, Lu, Mg, Mn, Na, Rb, Sc, Sm, Sr, Tb, Th, Ti, V, Yb, Zn, and Zr have been measured in Tigris and Euphrates river water, using neutron activation analysis in combination with preconcentration technique. River water samples were preconcentrated by evaporation at 70°C under atmospheric pressure. The samples

  20. Compilation of detection sensitivities in thermal-neutron activation

    NASA Technical Reports Server (NTRS)

    Wahlgren, M. A.; Wing, J.

    1967-01-01

    Detection sensitivities of the chemical elements following thermal-neutron activation have been compiled from the available experimental cross sections and nuclear properties and presented in a concise and usable form. The report also includes the equations and nuclear parameters used in the calculations.

  1. MANTRA: An Integral Reactor Physics Experiment to Infer the Neutron Capture Cross Sections of Actinides and Fission Products in Fast and Epithermal Spectra

    NASA Astrophysics Data System (ADS)

    Youinou, G.; Vondrasek, R.; Veselka, H.; Salvatores, M.; Paul, M.; Pardo, R.; Palmiotti, G.; Palchan, T.; Nusair, O.; Nimmagadda, J.; Nair, C.; Murray, P.; Maddock, T.; Kondrashev, S.; Kondev, F. G.; Jones, W.; Imel, G.; Glass, C.; Fonnesbeck, J.; Berg, J.; Bauder, W.

    2014-05-01

    This paper presents an update of an on-going collaborative INL-ANL-ISU integral reactor physics experiment whose objective is to infer the effective neutron capture cross sections for most of the actinides of importance for reactor physics and fuel cycle studies in both fast and epithermal spectra. Some fission products are also being considered. The principle of the experiment is to irradiate very pure actinide samples in the Advanced Test Reactor at INL and, after a given time, determine the amount of the different transmutation products. The determination of the nuclide densities before and after neutron irradiation together with the neutron fluence will allow inference of effective neutron capture cross-sections in different neutron spectra.

  2. Phonon self-energy and origin of anomalous neutron scattering spectra in SnTe and PbTe thermoelectrics

    SciTech Connect

    Li, Chen [ORNL] [ORNL; Ma, Jie [ORNL] [ORNL; May, Andrew F [ORNL] [ORNL; Cao, Huibo [ORNL] [ORNL; Christianson, Andrew D [ORNL] [ORNL; Ehlers, Georg [ORNL] [ORNL; Singh, David J [ORNL] [ORNL; Sales, Brian C [ORNL] [ORNL; Delaire, Olivier A [ORNL] [ORNL

    2014-01-01

    The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering (INS) and first-principles calculations. The experiments show that, surprisingly, although SnTe is closer to the ferroelectric instability, phonon spectra in PbTe exhibit a more anharmonic character. This behavior is reproduced in first-principles calculations of the temperature-dependent phonon self-energy. Our simulations reveal how the nesting of phonon dispersions induces prominent features in the self-energy, which account for the measured INS spectra and their temperature dependence. We establish that the phase-space for three-phonon scattering processes, rather than just the proximity to the lattice instability, is the mechanism determining the complex spectrum of the transverse-optical ferroelectric mode.

  3. Phonon self-energy and origin of anomalous neutron scattering spectra in SnTe and PbTe thermoelectrics

    NASA Astrophysics Data System (ADS)

    Li, Chen; Hellman, Olle; Ma, Jie; May, Andrew; Chen, Xin; Singh, David; Sales, Brian; Cao, Huibo; Christianson, Andrew; Ehlers, Georg; Delaire, Olivier

    2014-03-01

    The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering and first-principles calculations. The experiments show that, surprisingly, although SnTe is closer to the ferroelectric instability, phonon spectra in PbTe show a more anharmonic character. This behavior is reproduced in first-principles calculations of the temperature-dependent phonon self-energy. Our simulations reveal how the nesting of phonon dispersions induces prominent features in the self-energy, which account for the measured energy spectra and their temperature dependence. The contributions to the complex features of the transverse-optic ferroelectric mode from phase-space for three-phonon scattering processes and the lattice instability are compared. We acknowledge funding from the US DOE, Office of Basic Energy Sciences, Materials Science and Engineering Division, and from the S3TEC Energy Frontier Research Center, DOE DE-SC0001299.

  4. Phonon self-energy and origin of anomalous neutron scattering spectra in SnTe and PbTe thermoelectrics.

    PubMed

    Li, C W; Hellman, O; Ma, J; May, A F; Cao, H B; Chen, X; Christianson, A D; Ehlers, G; Singh, D J; Sales, B C; Delaire, O

    2014-05-01

    The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering (INS) and first-principles calculations. The experiments show that, surprisingly, although SnTe is closer to the ferroelectric instability, phonon spectra in PbTe exhibit a more anharmonic character. This behavior is reproduced in first-principles calculations of the temperature-dependent phonon self-energy. Our simulations reveal how the nesting of phonon dispersions induces prominent features in the self-energy, which account for the measured INS spectra and their temperature dependence. We establish that the phase space for three-phonon scattering processes, combined with the proximity to the lattice instability, is the mechanism determining the complex spectrum of the transverse-optic ferroelectric mode. PMID:24836255

  5. Phonon Self-Energy and Origin of Anomalous Neutron Scattering Spectra in SnTe and PbTe Thermoelectrics

    NASA Astrophysics Data System (ADS)

    Li, C. W.; Hellman, O.; Ma, J.; May, A. F.; Cao, H. B.; Chen, X.; Christianson, A. D.; Ehlers, G.; Singh, D. J.; Sales, B. C.; Delaire, O.

    2014-05-01

    The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering (INS) and first-principles calculations. The experiments show that, surprisingly, although SnTe is closer to the ferroelectric instability, phonon spectra in PbTe exhibit a more anharmonic character. This behavior is reproduced in first-principles calculations of the temperature-dependent phonon self-energy. Our simulations reveal how the nesting of phonon dispersions induces prominent features in the self-energy, which account for the measured INS spectra and their temperature dependence. We establish that the phase space for three-phonon scattering processes, combined with the proximity to the lattice instability, is the mechanism determining the complex spectrum of the transverse-optic ferroelectric mode.

  6. Copper activation deuterium-tritium neutron yield measurements at the National Ignition Facility

    E-print Network

    Copper activation deuterium-tritium neutron yield measurements at the National Ignition Facility G://rsi.aip.org/about/rights_and_permissions #12;REVIEW OF SCIENTIFIC INSTRUMENTS 83, 10D918 (2012) Copper activation deuterium-tritium neutron

  7. Neutron activation analysis in radioactive waste management studies

    SciTech Connect

    Landsberger, S.; Foltz, K. [Dept. of Nuclear Engineering Illinois, Urbana, IL (United States)

    1996-10-01

    Over the past several years we have employed various aspects in neutron activation analysis in experimental radioactive waste management studies, primarily in environmental restoration and laboratory clean-up. These investigations have included the use of activation products in the study of zirconium solvent extraction, evaporation technology, magnetically assisted chemical separation and separation of americium in liquid scintillation cocktails. A detailed talk will focus on the various methods used.

  8. Analysis of accelerator based neutron spectra for BNCT using proton recoil spectroscopy

    Microsoft Academic Search

    L. Wielopolski; H. Ludewig; J. R. Powell; D. Raparia; J. G. Alessi; D. I. Lowenstein

    1999-01-01

    Boron Neutron Capture Therapy (BNCT) is a promising binary treatment modality for high-grade primary brain tumors (glioblastoma multiforme, GM) and other cancers. BNCT employs a boron-10 containing compound that preferentially accumulates in the cancer cells in the brain. Upon neutron capture by ¹°B energetic alpha particles and triton released at the absorption site kill the cancer cell. In order to

  9. ANALYSIS OF ACCELERATOR BASED NEUTRON SPECTRA FOR BNCT USING PROTON RECOIL SPECTROSCOPY

    Microsoft Academic Search

    L. WIELOPOLSKI; H. LUDEWIG; J. R. POWELL; D. RAPARIA; J. G. ALESSI; D. I. LOWENSTEIN

    1998-01-01

    Boron Neutron Capture Therapy (BNCT) is a promising binary treatment modality for high-grade primary brain tumors (glioblastoma multiforme, GM) and other cancers. BNCT employs a boron-10 containing compound that preferentially accumulates in the cancer cells in the brain. Upon neutron capture by ¹°B energetic alpha particles and triton released at the absorption site kill the cancer cell. In order to

  10. Active Interrogation Using Electronic Neutron Generators for Nuclear Safeguards Applications

    SciTech Connect

    David L. Chichester; Edward H. Seabury

    2008-08-01

    Active interrogation, a measurement technique which uses a radiation source to probe materials and generate unique signatures useful for characterizing those materials, is a powerful tool for assaying special nuclear material. The most commonly used technique for performing active interrogation is to use an electronic neutron generator as the probe radiation source. Exploiting the unique operating characteristics of these devices, including their monoenergetic neutron emissions and their ability to operate in pulsed modes, presents a number of options for performing prompt and delayed signature analyses using both photon and neutron sensors. A review of literature in this area shows multiple applications of the active neutron interrogation technique for performing nuclear nonproliferation measurements. Some examples include measuring the plutonium content of spent fuel, assaying plutonium residue in spent fuel hull claddings, assaying plutonium in aqueous fuel reprocessing process streams, and assaying nuclear fuel reprocessing facility waste streams to detect and quantify fissile material. This paper discusses the historical use of this technique and examines its context within the scope and challenges of next-generation nuclear fuel cycles and advanced concept nuclear fuel cycle facilities.

  11. Prototyping an Active Neutron Veto for SuperCDMS

    E-print Network

    Calkins, Robert

    2015-01-01

    Neutrons, originating cosmogenically or from radioactive decays, can produce signals in dark matter detectors that are indistinguishable from Weakly Interacting Massive Particles (WIMPs). To combat this background for the SuperCDMS SNOLAB experiment, we are investigating designs for an active neutron veto within the constrained space of the compact SuperCDMS passive shielding. The current design employs an organic liquid scintillator mixed with an agent to enhance thermal neutron captures, with the scintillation light collected using wavelength-shifting fibers and read out by silicon photo-multipliers. We will describe the proposed veto and its predicted efficiency in detail and give some recent results from our R&D and prototyping efforts.

  12. Analysis of active neutron multiplicity data for Y-12 skull oxide samples

    Microsoft Academic Search

    M. S. Krick; N. Ensslin; R. N. Ceo; P. K. May

    1996-01-01

    Previous work on active neutron multiplicity measurements and analyses is summarized. New active multiplicity measurements are described for samples of Y-12 skull oxide using an Active Well Coincidence Counter and MSR4 multiplicity electronics. Neutron multiplication values for the samples were determined from triples\\/doubles ratios. Neutron multiplication values were also obtained from Monte Carlo calculations using the MCNP code and the

  13. Detection sensitivities in 3-8 MeV neutron activation

    NASA Technical Reports Server (NTRS)

    Wahlgren, M. A.; Wing, J.

    1968-01-01

    Study of detection sensitivities of 73 radioactive elements using fast unmoderated neutrons includes experiments for irradiation, cooling and counting conditions. The gamma ray emission spectra is used to identify the unknown material.

  14. Neutron activation analysis applied to perspiration electrolytes

    E-print Network

    McAndrew, Robert Gavin

    1969-01-01

    NaEDTRON ACTIVATION ANALYSIS APPLIED TO PERSPIPATXO & ELECTROLYTES A Thesis 11OBPRT GAVIN I'kANDREN III 'r ha~it teS tc th. Grn. '. ate ColleGe of Teens '. V:1 University in parti" 1 fa] fill sent oi he zemi iree. -ent for the c'agree o. Y...

  15. Determination of the internal structure of neutron stars from gravitational wave spectra

    E-print Network

    L. K. Tsui; P. T. Leung; J. Wu

    2006-10-20

    In this paper the internal structure of a neutron star is shown to be inferrable from its gravitational-wave spectrum. Iteratively applying the inverse scheme of the scaled coordinate logarithmic perturbation method for neutron stars proposed by Tsui and Leung [Astrophys. J. {\\bf 631}, 495 (2005)], we are able to determine the mass, the radius and the mass distribution of a star from its quasi-normal mode frequencies of stellar pulsation. In addition, accurate equation of state of nuclear matter can be obtained from such inversion scheme. Explicit formulas for the case of axial $w$-mode oscillation are derived here and numerical results for neutron stars characterized by different equations of state are shown.

  16. Rainbow-Like Spectra with a CD: An Active-Learning

    E-print Network

    Planin?iè, Gorazd

    Rainbow-Like Spectra with a CD: An Active-Learning Exercise G. Planins v ic v , University and transmission, and rainbow-like spectra to a large lecture hall of 200­300 students. He also described how rainbow-like spec- tra; and 2. a qualitative explanation of surprising results of those explorations

  17. MEASUREMENTS OF NEUTRON SPECTRA IN 0.8-GEV AND 1.6-GEV PROTON-IRRADIATED<2 OF 2>NA THICK TARGETS

    SciTech Connect

    Titarenko, Y. E. (Yury E.); Batyaev, V. F. (Vyacheslav F.); Zhivun, V. M. (Valery M.); Koldobsky, A. B. (Aleksander B.); Mulambetov, R. D. (Ruslan D.); Fischenko, D. V. (Dmitry V.); Smirnov, G. N. (Gennady N.); Mashnik, S. G. (Stepan G.); Prael, R. E. (Richard E.); Yasuda, H.; Sierk, A. J. (Arnold J.)

    2001-01-01

    Measurements of neutron spectra in W, and Na targets irradiated by 0.8 GeV and 1.6 GeV protons are presented. Measurements were made by the TOF techniques using the proton beam from ITEP U-10 synchrotron. Neutrons were detected with BICRON-511 liquid scintillator-based detectors. The neutron detection efficiency was calculated via the SCINFUL and CECIL codes. The W results are compared with the similar data obtained elsewhere. The measured neutron spectra are compared with the LAHET and CEM2k code simulations results. Attempt is made to explain some observed disagreements between experiments and simulations. The presented results are of interest both in terms of nuclear data buildup and as a benchmark of the up-to-date predictive power of the simulation codes used in designing the hybrid accelerator-driven system (ADS) facilities with sodium-cooled tungsten targets.

  18. Determination of proton and neutron spectra in the LANSCE spallation irradiation facility

    Microsoft Academic Search

    M. R. James; S. A. Maloy; W. F. Sommer; M. M. Fowler; D. Dry; P. D. Ferguson; G. Mueller; R. K. Corzine

    1999-01-01

    Materials samples were recently irradiated in the Los Alamos Radiation Effects Facility (LASREF) at the Los Alamos Neutron Science Center (LANSCE) to provide data for the Accelerator Production of Tritium (APT) project on the effect of irradiation on the mechanical and physical properties of materials. The targets were configured to expose samples to a variety of radiation environments including, high-energy

  19. Measured and Calculated Neutron Spectra and Dose Equivalent Rates at High Altitudes; Relevance to SST Operations and Space Research

    NASA Technical Reports Server (NTRS)

    Foelsche, T.; Mendell, R. B.; Wilson, J. W.; Adams, R. R.

    1974-01-01

    Results of the NASA Langley-New York University high-altitude radiation study are presented. Measurements of the absorbed dose rate and of secondary fast neutrons (1 to 10 MeV energy) during the years 1965 to 1971 are used to determine the maximum radiation exposure from galactic and solar cosmic rays of supersonic transport (SST) and subsonic jet occupants. The maximum dose equivalent rates that the SST crews might receive turn out to be 13 to 20 percent of the maximum permissible dose rate (MPD) for radiation workers (5 rem/yr). The exposure of passengers encountering an intense giant-energy solar particle event could exceed the MPD for the general population (0.5 rem/yr), but would be within these permissible limits if in such rare cases the transport descends to subsonic altitude; it is in general less than 12 percent of the MPD. By Monte Carlo calculations of the transport and buildup of nucleons in air for incident proton energies E of 0.02 to 10 GeV, the measured neutron spectra were extrapolated to lower and higher energies and for galactic cosmic rays were found to continue with a relatively high intensity to energies greater than 400 MeV, in a wide altitude range. This condition, together with the measured intensity profiles of fast neutrons, revealed that the biologically important fast and energetic neutrons penetrate deep into the atmosphere and contribute approximately 50 percent of the dose equivalant rates at SST and present subsonic jet altitudes.

  20. Development of a new deuterium-deuterium (D-D) neutron generator for prompt gamma-ray neutron activation analysis.

    PubMed

    Bergaoui, K; Reguigui, N; Gary, C K; Brown, C; Cremer, J T; Vainionpaa, J H; Piestrup, M A

    2014-12-01

    A new deuterium-deuterium (D-D) neutron generator has been developed by Adelphi Technology for prompt gamma neutron activation analysis (PGNAA), neutron activation analysis (NAA), and fast neutron radiography. The generator makes an excellent fast, intermediate, and thermal neutron source for laboratories and industrial applications that require the safe production of neutrons, a small footprint, low cost, and small regulatory burden. The generator has three major components: a Radio Frequency Induction Ion Source, a Secondary Electron Shroud, and a Diode Accelerator Structure and Target. Monoenergetic neutrons (2.5MeV) are produced with a yield of 10(10)n/s using 25-50mA of deuterium ion beam current and 125kV of acceleration voltage. The present study characterizes the performance of the neutron generator with respect to neutron yield, neutron production efficiency, and the ionic current as a function of the acceleration voltage at various RF powers. In addition the Monte Carlo N-Particle Transport (MCNP) simulation code was used to optimize the setup with respect to thermal flux and radiation protection. PMID:25305524

  1. The epithermal neutron flux distribution in a nuclear reactor and its effect on epithermal neutron activation analysis

    Microsoft Academic Search

    T. Bereznai; T. D. Mac Mahon

    1978-01-01

    The shape of the epithermal neutron energy distribution has been determined in two irradiation positions of the University\\u000a of London CONSORT II reactor. The method applied involves cadmium ratio measurements using a series of resonance detectors.\\u000a Principles of the method and some considerations relative to epithermal neutron activation analysis in connection with the\\u000a deviation of the epithermal neutron flux distribution

  2. Accelerator measurement of the energy spectra of neutrons emitted in the interaction of 3-GeV protons with several elements

    NASA Technical Reports Server (NTRS)

    Nalesnik, W. J.; Devlin, T. J.; Merker, M.; Shen, B. S. P.

    1972-01-01

    The application of time of flight techniques for determining the shapes of the energy spectra of neutrons between 20 and 400 MeV is discussed. The neutrons are emitted at 20, 34, and 90 degrees in the bombardment of targets by 3 GeV protons. The targets used are carbon, aluminum, cobalt, and platinum with cylindrical cross section. Targets being bombarded are located in the internal circulating beam of a particle accelerator.

  3. Obsidian sources characterized by neutron-activation analysis.

    PubMed

    Gordus, A A; Wright, G A; Griffin, J B

    1968-07-26

    Concentrations of elements such as manganese, scandium, lanthanum, rubidium, samarium, barium, and zirconium in obsidian samples from different flows show ranges of 1000 percent or more, whereas the variation in element content in obsidian samples from a single flow appears to be less than 40 percent. Neutron-activation analysis of these elements, as well as of sodium and iron, provides a means of identifying the geologic source of an archeological artifact of obsidian. PMID:17776740

  4. Diagnostic Application of Absolute Neutron Activation Analysis in Hematology

    SciTech Connect

    Zamboni, C.B.; Oliveira, L.C.; Dalaqua, L. Jr.

    2004-10-03

    The Absolute Neutron Activation Analysis (ANAA) technique was used to determine element concentrations of Cl and Na in blood of healthy group (male and female blood donators), select from Blood Banks at Sao Paulo city, to provide information which can help in diagnosis of patients. This study permitted to perform a discussion about the advantages and limitations of using this nuclear methodology in hematological examinations.

  5. Mechanistic analysis of loft pulsed neutron activation data

    SciTech Connect

    Perez-Griffo, M.L.; Block, R.C.; Lahey, R.T. Jr.

    1981-01-01

    Pulsed Neutron Activation (PNA) is a technique for measuring mass-weighted flow velocities without perturbing the flow. Monte Carlo PNA tagging and Monte Carlo detection calculations of the irradiated fluid with the transport of the irradiated fluid are used to predict the time spectrum in a PNA measurement. This mechanistic method has been used to analyze recent LOFT PNA measurements of single-phase water flowing in a 14-in. (0.35 m) schedule 160 steel pipe.

  6. An application of neutron activation analysis to biological materials

    Microsoft Academic Search

    T. Yamaguchi; M. Bando; A. Nakajima; M. Terai; M. Suzuki-Yasumoto

    1980-01-01

    Fourteen trace elements (short-lived nuclides: Al, Br, Cu, Mn and V; long-lived nuclides: Ag, Au, Cd, Co, Cr, Fe, Sc, Se and\\u000a Zn) in human eye tissues are determined simultaneously by non-destructive neutron activation analysis. The quantity of Al,\\u000a Br, Fe, Se and Zn in the eye tissues (about 1 to more than 10 ?g\\/g dry weight tissue) seems to

  7. Determination of indium in standard rocks by neutron activation analysis.

    PubMed

    Johansen, O; Steinnes, E

    1966-08-01

    A rapid neutron activation method for the determination of indium in rocks, based on 54 min (116m)In, is described. The method has been applied to a series of geochemical standards including granite G-1 and diabase W-1. The precision is better than +/- 5% for samples containing more than 5 x 10(-10)g indium. Good agreement with previously published values for G-1 and W-1 has been obtained. PMID:18959988

  8. Neutron activation analysis of extractable organohalogens in milk from China

    Microsoft Academic Search

    Weike Zhong; Diandou Xu; Zhifang Chai; Xueying Mao

    2004-01-01

    Instrumental neutron activation analysis (INAA) has been used for the determination of extractable organohalogens (EOX) in\\u000a milk. The detection limits are 50 ng, 8 ng and 3.5 ng for Cl, Br and I, respectively. The EOX concentrations in milk samples\\u000a from various regions of China were determined. Meanwhile, organochlorine pesticides residues were detected by gas chromatography.\\u000a The concentrations of the

  9. Neutron activation analysis of organohalogens in Chinese human hair

    Microsoft Academic Search

    H. Zhang; Z. F. Chai; H. B. Sun; H. F. Xu

    2007-01-01

    To effectively extract organohalogens from human hair, two factors, the extracting time and hair length on the extraction\\u000a efficiency of organohalogens were studied by neutron activation analysis (NAA) and gas chromatograph-electron capture detector\\u000a (GC-ECD), respectively. Furthermore, the concentrations of extractable organohalogens (EOX) and extractable persistent organohalogens\\u000a (EPOX) in hair samples from angioma and control babies were also measured by the

  10. The determination of phosphorus by fast neutron activation analysis

    E-print Network

    To-On, Maen

    1964-01-01

    Activation IZST OF TABLES I Nuclear Reactions and Properties of Nuclei Formed by Bombarding phosphorus with Neutrons zz Determination of Phosphorus in Ammonium Di hydrogen Phosphate Samples XXX Determination of Phosphorus in Soluble Phos- phate Samples...'emoval of the silicon, The technique was tested on the following samples' ammonium dihydrogen phosphate, soluble phosphate~ lubrication oils, bio- logical materials, mixtures of ammonium dihydrogen phosphate~ silicon dioxide, fertilizer and phosphate rock samples...

  11. Neutron activation cross sections for zirconium isotopes

    Microsoft Academic Search

    V. Semkova; E. Bauge; A. J. M. Plompen; D. L. Smith

    2010-01-01

    New experimental cross sections are presented for Zr90(n,?)87mSr, Zr90(n,x)89mY, Zr90(n,p)90mY, Zr90(n,2n)89Zr, Zr90(n,2n)89mZr, Zr91(n,n?)87mSr, Zr91(n,x)90mY, Zr91(n,p)91mY, Zr92(n,x)91mY, Zr92(n,p)92Y, Zr94(n,?)91Sr, Zr94(n,x)93Y and Zr94(n,p)94Y reactions. These have been obtained with the activation technique using gamma-ray spectrometry and irradiations at the IRMM Van de Graaff laboratory. The new data were obtained in the energy range from 14 to 21 MeV. In nearly all cases

  12. Magnetar activity mediated by plastic deformations of neutron star crust

    NASA Astrophysics Data System (ADS)

    Lyutikov, Maxim

    2015-02-01

    We advance a `solar flare' model of magnetar activity, whereas a slow evolution of the magnetic field in the upper crust, driven by electron magnetohydrodynamic flows, twists the external magnetic flux tubes, producing persistent emission, bursts, and flares. At the same time, the neutron star crust plastically relieves the imposed magnetic field stress, limiting the strain ?t to values well below the critical strain ?crit of a brittle fracture, ?t ˜ 10-2?crit. Magnetar-like behaviour, occurring near the magnetic equator, takes place in all neutron stars, but to a different extent. The persistent luminosity is proportional to cubic power of the magnetic field (at a given age), and hence is hardly observable in most rotationally powered neutron stars. Giant flares can occur only if the magnetic field exceeds some threshold value, while smaller bursts and flares may take place in relatively small magnetic fields. Bursts and flares are magnetospheric reconnection events that launch Alfvén shocks which convert into high-frequency whistlers upon hitting the neutron star surface. The resulting whistler pulse induces a strain that increases with depth both due to the increasing electron density (and the resulting slowing of the waves), and due to the increasing coherence of a whistler pulse with depth. The whistler pulse is dissipated on a time-scale of approximately a day at shallow depths corresponding to ? ˜ 1010 g cm-3; this energy is detected as enhanced post-flare surface emission.

  13. Measurements and statistical model calculations of activation cross-sections for 26Mg(n,?) 23Ne reaction between 13.6 and 14.9 MeV neutron energies

    Microsoft Academic Search

    Adnan Elmal?; Iskender Atilla Reyhancan

    2008-01-01

    Activation cross-sections were measured at neutron energies from 13.6 to 14.9MeV for the reaction 26Mg(n,?)23Ne. The production of relatively short-lived activity and the spectra accumulation have been carried out by the cyclic activation method. Corrections were made for the effects of gamma-ray attenuation, random coincidence summing (pulse pile-up), dead time, and scattered low energy neutron contribution. Statistical model calculations for

  14. Determinations of the radii, redshifts, and atmospheric compositions of neutron stars from modeling their Chandra X-ray spectra

    NASA Astrophysics Data System (ADS)

    Stage, Michael D.

    2003-12-01

    Fitting the X-ray spectra of thermal radiation from neutron stars with realistic atmosphere models provides a way to place constraints on their radii, surface gravities and compositions, and to test general relativity in the strong field limit. Such determinations allow us to constrain the equation of state of nuclear matter. I present fits which constrain the radii and surface compositions of two neutron stars, using high quality Chandra X-ray Observatory observations of the point source in the Cassiopeia A supernova remnant (Cas A XPS), and the isolated neutron star RX J1856.5-3754. I apply models calculated with advanced versions of the ATM model atmosphere code developed by Madej and Joss for neutron- star atmospheres composed of hydrogen, hydrogen-helium, iron, or a silicon to iron mixture. The results, taken assuming a typical value of 1.4 solar masses, show that the X-ray emission is generated from hot spot regions of scale size ˜3 4 km, on stars of intrinsic radius 9 and 12.5 km. This implies a relatively stiff equation of state. For the Cas A XPS, I fit the most source photons to date with spectra extracted from three Chandra Advanced CCD Imaging Spectrometer observations (ObsIds 114, 1952, 1046), with a total effective exposure of approximately 110,000 seconds. With these data, I am able to show that atmosphere models fit significantly better than blackbody models, although a wide range of radii are permitted. I also present evidence of an absorption feature in the XPS spectrum caused by silicon present in the supernova remnant, and discuss efforts to fit CCD pileup of the spectrum. For the RX J1856.5-3754, I fit a 450,000 second Chandra Low Energy Transmission Grating/High Resolution Camera observation. My findings agree with previous results that a blackbody model provides the best fit, and reject hydrogen and iron atmospheres. While previous attempts to fit the spectrum with rotationally-blurred iron or solar abundance atmospheres have failed, I successfully fit the spectrum to a rotationally Doppler blurred silicon-ash model, a surface composition which might exist following a supernova. The fit implies a rotational period of approximately 2 ms. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

  15. A calculation of the neutron emission spectra and the neutron number produced by (p, n) reaction for some thick targets composed of heavy elements from 0.5 GeV to 3.0 GeV

    NASA Astrophysics Data System (ADS)

    Thu, Nguyen Thi Ai; Mong Giao, Nguyen

    2013-03-01

    The calculation of neutron multiplicity and its energy spectra in (p,n) reactions are very important and necessary for designing and manufacturing the target for an Accelerator Driven System (ADS). The neutron multiplicity in (p,n) reactions on different thin targets with different proton beam energies has been presented in the JENDL-HE library. However, the target used in the ADS must be thick so that the number of neutrons produced is as large as possible. For this reason, we can't directly use the results in the JENDL-HE library. In this paper, we calculate neutron emission spectra and multiplicity in (p,n) reactions for some thick target nuclei including Pb204, Pb206, Pb207, Pb208, W180, W182 W184 W186, U235, U238, Au197 with proton beam energies ranging from 0.5 GeV to 3.0 GeV.

  16. Neutron Time of Flight phonon spectra of Cu2O and Ag2O powders

    NASA Astrophysics Data System (ADS)

    Winn, Barry; Hagen, Mark; Shapiro, Steve

    2009-03-01

    Negative thermal expansion materials cuprite (Cu2O) and Ag2O share the same structure (space group Pn3m). Here, we report inelastic neutron time of flight measurements of room temperature powder samples of each system, using the Pharos chopper spectrometer at LANSCE, at up to 100 meV energy transfer. For Cu2O, high energy optical phonons are observed between 60 and 80 meV, while for Ag2O, these phonons are observed between 50 and 70 meV. Results are compared to previous work, and to recent neutron triple axis spectrometer results for Cu2O, and their relevance to negative thermal expansion is discussed.

  17. Inherent Protection of Plutonium by Doping Minor Actinide in Thermal Neutron Spectra

    Microsoft Academic Search

    Yoga PERYOGA; Hiroshi SAGARA; Masaki SAITO; Alexey EZOUBTCHENKO

    2005-01-01

    The present study focuses on the exploration of the effect of minor actinide (MA) addition into uranium oxide fuels of different enrichment (5% U and 20% U) as ways of increasing fraction of even-mass-number plutonium isotopes. Among plutonium isotopes, Pu, Pu and Pu have the characteristics of relatively high decay heat and spontaneous fission neutron rate that can improve proliferation-resistant

  18. Experimental and MCNP simulated gamma-ray spectra for the UNCOSS neutron-based explosive detector

    Microsoft Academic Search

    C. Eleon; B. Perot; C. Carasco; D. Sudac; J. Obhodas; V. Valkovic

    2011-01-01

    In the frame of the FP7 UNCOSS project (Underwater Coastal Sea Surveyor), whose aim is to develop a neutron-based explosive detection system to identify unexploded ordnance (UXO) lying on the sea bottom, the choice of the gamma-ray detector is essential to reach the optimal performances. This paper presents comparative tests between the two candidates: NaI(Tl) and LaBr3(Ce) detectors, in favour

  19. Measurement of action spectra of light-activated processes

    NASA Astrophysics Data System (ADS)

    Ross, Justin; Zvyagin, Andrei V.; Heckenberg, Norman R.; Upcroft, Jacqui; Upcroft, Peter; Rubinsztein-Dunlop, Halina H.

    2006-01-01

    We report on a new experimental technique suitable for measurement of light-activated processes, such as fluorophore transport. The usefulness of this technique is derived from its capacity to decouple the imaging and activation processes, allowing fluorescent imaging of fluorophore transport at a convenient activation wavelength. We demonstrate the efficiency of this new technique in determination of the action spectrum of the light mediated transport of rhodamine 123 into the parasitic protozoan Giardia duodenalis.

  20. Coincidence methods in low-level counting of neutron activated bioenvironmental samples

    SciTech Connect

    Landsberger, S.; Peshev, S.; Wu, D.; Biegalski, S. [Univ. of Illinois, Urbana, IL (United States)

    1994-12-31

    Although the counting techniques of instrumental neutron activation analysis (NAA) are well established in determining low level trace elements in bioenvironmental studies, little information has been reported in using more sophisticated coicidence methods to lower detection limits. Methods such epithermal NAA may reduce spectral backgrounds arising from activated products which exhibit 1/v cross sections. Radiochemical methods although very effective in determining many trace elements at the nanaogram and subnanogram level, are very time consuming, cannot be easily incorporated in large number of samples and sometimes are inappropriate when wanting to do multielemental analysis. Both Compton suppression and {gamma}-{gamma} coincidence methods are ideally suited in neutron activation studies, particularly in quantifying elements that are not usually determined. During the past several years our group has judiciously employed Compton suppression methods to determine several environmentally significant elements in airborne particulate matter, tobacco smoke, hazardous waste and botanical reference materials. Besides reducing the detection limits for copper, cadmium, silicon, nickel, etc. by suppressing the Compton continuum, spectra interferences are also significantly reduced particularly from radionuclides which emit coincident {gamma}-rays. This work will focus on the use of Comptons suppression methods and its value in environmental studies.

  1. Analysis of neutron diffraction spectra acquired [ital in situ] during stress-induced transformations in superelastic NiTi

    SciTech Connect

    Vaidyanathan, R. (Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)); Bourke, M.A. (LANSCE/MST, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)); Dunand, D.C. (Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States))

    1999-09-01

    Neutron diffraction spectra were obtained during various stages of a reversible stress-induced austenite to martensite phase transformation in superelastic NiTi. This was accomplished by neutron diffraction measurements on bulk polycrystalline NiTi samples simultaneously subjected to mechanical loading. Analysis of the data was carried out using individual lattice plane ([ital hkl]) reflections as well as by Rietveld refinement. In the Rietveld procedure, strains in austenite were described in terms of an isotropic ([ital hkl] independent) and an anisotropic ([ital hkl] dependent) component. At higher stresses, austenite lattice plane reflections exhibited nonlinear and dissimilar elastic responses which may be attributed to the transformation. The texture evolution is significant in both austenite and martensite phases during the transformation and two approaches were used to describe this evolving texture, i.e., an ellipsoidal model due to March[endash]Dollase and a generalized spherical-harmonic approach. The respective predictions of the phase fraction evolution as a function of applied stress were compared. A methodology is thus established to quantify the discrete phase strains, phase volume fractions, and texture during such transformations. [copyright] [ital 1999 American Institute of Physics.

  2. A study of aliphatic amino acids using simulated vibrational circular dichroism and Raman optical activity spectra*

    NASA Astrophysics Data System (ADS)

    Ganesan, Aravindhan; Brunger, Michael J.; Wang, Feng

    2013-11-01

    Vibrational optical activity (VOA) spectra, such as vibrational circular dichroism (VCD) and Raman optical activity (ROA) spectra, of aliphatic amino acids are simulated using density functional theory (DFT) methods in both gas phase (neutral form) and solution (zwitterionic form), together with their respective infrared (IR) and Raman spectra of the amino acids. The DFT models, which are validated by excellent agreements with the available experimental Raman and ROA spectra of alanine in solution, are employed to study other aliphatic amino acids. The inferred (IR) intensive region (below 2000 cm-1) reveals the signature of alkyl side chains, whereas the Raman intensive region (above 3000 cm-1) contains the information of the functional groups in the amino acids. Furthermore, the chiral carbons of the amino acids (except for glycine) dominate the VCD and ROA spectra in the gas phase, but the methyl group vibrations produce stronger VCD and ROA signals in solution. The C-H related asymmetric vibrations dominate the VOA spectra (i.e., VCD and ROA) > 3000 cm-1 reflecting the side chain structures of the amino acids. Finally the carboxyl and the C(2)H modes of aliphatic amino acids, together with the side chain vibrations, are very active in the VCD/IR and ROA/Raman spectra, which makes such the vibrational spectroscopic methods a very attractive means to study biomolecules.

  3. Optical vibronic absorption spectra in 14.8 MeV neutron damaged sapphire

    NASA Astrophysics Data System (ADS)

    Evans, B. D.; Stapelbroek, M.

    1980-02-01

    Preliminary observations of several anisotropic optical absorption bands are reported for high-purity sapphire following exposure to a pure 14.8 MeV neutron beam. These bands are compared with and found to be similar to those reported following fission-spectrum exposure, and are associated with lattice displacement damage. Two of these bands at 3.47 and 4.09 eV show similar sharpline features at low temperature; this ?200 cm -1 vibronic progression it tentatively associated with a local mode.

  4. Diffusive properties of water in Artemia cysts as determined from quasi-elastic neutron scattering spectra. [Artemia shrimp

    SciTech Connect

    Trantham, E.C.; Rorschach, H.E.; Clegg, J.S.; Hazlewood, C.F.; Nicklow, R.M.; Wakabayashi, N.

    1984-05-01

    Results have been obtained on the quasi-elastic spectra of neutrons scattered from pure water, 20% agarose gel (hydration four grams H/sub 2/O per gram of dry solid) and cysts of the brine shrimp Artemia for hydrations between 0.10 and 1.2 grams H/sub 2/O per gram of dry solids. The spectra were interpreted using a two-component model that included contributions from the covalently bonded protons and the hydration water, and a mobile water fraction. The mobile fraction was described by a jump-diffusion correlation function for the translation motion and a simple diffusive orientational correlation function. The results for the line widths ..gamma..(Q/sup 2/) for pure water were in good agreement with previous measurements. The agarose results were consistent with NMR measurements that show a slightly reduced translational diffusion for the mobile water fraction. The Artemia results show that the translational diffusion coefficient of the mobile water fraction was greatly reduced from that of pure water. The line width was determined mainly by the rotational motion, which was also substantially reduced from the pure water value as determined from dielectric relaxation studies. The translational and rotational diffusion parameters were consistent with the NMR measurements of diffusion and relaxation. Values for the hydration fraction and the mean square thermal displacement as determined from the Q-dependence of line areas were also obtained.

  5. Calculation of effective dose from measurements of secondary neutron spectra and scattered photon dose from dynamic MLC IMRT for 6 MV, 15 MV, and 18 MV beam energies

    Microsoft Academic Search

    Rebecca M. Howell; Nolan E. Hertel; Wang Zhonglu; Jesson Hutchinson; Gary D. Fullerton

    2006-01-01

    Effective doses were calculated from the delivery of 6 MV, 15 MV, and 18 MV conventional and intensity-modulated radiation therapy (IMRT) prostate treatment plans. ICRP-60 tissue weighting factors were used for the calculations. Photon doses were measured in phantom for all beam energies. Neutron spectra were measured for 15 MV and 18 MV and ICRP-74 quality conversion factors used to

  6. NEUTRON ACTIVATION ANALYSIS APPLICATIONS AT THE SAVANNAH RIVER SITE USING AN ISOTOPIC NEUTRON SOURCE

    SciTech Connect

    Diprete, D; C Diprete, C; Raymond Sigg, R

    2006-08-14

    NAA using {sup 252}Cf is used to address important areas of applied interest at SRS. Sensitivity needs for many of the applications are not severe; analyses are accomplished using a 21 mg {sup 252}Cf NAA facility. Because NAA allows analysis of bulk samples, it offers strong advantages for samples in difficult-to-digest matrices when its sensitivity is sufficient. Following radiochemical separation with stable carrier addition, chemical yields for a number methods are determined by neutron activation of the stable carrier. In some of the cases where no suitable stable carriers exist, the source has been used to generate radioactive tracers to yield separations.

  7. Monte Carlo Calculation of Thermal Neutron Inelastic Scattering Cross Section Uncertainties by Sampling Perturbed Phonon Spectra

    NASA Astrophysics Data System (ADS)

    Holmes, Jesse Curtis

    Nuclear data libraries provide fundamental reaction information required by nuclear system simulation codes. The inclusion of data covariances in these libraries allows the user to assess uncertainties in system response parameters as a function of uncertainties in the nuclear data. Formats and procedures are currently established for representing covariances for various types of reaction data in ENDF libraries. This covariance data is typically generated utilizing experimental measurements and empirical models, consistent with the method of parent data production. However, ENDF File 7 thermal neutron scattering library data is, by convention, produced theoretically through fundamental scattering physics model calculations. Currently, there is no published covariance data for ENDF File 7 thermal libraries. Furthermore, no accepted methodology exists for quantifying or representing uncertainty information associated with this thermal library data. The quality of thermal neutron inelastic scattering cross section data can be of high importance in reactor analysis and criticality safety applications. These cross sections depend on the material's structure and dynamics. The double-differential scattering law, S(alpha, beta), tabulated in ENDF File 7 libraries contains this information. For crystalline solids, S(alpha, beta) is primarily a function of the material's phonon density of states (DOS). Published ENDF File 7 libraries are commonly produced by calculation and processing codes, such as the LEAPR module of NJOY, which utilize the phonon DOS as the fundamental input for inelastic scattering calculations to directly output an S(alpha, beta) matrix. To determine covariances for the S(alpha, beta) data generated by this process, information about uncertainties in the DOS is required. The phonon DOS may be viewed as a probability density function of atomic vibrational energy states that exist in a material. Probable variation in the shape of this spectrum may be established that depends on uncertainties in the physics models and methodology employed to produce the DOS. Through Monte Carlo sampling of perturbations from the reference phonon spectrum, an S(alpha, beta) covariance matrix may be generated. In this work, density functional theory and lattice dynamics in the harmonic approximation are used to calculate the phonon DOS for hexagonal crystalline graphite. This form of graphite is used as an example material for the purpose of demonstrating procedures for analyzing, calculating and processing thermal neutron inelastic scattering uncertainty information. Several sources of uncertainty in thermal neutron inelastic scattering calculations are examined, including sources which cannot be directly characterized through a description of the phonon DOS uncertainty, and their impacts are evaluated. Covariances for hexagonal crystalline graphite S(alpha, beta) data are quantified by coupling the standard methodology of LEAPR with a Monte Carlo sampling process. The mechanics of efficiently representing and processing this covariance information is also examined. Finally, with appropriate sensitivity information, it is shown that an S(alpha, beta) covariance matrix can be propagated to generate covariance data for integrated cross sections, secondary energy distributions, and coupled energy-angle distributions. This approach enables a complete description of thermal neutron inelastic scattering cross section uncertainties which may be employed to improve the simulation of nuclear systems.

  8. Coincidence Prompt Gamma-Ray Neutron Activation Analysis

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

    Clifford, E. T. H.; McFee, J. E.; Ing, H.; Andrews, H. R.; Tennant, D.; Harper, E.; Faust, A. A.

    2007-08-01

    The Canadian Department of National Defence has developed a teleoperated, vehicle-mounted, multi-sensor system to detect anti-tank landmines on roads and tracks in peacekeeping operations. A key part of the system is a thermal neutron activation (TNA) sensor which is placed above a suspect location to within a 30 cm radius and confirms the presence of explosives via detection of the 10.835 MeV gamma ray associated with thermal neutron capture on 14N. The TNA uses a 100 ?g252Cf neutron source surrounded by four 7.62 cm×7.62 cm NaI(Tl) detectors. The system, consisting of the TNA sensor head, including source, detectors and shielding, the high-rate, fast pulse processing electronics and the data processing methodology are described. Results of experiments to characterize detection performance are also described. The experiments have shown that anti-tank mines buried 10 cm or less can be detected in roughly a minute or less, but deeper mines and mines significantly displaced horizontally take considerably longer time. Mines as deep as 30 cm can be detected for long count times (1000 s). Four TNA detectors are now in service with the Canadian Forces as part of the four multi-sensor systems, making it the first militarily fielded TNA sensor and the first militarily fielded confirmation sensor for landmines. The ability to function well in adverse climatic conditions has been demonstrated, both in trials and operations.

  10. Diagnosing suprathermal ion populations in Z-pinch plasmas using fusion neutron spectra

    NASA Astrophysics Data System (ADS)

    Knapp, P. F.; Sinars, D. B.; Hahn, K. D.

    2013-06-01

    The existence of suprathermal ion populations gives rise to significant broadening of and modifications to the fusion neutron spectrum. We show that when this population takes the form of a power-law at high energies, specific changes occur to the spectrum which are diagnosable. In particular, the usual Gaussian spectral shape produced by a thermal plasma is replaced by a Lorentz-like spectrum with broad wings extending far from the spectral peak. Additionally, it is found that the full width at half maximum of the spectrum depends on both the ion temperature and the power-law exponent. This causes the use of the spectral width for determination of the ion temperature to be unreliable. We show that these changes are distinguishable from other broadening mechanisms, such as temporal and motional broadening, and that detailed fitting of the spectral shape is a promising method for extracting information about the state of the ions.

  11. Diagnosing suprathermal ion populations in Z-pinch plasmas using fusion neutron spectra

    SciTech Connect

    Knapp, P. F.; Sinars, D. B.; Hahn, K. D. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2013-06-15

    The existence of suprathermal ion populations gives rise to significant broadening of and modifications to the fusion neutron spectrum. We show that when this population takes the form of a power-law at high energies, specific changes occur to the spectrum which are diagnosable. In particular, the usual Gaussian spectral shape produced by a thermal plasma is replaced by a Lorentz-like spectrum with broad wings extending far from the spectral peak. Additionally, it is found that the full width at half maximum of the spectrum depends on both the ion temperature and the power-law exponent. This causes the use of the spectral width for determination of the ion temperature to be unreliable. We show that these changes are distinguishable from other broadening mechanisms, such as temporal and motional broadening, and that detailed fitting of the spectral shape is a promising method for extracting information about the state of the ions.

  12. Enzyme hydration, activity and flexibility : A neutron scattering approach

    SciTech Connect

    Kurkal-Siebert, V [University of Heidelberg; Finney, J.L. [University College, London; Daniel, R. M. [University of Waikato, New Zealand; Smith, Jeremy C [ORNL

    2006-01-01

    Recent measurements have demonstrated enzyme activity at hydrations as low as 3%. The question of whether the hydration-induced enzyme flexibility is important for activity is addressed by performing picosecond dynamic neutron scattering experiments on pig liver esterase powders at various temperatures as well as solutions. At all temperatures and hydrations investigated here, significant quasielastic scattering intensity is found in the protein, indicating the presence of anharmonic, diffusive motion. As the hydration increases a temperature-dependent dynamical transition appears and strengthens involving additional diffusive motion. At low temperature, increasing hydration resulted in lower flexibility of the enzyme. At higher temperatures, systems containing sufficient number of water molecules interacting with the protein exhibit increased flexibility. The implication of these results is that, although the additional hydration-induced diffusive motion and flexibility at high temperatures in the enzyme detected here may be related to increased activity, they are not required for the enzyme to function.

  13. Activation of cobalt by neutrons from the Hiroshima bomb

    SciTech Connect

    Kerr, G.D.; Dyer, F.F.; Emery, J.F.; Pace, J.V. III (Oak Ridge National Lab., TN (USA)); Brodzinski, R.L. (Pacific Northwest Lab., Richland, WA (USA)); Marcum, J. (R and D Associates, Marina del Rey, CA (USA))

    1990-02-01

    A study has been completed of cobalt activation in samples from two new locations in Hiroshima. The samples consisted of a piece of steel from a bridge located at a distance of about 1300 m from the hypocenter and pieces of both steel and concrete from a building located at approximately 700 m. The concrete was analyzed to obtain information needed to calculate the cobalt activation in the two steel samples. Close agreement was found between calculated and measured values for cobalt activation of the steel sample from the building at 700 m. It was found, however, that the measured values for the bridge sample at 1300 m were approximately twice the calculated values. Thus, the new results confirm the existence of a systematic error in the transport calculations for neutrons from the Hiroshima bomb. 52 refs., 32 figs., 16 tabs.

  14. Vanadium in human serum, as determined by neutron activation analysis

    SciTech Connect

    Simonoff, M.; Llabador, Y.; Peers, A.M.; Simonoff, G.N.

    1984-10-01

    Vanadium concentrations have been measured in the serum of 23 healthy subjects by neutron activation analysis, with post-irradiation chemical separation. The values obtained fall in a fairly narrow range (260-1300 ng/L, mean 670 ng/L), which suggests a physiological role for this element. The authors checked the method by analysis of standard (U.S. National Bureau of Standards) water samples and serum samples supplemented with /sup 48/V, and found excellent agreement with expected results in both cases. They consider the reported results for human serum to be more reliable than those obtained by atomic absorption spectroscopy.

  15. Gold analyses by neutron activation from SRL NURE samples

    SciTech Connect

    Fay, W M; Cook, J R

    1982-04-01

    This data report presents 3889 gold concentrations of stream sediments collected and analyzed by the Savannah River Laboratory as part of the NURE program. Gold concentrations were determined by neutron activation of 1.5 grams of -100 mesh sediment with a detection limit of about 0.01 ppM. Samples in which gold was not detected are not reported. The report consists of tabulated data, a brief description of sample collection and analytical methods, and a discussion of some possible factors affecting the data.

  16. Intercomparison Between Neutron Activation Analysis Laboratories for Trace Elements Determination in Lacustrine Sediments

    Microsoft Academic Search

    Lucretia C. Dinescu; Otilia A. Culicov; Octavian G. Duliu; Marina V. Frontasyeva; Cristiana D. Oprea

    2003-01-01

    An intercomparison concerning the concentrations of 23 major and trace elements in recent lacustrine sediments, as determined by Instrumental Neutron Activation Analysis, has been performed by using epithermal neutrons at the Joint institute of Nuclear Research, Dubna, (Russia) and thermal neutrons at the National Institute for Physics and Nuclear Engineering, Bucharest, (Romania). Sc, La, Tb, Yb, Th, Na, Rb, Cs,

  17. The THz fingerprint spectra of the active ingredients of a TCM medicine: Herba Ephedrae

    NASA Astrophysics Data System (ADS)

    Ma, Shihua; Liu, Guifeng; Zhang, Peng; Song, Xiyu; Ji, Te; Wang, Wenfeng

    2008-12-01

    In this paper, THz-TDS has been used to measure the spectral properties of two active ingredients of Herba Ephedrae: ephedrine and pseudoephedrine, which exist in hydrochloride salts. The THz spectra of the sole-ingredient, twoingredient and three-ingredient compounds are studied. We obtained the finger-print spectra of the net active ingredients of the medicine, and also measured the mixtures of by two or three active ingredients at the different ratios. At the same time, theoretical analysis and quantitative analysis is applied to foretell the different THz spectra, identify the ingredients and infer the contents of principal components in samples. The THz spectroscopy is a potential and promising technique in evaluating and inspecting the quality of the drugs in the TCM field.

  18. Magnetic spectra in the tridiminished-icosahedron {Fe9} nanocluster by inelastic neutron scattering

    SciTech Connect

    Vaknin, David [Ames Laboratory; Demmel, Franz [Rutherford Appleton Laboratory

    2014-05-01

    Inelastic neutron scattering (INS) experiments under applied magnetic field at low temperatures show detailed low-lying magnetic excitations in the so-called tridiminshed iron icosahedron magnetic molecule. The magnetic molecule consists of nine iron Fe3+ (s=5/2) and three phosphorous atoms that are situated on the 12 vertices of a nearly perfect icosahedron. The three phosphorous atoms form a plane that separates the iron cluster into two weakly coupled three- and six-ion fragments, {Fe3} and {Fe6}, respectively. The magnetic field INS results exhibit an S=1/2 ground state expected from a perfect equilateral triangle of the {Fe3} triad with a powder averaged g value =2.00. Two sets of triplet excitations whose temperature and magnetic field dependence indicate an S=0 ground state with two nondegenerate S=1 states are attributed to the {Fe6} fragment. The splitting may result from a finite coupling between the two fragments, single-ion anisotropy, antisymmetric exchange couplings, or from magnetic frustration of its triangular building blocks.

  19. Symmetry adapted cluster-configuration interaction calculation of the photoelectron spectra of famous biological active steroids

    NASA Astrophysics Data System (ADS)

    Abyar, Fatemeh; Farrokhpour, Hossein

    2014-11-01

    The photoelectron spectra of some famous steroids, important in biology, were calculated in the gas phase. The selected steroids were 5?-androstane-3,11,17-trione, 4-androstane-3,11,17-trione, cortisol, cortisone, corticosterone, dexamethasone, estradiol and cholesterol. The calculations were performed employing symmetry-adapted cluster/configuration interaction (SAC-CI) method using the 6-311++G(2df,pd) basis set. The population ratios of conformers of each steroid were calculated and used for simulating the photoelectron spectrum of steroid. It was found that more than one conformer contribute to the photoelectron spectra of some steroids. To confirm the calculated photoelectron spectra, they compared with their corresponding experimental spectra. There were no experimental gas phase Hesbnd I photoelectron spectra for some of the steroids of this work in the literature and their calculated spectra can show a part of intrinsic characteristics of this molecules in the gas phase. The canonical molecular orbitals involved in the ionization of each steroid were calculated at the HF/6-311++g(d,p) level of theory. The spectral bands of each steroid were assigned by natural bonding orbital (NBO) calculations. Knowing the electronic structures of steroids helps us to understand their biological activities and find which sites of steroid become active when a modification is performing under a biological pathway.

  20. Procedures for multielement analysis using high-flux fast-neutron activation. [14-MeV neutrons

    SciTech Connect

    Williams, R.E.; Hopke, P.K.; Meyer, R.A.

    1981-06-01

    Improvements have been made in the rabbit system used for multi-element fast-neutron activation analysis at the Lawrence Livermore National Laboratory Rotating Target Neutron Source, RTNS-I. Procedures have been developed for the analysis of 20 to 25 elements in samples with an inorganic matrix and 10 to 15 elements in biological samples, without the need for prohibitively expensive, long irradiations. Results are presented for the analysis of fly ash, orchard leaves, and bovine liver.

  1. Determination of 30 elements in coal and fly ash by thermal and epithermal neutron-activation analysis

    USGS Publications Warehouse

    Rowe, J.J.; Steinnes, E.

    1977-01-01

    Thirty elements are determined in coal and fly ash by instrumental neutron-activation analysis using both thermal and epithermal irradiation. Gamma-ray spectra were recorded 7 and 20 days after the irradiations. The procedure is applicable to the routine analysis of coals and fly ash. Epithermal irradiation was found preferable for the determination of Ni, Zn, As, Se, Br, Rb, Sr, Mo, Sb, Cs, Ba, Sm, Tb, Hf, Ta, W, Th and U, whereas thermal irradiation was best for Sc, Cr, Fe, Co, La, Ce, Nd, Eu, Yb and Lu. Results for SRM 1632 (coal) and SRM 1633 (fly ash) agree with those of other investigators. ?? 1977.

  2. THERMAL NEUTRON ACTIVATION CROSS-SECTIONS OF SOME NUCLIDES USED IN ACTIVATION MEASUREMENTS

    Microsoft Academic Search

    Jozefowicz

    1963-01-01

    The method of absolute beta activity measurements in liquid ; scintillators was used to measure the thermal neutron activation cross-sections ; of phosphorus, iodine, and indium in relation to sodium and manganese. The ; following results were obtained: olytic C and \\/sub op\\/= 0.172 surface proces ; 0.008 b; olytic C and \\/sub oj\\/ = 5.8 surfa00.2 b; olytic C

  3. Epithermal Neutron Activation Analysis of the Asian Herbal Plants

    NASA Astrophysics Data System (ADS)

    Baljinnyam, N.; Jugder, B.; Norov, N.; Frontasyeva, M. V.; Ostrovnaya, T. M.; Pavlov, S. S.

    2011-06-01

    Asian medicinal herbs Chrysanthemum (Spiraea aquilegifolia Pall.) and Red Sandalwood (Pterocarpus Santalinus) are widely used in folk and Ayurvedic medicine for healing and preventing some diseases. The modern medical science has proved that the Chrysanthemum (Spiraea aquilegifolia Pall.) possesses the following functions: reducing blood press, dispelling cancer cell, coronary artery's expanding and bacteriostating and Red Sandalwood (Pterocarpus Santalinus) is recommended against headache, toothache, skin diseases, vomiting and sometimes it is taken for treatment of diabetes. Species of Chrysanthemums were collected in the north-eastern and central Mongolia, and the Red Sandalwood powder was imported from India. Samples of Chrysanthemums (branches, flowers and leaves) (0.5 g) and red sandalwood powder (0.5 g) were subjected to the multi-element instrumental neutron activation analysis using epithermal neutrons (ENAA) at the IBR-2 reactor, Frank Laboratory of Neutron Physics (FLNP) JINR, Dubna. A total of 41 elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Sr, Zr, Mo, Cd, Cs, Ba, La, Hf, Ta, W, Sb, Au, Hg, Ce, Nd, Sm, Eu, Tb, Dy, Yb, Th, U, Lu) were determined. For the first time such a large group of elements was determined in the herbal plants used in Mongolia. The quality control of the analytical results was provided by using certified reference material Bowen Cabbage. The results obtained are compared to the "Reference plant» data (B. Markert, 1992) and interpreted in terms of excess of such elements as Se, Cr, Ca, Fe, Ni, Mo, and rare earth elements.

  4. THE THERMAL NEUTRON ACTIVATION CROSS SECTION OF ¹°⁵Ru

    Microsoft Academic Search

    1961-01-01

    To calculate the thermal neutron activation cross section of Ru¹°⁵; , the enriched Ru¹°⁴ was exposed to a thermal neutron flux of 1.2 x 10\\/sup ; 14\\/ neutrons cm-\\/sup 2 s-1\\/. After the decay of the 40-day activity of Ru\\/sup ; 103\\/, the silver impurity was removed and the contributions from cobalt and ; europium impurities were subtracted. The gamma

  5. Preparation of neutron-activated xenon for liquid xenon detector calibration

    Microsoft Academic Search

    K. Ni; R. Hasty; T. M. Wongjirad; L. Kastens; A. Manzur; D. N. McKinsey

    2007-01-01

    We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a 5-day activation of natural xenon gas with a 252Cf (4×105n\\/s) source, the activities of two gamma ray lines

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

    NASA Astrophysics Data System (ADS)

    Lewis, Jason M.

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

  7. Tables for simplifying calculations of activities produced by thermal neutrons

    USGS Publications Warehouse

    Senftle, F.E.; Champion, W.R.

    1954-01-01

    The method of calculation described is useful for the types of work of which examples are given. It is also useful in making rapid comparison of the activities that might be expected from several different elements. For instance, suppose it is desired to know which of the three elements, cobalt, nickel, or vanadium is, under similar conditions, activated to the greatest extent by thermal neutrons. If reference is made to a cross-section table only, the values may be misleading unless properly interpreted by a suitable comparison of half-lives and abundances. In this table all the variables have been combined and the desired information can be obtained directly from the values of A 3??, the activity produced per gram per second of irradiation, under the stated conditions. Hence, it is easily seen that, under similar circumstances of irradiation, vanadium is most easily activated even though the cross section of one of the cobalt isotopes is nearly five times that of vanadium and the cross section of one of the nickel isotopes is three times that of vanadium. ?? 1954 Societa?? Italiana di Fisica.

  8. Use of coincident and non-coincident gamma-rays in Compton suppression neutron activation analysis

    Microsoft Academic Search

    S. Landsberger; S. R. Biegalski; D. J. O’Kelly; M. S. Basunia

    2005-01-01

    Summary  In the last decade Compton suppressed neutron activation analysis has had increasing popularity as a powerful method to significantly lower backgrounds and reduce overlapping peaks caused by spectral or nuclear interferences. We give a detailed descriptive evaluation of the unique features of this technique and its usefulness in many areas of research employing non-destructive neutron activation analysis.

  9. Methods and procedures for evaluation of neutron-induced activation cross sections

    Microsoft Academic Search

    1981-01-01

    One cannot expect measurements alone to supply all of the neutron-induced activation cross-section data required by the fission reactor, fusion reactor, and nuclear weapons development communities, given the wide ranges of incident neutron energies, the great variety of possible reaction types leading to activation, and targets both stable and unstable. Therefore, the evaluator must look to nuclear model calculations and

  10. COLLISIONAL ACTIVATION MASS SPECTRA OF M-. IONS OF AZO DYES CONTAINING 2-NAPHTHOL

    EPA Science Inventory

    Collisionally activated decomposition mass spectra of M- ions of azo dyes are presented. he compounds are of general structure Ar(l)-N=N-Ar(2), where Ar(l) is substituted phenyl and Ar(2) is 2-naphthol. Characteristic fragment ions observed include m/z 157, which corresponds to t...

  11. Assessing Neutron Generator Output Using Delayed Activation of Silicon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Deuterium-tritium (D-T) neutron generators are used for elemental composition analysis and medical applications. Often composition is determined by examining elemental ratios in which the knowledge of the neutron flux is unnecessary. However, the absolute value of the neutron flux is required when t...

  12. Calculation of effective dose from measurements of secondary neutron spectra and scattered photon dose from dynamic MLC IMRT for 6 MV, 15 MV, and 18 MV beam energies

    SciTech Connect

    Howell, Rebecca M.; Hertel, Nolan E.; Wang Zhonglu; Hutchinson, Jesson; Fullerton, Gary D. [Emory University School of Medicine, Department of Radiation Oncology, 1365 Clifton Road AT200, Atlanta, Georgia 30322 (United States); Georgia Institute of Technology, 900 Atlantic Drive, Atlanta, Georgia 30332 (United States); Univ. Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, Texas 78229 (United States)

    2006-02-15

    Effective doses were calculated from the delivery of 6 MV, 15 MV, and 18 MV conventional and intensity-modulated radiation therapy (IMRT) prostate treatment plans. ICRP-60 tissue weighting factors were used for the calculations. Photon doses were measured in phantom for all beam energies. Neutron spectra were measured for 15 MV and 18 MV and ICRP-74 quality conversion factors used to calculate ambient dose equivalents. The ambient dose equivalents were corrected for each tissue using neutron depth dose data from the literature. The depth corrected neutron doses were then used as a measure of the neutron component of the ICRP protection quantity, organ equivalent dose. IMRT resulted in an increased photon dose to many organs. However, the IMRT treatments resulted in an overall decrease in effective dose compared to conventional radiotherapy. This decrease correlates to the ability of an intensity-modulated field to minimize dose to critical normal structures in close proximity to the treatment volume. In a comparison of the three beam energies used for the IMRT treatments, 6 MV resulted in the lowest effective dose, while 18 MV resulted in the highest effective dose. This is attributed to the large neutron contribution for 18 MV compared to no neutron contribution for 6 MV.

  13. Clinical applications of in vivo neutron-activation analysis

    SciTech Connect

    Cohn, S.H.

    1982-01-01

    In vivo neutron activation has opened a new era of both clinical diagnosis and therapy evaluation, and investigation into and modelling of body composition. The techniques are new, but it is already clear that considerable strides can be made in increasing accuracy and precision, increasing the number of elements susceptible to measurement, enhancing uniformity, and reducing the dose required for the measurement. The work presently underway will yield significant data on a variety of environmental contaminants such as Cd. Compositional studies are determining the level of vital constituents such as nitrogen and potassium in both normal subjects and in patients with a variety of metabolic disorders. Therapeutic programs can be assessed while in progress.

  14. Neutron activation analysis of sea-, lake-, and evaporated salt

    NASA Astrophysics Data System (ADS)

    Steinhauser, G.; Sterba, J. H.; Poljanc, K.; Bichler, M.; Buchtela, K.

    2006-01-01

    Salt is essential for human nutrition. Recently, it has become popular in Europe to rather use exotic sea salt or lake salt instead of purified evaporated salt, because of an alleged higher content of trace elements. In this study the content of trace elements and their bioavailability of 19 samples of different types of salt and 1 sample of brine purification sludge were investigated using instrumental neutron activation analysis. In general, sea-, lake-, and evaporated salt are quite pure. Trace elements determined in salt were Al, Br, Co, Cr, Cs, Fe, Rb, Sc, Sr, and Zn; some of them only in individual cases. It was found that, in general, the content of trace elements in sea- or lake salt was higher than in purified salt. Nevertheless, the use of sea- or lake salt does not contribute significantly to the human needs of essential trace elements, because their concentration in salt is too low or their compounds are not bioavailable.

  15. In-vivo neutron activation analysis: principles and clinical applications

    SciTech Connect

    Cohn, S.H.

    1982-01-01

    In vivo neutron activation has opened a new era of both clinical diagnosis and therapy evaluation, and investigation into and modelling of body composition. The techniques are new, but it is already clear that considerable strides can be made in increasing accuracy and precision, increasing the number of elements susceptible to measurement, enhancing uniformity, and reducing the dose required for the measurement. The work presently underway will yield significant data on a variety of environmental contaminants such as Cd. Compositional studies are determining the level of vital constituents such as nitrogen and potassium in both normal subjects and in patients with a variety of metabolic disorders. Therapeutic programs can be assessed while in progress. It seems likely that by the end of this century there will have been significant progress with this research tool, and exciting insights obtained into the nature and dynamics of human body composition.

  16. Measurements of the neutron activation cross sections for Bi and Co at 386 MeV.

    PubMed

    Yashima, H; Sekimoto, S; Ninomiya, K; Kasamatsu, Y; Shima, T; Takahashi, N; Shinohara, A; Matsumura, H; Satoh, D; Iwamoto, Y; Hagiwara, M; Nishiizumi, K; Caffee, M W; Shibata, S

    2014-10-01

    Neutron activation cross sections for Bi and Co at 386 MeV were measured by activation method. A quasi-monoenergetic neutron beam was produced using the (7)Li(p,n) reaction. The energy spectrum of these neutrons has a high-energy peak (386 MeV) and a low-energy tail. Two neutron beams, 0° and 25° from the proton beam axis, were used for sample irradiation, enabling a correction for the contribution of the low-energy neutrons. The neutron-induced activation cross sections were estimated by subtracting the reaction rates of irradiated samples for 25° irradiation from those of 0° irradiation. The measured cross sections were compared with the findings of other studies, evaluated in relation to nuclear data files and the calculated data by Particle and Heavy Ion Transport code System code. PMID:24368868

  17. The study of neutron activation yields in spallation reaction of 400 MeV/u carbon on a thick lead target

    E-print Network

    F. Ma; H. L. Ge; X. Y. Zhang; H. B. Zhang; Y. Q. Ju; L. Chen; L. Yang; F. Fu; Y. L. Zhang; J. Y. LI; T. J. Liang; B. Zhou; S. L. Wang; J. Y. Li; J. K. Xu; X. G. Leir; Z. Qin; L. Gu; G. M. Jin

    2013-09-03

    The spallation-neutron yield was studied experimentally by bombarding a thick lead target with 400 MeV/u carbon beam. The data were obtained with the activation analysis method using foils of Au, Mn, Al, Fe and In. The yields of produced isotopes were deduced by analyzing the measured {\\gamma} spectra of irradiated foils. According to the isotopes yields, the spatial and energy distributions of the neutron field were discussed. The experimental results were compared with Monte Carlo simulations performed by the GEANT4 + FLUKA code.

  18. The investigation of spices by use of instrumental neutron activation analysis

    E-print Network

    Wise, Jatara Rob

    2008-10-10

    contaminants. For this research, instrumental neutron-activation analysis (INAA) was used to determine the activities of U-235 fission products in common spices. Using this information, the concentrations of natural uranium in these spices and the doses...

  19. The investigation of spices by use of instrumental neutron activation analysis 

    E-print Network

    Wise, Jatara Rob

    2008-10-10

    contaminants. For this research, instrumental neutron-activation analysis (INAA) was used to determine the activities of U-235 fission products in common spices. Using this information, the concentrations of natural uranium in these spices and the doses...

  20. The role of neutron activation analysis in nutritional biomonitoring programs

    SciTech Connect

    Iyengar, V.

    1988-01-01

    Nutritional biomonitoring is a multidisciplinary task and an integral part of a more general bioenvironmental surveillance. In its comprehensive form, it is a combination of biological, environmental, and nutrient monitoring activities. Nutrient monitoring evaluates the input of essential nutrients required to maintain vital bodily functions; this includes vigilance over extreme fluctuations of nutrient intake in relation to the recommended dietary allowances and estimated safe and adequate daily dietary intakes and adherence to the goals of provisional tolerance limits. Environmental monitoring assesses the external human exposure via ambient pathways, namely, air, water, soil, food, etc. Biological monitoring quantifies a toxic agent and its metabolites in representative biologic specimens of an exposed organ to identify health effects. In practice, coordinating all three components of a nutritional biomonitoring program is complex, expensive, and tedious. Experience gained from the US National Health and Nutrition Examination Surveys demonstrates the problems involved. By far the most critical challenge faced here is the question of analytical quality control, particularly when trace element determinations are involved. Yet, measures to ensure reliability of analytical data are mandatory, and there are no short-cuts to this requirement. The purpose of this presentation is to elucidate the potential of neutron activation analysis (NAA) in nutritional biomonitoring activities.

  1. Health physics aspects of neutron activated components in a linear accelerator.

    PubMed

    Guo, Shuntong; Ziemer, Paul L

    2004-05-01

    The purpose of this study was to investigate the residual radioactivity in the therapy accessories of a medical x ray linear accelerator. The residual radioactivity mainly originated from nuclear activation reactions by neutrons, which are present as a contamination radiation in the x-ray beam. The radiation used in this study was the 25 MV x-ray beam produced by a CGR Saturne III linear accelerator. The five treatment aids include four wedges of various angles and one cerrobend block. The decrease in dose rates with time was followed for 60 min for each of the five treatment aids immediately after 999 monitor units of irradiation. The integral doses from the surface of each of four activated therapy accessories following three different radiation doses were measured by using thermoluminescent dosimeters (CaF2). In the TLD measurement, polyethylene filters were used to differentiate beta or beta particles from the mixed decay radiation. A high-purity germanium detection system was utilized to collect and to analyze the gamma spectra from the activated therapy accessories. The residual radioisotopes found in the 15 degree wedge and 30 degree wedge included V, Cr, Cr, Mn, Fe, Co, and Ni. In the 45 degree and 60 degree wedges, the radionuclides identified were Co, Ni, Cu, and W. The principal nuclides identified in the irradiated cerrobend block were In, Sn, Cd, Pb. The corresponding nuclear reactions from which the residual radionuclides produced were confirmed by consulting the current literature. PMID:15069298

  2. Neutron-capture prompt. gamma. -ray activation analysis for multielement determination in complex samples

    Microsoft Academic Search

    M. P. Failey; D. L. Anderson; W. H. Zoller; G. E. Gordon; R. M. Lindstrom

    1979-01-01

    Gamma-ray spectra were taken up to 11 MeV from a wide range of samples and elemental standards while under neutron irradiation to determine the elements whose prompt ..gamma.. rays are observable and can be used for analytical measurement. Up to 17 elements from among the set H, B, C, N, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti,

  3. Local Luminous Infrared Galaxies. II. Active Galactic Nucleus Activity from Spitzer/Infrared Spectrograph Spectra

    NASA Astrophysics Data System (ADS)

    Alonso-Herrero, Almudena; Pereira-Santaella, Miguel; Rieke, George H.; Rigopoulou, Dimitra

    2012-01-01

    We quantify the active galactic nucleus (AGN) contribution to the mid-infrared (mid-IR) and the total infrared (IR, 8-1000 ?m) emission in a complete volume-limited sample of 53 local luminous infrared galaxies (LIRGs, L IR = 1011-1012 L ?). We decompose the Spitzer Infrared Spectrograph low-resolution 5-38 ?m spectra of the LIRGs into AGN and starburst components using clumpy torus models and star-forming galaxy templates, respectively. We find that 50% (25/50) of local LIRGs have an AGN component detected with this method. There is good agreement between these AGN detections through mid-IR spectral decomposition and other AGN indicators, such as the optical spectral class, mid-IR spectral features, and X-ray properties. Taking all the AGN indicators together, the AGN detection rate in the individual nuclei of LIRGs is ~62%. The derived AGN bolometric luminosities are in the range L bol(AGN) = (0.4-50) × 1043 erg s-1. The AGN bolometric contribution to the IR luminosities of the galaxies is generally small, with 70% of LIRGs having L bol[AGN]/L IR <= 0.05. Only ~= 8% of local LIRGs have a significant AGN bolometric contribution L bol[AGN]/L IR > 0.25. From the comparison of our results with literature results of ultraluminous infrared galaxies (L IR = 1012-1013 L ?), we confirm that in the local universe the AGN bolometric contribution to the IR luminosity increases with the IR luminosity of the galaxy/system. If we add up the AGN bolometric luminosities we find that AGNs only account for 5%^{+8%}_{-3%} of the total IR luminosity produced by local LIRGs (with and without AGN detections). This proves that the bulk of the IR luminosity of local LIRGs is due to star formation activity. Taking the newly determined IR luminosity density of LIRGs in the local universe, we then estimate an AGN IR luminosity density of ?AGN IR = 3 × 105 L ? Mpc-3 in LIRGs. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407.

  4. LOCAL LUMINOUS INFRARED GALAXIES. II. ACTIVE GALACTIC NUCLEUS ACTIVITY FROM SPITZER/INFRARED SPECTROGRAPH SPECTRA

    SciTech Connect

    Alonso-Herrero, Almudena; Pereira-Santaella, Miguel [Centro de Astrobiologia, INTA-CSIC, E-28850 Torrejon de Ardoz, Madrid (Spain); Rieke, George H. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Rigopoulou, Dimitra [Astrophysics Department, University of Oxford, Oxford OX1 3RH (United Kingdom)

    2012-01-01

    We quantify the active galactic nucleus (AGN) contribution to the mid-infrared (mid-IR) and the total infrared (IR, 8-1000 {mu}m) emission in a complete volume-limited sample of 53 local luminous infrared galaxies (LIRGs, L{sub IR} = 10{sup 11}-10{sup 12} L{sub Sun }). We decompose the Spitzer Infrared Spectrograph low-resolution 5-38 {mu}m spectra of the LIRGs into AGN and starburst components using clumpy torus models and star-forming galaxy templates, respectively. We find that 50% (25/50) of local LIRGs have an AGN component detected with this method. There is good agreement between these AGN detections through mid-IR spectral decomposition and other AGN indicators, such as the optical spectral class, mid-IR spectral features, and X-ray properties. Taking all the AGN indicators together, the AGN detection rate in the individual nuclei of LIRGs is {approx}62%. The derived AGN bolometric luminosities are in the range L{sub bol}(AGN) = (0.4-50) Multiplication-Sign 10{sup 43} erg s{sup -1}. The AGN bolometric contribution to the IR luminosities of the galaxies is generally small, with 70% of LIRGs having L{sub bol}[AGN]/L{sub IR} {<=} 0.05. Only {approx_equal} 8% of local LIRGs have a significant AGN bolometric contribution L{sub bol}[AGN]/L{sub IR} > 0.25. From the comparison of our results with literature results of ultraluminous infrared galaxies (L{sub IR} = 10{sup 12}-10{sup 13} L{sub Sun }), we confirm that in the local universe the AGN bolometric contribution to the IR luminosity increases with the IR luminosity of the galaxy/system. If we add up the AGN bolometric luminosities we find that AGNs only account for 5%{sub -3%}{sup +8%} of the total IR luminosity produced by local LIRGs (with and without AGN detections). This proves that the bulk of the IR luminosity of local LIRGs is due to star formation activity. Taking the newly determined IR luminosity density of LIRGs in the local universe, we then estimate an AGN IR luminosity density of {Omega}{sup AGN}{sub IR} = 3 Multiplication-Sign 10{sup 5} L{sub Sun} Mpc{sup -3} in LIRGs.

  5. Fusion-neutron-yield, activation measurements at the Z accelerator: Design, analysis, and sensitivity

    SciTech Connect

    Hahn, K. D., E-mail: kdhahn@sandia.gov; Ruiz, C. L.; Fehl, D. L.; Chandler, G. A.; Knapp, P. F.; Smelser, R. M.; Torres, J. A. [Sandia National Laboratories, Diagnostics and Target Physics, Albuquerque, New Mexico 87123 (United States)] [Sandia National Laboratories, Diagnostics and Target Physics, Albuquerque, New Mexico 87123 (United States); Cooper, G. W.; Nelson, A. J. [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)] [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Leeper, R. J. [Los Alamos National Laboratories, Plasma Physics Group, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratories, Plasma Physics Group, Los Alamos, New Mexico 87545 (United States)

    2014-04-15

    We present a general methodology to determine the diagnostic sensitivity that is directly applicable to neutron-activation diagnostics fielded on a wide variety of neutron-producing experiments, which include inertial-confinement fusion (ICF), dense plasma focus, and ion beam-driven concepts. This approach includes a combination of several effects: (1) non-isotropic neutron emission; (2) the 1/r{sup 2} decrease in neutron fluence in the activation material; (3) the spatially distributed neutron scattering, attenuation, and energy losses due to the fielding environment and activation material itself; and (4) temporally varying neutron emission. As an example, we describe the copper-activation diagnostic used to measure secondary deuterium-tritium fusion-neutron yields on ICF experiments conducted on the pulsed-power Z Accelerator at Sandia National Laboratories. Using this methodology along with results from absolute calibrations and Monte Carlo simulations, we find that for the diagnostic configuration on Z, the diagnostic sensitivity is 0.037% ± 17% counts/neutron per cm{sup 2} and is ? 40% less sensitive than it would be in an ideal geometry due to neutron attenuation, scattering, and energy-loss effects.

  6. 14.8 MeV Neutron Activation Cross Section Measurements for Ge Isotopes

    Microsoft Academic Search

    M. M. Haque; M. T. Islam; M. A. Hafiz; R. U. Miah; M. S. Uddin

    2009-01-01

    The cross sections of Ge isotopes were measured with the activation method at 14.8 MeV neutron energy. The quasi-monoenergetic neutron beams were produced via the 3 H(d,n) 4 He reaction at the 150 kV J-25 neutron generator of INST, AERE. The characteristics ?-lines of the product nuclei were measured with a closed end coaxial 17.5 cm 2 high purity germanium

  7. Thermal-Neutron Activation Cross Sections of Ge and the Isomeric Ratio Rule

    Microsoft Academic Search

    E. der Mateosian; M. Goldhaber

    1957-01-01

    The thermal-neutron activation cross sections of Ge74 and Ge76 were determined. Contrary to indications obtained from previously published neutron cross-section compilations, our results are in agreement with the isomeric ratio rule, which states that the ratio of cross sections for the production of two isomeric states by slow neutron capture is such that the isomeric state with spin close to

  8. Feasibility of culvert IED detection using thermal neutron activation

    NASA Astrophysics Data System (ADS)

    Faust, Anthony A.; McFee, John E.; Clifford, Edward T. H.; Andrews, Hugh Robert; Mosquera, Cristian; Roberts, William C.

    2012-06-01

    Bulk explosives hidden in culverts pose a serious threat to the Canadian and allied armies. Culverts provide an opportunity to conceal insurgent activity, avoid the need for detectable surface disturbances, and limit the applicability of conventional sub-surface sensing techniques. Further, in spite of the large masses of explosives that can be employed, the large sensor{target separation makes detection of the bulk explosive content challeng- ing. Defence R&D Canada { Sueld and Bubble Technology Industries have been developing thermal neutron activation (TNA) sensors for detection of buried bulk explosives for over 15 years. The next generation TNA sensor, known as TNA2, incorporates a number of improvements that allow for increased sensor-to-target dis- tances, making it potentially feasible to detect large improvised explosive devices (IEDs) in culverts using TNA. Experiments to determine the ability of TNA2 to detect improvised explosive devices in culverts are described, and the resulting signal levels observed for relevant quantities of explosives are presented. Observations conrm that bulk explosives detection using TNA against a culvert-IED is possible, with large charges posing a detection challenge at least as dicult as that of a deeply buried anti-tank landmine. Because of the prototype nature of the TNA sensor used, it is not yet possible to make denitive statements about the absolute sensitivity or detection time. Further investigation is warranted.

  9. Neutron dosimetry and activation on the tokamak Tore-Supra

    SciTech Connect

    Joyer, P.; Martin, G. [Association Euratom-CEA, Saint-Paul-Lez-Durance (France)

    1994-12-31

    In Tore-Supra, neutron productions up to 10{sup 20} neutrons/year are expected. Calculations based on 1-D and 3-D codes have been made before the assembly phase. A strategy has been established to reconcile high neutron levels with the needs of an experimental device, i.e. access to the tokamak. Operation at low power (8.5 10{sup 16} neutrons) has allowed an initial set of measurements, which has been compared to the calculations. Quite good agreement is observed, especially for fast neutrons. A difference for slow neutrons is attributed to a small quantity of boron added in the concrete wall surrounding the experiment and to safety factors in the computations.

  10. Neutron Activation Cool-down of the Tokamak Fusion Test Reactor

    SciTech Connect

    Ascione, G.; Kugel, H.W.; Kumar, A.; Tilson, Jr, C.

    1998-06-10

    Tokamak Fusion Test Reactor (TFTR) final operations and post-shutdown neutron activation measurements were made. Ionization chambers were used to follow TFTR activation during operations and after shutdown. Gamma-ray energy spectroscopy measurements were performed to characterize TFTR activation at accessible vessel-bays and on sample hardware removed from structures at various distances from the vessel. The results demonstrate long-lived activations from common, commercially available materials used in the fabrication and field engineering of TFTR. The measurements allow characterization of residual TFTR neutron activation, the projection of residual activation decay, and benchmarking of low activation issues simulations.

  11. Real-Time Active Cosmic Neutron Background Reduction Methods

    SciTech Connect

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

    2013-09-01

    Neutron counting using large arrays of pressurized 3He proportional counters from an aerial system or in a maritime environment suffers from the background counts from the primary cosmic neutrons and secondary neutrons caused by cosmic ray?induced mechanisms like spallation and charge-exchange reaction. This paper reports the work performed at the Remote Sensing Laboratory–Andrews (RSL-A) and results obtained when using two different methods to reduce the cosmic neutron background in real time. Both methods used shielding materials with a high concentration (up to 30% by weight) of neutron-absorbing materials, such as natural boron, to remove the low-energy neutron flux from the cosmic background as the first step of the background reduction process. Our first method was to design, prototype, and test an up-looking plastic scintillator (BC-400, manufactured by Saint Gobain Corporation) to tag the cosmic neutrons and then create a logic pulse of a fixed time duration (~120 ?s) to block the data taken by the neutron counter (pressurized 3He tubes running in a proportional counter mode). The second method examined the time correlation between the arrival of two successive neutron signals to the counting array and calculated the excess of variance (Feynman variance Y2F)1 in the neutron count distribution from Poisson distribution. The dilution of this variance from cosmic background values ideally would signal the presence of man-made neutrons.2 The first method has been technically successful in tagging the neutrons in the cosmic-ray flux and preventing them from being counted in the 3He tube array by electronic veto—field measurement work shows the efficiency of the electronic veto counter to be about 87%. The second method has successfully derived an empirical relationship between the percentile non-cosmic component in a neutron flux and the Y2F of the measured neutron count distribution. By using shielding materials alone, approximately 55% of the neutron flux from man-made sources like 252Cf or Am-Be was removed.

  12. Real-time active cosmic neutron background reduction methods

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    Neutron counting using large arrays of pressurized 3He proportional counters from an aerial system or in a maritime environment suffers from the background counts from the primary cosmic neutrons and secondary neutrons caused by cosmic ray?induced mechanisms like spallation and charge-exchange reaction. This paper reports the work performed at the Remote Sensing Laboratory-Andrews (RSL-A) and results obtained when using two different methods to reduce the cosmic neutron background in real time. Both methods used shielding materials with a high concentration (up to 30% by weight) of neutron-absorbing materials, such as natural boron, to remove the lowenergy neutron flux from the cosmic background as the first step of the background reduction process. Our first method was to design, prototype, and test an up-looking plastic scintillator (BC-400, manufactured by Saint Gobain Corporation) to tag the cosmic neutrons and then create a logic pulse of a fixed time duration (~120 ?s) to block the data taken by the neutron counter (pressurized 3He tubes running in a proportional counter mode). The second method examined the time correlation between the arrival of two successive neutron signals to the counting array and calculated the excess of variance (Feynman variance Y2F)1 in the neutron count distribution from Poisson distribution. The dilution of this variance from cosmic background values ideally would signal the presence of manmade neutrons.2 The first method has been technically successful in tagging the neutrons in the cosmic-ray flux and preventing them from being counted in the 3He tube array by electronic veto—field measurement work shows the efficiency of the electronic veto counter to be about 87%. The second method has successfully derived an empirical relationship between the percentile non-cosmic component in a neutron flux and the Y2F of the measured neutron count distribution. By using shielding materials alone, approximately 55% of the neutron flux from man-made sources like 252Cf or Am-Be was removed.

  13. Investigation of the microstructure of alkali-activated cements by neutron scattering

    Microsoft Academic Search

    J. W. Phair; J. C. Schulz; W. K. Bertram; L. P. Aldridge

    2003-01-01

    Significant research has been devoted to understanding and modeling the neutron scattering behavior of Portland cement pastes. The present work examines the potential of neutron scattering to noninvasively evaluate the properties of alternative cementitious materials encountered in the field. To interpret the scattering of both alkali-activated and slag-cement systems, alternative models to those typically adopted for Portland cement pastes were

  14. Neutron activation analysis of saliva: Application in clinical chemistry, environmental and occupational toxicology

    Microsoft Academic Search

    V. Zaichick; A. Tsyb; S. Bagirov

    1995-01-01

    The contents of 21 chemical elements (Ag, Br, Ca, Cl, Co, Cr, Cs, Fe, Hg, K, Mg, Mn, N, Na, P, Rb, Sb, Sc, Se, Sr, Zn) in mixed non-stimulated saliva of 52 relatively healthy people were assessed by activation using 14 MeV neutrons and nuclear reactor neutrons. The study included 45 women and 7 men, aged 18 to 35.

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

    SciTech Connect

    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.

  16. Thermal and 14.4 MeV neutron activation cross sections of argon

    Microsoft Academic Search

    N. Ranakumar; E. Karttunen; R. W. Fink

    1969-01-01

    Thermal and 14.4 MeV neutron activation cross sections of argon were measured with argon quinol-clathrate powder as target material. The thermal neutron activation cross section of the 40Ar(n, gamma)41Ar reaction was measured to be 510+\\/-25 mb. The 14.4+\\/-0.3 MeV neutron activation cross sections for the reactions 38Ar(n,p)38Cl, 40Ar(n,p)40Cl(1.4 min), 40Ar (n, np+n, pn+n, d)39Cl and 40Ar(n, alpha)37S were measured to

  17. Manufacture and properties of erythromycin beads containing neutron-activated erbium-171

    SciTech Connect

    Parr, A.F.; Digenis, G.A.; Sandefer, E.P.; Ghebre-Sellassie, I.; Iyer, U.; Nesbitt, R.U.; Scheinthal, B.M. (Univ. of Kentucky, Lexington (USA))

    1990-03-01

    To evaluate the effects of a neutron activation radiolabeling technique on an enteric-coated multiparticulate formulation of erythromycin, test quantities were produced under industrial pilot scale conditions. The pellets contained the stable isotope erbium oxide (Er-170), which was later converted by neutron activation into the short-lived gamma ray-emitting radionuclide, erbium-171. In vitro studies indicated that the dissolution profile, acid resistance, and enteric-coated surface of the pellets were minimally affected by the irradiation procedure. Antimicrobial potency was also unaffected, as determined by microbiological assay. Neutron activation thus appears to simplify the radiolabeling of complex pharmaceutical dosage forms for in vivo study by external gamma scintigraphy.

  18. Gamma-ray-spectroscopy following high-flux 14-MeV neutron activation

    SciTech Connect

    Williams, R.E.

    1981-10-12

    The Rotating Target Neutron Source (RTNS-I), a high-intensity source of 14-MeV neutrons at the Lawrence Livermore National Laboratory (LLNL), has been used for applications in activation analysis, inertial-confinement-fusion diagnostic development, and fission decay-heat studies. The fast-neutron flux from the RTNS-I is at least 50 times the maximum fluxes available from typical neutron generators, making these applications possible. Facilities and procedures necessary for gamma-ray spectroscopy of samples irradiated at the RTNS-I were developed.

  19. Fast-Neutron Activation of Long-Lived Nuclides in Natural Pb

    E-print Network

    V. E. Guiseppe; S. R. Elliott; N. E. Fields; D. Hixon

    2012-09-20

    We measured the production of the long-lived nuclides Bi-207, Pb-202, and Hg-194 in a sample of natural Pb due to high-energy neutron interactions using a neutron beam at the Los Alamos Neutron Science Center. The activated sample was counted by a HPGe detector to measure the amount of radioactive nuclides present. These nuclides are critical in understanding potential backgrounds in low background experiments utilizing large amounts of Pb shielding due to cosmogenic neutron interactions in the Pb while residing on the Earth's surface. By scaling the LANSCE neutron flux to a cosmic neutron flux, we measure the sea level cosmic ray production rates of 8.0 +/- 1.3 atoms/kg/day of Hg-194, 120 +/- 25 atoms/kg/day Pb-202, and 0.17 +/- 0.04 atoms/kg/day Bi-207.

  20. A neutron activation technique for manganese measurements in humans.

    PubMed

    Bhatia, C; Byun, S H; Chettle, D R; Inskip, M J; Prestwich, W V

    2015-07-01

    Manganese (Mn) is an essential element for humans, animals, and plants and is required for growth, development, and maintenance of health. Studies show that Mn metabolism is similar to that of iron, therefore, increased Mn levels in humans could interfere with the absorption of dietary iron leading to anemia. Also, excess exposure to Mn dust, leads to nervous system disorders similar to Parkinson's disease. Higher exposure to Mn is essentially related to industrial pollution. Thus, there is a benefit in developing a clean non-invasive technique for monitoring such increased levels of Mn in order to understand the risk of disease and development of appropriate treatments. To this end, the feasibility of Mn measurements with their minimum detection limits (MDL) has been reported earlier from the McMaster group. This work presents improvement to Mn assessment using an upgraded system and optimized times of irradiation and counting for induced gamma activity of Mn. The technique utilizes the high proton current Tandetron accelerator producing neutrons via the (7)Li(p,n)(7)Be reaction at McMaster University and an array of nine NaI (Tl) detectors in a 4? geometry for delayed counting of gamma rays. The neutron irradiation of a set of phantoms was performed with protocols having different proton energy, current and time of irradiation. The improved MDLs estimated using the upgraded set up and constrained timings are reported as 0.67?gMn/gCa for 2.3MeV protons and 0.71?gMn/gCa for 2.0MeV protons. These are a factor of about 2.3 times better than previous measurements done at McMaster University using the in vivo set-up. Also, because of lower dose-equivalent and a relatively close MDL, the combination of: 2.0MeV; 300?A; 3min protocol is recommended as compared to 2.3MeV; 400?A; 45s protocol for further measurements of Mn in vivo. PMID:25169978

  1. Improved mesh based photon sampling techniques for neutron activation analysis

    SciTech Connect

    Relson, E.; Wilson, P. P. H.; Biondo, E. D. [University of Wisconsin-Madison, 1500 Engineering Drive, Madison, WI 53706 (United States)

    2013-07-01

    The design of fusion power systems requires analysis of neutron activation of large, complex volumes, and the resulting particles emitted from these volumes. Structured mesh-based discretization of these problems allows for improved modeling in these activation analysis problems. Finer discretization of these problems results in large computational costs, which drives the investigation of more efficient methods. Within an ad hoc subroutine of the Monte Carlo transport code MCNP, we implement sampling of voxels and photon energies for volumetric sources using the alias method. The alias method enables efficient sampling of a discrete probability distribution, and operates in 0(1) time, whereas the simpler direct discrete method requires 0(log(n)) time. By using the alias method, voxel sampling becomes a viable alternative to sampling space with the 0(1) approach of uniformly sampling the problem volume. Additionally, with voxel sampling it is straightforward to introduce biasing of volumetric sources, and we implement this biasing of voxels as an additional variance reduction technique that can be applied. We verify our implementation and compare the alias method, with and without biasing, to direct discrete sampling of voxels, and to uniform sampling. We study the behavior of source biasing in a second set of tests and find trends between improvements and source shape, material, and material density. Overall, however, the magnitude of improvements from source biasing appears to be limited. Future work will benefit from the implementation of efficient voxel sampling - particularly with conformal unstructured meshes where the uniform sampling approach cannot be applied. (authors)

  2. Analysis of body calcium (regional changes in body calcium by in vivo neutron activation analysis)

    NASA Technical Reports Server (NTRS)

    Suki, W.; Johnson, P. C.; Leblanc, A.; Evans, H. J.

    1981-01-01

    The effect of space flight on urine and fecal calcium loss was documented during the three long-term Skylab flights. Neutron activation analysis was used to determine regional calcium loss. Various designs for regional analysis were investigated.

  3. Active mode calibration of the combined thermal epithermal neutron (CTEN) system

    SciTech Connect

    Veilleux, J. M. (John M.)

    2001-01-01

    The Combined Thermal Epithermal Neutron (CTEN) system was developed by the Los Alamos National Laboratory to perform active and passive neutron interrogation of waste. The higher energy epithermal neutrons are able to penetrate further into the matrix and active material, thus reducing matrix attenuation and self-shielding effects compared to a thermal neutron pulse alone. The developmental unit was installed in 2001 at the Los Alamos Non-Destructive Assay (NDA) facility to characterize waste for the TRU Waste Characterization Project (TWCP). This paper summarizes the active mode certification results. National Institute of Standards and Technology (NIST) traceable standards were used to determine the system response as a function of mass. Finally, NIST-traceable verification standards were used to verify the calibration in the range 30 milligrams to 25 g of weapons grade plutonium although self-shielding limits the upper active interrogation to 10 g.

  4. Threshold Reaction Rates and Energy Spectra of Neutrons in the 0.8-1.6 GeV Proton-Irradiated W, Na Targets

    E-print Network

    Yury E. Titarenko; Vyacheslav F. Batyaev; Evgeny I. Karpikhin; Valery M. Zhivun; Svetlana V. Kvasova; Ruslan D. Mulambetov; Dmitry V. Fischenko; Aleksander B. Koldobsky; Yury V. Trebukhovsky; Vladimir A. Korolev; Gennady N. Smirnov; Andrey M. Voloshenko; Vladimir Yu. Belov; Nikolay I. Kachalin Stepan G. Mashnik; Richard E. Prael; Arnold J. Sierk; Hideshi Yasuda

    2002-08-30

    Considering the prospects of using the W-Na target assemblies in ADS facilities, the experiments were made to study the nuclear-physics characteristics of W and Na, and the composite structures thereof in their interactions with 0.8-GeV and 1.6-GeV protons. The neutron and proton-induced reaction rates were measured inside, and on the surface of, a cylinder-shaped heterogeneous W-Na assembly together with the double-differential spectra of secondary neutrons emitted from different-depth W and Na discs. The measurement results were simulated by the LAHET, CEM2k, and KASKAD-S codes in terms of the latest versions of nuclear databases.

  5. Preparation of Neutron-activated Xenon for Liquid Xenon Detector Calibration

    E-print Network

    Ni, K; Wongjirad, T M; Kastens, L; Manzur, A; McKinsey, D N

    2007-01-01

    We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a five-day activation of natural xenon gas with a Cf-252 (4 x 10^5 n/s) source, the activities of two gamma ray lines at 164 keV and 236 keV, from Xe-131m and Xe-129m metastable states, were measured at about 95 and 130 Bq/kg, respectively. We also observed three additional lines at 35 keV, 100 keV and 275 keV, which decay away within a few days. No long-lifetime activity was observed after the neutron activation.

  6. Prompt gamma ray neutron activation analysis of cadmium in municipal solid waste 

    E-print Network

    Dendahl, Katherine Hoge

    1991-01-01

    PROMPT GAMMA RAY NEUTRON ACTIVATION ANALYSIS OF CADMIUM IN MUNICIPAL SOLID WASTE A Thesis by KATHERINE HOGE DENDAHL Submitted to the Office of Graduate Studies of Texas ASM University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE December 1991 Major Subject: Industrial Hygiene PROMPT GAMMA RAY NEUTRON ACTIVATION ANALYSIS OP CADMIUM IN MUNICIPAL SOLID WASTE A Thesis by KATHERINE HOGE DENDAHL Approved as to style and content by: Ric rd B. K nz (Chair...

  7. Non-destructive determination of aluminum in biological reference samples using neutron activation analysis

    Microsoft Academic Search

    S. Landsberger; A. M. Arendt

    1989-01-01

    The non-destructive methods of thermal and epithermal neutron activation analysis have been employed to determine the aluminum concentration of seven National Institute of Standards and Technology certified biological reference materials. Through the judicious use of both thermal and epithermal neutron activation analysis using bare and boron-lined irradiation carriers, the major and minor contributions of the31P\\/n, \\/28Al and of the28Si\\/n, p\\/28Al

  8. Neutron Activation Cross Section of Molybdenum Isotopes at 14.8 MeV

    Microsoft Academic Search

    Susumu AMEMIYA; Kei-ichi ISHIBASHI; Toshio KATOH

    1982-01-01

    The neutron activation cross sections of Mo isotopes have been measured for the 14.8 MeV neutron. The cross sections have been determined with reference to the known A1 (n, ?)Na and the Al(n, p)Mg reactions. The cyclic activation method was employed for the ?-ray measurement of short-lived nuclei. A 55 cm Ge(Li) detector was used for the measurement of ?-ray

  9. Neutron activation analysis of dental metals with regard to forensic odontology (dental identification)

    Microsoft Academic Search

    K. Rötzscher; S. Mende; J. Flachowsky; M. Geisler; H.-J. Wehran

    1973-01-01

    In cases of complicated identifications the neutron activation analysis of dental metals may inform more than usual descriptions\\u000a of the teeth including X-rays. Identifications would become more effective in the field of forensic stomatology by adding\\u000a “pilot” elements into the alloys of dental metals by the factories. The neutron activation analysis of dental metals from\\u000a Halsbrücke (GDR) are discussed and

  10. EChO spectra and stellar activity II. The case of dM stars

    NASA Astrophysics Data System (ADS)

    Scandariato, Gaetano; Micela, Giuseppina

    2014-05-01

    EChO a dedicated mission to investigate exoplanetary atmospheres. When extracting the planetary signal, one has to take care of the variability of the hosting star, which introduces spectral distortion that can be mistaken as planetary signal. Magneticvariability has to be taken into account in particular for M stars. To this purpose, assuming a one spot dominant model for the stellar photosphere, we develop a mixed observational-theoretical tool to extract the spot's parameters from the observed optical spectrum. This method relies on a robust library of spectral M templates, which we derive using the observed spectra of quiet M dwarfs in the SDSS database. Our procedure allows to correct the observed spectra for photospheric activity in most of the analyzed cases, reducing the spectral distortion down to the noise levels. Ongoing refinements of the template library and the algorithm will improve the efficiency of our algorithm.

  11. Electron-positron pairs, Compton reflection, and the X-ray spectra of active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Zdziarski, Andrzej A.; Ghisellini, Gabriele; George, Ian M.; Fabian, A. C.; Svensson, Roland; Done, Chris

    1990-01-01

    It is shown here that reprocessing of radiation fron nonthermal pair cascades by cold material in the central parts of active galactic nuclei (AGN) gives rise to X-ray and gamma-ray spectra that satisfy current observational constraints. An average 1-30 keV X-ray spectral index alpha(x) of about 0.7 in the compact range 30-300 is obtained for a wide range of Lorentz factors of the injected electrons. The gamma-ray spectra are steep, with alpha(gamma) about two, and satisfy the observational constraints. Radiation from pair cascades exhibits steep power law decreases in soft X-rays similar to those observed in AGN. The overall picture is consistent with AGN having an accretion disk which intercepts and reprocesses a substantial fraction of the nonthermal continuum incident upon it from above and below.

  12. X-ray irradiation of interstellar grains in active galaxies - Evaporation and infrared spectra

    NASA Technical Reports Server (NTRS)

    Voit, G. M.

    1991-01-01

    A fundamental physical study of grains heated transiently by X-rays is presented. The X-ray photoionization cross sections used to determine the rate of energy deposition into the grains are given. A grain model is constructed and the radiative and evaporative responses of grains into X-ray absorption are described. The basic theory of stochastic grain heating is outlined, and analytical expressions for the temperature distributions of flickering grains are provided. The resulting IR spectra due to X-ray illumination are given, and the relevance of the present work to the IR continua of active galaxies is discussed. The present model provides two observational predictions: the infrared spectra of grains, even if they are superheated, should show a cutoff between 1 and 3 microns; and X-ray-illuminated environments should exhibit no PAH emissions.

  13. Bayesian calibration of reactor neutron flux spectrum using activation detectors measurements: Application to CALIBAN reactor

    SciTech Connect

    Cartier, J. [Commissariat a l'Energie Atomique et aux Energies Alternatives CEA, DAM, DIF, F-91297 Arpajon (France); Casoli, P. [Commissariat a l'Energie Atomique et aux Energies Alternatives CEA, DAM, Valduc, F-21120 Is sur Tille (France); Chappert, F. [Commissariat a l'Energie Atomique et aux Energies Alternatives CEA, DAM, DIF, F-91297 Arpajon (France)

    2013-07-01

    In this paper, we present calibration methods in order to estimate reactor neutron flux spectrum and its uncertainties by using integral activation measurements. These techniques are performed using Bayesian and MCMC framework. These methods are applied to integral activation experiments in the cavity of the CALIBAN reactor. We estimate the neutron flux and its related uncertainties. The originality of this work is that these uncertainties take into account measurements uncertainties, cross-sections uncertainties and model error. In particular, our results give a very good approximation of the total flux and indicate that neutron flux from MCNP simulation for energies above about 5 MeV seems to overestimate the 'real flux'. (authors)

  14. Active Neutron Interrogation to Detect Shielded Fissionable Material

    Microsoft Academic Search

    D. L. Chichester; E. H. Seabury

    2009-01-01

    Portable electronic neutron generators (ENGs) may be used to interrogate suspicious items to detect, characterize, and quantify the presence fissionable material based upon the measurement of prompt and\\/or delayed emissions of neutrons and\\/or photons resulting from fission. The small size (<0.2 m3), light weight (<12 kg), and low power consumption (<50 W) of modern ENGs makes them ideally suited for

  15. Comparison of Impurities in Charcoal Sorbents Found by Neutron Activation Analysis

    SciTech Connect

    Doll, Charles G.; Finn, Erin C.; Cantaloub, Michael G.; Greenwood, Lawrence R.; Kephart, Jeremy; Kephart, Rosara F.

    2013-01-01

    Abstract: Neutron activation of gas samples in a reactor often requires a medium to retain sufficient amounts of the gas for analysis. Charcoal is commonly used to adsorb gas and hold it for activation; however, the amount of activated sodium in the charcoal after irradiation swamps most signals of interest. Neutron activation analysis (NAA) was performed on several commonly available charcoal samples in an effort to determine the activation background. The results for several elements, including the dominant sodium element, are reported. It was found that ECN charcoal had the lowest elemental background, containing sodium at 2.65 ± 0.05 ppm, as well as trace levels of copper and tungsten.

  16. Neutron radiography activity in the european program cost 524: Neutron imaging techniques

    NASA Astrophysics Data System (ADS)

    Chirco, P.; Bach, P.; Lehmann, E.; Balasko, M.

    2001-07-01

    COST is a framework for scientific and technical cooperation, allowing the coordination of national research on a European level, including 32 member countries. Participation of institutes from non-COST countries is possible. From an initial 7 Actions in 1971, COST has grown to 200 Actions at the beginning of 2000. COST Action 524 is under materials domain, the title of which being "Neutron Imaging Techniques for the Detection of Defects in Materials", under the Chairmanship of Dr. P. Chirco (I.N.F.N.). The following countries are represented in the Management Committee of Action 524: Italy, France, Austria, Germany, United Kingdom, Hungary, Switzerland, Spain, Czech Republic, Slovenia, and Russia. The six working groups of this Action are working respectively on standardization of neutron radiography techniques, on aerospace application, on civil engineering applications, on comparison and integration of neutron imaging techniques with other NDT, on neutron tomography, and on non radiographic techniques such as neutron scattering techniques. A specific effort is devoted to standardization issues, with respect to other non European standards. Results of work performed in the COST frame are published or will be published in the review INSIGHT, edited by the British Institute of Non Destructive Testing.

  17. In-situ soil composition and moisture measurement by surface neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Waring, C.; Smith, C.; Marks, A.

    2009-04-01

    Neutron activation analysis is widely known as a laboratory technique dependent upon a nuclear reactor to provide the neutron flux and capable of precise elemental analysis. Less well known in-situ geochemical analysis is possible with isotopic (252Cf & 241Am) or compact accelerator (D-T, D-D fusion reaction) neutron sources. Prompt gamma neutron activation analysis (PGNAA) geophysical borehole logging has been applied to mining issues for >15 years (CSIRO) using isotopic neutron sources and more recently to environmental and hydro-geological applications by ANSTO. Similarly, sophisticated geophysical borehole logging equipment based on inelastic neutron scattering (INS) has been applied in the oil and gas industry by large oilfield services companies to measure oil saturation indices (carbon/oxygen) using accelerator neutron sources. Recent advances in scintillation detector spectral performance has enabled improved precision and detection limits for elements likely to be present in soil profiles (H, Si, Al, Fe, Cl) and possible detection of many minor to trace elements if sufficiently abundant (Na, K, Mg, Ca, S, N, + ). To measure carbon an accelerator neutron source is required to provide fast neutrons above 4.8 MeV. CSIRO and ANSTO propose building a soil geochemical analysis system based on experience gained from building and applying PGNA borehole logging equipment. A soil geochemical analysis system could effectively map the 2D geochemical composition of the top 50cm of soil by dragging the 1D logging equipment across the ground surface. Substituting an isotopic neutron source for a D-T accelerator neutron source would enable the additional measurement of elemental carbon. Many potential ambiguities with other geophysical proxies for soil moisture may be resolved by direct geochemical measurement of H. Many other applications may be possible including time series in-situ measurements of soil moisture for differential drainage, hydrology, land surface parameter models, fertiliser distribution, leaching and mobility characteristics and measuring carbon sequestration or loss from different land use practices.

  18. Quantitative comparison between experimental and simulated gamma-ray spectra induced by 14 MeV tagged neutrons.

    PubMed

    Perot, B; El Kanawati, W; Carasco, C; Eleon, C; Valkovic, V; Sudac, D; Obhodas, J; Sannie, G

    2012-07-01

    Fast neutron interrogation with the associated particle technique can be used to identify explosives in cargo containers (EURITRACK FP6 project) and unexploded ordnance on the seabed (UNCOSS FP7 project), by detecting gamma radiations induced by 14 MeV neutrons produced in the 2H(3H,?)n reaction. The origin of the gamma rays can be determined in 3D by the detection of the alpha particle, which provides the direction of the opposite neutron and its time-of-flight. Gamma spectroscopy provides the relative counts of carbon, nitrogen, and oxygen, which are converted to chemical fractions to differentiate explosives from other organic substances. To this aim, Monte Carlo calculations are used to take into account neutron moderation and gamma attenuation in cargo materials or seawater. This paper presents an experimental verification that C, N, and O counts are correctly reproduced by numerical simulation. A quantitative comparison is also reported for silicon, iron, lead, and aluminium. PMID:21782459

  19. Quantitative comparison between experimental and simulated gamma-ray spectra induced by 14 MeV tagged neutrons

    Microsoft Academic Search

    B. Perot; W. El Kanawati; C. Carasco; C. Eleon; V. Valkovic; D. Sudac; J. Obhodas; G. Sannie

    Fast neutron interrogation with the associated particle technique can be used to identify explosives in cargo containers (EURITRACK FP6 project) and unexploded ordnance on the seabed (UNCOSS FP7 project), by detecting gamma radiations induced by 14MeV neutrons produced in the 2H(3H,?)n reaction. The origin of the gamma rays can be determined in 3D by the detection of the alpha particle,

  20. Response of thunderstorm activity in data of neutron monitoring at Tien Shan

    NASA Astrophysics Data System (ADS)

    Antonova, Valentina; Kryukov, Sergey; Lutsenko, Vadim

    2015-04-01

    We present results of the study of data of the monitoring of high-energy and thermal neutrons at Tien Shan at different stages of thunderstorm activity. The data of the neutron monitoring were used taking into account the barometric effect. The intensity of the neutron component of cosmic rays is recorded in seven energy ranges. The electric field has values of ~ 100 V/m under fair weather conditions. Standard deviation of minute values of the neutron monitor data at the high altitude station does not exceed 0.5-0.6 %. Found that the standard deviation of the data during thunderstorms always exceeds these values. We selected events during the passage of thunderstorm clouds over the high altitude station without lightning discharges or with a small number of them. It was found that the particle rate of the neutron monitor changes in antiphase with the electric field changes. Atmospheric electric field of positive polarity decreases the count rate of the neutron monitor, and negative polarity - increases. Change of the count rate occurs at values of electric field ? 10-15 kV/m and reaches 2 %. The neutron monitor at the high-altitude station has the ability to measure the energy of recorded particles through determination of their multiplicity. We experimentally established that the sensitivity of the detected particles to change in Ez increases with decreasing their energy. The upper energy threshold of sensitivity of neutrons to change electric field is ~10 GeV. The physical mechanism of effect is based on lead nucleus capture of soft negative muons with the subsequent generation of neutrons. It is known that 7% of the neutron monitor count rate caused by negative muons. Absence of this effect in thermal neutrons data confirms the conclusion since the main difference of the thermal neutrons detector from the neutron monitor is the absence of the lead. In the active phase of a thunderstorm in the formed thundercloud the picture of distribution of charges is complex and multilayered. The field on the ground can essentially differ from the field that caused the acceleration or deceleration of negative muons. It is possible the occurrence of the nuclear processes caused by lightning, - all this complicates interpretation of the monitor data. However, together with the system of electric field detectors, the neutron monitor allows to expand possibilities for determining the structure of thunderclouds. Recorded at the Tine Shan, as well as at other stations, bursts of both slow and fast neutrons during lightning discharges attract undoubted interest. However, their nature is still discussed.

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

    Microsoft Academic Search

    W. V. Nunes; A. X. da Silva; V. R. Crispim; R. Schirru

    2002-01-01

    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

  2. Evaluation of the Doppler-Broadening of Gamma-Ray Spectra from Neutron Inelastic Scattering on Light Nuclei

    NASA Astrophysics Data System (ADS)

    Womble, Phillip C.; Barzilov, Alexander; Novikov, Ivan; Howard, Joseph; Musser, Jason

    2009-03-01

    Neutron-induced gamma-ray reactions are extensively used in the nondestructive analysis of materials and other areas where the information about the chemical composition of a substance is crucial. The common technique to find the intensity of the gamma ray is to fit gamma-ray line shape with an analytical function, for example, a Gaussian. However, the Gaussian fitting may fail if the gamma-ray peak is Doppler-broadened since this leads to the miscalculation of the area of the peak and, therefore, to misidentification of the material. Due to momentum considerations, Doppler-broadening occurs primarily with gamma rays from neutron-induced inelastic scattering reactions with light nuclei. The recoiling nucleus of interest must have excited states whose lifetimes are much smaller than the time of flight in the material. We have examined various light nuclei bombarded by 14 MeV neutrons to predict when the peak shape of a neutron-induced gamma ray emitted from these nuclei will be Doppler-broadened. We have found that nearly all the gamma rays from neutron-induced gamma-ray reactions on light elements (A<20) are Doppler-broadened with only a few exceptions. This means that utilization of resolution curves derived from isotopic sources or thermal neutron capture reactions have little value in the analysis.

  3. A SEARCH FOR IRON EMISSION LINES IN THE CHANDRA X-RAY SPECTRA OF NEUTRON STAR LOW-MASS X-RAY BINARIES

    E-print Network

    Cackett, E. M.

    While iron emission lines are well studied in black hole systems, both in X-ray binaries and active galactic nuclei, there has been less of a focus on these lines in neutron star low-mass X-ray binaries (LMXBs). However, ...

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

    E-print Network

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

    2015-01-01

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

  5. 3He neutron detector design for active detection of cargo containers

    NASA Astrophysics Data System (ADS)

    McDevitt, Daniel B.; Eberhard, J. W.; Zelakiewicz, Scott; Maschinot, Aaron

    2008-04-01

    We report on the design of a neutron detector using industry standard 3He tubes to count delayed neutrons during the interrogation of cargo containers for the presence of Special Nuclear Material (SNM). Simulations of the detector design were run for delayed neutron spectra for a variety of cargos containing SNM using the Monte Carlo computer code COG. The simulations identified parameters crucial to optimize the detector design. These choices include moderating material type and thickness, tube spacing, tube pressure and number of tubes. An experimental prototype was also constructed based on the simulated design specifications. This paper discusses the parameters that lead up to the optimized detector design. It also compares the performance of the Monte Carlo simulated design and the experimental detector when exposed to a 239Pu-Be source.

  6. ORACT: a 174-neutron-group activation cross-section library for fusion and fission reactor design studies

    Microsoft Academic Search

    R. T. Santoro; J. E. White; J. D. Drischler

    1984-01-01

    A 174-neutron-group activation cross-section library for 233 ground-state target isotopes and 22 isomeric target isotopes is described. The library, ORACT, was derived from the ACTL Evaluated Neutron Activation Cross-Section Library and was developed for use with existing computer codes that calculate induced activation by convoluting the cross-section data with neutron scalar flux distributions. The activation cross sections extend over the

  7. Measurement of angular distribution of neutron flux for the 6 MeV race-track microtron based pulsed neutron source

    Microsoft Academic Search

    B. J. Patil; S. T. Chavan; S. N. Pethe; R. Krishnan; S. D. Dhole

    2010-01-01

    The 6MeV race track microtron based pulsed neutron source has been designed specifically for the elemental analysis of short lived activation products, where the low neutron flux requirement is desirable. Electrons impinges on a e–? target to generate bremsstrahlung radiations, which further produces neutrons by photonuclear reaction in ?–n target. The optimisation of these targets along with their spectra were

  8. NEUTRON ACTIVATION CROSS-SECTIONS WITH 14.8 MEV NEUTRONS IN THE REGION OF THE 82NEUTRON CLOSED SHELL (thesis)

    Microsoft Academic Search

    Wille

    1959-01-01

    Fifty activation cross sections for (n,p), (n,q), and (n,2n) reactions ; on 27 stable nuclides of elements Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Er, Yb, and ; Lu were measured using 14.8 plus or minus 0.8 Mev neutrons from the T(d,n)He\\/; sup 4\\/ reaction. Total fluxes of 10¹° to l0¹¹ n\\/sec were obtained ; from the University

  9. Determination of the average neutron activation cross section with an annular-shaped 241 Am\\/Be neutron source and a Nal(T1) detector for the 27 Al (n,p)27 Mg-reaction

    Microsoft Academic Search

    R. Rieppo

    1984-01-01

    The average neutron activation cross section was determined with an annular-shaped 241 Am\\/Be neutron source and an Nal(T1) detector. The calculated average neutron flux in the center of the cavity space of the source is used with the experimental data to give the average neutron activation cross section for the 27Al(n,p)27Mg reaction. The mean value of the measured neutron activation

  10. DOSE PROFILE MODELING OF IDAHO NATIONAL LABORATORY’S ACTIVE NEUTRON INTERROGATION TEST FACILITY

    SciTech Connect

    D. L. Chichester; E. H. Seabury; J. M. Zabriskie; J. Wharton; A. J. Caffrey

    2009-06-01

    A new research and development laboratory has been commissioned at Idaho National Laboratory for performing active neutron interrogation research and development. The facility is designed to provide radiation shielding for DT fusion (14.1 MeV) neutron generators (2 x 108 neutrons per second), DD fusion (2.5 MeV) neutron generators (up to 2 x 106 neutrons per second), and 252Cf spontaneous fission neutron sources (6.7 x 107 neutrons per second, 30 micrograms). Shielding at the laboratory is comprised of modular concrete shield blocks 0.76 m thick with tongue-in-groove features to prevent radiation streaming, arranged into one small and one large test vault. The larger vault is designed to allow operation of the DT generator and has walls 3.8 m tall, an entrance maze, and a fully integrated electrical interlock system; the smaller test vault is designed for 252Cf and DD neutron sources and has walls 1.9 m tall and a simple entrance maze. Both analytical calculations and numerical simulations were used in the design process for the building to assess the performance of the shielding walls and to ensure external dose rates are within required facility limits. Dose rate contour plots have been generated for the facility to visualize the effectiveness of the shield wall and entrance maze and to illustrate the spatial profile of the radiation dose field above the facility and the effects of skyshine around the vaults.

  11. A precise method to determine the activity of a weak neutron source using a germanium detector

    E-print Network

    Duke, M J M; Krauss, C B; Mekarski, P; Sibley, L

    2015-01-01

    A standard high purity germanium detector (HPGe) was used to determine the neutron activity of a weak americium-beryllium (AmBe) neutron source. Gamma rays were created through 27Al(n,n'), 27Al(n,gamma) and 1H(n,gamma) reactions induced by the neutrons on aluminum and acrylic disks. A Monte Carlo simulation was developed to model the efficiency of the detector system. The activity of our neutron source was determined to be 305.6 +/- 4.9 n/s. The result is consistent for the different gamma rays and was verified using additional simulations and measurements of the 4483 keV gamma ray produced directly from the AmBe source.

  12. A portable active interrogation system using a switchable AmBe neutron source

    NASA Astrophysics Data System (ADS)

    Allen, Matthew; Hertz, Kristin; Kunz, Christopher; Mascarenhas, Nicholas

    2005-09-01

    Active neutron interrogation is an effective technique used to locate fissionable material. This paper discusses a portable system that utilizes a AmBe neutron source. The AmBe source consists of an americium alpha source and a beryllium target that can be switched into alignment to turn the source on and out of alignment to turn the source off. This offers a battery operated backpack portable source. The detector system that has been fabricated for use with this source is a fifteen tube 3He neutron detector. The results of initial experiments with the detector and MCNP calculations are discussed.

  13. Physics of solar neutron production: Questionable detection of neutrons

    E-print Network

    Share, Gerald

    Physics of solar neutron production: Questionable detection of neutrons from the 31 December 2007V solar neutrons. We discuss the cross sections for neutron production in solar flares and calculate the escaping neutron spectra for monoenergetic and power law particle spectra at the Sun and at the distance (0

  14. Fast neutron spectra produced by a 49 MeV deuteron-beryllium reaction and its modification by selected absorbers 

    E-print Network

    Hertel, Nolan Elmer

    1975-01-01

    2 0 I M 1. 5 K K 4J 7 1. 0 0. 0 10 20 30 II0 50 60 hlfUTHCIN ENCRGT (NCV) Figure 20. Neutron Spectrum at 0 for the Straight Bore 0 Collimator after Passage Through 20 cm of TE Liquid. 1. 2 1. 0 ) 4J . 8 I IL . 6 I K ca 0. 0 0... 10 20 30 LLO 50 60 hlEUTFIQN ENEAGT (KIEV) 0 Figure 16. Neutron Spectrum at 0 for the Straight Bore Collimator after Passage Through 4 cm of TE Liquid. 1Z 10 ) 4J X: Q I ES7 lo EC) K r cn 4 UJ 10 ZO 30 40 50 50 NEUTRON fNERGT (MEVJ...

  15. Parametric evaluation of active neutron interrogation for the detection of shielded highly-enriched uranium in the field

    Microsoft Academic Search

    David L. Chichester; Scott J. Thompson; Edward H. Seabury; Ryan R. C. Clement

    2011-01-01

    Parametric studies using numerical simulations are being performed to assess the performance capabilities and limits of active neutron interrogation for detecting shielded highly enriched uranium (HEU). Varying the shield material, HEU mass, HEU depth inside the shield, and interrogating neutron source energy, the simulations account for both neutron and photon emission signatures from the HEU with resolution in both energy

  16. Determination of rare earth elements in bauxites by instrumental neutron activation analysis

    Microsoft Academic Search

    P. Vukoti?

    1983-01-01

    The instrumental neutron activation analysis method was used for determination of 12 rare earth elements in red and white\\u000a bauxites. Consideration was given to those systematic errors which in a relative method of analysis can result from the effects\\u000a of neutron self-shielding, photon self-absorption and fission interfering reactions, due to different chemical composition\\u000a of bauxite samples and the standard of

  17. Measurement of neutron spectra for determining dose equivalent rates at the Texas A&M University Nuclear Science Center 

    E-print Network

    Sanza, Bruce Jerome

    1986-01-01

    for 1 week. b. Ninety percent humidity for 1 week. c. Mechanical shock from a 1. 5 m drop. d. Exposure to light during use. of neutron levels this device relies on the detection of proton tracks in a thin photographic emulsion. These tracks.... Piesch, B. Burgkhardt, 1985, "Albedo Neutron D I t y", R di I P t' 0~It 10:175 ? 188. Po85 Ro55 Ro68 Poston, J. W. , 1985, Personal Communication H. H. Rossi, W. Rosenzweig, 1955, "A Device for the Measurement of Dose as a Function of Specif ic I...

  18. Determination of aluminium, silicon and magnesium in geological matrices by delayed neutron activation analysis based on k0 instrumental neutron activation analysis.

    PubMed

    Baidoo, I K; Dampare, S B; Opata, N S; Nyarko, B J B; Akaho, E H K; Quagraine, R E

    2013-12-01

    In this work, concentrations of silicon, aluminium and magnesium in geological matrices were determined by Neutron Activation Analysis based on k0-IAEA software. The optimum activation and delay times were found to be 5 min and 15-20 min respectively for the determination of Si via (29)Si (n,p) (29)Al reaction. The adopted irradiation scheme did not work for the determination of magnesium. Each sample was irradiated under a thermal neutron flux density of 5.0 × 10(11) ncm(-2)s(-1). Cadmium covered activation indicated that a permanent epithermal irradiation site for research reactors would be very useful for routine determination of silicon in environmental samples. PMID:23999324

  19. Neutron Activation Cross Sections for Br79, Br81, Rh103, In115, I127, and Ta181

    Microsoft Academic Search

    S. A. Cox

    1964-01-01

    Neutron activation cross sections for Br79, Br81, Rh103, In115, I127, and Ta181 have been measured in the incident neutron energy range from 130 to 1800 keV. The results agree rather well with other activation measurements. The activation cross sections are combined to form the total neutron-capture cross sections of the natural elements and compared with the capture gamma-ray data of

  20. The structure of the Gamow-Teller giant resonance and consequences for beta-delayed neutron spectra and element synthesis

    Microsoft Academic Search

    H. V. Klapdor

    1976-01-01

    Recent results in beta-delayed neutron emission are interpreted by structure of the Gamow-Teller giant resonance not included in the ``gross-theory'' of beta-decay. Inclusion of this structure of the beta-strength function is important for calculations of beta-decay half lives and production rates for heavy nuclides by astrophysical processes and thermonuclear explosions.

  1. Probing high areal-density cryogenic deuterium-tritium implosions using downscattered neutron spectra measured by the magnetic recoil

    E-print Network

    Probing high areal-density cryogenic deuterium-tritium implosions using downscattered neutron; published online 23 April 2010 For the first time high areal-density R cryogenic deuterium-tritium DT essential for understanding how the fuel is assembled and for guiding the cryogenic program

  2. SEAPLANE HULL BOTTOM NEUTRON ACTIVATION STUDY. Bi-Monthly Progress Report No. 3

    Microsoft Academic Search

    Zizza

    1958-01-01

    The period since the release of the second progress report on the ; Neutron Activation Study of Seapiane Huii Bottom Materials has been spent in ; carrying out experimental work at Brookhaven and in analysis of the data ; collected. A series of specimen irradiations were made and the specific ; radioisotopes that led to the total activity of a

  3. Metabolic activity of sodium, measured by neutron activation, in the hands of patients suffering from bone diseases: concise communication

    SciTech Connect

    Spinks, T.J.; Bewley, D.K.; Paolillo, M.; Vlotides, J.; Joplin, G.F.; Ranicar, A.S.O.

    1980-01-01

    Turnover of sodium in the human hand was studied by neutron activation. Patients suffering from various metabolic abnormalities affecting the skeleton, who were undergoing routine neutron activation for the measurement of calcium, were investigated along with a group of healthy volunteers. Neutron activation labels the sodium atoms simultaneously and with equal probability regardless of the turnover time of individual body compartments. The loss of sodium can be described either by a sum of two exponentials or by a single power function. Distinctions between patients and normal subjects were not apparent from the exponential model but were brought out by the power function. The exponent of time in the latter is a measure of clearance rate. The mean values of this parameter in (a) a group of patients suffering from acromegaly; (b) a group including Paget's disease, osteoporosis, Cushing's disease, and hyperparathyroidism; and (c) a group of healthy subjects, were found to be significantly different from each other.

  4. Analysis of Different Uncertainty Activation Cross Section Data Libraries for LWR, ADS and DEMO Neutron Spectr

    NASA Astrophysics Data System (ADS)

    Díez, C. J.; Cabellos, O.; Martínez, J. S.

    2012-05-01

    This work is aimed to present the main differences of nuclear data uncertainties among three different nuclear data libraries: EAF-2007, EAF-2010 and SCALE-6.0, under different neutron spectra: LWR, ADS and DEMO (fusion). To take into account the neutron spectrum, the uncertainty data are collapsed to onegroup. That is a simple way to see the differences among libraries for one application. Also, the neutron spectrum effect on different applications can be observed. These comparisons are presented only for (n,fission), (n,gamma) and (n,p) reactions, for the main transuranic isotopes (234,235,236,238U, 237Np, 238,239,240,241Pu, 241,242m,243Am, 242,243,244,245,246,247,248Cm, 249Bk, 249,250,251,252Cf). But also general comparisons among libraries are presented taking into account all included isotopes. In other works, target accuracies are presented for nuclear data uncertainties; here, these targets are compared with uncertainties on the above libraries. The main results of these comparisons are that EAF-2010 has reduced their uncertainties for many isotopes from EAF-2007 for (n,gamma) and (n,fission) but not for (n,p); SCALE-6.0 gives lower uncertainties for (n,fission) reactions for ADS and PWR applications, but gives higher uncertainties for (n,p) reactions in all applications. For the (n,gamma) reaction, the amount of isotopes which have higher uncertainties is quite similar to the amount of isotopes which have lower uncertainties when SCALE-6.0 and EAF-2010 are compared. When the effect of neutron spectra is analysed, the ADS neutron spectrum obtained the highest uncertainties for (n,gamma) and (n,fission) reactions of all libraries.

  5. Fission and activation of uranium by fusion-plasma neutrons

    NASA Technical Reports Server (NTRS)

    Lee, J. H.; Hohl, F.; Mcfarland, D. R.

    1978-01-01

    Fusion-fission hybrid reactors are discussed in terms of two main purposes: to breed fissile materials (Pu 233 and Th 233 from U 238 or Th 232) for use in low-reactivity breeders, and to produce tritium from lithium to refuel fusion plasma cores. Neutron flux generation is critical for both processes. Various methods for generating the flux are described, with attention to new geometries for multiple plasma focus arrays, e.g., hypocycloidal pinch and staged plasma focus devices. These methods are evaluated with reference to their applicability to D-D fusion reactors, which will ensure a virtually unlimited energy supply. Accurate observations of the neutron flux from such schemes are obtained by using different target materials in the plasma focus.

  6. Iodine-129 separation and determination by neutron activation analysis

    SciTech Connect

    Bate, L.C.; Stokely, J.R.

    1981-01-01

    A method is described for analysis of /sup 129/I in fission product mixtures originating from fuel reprocessing studies and low-level wastes. The method utilizes conventional iodine valence adjustment and solvent extraction techniques to chemically separate /sup 129/I from most fission products. The /sup 129/I is determined by neutron irradiation and measurement of the 12.4 h /sup 130/I produced by the neutron capture reaction. Special techniques were devised for neutron irradiation of /sup 129/I samples in the pneumatic tube irradiation facilities at the High Flux Isotope (HFIR) and Oak Ridge Research (ORR) Reactors. Chemically separated /sup 129/I is adsorbed on an anion exchange resin column made from an irradiation container. The loaded resin is then irradiated in either of the pneumatic facilities to produce /sup 130/I. Sensitivity of the analysis with the HFIR facility (flux: 5 x 10/sup 14/ n/cm/sup 2//sec) and a 100-second irradiation time is approximately 0.03 nanograms. Samples up to 250 ml in volume can be easily processed.

  7. Active Neutron and Gamma-Ray Instrumentation for In Situ Planetary Science Applications

    NASA Technical Reports Server (NTRS)

    Parsons, A.; Bodnarik, J.; Evans, L.; Floyd, A.; Lim, L.; McClanahan, T.; Namkung, M.; Nowicki, S.; Schweitzer, J.; Starr, R.; Trombka, J.

    2011-01-01

    We describe the development of an instrument capable of detailed in situ bulk geochemical analysis of the surface of planets, moons, asteroids, and comets. This instrument technology uses a pulsed neutron generator to excite the solid materials of a planet and measures the resulting neutron and gamma-ray emission with its detector system. These time-resolved neutron and gamma-ray data provide detailed information about the bulk elemental composition, chemical context, and density distribution of the soil within 50 cm of the surface. While active neutron scattering and neutron-induced gamma-ray techniques have been used extensively for terrestrial nuclear well logging applications, our goal is to apply these techniques to surface instruments for use on any solid solar system body. As described, experiments at NASA Goddard Space Flight Center use a prototype neutron-induced gamma-ray instrument and the resulting data presented show the promise of this technique for becoming a versatile, robust, workhorse technology for planetary science, and exploration of any of the solid bodies in the solar system. The detection of neutrons at the surface also provides useful information about the material. This paper focuses on the data provided by the gamma-ray detector.

  8. Medical applications of in vivo neutron inelastic scattering and neutron activation analysis: Technical similarities to detection of explosives and contraband

    NASA Astrophysics Data System (ADS)

    Kehayias, J. J.

    2001-07-01

    Nutritional status of patients can be evaluated by monitoring changes in elemental body composition. Fast neutron activation (for N and P) and neutron inelastic scattering (for C and O) are used in vivo to assess elements characteristic of specific body compartments. There are similarities between the body composition techniques and the detection of hidden explosives and narcotics. All samples have to be examined in depth and the ratio of elements provides a "signature" of the chemical of interest. The N/H and C/O ratios measure protein and fat content in the body. Similarly, a high C/O ratio is characteristic of narcotics and a low C/O together with a strong presence of N is a signature of some explosives. The available time for medical applications is about 20 min—compared to a few seconds for the detection of explosives—but the permitted radiation exposure is limited. In vivo neutron analysis is used to measure H, O, C, N, P, Na, Cl, and Ca for the study of the mechanisms of lean tissue depletion with aging and wasting diseases, and to investigate methods of preserving function and quality of life in the elderly.

  9. Side chain and flexibility contributions to the Raman optical activity spectra of a model cyclic hexapeptide.

    PubMed

    Hudecová, Jana; Kapitán, Josef; Baumruk, Vladimír; Hammer, Robert P; Keiderling, Timothy A; Bour, Petr

    2010-07-22

    A model peptide, cyclo-(Phe-d-Pro-Gly-Arg-Gly-Asp), with a distinct folded structure containing short beta-hairpin and beta-sheet patterns was studied by Raman and Raman optical activity (ROA) spectroscopies. Unlike for previously analyzed vibrational circular dichroism of the same compound (Chirality 2008, 20, 1104), the Raman spectrum is dominated by side chain contributions and is more sensitive to their geometry fluctuations. The spectra and molecular motion were analyzed with the aid of the density functional theory simulations combined with molecular dynamics (MD). The side chain geometry fluctuations were found to significantly contribute to the broadening of the spectral bands, while dynamics of the backbone is rather restricted. According to our MD results, the side chains do not move freely but largely oscillate around preferred conformations. Averaging of computed spectra for many structures derived from the MD trajectories provided better spectral profiles than did a fixed geometry. The Raman and ROA scattering is dominated by the more polarizable phenylalanine and proline groups, as could be verified both by the computations and by comparison to experiments with a model Phe-d-Pro dipeptide. Computational analyses suggest that the ROA spectrum mostly senses local side chain conformation, whereas a vibrational coupling between different side chains contributes less. The coupling is mostly mediated by the peptide backbone and is restricted to specific vibrational region. The ROA spectroscopic technique thus provides important local structural information that needs, however, to be extracted by multiscale (QM/MM) simulation techniques. PMID:20578775

  10. Signs of antimetastatic activity of palladium complexes of methylenediphosphonic acid in IR spectra

    NASA Astrophysics Data System (ADS)

    Tolstorozhev, G. B.; Skornyakov, I. V.; Pekhnio, V. I.; Kozachkova, A. N.; Sharykina, N. I.

    2012-07-01

    We have used Fourier transform IR spectroscopy methods to study normal mouse lung tissue and also after subcutaneous transplantation of a B-16 melanoma tumor in the tissue. We also studied tissues with B-16 melanoma after they were treated with coordination compounds based on palladium complexes of methylenediphosphonic acid. The IR spectra of the lung tissues with metastases in the region of the C = O stretching vibrations are different from the IR spectra of normal tissue. We identified spectroscopic signs of the presence of metastases in the lung. We show that when a cancerous tumor is treated with a preparation of palladium complexes of methylenediphosphonic acid, the spectroscopic signs of the presence of metastases in the lung are missing. After treatment with the optimal dose of this drug, the IR spectrum of the lung tissue in which multiple metastases were present before treatment corresponds to the spectrum of normal tissue. We have determined the efficacy of the antitumor activity of coordination compounds based on palladium complexes of methylenediphosphonic acid.

  11. A complete census of silicate features in the mid-infrared spectra of active galaxies

    E-print Network

    Hatziminaoglou, Evanthia; Feltre, Anna; Piñol-Ferrer, Nuria

    2015-01-01

    We present a comprehensive study of the silicate features at 9.7 and 18 micron of a sample of almost 800 active galactic nuclei (AGN) with available spectra from the Spitzer InfraRed Spectrograph (IRS). We measure the strength of the silicate feature at 9.7 micron, S9.7, before and after subtracting the host galaxy emission from the IRS spectra. The numbers of type 1 and 2 AGN with the feature in emission increase by 20 and 50%, respectively, once the host galaxy is removed, while 35% of objects with the feature originally in absorption exhibit it in even deeper absorption. The peak of S9.7, lambda_peak, has a bimodal distribution when the feature is in emission, with about 65% of the cases showing lambda_peak > 10.2 micron. Silicates can appear in emission in objects with mid-infrared (MIR) luminosity spanning over six orders of magnitude. The derived distributions of the strength of the silicate features at 9.7 and 18 micron provide a solid test bed for modeling the dust distribution in AGN. Clumpiness is n...

  12. Testing of regolith of celestial bolides with active neutron gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Vostrukhin, Andrey; Mitrofanov, Igor; Golovin, Dmitry; Litvak, Maxim; Sanin, Anton

    2015-04-01

    Current space instruments for studying planet's surface include gamma ray spectrometers that detect natural radioactive isotopes as well as gamma-rays induced in subsurface by galactic cosmic rays. When measuring from celestial body's surface, statistics and amount of detected elements can be dramatically increased with active methods, where soil exposed to artificial flux of particles. One good example is the Russian Dynamic Albedo of Neutron (DAN) instrument onboard Martian Science Laboratory mission (Curiosity rover) developed in 2005-2011. It is the first active neutron spectrometer flown to another planet as part of a landed mission to investigate subsurface water distribution and which has now successfully operated for more than two years on the Martian surface. Presentation describes a number of space instruments for different landers and rovers being developed in Russian Space Research Institute for studying Moon and Mars, as well as method of active neutron and gamma spectrometry overview.

  13. Measurement Of Hydrogen In Advanced Materials By Cold Neutron Prompt Gamma-ray Activation Analysis

    NASA Astrophysics Data System (ADS)

    Paul, Rick L.

    2006-05-01

    An instrument for cold neutron prompt gamma-ray activation analysis (PGAA), located at the NIST Center for Neutron Research (NCNR), has proven useful for the measurement of trace hydrogen in advanced materials. Samples are irradiated by a beam of neutrons extracted from the reactor core; gamma rays emitted upon neutron capture are measured by a high purity germanium detector. The detection limit for hydrogen is less than 10 mg/kg for most materials. PGAA has been used to study hydrogen in a wide variety of materials, including titanium alloys, RF superconducting niobium cavities, and semiconductor materials. The technique has also been used to measure hydrogen uptake by solid proton conductors and hydrogen storage materials. A future upgrade to the instrument will improve detection limits and applicability of the method.

  14. Properties of solar coronal active regions deduced from X-ray line spectra

    NASA Astrophysics Data System (ADS)

    McKenzie, D. L.

    1987-11-01

    Spectra from the SOLEX B RAP spectrometer have been used to analyze the temperature and density structure of over 100 nonflaring solar active regions. Density measurements that used the R ratio of O VII indicated that few regions have electron densities higher than ?3×109cm-3. In a few cases, flare-productive regions had measured densities approximately twice this high. Temperature-sensitive line ratios in the helium-like ions O VII, Ne IX, and Mg XI were used to decude the general properties of the differential emission-measure function B(T) for nonflaring regions. B(T) falls off with increasing temperature above a peak temperature that is almost always lower than Tm(O VII) = 1.8×106K.

  15. Monte Carlo Modelling of the Electron Spectra of 235U- and 239Pu Films, Irradiated by Thermal Neutrons, Due to All Possible Mechanisms Excluding b-Decay. Comparison With Experiment

    Microsoft Academic Search

    V. D. Rusova; V. A. Tarasova; D. A. Litvinova; S. V. Iaroshenkob

    2004-01-01

    The electron energy spectra, not connected to b-decay, of 235U- and\\u000a239Pu-films, irradiated by thermal neutrons, obtained by a Monte Carlo method\\u000ais presented in the given work. The modelling was performed with the help of a\\u000acomputer code MCNP4C (Monte Carlo Neutron Photon transport code system),\\u000aallowing to carry out the computer experiments on joint transport of neutrons,\\u000aphotons

  16. INTERMITTENCY AND MULTIFRACTALITY SPECTRA OF THE MAGNETIC FIELD IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Abramenko, Valentyna; Yurchyshyn, Vasyl [Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314 (United States)

    2010-10-10

    We present the results of a study of intermittency and multifractality of magnetic structures in solar active regions (ARs). Line-of-sight magnetograms for 214 ARs of different flare productivity observed at the center of the solar disk from 1997 January until 2006 December are utilized. Data from the Michelson Doppler Imager (MDI) instrument on board the Solar and Heliospheric Observatory operating in the high resolution mode, the Big Bear Solar Observatory digital magnetograph, and the Hinode SOT/SP instrument were used. Intermittency spectra were derived from high-order structure functions and flatness functions. The flatness function exponent is a measure of the degree of intermittency. We found that the flatness function exponent at scales below approximately 10 Mm is correlated with flare productivity (the correlation coefficient is -0.63). The Hinode data show that the intermittency regime is extended toward small scales (below 2 Mm) as compared to the MDI data. The spectra of multifractality, derived from the structure functions and flatness functions, are found to be broader for ARs of higher flare productivity as compared to those of low flare productivity. The magnetic structure of high-flaring ARs consists of a voluminous set of monofractals, and this set is much richer than that for low-flaring ARs. The results indicate the relevance of the multifractal organization of the photospheric magnetic fields to the flaring activity. The strong intermittency observed in complex and high-flaring ARs is a hint that we observe a photospheric imprint of enhanced sub-photospheric dynamics.

  17. Residual 152Eu and 60Co activities induced by neutrons from the Hiroshima atomic bomb

    SciTech Connect

    Shizuma, K.; Iwatani, K.; Hasai, H.; Hoshi, M.; Oka, T.; Morishima, H. (Hiroshima Univ. (Japan))

    1993-09-01

    Specific activities of 152Eu:Eu in stone samples exposed to the Hiroshima atomic bomb were determined for 70 samples up to a 1,500-m slant range from the epicenter. The specific activities of 60Co:Co were also determined for six samples near the Hiroshima hypocenter. First, the 152Eu data were investigated to find out the directional dependence of neutron activation. Directional anisotropy was not definite; however, there was an indication that the activation in the west-southwest was lower than in other directions. Second, measured 152Eu and 60Co radioactivity data were compared with activation calculations based on DS86 neutrons. It is clearly shown that the measured data are lower than the calculation near the hypocenter and vice versa at long distances beyond 1,000 m. The calculated-to-measured ratios of 152Eu are 1.6 at the hypocenter, 1.0 at approximately 900 m, and 0.05 at a 1,500-m slant range. Present results indicate that systematic errors exist in the DS86 neutrons concerning the source-term spectrum, neutron transport calculations in air, and/or activation measurements.

  18. Analysis of active neutron multiplicity data for Y-12 skull oxide samples

    SciTech Connect

    Krick, M.S.; Ensslin, N. [Los Alamos National Lab., NM (United States); Ceo, R.N.; May, P.K. [Oak Ridge Y-12 Plant, TN (United States)

    1996-09-01

    Previous work on active neutron multiplicity measurements and analyses is summarized. New active multiplicity measurements are described for samples of Y-12 skull oxide using an Active Well Coincidence Counter and MSR4 multiplicity electronics. Neutron multiplication values for the samples were determined from triples/doubles ratios. Neutron multiplication values were also obtained from Monte Carlo calculations using the MCNP code and the results compared with the experimental values. A calibration curve of AmLi source-sample coupling vs neutron multiplication was determined and used for active multiplicity assay of the skull oxides. The results are compared with those obtained from assay with the conventional calibration-curve technique, where the doubles rate is calibrated vs the {sup 235}U mass. The coupling-multiplication relationship determined for the skull oxides is compared with that determined earlier for pure high-enrichment uranium metal and pure uranium oxide. Conclusions are drawn about the application of active multiplicity techniques to uranium assay. Additional active multiplicity measurements and calculations are recommended.

  19. Determination of elements in National Bureau of Standards' geological Standard Reference Materials by neutron activation analysis

    SciTech Connect

    Graham, C.C.; Glascock, M.D.; Carni, J.J.; Vogt, J.R.; Spalding, T.G.

    1982-08-01

    Instrumental neutron activation analysis (INAA) and prompt gamma neutron activation analysis (PGNAA) have been used to determine elemental concentrations in two recently issued National Bureau of Standards (NBS) Standard Reference Materials (SRM's). The results obtained are in good agreement with the certified and information values reported by NBS for those elements in each material for which comparisons are available. Average concentrations of 35 elements in SRM 278 obsidian rock and 32 elements in SRM 688 basalt rock are reported for comparison with results that may be obtained by other laboratories.

  20. Large sample neutron activation analysis: a challenge in cultural heritage studies.

    PubMed

    Stamatelatos, Ion E; Tzika, Faidra

    2007-07-01

    Large sample neutron activation analysis compliments and significantly extends the analytical tools available for cultural heritage and authentication studies providing unique applications of non-destructive, multi-element analysis of materials that are too precious to damage for sampling purposes, representative sampling of heterogeneous materials or even analysis of whole objects. In this work, correction factors for neutron self-shielding, gamma-ray attenuation and volume distribution of the activity in large volume samples composed of iron and ceramic material were derived. Moreover, the effect of inhomogeneity on the accuracy of the technique was examined. PMID:17867535

  1. A search for iron emission lines in the Chandra X-ray spectra of neutron star low-mass X-ray binaries

    E-print Network

    E. M. Cackett; J. M. Miller; J. Homan; M. van der Klis; W. H. G. Lewin; M. Mendez; J. Raymond; D. Steeghs; R. Wijnands

    2008-09-18

    While iron emission lines are well studied in black hole systems, both in X-ray binaries and Active Galactic Nuclei, there has been less of a focus on these lines in neutron star low-mass X-ray binaries (LMXBs). However, recent observations with Suzaku and XMM-Newton have revealed broad asymmetric iron line profiles in 4 neutron star LMXBs, confirming an inner disk origin for these lines in neutron star systems. Here, we present a search for iron lines in 6 neutron star LMXBs. For each object we have simultaneous Chandra and RXTE observations at 2 separate epochs, allowing for both a high resolution spectrum, as well as broadband spectral coverage. Out of the six objects in the survey, we only find significant iron lines in two of the objects, GX 17+2 and GX 349+2. However, we cannot rule out that there are weak, broad lines present in the other sources. The equivalent width of the line in GX 17+2 is consistent between the 2 epochs, while in GX 349+2 the line equivalent width increases by a factor of ~3 between epochs as the source flux decreases by a factor of 1.3. This suggests that the disk is highly ionized, and the line is dominated by recombination emission. We find that there appears to be no specific locations in the long-term hardness-intensity diagrams where iron emission lines are formed, though more sources and further observations are required.

  2. Residual 152Eu and 60Co activities induced by neutrons from the Hiroshima atomic bomb

    Microsoft Academic Search

    Kiyoshi Shizuma; Kazuo Iwatani; Hiromi Hasai; Masaharu Hoshi; Takamitsu Oka; Hiroshige Morishima

    1993-01-01

    Specific activities of 152Eu:Eu in stone samples exposed to the Hiroshima atomic bomb were determined for 70 samples up to a 1,500-m slant range from the epicenter. The specific activities of 60Co:Co were also determined for six samples near the Hiroshima hypocenter. First, the 152Eu data were investigated to find out the directional dependence of neutron activation. Directional anisotropy was

  3. A bismuth activation counter for high sensitivity pulsed 14 MeV neutrons

    NASA Astrophysics Data System (ADS)

    Burns, E. J. T.; Thacher, P. D.; Hassig, G. J.; Decker, R. D.; Romero, J. A.; Barrett, K. P.

    2011-08-01

    We have built a fast neutron bismuth activation counter that measures activation counts from pulsed 14-MeV neutron generators for incident neutron fluences between 30 and 300 neutrons/cm2 at 15.2 cm (6 in.). The activation counter consists of a large bismuth germanate (BGO) detector surrounded by a bismuth metal shield in front of and concentric with the cylindrical detector housing. The 14 MeV neutrons activate the 2.6-millisecond (ms) isomer in the shield and the detector by the reaction 209Bi (n,2n?) 208mBi. The use of millisecond isomers and activation counting times minimizes the background from other activated materials and the environment. In addition to activation, the bismuth metal shields against other outside radiation sources. We have tested the bismuth activation counter, simultaneously, with two data acquisition systems (DASs) and both give similar results. The two-dimensional (2D) DAS and three dimensional (3D) DAS both consist of pulse height analysis (PHA) systems that can be used to discriminate against gamma radiations below 300 keV photon energy, so that the detector can be used strictly as a counter. If the counting time is restricted to less than 25 ms after the neutron pulse, there are less than 10 counts of background for single pulse operation in all our operational environments tested so far. High-fluence neutron generator operations are restricted by large dead times and pulse height saturation. When we operate our 3D DAS PHA system in list mode acquisition (LIST), real-time corrections to dead time or live time can be made on the scale of 1 ms time windows or dwell times. The live time correction is consistent with nonparalyzable models for dead time of 1.0±0.2 ?s for our 3D DAS and 1.5±0.3 ?s for our 2D DAS dominated by our fixed time width analog to digital converters (ADCs). With the same solid angle, we have shown that the bismuth activation counter has a factor of 4 increase in sensitivity over our lead activation counter, because of higher counts and negligible backgrounds.

  4. Analytical capability of an explosives detection by a prompt gamma-ray neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Im, Hee-Jung; Cho, Hyun-Je; Song, Byoung Chul; Park, Yong Joon; Chung, Yong-Sam; Kim, Won-Ho

    2006-10-01

    Neutron-induced prompt gamma-ray analysis method was evaluated for the detection of explosives by measuring the H, C(C/H), and N(N/H) concentrations of samples at a research nuclear reactor. The hydrogen concentration was measured from the calibration curves obtained from various samples which contained hydrogen, and the detection limit for the determination of hydrogen in the samples was estimated. Standard reference materials (NIST SRMs) were used as analytical controls. The ?-spectra obtained here will be directly used for further studies as a training set for a pattern recognition to develop suitable discriminant classes with which explosives can be distinguished from innocuous materials.

  5. Measurement of neutron spectra for determining dose equivalent rates at the Texas A&M University Nuclear Science Center

    E-print Network

    Sanza, Bruce Jerome

    1986-01-01

    . Nuclear Regulatory Commission, Washington, DC. NUREG/CR-3400. Griffith, R. V. , J. CD Pisher, C. A. Harder, 1977, "Development of a Combined Etch Track ? Albedo Dosimeter", Hazards 0 1 ~P* R 9 N . 54, L L' L 6, Livermore, CA. UCRL-50007-77 ? 1. Gr... Lawrence Livermore Lab, Livermore, CA. UCRL-52415. Stinchcomb, T. G. , T. B. Borak, 1983, "Neutron guality Parameters Versus Energy Below 4 MeV from Microdosimetric Calculations", Radiation Research, 93:1 ? 18. Tommasino, L. , K. G ~ Harrison, 1985...

  6. NEUTRON ACTIVATION CROSS SECTION FOR Br⁷⁹, Br⁸¹, Rh¹°³, In¹¹⁵, AND I¹²⁷

    Microsoft Academic Search

    Cox

    1963-01-01

    Thin disks of the elements were irradiated with neutrons from the ; Li(p,n) reaction, and the activation cross sections were determined by measuring ; the activity duc to fast neutron capture relative to that for thermal neutron ; capture. The results are graphically displayed and are compared with existing ; activation measurements. The activation measurements are combined to form the

  7. Composite spectra Paper 13: 93 Leonis, a chromospherically-active binary

    NASA Astrophysics Data System (ADS)

    Griffin, R. E. M.; Griffin, R. F.

    2004-05-01

    We isolate the spectrum of the secondary component of the composite-binary system 93 Leonis by spectrum subtraction, classify it, and measure the mass ratio of the system. An accurate visual orbit and a well-determined parallax provide reliable measurements of orbital inclination and distance, enabling us to determine precisely the individual masses and other stellar parameters. The primary star is of type ~G7 III, and the secondary is a rapidly rotating star of type A7 IV. Our photographic spectra at 10 Å mm-1 are invaluable for accurate spectral classification in such cases. By combining 23 measurements of the secondary's velocity with 102 of the primary's and deriving a double-lined orbit, we determine the mass ratio (q=M1/M2) of 93 Leo to be 1.09 +/- 0.04. The same value is derived by cross-correlating high-dispersion spectra of 93 Leo B extracted from opposite nodal phases. That value of q is consonant with previous research, but its precision is considerably improved. We show that random errors arising from the cross-correlation of broad, weak features constitute a natural limit to that precision. The derived masses of M1= 2.2 Msolar, M2= 2.0 Msolar for the giant and dwarf, respectively, constrain the choice of models for fitting evolutionary tracks in the (logTeff, logL) plane. The giant is almost certainly on its first ascent of the red giant branch, and the dwarf has evolved significantly from the main sequence. The stars fit an isochrone for log(age) = 8.95, about 0.9 Gyr. Metallicity near to solar is suggested by the close correspondence between the component spectra and those of the respective solar-abundance standards. The primary in 93 Leo displays a marked level of chromospheric activity. By combining our high-dispersion spectra we are able to isolate emission in the Ca II K line. The chromospheric material has a small infall velocity, giving rise to a disc-averaged redshift of about 4 km s-1, and an unchanging velocity profile which can be attributed to a large number of small, active events like prominences across the surface. While we can say that there was no perceptible change in the emission strength over an interval of 4 months, we have not made systematic observations to monitor its long-term stability. We contrast the components of 93 Leo with those of ? Equ, whose analysis was the subject of Paper 11 in this series. The primary components are very similar, but the two secondary components are extremely different in nature: whereas 93 Leo B is a broad-lined, apparently normal A star, the secondary of ? Equ is a sharp-lined Am star of type ~kA3hA4mA9. We question why that should be, and recommend that a greater emphasis be placed on extracting accurate stellar parameters from the components of spectroscopic binaries as a means towards a better understanding of the vagaries of stellar evolution. 93 Leo has a 9-mag visual companion which appears to be a physical member of the system and to be a single-lined spectroscopic binary with a period of the order of a century.

  8. Anharmonic effects in IR, Raman, and Raman optical activity spectra of alanine and proline zwitterions.

    PubMed

    Danecek, Petr; Kapitán, Josef; Baumruk, Vladimír; Bednárová, Lucie; Kopecký, Vladimír; Bour, Petr

    2007-06-14

    The difference spectroscopy of the Raman optical activity (ROA) provides extended information about molecular structure. However, interpretation of the spectra is based on complex and often inaccurate simulations. Previously, the authors attempted to make the calculations more robust by including the solvent and exploring the role of molecular flexibility for alanine and proline zwitterions. In the current study, they analyze the IR, Raman, and ROA spectra of these molecules with the emphasis on the force field modeling. Vibrational harmonic frequencies obtained with 25 ab initio methods are compared to experimental band positions. The role of anharmonic terms in the potential and intensity tensors is also systematically explored using the vibrational self-consistent field, vibrational configuration interaction (VCI), and degeneracy-corrected perturbation calculations. The harmonic approach appeared satisfactory for most of the lower-wavelength (200-1800 cm(-1)) vibrations. Modern generalized gradient approximation and hybrid density functionals, such as the common B3LYP method, provided a very good statistical agreement with the experiment. Although the inclusion of the anharmonic corrections still did not lead to complete agreement between the simulations and the experiment, occasional enhancements were achieved across the entire region of wave numbers. Not only the transitional frequencies of the C-H stretching modes were significantly improved but also Raman and ROA spectral profiles including N-H and C-H lower-frequency bending modes were more realistic after application of the VCI correction. A limited Boltzmann averaging for the lowest-frequency modes that could not be included directly in the anharmonic calculus provided a realistic inhomogeneous band broadening. The anharmonic parts of the intensity tensors (second dipole and polarizability derivatives) were found less important for the entire spectral profiles than the force field anharmonicities (third and fourth energy derivatives), except for a few weak combination bands which were dominated by the anharmonic tensor contributions. PMID:17581069

  9. Phase coupling analysis of gastric pressure activity via wavelet packet based diagonal slice spectra.

    PubMed

    Yan, Rongguo; Yan, Guozheng; Zhang, Wenqiang; Zhang, Genfu

    2006-09-01

    We propose a new analysis method to detect quadratic phase coupling (QPC) behavior of human gastric interdigestive pressure activity that has been acquired by a telemetric capsule-like mini-robot. The method is referred to as diagonal slice spectra. They are the Fourier transforms of the diagonal slices of the triple correlations, and can actually detect the phase coupling and coupled components respectively by expanding the real process into the complex counterpart through Hilbert transform. In order to learn more about the QPC structure in a certain frequency band that we are mostly interested in and obtain a higher frequency resolution, the method, named the wavelet packet based diagonal slice spectrum, is introduced. It shows that the nonlinear QPC behavior occurs during gastric contractions (phase II), whereas no distinct phase coupling occurs during gastric motor quiescence (phase I). It is the nonlinear cell-to-cell coupling mechanisms, existence of fast and slow waves and their interactions that nonlinear QPC structure of the gastric pressure activity occurs. PMID:16930765

  10. Chromospheric activity and lithium line variations in the spectra of the spotted star LQ Hydrae

    NASA Astrophysics Data System (ADS)

    Flores Soriano, M.; Strassmeier, K. G.; Weber, M.

    2015-03-01

    Context. Although the relationship between lithium abundance in stars and their magnetic activity is commonly accepted, it is still unclear how the different phenomena related to it can increase the amount of Li, reduce its depletion, or be a source of bias for the measurements. Aims: We study the rotational modulation of chromospheric and photospheric parameters of the young, active, single K2 dwarf LQ Hya and their connection with the variability of the Li i 6708 Å line. Methods: A total of 199 high-resolution STELLA spectra and quasi-simultaneous photometry were used to compute effective temperature, gravity, and chromospheric activity indicators such as H? and H? emission, Balmer decrement, and chromospheric electron density, as a function of the rotational phase. The variation of the Li i 6708 Å line was characterized in terms of equivalent width, abundance, and of 6Li/7Li isotopic ratio in the form of line shifts. Results: Photospheric and chromospheric parameters show clear rotational modulation. Effective temperatures and continuum variations reveal a higher concentration of cool spots on the side of the star on which we also detect stronger chromospheric activity. Increased electron densities and the modulation of the He i D3 line suggest that the source of this activity can be a combination of plages and repeated low-intensity flares. The Li line and other temperature-sensitive lines are clearly enhanced by the spots located on the most active side of the star. Li abundances calculated taking into account the temperature variations simultaneously show, although with high dispersion, a small overabundance of this element that correlates well with the surface magnetic activity. In addition, the Li line center is more intensely redshifted than in the other hemisphere, which might be interpreted as a weak enrichment of 6Li. Based on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC, and the Vienna-Potsdam Automatic Photoelectric Telescopes at Fairborn Observatory in Arizona, operated by AIP.The numerical results of the spectral analysis are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/575/A57

  11. Applications of Prompt Gamma Ray Neutron Activation Analysis: Detection of Illicit Materials

    Microsoft Academic Search

    Hee-Jung Im; Kyuseok Song

    2009-01-01

    Prompt gamma ray neutron activation analysis (PGNAA) is an efficient nondestructive multi-elemental detection technique for samples such as metals, coal (mineral), cement, and radioactive materials as well as for explosives, chemical warfare agents, various narcotics, land mines, etc. The technique can be used in the laboratory or for on-site analysis for various samples. In addition, the PGNAA technique in elemental

  12. LOFT experimental measurements uncertainty analyses. Volume XX. Fluid-velocity measurement using pulsed-neutron activation

    SciTech Connect

    Lassahn, G.D.; Taylor, D.J.N.

    1982-08-01

    Analyses of uncertainty components inherent in pulsed-neutron-activation (PNA) measurements in general and the Loss-of-Fluid-Test (LOFT) system in particular are given. Due to the LOFT system's unique conditions, previously-used techniques were modified to make the volocity measurement. These methods render a useful, cost-effective measurement with an estimated uncertainty of 11% of reading.

  13. Neutron activation cross sections for Ti isotopes at 14.8 MeV

    Microsoft Academic Search

    I. Ribansky; S. Gmuca

    1983-01-01

    Neutron activation cross sections for Ti isotopes at 14.8 MeV were measured using Ge(Li) gamma -ray spectroscopy. The linear least-squares method was used to resolve the interfering reactions of neighbouring isotopes. The results obtained are discussed in detail and are compared with pre-equilibrium, equilibrium and semi-empirical calculations.

  14. Recommendations on the choice of effective thresholds and neutron activation cross-sections

    Microsoft Academic Search

    E. A. Kramer-Ageev; V. S. Troshin; G. A. Borisov; R. D. Vasil'ev; N. B. Galiev; E. I. Grigor'ev; V. P. Yaryna

    1973-01-01

    Translated from Izmer. Tekh.; 16: No. 1, 61(Jan 1973). A system of ; equations for regenerating the neutron spectrum from data from a group of ; activation detectors is given and discussed. Effective thresholds, effective ; cross sections, and the relative percentage error of the effective cross section ; for 23 threshold reactions are tabulated. (WHK);

  15. Neutron activation cross section for Ni isotopes at 14·8 MeV

    Microsoft Academic Search

    I. Ribanský; J. Kristiak; L. Stoeva; C. Panteleev

    1985-01-01

    Neutron activation cross sections for Ni isotopes were measured using Ge(Li)?-ray spectroscopy of the reaction products. The linear least-squares method was used to resolve the interfering reactions. The results obtained are compared with recent experimental and evaluated data, statistical model and semiempirical calculations.

  16. Recommended nuclear data for use in the k 0 standardization of neutron activation analysis

    Microsoft Academic Search

    Frans De Corte; András Simonits

    2003-01-01

    k0 factors (composite nuclear constants) for use in the k0 standardization of reactor neutron activation analysis were experimentally measured with great care in several laboratories. The recommended values thus obtained for the relevant gamma rays of 144 analytically interesting radionuclides are tabulated, together with evaluated values for their associated parameters such as resonance integral to thermal cross-section ratios and effective

  17. Determination of impurities in nuclear fuel element components by neutron activation analysis

    Microsoft Academic Search

    R. J. Rosenberg; R. Zilliacus

    1993-01-01

    Neutron activation analysis methods for the determination of impurities in zirconium cladding material and uranium oxide are described. Detection limits for the elements Al, Cd, Cr, Co, Cu, Hf, Fe, Mn, Ni, W and U in zirconium are below that required by the ASTM B 352-79 standard. The method has been tested on the NIST SRM 360a Zircaloy-2 from which

  18. ANALYSIS OF PM10 IN KUALA TERENGGANU BY INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS

    Microsoft Academic Search

    Norhayati Mohd Tahir; Poh Seng Chee; Suhaimi Hamzah; Khalik Hj Wood; Shamsiah Abd; Wee Boon Siong; Suhaimi Elias

    Instrumental neutron activation analysis was used for the determination of trace elements in airborne particulate matter (PM10) for air pollution monitoring. For the collection of air samples, the PM10 high volume sampler unit and Whatman 41 cellulose filter papers were employed. Samples were collected at 13 selected sampling sites covering areas in the city center, inner and outer city of

  19. Neutron activation analysis of fluid inclusions for copper, manganese, and zinc

    USGS Publications Warehouse

    Czamanske, G.K.; Roedder, E.; Burns, F.C.

    1963-01-01

    Microgram quantities of copper, manganese, and zinc, corresponding to concentrations greater than 100 parts per million, were found in milligram quantities of primary inclusion fluid extracted from samples of quartz and fluorite from two types of ore deposits. The results indicate that neutron activation is a useful analytical method for studying the content of heavy metal in fluid inclusions.

  20. Gamma exposure rates due to neutron activation of soil: site of Hood detonation, Operation Plumbbob

    Microsoft Academic Search

    J. A. Auxier; W. F. Ohnesorge

    1980-01-01

    This paper is the result of some recent discussions of exposure rates within the first few hours of the Hood detonation of the Plumbbob series due to neutron activation of soil. We estimated the exposure rates from 1\\/2 to 3 h after the detonation from ground zero to 1000 yards from ground zero. The area was assumed to be uncontaminated

  1. Application of the anti-Compton detector in neutron activation analysis techniques

    NASA Astrophysics Data System (ADS)

    Gierlik, M.; Borsuk, S.; Guzik, Z.; Iwanowska, J.; Ka?mierczak, ?.; Korolczuk, S.; Koz?owski, T.; Krakowski, T.; Marcinkowski, R.; Swiderski, L.; Szeptycka, M.; Szewi?ski, J.; Urban, A.

    2015-07-01

    In this work we report about performance of the cylindrical 3 in.×3 in. LaBr3 scintillation detector assembled with a BGO guard detector. This setup was optimized for the identification of explosive materials by means of fast neutron activation analysis.

  2. Minimum activation martensitic alloys for surface disposal after exposure to neutron flux

    DOEpatents

    Lechtenberg, Thomas (San Diego, CA)

    1985-01-01

    Steel alloys for long-term exposure to neutron flux have a martensitic microstructure and contain chromium, carbon, tungsten, vanadium and preferably titanium. Activation of the steel is held to within acceptable limits for eventual surface disposal by stringently controlling the impurity levels of Ni, Mo, Cu, N, Co, Nb, Al and Mn.

  3. Comparison standards for neutron activation analysis on a base of phenol-formaldehyde resin

    Microsoft Academic Search

    M. A. Kolomi'tsev; T. S. Ambardanashvili; V. Yu. Dundua

    1974-01-01

    The possibility of preparation of comparison standards for activation analysis on a base of phenol-formaldehyde polymer has\\u000a been shown. This polymer contains only a small amount of neutron-sensitive impurities. The suggested standards may be prepared\\u000a in large amounts under laboratory conditions.

  4. Single-crystal neutron diffraction of bio-active small molecules

    NASA Astrophysics Data System (ADS)

    Wilson, C. C.; Shankland, N.; Florence, A. J.; Frampton, C. S.

    1997-02-01

    The structures of three bio-active small molecules, acetylcholine bromide, creatine monohydrate and paracetamol, are described. Together with a brief account of the molecular geometry and hydrogen bonding, the temperature variation of the methyl group thermal parameters are specifically discussed. The room temperature structure of paracetamol from neutron diffraction data is reported for the first time.

  5. Pottery analysis using PIXE, neutron activation, scanning electron microscopy and X-ray fluorescence techniques

    Microsoft Academic Search

    I. Brissaud; A. Houdayer; C. JEI-IANNO; A. Sabir

    1985-01-01

    Potsherds were analyzed chemically by four different techniques. Results are compared for many elements. The effect of temper appears as a problem because of the inhomogeneity of the bulk. PIXE and neutron activation are powerful and complementary methods to obtain element concentrations for proveniance studies. Also scanning electron microscopy and the electron microprobe are very useful to detect and analyze

  6. Probing Planetary Bodies for Subsurface Volatiles: GEANT4 Models of Gamma Ray, Fast, Epithermal, and Thermal Neutron Response to Active Neutron Illumination

    NASA Astrophysics Data System (ADS)

    Chin, G.; Sagdeev, R.; Su, J. J.; Murray, J.

    2014-12-01

    Using an active source of neutrons as an in situ probe of a planetary body has proven to be a powerful tool to extract information about the presence, abundance, and location of subsurface volatiles without the need for drilling. The Dynamic Albedo of Neutrons (DAN) instrument on Curiosity is an example of such an instrument and is designed to detect the location and abundance of hydrogen within the top 50 cm of the Martian surface. DAN works by sending a pulse of neutrons towards the ground beneath the rover and detecting the reflected neutrons. The intensity and time of arrival of the reflection depends on the proportion of water, while the time the pulse takes to reach the detector is a function of the depth at which the water is located. Similar instruments can also be effective probes at the polar-regions of the Moon or on asteroids as a way of detecting sequestered volatiles. We present the results of GEANT4 particle simulation models of gamma ray, fast, epithermal, and thermal neutron responses to active neutron illumination. The results are parameterized by hydrogen abundance, stratification and depth of volatile layers, versus the distribution of neutron and gamma ray energy reflections. Models will be presented to approximate Martian, lunar, and asteroid environments and would be useful tools to assess utility for future NASA exploration missions to these types of planetary bodies.

  7. Neutron activation cross-sections in rare earths and heavier nuclei

    Microsoft Academic Search

    K. Siddappa; M. Sriramachandra Murty; J. Rama Rao

    1973-01-01

    Summary  Radiative neutron capture cross-sections for the isotopes138Ba,140Ce,142Ce,146Nd,148Nd,160Gd,165Ho,180Hf,181Ta,190Os,197Au and202Hg have been measured at the neutron energy (23±5) keV by means of the activation method and 4?-geometry gamma-counting technique. In 9 cases for each of which there is a single previous report of the cross-section, the\\u000a present work serves as a check on the previous value. In the remaining cases the present

  8. Innovative high pressure gas MEM's based neutron detector for ICF and active SNM detection.

    SciTech Connect

    Martin, Shawn Bryan; Derzon, Mark Steven; Renzi, Ronald F.; Chandler, Gordon Andrew

    2007-12-01

    An innovative helium3 high pressure gas detection system, made possible by utilizing Sandia's expertise in Micro-electrical Mechanical fluidic systems, is proposed which appears to have many beneficial performance characteristics with regards to making these neutron measurements in the high bremsstrahlung and electrical noise environments found in High Energy Density Physics experiments and especially on the very high noise environment generated on the fast pulsed power experiments performed here at Sandia. This same system may dramatically improve active WMD and contraband detection as well when employed with ultrafast (10-50 ns) pulsed neutron sources.

  9. NEUTRON ACTIVATION CROSS-SECTIONS OF ⁹⁶Ru AND ¹°²Ru

    Microsoft Academic Search

    S. Katcoff; D. C. Williams

    1958-01-01

    Measurements of the activities of 2.88 day Ru⁹⁷ and 39.7 day Ru\\/; sup 103\\/ from (n, gamma ) reactions on natural Ru showed that the thermal neutron ; activation cross-sections of Ru⁹⁶ and Ru¹°² are 0.210 and 1.50 barns, ; respectively. The intensities of 2.70 day Ru\\/ 196\\/ in gold monitors were used as ; standards. That Ru¹⁹⁶ has at

  10. Thermal neutron activation cross sections and resonance integrals of 94Zr and 96Zr

    Microsoft Academic Search

    D. C. Santry; R. D. Werner

    1973-01-01

    The activation method was used to determine thermal neutron activation ; cross sections, sigma \\/sub o\\/, and resonance integrals, RI. Values obtained ; were sigma \\/sub o\\/ = 47.5 plus or minus 2.4 mb, RI = 218 plus or minus 10 mb ; for ⁹⁴Zr an d sigma \\/sub o\\/ = 22.9 plus or minus 1.0 mb, RI = 5.20

  11. Recent upgrade of the in vivo neutron activation facility at Brookhaven National Laboratory

    SciTech Connect

    Ma, R.; Dilmanian, F.A..; Rarback, H.; Meron, M.; Kamen, Y.; Yasumura, S.; Weber, D.A. [Brookhaven National Lab., Upton, NY (United States); Stamatelatos, I.E. [Ioannina Univ. (Greece). Dept. of Medical Physics; Lidofsky, L.J. [Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Nuclear Engineering; Pierson, R.N. Jr. [Saint Luke`s-Roosevelt Body Composition Unit, New York, NY (United States)

    1993-10-01

    The in vivo neutron activation facility at Brookhaven National Laboratory consists of a delayed- and a prompt-gamma neutron activation (DGNA and PGNA) system and an inelastic neutron scattering (INS) system. The total body contents of several basic elements, including potassium, calcium, chlorine, sodium, and phosphorus are measured at the DGNA system; total body carbon is measured at the INS system; and the nitrogen-tohydrogen ratio is measured at the PGNA system. Based on the elemental composition, body compartments, such as total body fat and total body protein can be computed with additional independently measured parameters, such as total body water, body size, and body weight. Information on elemental and compartmental body composition obtained through neutron activation analysis is useful, if not essential, for research on growth, malnutrition, aging diseases, such as osteoporosis and acquired immunodeficiency syndrome in which the progression of the illness is closely related to changes in major body compartments, such as bone, adipose tissue, and muscle. The DGNA system has been modified and upgraded several times since it was first built. Recently, all three systems underwent major upgrades. This upgrading and some preliminary studies carried out with the modified facilities are reported here.

  12. Gamma/neutron analysis for SNM signatures at high-data rates(greater than 107 cps) for single-pulse active interrogation

    SciTech Connect

    Forman L.; Dioszegi, I.; Salwen, C.

    2011-04-26

    We are developing a high data gamma/neutron spectrometer suitable for active interrogation of special nuclear materials (SNM) activated by a single burst from an intense source. We have tested the system at Naval Research Laboratory's (NRL) Mercury pulsed-power facility at distances approaching 10 meters from a depleted uranium (DU) target. We have found that the gamma-ray field in the target room 'disappears' 10 milliseconds after the x-ray flash, and that gamma ray spectroscopy will then be dominated by isomeric states/beta decay of fission products. When a polyethylene moderator is added to the DU target, a time-dependent signature of the DU is produced by thermalized neutrons. We observe this signature in gamma-spectra measured consecutively in the 0.1-1.0 ms time range. These spectra contain the Compton edge line (2.2 MeV) from capture in hydrogen, and a continuous high energy gamma-spectrum from capture or fission in minority constituents of the DU.

  13. The possible mechanism of the formation of emission clouds radiating broad lines in the spectra of active galactic nuclei

    Microsoft Academic Search

    A. S. Zentsova

    1991-01-01

    The present study proves the hypothesis that the formation of emission clouds radiating the permitted lines in the spectra of active galaxies takes place in the outer parts of an accretion disk around a massive black hole. These parts of the disk become self-gravitating and may disintegrate into fragments. The nonlinear effects in the disk must provoke the slow drift

  14. Importance of neutron energy distribution in borehole activation analysis in relatively dry, low-porosity rocks

    USGS Publications Warehouse

    Senftle, F.E.; Moxham, R.M.; Tanner, A.B.; Philbin, P.W.; Boynton, G.R.; Wager, R.E.

    1977-01-01

    To evaluate the importance of variations in the neutron energy distribution in borehole activation analysis, capture gamma-ray measurements were made in relatively dry, low-porosity gabbro of the Duluth Complex. Although sections of over a meter of solid rock were encountered in the borehole, there was significant fracturing with interstitial water leading to a substantial variation of water with depth in the borehole. The linear-correlation coefficients calculated for the peak intensities of several elements compared to the chemical core analyses were generally poor throughout the depth investigated. The data suggest and arguments are given which indicate that the variation of the thermal-to-intermediate-to-fast neutron flux density as a function of borehole depth is a serious source of error and is a major cause of the changes observed in the capture gamma-ray peak intensities. These variations in neutron energy may also cause a shift in the observed capture gamma-ray energy.

  15. Studies on the synthesis, spectra, catalytic and antibacterial activities of binuclear ruthenium(II) complexes

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, P.; Sathyadevi, P.; Deepa, K.; Dharmaraj, N.

    2010-09-01

    A new series of stable binuclear ruthenium(II) carbonyl complexes of the general formula [{RuX(CO)(EPh 3) 2} 2L] (where X = H or Cl; E = P or As and L = dibasic tetradentate diacetyl resorcinol (H 2-DAR)) have been synthesised by reacting ruthenium(II) starting complexes [RuHX(CO)(EPh 3) 3] (where X = H or Cl; E = P or As) and 4,6-diacetylresorcinol (H 2-DAR) ligand in benzene medium. The structure of the new binuclear ruthenium(II) carbonyl complexes was established using elemental analysis, spectra (FT-IR, UV-vis and 1H NMR), electrochemical and thermal studies. In these reactions, the 4,6-diacetylresorcinol (H 2-DAR) ligand behaves as a binegative tetradentate chelating ligand coordinating through O,O atoms of both the carbonyl and phenolic C-O groups by replacing a molecule of PPh 3/AsPh 3 and a hydride ion from the starting complexes. Further, all these complexes were also employed as new catalysts for the oxidation of primary and secondary alcohols in the presence of N-methylmorpholine-N-oxide (NMO) as a more viable co-oxidant. The free ligand and their metal complexes have also been screened for their antibacterial activity against the growth of gram +ve and gram -ve bacterial cultures.

  16. Studies on the synthesis, spectra, catalytic and antibacterial activities of binuclear ruthenium(II) complexes.

    PubMed

    Krishnamoorthy, P; Sathyadevi, P; Deepa, K; Dharmaraj, N

    2010-09-15

    A new series of stable binuclear ruthenium(II) carbonyl complexes of the general formula [{RuX(CO)(EPh(3))(2)}(2)L] (where X=H or Cl; E=P or As and L=dibasic tetradentate diacetyl resorcinol (H(2)-DAR)) have been synthesised by reacting ruthenium(II) starting complexes [RuHX(CO)(EPh(3))(3)] (where X=H or Cl; E=P or As) and 4,6-diacetylresorcinol (H(2)-DAR) ligand in benzene medium. The structure of the new binuclear ruthenium(II) carbonyl complexes was established using elemental analysis, spectra (FT-IR, UV-vis and (1)H NMR), electrochemical and thermal studies. In these reactions, the 4,6-diacetylresorcinol (H(2)-DAR) ligand behaves as a binegative tetradentate chelating ligand coordinating through O,O atoms of both the carbonyl and phenolic C-O groups by replacing a molecule of PPh(3)/AsPh(3) and a hydride ion from the starting complexes. Further, all these complexes were also employed as new catalysts for the oxidation of primary and secondary alcohols in the presence of N-methylmorpholine-N-oxide (NMO) as a more viable co-oxidant. The free ligand and their metal complexes have also been screened for their antibacterial activity against the growth of gram +ve and gram -ve bacterial cultures. PMID:20538510

  17. Supernova Neutrino Light Curves and Spectra for Various Progenitor Stars: From Core Collapse to Proto-neutron Star Cooling

    NASA Astrophysics Data System (ADS)

    Nakazato, Ken'ichiro; Sumiyoshi, Kohsuke; Suzuki, Hideyuki; Totani, Tomonori; Umeda, Hideyuki; Yamada, Shoichi

    2013-03-01

    We present a new series of supernova neutrino light curves and spectra calculated by numerical simulations for a variety of progenitor stellar masses (13-50 M ?) and metallicities (Z = 0.02 and 0.004), which would be useful for a broad range of supernova neutrino studies, e.g., simulations of future neutrino burst detection by underground detectors or theoretical predictions for the relic supernova neutrino background. To follow the evolution from the onset of collapse to 20 s after the core bounce, we combine the results of neutrino-radiation hydrodynamic simulations for the early phase and quasi-static evolutionary calculations of neutrino diffusion for the late phase, with different values of shock revival time as a parameter that should depend on the still unknown explosion mechanism. We describe the calculation methods and basic results, including the dependence on progenitor models and the shock revival time. The neutrino data are publicly available electronically.

  18. Gamma exposure rates due to neutron activation of soil: site of Hood detonation, Operation Plumbbob

    SciTech Connect

    Auxier, J.A.; Ohnesorge, W.F.

    1980-06-01

    This paper is the result of some recent discussions of exposure rates within the first few hours of the Hood detonation of the Plumbbob series due to neutron activation of soil. We estimated the exposure rates from 1/2 to 3 h after the detonation from ground zero to 1000 yards from ground zero. The area was assumed to be uncontaminated by fallout. Soil samples from the area of the Nevada Test Site at which the Hood device was detonated were sent to ORNL by Dr. John Malik of Los Alamos and by Mr. Gordon Jacks of the Nevada Test Site. These samples were irradiated at the DOSAR facility and the resulting activity analyzed. Calculations of exposure rates were then made based on the analyzed activity and the measured thermal neutron fluences at DOSAR and at the Hood Site.

  19. Correlation of irradiation creep data obtained in fast and thermal neutron spectra with displacement cross-sections

    NASA Astrophysics Data System (ADS)

    Foster, J. P.; Boltax, A.

    1980-04-01

    Irradiation creep data are available for 20% cold-worked M316 stainless steel, 20% cold-worked FV548 stainless steel, solution-annealed 304 stainless steel and aged Nimonic PE16 for the same heats of material and state of stress tested in thermal and fast neutron reactors. The transient and steady state irradiation creep coefficients were calculated using spectrum-averaged displacement cross-section dose units (i.e. displacements per atom). The transient irradiation creep coefficients appear to be subject to considerable scatter. The steady state irradiation creep coefficients were found to be a consistent factor of 2.5 larger in thermal than fast reactors. These results are in excellent agreement with the fast reactor dose rate dependence of the steady state irradiation creep rate observed by Lewthwaite and Mosedale. However, the dose rate effect-directly depends on the displacement cross-section, which is a calculated dependent parameter. The available information suggests that the displacement cross-section function uncertainty is the major effect responsible for the 2.5 factor in irradiation creep coefficients.

  20. Recent activities for ?-decay half-lives and ?-delayed neutron emission of very neutron-rich isotopes

    SciTech Connect

    Dillmann, Iris [TRIUMF, Vancouver BC, V6T 2A3, Canada and GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Abriola, Daniel [Laboratorio Tandar, Comisión Nacional de Energía Atómica, B1650KINA, San Martín, Buenos Aires (Argentina); Singh, Balraj [Department of Physics and Astronomy, McMaster University, Hamilton ON, L8S 4M1 (Canada)

    2014-05-02

    Beta-delayed neutron (?n) emitters play an important, two-fold role in the stellar nucleosynthesis of heavy elements in the 'rapid neutron-capture process' (r process). On one hand they lead to a detour of the material ?-decaying back to stability. On the other hand, the released neutrons increase the neutron-to-seed ratio, and are re-captured during the freeze-out phase and thus influence the final solar r-abundance curve. A large fraction of the isotopes inside the r-process reaction path are not yet experimentally accessible and are located in the (experimental) 'Terra Incognita'. With the next generation of fragmentation and ISOL facilities presently being built or already in operation, one of the main motivation of all projects is the investigation of these very neutron-rich isotopes. A short overview of one of the planned programs to measure ?n-emitters at the limits of the presently know isotopes, the BRIKEN campaign (Beta delayed neutron emission measurements at RIKEN) will be given. Presently, about 600 ?-delayed one-neutron emitters are accessible, but only for a third of them experimental data are available. Reaching more neutron-rich isotopes means also that multiple neutron-emission becomes the dominant decay mechanism. About 460 ?-delayed two-, three-or four-neutron emitters are identified up to now but for only 30 of them experimental data about the neutron branching ratios are available, most of them in the light mass region below A=30. The International Atomic and Energy Agency (IAEA) has identified the urgency and picked up this topic recently in a 'Coordinated Research Project' on a 'Reference Database for Beta-Delayed Neutron Emission Data'. This project will review, compile, and evaluate the existing data for neutron-branching ratios and half-lives of ?-delayed neutron emitters and help to ensure a reliable database for the future discoveries of new isotopes and help to constrain astrophysical and theoretical models.

  1. ACTL: evaluated neutron activation cross section library-evaluation techniques and reaction index. [Tables, 10¹° to 20 MeV

    Microsoft Academic Search

    M. A. Gardner; R. J. Howerton

    1978-01-01

    A library of evaluated neutron-induced activation cross sections (ACTL) was compiled. The library covers incident neutron energies from 10¹° to 20 MeV. General descriptions of the evaluation methods and an index to the evaluated cross sections are presented. 21 references.

  2. On the use of prompt gamma-ray neutron activation analysis for determining phase amounts in multiphase flow

    Microsoft Academic Search

    Jiaxin Wang; Fusheng Li; Robin P. Gardner

    2008-01-01

    Prompt gamma-ray neutron activation analysis (PGNAA) is considered for the measurement of the in situ multiphase flow amounts of oil, gas, water and salt in a deep sea oil well. PGNAA has the advantages for this application that: (1) useful characteristic prompt gamma rays are produced by neutron interactions with almost all elements, (2) it is a rapid non-destructive measurement

  3. Cold neutron PGAA facility at Budapest

    Microsoft Academic Search

    Zs. Révay; T. Belgya; Zs. Kasztovszky; J. L. Weil; G. L. Molnár

    2004-01-01

    The new cold neutron prompt gamma activation analysis (PGAA) facility provides improved capabilities for routine prompt gamma analysis and for the investigation of radiative neutron capture. The versatile beam chopper makes possible time-of-flight measurements and the acquisition of prompt and decay spectra simultaneously. The chopped beam PGAA technique combines the advantages of the in-beam measurement and the greater simplicity of

  4. Spatially Resolved Spectra of the "Teacup" Active Galactic Nucleus: Tracing the History of a Dying Quasar

    NASA Astrophysics Data System (ADS)

    Gagne, J. P.; Crenshaw, D. M.; Kraemer, S. B.; Schmitt, H. R.; Keel, W. C.; Rafter, S.; Fischer, T. C.; Bennert, V. N.; Schawinski, K.

    2014-09-01

    The Sloan Digital Sky Survey (SDSS) Galaxy Zoo project has revealed a number of spectacular galaxies possessing extended emission-line regions (EELRs), the most famous being Hanny's Voorwerp galaxy. We present another EELR object discovered in the SDSS endeavor: the Teacup active galactic nucleus (AGN). Nicknamed for its EELR, which has a "handle"-like structure protruding 15 kpc into the northeast quadrant of the galaxy. We analyze the physical conditions of this galaxy with long-slit, ground-based spectroscopy from the Lowell, Lick, and KPNO observatories. With the Lowell 1.8 m Perkin's telescope we took multiple observations at different offset positions, allowing us to recover spatially resolved spectra across the galaxy. Line diagnostics indicate the ionized gas is photoionized primarily by the AGN. Additionally we are able to derive the hydrogen density from the [S II] ?6716/?6731 ratio. We generated two-component photoionization models for each spatially resolved Lowell spectrum. These models allow us to calculate the AGN bolometric luminosity seen by the gas at different radii from the nuclear center of the Teacup. Our results show a drop in bolometric luminosity by more than two orders of magnitude from the EELR to the nucleus, suggesting that the AGN has decreased in luminosity by this amount in a continuous fashion over 46,000 yr, supporting the case for a dying AGN in this galaxy independent of any IR based evidence. We demonstrate that spatially resolved photoionization modeling could be applied to EELRs to investigate long timescale variability.

  5. Neutron Activation Cross Sections for Mercury Isotopes at 14.1 MeV

    Microsoft Academic Search

    J. K. Temperley

    1969-01-01

    Fast-neutron activation cross sections for the mercury isotopes have been measured relative to the 56Fe(n,p)56Mn cross section. Enriched and natural-isotopic-abundance samples of Hg compounds were irradiated with 14.1+\\/-0.5-MeV neutrons. The activities produced were determined by observing the gamma radiation with a Ge(Li) detector. The following cross sections (in millibarns) were determined: 196Hg(n,2n)195mHg, 1060+\\/-70 198Hg(n,2n)197mHg, 900+\\/-70 198Hg(n,2n)197gHg, 940+\\/-100 198Hg(n,p)198Au, 4.7+\\/-0.3 199Hg(n,p)199Au,

  6. Neutron spectra, recoil momenta and PI/sup 0/ production cross sections for reactions induced by 10-100 MeV/nucleon heavy ions

    SciTech Connect

    Blann, M.

    1985-08-01

    The Boltzmann master equation model has been applied to the question of precompound nucleon de-excitation of reactions induced by 10 to 100 MeV/nucleon (c.m.) heavy ions. Test systems of /sup 16/O + /sup 60/Ni and /sup 27/Al + /sup 86/Kr were selected. Experimental neutron spectra in coincidence with evaporation residue and fission fragments from the /sup 20/Ne + /sup 165/Ho system (due to Holub, et al.) were reproduced quite well by the master equation with exciton numbers between 20 and 23. Results show major fractions of the excitation and up to 35 nucleons removed during the coalescence-equilibration period. The linear momentum transfer predicted by the master equation is shown to be in good agreement with a broad range of data. Extension of the master equation to predict sub-threshold PI/sup 0/ production cross sections is shown to give satisfactory agreement with a large number of experimental results. 48 refs., 8 figs., 7 tabs.

  7. Restricted active space calculations of L-edge X-ray absorption spectra: From molecular orbitals to multiplet states

    NASA Astrophysics Data System (ADS)

    Pinjari, Rahul V.; Delcey, Mickaël G.; Guo, Meiyuan; Odelius, Michael; Lundberg, Marcus

    2014-09-01

    The metal L-edge (2p ? 3d) X-ray absorption spectra are affected by a number of different interactions: electron-electron repulsion, spin-orbit coupling, and charge transfer between metal and ligands, which makes the simulation of spectra challenging. The core restricted active space (RAS) method is an accurate and flexible approach that can be used to calculate X-ray spectra of a wide range of medium-sized systems without any symmetry constraints. Here, the applicability of the method is tested in detail by simulating three ferric (3d5) model systems with well-known electronic structure, viz., atomic Fe3+, high-spin [FeCl6]3- with ligand donor bonding, and low-spin [Fe(CN)6]3- that also has metal backbonding. For these systems, the performance of the core RAS method, which does not require any system-dependent parameters, is comparable to that of the commonly used semi-empirical charge-transfer multiplet model. It handles orbitally degenerate ground states, accurately describes metal-ligand interactions, and includes both single and multiple excitations. The results are sensitive to the choice of orbitals in the active space and this sensitivity can be used to assign spectral features. A method has also been developed to analyze the calculated X-ray spectra using a chemically intuitive molecular orbital picture.

  8. Restricted active space calculations of L-edge X-ray absorption spectra: From molecular orbitals to multiplet states

    SciTech Connect

    Pinjari, Rahul V.; Delcey, Mickaël G.; Guo, Meiyuan; Lundberg, Marcus, E-mail: marcus.lundberg@kemi.uu.se [Department of Chemistry - Ångström Laboratory, Uppsala University, SE-751 20 Uppsala (Sweden); Odelius, Michael [Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm (Sweden)

    2014-09-28

    The metal L-edge (2p ? 3d) X-ray absorption spectra are affected by a number of different interactions: electron-electron repulsion, spin-orbit coupling, and charge transfer between metal and ligands, which makes the simulation of spectra challenging. The core restricted active space (RAS) method is an accurate and flexible approach that can be used to calculate X-ray spectra of a wide range of medium-sized systems without any symmetry constraints. Here, the applicability of the method is tested in detail by simulating three ferric (3d{sup 5}) model systems with well-known electronic structure, viz., atomic Fe{sup 3+}, high-spin [FeCl{sub 6}]{sup 3?} with ligand donor bonding, and low-spin [Fe(CN){sub 6}]{sup 3?} that also has metal backbonding. For these systems, the performance of the core RAS method, which does not require any system-dependent parameters, is comparable to that of the commonly used semi-empirical charge-transfer multiplet model. It handles orbitally degenerate ground states, accurately describes metal-ligand interactions, and includes both single and multiple excitations. The results are sensitive to the choice of orbitals in the active space and this sensitivity can be used to assign spectral features. A method has also been developed to analyze the calculated X-ray spectra using a chemically intuitive molecular orbital picture.

  9. Neutron activation cross sections at 14.4 MeV for Kr and Xe isotopes

    Microsoft Academic Search

    E. Kondaiah; N. Ranakumar; R. W. Fink

    1968-01-01

    Quinol-clathrates of Kr and Xe were used as solid target powders for neutron activation and cross sections for 16 (n, 2n), 7 (n, p), and one (n, alpha) reactions at 14.4+\\/-0.3 MeV have been measured; of these, 23 cross sections are reported for the first time. Work supported in part by the U.S. Atomic Energy Commission.

  10. 14. 6MeV neutron activation cross sections for the xenon isotopes. [(n,2n)

    Microsoft Academic Search

    R. A. Sigg; P. K. Kuroda

    1976-01-01

    Activation cross sections for 14 (n,2n) and 5 (n,p) reactions on xenon isotopes have been determined with 14.6-MeV neutrons using sodium perxenate and Ge(Li) gamma-ray spectroscopy. The values obtained are compared to the one earlier set of measurements on the xenon isotopes and to theoretical empirical values. The ¹²⁸Xe(n,p)¹²⁸I cross section is reported for the first time.

  11. Half-Life of Pd109 and Neutron Activation Cross Section of Pd102

    Microsoft Academic Search

    W. Wayne Meinke

    1953-01-01

    The half-life of Pd109 has been determined to be 13.6+\\/-0.1 hours by careful decay measurement on a chemically purified fraction of metallic palladium irradiated in a nuclear reactor. From the same irradiation the activation cross section of Pd102 was found to be 4.8 barns for pile neutrons. This cross section value is based on the literature value (corrected for the

  12. Measurement of rare earths elements in Kakul phosphorite deposits of Pakistan using instrumental neutron activation analysis

    Microsoft Academic Search

    Sabiha-Javied; S. Waheed; N. Siddique; R. Shakoor; M. Tufail

    2010-01-01

    The rare earth elements (REEs) content of Kakul phosphate rock (PR) from different localities of the main Hazara deposits\\u000a of Pakistan were determined using instrumental neutron activation analysis (INAA). 25 phosphorite samples were collected from\\u000a different phosphorite sites and 6 samples representing different batches from the crushing plant near Kakul Mine. Concentrations\\u000a of seven REEs (Ce, Eu, La, Lu, Sm,

  13. Reproducibility of neutron activated Sm153 in tablets intended for human volunteer studies

    Microsoft Academic Search

    C. H. Yeong; P. E. Blackshaw; K. H. Ng; B. J. J. Abdullah; M. Blaauw; R. J. Dansereau; A. C. Perkins

    Neutron activation of non-radioactive Sm-152 to Sm-153 offers a valuable method of radiolabeling for the in vivo study of the behavior of oral dosage formulations. In particular this methodology allows the manufacture of a pharmaceutical\\u000a formulation without the need for radioactive laboratory facilities. During manufacturing a small amount of Sm-152 is added\\u000a to the formulation. This is then irradiated with

  14. Survey of trace elements in coals and coal-related materials by neutron activation analysis

    USGS Publications Warehouse

    Ruch, R.R.; Cahill, R.A.; Frost, J.K.; Camp, L.R.; Gluskoter, H.J.

    1977-01-01

    Utilizing primarily instrumental neutron activation analysis (INAA) and other analytical methods as many as 61 elements were quantitatively surveyed in 170 U.S. whole coals, 70 washed coals, and 40 bench samples. Data on areal and vertical distributions in various regions were obtained along with extensive information on the mode of occurrence of various elements in the coal matrix itself. ?? 1977 Akade??miai Kiado??.

  15. k o -measurements and related nuclear data compilation for (n, ?) reactor neutron activation analysis

    Microsoft Academic Search

    A. Simonits; L. Moens; F. De Corte; A. De Wispelaere; A. Elek; J. Hoste

    1980-01-01

    ko-factors of 35 isotopes used in reactor neutron activation analysis were measured with a high degree of accuracy (1–2%). To\\u000a minimize systematic errors, measurements were carried out using different reactor types, irradiation conditions (18 s\\/?e), Ge(Li) detectors, sample detector geometry, etc. Analyst-oriented tabulations including all necessary nuclear data, “best\\u000a values”, as well as recommended ko-values are given to facilitate analytical

  16. A well-tested procedure for instrumental neutron activation analysis of silicate rocks and minerals

    Microsoft Academic Search

    J. W. Jacobs; R. L. Korotev; D. P. Blanchard; L. A. Haskin

    1977-01-01

    Procedures for instrumental neutron activation analysis (INAA) have been developed and used on more than a thousand small\\u000a samples of terrestrial and lunar silicate rocks and minerals for determination of Co, Cr, Fe, Hf, Na, Ni, Sc, Ta, Th, and\\u000a the rare earths La, Ce, Sm, Eu, Tb, Yb, and Lu. Precision has been determined by repeated analysis of Knippa

  17. Determination of selected trace elements in human head hair by neutron activation analysis

    E-print Network

    Courson, Leonard Austin

    1981-01-01

    . No requirement was made that hair which had been bleached, dyed or otherwise chemically treated be eliminated from the sample collection effort, since treated hair is a common feature of the population. After an individual sample was collected, it was sealed...DETERMINATION OF SELECTED TRACE ELFMENTS IN HUMAN HEAD HAIR BY NEUTRON ACTIVATION ANALYSIS A Thesis by LEONARD AUSl IN COURSDN Submitted to the Graduate College of Texas ABM University in partial ful fillment of the requirements...

  18. Neutron activation analysis for reference determination of the implantation dose of cobalt ions

    SciTech Connect

    Garten, R.P.H. [Max-Planck-Institut fuer Metallforschung, Dortmund (Germany); Bubert, H. [Institut fuer Spektrochemie und angewandte Spektrokopie, Dortmund (Germany); Palmetshofer, L. [Johannes-Kepler-Universitaet, Linz (Australia)

    1992-05-15

    The authors prepared depth profilling reference materials by cobalt ion implantation at an ion energy of 300 keV into n-type silicon. The implanted Co dose was then determined by instrumental neutron activation analysis (INAA) giving an analytical dynamic range of almost 5 decades and uncertainty of 1.5%. This form of analysis allows sources of error (beam spreading, misalignment) to be corrected. 70 refs., 3 tabs.

  19. Determination of selected trace elements in human head hair by neutron activation analysis 

    E-print Network

    Courson, Leonard Austin

    1981-01-01

    of Magnesium in Hair Distribution Histogram of Manganese in Hair Distribution Histogram of Sodium in Hair Distribution Histogram of Strontium in Hair Distribution Histogram of Titanium in Hair Distribution Histogram of Vanadium in Hair Distribution... 26 27 28 29 30 22 Distribution Histogram of Strontium in Hair by Sex 31 23 Distribution Histogram of Titanium in Hair by Sex 32 24 Distribution Histogram of Vanadium in Hair by Sex 33 INTRODUCTION )Measurements using neutron activation...

  20. Neutron activation analysis of modern pottery: Insights for archaeological provenance research

    SciTech Connect

    Neff, H. [Univ. of Missouri, Columbia, MO (United States); Arnold, D.E. [Wheaton College, IL (United States); Benco, N.L. [George Washington Univ., Washington, DC (United States); Thieme, M.S. [Vanderbilt Univ., Nashville, TN (United States)

    1996-12-31

    Neutron activation analysis has been employed to characterize ceramics and raw material samples from modern pottery-making communities. The original study focused on several villages in the central highlands of Guatemala. More recently, NAA data have been collected from communities in the Valley of Oaxaca, Mexico, the northern Yucatan Peninsula, and northern Morocco. The results from all four studies can now be combined to yield a comparative perspective on paste preparation effects in archaeological provenance research.

  1. Determination of trace impurities in nickel-based alloy using neutron activation analysis

    Microsoft Academic Search

    J. H. Zaidi; S. Waheed; S. Ahmed

    1999-01-01

    A radiochemical neutron activation analysis procedure has been applied to investigate 40 major, minor, and trace impurities\\u000a in nickel-based alloy. The extensive use of these alloys in the electronic industry, telecommunications, manufacturing of\\u000a aircraft engine turbine blades and chemical equipments desires for their precise characterization. The concentration of nickel\\u000a in the nickel-based alloy was found to be 56.8%, whereas Fe,

  2. Prompt gamma ray neutron activation analysis of cadmium in municipal solid waste

    E-print Network

    Dendahl, Katherine Hoge

    1991-01-01

    (Franklin Associates 1989). Discards of this source are expected to increase because the demand for nickel-cadmium batteries has grown replacing other types of batteries used in household appliances. Table 3 illustrates some additional sources of Table...). This can be achieved by; 1) shielding, especially of the detector materials to prevent activation and radiation damage of the crystal, 2) additional moderation of the neutron sources, and 3) sample volume and density changes to determine optimal size...

  3. Determination of extractable organohalogens in the atmosphere by instrumental neutron activation analysis

    Microsoft Academic Search

    D. Xu; Q. Tian; Z. Chai

    2006-01-01

    Summary  Air samples were collected at a downtown site in Beijing from January to July 2004 and analyzed by instrumental neutron activation\\u000a analysis (INAA) combined with organic solvent extraction method for the concentrations and distributions of extractable organohalogens\\u000a (EOX), including extractable organochlorinated (EOCl), organobrominated (EOBr) and organoiodinated compounds (EOI). The concentrations\\u000a of EOX were increasing in the order of EOCl >>

  4. Instrumental neutron activation analysis of extractable organohalogens in the Antarctic Weddell seal ( Leptonychotes weddelli )

    Microsoft Academic Search

    M. Kawano; J. Falandysz; T. Wakimoto

    2007-01-01

    Instrumental neutron activation analysis (INAA) was performed for measurement of extractable organohalogens (EOX) in blubber\\u000a samples of Weddell seals (Leptonychotes weddelli) from Antarctica. EOX were detected in all the analyzed samples. The concentration order of EOX was: extractable organochlorine\\u000a (EOCl)>extractable organobromine (EOBr)>extractable organoiodine (EOI). Their levels increased gradually with aging as with\\u000a other man-made persistent organic pollutants (POPs) such as

  5. Facility for Ground Tests with Active Neutron Instrumentation for the Planetary Science Missions

    NASA Astrophysics Data System (ADS)

    Litvak, Maxim; Jun, Insoo; Kozyrev, Alexander; Mitrofanov, Igor; Sanin, Anton; Shvetsov, Valery; Starr, Richard; Timoshenko, Gennady

    2015-04-01

    To conduct a feasibility study of active neutron and gamma spectrometers a special radiation test facility has been developed and built at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. It has total area of about 62 m2 and with height from floor to roof up to 3.5 m. To provide measurements with prototypes of space instruments developed for the nuclear planetology applications and to test capabilities of such instruments we have designed and constructed special soil targets similar to planetary material with known elemental composition, appropriate geometry and layered structure. Here we also present results of first experimental work performed with a spare flight model of the DAN/MSL instrument selected as a flight prototype of an active neutron spectrometer applicable for the future landed missions to various solid solar system bodies. In our experiment we have tested the capability of neutron activation methods to detect thin layers of water/water ice lying on top of planetary dry regolith or buried within a dry regolith at different depths.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Neutron activation analysis, gamma ray spectrometry and radiation environment monitoring instrument concept: GEORAD

    NASA Astrophysics Data System (ADS)

    Ambrosi, R. M.; Talboys, D. L.; Sims, M. R.; Bannister, N. P.; Makarewicz, M.; Stevenson, T.; Hutchinson, I. B.; Watterson, J. I. W.; Lanza, R. C.; Richter, L.; Mills, A.; Fraser, G. W.

    2005-02-01

    Geological processes on Earth can be related to those that may have occurred in past epochs on Mars, if analytical methods used on Earth can be operated remotely on the surface of the Red Planet. Nuclear analytical techniques commonly used in terrestrial geology are neutron activation analysis (NAA) and gamma-ray spectroscopy (GRS), which determine the elemental composition, elemental concentration and stratigraphical distribution of water in rocks and soils. We describe a detector concept called GEORAD (GEOlogical and RADiation environment package) for the proposed ExoMars rover within the ESA's Aurora Programme for the exploration of the Solar System. GEORAD consists of a compact neutron source for the NAA of rocks and soils and a GRS. The GRS has a dual role since it can be used for natural radioactivity studies and NAA. A fully depleted silicon detector coupled to neutron sensitive converters measures the solar particle and neutron flux interacting with the Martian surface. We describe how the GEORAD detector suite could contribute to the geological and biological characterisation of Mars both for the detection of extinct or extant life and to evaluate potential hazards facing future manned missions. We show how GEORAD measurements complement the astrobiological objectives of the Aurora programme.

  8. Calculated neutron-activation cross sections for E\\/sub n\\/ \\/le\\/ 100 MeV for a range of accelerator materials

    Microsoft Academic Search

    M. Bozoian; E. D. Arthur; R. T. Perry; W. B. Wilson; P. G. Young

    1988-01-01

    Activation problems associated with particle accelerators are commonly dominated by reactions of secondary neutrons produced in reactions of beam particles with accelerator or beam stop materials. Measured values of neutron-activation cross sections above a few MeV are sparse. Calculations with the GNASH code have been made for neutrons incident on all stable nuclides of a range of elements common to

  9. Cosmogenic-neutron activation of TeO2 and implications for neutrinoless double-beta decay experiments

    E-print Network

    Barbara S. Wang; Eric B. Norman; Nicholas D. Scielzo; Alan R. Smith; Keenan J. Thomas; Stephen A. Wender

    2015-03-06

    Flux-averaged cross sections for cosmogenic-neutron activation of natural tellurium were measured using a neutron beam containing neutrons of kinetic energies up to $\\sim$800 MeV, and having an energy spectrum similar to that of cosmic-ray neutrons at sea-level. Analysis of the radioisotopes produced reveals that 110mAg will be a dominant contributor to the cosmogenic-activation background in experiments searching for neutrinoless double-beta decay of 130Te, such as CUORE and SNO+. An estimate of the cosmogenic-activation background in the CUORE experiment has been obtained using the results of this measurement and cross-section measurements of proton activation of tellurium. Additionally, the measured cross sections in this work are also compared with results from semi-empirical cross-section calculations.

  10. Cosmogenic-neutron activation of TeO2 and implications for neutrinoless double-beta decay experiments

    E-print Network

    Wang, Barbara S; Scielzo, Nicholas D; Smith, Alan R; Thomas, Keenan J; Wender, Stephen A

    2015-01-01

    Flux-averaged cross sections for cosmogenic-neutron activation of natural tellurium were measured using a neutron beam containing neutrons of kinetic energies up to $\\sim$800 MeV, and having an energy spectrum similar to that of cosmic-ray neutrons at sea-level. Analysis of the radioisotopes produced reveals that 110mAg will be a dominant contributor to the cosmogenic-activation background in experiments searching for neutrinoless double-beta decay of 130Te, such as CUORE and SNO+. An estimate of the cosmogenic-activation background in the CUORE experiment has been obtained using the results of this measurement and cross-section measurements of proton activation of tellurium. Additionally, the measured cross sections in this work are also compared with results from semi-empirical cross-section calculations.

  11. Library of flux-calibrated echelle spectra of southern late-type dwarfs with different activity levels

    Microsoft Academic Search

    C. Cincunegui; P. J. D. Mauas

    2004-01-01

    We present Echelle spectra of 91 late-type dwarfs, of spectral types from F to M and of different levels of chromospheric activity, obtained with the 2.15 m telescope of the CASLEO Observatory located in the Argentinean Andes. Our observations range from 3890 to 6690 Å, at a spectral resolution from 0.141 to 0.249 Å per pixel (R=lambda\\/delta lambda ≈ 26

  12. Development of a prompt-gamma, neutron-activation analysis facility at the Texas A&M University Nuclear Science Center 

    E-print Network

    Inyang, Otu Effiong

    2009-05-15

    A prompt-gamma, neutron-activation analysis facility earlier developed at the Nuclear Science Center of Texas A&M University could not be used successfully to analyze geologic samples due to high detection background, low neutron fluence rate...

  13. Neutron activation cross sections in some barium isotopes at 14.2 MeV

    Microsoft Academic Search

    N. Lakshmana Das; C. V. Srinivasa Rao; B. V. Thirumala Rao; J. Rama Rao

    1980-01-01

    Activation cross sections were measured for the reactions 136Ba(n,2n)135mBa, 138Ba(n,p)138Cs and 138Ba(n, alpha )135m,gXe at an incident neutron energy of 14.2+or-0.2 MeV using the mixed powder technique. A high-resolution Ge(Li) detector was used to measure the induced gamma-ray activities. The cross sections were compared with both experimental and theoretical values reported in the literature.

  14. Copper activation deuterium-tritium neutron yield measurements at the National Ignition Facility.

    PubMed

    Cooper, G W; Ruiz, C L; Leeper, R J; Chandler, G A; Hahn, K D; Nelson, A J; Torres, J A; Smelser, R M; McWatters, B R; Bleuel, D L; Yeamans, C B; Knittel, K M; Casey, D T; Frenje, J A; Gatu Johnson, M; Petrasso, R D; Styron, J D

    2012-10-01

    A DT neutron yield diagnostic based on the reactions, (63)Cu(n,2n)(62)Cu(?(+)) and (65)Cu(n,2n)( 64) Cu(?(+)), has been fielded at the National Ignition Facility (NIF). The induced copper activity is measured using a NaI ?-? coincidence system. Uncertainties in the 14-MeV DT yield measurements are on the order of 7% to 8%. In addition to measuring yield, the ratio of activities induced in two, well-separated copper samples are used to measure the relative anisotropy of the fuel ?R to uncertainties as low as 5%. PMID:23126920

  15. [Results of measuring neutrons doses and energy spectra inside Russian segment of the International Space Station in experiment "Matryoshka-R" using bubble detectors during the ISS-24-34 missions].

    PubMed

    Khulapko, S V; Liagushin, V I; Arkhangel'ski?, V V; Shurshakov, V A; Smith, M; Ing, H; Machrafi, R; Nikolaev, I V

    2014-01-01

    The paper presents the results of calculating the equivalent dose from and energy spectrum of neutrons in the right-hand crewquarters in module Zvezda of the ISS Russian segment. Dose measurements were made in the period between July, 2010 and November, 2012 (ISS Missions 24-34) by research equipment including the bubble dosimeter as part of experiment "Matryoshka-R". Neutron energy spectra in the crewquarters are in good agreement with what has been calculated for the ISS USOS and, earlier, for the MIR orbital station. The neutron dose rate has been found to amount to 196 +/- 23 microSv/d on Zvezda panel-443 (crewquarters) and 179 +/- 16 microSv/d on the "Shielding shutter" surface in the crewquarters. PMID:25089327

  16. Inorganic ion exchangers for the removal of scandium and rare earth elements in neutron activation analysis of geological samples. [Neutron reactions

    Microsoft Academic Search

    K. Akilimali; B. Lumu; W. Mwamba

    1979-01-01

    Sorption properties of inorganic ion exchangers have been investigated for use in radiochemical separation of elements in geological samples subjected to neutron activation analysis. Samples were allowed to decay for two weeks, dissolved in hydrofluoric acid, and saturated boric acid was added to dissolve any fluoride complexes. Samples were placed onto the COX column and eluted with nitric acid. Retained

  17. TLD pairs, as thermal neutron detectors in neutron multisphere spectrometry

    Microsoft Academic Search

    Héctor René Vega-Carrillo

    2002-01-01

    Pairs of thermoluminescence dosimeters, TLD600 and TLD700, have been used as a thermal neutron detector in a multisphere neutron spectrometer. The neutron spectra from a bare 252Cf and a D2O moderated 252Cf sources were measured with the spectrometer with thermoluminescence dosimeters and with a 6LiI(Eu) scintillator. With the neutron spectra the total flux, average neutron energy, dose and equivalent dose

  18. Neutron-activation study of figurines, pottery, and workshop materials from the Athenian Agora, Greece. [Neutron reactions; France, Israel, Cyprus

    SciTech Connect

    Fillieres, D.; Harbottle, G.; Sayre, E.V.

    1983-01-01

    Ceramic specimens from the excavations of the Agora of ancient Athens, Greece, including material from factories, i.e., trial firing pieces, pottery and figurine wasters, datable to the Protogeometric, Subgeometric, and Classical Periods, and stylistically related figurines and pottery were analyzed by neutron activation. The factory material from the three distinct chronological periods separated respectively into three significantly different compositional groups, indicating either that separate sources of clay were used during each of these periods or that some other significant changes in the traditions of fabrication had occurred. Many of the figurines and sherds analyzed coincided in composition with one of these three groups and therefore were shown to be consistent with the output of Athenian workshops. Some specimens of Corinthian style formed a separate compositional group as did some other specimens that agreed in composition with a clay from Aegina. Comparison of these results with previous analyses on file in the Brookhaven Data Bank revealed a number of specimens that corresponded both in style and composition to the Agora material. Most significant was a sizable amount of Classical Greek pottery excavated in southern France, in Israel, and in Cyprus that conformed in composition to the Attic Classical Group. 6 figures, 2 tables.

  19. Measurements of fast ions and their interactions with MHD activity using neutron emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Hellesen, C.; Gatu Johnson, M.; Andersson Sundén, E.; Conroy, S.; Ericsson, G.; Eriksson, J.; Gorini, G.; Johnson, T.; Kiptily, V. G.; Pinches, S. D.; Sharapov, S. E.; Sjöstrand, H.; Nocente, M.; Tardocchi, M.; Weiszflog, M.; EFDA contributors, JET

    2010-08-01

    Ion cyclotron radio frequency (ICRF) heating can produce fast ion populations with energies reaching up to several megaelectronvolts. Here, we present unique measurements of fast ion distributions from an experiment with 3rd harmonic ICRF heating on deuterium beams using neutron emission spectroscopy (NES). From the experiment, very high DD neutron rates were observed, using only modest external heating powers. This was attributed to acceleration of deuterium beam ions to energies up to about 2-3 MeV, where the DD reactivity is on a par with that of the DT reaction. The high neutron rates allowed for observations of changes in the fast deuterium energy distribution on a time scale of 50 ms. Clear correlations were seen between fast deuterium ions in different energy ranges and magnetohydrodynamic activities, such as monster sawteeth and toroidal Alfven eigen modes (TAE). Specifically, NES data showed that the number of deuterons in the region between 1 and 1.5 MeV were decaying significantly during strong TAE activity, while ions with lower energies around 500 keV were not affected. This was attributed to resonances with the TAE modes.

  20. Neutron activation determination of iridium, gold, platinum, and silver in geologic samples

    USGS Publications Warehouse

    Millard, H.T., Jr.

    1987-01-01

    Low-level methods for the determination of iridium and other noble metals have become increasingly important in recent years due to interest in locating abundance anomalies associated with the Cretaceous and Tertiary (K-T) boundary. Typical iridium anomalies are in the range of 1 to 100 ??g/kg (ppb). Thus methods with detection limits near 0.1 ??g/kg should be adequate to detect K-T boundary anomalies. Radiochemical neutron activation analysis methods continue to be required although instrumental neutron activation analysis techniques employing elaborate gamma-counters are under development. In the procedure developed in this study samples irradiated in the epithermal neutron facility of the U. S. Geological Survey TRIGA Reactor (Denver, Colorado) are treated with a mini-fire assay technique. The iridium, gold, and silver are collected in a 1-gram metallic lead button. Primary contaminants at this stage are arsenic and antimony. These can be removed by heating the button with a mixture of sodium perioxide and sodium hydroxide. The resulting 0.2-gram lead bead is counted in a Compton suppression spectrometer. Carrier yields are determined by reirradiation of the lead beads. This procedure has been applied to the U.S.G.S. Standard Rock PCC-1 and samples from K-T boundary sites in the Western Interior of North America. ?? 1987 Akade??miai Kiado??.

  1. Rainbow-Like Spectra with a CD: An Active-Learning Exercise

    ERIC Educational Resources Information Center

    Planinsic, G.

    2008-01-01

    Rainbow-like spectra, produced by reflexive diffraction of white light on a CD, offer a spectacular visual effect as well as an excellent classroom opportunity for students to learn how physics works. In this paper we show that building a coherent qualitative explanation can be a challenging task that requires students to combine gained knowledge…

  2. Standardization of NIRR-1 irradiation and counting facilities for instrumental neutron activation analysis.

    PubMed

    Jonah, S A; Umar, I M; Oladipo, M O A; Balogun, G I; Adeyemo, D J

    2006-07-01

    The first nuclear reactor in Nigeria, the Nigeria Research Reactor-1 (NIRR-1), is a Miniature Neutron Source Reactor (MNSR). It was specifically acquired for elemental analysis by the neutron activation analysis (NAA) technique. In this work, routine experimental schemes for the determination of over 30 elements of interest in different sample matrices have been developed. In order to validate the experimental procedures the following standard reference materials, IAEA-359 (Cabbage), IAEA-336 (Lichen), GSR-5 and GSD-11 (Chinese Geochemical Rock Standards), as well as IAEA-SL-3 and IAEA-405 (Sediments) were analyzed. Validated results are presented for the following elements Al, As, Au, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Cu, Dy, Eu, Fe, Ga, Hf, In, K, La, Lu, Mg, Mn, Na, Rb, Sb, Sc, Sm, Ta, Tb, Th, Ti, U, V, Yb and Zn. To further assess analytical capabilities of the facilities, the detection limits are presented. PMID:16574418

  3. Neutron activation cross-sections at (14.6 ± 0.3) MeV

    Microsoft Academic Search

    H. M. Agrawal; Kailash Pandey; K. Surendra Babu; Ashok Kumar; R. Pepelnik

    2008-01-01

    The activation method has been used to measure 14.6MeV cross-sections for the following nine reactions which are important for nuclear energy programmes: 89Y(n,?)86mRb, 89Y(n,n?)89mY, 89Y(n,2n)88Y, 107Ag(n,n?)107mAg, 107Ag(n,p)107mPd, 109Ag(n,n?)109mAg, 109Ag(n,p)109mPd, 139La(n,p)139Ba, 139La(n,?)136Cs. Special features included a high-intensity neutron generator ‘KORONA’ with a useable fast neutron flux of 3×1014n\\/m2 s, a fast rabbit system suitable for cyclic irradiations and measurements for short-lived

  4. Nutrient elements of commercial tea from Nigeria by an instrumental neutron activation analysis technique.

    PubMed

    Jona, S A; Williams, I S

    2000-08-30

    A prototype miniature neutron source reactor (MNSR) with a thermal neutron flux of 3.0 x 10(11) n cm(-2) s(-1) has been used to determine the concentrations of some nutrient elements leading to short-lived activation products in commercial tea leaf samples from Nigeria. A total of eight elements Al, Ca, Cl, Cu, K, Mg, Mn and Na, that can be routinely used for quality control purposes, were analyzed in this study. Two biological reference materials, tomato leaves (NIST-1573) and citrus leaves (NIST-1572) were used as the standard and quality control materials, respectively. The analytical results show that the average concentrations of Al, Ca, Cl, Cu, K, Mg, Mn and Na in Nigerian tea are slightly higher when compared with a Chinese herbal tea analyzed in this study. The concentration ratios of K/Ca were found to be high in all the samples analyzed suggesting cultivation in potash-rich soils. PMID:11007291

  5. Instrumental neutron activation analysis of rib bone samples and of bone reference materials.

    PubMed

    Saiki, M; Takata, M K; Kramarski, S; Borelli, A

    1999-01-01

    The instrumental neutron activation analysis method was used for the determination of trace elements in rib bone samples taken from autopsies of accident victims. The elements Br, Ca, Cl, Cr, Fe, Mg, Mn, Na, P, Sr, Rb, and Zn were determined in cortical tissues by using short and long irradiations with thermal neutron flux of the IEA-R1m nuclear reactor. The reference materials NIST SRM 1400 Bone Ash and NIST SRM 1486 Bone Meal were also analyzed in order to evaluate the precision and the accuracy of the results. It was verified that lyophilization is the most convenient process for drying bone samples because it does not cause any element losses. Comparisons were made between the results obtained for rib samples and the literature values as well as between the results obtained for different ribs from a single individual and for bones from different individuals. PMID:10676477

  6. Activation cross sections for reactions induced by 14 MeV neutrons on natural tantalum

    SciTech Connect

    Luo Junhua [Department of Physics, Hexi University, Zhangye 734000 (China); School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Tuo Fei [National Institute for Radiological Protection, China CDC, Beijing 100088 (China); Kong Xiangzhong [Department of Physics, Hexi University, Zhangye 734000 (China)

    2009-05-15

    Cross sections for (n,2n), (n,p), (n,n{sup '}{alpha}), (n,t), (n,d{sup '}), and (n,{alpha}) reactions have been measured on tantalum isotopes at the neutron energies of 13.5 to 14.7 MeV using the activation technique. Data are reported for the following reactions: {sup 181}Ta(n,2n){sup 180}Ta{sup g}, {sup 181}Ta(n,p){sup 181}Hf, {sup 181}Ta(n,n{sup '}{alpha}){sup 177}Lu{sup m}, {sup 181}Ta(n,t){sup 179}Hf{sup m2}, {sup 181}Ta(n,d{sup '}){sup 180}Hf{sup m}, and {sup 181}Ta(n,{alpha}){sup 178}Lu{sup m}. The neutron fluences were determined using the monitor reaction {sup 27}Al(n,{alpha}){sup 24}Na. Results were discussed and compared with the previous works.

  7. Testing rate-dependent corrections on timing mode EPIC-pn spectra of the accreting neutron star GX 13+1

    NASA Astrophysics Data System (ADS)

    Pintore, F.; Sanna, A.; Di Salvo, T.; Guainazzi, M.; D'Aì, A.; Riggio, A.; Burderi, L.; Iaria, R.; Robba, N. R.

    2014-12-01

    When the EPIC-pn instrument on board XMM-Newton is operated in Timing mode, high count rates (>100 counts s-1) of bright sources may affect the calibration of the energy scale, resulting in a modification of the real spectral shape. The corrections related to this effect are then strongly important in the study of the spectral properties. Tests of these calibrations are more suitable in sources which spectra are characterized by a large number of discrete features. Therefore, in this work, we carried out a spectral analysis of the accreting neutron star GX 13+1, which is a dipping source with several narrow absorption lines and a broad emission line in its spectrum. We tested two different correction approaches on an XMM-Newton EPIC-pn observation taken in Timing mode: the standard rate-dependent charge transfer inefficiency (RDCTI or epfast) and the new, rate-dependent pulse height amplitude (RDPHA) corrections. We found that, in general, the two corrections marginally affect the properties of the overall broad-band continuum, while hints of differences in the broad emission line spectral shape are seen. On the other hand, they are dramatically important for the centroid energy of the absorption lines. In particular, the RDPHA corrections provide a better estimate of the spectral properties of these features than the RDCTI corrections. Indeed the discrete features observed in the data, applying the former method, are physically more consistent with those already found in other Chandra and XMM-Newton observations of GX 13+1.

  8. Development of the activation analysis calculational methodology for the Spallation Neutron Source (SNS)

    SciTech Connect

    Odano, N.; Johnson, J.O.; Charton, L.A.; Barnes, J.M.

    1998-03-01

    For the design of the proposed Spallation Neutron Source (SNS), activation analyses are required to determine the radioactive waste streams, on-line material processing requirements remote handling/maintenance requirements, potential site contamination and background radiation levels. For the conceptual design of the SNS, the activation analyses were carried out using the high-energy transport code HETC96 coupled with MCNP to generate the required nuclide production rates for the ORIHET95 isotope generation code. ORIHET95 utilizes a matrix-exponential method to study the buildup and decay of activities for any system for which the nuclide production rates are known. In this paper, details of the developed methodology adopted for the activation analyses in the conceptual design of the SNS are presented along with some typical results of the analyses.

  9. A study of neutron radiation quality with a tissue-equivalent proportional counter for a low-energy accelerator-based in vivo neutron activation facility.

    PubMed

    Aslam; Waker, A J

    2011-02-01

    The accelerator-based in vivo neutron activation facility at McMaster University has been used successfully for the measurement of several minor and trace elements in human hand bones due to their importance to health. Most of these in vivo measurements have been conducted at a proton beam energy (E(p)) of 2.00 MeV to optimise the activation of the selected element of interest with an effective dose of the same order as that received in chest X rays. However, measurement of other elements at the same facility requires beam energies other than 2.00 MeV. The range of energy of neutrons produced at these proton beam energies comes under the region where tissue-equivalent proportional counters (TEPCs) are known to experience difficulty in assessing the quality factor and dose equivalent. In this study, the response of TEPCs was investigated to determine the quality factor of neutron fields generated via the (7)Li(p, n)(7)Be reaction as a function of E(p) in the range 1.884-2.56 MeV at the position of hand irradiation in the facility. An interesting trend has been observed in the quality factor based on ICRP 60, Q(ICRP60), such that the maximum value was observed at E(p)=1.884 MeV (E(n)=33±16 keV) and then continued to decline with increasing E(p) until achieving a minimum value at E(p)=2.0 MeV despite a continuous increase in the mean neutron energy with E(p). This observation is contrary to what has been observed with direct fast neutrons where the quality factor was found to increase continuously with an increase in E(p) (i.e. increasing E(n)). The series of measurements conducted with thermal and fast neutron fields demonstrate that the (14)N(n, p)(14)C produced 580 keV protons in the detector play an important role in the response of the counter under 2.0 MeV proton energy (E(n) ? 250 keV). In contrast to the lower response of TEPCs to low-energy neutrons, the quality factor is overestimated in the range 1-2 depending on beam energy <2.0 MeV. This study provides an insight to understanding the response of TEPCs in low-energy neutron fields where the neutrons are moderated using a polyethylene moderator. PMID:21183541

  10. Infrared spectra of obscuring dust tori around active galactic nuclei. I - Calculational method and basic trends

    NASA Technical Reports Server (NTRS)

    Pier, Edward A.; Krolik, Julian H.

    1992-01-01

    Using a new 2D radiative transfer algorithm, we have calculated the thermally reradiated infrared spectra of the compact dust tori which are thought to surround many AGN. These tori radiate anisotropically. Face-on tori may be from one-half to a few orders of magnitude brighter than edge-on tori throughout the infrared. Their spectra at nearly all viewing angles are basically 'bumps' which are about 50 percent wider than blackbodies and peak in the mid-infrared at a wavelength determined mainly by the flux of nuclear radiation on the inner edge of the torus. The infrared color temperatures are hotter for face-on tori than edge-on tori by about 100 K. The 10 micron silicate feature often associated with dust can appear in absorption, emission, or not at all. There is a rough tendency for absorption features to be more prominent for edge-on tori than for face-on tori.

  11. Computer-aided discovery of biological activity spectra for anti-aging and anti-cancer olive oil oleuropeins

    PubMed Central

    Corominas-Faja, Bruna; Santangelo, Elvira; Cuyàs, Elisabet; Micol, Vicente; Joven, Jorge; Ariza, Xavier; Segura-Carretero, Antonio; García, Jordi; Menendez, Javier A.

    2014-01-01

    Aging is associated with common conditions, including cancer, diabetes, cardiovascular disease, and Alzheimer's disease. The type of multi-targeted pharmacological approach necessary to address a complex multifaceteddisease such as aging might take advantage of pleiotropic natural polyphenols affecting a wide variety of biological processes. We have recently postulated that the secoiridoids oleuropein aglycone (OA) and decarboxymethyl oleuropein aglycone (DOA), two complex polyphenols present in health-promoting extra virgin olive oil (EVOO), might constitute anew family of plant-produced gerosuppressant agents. This paper describes an analysis of the biological activity spectra (BAS) of OA and DOA using PASS (Prediction of Activity Spectra for Substances) software. PASS can predict thousands of biological activities, as the BAS of a compound is an intrinsic property that is largely dependent on the compound's structure and reflects pharmacological effects, physiological and biochemical mechanisms of action, and specific toxicities. Using Pharmaexpert, a tool that analyzes the PASS-predicted BAS of substances based on thousands of “mechanism-effect” and “effect-mechanism” relationships, we illuminate hypothesis-generating pharmacological effects, mechanisms of action, and targets that might underlie the anti-aging/anti-cancer activities of the gerosuppressant EVOO oleuropeins. PMID:25324469

  12. Computer-aided discovery of biological activity spectra for anti-aging and anti-cancer olive oil oleuropeins.

    PubMed

    Corominas-Faja, Bruna; Santangelo, Elvira; Cuyàs, Elisabet; Micol, Vicente; Joven, Jorge; Ariza, Xavier; Segura-Carretero, Antonio; García, Jordi; Menendez, Javier A

    2014-09-01

    Aging is associated with common conditions, including cancer, diabetes, cardiovascular disease, and Alzheimer's disease. The type of multi-targeted pharmacological approach necessary to address a complex multifaceted disease such as aging might take advantage of pleiotropic natural polyphenols affecting a wide variety of biological processes. We have recently postulated that the secoiridoids oleuropein aglycone (OA) and decarboxymethyl oleuropein aglycone (DOA), two complex polyphenols present in health-promoting extra virgin olive oil (EVOO), might constitute a new family of plant-produced gerosuppressant agents. This paper describes an analysis of the biological activity spectra (BAS) of OA and DOA using PASS (Prediction of Activity Spectra for Substances) software. PASS can predict thousands of biological activities, as the BAS of a compound is an intrinsic property that is largely dependent on the compound's structure and reflects pharmacological effects, physiological and biochemical mechanisms of action, and specific toxicities. Using Pharmaexpert, a tool that analyzes the PASS-predicted BAS of substances based on thousands of "mechanism-effect" and "effect-mechanism" relationships, we illuminate hypothesis-generating pharmacological effects, mechanisms of action, and targets that might underlie the anti-aging/anti-cancer activities of the gerosuppressant EVOO oleuropeins. PMID:25324469

  13. Supercool Neutrons (Ultracold Neutrons)

    E-print Network

    Martin, Jeff

    Supercool Neutrons (Ultracold Neutrons) Jeff Martin University of Winnipeg Skywalk 2007 Manitoba Research & Innovation Fund #12; Ultracold Neutrons What are neutrons? Why are they important? How to make lots of neutrons. Interesting properties of ultracold neutrons (UCN) Supercool

  14. Tracing footprints of environmental events in tree ring chemistry using neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Sahin, Dagistan

    The aim of this study is to identify environmental effects on tree-ring chemistry. It is known that industrial pollution, volcanic eruptions, dust storms, acid rain and similar events can cause substantial changes in soil chemistry. Establishing whether a particular group of trees is sensitive to these changes in soil environment and registers them in the elemental chemistry of contemporary growth rings is the over-riding goal of any Dendrochemistry research. In this study, elemental concentrations were measured in tree-ring samples of absolutely dated eleven modern forest trees, grown in the Mediterranean region, Turkey, collected and dated by the Malcolm and Carolyn Wiener Laboratory for Aegean and Near Eastern Dendrochronology laboratory at Cornell University. Correlations between measured elemental concentrations in the tree-ring samples were analyzed using statistical tests to answer two questions. Does the current concentration of a particular element depend on any other element within the tree? And, are there any elements showing correlated abnormal concentration changes across the majority of the trees? Based on the detailed analysis results, the low mobility of sodium and bromine, positive correlations between calcium, zinc and manganese, positive correlations between trace elements lanthanum, samarium, antimony, and gold within tree-rings were recognized. Moreover, zinc, lanthanum, samarium and bromine showed strong, positive correlations among the trees and were identified as possible environmental signature elements. New Dendrochemistry information found in this study would be also useful in explaining tree physiology and elemental chemistry in Pinus nigra species grown in Turkey. Elemental concentrations in tree-ring samples were measured using Neutron Activation Analysis (NAA) at the Pennsylvania State University Radiation Science and Engineering Center (RSEC). Through this study, advanced methodologies for methodological, computational and experimental NAA were developed to ensure an acceptable accuracy and certainty in the elemental concentration measurements in tree-ring samples. Two independent analysis methods of NAA were used; the well known k-zero method and a novel method developed in this study, called the Multi-isotope Iterative Westcott (MIW) method. The MIW method uses reaction rate probabilities for a group of isotopes, which can be calculated by a neutronic simulation or measured by experimentation, and determines the representative values for the neutron flux and neutron flux characterization parameters based on Westcott convention. Elemental concentration calculations for standard reference material and tree-ring samples were then performed using the MIW and k-zero analysis methods of the NAA and the results were cross verified. In the computational part of this study, a detailed burnup coupled neutronic simulation was developed to analyze real-time neutronic changes in a TRIGA Mark III reactor core, in this study, the Penn State Breazeale Reactor (PSBR) core. To the best of the author`s knowledge, this is the first burnup coupled neutronic simulation with realistic time steps and full fuel temperature profile for a TRIGA reactor using Monte Carlo Utility for Reactor Evolutions (MURE) code and Monte Carlo Neutral-Particle Code (MCNP) coupling. High fidelity and flexibility in the simulation was aimed to replicate the real core operation through the day. This approach resulted in an enhanced accuracy in neutronic representation of the PSBR core with respect to previous neutronic simulation models for the PSBR core. An important contribution was made in the NAA experimentation practices employed in Dendrochemistry studies at the RSEC. Automated laboratory control and analysis software for NAA measurements in the RSEC Radionuclide Applications Laboratory was developed. Detailed laboratory procedures were written in this study comprising preparation, handling and measurements of tree-ring samples in the Radionuclide Applications Laboratory.

  15. Determination of multielements in a typical Japanese diet certified reference material by instrumental neutron activation analysis.

    PubMed

    Suzuki, Shogo; Okada, Yukiko; Hirai, Shoji

    2003-08-01

    Multielements in a typical Japanese diet certified reference material prepared at the National Institute for Environmental Studies (NIES) of Japan, in collaboration with the National Institute of Radiological Sciences (NIRS) of Japan were determined by instrumental neutron activation analysis (INAA). Five samples (ca. 510-1000 mg) and comparative standards were irradiated for a short time (10 s) at a thermal neutron flux of 1.5 x 10(12) n cm(-2) s(-1) (pneumatic transfer) and for a long time (6 h) at a thermal neutron flux of 3.7 x 10(12) n cm(-2) s(-1) (central thimble) in the Rikkyo University Research Reactor (TRIGA Mark-II, 100 kW). The irradiated samples were measured by conventional gama-ray spectrometry using a coaxial Ge detector, and by anti-coincidence and coincidence gamma-ray spectrometry with a coaxial Ge detector and a well-type NaI(Tl) detector. The concentrations of 38 elements were determined by these methods. PMID:12945682

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

    SciTech Connect

    Livingston, R. A.; Al-Sheikhly, M. [Materials Science and Engineering Dept., U. of Maryland, College Park MD 20742 (United States); Grissom, C.; Aloiz, E. [Museum Conservation Institute, Smithsonian Institution, Washington DC 20746 (United States); Paul, R. [Chemical Sciences Division, NIST, Gaithersburg MD 20899 (United States)

    2014-02-18

    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.

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

    NASA Astrophysics Data System (ADS)

    Livingston, R. A.; Al-Sheikhly, M.; Grissom, C.; Aloiz, E.; Paul, R.

    2014-02-01

    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.

  18. Investigation of the microstructure of alkali-activated cements by neutron scattering

    SciTech Connect

    Phair, J.W.; Schulz, J.C.; Bertram, W.K.; Aldridge, L.P

    2003-11-01

    Significant research has been devoted to understanding and modeling the neutron scattering behavior of Portland cement pastes. The present work examines the potential of neutron scattering to noninvasively evaluate the properties of alternative cementitious materials encountered in the field. To interpret the scattering of both alkali-activated and slag-cement systems, alternative models to those typically adopted for Portland cement pastes were considered. Investigation of alkali-activated and slag-cement coupons were conducted for different sample thickness ({approx}0.5, 1, 2, 4, 6, 8 and 12 mm) over a wide scattering vector (Q) range (0.00050.03 nm{sup -1} and 0.044 nm{sup -1}) on both ultra (USANS) and conventional small-angle neutron scattering (SANS) spectrometers. This wide Q range allowed determination of the fractal properties of the microstructure as well as the radius of the main scattering particle in the material. An empirical correction for multiple scattering was made based on the Dexter-Beeman equation and demonstrated that for thicker sample widths the theory correlated reasonably well. Alkali-activated fly ash was found to have the largest R value while the OPC and slag mix exhibited the largest Guinier radius. This difference was attributed to variations in the extent of multiple scattering for the samples. Successful application of this model was limited to sample thickness {>=}1 mm. A combined power law-Sabine expression was also utilized to successfully model the SANS data over a Q range of 0.04-4 nm{sup -1}.

  19. The Prompt Gamma Neutron Activation Analysis Facility at ICN-Pitesti

    SciTech Connect

    Barbos, D.; Paunoiu, C.; Mladin, M. [Institute for Nuclear Research, Pitesti-Mioveni, 115400 (Romania); Cosma, C. [University Babes-Bolyai, Cluj-Napoca(Romania)

    2008-08-14

    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 performance of INAA method. A facility has been developed at Institute for Nuclear Research-Pitesti 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: {phi}{sub scd} = 1.10{sup 6} n/cm{sup 2}/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 deg. 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.

  20. Multi-element analysis of emeralds and associated rocks by k(o) neutron activation analysis

    PubMed

    Acharya; Mondal; Burte; Nair; Reddy; Reddy; Reddy; Manohar

    2000-12-01

    Multi-element analysis was carried out in natural emeralds, their associated rocks and one sample of beryl obtained from Rajasthan, India. The concentrations of 21 elements were assayed by Instrumental Neutron Activation Analysis using the k0 method (k0 INAA method) and high-resolution gamma ray spectrometry. The data reveal the segregation of some elements from associated (trapped and host) rocks to the mineral beryl forming the gemstones. A reference rock standard of the US Geological Survey (USGS BCR-1) was also analysed as a control of the method. PMID:11077961

  1. Neutron activation analysis of LWR mixted-bed resins for sup 129 I

    SciTech Connect

    Graudons, J.A.; Dyer, F.F.

    1992-01-01

    Iodine-129 was determined by neutron activation analysis (NAA) in mixed-bed ion exchange resins from four light water reactors (LWR), including two pressurized water reactors (PWR) and two boiling water reactors (BWR). Published procedures for NAA of {sup 129}I in LWR resins were modified and adapted to the particular requirements of the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor (HFIR) irradiation system. Observed {sup 129}I concentrations were about 1000 times higher than the beta-gamma detection limits currently reported.

  2. Determination of hydrogen content in bulk samples using the neutron activation method.

    PubMed

    Dóczi, R; Ali, M A; Fayez-Hassan, M; Csikai, J

    2005-07-01

    The applicability of a new irradiation facility for bulk hydrogen analysis based on the activation method using thermal and epithermal neutrons has been tested for cylindrical samples of 8 cm diameter and 10 cm high. A definite correlation was found between the relative excess flux values, R and the total hydrogen contents, N(H) of the samples. Analytical expressions obtained for R vs. N(H) function indicate the possible use of this method even in the case of approximately kg weight and liter sample dimensions. The large sample has a special advantage if the determination of the hydrogen concentration, C(H) is in question. PMID:15866459

  3. Simultaneous determination of tantalum and hafnium in silicates by neutron activation analysis

    USGS Publications Warehouse

    Greenland, L.P.

    1968-01-01

    A neutron activation procedure suitable for the routine determination of tantalum and hafnium in silicates is described. The irradiated sample is fused with sodium peroxide and leached, and the insoluble hydroxides are dissolved in dilute hydrofluoric acid-hydrochloric acid. After LaF3 and AgCl scavenges, tantalum and hafnium are separated by anion exchange. Tantalum is obtained radiochemically pure; 233Pa and 95Zr contaminants in the hafnium fraction are resolved by ??-ray spectrometry. The chemical yield of the procedure is detemined after counting by re-irradiation. Values for the 8 U.S. Geological Survey standard rocks are reported. ?? 1968.

  4. On the determination of trace elements in cocoa and coffee by instrumental neutron activation analysis 

    E-print Network

    Adanuvor, Prosper Kwasi

    1980-01-01

    rom . he analysis of green coffee or as estimated from roast coffee sample. Shah et al. (14) have used Neutron Activation Analysis to determine Na, K, Sc, Cr, Mn, Fe, Co, Cu, Zn, Se, Br, Rb, Cs, and Hg in ground coffee, instant coffee, and tea... Cu Al Cl Mn Ca Cr II' Cd Br P. s Au Sc Sb Bb Fe Zn Co Na K La 4108. 21 39 II 4 15. 38 4 II 8. 13 + 4. 69 + 2 52 . 0014 22 43 16. 90 69. 89 46. 26 . 31 5. 14 + . 0001 + . 06 + 79 + 9 ~ '(0 + ]. 90 . 04 + . 30 6470...

  5. Simple radiochemical neutron-activation method for the determination of uranium in ultramafic rocks.

    PubMed

    Steinnes, E

    1975-12-01

    A radiochemical neutron-activation method for the determination of trace concentrations of uranium in rocks is described. The method is based on separation of 23.5-min (239)U after alkaline fusion by extraction with tri-n-butyl phosphate from moderately concentrated nitric acid, followed by measurement of the 74-keV gamma-ray with a Ge(Li) detector. The limit of detection is 0.2 ng of U under the present conditions, and the precision at the 0.005 ppm level is about 10%. The method is especially useful for determination of uranium in ultramafic rocks. PMID:18961784

  6. Determination of carrier yields for neutron activation analysis using energy dispersive X-ray spectrometry

    USGS Publications Warehouse

    Johnson, R.G.; Wandless, G.A.

    1984-01-01

    A new method is described for determining carrier yield in the radiochemical neutron activation analysis of rare-earth elements in silicate rocks by group separation. The method involves the determination of the rare-earth elements present in the carrier by means of energy-dispersive X-ray fluorescence analysis, eliminating the need to re-irradiate samples in a nuclear reactor after the gamma ray analysis is complete. Results from the analysis of USGS standards AGV-1 and BCR-1 compare favorably with those obtained using the conventional method. ?? 1984 Akade??miai Kiado??.

  7. Determination of 18 trace elements in petroleum and its derivatives by neutron activation with a small nuclear reactor

    Microsoft Academic Search

    C. Bergerioux; L. Zikovsky

    1978-01-01

    Non-destructive neutron activation has been used to analyze 6 different samples of crude oil and heating oil, from Western\\u000a Canada and Venezuela. These samples were irradiated with thermal neutrons for 2, 30 and 240 min in the SLOWPOKE reactor and\\u000a the concentrations of 18 trace and minor elements (Al, As, Br, Cl, Co, Dy, Eu, Fe, I, La, Mn, Mo,

  8. A study of the elemental composition of diabases by instrumental neutron activation and X-ray fluorescence analysis

    Microsoft Academic Search

    A. V. Gurevich; Z. V. Vikhrova; V. Ya Vyropayev; V. I. Drynkin; D. I. Leipunskaya; I. Ya. Shirokova

    1980-01-01

    The distribution of the elemental composition was studied mainly for microelements in the diabases of the Pechenga suite subjected\\u000a to various changes. Investigations were conducted by a combination of instrumental neutron activation INAA and X-ray fluoresence\\u000a XRFA analyses. The INAA was conducted with sample weights of 20–100 mg exposed to irradiation in a nuclear reactor by a flux\\u000a of neutrons

  9. Calculation of response matrix of CaSO 4:Dy based neutron dosimeter using Monte Carlo code FLUKA and measurement of 241Am-Be spectra

    NASA Astrophysics Data System (ADS)

    Chatterjee, S.; Bakshi, A. K.; Tripathy, S. P.

    2010-09-01

    Response matrix for CaSO 4:Dy based neutron dosimeter was generated using Monte Carlo code FLUKA in the energy range thermal to 20 MeV for a set of eight Bonner spheres of diameter 3-12? including the bare one. Response of the neutron dosimeter was measured for the above set of spheres for 241Am-Be neutron source covered with 2 mm lead. An analytical expression for the response function was devised as a function of sphere mass. Using Frascati Unfolding Iteration Tool (FRUIT) unfolding code, the neutron spectrum of 241Am-Be was unfolded and compared with standard IAEA spectrum for the same.

  10. Detecting Phase Coupling of Gastric Interdigestive Pressure Activity via Diagonal Slice Spectra.

    PubMed

    Yan, Rongguo; Yan, Guozheng; Zhang, Wenqiang; Wang, Long

    2005-01-01

    We propose a new analysis method to detect phase coupling behaviour of the human gastric interdigestive pressure wave that has been acquired by a telemetric capsule-like mini-robot. The method is referred to as diagonal slice spectra, which are the Fourier transforms of the diagonal slices of the triple correlation and can detect the phase coupling and coupled components respectively. It is shown that nonlinear quadratic phase coupling occurs during gastric contraction (phase II), whereas no distinct phase coupling occurs during gastric motor quiescence (phase I). PMID:17282176

  11. ASCA X-ray spectra of the active single stars Beta Ceti and pi(1) Ursae Majoris

    NASA Technical Reports Server (NTRS)

    Drake, S. A.; Singh, K. P.; White, N. E.; Simon, Theodore

    1994-01-01

    We present X-ray spectra obtaiined by ASCA of two single, active stars, the G dwarf pi(1) UMa, and the G9/K0 giant Beta Cet. The spectra of both stars require the presence of at least two plasma components with different temperatures, 0.3-0.4 keV and approximately 0.7 keV, in order for acceptable fits to be obtained. The spectral resolving power and signal-to-noise ratio of the solid state imaging spectrometer (SIS) spectra allow us to formally constrain the coronal abundances of a number of elements. In Beta Cet, we find Mg to be overabundant, while other elements such as O, Ne, and N are underabundant, relative to the solar photospheric values. From the lower signal-to-noise ratio SIS spectrum of pi(1) UMa, we find evidence for underabundances of O, Ne, and Fe. These results are discussed in the context of the present understanding of elemental abundances in solar and stellar coronae.

  12. Summary report for ITER task - D10: Update and implementation of neutron transport and activation codes and processed libraries

    SciTech Connect

    Attaya, H.

    1995-01-01

    The primary goal of this task is to provide the capabilities in the activation code RACC, to treat pulsed operation modes. In addition, it is required that the code utilizes the same spatial mesh and geometrical models as employed in the one or multidimensional neutron transport codes used in ITER design. This would ensure the use of the same neutron flux generated by those codes to calculate the different activation parameters. It is also required to have the capabilities for generating graphical outputs for the calculated activation parameters.

  13. Neutron features at the UPM neutronics hall.

    PubMed

    Rene Vega-Carrillo, Hector; Gallego, Eduardo; Lorente, Alfredo; Rubio, Isabel P; Méndez, Roberto

    2012-08-01

    The neutronics hall of the Nuclear Engineering Department at the Polytechnical University of Madrid has been characterized. The neutron spectra and the ambient dose equivalent produced by an (241)AmBe source were measured at various source-to-detector distances on the new bench. Using Monte Carlo methods a detailed model of the neutronics hall was designed, and neutron spectra and the ambient dose equivalent were calculated at the same locations where measurements were carried out. A good agreement between measured and calculated values was found. PMID:22738835

  14. An investigation of the neutron flux in bone-fluorine phantoms comparing accelerator based in vivo neutron activation analysis and FLUKA simulation data

    NASA Astrophysics Data System (ADS)

    Mostafaei, F.; McNeill, F. E.; Chettle, D. R.; Matysiak, W.; Bhatia, C.; Prestwich, W. V.

    2015-01-01

    We have tested the Monte Carlo code FLUKA for its ability to assist in the development of a better system for the in vivo measurement of fluorine. We used it to create a neutron flux map of the inside of the in vivo neutron activation analysis irradiation cavity at the McMaster Accelerator Laboratory. The cavity is used in a system that has been developed for assessment of fluorine levels in the human hand. This study was undertaken to (i) assess the FLUKA code, (ii) find the optimal hand position inside the cavity and assess the effects on precision of a hand being in a non-optimal position and (iii) to determine the best location for our ?-ray detection system within the accelerator beam hall. Simulation estimates were performed using FLUKA. Experimental measurements of the neutron flux were performed using Mn wires. The activation of the wires was measured inside (1) an empty bottle, (2) a bottle containing water, (3) a bottle covered with cadmium and (4) a dry powder-based fluorine phantom. FLUKA was used to simulate the irradiation cavity, and used to estimate the neutron flux in different positions both inside, and external to, the cavity. The experimental results were found to be consistent with the Monte Carlo simulated neutron flux. Both experiment and simulation showed that there is an optimal position in the cavity, but that the effect on the thermal flux of a hand being in a non-optimal position is less than 20%, which will result in a less than 10% effect on the measurement precision. FLUKA appears to be a code that can be useful for modeling of this type of experimental system.

  15. Neutron-emission measurements at a white neutron source

    SciTech Connect

    Haight, Robert C [Los Alamos National Laboratory

    2010-01-01

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

  16. MIT-EAPS Neutron Activation Analysis and Radiometric Laboratory Contribution to Geosciences: Past, Present, and Future

    SciTech Connect

    Pillalamarri, Ila [Department of Earth Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2005-09-08

    The Instrumental Neutron Activation Analysis (INAA) and Radiometric Laboratory's current system is described. This laboratory has been in continuous operation for the past thirty years. A review is provided about the laboratory's analytical participation in trace element geochemical studies of the earth's upper mantle, trace impurity studies of high purity materials, the provenance study of archaeological glass beads, trace multi-element analyses of standard reference materials, the preparation of synthetic analytical standards for Neutron Activation Analysis, and providing a training course in nuclear analytical techniques for environmental samples. The multi-element analysis by INAA consists of determining elements like the rare earths La, Ce, Nd, Sm Eu, Tb, Dy, Ho, Yb, Lu, and also As, Ba, Cl, Co, Cr, Cs, Dy, Fe, Hf, Hg, K, Mn, Na, Ta, Th, U. The projected future of the laboratory is explained in terms of its resources, expertise in high precision analysis of trace impurities for the material selection that is to be used in rare event physics experiments. For example, this 'surface' laboratory can be efficiently interfaced/integrated with a deep underground low background counting facility, especially in the initial stages.

  17. Standard-less analysis of Zircaloy clad samples by an instrumental neutron activation method

    NASA Astrophysics Data System (ADS)

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

    2004-03-01

    A non-destructive method for analysis of irregular shape and size samples of Zircaloy has been developed using the recently standardized k0-based internal mono standard instrumental neutron activation analysis (INAA). The samples of Zircaloy-2 and -4 tubes, used as fuel cladding in Indian boiling water reactors (BWR) and pressurized heavy water reactors (PHWR), respectively, have been analyzed. Samples weighing in the range of a few tens of grams were irradiated in the thermal column of Apsara reactor to minimize neutron flux perturbations and high radiation dose. The method utilizes in situ relative detection efficiency using the ?-rays of selected activation products in the sample for overcoming ?-ray self-attenuation. Since the major and minor constituents (Zr, Sn, Fe, Cr and/or Ni) in these samples were amenable to NAA, the absolute concentrations of all the elements were determined using mass balance instead of using the concentration of the internal mono standard. Concentrations were also determined in a smaller size Zircaloy-4 sample by irradiating in the core position of the reactor to validate the present methodology. The results were compared with literature specifications and were found to be satisfactory. Values of sensitivities and detection limits have been evaluated for the elements analyzed.

  18. Radiological and instrumental neutron activation analysis determined characteristics of size-fractionated fly ash.

    PubMed

    Peppas, T K; Karfopoulos, K L; Karangelos, D J; Rouni, P K; Anagnostakis, M J; Simopoulos, S E

    2010-09-15

    The concentration of trace elements and radionuclides in fly ash particles of different size can exhibit significant variation, due to the various processes taking place during combustion inside a coal-fired power plant. An investigation of this effect has been performed by analyzing samples of fly ash originating in two different coal-fired power plants, after separation into size fractions by sieving. The samples were analyzed by gamma-ray spectrometry, including low-energy techniques, radon exhalation measurement and instrumental neutron activation analysis for the determination of Al, As, Ga, K, La, Na, Mn, Mg, Sr, Sc, and V. Variations are observed in the results of various samples analyzed, while the activity balances calculated from the results of individual size fractions are consistent with those of the raw ash samples. Correlations among the radionuclides examined are also observed, while individual nuclide behavior varies between the two types of fly ash examined. PMID:20605322

  19. Ion Uptake Determination of Dendrochronologically-Dated Trees Using Neutron Activation Analysis

    SciTech Connect

    Kenan Unlu; P.I. Kuniholm; D.K.H. Schwarz; N.O. Cetiner; J.J. Chiment

    2009-03-30

    Uptake of metal ions by plan roots is a function of the type and concentration of metal in the soil, the nutrient biochemistry of the plant, and the immediate environment of the root. Uptake of gold (Au) is known to be sensitive to soil pH for many species. Soil acidification due to acid precipitation following volcanic eruptions can dramatically increase Au uptake by trees. Identification of high Au content in tree rings in dendrochronologically-dated, overlapping sequences of trees allows the identification of temporally-conscribed, volcanically-influenced periods of environmental change. Ion uptake, specifically determination of trace amounts of gold, was performed for dendrochronologically-dated tree samples utilizing Neutron Activation Analysis (NAA) technique. The concentration of gold was correlated with known enviironmental changes, e.g. volcanic activities, during historic periods.

  20. Studies on separation and purification of fission (99)Mo from neutron activated uranium aluminum alloy.

    PubMed

    Rao, Ankita; Kumar Sharma, Abhishek; Kumar, Pradeep; Charyulu, M M; Tomar, B S; Ramakumar, K L

    2014-07-01

    A new method has been developed for separation and purification of fission (99)Mo from neutron activated uranium-aluminum alloy. Alkali dissolution of the irradiated target (100mg) results in aluminum along with (99)Mo and a few fission products passing into solution, while most of the fission products, activation products and uranium remain undissolved. Subsequent purification steps involve precipitation of aluminum as Al(OH)3, iodine as AgI/AgIO3 and molybdenum as Mo-?-benzoin oxime. Ruthenium is separated by volatilization as RuO4 and final purification of (99)Mo was carried out using anion exchange method. The radiochemical yield of fission (99)Mo was found to be >80% and the purity of the product was in conformity with the international pharmacopoeia standards. PMID:24657474

  1. CCN spectra, hygroscopicity, and droplet activation kinetics of secondary organic aerosol resulting from the 2010 Deepwater Horizon oil spill.

    PubMed

    Moore, Richard H; Raatikainen, Tomi; Langridge, Justin M; Bahreini, Roya; Brock, Charles A; Holloway, John S; Lack, Daniel A; Middlebrook, Ann M; Perring, Anne E; Schwarz, Joshua P; Spackman, J Ryan; Nenes, Athanasios

    2012-03-20

    Secondary organic aerosol (SOA) resulting from the oxidation of organic species emitted by the Deepwater Horizon oil spill were sampled during two survey flights conducted by a National Oceanic and Atmospheric Administration WP-3D aircraft in June 2010. A new technique for fast measurements of cloud condensation nuclei (CCN) supersaturation spectra called Scanning Flow CCN Analysis was deployed for the first time on an airborne platform. Retrieved CCN spectra show that most particles act as CCN above (0.3 ± 0.05)% supersaturation, which increased to (0.4 ± 0.1)% supersaturation for the most organic-rich aerosol sampled. The aerosol hygroscopicity parameter, ?, was inferred from both measurements of CCN activity and from humidified-particle light extinction, and varied from 0.05 to 0.10 within the emissions plumes. However, ? values were lower than expected from chemical composition measurements, indicating a degree of external mixing or size-dependent chemistry, which was reconciled assuming bimodal, size-dependent composition. The CCN droplet effective water uptake coefficient, ?(cond), was inferred from the data using a comprehensive instrument model, and no significant delay in droplet activation kinetics from the presence of organics was observed, despite a large fraction of hydrocarbon-like SOA present in the aerosol. PMID:22356579

  2. Automated system for neutron activation analysis determination of short lived isotopes at The DOW Chemical Company's TRIGA research reactor

    NASA Astrophysics Data System (ADS)

    Zieman, J. J.; Rigot, W. L.; Romick, J. D.; Quinn, T. J.; Kocher, C. W.

    1994-12-01

    An automated neutron activation analysis (NAA) system for the determination of short lived isotopes was constructed at The DOW Chemical Company's TRIGA Research Reactor in 1993. The NAA group of the Analytical Sciences Laboratory uses the reactor for thousands of analyses each year and therefore automation is important to achieve and maintain high throughput and precision (productivity). This project is complementary to automation of the long-lived counting facilities (see Romick et al., these Proceedings). Canberra/Nuclear Data Systems DEC-based software and electronics modules and an I/O mounting board are the basic commercial components. A Fortran program on a VAX computer controls I/O via ethernet to an Acquisition Interface Module (AIM). The AIM controls the ? spectrometer modules and is interfaced to a Remote Parallel Interface (RPI) module which controls the pneumatic transfer apparatus with TTL signals to the I/O mounting board. Near-infrared sensors are used to monitor key points in the transfer system. Spectra are acquired by a single HPGe detector mounted on a sliding rail to allow flexible and more reproducible counting geometries than with manual sample handling. The maximum sample size is 8 ml in a heat-sealed two dram vial. The sample vial is nested into a "rabbit" vial for irradiation which can be automatically removed prior to spectrum collection. The system was designed to be used by the reactor operator at the control console without the aid of an additional experimenter. Applications include the determination of selenium and silver in coal and water, fluorine in tetra-fluoro ethylene (TFE) coated membranes, aluminum and titanium in composite materials and trace fluorine in non-chlorinated cleaning solvents. Variable dead time software allows analysis for 77mSe despite high dead times from 16N encountered in samples.

  3. Measurement of neutron activation cross sections of energy up to 40 MeV using semimonoenergetic p-Be neutrons

    Microsoft Academic Search

    Y. Uwamino; H. Sugita; Y. Kondo; T. Nakamura

    1992-01-01

    This paper discusses an intense semimonoenergetic neutron field which was made using a simple beryllium target system bombarded by protons of nine different energies between 20 and 40 MeV. Natural sodium, aluminum, vanadium, chromium, manganese, copper, zinc, and gold samples were irradiated at this field, and gamma rays from the samples were observed by a germanium detector. The production rates

  4. The Age-Activity Relation for M dwarfs Using 25,000 SDSS Spectra

    NASA Astrophysics Data System (ADS)

    Hawley, Suzanne L.; West, A. A.; Bochanski, J. J.; Covey, K. R.

    2006-12-01

    The age at which strong surface magnetic activity ceases in M dwarfs has been inferred to have a strong dependence on mass (spectral type, surface temperature) to explain previous results showing a large increase in the fraction of active stars at later spectral types. Using spectral observations of 25,000 M dwarfs in the SDSS, we show that the fraction of active stars decreases as a function of vertical distance from the Galactic plane, and that the magnitude of this decrease changes significantly for different M spectral types. Adopting a simple dynamical model for thin disk vertical heating, we assign an age for the activity decline at each spectral type, and thus determine an activity-age relation for M dwarfs. These results provide constraints for dynamo models that seek to describe the production of surface magnetic fields in low mass stars.

  5. HOTSPUR: gamma ray emission from spheres pulsed with D-T neutrons. I. Calibration of improved NE213 detector assembly. II. Comparison of TART/SANDYL electron recoil spectra to experiment; preliminary results

    SciTech Connect

    Goldberg, E.; Hansen, L.F.; Komoto, T.T.; Pohl, B.A.

    1986-09-01

    The NE213 scintillator detector was modified so that the pulse height would be linear with electron energy over the full range of interest - up to 7.1 MeV. Absolute calibration was done with four different calibrated gamma sources. An average correction factor is obtained which normalizes SANDYL calculations with respect to the calibration experiments. The procedure for calculating neutron-induced gamma-ray output and electron recoil spectra is described, and experimental data from a number of spherical assemblies are given and compared to TART/SANDYL calculations. (LEW)

  6. Small-angle neutron and X-ray scattering reveal conformational changes in rhodopsin activation

    NASA Astrophysics Data System (ADS)

    Shrestha, Utsab R.; Bhowmik, Debsindhu; Perera, Suchitrhanga M. C. D.; Chawla, Udeep; Struts, Andrey V.; Graziono, Vito; Pingali, Sai Venkatesh; Heller, William T.; Qian, Shuo; Brown, Michael F.; Chu, Xiang-Qiang

    2015-03-01

    Understanding G-protein-coupled receptor (GPCR) activation plays a crucial role in the development of novel improved molecular drugs. During photo-activation, the retinal chromophore of the visual GPCR rhodopsin isomerizes from 11-cis to all-trans conformation, yielding an equilibrium between inactive Meta-I and active Meta-II states. The principal goals of this work are to address whether the activation of rhodopsin leads to a single state or a conformational ensemble, and how protein organizational structure changes with detergent environment in solution. We use both small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) techniques to answer the above questions. For the first time we observe the change in protein conformational ensemble upon photo-activation by SANS with contrast variation, which enables the separate study of the protein structure within the detergent assembly. In addition, SAXS study of protein structure within detergent assembly suggests that the detergent molecules form a belt of monolayer (micelle) around protein with different geometrical shapes to keep the protein in folded state.

  7. CYTOKININS: SYNTHESIS, MASS SPECTRA, AND BIOLOGICAL ACTIVITY OF COMPOUNDS RELATED TO ZEATIN*

    PubMed Central

    Leonard, Nelson J.; Hecht, Sidney M.; Skoog, Folke; Schmitz, Ruth Y.

    1969-01-01

    Compounds related to dihydrozeatin that define the influence of the location of the hydroxyl group along the side chain have been synthesized and tested for cytokinin activity. The compounds compared are in the series: 6-(X-hydroxy-3-methylbutylamino)purines and their ribosides, where X = 2, 3, and 4. Hydroxy substitution on the 4-position of the side chain enhances, but in the 2-, 3-, or 2- and 3- positions, decreases cytokinin activity as compared with the unsubstituted isopentyl (or isopentenyl) chains. This differential influence of the position of the hydroxyl group in the N6-chain holds also for the similarly related 9-?-D-ribofuranosides. The relatively higher activity of 3,4-dihydroxy as compared with 2,3-dihydroxy derivatives is consistent with this position effect. Compounds related to zeatin possessing side-chain ester moieties have also been synthesized and tested comparatively. Among these, 6-(4-acetoxy-3-methyl-trans-2-butenylamino)purine is at least as active as zeatin, the most active presently known cytokinin in the tobacco bioassay, whereas the analog, methyl 2-methyl-4-(purin-6-ylamino)-trans-crotonate, with the ester function effectively reversed, has vastly lower activity, and its riboside is practically inactive. PMID:16591745

  8. Applicability of self-activation of an NaI scintillator for measurement of photo-neutrons around a high-energy X-ray radiotherapy machine.

    PubMed

    Wakabayashi, Genichiro; Nohtomi, Akihiro; Yahiro, Eriko; Fujibuchi, Toshioh; Fukunaga, Junichi; Umezu, Yoshiyuki; Nakamura, Yasuhiko; Nakamura, Katsumasa; Hosono, Makoto; Itoh, Tetsuo

    2015-01-01

    The applicability of the activation of an NaI scintillator for neutron monitoring at a clinical linac was investigated experimentally. Thermal neutron fluence rates are derived by measurement of the I-128 activity generated in an NaI scintillator irradiated by neutrons; ?-rays from I-128 are detected efficiently by the NaI scintillator. In order to verify the validity of this method for neutron measurement, we irradiated an NaI scintillator at a research reactor, and the neutron fluence rate was estimated. The method was then applied to neutron measurement at a 10-MV linac (Varian Clinac 21EX), and the neutron fluence rate was estimated at the isocenter and at 30 cm from the isocenter. When the scintillator was irradiated directly by high-energy X-rays, the production of I-126 was observed due to photo-nuclear reactions, in addition to the generation of I-128 and Na-24. From the results obtained by these measurements, it was found that the neutron measurement by activation of an NaI scintillator has a great advantage in estimates of a low neutron fluence rate by use of a quick measurement following a short-time irradiation. Also, the future application of this method to quasi real-time monitoring of neutrons during patient treatments at a radiotherapy facility is discussed, as well as the method of evaluation of the neutron dose. PMID:25404493

  9. Flow measurement by pulsed-neutron activation techniques at the PKL facility at Erlangen (Germany). [PWR

    SciTech Connect

    Kehler, P.

    1982-03-01

    Flow velocities in the downcomer at the PKL facility (in Erlangen, Germany) were measured by the Pulsed-Neutron Activation (PNA) techniques. This was the first time that a fully automated PNA system, incorporating a dedicated computer for on-line data reduction, was used for flow measurements. A prototype of a portable, pulsed, high-output neutron source, developed by the Sandia National Laboratories for the US Nuclear Regulatory Commission, was also successfully demonstrated during this test. The PNA system was the primary flow-measuring device used at the PKL, covering the whole range of velocities of interest. In this test series, the PKL simulated small-break accidents similar to the one that occurred at TMI. The flow velocities in the downcomer were, therefore, very low, ranging between 0.03 and 0.35 m/sec. Two additional flow-measuring methods were used over a smaller range of velocities. Wherever comparison was possible, the PNA-derived velocity values agreed well with the measurements performed by the two more conventional methods.

  10. DECOMPOSING STAR FORMATION AND ACTIVE GALACTIC NUCLEUS WITH SPITZER MID-INFRARED SPECTRA: LUMINOSITY FUNCTIONS AND CO-EVOLUTION

    SciTech Connect

    Fu Hai; Scoville, N. Z. [Astronomy Department, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Yan Lin [Spitzer Science Center, California Institute of Technology, MS 220-06, Pasadena, CA 91125 (United States); Capak, P. [Infrared Processing and Analysis Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125 (United States); Aussel, H.; Le Floc'h, E. [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Universite Paris Diderot, CE-Saclay, pt courrier 131, F-91191 Gif-sur-Yvette (France); Ilbert, O. [Laboratoire d'Astrophysique de Marseille, BP 8, Traverse du Siphon, 13376 Marseille Cedex 12 (France); Salvato, M. [IPP-Max-Planck-Institute for Plasma Physics, Boltzmannstrasse 2, D-85748, Garching (Germany); Kartaltepe, J. S. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85721 (United States); Frayer, D. T. [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944 (United States); Sanders, D. B. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Sheth, K. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Taniguchi, Y. [Research Center for Space and Cosmic Evolution, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577 (Japan)

    2010-10-10

    We present Spitzer 7-38 {mu}m spectra for a 24 {mu}m flux-limited sample of galaxies at z {approx} 0.7 in the COSMOS field. The detailed high-quality spectra allow us to cleanly separate star formation (SF) and active galactic nucleus (AGN) in individual galaxies. We first decompose mid-infrared luminosity functions (LFs). We find that the SF 8 {mu}m and 15 {mu}m LFs are well described by Schechter functions. AGNs dominate the space density at high luminosities, which leads to the shallow bright-end slope of the overall mid-infrared LFs. The total infrared (8-1000 {mu}m) LF from 70 {mu}m selected galaxies shows a shallower bright-end slope than the bolometrically corrected SF 15 {mu}m LF, owing to the intrinsic dispersion in the mid-to-far-infrared spectral energy distributions. We then study the contemporary growth of galaxies and their supermassive black holes (BHs). Seven of the thirty-one luminous infrared galaxies with Spitzer spectra host luminous AGNs, implying an AGN duty cycle of 23% {+-} 9%. The time-averaged ratio of BH accretion rate and SF rate matches the local M{sub BH} - M{sub bulge} relation and the M{sub BH} - M{sub host} relation at z {approx} 1. These results favor co-evolution scenarios in which BH growth and intense SF happen in the same event but the former spans a shorter lifetime than the latter. Finally, we compare our mid-infrared spectroscopic selection with other AGN identification methods and discuss candidate Compton-thick AGNs in the sample. While only half of the mid-infrared spectroscopically selected AGNs are detected in X-ray, {approx}90% of them can be identified with their near-infrared spectral indices.

  11. Determination of Copper by Neutron Activation Analysis in Conjunction with Compton Suppression Gamma Spectrometry

    SciTech Connect

    W. H. Zhang; A. Chatt

    2000-06-04

    Copper is considered to be an essential element. Its accurate determination in tissues, foods, and other biological materials is needed to study the effect of copper on human nutrition and health. Using and Advance Prediction Computer Program, it has been shown that short-lived {sup 66}Cu (half-life = 5.09 min) can be used to determine copper in biological materials by instrumental neutron activation analysis (INAA). However, it is seldom done in practice-in particular, for low copper content in high-salt biological materials-because of the Compton background interference from nuclides such as {sup 28}Al, {sup 38}Cl, and {sup 24}Na. To eliminate the Compton interference, a preconcentration NAA method has recently been developed in our laboratory using reversed-phase extraction chromatography of copper followed by short irradiation and conventional gamma-spectrometric counting of {sup 66}Cu; the detection limit is {approx}5 ppb.

  12. THERMAL NEUTRON ACTIVATION CROSS-SECTIONS FOR ISOMER PRODUCTION. PART II

    Microsoft Academic Search

    S. K. Mangal; P. S. Gill

    1963-01-01

    Thermal neutron activation cross sections were measured for the ; following cases. Hg¹⁹⁶(n gamma )Hg\\/sup 197m\\/, Hg¹⁹⁶(n gamma )Hg\\/su ; p 197\\/ Pt¹⁹⁴(n, gamma )Pt\\/sup 195m\\/, Pt¹⁹²(n, gamma )Pt\\/sup 193m\\/, Os\\/; sup 190\\/ (n, gg)Os\\/sup 191m\\/, Os¹⁹°(n gamma ) Os¹⁹¹, Er¹⁷°(n ; gamma )Er¹⁷¹, Pd¹¹°(n gamma )Pd\\/sup 111m\\/ Gd\\/su p 158\\/(n gamma )Gd\\/; sup 159\\/, Gd¹⁶° (n, gamma )Gd¹⁶¹, Ba¹³⁴

  13. Distribution of trace elements in the human body determined by neutron activation analysis.

    PubMed

    Yukawa, M; Amano, K; Suzuki-Yasumoto, M; Terai, M

    1980-01-01

    Neutron activation analysis and instrumental semiconductor gamma-ray spectrometry were used for analysis of 20 trace elements in 10 autopsied human organs and tissues (liver, kidney, cerebrum, cerebellum, heart, muscle, pancreas, spleen, lung, and aorta) from 63 Japanese persons, whose ages ranged from 15 days to 85 yr. Distributions of aluminum, bromine, magnesium, manganese, rubidium, selenium, and vanadium in human body were almost uniform. High concentrations of cadmium were found in kidney and liver samples. There was a high mercury concentration in the liver, kidney, and brain samples. Concentrations of other elements (arsenic, gold, cobalt, chromium, copper, iron, indium, antimony, selenium, titanium, and zinc) in each organ or tissue are also presented in this paper. PMID:7362268

  14. Neutron activation analysis on the surface of the Moon and other terrestrial planets

    NASA Astrophysics Data System (ADS)

    Golovin, Dmitry; Litvak, Maxim; Kozyrev, S. Alexander; Tretiyakov, Vladislav; Sanin, Anton; Vostrukhin, Andrey; Mitrofanov, Igor; Malakhov, Alexey

    Determine of elements composition of the planet subsurface in situ is important scientific task for understanding of origin and formation processes of terrestrial planets, moons and asteroids. Also this study will be very perspective in terms of utilization of mineral resources for future lunar base. Creation of such outpost will open doors for robotic and human exploration in the distant parts of Solar System. ADRON instrument onboard landing platforms Russian near-pole lunar missions (Glob and Resource) will be first example of using Neutron Activation method in space. It will measure nuclear composition of the lunar regolith in the landing sites up to 1 m depth. This instrument is able to use for different planets and conditions. For Venus surface, taking into account short lifetime of spacecraft one or two hours of operation will be enough to perform such measurements. Another good opportunity is using similar instrument on Lunar or Martian rovers for searching of important minerals.

  15. Analysis of low levels of rare earths by radiochemical neutron activation analysis

    USGS Publications Warehouse

    Wandless, G.A.; Morgan, J.W.

    1985-01-01

    A procedure for the radiochemical neutron-activation analysis for the rare earth elements (REE) involves the separation of the REE as a group by rapid ion-exchange methods and determination of yields by reactivation or by energy dispersive X-ray fluorescence (EDXRF) spectrometry. The U. S. Geological Survey (USGS) standard rocks, BCR-1 and AGV-1, were analyzed to determine the precision and accuracy of the method. We found that the precision was ??5-10% on the basis of replicate analysis and that, in general the accuracy was within ??5% of accepted values for most REE. Data for USGS standard rocks BIR-1 (Icelandic basalt) and DNC-1 (North Carolina diabase) are also presented. ?? 1985 Akade??miai Kiado??.

  16. Evaluation of trace elements in lung samples from coal miners using neutron activation analysis.

    PubMed

    Saiki, M; Saldiva, P H; Alice, S H

    1999-01-01

    In this study, instrumental neutron activation analysis was applied to the determination of Sc, La, Ce, Nd, Sm, Eu, Tb, Yb, Lu, Hf, Th, and U in lung samples from miners working in coal mines located in the state of Santa Catarina, Brazil. These results were compared to those from a control group constituted of healthy individuals. The results showed that the elements determined exhibit considerable intersubject variability within a single group of individuals and the mean values of concentrations in miners' lungs were higher than those of normal individuals. Lung samples presented U concentrations varying from 11 to 890 micrograms/kg. Therefore, for some samples, the contribution of the uranium fission products in the analysis of La, Ce, Nd, and Sm was considered by determining the interference correction factors. The accuracy of the results was evaluated by analyzing certified reference materials. PMID:10676503

  17. Instrumental neutron activation analysis data for cloud-water particulate samples, Mount Bamboo, Taiwan

    USGS Publications Warehouse

    Lin, Neng-Huei; Sheu, Guey-Rong; Wetherbee, Gregory A.; Debey, Timothy M.

    2013-01-01

    Cloud water was sampled on Mount Bamboo in northern Taiwan during March 22-24, 2002. Cloud-water samples were filtered using 0.45-micron filters to remove particulate material from the water samples. Filtered particulates were analyzed by instrumental neutron activation analysis (INAA) at the U.S. Geological Survey National Reactor Facility in Denver, Colorado, in February 2012. INAA elemental composition data for the particulate materials are presented. These data complement analyses of the aqueous portion of the cloud-water samples, which were performed earlier by the Department of Atmospheric Sciences, National Central University, Taiwan. The data are intended for evaluation of atmospheric transport processes and air-pollution sources in Southeast Asia.

  18. Investigation of therapeutic potentials of some selected medicinal plants using neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Abubakar, Sani; Usman, Ahmed Rufa'i.; Isa, Nasiru Fage; Khandaker, Mayeen Uddin; Abubakar, Nuraddeen

    2015-04-01

    Series of attempts were made to investigate concentrations of trace elements and their therapeutic properties in various medicinal plants. In this study, samples of some commonly used plants were collected from Bauchi State, Nigeria. They includes leaves of azadirachta indica (neem), Moringa Oleifera (moringa), jatropha curcas (purgin Nut), guiera senegalensis (custard apple) and anogeissus leiocarpus (African birch). These samples were analyzed for their trace elements contents with both short and long irradiation protocols of Instrumental Neutron Activation Analysis (INAA) at Nigerian Research Reactor-1 (NIRR-1) of Ahmadu Bello University, Zaria, Nigeria. The level of trace elements found varies from one sample to another, with some reported at hundreds of mg/Kg dry weight. The results have been compared with the available literature data. The presence of these trace elements indicates promising potentials of these plants for relief of certain ailments.

  19. Probabilistic Analysis and Non-Linear SemiActive Base Isolation Spectra for Aseismic Design

    Microsoft Academic Search

    J. G. Chase; G. W. Rodgers; K. J. Mulligan; J. B. Mander; R. P. Dhakal

    Semi-active resetable actuators can significantly improve seismic structural response and customise structural hysteresis loops using novel devices. However, no one has yet examined their use as base isolators despite recent results that show the hysteretic (force- displacement) response for optimally controlled base isolation stiffness is similar to a novel 1-3 resetable device response, particularly if including non-ideal, realistic non- linearities

  20. Estimation of Performance of an Active Well Coincidence Counter Equipped with Boron-Coated Straw Neutron Detectors - 13401

    SciTech Connect

    Young, B.M. [Canberra Industries, Inc., 800 Research Parkway, Meriden, CT 06450 (United States)] [Canberra Industries, Inc., 800 Research Parkway, Meriden, CT 06450 (United States); Lacy, J.L.; Athanasiades, A. [Proportional Technologies, Inc., 8022 El Rio Street, Houston, TX 77054 (United States)] [Proportional Technologies, Inc., 8022 El Rio Street, Houston, TX 77054 (United States)

    2013-07-01

    He-3, a very rare isotope of natural helium gas, has ideal properties for the detection of thermal neutrons. As such it has become the standard material for neutron detectors and sees ubiquitous use within many radiometric applications that require neutron sensitivity. Until recently, there has been a fairly abundant supply of He-3. However, with the reduction in nuclear weapons, production of tritium ceased decades ago and the stockpile has largely decayed away, reducing the available He-3 supply to a small fraction of that needed for neutron detection. A suitable and rapidly-deployable replacement technology for neutron detectors must be found. Many potential replacement technologies are under active investigation and development. One broad class of technologies utilizes B-10 as a neutron capture medium in coatings on the internal surfaces of proportional detectors. A particular implementation of this sort of technology is the boron-coated 'straw' (BCS) detectors under development by Proportional Technologies, Inc. (PTi). This technology employs a coating of B-10 enriched boron carbide (B{sub 4}C) on the inside of narrow tubes, roughly 4 mm in diameter. A neutron counter (e.g. a slab, a well counter, or a large assay counter designed to accommodate 200 liter drums) could be constructed by distributing these narrow tubes throughout the polyethylene body of the counter. One type of neutron counter that is of particular importance to safeguards applications is the Active Well Coincidence Counter (AWCC), which is a Los Alamos design that traditionally employs 42 He-3 detectors. This is a very flexible design which can accurately assay small samples of uranium- and plutonium-bearing materials. Utilizing the MCNPX code and benchmarking against measurements where possible, the standard AWCC has been redesigned to utilize the BCS technology. Particular aspects of the counter performance include the single-neutron ('singles') detection efficiency and the time constant for the decrease in neutron population in the counter following a fission event (a.k.a. the die-away time). Results of the modeling and optimization are presented. (authors)

  1. The structure, methyl rotation reflected in inelastic and quasielastic neutron scattering and vibrational spectra of 1,2,3,5-tetramethoxybenzene and its 2:1 complex with 1,2,4,5-tetracyanobenzene.

    PubMed

    Pawlukoj?, Andrzej; Prager, Michael; Dobrowolska, Wanda Sawka; Bator, Grazyna; Sobczyk, Lucjan; Ivanov, Alexander; Rols, Stéphane; Grech, Eugeniusz; Nowicka-Scheibe, Joanna; Unruh, Tobias

    2008-10-21

    X-ray diffraction studies show that molecules of the 1,2,3,5-tetramethoxybenzene (TMOB)(2) x 1,2,4,5-tetracyanobenzene complex form ...CCDCCDCC... columns with the short distances between molecular planes of C and D molecules equal to 3.186 A. The vibrational spectra recorded by using the inelastic neutron scattering, Raman, IR, and quasielastic neutron scattering (QENS) techniques aided by density functional theory calculations for the isolated molecules and the crystalline state enabled all four inequivalent librational modes, ascribed to the methoxy groups, to be analyzed. A rather good consistency was found between the experimental frequencies and those calculated for the crystal. The consistency was also achieved between the experimental structure of molecules and the theoretically reproduced one. A close similarity of the structures of the TMOB molecule isolated and in the complex is taken as a sign of dominating intramolecular interaction. The QENS spectra contain three Lorentzians of relative intensities of 1:1:2. Thus the two most strongly hindered of the four inequivalent methoxy groups in the crystalline lattice are characterized by rather similar barrier heights in good agreement with the packing analysis. PMID:19045208

  2. COHN analysis: Body composition measurements based on the associated particle imaging and prompt-gamma neutron activation analysis techniques

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The measurement of the body's carbon (C), oxygen (O), hydrogen (H), and nitrogen (N) content can be used to calculate the relative amounts of fat, protein, and water. A system based on prompt-gamma neutron activation analysis (PGNAA), coupled with the associated particle imaging (API) technique, is...

  3. Assessment of the associated particle prompt gamma neutron activation technique for total body nitrogen measurement in vivo

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Total Body Nitrogen (TBN) can be used to estimate Total Body Protein (TBP), an important body composition component at the molecular level. A system using the associated particle technique in conjunction with prompt gamma neutron activation analysis has been developed for the measurement of TBN in ...

  4. NEUTRON ACTIVATION ANALYSIS FOR SIMULTANEOUS DETERMINATION OF TRACE ELEMENTS IN AMBIENT AIR COLLECTED ON GLASS-FIBER FILTERS

    EPA Science Inventory

    Arsenic with 25 other elements are simultaneously determined in ambient air samples collected on glass-fiber filter composites at 250 United States sites. The instrumental neutron activation analysis (NAA) technique combined with the power of a dedicated mini-computer resulted in...

  5. Analysis of essential elements in Pragya-peya—a herbal drink and its constituents by neutron activation

    Microsoft Academic Search

    A. Kumar; A. G. C. Nair; A. V. R. Reddy; A. N. Garg

    2005-01-01

    Ayurvedic herbal formulations are a good source of several nutrient elements essential for metabolic processes. Pragya-peya, a herbal drink and its 12 herbal constituents have been analyzed for 7 minor (Al, Ca, Cl, Mg, Na, K, P) and 15 trace (Ba, Br, Co, Cr, Cs, Fe, Hg, La, Mn, Rb, Sc, Se, Th, V, Zn) elements by instrumental neutron activation

  6. Instrumental neutron activation analysis of rocks and rock-forming minerals by using Ge(Li) detectors and a computer

    Microsoft Academic Search

    E. M. Lobanov; Yu. A. Levushkin; S. P. Vlasyuga

    1973-01-01

    The practical and theoretical necessity of more complete knowledge of the chemical elements in natural formations and the widespread introduction of mathematical statistics methods and the interpretation of the results of geochemical research [1, 2] require increasing the sensitivity and accuracy of analytic procedures [3]. In this respect themost reliable and promising is neutron activation analysis [4]. The simultaneous determination

  7. ANALYSIS OF TRACE ELEMENTS IN POWER PLANT AND INDUSTRIAL INCINERATOR FLY ASHES BY INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS (INAA)

    Microsoft Academic Search

    Wadeeah M. Al-Areqi; Amran Ab; Sukiman Sarmani

    An elemental analysis of fly ash samples from Selangor & Perak coal-fired power plants and an industrial incinerator from Negeri Sembilan were carried out using instrumental neutron activation analysis (INAA). All samples were irradiated at the Malaysian Nuclear Agency laboratory PUSPATI Reactor for 6 hours and later counted at the Nuclear Science Program, UKM using an HPGe detector with a

  8. Studies on osteoporosis. V. Comparison of methods of evaluation of osteoporosis and study of chromosome changes induced by neutron activation

    SciTech Connect

    Robin, J.C.; Sirianni, S.R.; Pragay, D.A.; Ambrus, J.L.

    1981-01-01

    In vivo activation analysis was compared with ashing and atomic absorption spectrophotometry for the determination of total skeletal calcium content in mice. The results were close to identical. The possible mutagenic-carcinogenic effect of repeated exposure to whole body neutron irradiation was studied by chromosome analysis. Under the conditions of these experiments, no significant chromosome changes were seen.

  9. Thermodynamic analysis of spectra

    NASA Astrophysics Data System (ADS)

    Mitchell, G. E.; Shriner, J. F.

    2008-04-01

    Although random matrix theory had its initial application to neutron resonances, there is a relative scarcity of suitable nuclear data. The primary reason for this is the sensitivity of the standard measures used to evaluate spectra—the spectra must be essential pure (no state with a different symmetry) and complete (no states missing). Additional measures that are less sensitive to these experimental limitations are of significant value. The standard measure for long range order is the ?3 statistic. In the original paper that introduced this statistic, Dyson and Mehta also attempted to evaluate spectra with thermodynamic variables obtained from the circular orthogonal ensemble. We consider the thermodynamic "internal energy" and evaluate its sensitivity to experimental limitations such as missing and spurious levels. Monte Carlo simulations suggest that the internal energy is less sensitive to mistakes than is ?3, and thus the internal energy can serve as a addition to the tool kit for evaluating experimental spectra.

  10. 14.8 MeV neutron activation cross-section measurements of a few tellurium isotopes

    Microsoft Academic Search

    N. K. Majumdar; A. Chatterjee

    1963-01-01

    The activation cross sections of the (n,2n) and (n, alpha ) products of ; different tellurium isotopes for 14.8-Mev neutrons are measured. Enriched ; isotopes are used to determine the (n,2n) cross sections of the 9.36-hr Te\\/sup ; 127\\/, 67.5min Te¹²⁹, and 33-day Te¹²⁹ activities relative to the Al ; (n p)Mg²⁷ cross section. By means of chemical separation, the

  11. Thermal neutron activation cross sections for the isomeric states in odd indium isotopes and the j-selection rule

    Microsoft Academic Search

    K. F. Alexander; H. F. Brinckmann; C. Heiser; W. Neubert

    1968-01-01

    The thermal neutron activation cross sections for the two isomeric states in 114In were measured using a 2pi flow counter for the long-lived and the pulsed activation method for the short-lived isomer. The values obtained are sigmaact = 7.5+\\/-0.7 b for 114m1In (49 d) in agreement with a value measured by Keisch, and sigmaact = 3.1-0.7+0.4 b for 114m2In (42

  12. Instrumental activation analysis of coal and fly ash with thermal and epithermal neutrons and short-lived nuclides

    USGS Publications Warehouse

    Steinnes, E.; Rowe, J.J.

    1976-01-01

    Instrumental neutron activation analysis is applied to the determination of about 25 elements in coals and fly ash by means of nuclides with half-lives of less than 48 h ; thermal and epithermal irradiations are used. The results indicate that epithermal activation is preferable for twelve of the elements (Ga, As, Br, Sr, In, Cs, Ba, La, Sm, Ho, W and U). Data for SRM 1632 (coal) and SRM 1633 (fly ash) compare favorably with the results obtained by other investigators. ?? 1976.

  13. Comparison of the role of photon and neutron activation analyses for elemental characterization of geological, biological and environmental materials

    Microsoft Academic Search

    Z. ?anda; J. Ku?era; J. Mizera; J. Frána

    2007-01-01

    The potential of photon activation analysis (PAA) for multielement trace analysis can hardly compare with that of neutron\\u000a activation analysis (NAA). However, PAA appears superior over NAA for the determination of a number of elements, namely C,\\u000a N, O, F, Mg, Si, Ca, Ti, Ni, Sr, Y, Zr, Nb, Sn, Tl and Pb in geological, environmental and biological materials. Most

  14. Neutron-induced 63Ni activity and microscopic observation of copper samples exposed to the Hiroshima atomic bomb

    NASA Astrophysics Data System (ADS)

    Shizuma, Kiyoshi; Endo, Satoru; Shinozaki, Kenji; Fukushima, Hiroshi

    2013-05-01

    Fast neutron activation data for 63Ni in copper samples exposed to the Hiroshima atomic bomb are important in evaluating neutron doses to the survivors. Up to until now, accelerator mass spectrometry and liquid scintillation counting methods have been applied in 63Ni measurements and data were accumulated within 1500 m from the hypocenter. The slope of the activation curve versus distance shows reasonable agreement with the calculation result, however, data near the hypocenter are scarce. In the present work, two copper samples obtained from the Atomic bomb dome (155 m from the hypocenter) and the Bank of Japan building (392 m) were utilized in 63Ni beta-ray measurement with a Si surface barrier detector. Additionally, microscopic observation of the metal surfaces was performed for the first time. Only upper limit of 63Ni production was obtained for copper sample of the Atomic bomb dome. The result of the 63Ni measurement for Bank of Japan building show reasonable agreement with the AMS measurement and to fast neutron activation calculations based on the Dosimetry System 2002 (DS02) neutrons.

  15. Unconventional neutron sources for oil well logging

    NASA Astrophysics Data System (ADS)

    Frankle, C. M.; Dale, G. E.

    2013-09-01

    Americium-Beryllium (AmBe) radiological neutron sources have been widely used in the petroleum industry for well logging purposes. There is strong desire on the part of various governmental and regulatory bodies to find alternate sources due to the high activity and small size of AmBe sources. Other neutron sources are available, both radiological (252Cf) and electronic accelerator driven (D-D and D-T). All of these, however, have substantially different neutron energy spectra from AmBe and thus cause significantly different responses in well logging tools. We report on simulations performed using unconventional sources and techniques to attempt to better replicate the porosity and carbon/oxygen ratio responses a well logging tool would see from AmBe neutrons. The AmBe response of these two types of tools is compared to the response from 252Cf, D-D, D-T, filtered D-T, and T-T sources.

  16. Constraining black hole masses in low-accreting active galactic nuclei using X-ray spectra

    NASA Astrophysics Data System (ADS)

    Jang, I.; Gliozzi, M.; Hughes, C.; Titarchuk, L.

    2014-09-01

    In a recent work we demonstrated that a novel X-ray scaling method, originally introduced for Galactic black holes (BHs), can be reliably extended to estimate the mass of supermassive BHs accreting at a moderate to high level. Here we investigate the limits of applicability of this method to low-accreting active galactic nuclei (AGN), using a control sample with good-quality X-ray data and dynamically measured mass. For low-accreting AGN (LX/LEdd ? 10-4), because the basic assumption that the photon index positively correlates with the accretion rate no longer holds the X-ray scaling method cannot be used. Nevertheless, the inverse correlation in the ?-LX/LEdd diagram, found in several low-accreting BHs and confirmed by this sample, can be used to constrain MBH within a factor of ˜10 from the dynamically determined values. We provide a simple recipe to determine MBH using solely X-ray spectral data, which can be used as a sanity check for MBH determination based on indirect optical methods.

  17. Comparative mutagenicity of halomethanes and halonitromethanes in Salmonella TA100: structure-activity analysis and mutation spectra.

    PubMed

    Kundu, Bijit; Richardson, Susan D; Granville, Courtney A; Shaughnessy, Daniel T; Hanley, Nancy M; Swartz, Paul D; Richard, Ann M; DeMarini, David M

    2004-10-01

    Halonitromethanes (HNMs) are a recently identified class of disinfection by-products (DPBs) in drinking water that are mutagenic in Salmonella and potent inducers of DNA strand breaks in mammalian cells. Here we compared the mutagenic potencies of the HNMs to those of their halomethane (HM) homologues by testing all nine HNMs and seven of the nine HMs (minus bromomethane and chloromethane) under the same conditions (the pre-incubation assay) in Salmonella TA100 +/- S9. We also determined the mutation spectra for several DBPs. In the presence of S9, all nine HNMs, but only three HMs, dibromomethane (DBM), dichloromethane (DCM), and bromochloromethane (BCM), were mutagenic. Only two DBPs of each class were mutagenic in the absence of S9. The HNMs were generally more potent mutagens than their HM homologues, and the brominated forms of both classes of DBPs were more mutagenic and cytotoxic than their chlorinated homologues. The HNMs were at least 10 times more cytotoxic than the HMs, and the cytotoxicity rankings in the presence of S9 were similar for the HNMs and the HMs. The addition of a nitro-group to BCM did not change the mutation spectra significantly, with both homologues inducing primarily (55-58%) GC --> AT transitions. The greater cytotoxic and mutagenic activities of the HNMs relative to the HMs are likely due to the greater intrinsic reactivity conferred by the nitro-group. Energy calculations predicted increased reactivity with increasing bromination and greater reactivity of the HNMs versus the HMs (Elumo values were approximately 20 kcal/mol lower for the HNMs compared to their HM homologues). Given that the HNMs also are potent genotoxins in mammalian cells [Environ. Sci. Technol. 38 (2004) 62] and are more mutagenic and 10x more cytotoxic in Salmonella than the HMs, whose levels are regulated in drinking water, further study of their occurrence and potential health effects is warranted. PMID:15450430

  18. A VLBA SEARCH FOR BINARY BLACK HOLES IN ACTIVE GALACTIC NUCLEI WITH DOUBLE-PEAKED OPTICAL EMISSION LINE SPECTRA

    SciTech Connect

    Tingay, S. J.; Wayth, R. B., E-mail: s.tingay@curtin.edu.au [International Centre for Radio Astronomy Research, Curtin University, Bentley, WA (Australia)

    2011-06-15

    We have examined a subset of 11 active galactic nuclei (AGNs) drawn from a sample of 87 objects that possess double-peaked optical emission line spectra, as put forward by Wang et al. and are detectable in the Faint Images of the Radio Sky at Twenty-centimeters (FIRST) survey at radio wavelengths. The double-peaked nature of the optical emission line spectra has been suggested as evidence for the existence of binary black holes in these AGNs, although this interpretation is controversial. We make a simple suggestion that direct evidence of binary black holes in these objects could be searched for in the form of dual sources of compact radio emission associated with the AGNs. To explore this idea, we have used the Very Long Baseline Array to observe these 11 objects from the Wang et al. sample. Of the 11 objects, we detect compact radio emission from two, SDSS J151709+335324 and SDSS J160024+264035. Both objects show single components of compact radio emission. The morphology of SDSS J151709+335324 is consistent with a recent comprehensive multi-wavelength study of this object by Rosario et al. Assuming that the entire sample consists of binary black holes, we would expect of order one double radio core to be detected, based on radio wavelength detection rates from FIRST and very long baseline interferometry surveys. We have not detected any double cores, thus this work does not substantially support the idea that AGNs with double-peaked optical emission lines contain binary black holes. However, the study of larger samples should be undertaken to provide a more secure statistical result, given the estimated detection rates.

  19. A benchmarked MCNP model of the in vivo detection of gadolinium by prompt gamma neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Gräfe, J. L.; McNeill, F. E.; Byun, S. H.; Chettle, D. R.; Noseworthy, M. D.

    2010-08-01

    Gadolinium (Gd)-based contrast agents are a valuable diagnostic aid for magnetic resonance imaging (MRI). The amount of free Gd deposited in tissues following contrast enhanced MRI is of toxicological concern. The McMaster University in vivo prompt gamma neutron activation analysis facility has been adapted for the detection of Gd in the kidney, liver, and the leg muscle. A simple model of the HPGe detector used for detection of the prompt ?-rays following Gd neutron capture has been created using Monte Carlo simulation. A separate simulation describing the neutron collimation and shielding apparatus has been modified to determine the neutron capture rate in the Gd phantoms. The MCNP simulation results have been confirmed by experimental measurement. The deviations between MCNP and the experiment were between 1% and 18%, with an average deviation of 3.8 ± 6.7%. The validated MCNP model is to be used to improve the Gd in vivo measurement sensitivity by determining the best neutron moderator/reflector arrangement.

  20. Neutrons in the low-background Ge-detector vicinity estimated from different activation reactions.

    PubMed

    Jovan?evi?, N; Krmar, M

    2011-03-01

    Neutrons produced by cosmic-ray muons in a detector shield and other surrounding materials can be captured or scattered by different nuclei in subsequent reactions. The gamma photons emitted after nuclear capture or scattering from produced Ge isotopes are used to estimate the neutron flux. If a bulk sample measured in some low background gamma spectroscopy system contains hydrogen, a high energy photon (of energy 2223keV) emitted in the process of deuterium production can be used to estimate the flux of thermal neutrons. Results obtained from the interaction of neutrons with H as well as with some Ge isotopes are computed and compared in this paper. The passive lead shield in a detector system is a source of a significant fraction of the gamma radiation induced by capture and inelastic scattering of neutrons. We also used gamma lines emitted by several Pb isotopes to estimate the neutron flux near a detector. PMID:21193316