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Sample records for absolute neutron activation

  1. Prospects for absolute neutron activation analysis

    The desirability for absolute neutron activation analysis(ANAA) is two-fold. Results by the comparitor method are only as good as the standards used, and also the method offers a chance of having the final results available within minutes of completing the analysis. In the past ANAA was not seriously considered because of the scarcity and poor qaulity of the nuclear data that were available. This situation is however steadily improving and the possible applications are being investigated. This report reviews the present status by considering the basic activation equation, calculation of parameters, the factors of importance and the size error one might expect

  2. Absolute technique for neutron source calibration by radiation induced activity

    The neutron yield from a Radium Beryllium neutron source has been determined experimentally by the induced Mn-56 activity. The neutron source was placed in the center of a tank filled with aqueous manganese sulphate (MnSO4) solution. Irradiation time usually lasted about 16-18 hours in order to secure saturation. The average induced Mn-56 activity within the MnSO4 bath was then measured by the use of NaI scintillation detector. This detector was placed in a sealed aluminum jacket at the center of the tank. This detector was connected with the necessary electronic counting system and was pre calibrated against a 4 πβ-γ coincidence counting system. The efficiency of the NaI counting system as a function of MnSO4 solution density is investigated as well as the proper dimension of the used tank for the sake of calibration purposes. The neutron leakage within the MnSO4 baths was also investigated for different dimensions of tanks. The experimental errors involved in the counting system were also considered. The numerical value of neutron yield from the used radium beryllium neutron source was given with its corresponding statistical errors as (1.10 + 0.065) x 106 neutron per second

  3. Absolute measurement of β activities and application to the determination of neutronic densities

    M. Berthelot, to my entrance to the ''Commissariat a l 'Energie Atomique'', proposed me to study the absolute measurement of neutron densities. Very quickly the problem of the absolute activity of β sources became the central object of this work. In a first part, we will develop the methods of absolute determination for β activities. The use of a 4π counter permits to get the absolute activity of all beta radioactive source, susceptible to be put as thin leaf and of period superior than some minutes. The method is independent of the spectra of the measured radioelement. we will describe in the second part some applications which use neutron densities measurement, neutron sources intensities and ratio of cross sections of capture of thermal neutrons. (M.B.)

  4. Absolute calibration method for laser megajoule neutron yield measurement by activation diagnostics.

    Landoas, Olivier; Glebov, Vladimir Yu; Rossé, Bertrand; Briat, Michelle; Disdier, Laurent; Sangster, Thomas C; Duffy, Tim; Marmouget, Jean Gabriel; Varignon, Cyril; Ledoux, Xavier; Caillaud, Tony; Thfoin, Isabelle; Bourgade, Jean-Luc

    2011-07-01

    The laser megajoule (LMJ) and the National Ignition Facility (NIF) plan to demonstrate thermonuclear ignition using inertial confinement fusion (ICF). The neutron yield is one of the most important parameters to characterize ICF experiment performance. For decades, the activation diagnostic was chosen as a reference at ICF facilities and is now planned to be the first nuclear diagnostic on LMJ, measuring both 2.45 MeV and 14.1 MeV neutron yields. Challenges for the activation diagnostic development are absolute calibration, accuracy, range requirement, and harsh environment. At this time, copper and zirconium material are identified for 14.1 MeV neutron yield measurement and indium material for 2.45 MeV neutrons. A series of calibrations were performed at Commissariat à l'Energie Atomique (CEA) on a Van de Graff facility to determine activation diagnostics efficiencies and to compare them with results from calculations. The CEA copper activation diagnostic was tested on the OMEGA facility during DT implosion. Experiments showed that CEA and Laboratory for Laser Energetics (LLE) diagnostics agree to better than 1% on the neutron yield measurement, with an independent calibration for each system. Also, experimental sensitivities are in good agreement with simulations and allow us to scale activation diagnostics for the LMJ measurement range. PMID:21806179

  5. Experimental and Monte-Carlo absolute efficiency calibration of HPGE γ-ray spectrometer for application in neutron activation analysis

    High Purity Germanium (HPGe) detector is widely used to measure the γ-rays from neutron activated foils used for neutron spectra measurement due to its better energy resolution and photopeak efficiency. To determine the neutron induced activity in foils, it is very important to carry out absolute calibration for photo-peak efficiency in a wide range of γ-ray energy.Neutron activated foils are considered as extended γ-ray sources. The sources available for efficiency calibration are usually point sources. Therefore it is difficult to determine the photo-peak efficiency for extended sources using these point sources. A method has been developed to address this problem. This method is a combination of experimental measurement with point sources and development of an optimized model for Monte-Carlo N-Particle Code (MCNP) with the help of these experimental measurements. This MCNP model then can be used to find the photo-peak efficiency for any kind of source at any energy. (author)

  6. Absolute neutronic performance of SNS from gold foil application

    The determination of absolute neutron fluxes by white beam activation of thick gold foils in conjuction with spectral analysis by time-of-flight monitors is described. A numerical integration procedure is presented and the method applied to determining the absolute performance of SNS from data obtained during the initial commissioning run in December 1984. (author)

  7. Absolute measurements of fast neutrons using yttrium

    Yttrium is presented as an absolute neutron detector for pulsed neutron sources. It has high sensitivity for detecting fast neutrons. Yttrium has the property of generating a monoenergetic secondary radiation in the form of a 909 keV gamma-ray caused by inelastic neutron interaction. It was calibrated numerically using MCNPX and does not need periodic recalibration. The total yttrium efficiency for detecting 2.45 MeV neutrons was determined to be fn∼4.1x10-4 with an uncertainty of about 0.27%. The yttrium detector was employed in the NX2 plasma focus experiments and showed the neutron yield of the order of 108 neutrons per discharge.

  8. Absolute measurement of {beta} activities and application to the determination of neutronic densities; Mesure absolue d'activites {beta} et application a la determination des densites neutronique

    Cohen, R. [Commissariat a l' Energie Atomique, Lab. du Fort de Chatillon, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1951-01-15

    M. Berthelot, to my entrance to the ''Commissariat a l 'Energie Atomique'', proposed me to study the absolute measurement of neutron densities. Very quickly the problem of the absolute activity of {beta} sources became the central object of this work. In a first part, we will develop the methods of absolute determination for {beta} activities. The use of a 4{pi} counter permits to get the absolute activity of all beta radioactive source, susceptible to be put as thin leaf and of period superior than some minutes. The method is independent of the spectra of the measured radioelement. we will describe in the second part some applications which use neutron densities measurement, neutron sources intensities and ratio of cross sections of capture of thermal neutrons. (M.B.) [French] M. Berthelot, a mon entree au ''Commissariat a l 'Energie Atomique'', m'a propose d'etudier la mesure absolue des densites neutroniques. Tres rapidement le probleme de l'activite absolue des sources beta est devenu l'objet central de ce travail. Dans une premiere partie, on abordera les methodes de determination absolue des activites beta. L'utilisation d'un compteur 4{pi} permet d 'obtenir l'activite absolue de toute source radioactive beta, susceptible d'etre mise sous forme de feuille mince et de periode superieure a quelques minutes. La methode est independante du spectre du radioelement mesure. On decrira dans la seconde partie quelques applications a des mesures de densites neutroniques, d'intensites de sources de neutrons et de rapport de sections efficaces de capture de neutrons thermiques. (M.B.)

  9. Strategy for the absolute neutron emission measurement on ITER

    Accuracy of 10% is demanded to the absolute fusion measurement on ITER. To achieve this accuracy, a functional combination of several types of neutron measurement subsystem, cross calibration among them, and in situ calibration are needed. Neutron transport calculation shows the suitable calibration source is a DT/DD neutron generator of source strength higher than 1010 n/s (neutron/second) for DT and 108 n/s for DD. It will take eight weeks at the minimum with this source to calibrate flux monitors, profile monitors, and the activation system.

  10. Absolute measurements of the thermal neutron flux by the foil activation method using the 4πβ-γ coincidence technique

    An analysis of the correction factors required for the β-γ coincidence method is presented together with a listing of the various formulae involved in the determination of radioactive sources. The detection system including the activation detectores are described and the results are shown for the absolute measurements of thermal neutron flux carried out in the core of the Argonaut Reactor, at Instituto de Engenharia Nuclear (IEN), Brazil. (Author)

  11. A method to determine the absolute neutron output of small D-T neutron generators

    We propose a standard method of establishing the absolute neutron output from small, D-T, 14 MeV neutron generators. This method uses a copper activation measurement in a configuration that we have calibrated with fission ionization chambers from NIST. The absolute uncertainty in this calibration is less than ± 7%. The copper activation method is insensitive to backgrounds from low energy scattered neutrons because it uses the 63Cu(n, 2n)62Cu reaction which has a 12 MeV threshold. With this calibration method, measurements of absolute neutron output are possible under a variety of experimental conditions, including those simulating nuclear well logging. In addition, the configuration of the copper samples that we propose gives high counting rates so that the statistical precision of the measurement of neutron output, depending upon the generator voltage and beam current, is on the order of 1%. (orig.)

  12. Comparison of two semi-absolute methods. k0-instrumental neutron activation analysis and fundamental parameter method X-ray fluorescence spectrometry for Ni-based alloys

    Nickel based alloys play important role in nuclear, mechanical and chemical industry. Two semi-absolute standardless methods, k0-instrumental neutron activation analysis (k0-INAA) and fundamental parameter X-ray fluorescence spectrometry (FP-XRF) were used for the characterization of certified nickel based alloys. The optimized experimental conditions for NAA provided results for 18 and XRF for 15 elements. Both techniques were unable to quantify some important alloy making elements. However, both reported results of other elements as information values. The techniques were analyzed for their sensitivity and accuracy. Sensitivity was evaluated by the number of elements determined by each technique. Accuracy was ascertained by using the linear regression analysis and the average root mean squared error.

  13. A development and integration of the concentration database for relative method, k0 method and absolute method in instrumental neutron activation analysis using Microsoft Access

    Instrumental Neutron Activation Analysis (INAA) is offen used to determine and calculate the concentration of an element in the sample by the National University of Malaysia, especially students of Nuclear Science Program. The lack of a database service leads consumers to take longer time to calculate the concentration of an element in the sample. This is because we are more dependent on software that is developed by foreign researchers which are costly. To overcome this problem, a study has been carried out to build an INAA database software. The objective of this study is to build a database software that help the users of INAA in Relative Method and Absolute Method for calculating the element concentration in the sample using Microsoft Excel 2010 and Microsoft Access 2010. The study also integrates k0 data, k0 Concent and k0-Westcott to execute and complete the system. After the integration, a study was conducted to test the effectiveness of the database software by comparing the concentrations between the experiments and in the database. Triple Bare Monitor Zr-Au and Cr-Mo-Au were used in Abs-INAA as monitor to determine the thermal to epithermal neutron flux ratio (f). Calculations involved in determining the concentration are the net peak area (Np), the measurement time (tm), the irradiation time (tirr), k-factor (k), thermal to epithermal neutron flux ratio (f), the parameters of the neutron flux distribution epithermal (α) and detection efficiency (εp). For Com-INAA databases, reference material IAEA-375 Soil was used to calculate the concentration of elements in the sample. CRM, SRM are also used in this database. After the INAA database integration, a verification process was to examine the effectiveness of the Abs-INAA was carried out by comparing the sample concentration between the in database and the experiment. The result of the experimental concentration value of INAA database software performed with high accuracy and precision. ICC

  14. An associated particle technique for absolute neutron counting efficiency determination

    The 7Li(p,n)7Be reaction has been used to produce neutrons with energies ranging from 8 to 13 MeV in order to measure the absolute neutron counting efficiency of a large NE213 scintillator by the associated particle method. Recoil 7Be nuclei were detected with a ΔE(gas)-E (solid) telescope in coincidence with neutrons. The method is suitable for neutron energies greater than 1.2MeV and could be applied to establish the neutron efficiency response of any detector

  15. Absolute cross-section normalization of magnetic neutron scattering data

    Xu, Guangyong; Xu, Zhijun; Tranquada, J. M.

    2013-01-01

    We discuss various methods to obtain the resolution volume for neutron scattering experiments, in order to perform absolute normalization on inelastic magnetic neutron scattering data. Examples from previous experiments are given. We also try to provide clear definitions of a number of physical quantities which are commonly used to describe neutron magnetic scattering results, including the dynamic spin correlation function and the imaginary part of the dynamic susceptibility. Formulas that c...

  16. Measuring the absolute DT neutron yield using the Magnetic Recoil Spectrometer at OMEGA and the NIF

    A Magnetic Recoil Spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion (ICF) implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.

  17. Measuring the absolute DT neutron yield using the Magnetic Recoil Spectrometer at OMEGA and the NIF

    Mackinnon, A; Casey, D; Frenje, J A; Johnson, M G; Seguin, F H; Li, C K; Petrasso, R D; Glebov, V Y; Katz, J; Knauer, J; Meyerhofer, D; Sangster, T; Bionta, R; Bleuel, D; Hachett, S P; Hartouni, E; Lepape, S; Mckernan, M; Moran, M; Yeamans, C

    2012-05-03

    A Magnetic Recoil Spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion (ICF) implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.

  18. Absolute Neutron Fluence Measurements at the NIST Center for Neutron Research

    Yue, A.; Dewey, M.; Gilliam, D.; Nico, J.; Anderson, E.; Snow, M.; Greene, G.; Laptev, A.

    2015-10-01

    Precise, absolute fluence measurements of cold and thermal neutron beams are of primary importance to beam-type determinations of the neutron lifetime, measurements of standard neutron cross sections, and the development of standards for neutron dosimetry. At the National Institute of Standards and Technology (NIST), a totally absorbing neutron detector based on absolute counting of the 10B(n,α1)7Li reaction 478 keV gamma ray has been used to perform fluence measurements with a precision of 0.06%. This detector has been used to improve the neutron fluence determination in the 2000 NIST beam neutron lifetime by a factor of five, significantly reducing the uncertainty in the lifetime result. Ongoing and possible future uses of the Alpha-Gamma device include 1) Calibration of the neutron fluence monitors that will be used in the upcoming NIST beam neutron lifetime measurement BL2; 2) The first direct, absolute measurement of the 6Li(n,t)4He neutron cross section at sub-thermal neutron energy; 3) Measurements of the 10B(n, γ)11B and 235U(n,f) neutron cross sections; 4) A re-calibration of the national neutron standard NBS-1. The apparatus, measurement technique, and applications will be discussed.

  19. Absolute measurement of neutron fluxes inside the reactor core

    The subject of this work is the development and study of two methods of neutron measurements in nuclear reactors, the new method of high neutron flux measurements and the Li6-semiconductor neutron spectrometer. This work is presented in four sections: Section I. The introduction explains the need for neutron measurements in reactors. A critical survey is given of the existing methods of high neutron flux measurement and methods of fast neutron spectrum determination. Section II. Theoretical basis of the work of semiconductor counters and their most important characteristics are given. Section III. The main point of this section is in presenting the basis of the new method which the author developed, i.e., the long-tube method, and the results obtained by it, with particular emphasis on absolute measurement of high neutron fluxes. Advantages and limitations of this method are discussed in details at the end of this section. Section IV. A comparison of the existing semiconductor neutron spectrometers is made and their advantages and shortcomings underlined. A critical analysis of the obtained results with the Li6-semiconductor spectrometer with plane geometry is given. A new type of Li6-semiconductor spectrometer is described, its characteristics experimentally determined, and a comparison of it with a classical Li6-spectrometer made (author)

  20. Absolute determination of the neutron source yield using melamine as a neutron detector

    Ciechanowski, M.; Bolewski, A., Jr.; Kreft, A.

    2015-01-01

    A new approach to absolute determination of the neutron source yield is presented. It bases on the application of melamine (C3H6N6) to neutron detection combined with Monte Carlo simulations of neutron transport. Melamine has the ability to detect neutrons via 14N(n, p)14C reaction and subsequent determination of 14C content. A cross section for this reaction is relatively high for thermal neutrons (1.827 b) and much lower for fast neutrons. A concentration of 14C nuclei created in the irradiated sample of melamine can be reliably measured with the aid of the accelerator mass spectrometry (AMS). The mass of melamine sufficient for this analysis is only 10 mg. Neutron detection is supported by Monte Carlo simulations of neutron transport carried out with the use of MCNP-4C code. These simulations are aimed at computing the probability of 14C creation in the melamine sample per the source neutron. The result of AMS measurements together with results of MCNP calculations enable us to determine the number of neutrons emitted from the source during the irradiation of melamine. The proposed method was applied for determining the neutron emission from a commercial 252Cf neutron source which was independently calibrated. The measured neutron emission agreed with the certified one within uncertainty limits. The relative expanded uncertainty (k=2) of the absolute neutron source yield determination was estimated at 2.6%. Apart from calibration of radionuclide neutron sources the proposed procedure could facilitate absolute yield measurements for more complex sources. Potential applications of this methodology as it is further developed include diagnostics of inertial confinement fusion and plasma-focus experiments, calibration of neutron measurement systems at tokamaks and accelerator-based neutron sources as well as characterization of neutron fields generated in large particle detectors during collisions of hadron beams.

  1. Automated absolute activation analysis with californium-252 sources

    MacMurdo, K.W.; Bowman, W.W.

    1978-09-01

    A 100-mg /sup 252/Cf neutron activation analysis facility is used routinely at the Savannah River Laboratory for multielement analysis of many solid and liquid samples. An absolute analysis technique converts counting data directly to elemental concentration without the use of classical comparative standards and flux monitors. With the totally automated pneumatic sample transfer system, cyclic irradiation-decay-count regimes can be pre-selected for up to 40 samples, and samples can be analyzed with the facility unattended. An automatic data control system starts and stops a high-resolution gamma-ray spectrometer and/or a delayed-neutron detector; the system also stores data and controls output modes. Gamma ray data are reduced by three main programs in the IBM 360/195 computer: the 4096-channel spectrum and pertinent experimental timing, counting, and sample data are stored on magnetic tape; the spectrum is then reduced to a list of significant photopeak energies, integrated areas, and their associated statistical errors; and the third program assigns gamma ray photopeaks to the appropriate neutron activation product(s) by comparing photopeak energies to tabulated gamma ray energies. Photopeak areas are then converted to elemental concentration by using experimental timing and sample data, calculated elemental neutron capture rates, absolute detector efficiencies, and absolute spectroscopic decay data. Calculational procedures have been developed so that fissile material can be analyzed by cyclic neutron activation and delayed-neutron counting procedures. These calculations are based on a 6 half-life group model of delayed neutron emission; calculations include corrections for delayed neutron interference from /sup 17/O. Detection sensitivities of < or = 400 ppB for natural uranium and 8 ppB (< or = 0.5 (nCi/g)) for /sup 239/Pu were demonstrated with 15-g samples at a throughput of up to 140 per day. Over 40 elements can be detected at the sub-ppM level.

  2. Automated absolute activation analysis with californium-252 sources

    A 100-mg 252Cf neutron activation analysis facility is used routinely at the Savannah River Laboratory for multielement analysis of many solid and liquid samples. An absolute analysis technique converts counting data directly to elemental concentration without the use of classical comparative standards and flux monitors. With the totally automated pneumatic sample transfer system, cyclic irradiation-decay-count regimes can be pre-selected for up to 40 samples, and samples can be analyzed with the facility unattended. An automatic data control system starts and stops a high-resolution gamma-ray spectrometer and/or a delayed-neutron detector; the system also stores data and controls output modes. Gamma ray data are reduced by three main programs in the IBM 360/195 computer: the 4096-channel spectrum and pertinent experimental timing, counting, and sample data are stored on magnetic tape; the spectrum is then reduced to a list of significant photopeak energies, integrated areas, and their associated statistical errors; and the third program assigns gamma ray photopeaks to the appropriate neutron activation product(s) by comparing photopeak energies to tabulated gamma ray energies. Photopeak areas are then converted to elemental concentration by using experimental timing and sample data, calculated elemental neutron capture rates, absolute detector efficiencies, and absolute spectroscopic decay data. Calculational procedures have been developed so that fissile material can be analyzed by cyclic neutron activation and delayed-neutron counting procedures. These calculations are based on a 6 half-life group model of delayed neutron emission; calculations include corrections for delayed neutron interference from 17O. Detection sensitivities of 239Pu were demonstrated with 15-g samples at a throughput of up to 140 per day. Over 40 elements can be detected at the sub-ppM level

  3. Absolute measurement of neutron source emission rate with manganese bath method

    The manganese bath method is one of the most widespread and exact method to measure neutron source emission rate (neutron source intensity) absolutely at present. Pouring some 56Mn solution with known activity into the bath, the system efficiency can be obtained from γ counts of 56Mn, which is measured by two NaI(Tl) detectors. From saturated counts of a 241Am-Be(α, n) neutron source in the bath, the source emission rate can be obtained. An standard 241Am-Be(α, n) source which is the transfer source of the CCRI(Ⅲ)-K9. AmBe international key comparison organized by the Comite Consultatif des Rayonnements Ionisants, was measured absolutely with the neutron source emission rate standard equipment (manganese bath method). The result is coincident with the average value of the comparison within the uncertainties, therefore the reliability of the standard equipment is verified. (authors)

  4. Absolute Energy Calibration with the Neutron-Activated Liquid-Source System at BaBar's CsI(Tl) Calorimeter

    Bauer, Johannes M.; Group, for the BaBar Collaboration EMC

    2003-01-01

    The electro-magnetic calorimeter at the BaBar detector, part of the asymmetric B Factory at SLAC, measures photons in the energy range from 20 MeV to 8 GeV with good resolution. The calorimeter is calibrated at the low energy end with 6.13 MeV photons obtained from a liquid source system. During the calibration, a fluorine-rich liquid is activated via a neutron generator and pumped past the front of the calorimeter's crystals. Decays that occur in front of the crystals emit photons of well-de...

  5. Absolute measurements of the fast neutron capture cross section of 115In

    The 115In(n,#betta#)/sup 116m1/In cross section has been absolutely determined at neutron energies of 23, 265 and 964 keV. These energies are the median neutron energies of the three photo-neutron sources. Sb-Be, Na-CD2 and Na-Be, utilized in this work. The measurements are independent of other cross section data except for corrections amounting to less than 10%. Independent determinations of the reaction rate, detector efficiency, neutron source strength, scalar flux and target masses were performed. Reaction rates were determined by beta counting of the /sup 116ml/In decay activity using a 4π gas flow proportional counter. Detector efficiency was measured using 4π#betta#-#betta# coincidence counting techniques and the foil absorber method of efficiency extrapolation for correction of complex decay scheme effects. Photoneutron source emission rates were determined by intercomparison with the NBS-II calibrated 252Cf spontaneous fission neutron source in the University of Michigan Manganese Bath. The normalized scalar flux was calculated from the neutron emission angular distribution results of the Monte Carlo computer program used to model neutron and gamma transport in the source. Target mass determinations were made with a microbalance. Correction factors were applied for competing reaction activities, neutron scattering from experiment components, room-return induced activities, spectral effects in the manganese bath and the neutron energy spectra of the photoneutron sources. Experimental cross section results were normalized to the source median energy using energy spectra d cross section shape data. The absolute cross sections obtained for the 115In(n,#betta#)/sup 116ml/In reaction were 588 +- 12, 196 +- 4 and 200 +- 3 millibarns at 23, 265 and 964 keV, respectively

  6. Absolute measurements of the fast neutron flux in the reactor RA

    The absolute neutron flux in the vertical VK-5 hole of the reactor RA was determined by using the 27Al (n, alpha) 24Na reaction, and by counting the 24Na - 2.5 MeV gamma line photopeak activity. A method for the determination of σeff as a mean value between the two large limiting cases of neutron spectra is used. The flux at the power level of 5 MW was found to be (2.5±0.9)·1012n/cm2sec (author)

  7. Comparison of two semi-absolute methods. k{sub 0}-instrumental neutron activation analysis and fundamental parameter method X-ray fluorescence spectrometry for Ni-based alloys

    Wasim, Mohammad [Pakistan Institute of Nuclear Science and Technology, Islamabad (Pakistan). Chemistry Div.; Ahmad, Sajjad [Quaid-i-Azam Univ., Islamabad (Pakistan). Dept. of Chemistry

    2015-07-01

    Nickel based alloys play important role in nuclear, mechanical and chemical industry. Two semi-absolute standardless methods, k{sub 0}-instrumental neutron activation analysis (k{sub 0}-INAA) and fundamental parameter X-ray fluorescence spectrometry (FP-XRF) were used for the characterization of certified nickel based alloys. The optimized experimental conditions for NAA provided results for 18 and XRF for 15 elements. Both techniques were unable to quantify some important alloy making elements. However, both reported results of other elements as information values. The techniques were analyzed for their sensitivity and accuracy. Sensitivity was evaluated by the number of elements determined by each technique. Accuracy was ascertained by using the linear regression analysis and the average root mean squared error.

  8. Measuring the absolute deuterium-tritium neutron yield using the magnetic recoil spectrometer at OMEGA and the NIF

    Casey, D. T.; Frenje, J. A.; Gatu Johnson, M.; Seguin, F. H.; Li, C. K.; Petrasso, R. D. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States); Glebov, V. Yu.; Katz, J.; Knauer, J. P.; Meyerhofer, D. D.; Sangster, T. C. [Laboratory for Laser Energetics, UR, Rochester, New York 14623 (United States); Bionta, R. M.; Bleuel, D. L.; Doeppner, T.; Glenzer, S.; Hartouni, E.; Hatchett, S. P.; Le Pape, S.; Ma, T.; MacKinnon, A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2012-10-15

    A magnetic recoil spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.

  9. Measuring the absolute deuterium–tritium neutron yield using the magnetic recoil spectrometer at OMEGA and the NIF

    A magnetic recoil spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.

  10. Measuring the absolute deuterium-tritium neutron yield using the magnetic recoil spectrometer at OMEGA and the NIF.

    Casey, D T; Frenje, J A; Gatu Johnson, M; Séguin, F H; Li, C K; Petrasso, R D; Glebov, V Yu; Katz, J; Knauer, J P; Meyerhofer, D D; Sangster, T C; Bionta, R M; Bleuel, D L; Döppner, T; Glenzer, S; Hartouni, E; Hatchett, S P; Le Pape, S; Ma, T; MacKinnon, A; McKernan, M A; Moran, M; Moses, E; Park, H-S; Ralph, J; Remington, B A; Smalyuk, V; Yeamans, C B; Kline, J; Kyrala, G; Chandler, G A; Leeper, R J; Ruiz, C L; Cooper, G W; Nelson, A J; Fletcher, K; Kilkenny, J; Farrell, M; Jasion, D; Paguio, R

    2012-10-01

    A magnetic recoil spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF. PMID:23126915

  11. Absolute calibration of neutron detectors in the 10- to 30-MeV range

    An experiment was conducted to determine the forward scattering of neutrons from protons at energies below 30 MeV. The associated particle method was used to determine the absolute efficiency of the neutron detector. The reaction chamber for absolute calibration is diagrammed. (U.S.)

  12. Musical Activity Tunes Up Absolute Pitch Ability

    Dohn, Anders; Garza-Villarreal, Eduardo A.; Ribe, Lars Riisgaard; Wallentin, Mikkel; Vuust, Peter

    2014-01-01

    Absolute pitch (AP) is the ability to identify or produce pitches of musical tones without an external reference. Active AP (i.e., pitch production or pitch adjustment) and passive AP (i.e., pitch identification) are considered to not necessarily coincide, although no study has properly compared......, we found that APs generally undershoot when adjusting musical pitch, a tendency that decreases when musical activity increases. Finally, APs are less accurate when adjusting the pitch to black key targets than to white key targets. Hence, AP ability may be partly practice-dependent and we speculate...

  13. Absolute reaction rate measurement with D-D neutron source in polyethylene spherical shell

    The absolute reaction rate distribution measurements in a polyethylene spherical shell with 38.6 cm outside diameter and 10 cm thickness were performed with D-D neutron source. By combining fission method and activation method, rich-uranium fission chamber, depleted-uranium fission chamber, 237Np fission chamber and 115In activation foils were placed at several positions on the equatorial line of the inner face of the shell, and the absolute reaction rates were obtained. The uncertainty of fission rates is 2.5%-4.3%, while the uncertainty of activation rates is about 6.3%. The reaction rates were calculated by MCNP and ENDF/B-VII. 0. The calculated results are lower than the measured results and 238U is typical. (authors)

  14. Absolute measurement of the DT primary neutron yield on the National Ignition Facility

    Leeper R.J.; Bleuel D. L.; Frenje J.A.; Eckart M.J.; Hartouni E.; Kilkenny J.D.; Casey D.T.; Chandler G.A.; Cooper G.W.; Glebov V.Yu.; Hagmann C.; Johnson M. Gatu; Knauer J.P.; Knittel K.M.; Linden-Levy L.A.

    2013-01-01

    The measurement of the absolute neutron yield produced in inertial confinement fusion target experiments conducted on the National Ignition Facility (NIF) is essential in benchmarking progress towards the goal of achieving ignition on this facility. This paper describes three independent diagnostic techniques that have been developed to make accurate and precise DT neutron yield measurements on the NIF.

  15. Absolute measurement of the DT primary neutron yield on the National Ignition Facility

    Leeper R.J.

    2013-11-01

    Full Text Available The measurement of the absolute neutron yield produced in inertial confinement fusion target experiments conducted on the National Ignition Facility (NIF is essential in benchmarking progress towards the goal of achieving ignition on this facility. This paper describes three independent diagnostic techniques that have been developed to make accurate and precise DT neutron yield measurements on the NIF.

  16. Absolute measurement of the DT primary neutron yield on the National Ignition Facility

    The measurement of the absolute neutron yield produced in inertial confinement fusion target experiments conducted on the National Ignition Facility (NIF) is essential in benchmarking progress towards the goal of achieving ignition on this facility. This paper describes three independent diagnostic techniques that have been developed to make accurate and precise DT neutron yield measurements on the NIF. (authors)

  17. Active neutron instrumentation

    An introduction to neutron interactions in tissue and a discussion of pertinent nuetron cross-sections will be given. A brief description of the statistics of energy deposition due to interactions of neutron secondaries in tissue equivalent media is presented. Present and past techniques for measurement of neutron radiation fields are given with advantages and disadvantages in the light of legal limits and proposed changes in those requirements. Neutron dose measuring devices, such as the tissue equivalent proportional counter (TEPC) developed by Rossi, are discussed with emphasis on their response in varying neutron energy spectra. Techniques for determining neutron quality factors from TEPC response functions are discussed along with implications of possible new definitions of quality factor. A brief description of high-resolution spectrometry systems, which use hydrogen, methane and He-3 fill gases, is given with discussion of their limitations. Low resolution systems, such as multisphere spectrometers and activation foils, are also presented

  18. Absolute measurements of neutron cross sections. Progress report

    In the photoneutron laboratory, we have completed a major refurbishing of experimental facilities and begun work on measurements of the capture cross section in thorium and U-238. In the 14 MeV neutron experimental bay, work continues on the measurement of 14 MeV neutron induced reactions of interest as standards or because of their technological importance. First results have been obtained over the past year, and we are extending these measurements along the lines outlined in our proposal of a year ago

  19. Neutron Activation Analysis

    Corliss, William R.

    1968-01-01

    In activation analysis, a sample of an unknown material is first irradiated (activated) with nuclear particles. In practice these nuclear particles are almost always neutrons. The success of activation analysis depends upon nuclear reactions which are completely independent of an atom's chemical associations. The value of activation analysis as a research tool was recognized almost immediately upon the discovery of artificial radioactivity. This book discusses activation analysis experiments, applications and technical considerations.

  20. Absolute measurement of $sup 235$U fission cross-section for 2200 m/sec neutrons

    Borcea, C.; Borza, A.; Buta, A.

    1973-12-31

    The results of an absolute fission cross-section measurement of /sup 235/ U are presented; the thermal neutrons were selected by the time-of-flight method. The principle of the method and the experimental apparatus are described. The method had the advantage of avoiding the use of an intermediate cross section in the neutron flux determination by choice of a B target thick enough to absorb all thermal neutrons. Target preparation, efficiency determination, corrections, etc., are reported. The value determined was 581.7 plus or minus 7.8 barns. (6 figures, 4 tables) (RWR)

  1. Isotopic neutron sources for neutron activation analysis

    This User's Manual is an attempt to provide for teaching and training purposes, a series of well thought out demonstrative experiments in neutron activation analysis based on the utilization of an isotopic neutron source. In some cases, these ideas can be applied to solve practical analytical problems. 19 refs, figs and tabs

  2. SLOWPOKE: neutron activation analysis

    Neutron activation analysis permits the non-destructive determination of trace elements in crude oil and its derivatives at high sensitivity (up to 10-9 g/g) and good precision. This article consists of a quick survey of the method followed by an illustration based on the results of recent work at the SLOWPOKE reactor laboratory at the Ecole Polytechnique

  3. Neutron production, shielding and activation

    This chapter contains information on neutron cross-sections, production, spectra and yields; detection and detectors; shielding with various materials, particularly with ordinary concrete; and neutron activation products of interest to health physicists. Neutron energy terminology as well as neutron energy spectrum calculations are included

  4. Educational activities for neutron sciences

    Since now we have several world-leading neutron science facilities in Japan, enlightenment activities for introducing neutron sciences, for example, to young people is an indispensable issue. Hereafter, we will report present status of the activities based on collaborations between universities and neutron facilities. A few suggestions for future educational activity of JSNS are also shown. (author)

  5. Absolute measurement of the 242Pu neutron-capture cross section

    Buckner, M. Q.; Wu, C. Y.; Henderson, R. A.; Bucher, B.; Chyzh, A.; Bredeweg, T. A.; Baramsai, B.; Couture, A.; Jandel, M.; Mosby, S.; O'Donnell, J. M.; Ullmann, J. L.; Dance Collaboration

    2016-04-01

    The absolute neutron-capture cross section of 242Pu was measured at the Los Alamos Neutron Science Center using the Detector for Advanced Neutron-Capture Experiments array along with a compact parallel-plate avalanche counter for fission-fragment detection. The first direct measurement of the 242Pu(n ,γ ) cross section was made over the incident neutron energy range from thermal to ≈6 keV, and the absolute scale of the (n ,γ ) cross section was set according to the known 239Pu(n ,f ) resonance at En ,R=7.83 eV. This was accomplished by adding a small quantity of 239Pu to the 242Pu sample. The relative scale of the cross section, with a range of four orders of magnitude, was determined for incident neutron energies from thermal to ≈40 keV. Our data, in general, are in agreement with previous measurements and those reported in ENDF/B-VII.1; the 242Pu(n ,γ ) cross section at the En ,R=2.68 eV resonance is within 2.4 % of the evaluated value. However, discrepancies exist at higher energies; our data are ≈30 % lower than the evaluated data at En≈1 keV and are approximately 2 σ away from the previous measurement at En≈20 keV.

  6. Absolute measurement of the subcriticality based on the third order neutron correlation in consideration of the finite nature of neutron counts data

    We have studied a measurement of subcriticality by using the neutron correlation method. Furuhashi proposed an absolute measurement of subcriticality by using the third order neutron correlation factor X in addition to the second order neutron correlation factor Y. In actual experiments, the number of neutron counts data is not infinity so that we take the effect of the finite nature of the neutron counts data into account. We derived new formulas in consideration of the number of data and verified them. (author)

  7. Absolute calibration of small angle neutron scattering data using strong coherent scattering

    Lee, D.; Barker, J; Chen, S.

    1993-01-01

    Typically, small angle neutron scattering (SANS) data is normalized to an absolute scale using secondary standards such as water, polymers, silica gels, or irradiated aluminum. Errors for this method of calibration arise when the initial determination or calculation of the standard's scattering cross-section is no longer valid due to degradation or wavelength-dependent multiple scattering or detector efficiency effects. Here we illustrate how strong coherent scattering can be used to experime...

  8. Absolute calibration of TFTR neutron detectors for D-T plasma operation

    The two most sensitive TFTR fission-chamber detectors were absolutely calibrated in situ by a D-T neutron generator (∼5 x 107 n/s) rotated once around the torus in each direction, with data taken at about 45 positions. The combined uncertainty for determining fusion neutron rates, including the uncertainty in the total neutron generator output (±9%), counting statistics, the effect of coil coolant, detector stability, cross-calibration to the current mode or log Campbell mode and to other fission chambers, and plasma position variation, is about ±13%. The NE-451 (ZnS) scintillators and 4He proportional counters that view the plasma in up to 10 collimated sightlines were calibrated by scanning. the neutron generator radially and toroidally in the horizontal midplane across the flight tubes of 7 cm diameter. Spatial integration of the detector responses using the calibrated signal per unit chord-integrated neutron emission gives the global neutron source strength with an overall uncertainty of ±14% for the scintillators and ±15% for the 4He counters

  9. PC based system for absolute neutron flux-spectrum measurements. Final report for the period 1 April 1994 - 15 December 1997

    When measuring absolute neutron flux-spectra, thin detector foils are irradiated in a neutron field. The absolute activity of isotopes generated by activation or fission reactions (fission products) is then measured, using an efficiency calibrated high resolution gamma-ray spectroscopy system, and the absolute reaction rates for their production is determined. Finally the flux-spectrum is determined based upon the reaction rate values. A general method to obtain flux-spectra from the reaction rate is the unfolding method. The above process involves computations of photopeak area, reaction rate, flux perturbation corrections and flux-spectrum. The PC's are well suited for the data processing system outlined above. Using available interfaces, the PC's can be involved even in the data acquisition. Graphical facilities allow decision upon the data processing flow

  10. First measurements of the absolute neutron spectrum using the magnetic recoil spectrometer at OMEGA (invited)

    A neutron spectrometer, called a magnetic recoil spectrometer (MRS), has been built and implemented at the OMEGA laser facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] for absolute measurements of the neutron spectrum in the range of 6-30 MeV, from which fuel areal density (ρR), ion temperature (Ti), and yield (Yn) can be determined. The results from the first MRS measurements of the absolute neutron spectrum are presented. In addition, measuring ρR at the National Ignition Facility (NIF) [G. H. Miller et al., Nucl. Fusion 44, S228 (2004)] will be essential for assessing implosion performance during all stages of development from surrogate implosions to cryogenic fizzles to ignited implosions. To accomplish this, we are also developing an MRS for the NIF. As much of the research and development and instrument optimization of the MRS at OMEGA are directly applicable to the MRS at the NIF, a description of the design and characterization of the MRS on the NIF is discussed as well.

  11. First measurements of the absolute neutron spectrum using the Magnetic Recoil Spectrometer (MRS) at OMEGA

    A new type of neutron spectrometer, called a Magnetic Recoil Spectrometer (MRS), has been built and implemented at the OMEGA laser facility (T. R. Boehly. D. L. Brown, R. S. Craxton et al., Opt. Commun. 133, 495 (1997)) for absolute measurements of the neutron spectrum in the range 6 to 30 MeV, from which fuel areal density (ρR), ion temperature (Ti) and yield (Yn) can be determined. The results from the first MRS measurements of the absolute neutron spectrum are presented. In addition, measuring ρR at the National Ignition Facility (NIF) (G.H. Miller, E.I. Moses and C.R. Wuest, Nucl. Fusion 44, S228 (2004)) will be essential for assessing implosion performance during all stages of development from surrogate implosions to cryogenic fizzles and ignited implosions. To accomplish this, we are also developing an MRS for the NIF. As much of the R and D and instrument optimization of the MRS at OMEGA is directly applicable to the MRS at the NIF, a description of the MRS design on the NIF is discussed as well

  12. First measurements of the absolute neutron spectrum using the Magnetic Recoil Spectrometer (MRS) at OMEGA

    Frenje, J A; Casey, D T; Li, C K; Rygg, J R; Seguin, F H; Petrasso, R D; Glebov, V Y; Meyerhofer, D D; Sangster, T C; Hatchett, S; Haan, S; Cerjan, C; Landen, O; Moran, M; Song, P; Wilson, D C; Leeper, R J

    2008-05-12

    A new type of neutron spectrometer, called a Magnetic Recoil Spectrometer (MRS), has been built and implemented at the OMEGA laser facility [T. R. Boehly. D. L. Brown, R. S. Craxton et al., Opt. Commun. 133, 495 (1997)] for absolute measurements of the neutron spectrum in the range 6 to 30 MeV, from which fuel areal density ({rho}R), ion temperature (T{sub i}) and yield (Y{sub n}) can be determined. The results from the first MRS measurements of the absolute neutron spectrum are presented. In addition, measuring {rho}R at the National Ignition Facility (NIF) [G.H. Miller, E.I. Moses and C.R. Wuest, Nucl. Fusion 44, S228 (2004)] will be essential for assessing implosion performance during all stages of development from surrogate implosions to cryogenic fizzles and ignited implosions. To accomplish this, we are also developing an MRS for the NIF. As much of the R&D and instrument optimization of the MRS at OMEGA is directly applicable to the MRS at the NIF, a description of the MRS design on the NIF is discussed as well.

  13. First measurements of the absolute neutron spectrum using the magnetic recoil spectrometer at OMEGA (invited).

    Frenje, J A; Casey, D T; Li, C K; Rygg, J R; Séguin, F H; Petrasso, R D; Glebov, V Yu; Meyerhofer, D D; Sangster, T C; Hatchett, S; Haan, S; Cerjan, C; Landen, O; Moran, M; Song, P; Wilson, D C; Leeper, R J

    2008-10-01

    A neutron spectrometer, called a magnetic recoil spectrometer (MRS), has been built and implemented at the OMEGA laser facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] for absolute measurements of the neutron spectrum in the range of 6-30 MeV, from which fuel areal density (rhoR), ion temperature (T(i)), and yield (Y(n)) can be determined. The results from the first MRS measurements of the absolute neutron spectrum are presented. In addition, measuring rhoR at the National Ignition Facility (NIF) [G. H. Miller et al., Nucl. Fusion 44, S228 (2004)] will be essential for assessing implosion performance during all stages of development from surrogate implosions to cryogenic fizzles to ignited implosions. To accomplish this, we are also developing an MRS for the NIF. As much of the research and development and instrument optimization of the MRS at OMEGA are directly applicable to the MRS at the NIF, a description of the design and characterization of the MRS on the NIF is discussed as well. PMID:19044488

  14. High-capacity neutron activation analysis facility

    A high-capacity neutron activation analysis facility, the Reactor Activation Facility, was designed and built and has been in operation for about a year at one of the Savannah River Plant's production reactors. The facility determines uranium and about 19 other elements in hydrogeochemical samples collected in the National Uranium Resource Evaluation program, which is sponsored and funded by the United States Department of Energy, Grand Junction Office. The facility has a demonstrated average analysis rate of over 10,000 samples per month, and a peak rate of over 16,000 samples per month. Uranium is determined by cyclic activation and delayed neutron counting of the U-235 fission products; other elements are determined from gamma-ray spectra recorded in subsequent irradiation, decay, and counting steps. The method relies on the absolute activation technique and is highly automated for round-the-clock unattended operation

  15. Measurement of the absolute values of cross-sections in neutron photoproduction (1962)

    The absolute values of photoneutrons production cross-sections for the case of intermediate and heavy nuclei (lanthanium, cerium, tantalum, gold, lead and bismuth) are determined with an error of 15 per cent. The results obtained agree with theories in which the giant resonance is explained by the collective motion of the protons against the neutrons. The effect of the nuclear deformation on the shape of the giant resonance is seen in the case of Ta181, it will be possible to determine the quadrupole momenta of deformed nuclei with a good accuracy when we shall increase the statistics of measurements. (author)

  16. The magnetic recoil spectrometer for measurements of the absolute neutron spectrum at OMEGA and the NIF.

    Casey, D T; Frenje, J A; Johnson, M Gatu; Séguin, F H; Li, C K; Petrasso, R D; Glebov, V Yu; Katz, J; Magoon, J; Meyerhofer, D D; Sangster, T C; Shoup, M; Ulreich, J; Ashabranner, R C; Bionta, R M; Carpenter, A C; Felker, B; Khater, H Y; LePape, S; MacKinnon, A; McKernan, M A; Moran, M; Rygg, J R; Yeoman, M F; Zacharias, R; Leeper, R J; Fletcher, K; Farrell, M; Jasion, D; Kilkenny, J; Paguio, R

    2013-04-01

    The neutron spectrum produced by deuterium-tritium (DT) inertial confinement fusion implosions contains a wealth of information about implosion performance including the DT yield, ion-temperature, and areal-density. The Magnetic Recoil Spectrometer (MRS) has been used at both the OMEGA laser facility and the National Ignition Facility (NIF) to measure the absolute neutron spectrum from 3 to 30 MeV at OMEGA and 3 to 36 MeV at the NIF. These measurements have been used to diagnose the performance of cryogenic target implosions to unprecedented accuracy. Interpretation of MRS data requires a detailed understanding of the MRS response and background. This paper describes ab initio characterization of the system involving Monte Carlo simulations of the MRS response in addition to the commission experiments for in situ calibration of the systems on OMEGA and the NIF. PMID:23635195

  17. The magnetic recoil spectrometer for measurements of the absolute neutron spectrum at OMEGA and the NIF

    The neutron spectrum produced by deuterium-tritium (DT) inertial confinement fusion implosions contains a wealth of information about implosion performance including the DT yield, ion-temperature, and areal-density. The Magnetic Recoil Spectrometer (MRS) has been used at both the OMEGA laser facility and the National Ignition Facility (NIF) to measure the absolute neutron spectrum from 3 to 30 MeV at OMEGA and 3 to 36 MeV at the NIF. These measurements have been used to diagnose the performance of cryogenic target implosions to unprecedented accuracy. Interpretation of MRS data requires a detailed understanding of the MRS response and background. This paper describes ab initio characterization of the system involving Monte Carlo simulations of the MRS response in addition to the commission experiments for in situ calibration of the systems on OMEGA and the NIF.

  18. The magnetic recoil spectrometer for measurements of the absolute neutron spectrum at OMEGA and the NIF

    Casey, D. T.; Frenje, J. A.; Gatu Johnson, M.; Seguin, F. H.; Li, C. K.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Glebov, V. Yu.; Katz, J.; Magoon, J.; Meyerhofer, D. D.; Sangster, T. C.; Shoup, M.; Ulreich, J. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Ashabranner, R. C.; Bionta, R. M.; Carpenter, A. C.; Felker, B.; Khater, H. Y.; LePape, S.; MacKinnon, A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2013-04-15

    The neutron spectrum produced by deuterium-tritium (DT) inertial confinement fusion implosions contains a wealth of information about implosion performance including the DT yield, ion-temperature, and areal-density. The Magnetic Recoil Spectrometer (MRS) has been used at both the OMEGA laser facility and the National Ignition Facility (NIF) to measure the absolute neutron spectrum from 3 to 30 MeV at OMEGA and 3 to 36 MeV at the NIF. These measurements have been used to diagnose the performance of cryogenic target implosions to unprecedented accuracy. Interpretation of MRS data requires a detailed understanding of the MRS response and background. This paper describes ab initio characterization of the system involving Monte Carlo simulations of the MRS response in addition to the commission experiments for in situ calibration of the systems on OMEGA and the NIF.

  19. Reference neutron activation library

    Many scientific endeavors require accurate nuclear data. Examples include studies of environmental protection connected with the running of a nuclear installation, the conceptual designs of fusion energy producing devices, astrophysics and the production of medical isotopes. In response to this need, many national and international data libraries have evolved over the years. Initially nuclear data work concentrated on materials relevant to the commercial power industry which is based on the fission of actinides, but recently the topic of activation has become of increasing importance. Activation of materials occurs in fission devices, but is generally overshadowed by the primary fission process. In fusion devices, high energy (14 MeV) neutrons produced in the D-T fusion reaction cause activation of the structure, and (with the exception of the tritium fuel) is the dominant source of activity. Astrophysics requires cross-sections (generally describing neutron capture) or its studies of nucleosynthesis. Many analytical techniques require activation analysis. For example, borehole logging uses the detection of gamma rays from irradiated materials to determine the various components of rocks. To provide data for these applications, various specialized data libraries have been produced. The most comprehensive of these have been developed for fusion studies, since it has been appreciated that impurities are of the greatest importance in determining the overall activity, and thus data on all elements are required. These libraries contain information on a wide range of reactions: (n,γ), (n,2n), (n,α), (n,p), (n,d), (n,t), (n,3He)and (n,n')over the energy range from 10-5 eV to 15 or 20 MeV. It should be noted that the production of various isomeric states have to be treated in detail in these libraries,and that the range of targets must include long-lived radioactive nuclides in addition to stable nuclides. These comprehensive libraries thus contain almost all the

  20. Applications of neutron activation spectroscopy

    Silarski, M

    2013-01-01

    Since the discovery in 1932, neutrons became a basis of many methods used not only in research, but also in industry and engineering. Among others, the exceptional role in the modern nuclear engineering is played by the neutron activation spectroscopy, based on the interaction of neutron flux with atomic nuclei. In this article we shortly describe application of this method in medicine and detection of hazardous substances.

  1. Absolute calibration of neutron detectors in the 10--30 MeV energy range

    A central problem in fast neutron research is that of finding the absolute efficiency of neutron detectors. Using the associated particle method for this purpose, we have designed a chamber to count He particles from the D(d,n)3He or the T(d,n)4He reaction in coincidence with neutron events. The reactions take place in deuterium or tritium gas and a ΔE solid state counter at 800, 650, or 430 to the 2-10 MeV deuteron beam direction detects the He particles with 100 percent efficiency. To reduce background we allow the deuterons to pass out of the gas chamber through a Ni window and stop the beam approximately 150 cm from the counters. With the D(d,n)3He reaction we have obtained approximately 2 percent efficiency calibration of the central portion of a liquid scintillator in the 9-10 MeV energy range. With the T(d,n) reaction this calibration can be extended to approximately 27 MeV and the efficiency can be mapped out as a function of position in the scintillator

  2. Absolute configuration and antimicrobial activity of acylhomoserine lactones.

    Pomini, Armando M; Marsaioli, Anita J

    2008-06-01

    (S)-N-Heptanoylhomoserine lactone is an uncommon acyl odd-chain natural product employed by many Gram-negative bacteria as a signaling substance in chemical communication mechanisms known as quorum sensing. The absolute configuration determination of the metabolite produced by the phytopathogen Pantoea ananatis Serrano is reported herein. As with all other substances of this class, the lactone moiety possesses S configuration, corroborating the hypothesis that it shares the same biosynthetic pathway as the (S)-N-hexanoylhomoserine lactone and also that some LuxI homologues can accept both hexanoyl- and heptanoyl-ACP as precursors. Evaluation of the antimicrobial activity of enantiomeric acylhomoserine lactones against three Gram-positive bacteria (Bacillus cereus, B. subtilis, and Staphylococcus aureus) revealed important features between absolute configuration and antimicrobial activity. The N-heptanoylhomoserine lactone was considerably less active than the 3-oxo derivatives. Surprisingly, non-natural (R)-N-(3-oxo-octanoyl)homoserine lactone was as active as the S enantiomer against B. cereus, while the synthetic racemic product was less active than either enantiomer. PMID:18465897

  3. Neutron activation analysis of coins

    Activation analysis was applied to the study of coins using 14MeV neutrons produced by an accelerator for the determination of oxygen and neutrons emitted from a 252Cf source for the determination of the other elements (Au, Ag, Cu, As etc...). The advantages of this technique are presented

  4. Absolute fission rate measurement of 238U induced by 14 MeV neutrons penetrated composite material

    In order to prove the model calculation method and parameter, the 238U absolute fission rate in the case of 14 MeV neutrons penetrating through the special composite material was measured by minitype slab uranium fission chambers. The measuring spots are distributed in the surface of iron ball hull along the different position of equator. The calculated results are compared with the experiment results. The total error of measured 238U absolute fission rate is 6.1%. (author)

  5. The absolute determination of activity by the efficiency extrapolation method

    As agent for the Commonwealth Scientific and Industrial Research Organisation, the Australian Atomic Energy Commission is responsible for the maintenance of the Australian standard of activity. The standard comprises activity measurement procedures involving the operation of 4 π β-γ coincidence counting equipment. The coincidence method requires the application of correction factors which depend on detection efficiency, such as arise for complex decay schemes and internal conversion. These corrections approach unity as the detection efficiency in the β-channel approaches 100 per cent. By performing activity determinations for a range of β detection efficiencies, an 'efficiency extrapolation' analysis can be applied which eliminates the need to determine the absolute detection efficiency for each channel

  6. On the absolute calibration of a DT fusion neutron yield diagnostic

    Ruiz C.L.

    2013-11-01

    Full Text Available Recent advances in Inertial Confinement Fusion (ICF experiments at Lawrence Livermore National Laboratory's National Ignition Facility (NIF have underscored the need for accurate total yield measurements of DT neutrons because yield measurements provide a measure of the predicted performance of the experiments. Future gas-puff DT experiments at Sandia National Laboratory's Z facility will also require similar measurements. For ICF DT experiments, the standard technique for measuring the neutron (14.1 MeV yield, counts the activity (counts/minute induced in irradiated copper samples. This activity occurs by the 63Cu(n,2n62Cu reaction where 62Cu decays by positrons (β+ with a half-life of 9.67 minutes. The calibrations discussed here employ the associated-particle method (APM, where the α (4He particles from the T(d,n4He reaction are measured to infer neutron fluxes on a copper sample. The flux induces 62Cu activity, measured in a coincidence counting system. The method leads to a relationship between a DT neutron yield and copper activity known as the F-factor. The goal in future experiments is to apply this calibration to measure the yield at NIF with a combined uncertainty approaching 5%.

  7. Flux depression and the absolute measurement of the thermal neutron flux density

    The thermal neutron flux depression in a diffusing medium by an absorbing foil has been treated in numerous papers. The results are re-examined in an attempt to find a uniform and physically meaningful representation of the 'activation correction'. This quantity can be split up into a combination of probabilities. Thus, it is possible to determine the activation correction for any moderator and foil material. Measurements confirm the utility of the concepts introduced

  8. Flux depression and the absolute measurement of the thermal neutron flux density

    The thermal neutron flux depression in a diffusing medium by an absorbing foil has been treated in numerous papers. The results are re-examined in an attempt to find a uniform and physically meaningful representation of the 'activation correction'. This quantity can be split up into a combination of probabilities. Thus, it is possible to determine the activation correction for any moderator and foil material. Measurements confirm the utility of the concepts introduced. (orig.)

  9. Application of neutron activation analysis

    The physical basis and analytical possibilities of neutron activation analysis have been performed. The number of applications in material engineering, geology, cosmology, oncology, criminology, biology, agriculture, environment protection, archaeology, history of art and especially in chemical analysis have been presented. The place of the method among other methods of inorganic quantitative chemical analysis for trace elements determination has been discussed

  10. Development of highly efficient proton recoil counter telescope for absolute measurement of neutron fluences in quasi-monoenergetic neutron calibration fields of high energy

    Precise calibration of monitors and dosimeters for use with high energy neutrons necessitates reliable and accurate neutron fluences being evaluated with use of a reference point. A highly efficient Proton Recoil counter Telescope (PRT) to make absolute measurements with use of a reference point was developed to evaluate neutron fluences in quasi-monoenergetic neutron fields. The relatively large design of the PRT componentry and relatively thick, approximately 2 mm, polyethylene converter contributed to high detection efficiency at the reference point over a large irradiation area at a long distance from the target. The polyethylene converter thickness was adjusted to maintain the same carbon density per unit area as the graphite converter for easy background subtraction. The high detection efficiency and thickness adjustment resulted in efficient absolute measurements being made of the neutron fluences of sufficient statistical precision over a short period of time. The neutron detection efficiencies of the PRT were evaluated using MCNPX code at 2.61x10-6, 2.16x10-6 and 1.14x10-6 for the respective neutron peak energies of 45, 60 and 75 MeV. The neutron fluences were determined to have been evaluated at an uncertainty of within 6.5% using analysis of measured data and the detection efficiencies. The PRT was also designed so as to be capable of simultaneously obtaining TOF data. The TOF data also increased the reliability of neutron fluence measurements and provided useful information for use in interpreting the source of proton events.

  11. Neutron activation analysis in Bulgaria

    The development of instrumental neutron activation analysis (INAA) as a routine method started in 1960 with bringing into use of the experimental nuclear reactor 2 MW -IRT-2000. For the purposes of INAA the vertical channels were used. The neutron flux vary from 1 to 6x1012n/cm2s, with Cd ratio for gold of about 4,4. In one of the channels the neutron flux is additionally thermalised with grafite, in others - a pneumatic double-tube rabbit system is installed. One of the irradiation positions is equiped with 1 mm Cd shield constantly. With the pressure of the working gas (air) of 2 bar the transport time in one direction is 2,5 sec. Because of lack of special system for uniform irradiation an accuracy of 3% can be reached by use of iron monitors for long irradiations and copper monitors for use in the rabbit system. Two neutron generators are also working but the application of 14 MeV neutrons for INAA is still quite limited. The most developed are the applications of INAA in the fields of geology and paedology, medicine and biology, environment and pollution, archaeology, metallurgy, metrology and hydrology, criminology

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

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

    2015-07-01

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

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

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

  14. Activation analysis with reactor neutrons

    The potentialities of neutron as an analytical probe are indicated, pointing out the need for development of other approaches, besides the conventional activation method. Development of instrumental approach to activation and applications, carried out at Analytical Chemistry Division are outlined. The role of, and the need for, the development and application of mathematical methods in enhancing the information content, and in turn the interpretation of the analytical results, is demonstrated. (author)

  15. Neutron activation spectrometry and neutron activation analysis in analytical geochemistry

    The present report is to show the geochemists who are interested in neutron activation spectrometry (NAS) and neutron activation analysis (NAA) which analytical possibilities these methods offer him. As a review of these analytical possibilities, a lieterature compolation is given which is subdivided into two groups: 1) rock (basic, intermediary, acid, sediments, soils and nuds, diverse minerals, tectites, meteorites and lunar material). 2) ore (Al, Au, Be, Cr, Cu, Mn, Mo, Fe, Pb, Pt, Sn, Ti, W, Zn, Zr, U and phosphate ore, polymetallic ores, fluorite, monazite and diverse ores). The applied methods as well as the determinable elements in the given materials can be got from the tables. On the whole, the literature evaluation carried out makes it clear that neutron activation spectrometry is a very useful multi-element method for the analysis of rocks. The analysis of ores, however, is subjected to great limitations. As rock analysis is very frequently of importance in prospecting for ore deposits, the NAS proves to be extremely useful for this very field of application. (orig./LH)

  16. A method for in situ absolute DD yield calibration of neutron time-of-flight detectors on OMEGA using CR-39-based proton detectors

    Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule

  17. A method for in situ absolute DD yield calibration of neutron time-of-flight detectors on OMEGA using CR-39-based proton detectors.

    Waugh, C J; Rosenberg, M J; Zylstra, A B; Frenje, J A; Séguin, F H; Petrasso, R D; Glebov, V Yu; Sangster, T C; Stoeckl, C

    2015-05-01

    Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule. PMID:26026524

  18. A method for in situ absolute DD yield calibration of neutron time-of-flight detectors on OMEGA using CR-39-based proton detectors

    Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule

  19. A method for in situ absolute DD yield calibration of neutron time-of-flight detectors on OMEGA using CR-39-based proton detectors

    Waugh, C. J., E-mail: cjwaugh@mit.edu; Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; Petrasso, R. D. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States); Rosenberg, M. J.; Glebov, V. Yu.; Sangster, T. C.; Stoeckl, C. [Laboratory for Laser Energetics, Rochester, New York 14623 (United States)

    2015-05-15

    Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule.

  20. Neutron activation analysis of cheese, eggs, fish, fowl and meats

    The concentrations of Br, Ca, Cl, Cu, I, K, Mg, Na, Rb, S and Ti in 44 samples of cheese, eggs, fish, fowl and meats sold in Canada were determined with absolute instrumental neutron activation analysis. The procedure is fully computerized and incorporates one short irradiation and counting only. When an element was not detected, its detection limit was calculated. The nuclear interferences and blanks were taken into account. The nutritional significance of the results is discussed. (author)

  1. In vivo neutron activation facility at Brookhaven National Laboratory

    Ma, R.; Yasumura, Seiichi; Dilmanian, F.A.

    1997-11-01

    Seven important body elements, C, N, Ca, P, K, Na, and Cl, can be measured with great precision and accuracy in the in vivo neutron activation facilities at Brookhaven National Laboratory. The facilities include the delayed-gamma neutron activation, the prompt-gamma neutron activation, and the inelastic neutron scattering systems. In conjunction with measurements of total body water by the tritiated-water dilution method several body compartments can be defined from the contents of these elements, also with high precision. In particular, body fat mass is derived from total body carbon together with total body calcium and nitrogen; body protein mass is derived from total body nitrogen; extracellular fluid volume is derived from total body sodium and chlorine; lean body mass and body cell mass are derived from total body potassium; and, skeletal mass is derived from total body calcium. Thus, we suggest that neutron activation analysis may be valuable for calibrating some of the instruments routinely used in clinical studies of body composition. The instruments that would benefit from absolute calibration against neutron activation analysis are bioelectric impedance analysis, infrared interactance, transmission ultrasound, and dual energy x-ray/photon absorptiometry.

  2. Systematic determination of the JET absolute neutron yield using the MPR spectrometer

    This thesis describes the first high-statistics systematic analysis of JET neutron yield and rate measurements obtained by using data acquired with the Magnetic Proton Recoil (MPR) neutron spectrometer. The neutron yield and rate were determined by using the count-rate from the MPR neutron spectrometer together with neutron profile information from other neutron diagnostic systems. This has previously been done manually for a few pulses. To be able to do this in a more systematic way a part of the neutron spectrum evaluation code was extracted and put into a separate custom-made program and modifications were done to extract sets of MPR data automatically. The codes have been used for analysis of a large set of pulses from the deuterium-tritium campaign at JET in 1997. Several results were obtained, the most significant of which was the clear improvement seen when neutron profile corrections were applied. Neutron yield-rates derived from MPR count-rate are shown to be in excellent agreement with other JET neutron diagnostic data

  3. Systematic determination of the JET absolute neutron yield using the MPR spectrometer

    Kronborg-Pettersson, N

    2003-04-01

    This thesis describes the first high-statistics systematic analysis of JET neutron yield and rate measurements obtained by using data acquired with the Magnetic Proton Recoil (MPR) neutron spectrometer. The neutron yield and rate were determined by using the count-rate from the MPR neutron spectrometer together with neutron profile information from other neutron diagnostic systems. This has previously been done manually for a few pulses. To be able to do this in a more systematic way a part of the neutron spectrum evaluation code was extracted and put into a separate custom-made program and modifications were done to extract sets of MPR data automatically. The codes have been used for analysis of a large set of pulses from the deuterium-tritium campaign at JET in 1997. Several results were obtained, the most significant of which was the clear improvement seen when neutron profile corrections were applied. Neutron yield-rates derived from MPR count-rate are shown to be in excellent agreement with other JET neutron diagnostic data.

  4. Development and application of a detector for absolute measurement of neutron fluence rate in MeV region

    The development and performance of the DTS (Dual Thin Scintillator) for the absolute measurement of the neutron fluence rate between 1 and 15 MeV is decribed. The DTS detector consists of a pair of organic scintillators in a dual configuration, where the incident produces a proton-recoil which is detected in a 2Π geometry therefore avoiding the effect of the escape of protons. Thin scintillators are used resulting in small multiple scattering corrections. The theoretical caluclations of detector efficiency and proton-recoil spectrum were performed by means of a Monte Carlos code - CARLO DTS. The calculated efficiency was compared to the experimental one at two neutron energies namely 2.446 MeV and 14.04 MeV applying the Time Correlated Associated Particle technique. The theoretical and experimental efficiencies agreed within the experimental uncertainties of 1.44% and 0.77%, respectively. The performance of the DTS has been verified in an absolute 235U(n,f) cross section measurement between 1 and 6 MeV neutron energy. The cross section results were compared to those obtained replacing the DTS detector by the NBS (National Bureau of Standards, USA) Black Neutron Detector. The agreement was excellent in the overlapping energy interval of the two experiments (between 1 and 3 MeV), within the estimated uncertainly in the range of 1,0 to 1,7%. The agreement with the most recent evaluation from the ENDF/B-VI was excellent in almost all the energy range between 1 and 6 MeV. The 235U(n,f) cross section, average over the 252Cf fission neutron spectrum has been evaluated. The result including the cross section values of the present work was 1220 mb, in excellent agreement with the average value among the most recent measurements, 1227 +- 12 mb, and with the value 1213 mb, using the ENDF/B-VI data. (author)

  5. Neutron activations at the neutron facility of TU-Dresden

    Domula, Alexander; Zuber, Kai [TU Dresden, Institut fuer Kern- und Teilchenphysik, 01069 Dresden (Germany); Gehre, Daniel [TU Dresden, Institut fuer Kern- und Teilchenphysik, 01069 Dresden (Germany); FZD, Institut fuer Strahlenphysik, 01314 Dresden (Germany); Klix, Axel [KIT, Institut fuer Neutronenphysik und Reaktortechnik, 76344 Eggenstein-Leopoldshafen (Germany)

    2010-07-01

    The Technical University of Dresden (TUD) operates at the Forschungszentrum Dresden-Rossendorf (FZD) a 14 MeV Neutron Generator (NG) with fast, mono energetic neutrons from the T(d,{alpha})n reaction and 2.5 MeV neutrons from the D(d,x)n reaction. Since its commissioning in 2004 the NG is involved in the validation of European Activation File and mockup experiments for validation of neutron transport data in collaborations with FZK/KIT, PTB, ENEA, JAEA, Osaka University and University Vienna. Cross section measurements have been limited to long living isotopes. An automated sample changer is currently set up in order to extend the capabilities to radioisotopes with half-lives in the range from seconds to a few minutes. The general layout of the neutron facility is described. First example activations for GERDA and SNO+ have been made and are presented here.

  6. The Atomic Fingerprint: Neutron Activation Analysis

    Keisch, Bernard [Carnegie-Mellon University

    1972-01-01

    The nuclei of atoms are stable only when they contain certain numbers of neutrons and protons. Since nuclei can absorb additional neutrons, which in many cases results in the conversion of a stable nucleus to a radioactive one, neutron activation analysis is possible.

  7. Instrumentation in neutron activation analysis

    The rise of neutron activation analysis (NAA) as a tool in geochemical research has parallelled advances in detector, multi-channel analyzer, and computer technology. Micro-computers are now being integrated into NAA systems, and gamma-ray spectrometer instrumentation is evolving towards direct-reading systems. The investigator is faced with a wide range of possibilities and choices when equipping or re-equipping a laboratory. The geoscientist is provided with an overview of the available instrumentation and what soon may be feasible. (L.L.)

  8. Measurements of periods, relative abundances and absolute yields of delayed neutrons from fast neutron induced fission of {sup 237}Np

    Piksaikine, V. [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

    1997-03-01

    The experimental method for measurements of the delayed neutron yields and period is presented. The preliminary results of the total yield, relative abundances and periods are shown comparing with the previously reported values. (J.P.N.)

  9. Recent activities on neutron beam utilization

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

  10. Fast-neutron spectrum and absolute fast flux measurements in TR-1 reactor core and its reflector

    In this work, we tried to determine experimentally the parameter of an analytical expression for the fast neutron spectrum. We thus aimed to determine the fast neutron spectra in various location of the TR-1 (Cekmece Nuclear Research and Training Reactor). Threshold detectors In115, Ni58, AL27 were irradiated in different locations in the core and graphits regions of TR-1. Through the related activity measurements the parameters in question were found, thus the spectra could be calculated. The spectra is further used to compute the various spectrum avaraged neutron cross section in fast energy region

  11. Neutron fluence spectrometry using disk activation

    A simple and robust detector for spectrometry of environmental neutrons has been developed. The technique is based on neutron activation of a series of different metal disks followed by low-level gamma-ray spectrometry of the activated disks and subsequent neutron spectrum unfolding. The technique is similar to foil activation but here the applied neutron fluence rates are much lower than usually in the case of foil activation. The detector has been tested in quasi mono-energetic neutron fields with fluence rates in the order of 1000-10000 cm-2 s-1, where the obtained spectra showed good agreement with spectra measured using a Bonner sphere spectrometer. The detector has also been tested using an AmBe source and at a neutron fluence rate of about 40 cm-2 s-1, again, a good agreement with the assumed spectrum was achieved

  12. Fast neutron activation dosimetry with TLDS

    Pearson, D.W.; Moran, P.R.

    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 inexpensive, extremely sensitive radiation detectors. The work of Mayhugh et al. (Proc. Third Int. Conf. on Luminescence Dosimetry, Riso Report 249, 1040, (1971)) showed that CaSO/sub 4/: DyTLDs could be used to measure the integrated dose from the decay of the radioactivity produced in the dosimeters by exposure to thermal neutrons. This neatly combines the activation detector and counter functions in one solid state device. This work has been expanded to fast neutron exposures and other TL phosphors. The reactions /sup 19/F(n, 2n)/sup 18/F, /sup 32/S(n,p)/sup 32/P, /sup 24/Mg(n,p)/sup 24/, and /sup 64/Zn(n,p)/sup 64/Cu were found useful for fast neutron activation in commercial TLDs. As each TLD is its own integrating decay particle counter, many activation measurements can be made at the same time. The subsequent readings of the TL signals can be done serially after the induced radioactivity has decayed, using only one TL reader. The neutron detection sensitivity is limited mainly by the number statistics of the neutron activations. The precision of the neutron measurement is within a factor of two of conventional foil activation for comparable mass detectors. Commercially available TLDs can measure neutron fluences of 10/sup 9/n/cm/sup 2/ with 10 percent precision.

  13. Fast neutron activation dosimetry with TLDS

    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 inexpensive, extremely sensitive radiation detectors. The work of Mayhugh et al. (Proc. Third Int. Conf. on Luminescence Dosimetry, Riso Report 249, 1040, (1971)) showed that CaSO4: DyTLDs could be used to measure the integrated dose from the decay of the radioactivity produced in the dosimeters by exposure to thermal neutrons. This neatly combines the activation detector and counter functions in one solid state device. This work has been expanded to fast neutron exposures and other TL phosphors. The reactions 19F(n, 2n)18F, 32S(n,p)32P, 24Mg(n,p)24, and 64Zn(n,p)64Cu were found useful for fast neutron activation in commercial TLDs. As each TLD is its own integrating decay particle counter, many activation measurements can be made at the same time. The subsequent readings of the TL signals can be done serially after the induced radioactivity has decayed, using only one TL reader. The neutron detection sensitivity is limited mainly by the number statistics of the neutron activations. The precision of the neutron measurement is within a factor of two of conventional foil activation for comparable mass detectors. Commercially available TLDs can measure neutron fluences of 109n/cm2 with 10 percent precision

  14. Absolute Wavelength Control of Lasers for Active Sensing in Space Project

    National Aeronautics and Space Administration — We propose to develop compact absolute wavelength references to weak molecular transitions, which is a challenge characteristic to space-based active sensing. The...

  15. Fast-neutron activation analysis of manganese nodules

    The present paper describes the development of a new nuclear method that allows rapid determinations of the most relevant metals Ni and Cu without sample treatment, thus being particularly suited for quasi-continuous elemental analyses in mining and processing. The measurement is based on fast-neutron activation using Cockcroft-Walton generators, sealed neutron tubes or, possibly, (α,n)-type natural sources. Fast-neutron activation of manganese nodules is dominated by the (n,p)-reactions on Si, Al, Fe; the (n,α)-reaction on Mn and the (n,2n)-reaction on Cu. By choosing appropriate irradiation and cooling periods gamma-ray activities with comparatively simple spectral distributions are induced. From these spectra the Mn/Fe ratio in the nodules can be determined without the elaborate procedures usually required in absolute methods for eliminating systematic errors from fluctuations in sample and/or irradiation parameters. It is connected with the absolute Ni and Cu contents via well-known geochemical correlations which according to a lot of statistical data apply to quite different deposits and nodule types in the Pacific. Using these correlations the determination of the most important metals reduces to the evaluation of a peak area ratio. Measurements of the neutron flux distribution and the apparent sample density are unnecessary. The simple structure of the spectra allows the application of detectors with modest energy resolution, e.g. scintillation counters which can be manufactured as ruggedized crystal assemblies with great resistance to thermal and mechanical shock. The method is described in detail and possible interference, in particular from thermal and epithermal neutrons, are discussed. (orig.)

  16. DD neutron yield diagnosis by indium activation

    The measurement of DD neutron yield by activation is presented. This method is based on the inelastic scattering reaction of 115In with DD neutron, and the activated γ spectrum is counted by HPGe detector. The relation between the counts of detected y rays and the neutron yield is analyzed. The optimal thickness of sample is given by Monte Carlo simulation, which is 1 cm. The entire counting system has been calibrated on the K-400 accelerator. The result shows that the DD neutron measurement by indium activation can be used in the ICF experiment when the neutron yield is above 2 × 109. The total error of the system is below 10% in this condition. The total error will reduce when the neutron yield is larger. (authors)

  17. Manually controlled neutron-activation system

    Johns, R. A.; Carothers, G. A.

    1982-01-01

    A manually controlled neutron activation system, the Manual Reactor Activation System, was designed and built and has been operating at one of the Savannah River Plant's production reactors. With this system, samples can be irradiated for up to 24 hours and pneumatically transferred to a shielded repository for decay until their activity is low enough for them to be handled at a radiobench. The Manual Reactor Activation System was built to provide neutron activation of solid waste forms for the Alternative Waste Forms Leach Testing Program. Neutron activation of the bulk sample prior to leaching permits sensitive multielement radiometric analyses of the leachates.

  18. Testing Measurement Of Absolute Power Of The Dalat Nuclear Reactor By Neutron Noise Analysis

    In some recent years, technique of detection and analysis of neutron noise in nuclear reactor has been applied as a new method of experiment for studying physics characteristics of the Dalat nuclear reactor. This report will summarize the theoretical basis of the technique, instrumentation and experimental result in the low power range (0-50 W) of the Dalat nuclear reactor. (author)

  19. Absolute Measurement of 14C Activity by Internal Proportional Counters

    14CO22 was obtained by decomposing carbonate with sulphuric acid heated to boiling point, after which it was mixed with CH4 in a reserve flask. Three brass internal proportional counters, differing only in length, were filled with this mixture. The counters were connected to the electronic equipment in the usual arrangement. The equipment dead time was determined by means of a modified two-source method, and the total volume of the equipment was obtained from the isothermic expansion of methane from a flask whose volume, together with that of the counters, had been determined by weighing a water filling. The wall effect was determined by measuring a 14CO2 + CH4 mixture at different pressures and by extrapolation to reciprocal pressure zero value; it was discovered that the wall-effect correction did not differ significantly from zero. The end effect was compensated for by using counters of different lengths so that the difference in plateau slope also did not differ significantly from zero. By the t-test power function it was estimated that the maximal error on a 0.01 significance level, caused by neglecting the wall-effect correction, amounted to ± 0.85% due to the end-effect correction (± 0.62% for the equipment used) having been neglected. The relation between wall, end and discrimination effects is discussed, and, in conclusion, the maximal errors from other sources are estimated; the total maximal error on a 0.01 significance level of the standard solution activity is computed as equal to ± 1.1%. (author)

  20. The synchronous active neutron detection assay system

    We have begun to develop a novel technique for active neutron assay of fissile material in spent nuclear fuel. This approach will exploit a 14-MeV neutron generator developed by Schlumberger. The technique, termed synchronous active neutron detection (SAND), follows a method used routinely in other branches of physics to detect very small signals in presence of large backgrounds. Synchronous detection instruments are widely available commercially and are termed ''lock-in'' amplifiers. We have implemented a digital lock-in amplifier in conjunction with the Schlumberger neutron generator to explore the possibility of synchronous detection with active neutrons. The Schlumberger system can operate at up to a 50% duty factor, in effect, a square wave of neutron yield. Results are preliminary but promising. The system is capable of resolving the fissile material contained in a small fraction of the fuel rods in a cold fuel assembly; it also appears resilient to background neutron interference. The interrogating neutrons appear to be non-thermal and penetrating. Work remains to fully explore relevant physics and optimize instrument design

  1. Prompt gamma activation analysis using mobile reactor neutron beam

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

  2. Antiausterity activity of arctigenin enantiomers: importance of (2R,3R)-absolute configuration.

    Awale, Suresh; Kato, Mamoru; Dibwe, Dya Fita; Li, Feng; Miyoshi, Chika; Esumi, Hiroyasu; Kadota, Shigetoshi; Tezuka, Yasuhiro

    2014-01-01

    From a MeOH extract of powdered roots of Wikstroemia indica, six dibenzyl-gamma-butyrolactone-type lignans with (2S,3S)-absolute configuration [(+)-arctigenin (1), (+)-matairesinol (2), (+)-trachelogenin (3), (+)-nortrachelogenin (4), (+)-hinokinin (5), and (+)-kusunokinin (6)] were isolated, whereas three dibenzyl-gamma-butyrolactone-type lignans with (2R,3R)-absolute configuration [(-)-arctigenin (1*), (-)-matairesinol (2*), (-)-trachelogenin (3*)] were isolated from Trachelospermum asiaticum. The in vitro preferential cytotoxic activity of the nine compounds was evaluated against human pancreatic PANC-1 cancer cells in nutrient-deprived medium (NDM), but none of the six lignans (1-6) with (2S,3S)-absolute configuration showed preferential cytotoxicity. On the other hand, three lignans (1*-3*) with (2R,3R)-absolute configuration exhibited preferential cytotoxicity in a concentration-dependent manner with PC50 values of 0.54, 6.82, and 5.85 microM, respectively. Furthermore, the effect of (-)- and (+)-arctigenin was evaluated against the activation of Akt, which is a key process in the tolerance to nutrition starvation. Interestingly, only (-)-arctigenin (1*) strongly suppressed the activation of Akt. These results indicate that the (2R,3R)-absolute configuration of (-)-enantiomers should be required for the preferential cytotoxicity through the inhibition of Akt activation. PMID:24660468

  3. Instrumental neutron activation analysis - a routine method

    This thesis describes the way in which at IRI instrumental neutron activation analysis (INAA) has been developed into an automated system for routine analysis. The basis of this work are 20 publications describing the development of INAA since 1968. (Auth.)

  4. Neutron activation analysis of reference materials

    The importance is pointed out of neutron activation analysis in the preparation of reference materials, and studies are reported conducted recently by UJV. Instrumental neutron activation analysis has been used in testing homogeneity and in determining 28 elements in newly prepared reference standards of coal fly ash designated ENO, EOP and ECH. For accuracy testing, the same method was used in the analysis of NBS SRM-1633a Trace Elements in Coal Fly Ash and IAEA CRM Soil-5 and RM Soil-7. Radiochemical neutron activation analysis was used in determining Cd, Cu, Mn, Mo, and Zn in biological materials NBS SRM-1577 Bovine Liver, Bowen's Kale and in IAEA RM Milk Powder A-11 and Animal Muscle H-4. In all instances very good precision and accuracy of neutron activation analysis results were shown. (author)

  5. Improvement Of The Absolute Activity Determination Technique Of '125I In The Thyroid

    A method for absolute determination of the activity of a 125I source based on the counting rate values of the 27 keV photons and the 54 keV coincidence photo-peak is given in the literature. We had shown in previous works, that this method, within certain limitations, diminishes the geometry dependence of the activity determination for 125I sources and for measuring the uptake of 125I in human thyroid. In the present work we present a farther improvement of the accuracy of the absolute determination method

  6. KFUPM fast neutron activation analysis facility

    A newly established Fast Neutron Activation Analysis facility at the Energy Research Laboratory is described. The facility mainly consists of a fast neutron irradiation station and a gamma ray counting station. Both stations are connected by a fast pneumatic sample transfer system which transports the sample from the irradiation station to the counting station in a short time of 3 s. The fast neutron activation analysis facility has been tested by measuring the 27A(n, α)24Na and 115In(n, n')115mIn cross sections at 14.8 and 2.5 MeV neutron energies, respectively. Within the experimental uncertainties, the measured cross sections for these elements agree with the published values. (orig.)

  7. Low geometry counter for the absolute measurement of the activity of alpha-emitting sources

    A low-geometry counter is described which allows the absolute determination of the activity for alpha-emitting sources. A Si implanted detector is used to obtain the spectrum of the sample. Two samples are measured with this counter and a 2 π gridded ion chamber. The results an their uncertainties for both instruments are discussed. (Author)

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

    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); Cooper, G. W.; Nelson, A. J. [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)

    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.

  9. Motor preparatory activity in posterior parietal cortex is modulated by subjective absolute value.

    Asha Iyer

    Full Text Available For optimal response selection, the consequences associated with behavioral success or failure must be appraised. To determine how monetary consequences influence the neural representations of motor preparation, human brain activity was scanned with fMRI while subjects performed a complex spatial visuomotor task. At the beginning of each trial, reward context cues indicated the potential gain and loss imposed for correct or incorrect trial completion. FMRI-activity in canonical reward structures reflected the expected value related to the context. In contrast, motor preparatory activity in posterior parietal and premotor cortex peaked in high "absolute value" (high gain or loss conditions: being highest for large gains in subjects who believed they performed well while being highest for large losses in those who believed they performed poorly. These results suggest that the neural activity preceding goal-directed actions incorporates the absolute value of that action, predicated upon subjective, rather than objective, estimates of one's performance.

  10. Systematic Uncertainties in the Spectroscopic Measurements of Neutron-Star Masses and Radii from Thermonuclear X-ray Bursts. III. Absolute Flux Calibration

    Guver, Tolga; Ozel, Feryal; Marshall, Herman; Psaltis, Dimitrios; Guainazzi, Matteo; Diaz-Trigo, Maria

    2015-01-01

    Many techniques for measuring neutron star radii rely on absolute flux measurements in the X-rays. As a result, one of the fundamental uncertainties in these spectroscopic measurements arises from the absolute flux calibrations of the detectors being used. Using the stable X-ray burster, GS 1826-238, and its simultaneous observations by Chandra HETG/ACIS-S and RXTE/PCA as well as by XMM-Newton EPIC-pn and RXTE/PCA, we quantify the degree of uncertainty in the flux calibration by assessing the...

  11. Applications of neutron activation analysis in industry

    Neutron activation analysis technique is discussed in brief. This technique is used for quality control of raw materials, process materials and finished products, as well as activities in research and development for the improvement of the products and new products. The uses of this technique in several experienced industries are mentioned (author)

  12. Carbon Activation Diagnostic for Tertiary Neutron Measurements

    Glebov, V.Yu.; Stoeckl, C.; Sangster, T.C.; Meyerhofer, D.D.; Radha, P.B.; Padalino, S.; Baumgart, L.; Fuschino, J.

    2003-03-28

    OAK B202 The yield of tertiary neutrons with energies greater than 20 MeV has been proposed to determine the high rho R of inertial confinement fusion targets. The activation of carbon is a valuable measurement technique because of its high reaction threshold, the availability of high-purity samples, and relatively low cost. The 12C(n,2n)11C reaction has a Q value of 18.7 MeV, well above the 14.1 MeV primary DT neutron energy. The isotope 11C decays with a half-life of 20.3 min and emits a positron, resulting in the production of two back-to-back, 511 keV gamma rays upon annihilation. The positron decay of 11C is nearly identical to the copper decay used in the activation measurements of 14.1 MeV primary DT yields; therefore, the present copper activation gamma-detection system can be used to detect the tertiary-produced carbon activation. Because the tertiary neutron yield is more than six orders of magnitude lower than primary neutron yield, the carbon activation diagnostic requires ultrapure carbon samples, free from any positron-emitting contamination. In recent years we have developed carbon purification, packaging, and handling procedures that minimize the contamination signal to a level low enough to use carbon activation for tertiary neutron measurements in direct-drive implosion experiments with DT cryogenic targets on OMEGA. Experimental results of contamination measurements in carbon samples performed on high-neutron-yield shots on OMEGA in 2001-2002 will be presented. A concept for implementing a carbon activation system on the National Ignition Facility (NIF)will be discussed.

  13. Neutron Activation analysis of waste water

    An instrumental neutron activation analysis for the simultaneous determination of chlorine, bromine, sodium, manganese, cobalt, copper, chromium, zinc, nickel, antimony and iron in waste water is described. They were determined in waste water samples under normal conditions by non-destructive neutron activation simultaneously using a suitable monostandard method. Standardized water samples were used and irradiated in polyethylene ampoules at a neutron flux of 1013 cm-2 s-1 for periods of 1 minute, 1 and 10 hours. A Ge hyperpure detector was used for your activity determination, with count times of 60, 180, 300 and 600 seconds. The obtained results show than the method can be utilized for the determination of this elements without realize anything previous treatment of the samples. (Author)

  14. A review of conventional explosives detection using active neutron interrogation

    Conventional explosives are relatively easy to obtain and may cause massive harm to people and property. There are several tools employed by law enforcement to detect explosives, but these can be subverted. Active neutron interrogation is a viable alternative to those techniques, and includes: fast neutron analysis, thermal neutron analysis, pulsed fast/thermal neutron analysis, neutron elastic scatter, and fast neutron radiography. These methods vary based on neutron energy and radiation detected. A thorough review of the principles behind, advantages, and disadvantages of the different types of active neutron interrogation is presented. (author)

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

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

  16. Provenience studies using neutron activation analysis: the role of standardization

    This paper covers the historical background of chemical analysis of archaeological artifacts which dates back to 1790 to the first application of neutron activation analysis to archaeological ceramics and goes on to elaborate on the present day status of neutron activation analysis in provenience studies, and the role of standardization. In principle, the concentrations of elements in a neutron-activated specimen can be calculated from an exact knowledge of neutron flux, its intensity, duration and spectral (energy) distribution, plus an exact gamma ray count calibrated for efficiency, corrected for branching rates, etc. However, in practice it is far easier to compare one's unknown to a standard of known or assumed composition. The practice has been for different laboratories to use different standards. With analyses being run in the thousands throughout the world, a great benefit would be derived if analyses could be exchanged among all users and/or generators of data. The emphasis of this paper is on interlaboratory comparability of ceramic data; how far are we from it, what has been proposed in the past to achieve this goal, and what is being proposed. All of this may be summarized under the general heading of Analytical Quality Control - i.e., how to achieve precise and accurate analysis. The author proposes that anyone wishing to analyze archaeological ceramics should simply use his own standard, but attempt to calibrate that standard as nearly as possible to absolute (i.e., accurate) concentration values. The relationship of Analytical Quality Control to provenience location is also examined

  17. Characterization of the TRIGA Mark III reactor for k0 neutron activation analysis

    The k0 standardization for instrumental neutron activation analysis is a relatively new nuclear analytical technique. It is extended i n more than 20 countries of the world with reactor facilities, including some from Latin America. The great advantages of this technique (low uncertainties, fast and massive analysis, no standard necessity) with respect to relative, absolute and radiochemical activation analysis, are the reason of it fast introduction in Geology, Medicine, Agriculture and other fields of applications. But for the k0 instrumental neutron activation analysis implementation, the good knowledge of some reactor neutron flux and isotopes characteristics is necessary. The non ideality of the epithermal neutron flux temperature (Tn) and the k0 factors for more than 20 isotopes were determinate in the 3 typical irradiation positions of the TRIGA Mark III reactor of the National Nuclear Research Institute, Salazar, Mexico, using different experimental methods with conventional and non-conventional monitors

  18. Design of Neutron Activation Analysis Laboratorium Room

    Base on the planning to increase of the research and service quality in the ''Neutron activation analysis'' (APN),the design of mentioned ''Neutron activation analysis laboratories room'' has been done in the multi purpose reactor G.A. Siwabessy. By the using the designed installation, the irradiation preparation and counting sample can be done. The design doing by determination of installation lay out and maximum particle contain in the air. The design installation required a unit of 1 HP blower, a unit of 1 HP split air condition and 2 units 1200 x 800 mm HEPA filter. This paper concluded that this design is feasible to fabricated

  19. Interferences in reactor neutron activation analyses

    It has been shown that interfering reactions may occur in neutron activation analyses of aluminum and zinc matrixes, commonly used in nuclear areas. The interferences analysed were: Al2713 (n, α) Na2411 and Zn6430 (n, p) Cu6429. The method used was the non-destructive neutron activation analysis and the spectra were obtained in a 1024 multichannel system coupled with a Ge(Li) detector. Sodium was detected in aluminum samples from the reactor tank and pneumatic transfer system. The independence of the sodium concentration in samples in the range of 0 - 100 ppm is shown by the attenuation obtained with the samples encapsulated in cadmium. (Author)

  20. Neutron activation analysis of geochemical samples

    The present paper will describe the work done at the Technical Research Centre of Finland in developing methods for the large-scale activation analysis of samples for the geochemical prospecting of metals. The geochemical prospecting for uranium started in Finland in 1974 and consequently a manually operated device for the delayed neutron activation analysis of uranium was taken into use. During 1974 9000 samples were analyzed. The small capacity of the analyzer made it necessary to develop a completely automated analyzer which was taken into use in August 1975. Since then 20000-30000 samples have been analyzed annually the annual capacity being about 60000 samples when running seven hours per day. Multielemental instrumental neutron activation analysis is used for the analysis of more than 40 elements. Using instrumental epithermal neutron activation analysis 25-27 elements can be analyzed using one irradiation and 20 min measurement. During 1982 12000 samples were analyzed for mining companies and Geological Survey of Finland. The capacity is 600 samples per week. Besides these two analytical methods the analysis of lanthanoids is an important part of the work. 11 lanthanoids have been analyzed using instrumental neutron activation analysis. Radiochemical separation methods have been developed for several elements to improve the sensitivity of the analysis

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

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

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

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

  3. New studies in forensic neutron activation analysis

    Three recently completed studies in forensic neutron activation analysis are reported: a study of 0.22-caliber rimfire cartridge primers, a large-scale study of shotgun pellets, and a new 5-element procedure for the analysis of bullet-lead and shotgun-pellet samples. (author) 12 refs

  4. New studies in forensic neutron activation analysis

    Earlier studies in forensic neutron activation analysis are being extended in This Laboratory. Three of these new studies are reported here: 1) a study of 0.22-caliber rimfire cartridge primers, 2) a large-scale study of shotgun pellets, and 3) a new 5-element procedure for the analysis of bullet-lead and shotgun-pellet samples. (author)

  5. Neutron activation analysis helps in picture attribution

    The neutron activation analysis application for obtaining the data useful for proper attribution of paintings has been presented on the base of several examples. The identification on this way of dye elements, pigments and other painting materials is an important element among the physico-chemical methods helping the attribution procedure of old painting objects

  6. Neutron Activation Analysis with k0 Standardization

    SCK-CEN's programme on Neutron Activation Analysis with k0-standardisation aims to: (1) develop and implement k0-standardisation method for NAA; (2) to exploit the inherent qualities of NAA such as accuracy, traceability, and multi-element capability; (3) to acquire technical spin-off for nuclear measurements services. Main achievements in 1997 are reported

  7. Passive neutron dosemeter with activation detector

    Valero L, C.; Banuelos F, A.; Guzman G, K. A.; Borja H, C. G.; Hernandez D, V. M.; Vega C, H. R., E-mail: fermineutron@yahoo.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2011-10-15

    A passive neutron dosemeter with {sup 197}Au activation detector has been developed. The area dosemeter was made as a 20.5 {phi} x 20.5 cm{sup 2} polyethylene moderator, with a polyethylene pug where a {sup 197}Au foil can be located either parallel or perpendicular to moderator axis. Using Monte Carlo methods, with the MCNP5 code. With the fluence response and the fluence-to-equivalent dose conversion coefficients from ICRP-74, responses to H*(10) were also calculated, these were compared against responses of commercially available neutron area monitors and dosemeters. (Author)

  8. Fast neutron activation measurement of concealed explosives

    Spectra of 0.511 MeV γ-ray of nitrogen and 6.13 MeV γ-ray of oxygen and their ratio are measured by using two neutron sourses of different yield for explosive or non-explosive materials. Sensitivity and detecting speed are determined. A planar distribution of the explosive or non-explosive materials with different contents of nitrogen and oxygen is given. The whole design and security of detection method of fast neutron activation analysis system is discussed for concealed explosives

  9. Absolute nuclear material assay

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  10. Absolute nuclear material assay

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  11. Muscle Activation During Exercise in Severe Acute Hypoxia: Role of Absolute and Relative Intensity

    Torres-Peralta, Rafael; Losa-Reyna, José; González-Izal, Miriam; Perez-Suarez, Ismael; Calle-Herrero, Jaime; Izquierdo, Mikel; Calbet, José A. L.

    2014-01-01

    Torres-Peralta, Rafael, José Losa-Reyna, Miriam González-Izal, Ismael Perez-Suarez, Jaime Calle-Herrero, Mikel Izquierdo, and José A.L. Calbet. Muscle activation during exercise in severe acute hypoxia: Role of absolute and relative intensity. High Alt Med Biol 15:472–482, 2014.—The aim of this study was to determine the influence of severe acute hypoxia on muscle activation during whole body dynamic exercise. Eleven young men performed four incremental cycle ergometer tests to exhaustion bre...

  12. Absolutely connected sets of standard radiation sources for dissemination of the activity unit

    Sealed gamma sources and plane beta sources to be used as reference standards have been produced in such a way that in connecting measurements certain corrections have been avoided (e.g. self-absorption) or can be eliminated (e.g. backscattering). The production of the radiation sources and the technique of absolute connection to the primary standard of the activity unit are described for one set of gamma and beta radiation sources each, and a survey of the standard radiation source sets available is given, considering nuclides, type of source, activity and measuring accuracy. (author)

  13. Easy Absolute Values? Absolutely

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

    The authors teach a problem-solving course for preservice middle-grades education majors that includes concepts dealing with absolute-value computations, equations, and inequalities. Many of these students like mathematics and plan to teach it, so they are adept at symbolic manipulations. Getting them to think differently about a concept that they…

  14. Fast-Neutron Surveys Using Indium-Foil Activation

    Stephens, Lloyd D.; Smith, Alan R.

    1958-08-13

    Activation of indium foils by thermal neutrons has been applied to measurement of fast-neutron fluxes. Foils are encased in paraffin spheres placed in cadmium boxes. The high-energy neutrons that penetrate the cadmium become thermal neutrons; the thermal-neutron flux is proportional to the incident fast-neutron flux over a range of about 20 kev to 20 Mev. The foils are removed from the boxes and counted on a methane-flow proportional counter. High instantaneous neutron fluxes are easily detected and counted by use of these foils. Many simultaneous measurements have been made easily by this method.

  15. Neutron spectra unfolding from measured detector activations

    Our knowledge of the neutron spectrum in irradiation facilities essentially rests on the calculation and on the unfolding resp. adjustment based on measured activations, more generally said reactions rates, since the other direct or indirect experimental methods here frequently are not applicable on account of technical reasons. In this situation the neutronic calculation by no means renders superfluous the unfolding because the measurements can confirm or possibly correct resp. improve the calculational results. The FORTRAN code SAND-MX2 is a contribution of the KFA to the international repertoire of unfolding codes. With regard to its contents it is one of the newer versions of the original code SAND-II which are presently used as SAND-II also in the laboratories of several countries as especially practice related unfolding calculational methods. This report may serve as an instruction manual for the routinely neutron spectrum unfolding by means of the code SAND-MX2. It appeared to us not to be superfluous in addition to the above mentioned aim also to give a general view of the present situation in unfolding technique and to touch shortly the other advanced methods because we believed thereby also to give a better understanding of the characteristic features of our programme. In some laboratories several of the here described calculational programmes are alternatively in current use for the purpose of giving a greater confidence to the result of the neutron spectrum unfolding in question. (orig.)

  16. Applications of neutron activation analysis technique

    The technique was developed as far back as 1936 by G. Hevesy and H. Levy for the analysis of Dy using an isotopic source. Approximately 40 elements can be analyzed by instrumental neutron activation analysis (INNA) technique with neutrons from a nuclear reactor. By applying radiochemical separation, the number of elements that can be analysed may be increased to almost 70. Compared with other analytical methods used in environmental and industrial research, NAA has some unique features. These are multi-element capability, rapidity, reproducibility of results, complementarity to other methods, freedom from analytical blank and independency of chemical state of elements. There are several types of neutron sources namely: nuclear reactors, accelerator-based and radioisotope-based sources, but nuclear reactors with high fluxes of neutrons from the fission of 235U give the most intense irradiation, and hence the highest available sensitivities for NAA. In this paper, the applications of NAA of socio-economic importance are discussed. The benefits of using NAA and related nuclear techniques for on-line applications in industrial process control are highlighted. A brief description of the NAA set-ups at CERT is enumerated. Finally, NAA is compared with other leading analytical techniques

  17. Absolute alpha activity measurements of some plants growing in monazite bearing soils in Sri Lanka

    Mahawatte, P.; Hewamanna, R. (Colombo Univ. (Sri Lanka). Radioisotope Centre)

    1991-01-01

    Deposits of monazite bearing soils occur along the Southwest, West and East Coasts of Sri Lanka. High levels of gamma activity in some plant species growing in the West Coast have been reported. The high levels were due to the presence of the daughter nuclides of {sup 232}Th, most of which are alpha emitters. Absolute alpha activity measurements of ash samples of some plants growing in monazite bearing soils were carried out using the alpha sensitive polymeric nuclear track detector CR-39. The values ranged from 60-1900 mBq/g and were in good agreement with the values obtained from conventional scintillation counting method. The activity concentration of {sup 228}Th in the ash samples was also calculated by measuring the activity concentration of emanated thoron trapped inside a glass bottle with the use of a CR-39 track detector. (author).

  18. Absolute alpha activity measurements of some plants growing in monazite bearing soils in Sri Lanka

    Deposits of monazite bearing soils occur along the Southwest, West and East Coasts of Sri Lanka. High levels of gamma activity in some plant species growing in the West Coast have been reported. The high levels were due to the presence of the daughter nuclides of 232Th, most of which are alpha emitters. Absolute alpha activity measurements of ash samples of some plants growing in monazite bearing soils were carried out using the alpha sensitive polymeric nuclear track detector CR-39. The values ranged from 60-1900 mBq/g and were in good agreement with the values obtained from conventional scintillation counting method. The activity concentration of 228Th in the ash samples was also calculated by measuring the activity concentration of emanated thoron trapped inside a glass bottle with the use of a CR-39 track detector. (author)

  19. Absolute measurements of the alpha-gamma emitters activities by a sum-coincidence method

    The absolute activity of U-235 contained in a UO2 sample, using a sum-coincidence circuit which selected only the alpha particles which were simultaneous with the well known 184 Kev gamma radiation from Th-231. The alpha particles were detected by ZnS(Ag) scintillator specially designed to show its maximun efficiency for U-235 alpha particles, whereas the gamma radiation was detected by NaI(Tl) scintillation detector. The values obtained for the half-life of U-235 was compared with data from various observers using different experimental techniques. (Author)

  20. Neutron activation analysis of biological substances

    A Bowen cabbage sample was used as a reference material for the neutron activation studies, and the method was checked by the analysis of other biological substances (blood or serum etc.). For nondestructive measurements also some non-trace elements were determined in order to decide whether the activation analysis is a useful means for such measurements. The new activation analysis procedure was used for biomedical studies as, e.g., for trace element determination in body fluids, and for the analysis of inorganic components in air samples. (R.P.)

  1. Neutron activation analysis of geothermal water

    Instrumental technique of determination of 16 microimpurities in geothermal water samples is worked out. Probes and standard samples with cadmium filter have been irradiated by the thermal neutron flux of 5x1013 neutr.xcm-2xc-1. Cadmium filter permitted to considerably decrease 24Na radio activity caused by its high content in geothermal water, and to measure radioactivity in several hours after irradiation. Radioactivity measurement has been carried out without probe unpacking

  2. Reactor neutron activation analysis of industrial materials

    The specific application of neutron activation analysis (n.a.a.) for industrial materials is demonstrated by the determination of impurities in BeO, Al, Si, Cu, Ge, GaP, GaAs, steel, and irradiated uranium. A group scheme gives an orientation about the possibilities of n.a.a. The use of different standards, methods for the measurement of low radioactivities and errors caused by recoil reaction and radiation stimulated diffusion are discussed. (author)

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

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

  4. Multielement analysis of archaic Chinese bronze and antique coins by fast neutron activation analysis

    Samples of archaic bronze have been investigated by fast neutron activation analysis using both the absolute and relative method. The components Cu, Zn, Sn and Pb have been determined quantitatively. For the detection of lead via the short-lived isomeric state 207mPb, cyclic activation and measurement technique was used with pneumatic sample transfer between detector and central irradiation position of the neutron tube. For non-destructive analysis of antique Chinese coins the samples had to be irradiated outside the neutron generator KORONA. The activation reactions, the evaluation of the elemental concentrations and the accuracy of the results are discussed. The data were corrected for γ-ray self-absorption in the samples and summing of coincident γ-rays in the detector. According to reported typical compositions of Chinese bronze from different dynasties, the age of the samples has been derived from the results obtained. (orig.)

  5. Multielement analysis of archaic Chinese bronze and antique coins by fast neutron activation analysis

    Tian, Y.H. (Academia Sinica, Lanzhou, Gansu (China). Inst. of Modern Physics); Pepelnik, R.; Fanger, H.U. (GKSS-Forschungszentrum Geesthacht GmbH, Geesthacht-Tesperhude (Germany, F.R.). Inst. fuer Physik)

    1990-01-01

    Samples of archaic bronze have been investigated by fast neutron activation analysis using both the absolute and relative method. The components Cu, Zn, Sn and Pb have been determined quantitatively. For the detection of lead via the short-lived isomeric state {sup 207m}Pb, cyclic activation and measurement technique was used with pneumatic sample transfer between detector and central irradiation position of the neutron tube. For non-destructive analysis of antique Chinese coins the samples had to be irradiated outside the neutron generator KORONA. The activation reactions, the evaluation of the elemental concentrations and the accuracy of the results are discussed. The data were corrected for {gamma}-ray self-absorption in the samples and summing of coincident {gamma}-rays in the detector. According to reported typical compositions of Chinese bronze from different dynasties, the age of the samples has been derived from the results obtained. (orig.).

  6. Coincidence system for the absolute measurement of radionuclides activity using a liquid scintillator

    A system for the standartization of radioisotopes activity using liquid scintillator detector was developed. The system was set up at Nuclear Metrology Laboratory - L.M.N. (Nuclear Physics Division - IEA). The system performance was checked by absolute activity measurements for two radioisotopes, 60Co and 241Am. The activities were determined by the 4π(α, β-γ) coincidence method. An accuracy of the order of 99,8% was obtained. The results for 60Co were compared with those obtained by 4πβ-γ coincidence method using a proportional counter at L.M.N., while the results for 241Am were compared with those obtained through the linear extrapolation method using the same liquid scintillator. Compared to other systems, the advantages of this one are the simplicity and the short time spent in the sample preparation, and the negligible self-absorption. (Author)

  7. Active Vibration Isolation Using a Voice Coil Actuator with Absolute Velocity Feedback Control

    Yun-Hui Liu

    2013-11-01

    Full Text Available This paper describes the active vibration isolation using a voice coil actuator with absolute velocity feedback control for highly sensitive instruments (e.g., atomic force microscopes which suffer from building vibration. Compared with traditional isolators, the main advantage of the proposed isolation system is that it produces no isolator resonance. The absolute vibration velocity signal is acquired from an accelerator and processed through an integrator, and is then input to the controller as a feedback signal. The controller output signal then drives the voice coil actuator to produce a sky-hook damper force. In practice, the phase response of the integrator at low frequencies (2~6 Hz deviates from 90 degree which is the exact phase difference between the vibration velocity and acceleration. Therefore, an adaptive filter is used to compensate for the phase error. Analysis of this active vibration isolation system and comparison of model predictions to experimental results indicate that the proposed method significantly reduces transmissibility at resonance without incurring increased transmissibility at higher frequencies.

  8. Determination of the absolute activity by the coincidences 4πβ-γ method

    The 4π beta-gamma coincidence method for absolute determination of activities is extremely important in the production of high-precision radioactive sources. By means of this method it is possible to obtain absolute measurements of decay to within 0.1%. Thanks to the high efficiency of the 4π counter, most of the corrections required - background, random coincidences, dead time, decay scheme and detector efficiency - are small. The paper describes the experimental set-up showing the pulses in the two branches of the system, together with the conditions under which the 4πbeta flux detector functions. To determine whether the system was functioning satisfactorily, the activity of four cobalt-60 standards (supplied by the International Bureau of Weights and Measures based at Sevres in France) was determined and the differences obtained were less than 0.5% with respect to the certificates accompanying the sources. Alterations to the flux detector are suggested so that higher accuracy may be obtained. (author)

  9. Active neutron/photon personal dosemeters

    Though active personal dosemeters for photon fields reflect already a high level of development, there is still a need to advance the design of dosemeters for use in mixed neutron/photon fields and especially for monitoring the staff of nuclear power plants and the personnel accompanying transports of spent fuel flasks. The measurement of the neutron component is usually associated with problems. After a short description of the complex mixed fields in the nuclear fuel cycle, the commercially available active dosemeters and those under development will be listed and problems arising from their use in these fields will be discussed. Two new developments, the Siemens EPD-N2 and the PTB DOS-2002, which both are capable of indicating neutron and photon doses, will be described and discussed in detail. New response functions with respect to personal dose equivalent Hp(10) will be presented for neutrons. They have been determined by measurements in the quasi-monoenergetic reference fields at PTB in the energy range from 24 keV to 14.8 MeV and in fields with broad spectral distributions using the radionuclide sources 252Cf(bare), 252Cf(D2O,mod) - with and without cadmium shielding - 241Am-Be as well as a thermal neutron beam. The spectral distributions of all fields and the readings of the dosemeters in these fields were taken as inputs for an unfolding procedure to determine the dosemeter response in the overall energy region from thermal to 15 MeV. The procedure was tested by folding the dosemeter response with the broad neutron spectra and comparing with the readings of the dosemeters. Another problem in practical workplace fields is linked with high energy photons. Photons with energies from 6 MeV to 7 MeV from the 16O(n,pγ) reaction contribute to dose, particularly at reactors, and have to be taken into account when dosemeters are processed. Measurements with high energy photons were therefore performed with both devices and will be discussed. Finally, practical

  10. Neutron activation analysis of geological materials

    Neutron activation analysis (NAA) is an extremely sensitive, selective and precise method, which yields a wealth of elemental information from even a small-sized sample. With the recent advances in nuclear reactors and high-efficiency and high-resolution semiconductor detectors, NAA has become a powerful method for multielemental analysis. The concentration of major, minor, and trace elements vary from 1 to 4 orders of magnitude in geological materials. By varying neutron fluxes, irradiation times, decay and counting intervals and using both instrumental and radiochemical techniques in NAA, it is possible to accurately determine about 50 elements in a sample aliquant. The practical aspects of the NAA method as applied to geological materials are discussed in detail, and are demonstrated by the analysis of the United States Geological Survey (USGS) and the International Atomic Energy Agency (IAEA) standard reference geological materials. General aspects of the elemental interpretations in terrestrial samples are also discussed. (author)

  11. Absolute measurement of anti ν/sub p/ for 252Cf using the ORNL large liquid scintillator neutron detector

    The ORNL large liquid scintillator detector was used in a precise determination of anti ν/sub p/, the number of neutrons emitted promptly, for spontaneous fission of 252Cf. Measurements of the detector efficiency over a broad energy region were made by means of a proton-recoil technique employing the ORELA white neutron source. Monte Carlo calculation of the detector efficiency for a spectrum representative of 252Cf fission neutrons was calibrated with these elaborate measurements. The unusually flat response of the neutron detector resulted in elimination of several known sources of error. Experimental measurement was coupled with calculational methods to correct for other known errors. These measurements lead to an unusually small estimated uncertainty of 0.2% in the value obtained, anti ν/sub p/ = 3.773 +- 0.007

  12. Neutron activation analysis applied to archaeological problems

    Among the various techniques, the main analytical methods used to characterize ceramics are undoubtedly XRF and INAA. The principles of NAA differ from those of XRF in that samples are irradiated by thermal neutrons from a nuclear reactor. During irradiation, a few neutrons are captured by the nuclei of atoms in the specimen. This process, called activation, causes some of the nuclei to become unstable. During and after neutron irradiation, these unstable nuclei emit γ rays with unique energies at rates defined by the characteristic half-lives of the radioactive nuclei. Identification of the radioactive nucleus is possible by measuring the γ ray energies. Determination of their intensities permits quantitative analysis of the elements in the sample. The use of NAA in ceramics by a combination of two or three irradiation, decay and measurement strategies allows the determination of the elements Ba, Ce, Cl, Co, Cs, Dy, Eu, Fe, Hf, K, La, Lu, Mn, Na, Nd, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, U, Yb, Zn and Zr, if necessary by changing the irradiation, decay and measurement schemes. In general, XRF is more available, more rapid and less expensive than NAA. However, NAA offers a far greater number of elements, more sensitivity, superior precision and greater accuracy than XRF. On the other hand, NAA can be performed on extremely small samples (5-10 mg), meaning that only minor damage to valuable artefacts may be required

  13. The orientation effect in the activities of neutronic probes

    The formulae relating activity and position of a neutron irradiated Indium foil, have been verified experimentally. Measurements with both thin and thick foils for epithermal neutrons and with thick foils for thermal neutrons have been carried out. The experimental results agree qualitatively with the theoretical predictions. (Author)

  14. Neutron activation analysis of zirconium niobium alloys

    Full text: One of the important problems in nuclear reactor projecting is the choice of constructional materials, which meet to the requirements concerned with function, technical characteristics and expected performance of the reactor construction. Also it is necessary to take into account change of their properties under the influence of intensive neutron radiation. Zirconium and zirconium-niobium alloys are used in nuclear engineering as a fuel cladding and both matrix and impurity composition have an influence on their performance capabilities.Under intensive neutron radiation high content of undesirable trace elements in constructional materials can cause forming long-lived radionuclides with high induced activity and hence severe problems may occur at service, control of the equipment and carrying out experiments. Therefore analytical control of component and impurity composition of these materials is an important problem.Neutron activation analysis (NAA) is one of multielemental and high sensitivity methods, which widely applied for the analysis of high purity materials. Prior experiments have shown that instrumental NAA is not suitable for analysis of Zr-Nb alloys due to strong induced matrix activity. Therefore we have developed radiochemical procedure for separation of impurities from matrix elements. Study of the literature data has shown that zirconium and niobium are good extracted from hydrochloric medium by 0 75 M solution of di-2-ethylhexylphosphoric acid (DEHPA) in ortho-xylene. Also this system good extracts hafnium which being accompanying element has high content and interferes with determining impurity elements. To improve separation efficiency we have used 'DEHPA - ZM HCl' chromatography system. On the basis of the carried out researches the radiochemical NAA technique for analysis of high purity zirconium and zirconium-niobium alloys has been developed. The technique is based on extraction-chromatographic separation of matrix radionuclides

  15. Support system for Neutron Activation Analysis

    In the research reactor of JAERI, the Neutron Activation Analysis (NAA) has been utilized as a major part of an irradiation usage. To utilize NAA, research participants are always required to learn necessary technique. Therefore, we started to examine a support system that will enable to carry out INAA easily even by beginners. The system is composed of irradiation device, gamma-ray spectrometer and data analyzing instruments. The element concentration is calculated by using KAYZERO/SOLCOI software with the K0 standardization method. In this paper, we review on a construction of this INAA support system in JRR-3M of JAERI. (author)

  16. Toxicological applications of neutron-activation analysis

    Thermal neutron-activation analysis is recognised as a useful tool for trace element studies in toxicology. This paper describes some recent applications of the technique to three elements when ingested by people in excess of normal intake Two of the elements (copper and chromium) are essential to life and one (bromine) is as yet unclassified. Three deaths were investiagted and trace element levels compared with normal levels from healthy subjects in the same geographical area who had died as a result of violence. (author)

  17. Quality assurance in biomedical neutron activation analysis

    The summary report represents an attempt to identify some of the possible sources of error in in vitro neutron activation analysis of trace elements applied to specimens of biomedical origin and to advise on practical means to avoid them. The report is intended as guidance for all involved in analysis, including sample collection and preparation for analysis. All these recommendations constitute part of quality assurance which is here taken to encompass the two concepts - quality control and quality assessment. Quality control is the mechanism established to control errors, while quality assessment is the mechanism used to verify that the analytical procedure is operating within acceptable limits

  18. Neutron activation analysis of medicinal plant extracts

    Instrumental neutron activation analysis was applied to the determination of the elements Br, Ca, Cl, Cs, Fe, K, La, Mg, Mn, Na, Rb and Zn in medicinal extracts obtained from Centella asiatica, Citrus aurantium L., Achyrolcline satureoides DC, Casearia sylvestris, Solano lycocarpum, Zingiber officinale Roscoe, Solidago microglossa and Stryphnondedron barbatiman plants. The elements Hg and Se were determined using radiochemical separation by means of retention of Se in HMD inorganic exchanger and solvent extraction of Hg by bismuth diethyldithiocarbamate solution. Precision and accuracy of the results were evaluated by analyzing biological reference materials. The therapeutic action of some elements found in plant extracts analyzed is briefly discussed. (author). 15 refs., 5 tabs

  19. Rapid radiochemical separations in neutron activation analysis

    Rapid radiochemical separation procedures based on the removal of metal ions by columns of C18-bonded silica gel after selective complexation are examined and the simplicity of the method demonstrated by its application to the determination of Mn, Cu and Zn in neutron-activated biological material. The method is rapid and reliable and readily adaptable in all radiochemical laboratories. An alternative separation procedure for selenium in blood plasma involving desalination and concentration of the selenium protein complex by gel filtration or ultrafiltration is briefly discussed. (author)

  20. Neutron activation analysis of Etruscan pottery

    Neutron activation analysis (NAA) has been widely used in archaeology for compositional analysis of pottery samples taken from sites of archaeological importance. Elemental profiles can determine the place of manufacture. At Cornell, samples from an Etruscan site near Siena, Italy, are being studied. The goal of this study is to compile a trace element concentration profile for a large number of samples. These profiles will be matched with an existing data bank in an attempt to understand the place of origin for these samples. The 500 kW TRIGA reactor at the Ward Laboratory is used to collect NAA data for these samples. Experiments were done to set a procedure for the neutron activation analysis with respect to sample preparation, selection of irradiation container, definition of activation and counting parameters and data reduction. Currently, we are able to analyze some 27 elements in samples of mass 500 mg with a single irradiation of 4 hours and two sequences of counting. Our sensitivity for many of the trace elements is better than 1 ppm by weight under the conditions chosen. In this talk, details of our procedure, including quality assurance as measured by NIST standard reference materials, will be discussed. In addition, preliminary results from data treatment using cluster analysis will be presented. (author)

  1. Activities induced in the human body by thermal neutrons

    Activities of 17 radionuclides induced in the human body by the activation of 14 elements with thermal neutrons were calculated. Resulting dependences of these activities on the activation time are shown in graphs. (author)

  2. Absolute shifts of Fe I and Fe II lines in solar active regions (disk center)

    Brandt, P N; Sheminova, V A

    2010-01-01

    We estimated absolute shifts of Fe I and Fe II lines from Fourier-transform spectra observed in solar active regions. Weak Fe I lines and all Fe II lines tend to be red-shifted as compared to their positions in quiet areas, while strong Fe I lines, whose cores are formed above the level $\\log \\tau_5\\approx-3$ (about 425 km), are relatively blue-shifted, the shift growing with decreasing lower excitation potential. We interpret the results through two-dimensional MHD models, which adequately reproduce red shifts of the lines formed deep in the photosphere. Blue shifts of the lines formed in higher layer do not gain substance from the models.

  3. Total synthesis and absolute configuration assignment of MRSA active garcinol and isogarcinol.

    Socolsky, Cecilia; Plietker, Bernd

    2015-02-01

    A short total synthesis of (±)-garcinol and (±)-isogarcinol, two endo-type B PPAPs with reported activity against methiciline resistant Staphylococcus aureus (MRSA), is presented. The separation of framework-constructing from framework-decorating steps and the application of two highly regio- and stereoselective Pd-catalysed allylations, that is, the Pd-catalysed decarboxylative Tsuji-Trost allylation and the diastereoselective Pd-catalysed allyl-allyl cross-coupling, are key elements that allowed the total synthesis to be accomplished within 13 steps starting from acetylacetone. After separation of the enantiomers the absolute configurations of the four natural products (i.e., (-)-garcinol, (+)-guttiferone E (i.e., ent-garcinol), (-)-isogarcinol, and (+)-isoxanthochymol (i.e., ent-isogarcinol)) were assigned based on ECD spectroscopy. PMID:25537962

  4. Reactor neutron activation for multielemental analysis

    Neutron Activation Analysis using single comparator (K0 NAA method) has been used for obtaining multielemental profiles in a variety of matrices related to environment. Gold was used as the comparator. Neutron flux was characterised by determining f, the epithermal to thermal neutron flux ratio and cc, the deviation from ideal shape of the neutron spectrum. The f and a were determined in different irradiation positions in APSARA reactor, PCF position in CIRUS reactor and tray rod position in Dhruva reactor using both cadmium cut off and multi isotope detector methods. High resolution gamma ray spectrometry was used for radioactive assay of the activation products. This technique is being used for multielement analysis in a variety of matrices like lake sediments, sea nodules and crusts, minerals, leaves, cereals, pulses, leaves, water and soil. Elemental profiles of the sediments corresponding to different depths from Nainital lake were determined and used to understand the history of natural absorption/desorption pattern of the previous 160 years. Ferromanganese crusts from different locations of Indian Ocean were analysed with a view to studying the distribution of some trace elements along with Fe and Mn. Variation of Mn/Fe ratio was used to identify the nature of the crusts as hydrogenous or hydrothermal. Fe-rich and Fe-depleted nodules from Indian Ocean were analysed to understand the REE patterns and it is proposed that REE-Th associated minerals could be the potential Th contributors to the sea water and thus reached ferromanganese nodules. Dolomites (unaltered and altered), two types of serpentines and intrusive rock dolerite from the asbestos mines of Cuddapah basin were analysed for major, minor and trace elements. The elemental concentrations are used for distinguishing and characterising these minerals. From our investigations, it was concluded that both dolomite and dolerite contribute elements in the serpentinisation process. Chemical neutron

  5. Silicate rock and rock forming mineral neutron activation analysis

    A neutron-activation scheme for the determination of nine rare earths and other trace elements in various rock forming minerals (feldspars, ilmenite, magnetite, pyroxenes) and silicate rocks is presented. The procedure is based on three different irradiations involving three separate samples: - epithermal neutron irradiation (2 days) followed by nondestructive analysis; - thermal neutron irradiation (1 day) followed by instrumental analysis; - thermal neutron irradiation (1 week) followed by radiochemical analysis (precipitation, anion exchange separation, liquid-liquid extraction). Two USGS reference samples - granite G-2 and andesite AGV-1 - have been analysed in order to assess the accuracy of the proposed procedure. Our results agree with previous neutron-activation data. (orig.)

  6. Medical chemistry of boron neutron capture agents having pharmacological activity

    Boron neutron capture therapy (BNCT) is a cancer treatment that selectively destroys cancer cells following administering a cancer-selective drug containing stable isotope boron-10 and neutron irradiation. In clinical trial of BNCT, disodium mercaptoundecahydro-closo-dodecaborate (BSH) and p-boronophenylalanine (BPA) have been used, however, development of a new drugs with high cancer selectivity and therapeutic efficiency is expected. Therefore, we review boron-containing drugs as a boron neutron capture agents having pharmacological activity, BNCT research on boron-modified porphyrin derivatives which have photosensitivity and neutron capture activity and our proposed neutron sensitizing agent. (author)

  7. Medical application of in vivo neutron activation analysis

    Cohn, S.H.; Ellis, K.J.; Vartsky, D.; Zanzi, I.; Aloia, J.F.

    1978-01-01

    The clinical usefulness of total body neutron activation analysis (TBNAA) was clearly established at an IAEA panel meeting in Vienna in 1972. It is best demonstrated by the studies involving the measurement of total-body calcium. This measurement provides data useful for the diagnosis and management of metabolic bone disorders. It should be emphasized, however, that while most of the applications to date have involved calcium and phosphorus, the measurement of sodium, chlorine and nitrogen also appear to be useful clinically. Total-body calcium measurements utilizing TBNAA have been used in studies of osteoporosis to establish absolute and relative deficits of calcium in patients with this disease in comparison to a normal contrast population. Changes in total-body calcium (skeletal mass) have also been useful for quantitating the efficacy of various therapies in osteoporosis. Serial measurements over periods of years provide long-term balance data by direct measurement with a higher precision (+- 2%) than is possible by the use of any other technique. In the renal osteodystrophy observed in patients with renal failure, disorders of both calcium and phosphorus, as well as electrolyte disturbances, have been studied. The measure of total-body levels of these elements gives the clinician useful data upon which to design dialysis therapy. The measurement of bone changes in endocrine dysfunction has been studied, particularly in patients with thyroid and parathyroid disorders. In parathyroidectomy, the measurement of total-body calcium, post-operatively, can indicate the degree of bone resorption. Skeletal metabolism and body composition in acromegaly and Cushing's disease have also been investigated by TBNAA. Levels of cadmium in liver and kidney have also been measured in-vivo by prompt-gamma neutron activation and associated with hypertension, emphysema and cigarette smoking.

  8. Medical application of in vivo neutron activation analysis

    The clinical usefulness of total body neutron activation analysis (TBNAA) was clearly established at an IAEA panel meeting in Vienna in 1972. It is best demonstrated by the studies involving the measurement of total-body calcium. This measurement provides data useful for the diagnosis and management of metabolic bone disorders. It should be emphasized, however, that while most of the applications to date have involved calcium and phosphorus, the measurement of sodium, chlorine and nitrogen also appear to be useful clinically. Total-body calcium measurements utilizing TBNAA have been used in studies of osteoporosis to establish absolute and relative deficits of calcium in patients with this disease in comparison to a normal contrast population. Changes in total-body calcium (skeletal mass) have also been useful for quantitating the efficacy of various therapies in osteoporosis. Serial measurements over periods of years provide long-term balance data by direct measurement with a higher precision (+- 2%) than is possible by the use of any other technique. In the renal osteodystrophy observed in patients with renal failure, disorders of both calcium and phosphorus, as well as electrolyte disturbances, have been studied. The measure of total-body levels of these elements gives the clinician useful data upon which to design dialysis therapy. The measurement of bone changes in endocrine dysfunction has been studied, particularly in patients with thyroid and parathyroid disorders. In parathyroidectomy, the measurement of total-body calcium, post-operatively, can indicate the degree of bone resorption. Skeletal metabolism and body composition in acromegaly and Cushing's disease have also been investigated by TBNAA. Levels of cadmium in liver and kidney have also been measured in-vivo by prompt-gamma neutron activation and associated with hypertension, emphysema and cigarette smoking

  9. Epithermal neutron activation analysis of food

    Food samples were irradiated with thermal and epithermal neutrons. The average ratios of thermal to epithermal activity were determined for 80Br, 49Ca, 38Cl, 60mCo, 42K, 27Mg, 56Mn, 24Na, and 86mRb. They were equal to 2.1, 26, 24, 6.6, 19, 16, 11, 23 and 1.9, respectively. Then, 57 food samples were analyzed by epithermal neutron activation analysis for Br and Rb. The concentrations (in ppm) of Br and Rb were in asparagus (2) 2.3, 11.5; beets (3) 0.5, 0.8; beef (3) 1.7, 3.6; cabbage (5) 0.5, 10.8; carrot (3) 0.2, 3.7; chicken (3) 0.6, 4.4; chocolate (7) 11.1, 18.7; egg (3) 0.9, 1.9; french bean (3) 0.3, 1.0; goose (2) 1.3, 9.3; lettuce (2) 0.9, 1.7; pork (1) 1.5, 4.4; potato (7) 1.0, 1.2; sausage (3) 4.8, 3.5; spinach (3) 3.6, 4.0; strawberry jam (3) 0.4, 1.4; tomato (1) 13.5, 14.6; turkey (3) 1.2, 4.9. respectively. The number of samples and analyzed is indicated in parentheses. (author)

  10. Measurement of neutron flux spectra in a tungsten benchmark by neutron foil activation method

    The nuclear designs of fusion devices such as ITER (international thermonuclear experimental reactor), which is an experimental fusion reactor based on the ''tokamak'' concept, rely on the results of neutron physical calculations. These depend on the knowledge of the neutron and photon flux spectra which is particularly important because it permits to anticipate the possible answers of the whole structure to phenomena such as nuclear heating, tritium breeding, atomic displacements, radiation shielding, power generation and material activation. The flux spectra can be calculated with transport codes, but validating measurements are also required. An important constituent of structural materials and divertor areas of fusion reactors is tungsten. This thesis deals with the measurement of the neutron fluence and neutron energy spectrum in a tungsten assembly by means of multiple foil neutron activation technique. In order to check and qualify the experimental tools and the codes to be used in the tungsten benchmark experiment, test measurements in the D-T and D-D neutron fields of the neutron generator at Technische Universitaet Dresden were performed. The characteristics of the D-D and D-T reactions, used to produce monoenergetic neutrons, together with the selection of activation reactions suitable for fusion applications and details of the activation measurements are presented. Corrections related to the neutron irradiation process and those to the sample counting process are discussed, too. The neutron fluence and its energy distribution in a tungsten benchmark, irradiated at the frascati neutron generator with 14 MeV neutrons produced by the T(d,n)4He reaction, are then derived from the measurements of the neutron induced γ-ray activity in the foils using the STAYNL unfolding code, based on the linear least-squares-errors method, together with the IRDF-90.2 (international reactor dosimetry file) cross section library. The differences between the neutron flux

  11. Selected industrial and environmental applications of neutron activation analysis

    A review of the applications of Instrumental Neutron Activation Analysis (INAA) in the industrial and environmental fields is given. Detection limits for different applications are also given. (author)

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

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

  13. Measurement of U-235 absolute alpha value in the neutron energy range from 0.1 to 30 keV

    In order to measure the neutron-physical constants with high accuracy and to investigate ways of formation and decay of excited nuclei a method has been developed at the I.V. Kurchatov AEI, based on the gamma-quanta and neutrons multiplicity spectrometry. During 1974-1978 there have been constructed a number of multisectional 4π-detectors which have demonstrated great possibilities for this method. A detector permitting the required accuracy of measurements of neutron cross sections and their ratios has been chosen and designed on the basis of these works. The detector with 4π-geometry has 46 sections and was based on naI(Tl) crystals with the total volume of the scintillator of approx. 100 1. The detector was used at the 26-m station. The results of U-235 absolute alpha value measurements are presented. The measurements are carried out over the energy range from 0.1 to 30 keV with the high accuracy - better than 5%. The equipment parameters and measurement conditions are listed

  14. Activation Spectrometry of Fast Neutrons by IAEA Threshold Detectors at Neutron Generators

    The suitability of the IAEA set of threshold detectors for neutron accident purposes was investigated. A generator producing 14.3-MeV neutrons by the T(d, n)4He reaction was employed for this purpose. 237Np, 232Th, 58Ni and 27Al threshold detectors were used. The induced activity was determined by gamma spectrometry using a multichannel analyser. Fast neutron spectra have been estimated from the experimental results. Measurements at the surface and at the depth of a phantom were provided. Some difficulties from low induced and fission activities (caused by the small neutron flux density and the light weight of the detectors) are pointed out. (author)

  15. Estimation of thermal neutron flux from natZr activity

    Neutron transmutation doped (NTD) Ge thermistors are developed as low temperature thermometry (in mK range) in the cryogenic Tin bolometer, the India-based TIN detector (TIN.TIN). For this purpose, semiconductor grade Ge wafers are irradiated with thermal neutron at Dhruva reactor, BARC and dopant concentration critically depends on thermal neutron fluence. In order to obtain an independent estimate of the thermal neutron flux, natZr is used in one of the irradiations. The irradiated natZr samples have been studied in the Tifr Low background Experimental Setup (TiLES). The thermal neutron flux is estimated from the activity of 95Zr

  16. Industrial applications of neutron activation analysis

    Neutron activation analysis has been widely used in the industry and over the years played a key role in the development of manufacturing process as well as monitoring of the process flow. In this context NAA has been utilized both in R and D, and in the factory as a flexible analytical tool. It has been used successfully in numerous industries including broad categories such as Chemical, Pharmaceutical, Mining, Photographic, Oil and Gas, Automobile, Defense, Semiconductor and Electronic industries. Dow Chemical owns and operates a research reactor for analytical measurements of samples generated in both R and D, and manufacturing area in its plant in Midland, Michigan. Although most industries do not have reactors on their campus but use an off site reactor regularly, and often have in-house neutron sources such as a 252Cf used primarily for NAA. In most industrial materials analysis laboratory NAA is part of a number of analytical techniques such as ICP-MS, AA, SIMS, FTIR, XRF, TXRF etc. Analysis of complex industrial samples may require data from each of these methods to provide a clear picture of the materials issues involved. With the improvement of classical analytical techniques, and the introduction of new techniques, e.g. TXRF, the role of NAA continues to be a key bench mark technique that provides accurate and reliable data. The strength of the NAA in bulk analysis is balanced by its weakness in providing surface sensitive or spatially resolved analysis as is required by many applications. (author)

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

    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

  18. Computer modeling for neutron activation analysis methods

    Full text: The INP AS RU develops databases for the neutron-activation analysis - ND INAA [1] and ELEMENT [2]. Based on these databases, the automated complex is under construction aimed at modeling of methods for natural and technogenic materials analysis. It is well known, that there is a variety of analysis objects with wide spectra, different composition and concentration of elements, which makes it impossible to develop universal methods applicable for every analytical research. The modelling is based on algorithm, that counts the period of time in which the sample was irradiated in nuclear reactor, providing the sample's total absorption and activity analytical peaks areas with given errors. The analytical complex was tested for low-elemental analysis (determination of Fe and Zn in vegetation samples, and Cu, Ag and Au - in technological objects). At present, the complex is applied for multielemental analysis of sediment samples. In this work, modern achievements in the analytical chemistry (measurement facilities, high-resolution detectors, IAEA and IUPAC databases) and information technology applications (Java software, database management systems (DBMS), internet technologies) are applied. Reference: 1. Tillaev T., Umaraliev A., Gurvich L.G., Yuldasheva K., Kadirova J. Specialized database for instrumental neutron activation analysis - ND INAA 1.0, The 3-rd Eurasian Conference Nuclear Science and its applications, 2004, pp.270-271.; 2. Gurvich L.G., Tillaev T., Umaraliev A. The Information-analytical database on the element contents of natural objects. The 4-th International Conference Modern problems of Nuclear Physics, Samarkand, 2003, p.337. (authors)

  19. Large sample neutron activation analysis of a ceramic vase

    Stamatelatos, I.E.; Tzika, F.; Vasilopoulou, T.; Koster-Ammerlaan, M.J.J.

    2010-01-01

    Large Sample Neutron Activation Analysis (LSNAA) was applied to perform non-destructive elemental analysis of a ceramic vase. Appropriate neutron self-shielding and gamma ray detection efficiency calibration factors were derived using Monte Carlo code MCNP5. The results of LSNAA were compared against Instrumental Neutron Activation Analysis (INAA) results and a satisfactory agreement between the two methods was observed. The ratio of derived concentrations between the two methods was within 0...

  20. Neutron activation of gold dental restorations in small primates

    Zellmer, R.W.; Hartley, J.L.; Richey, E.O.; Harris, N.O.

    1959-07-01

    Dental gold alloys of various kinds were used to cast inlays which were placed in the molars of 10 small primates. These primates were then exposed to the neutron flux of an atomic detonation. The inlays were removed and the neutron-induced activity of the gold was measured in a scintillation counter. Calculation of the total activity showed a correlation with the neutron dosages received by the primates.

  1. Multielement analysis of archaic Chinese bronze and antique coins by fast neutron activation analysis

    Samples of archaic bronze were investigated by fast neutron activation analysis using both the absolute and relative method. The components Cu, Zn, Sn and Pb were determined quantitatively. For nondestructive analysis of antique Chinese coins the samples had to be irradiated. The activation reactions, the evaluation of the elemental concentrations and the accuracy of the results are discussed. The data were corrected for γ-ray self-absorption in the samples and summing of coincident γ-rays in the detector. According to reported typical compositions of Chinese bronze from different dynasties, the age of the samples has been derived from the results obtained. (author) 18 refs.; 3 figs.; 7 tabs

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

    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).

  3. Neutron activation in EBT-P

    Neutron activation due to photoneutron production in the lead shields proposed to protect the EBT-P superconducting coils from excessive x-ray heating was investigated. The photoneutron flux distribution in various EBT-P structural components was calculated for typical upgrade operating conditions using a standard two-dimensional transport model (TWOTRAN). Activity levels were then evaluated for major structural materials using activation cross sections tabulated in the GAMMON library. Activation dose rates in the device enclosure following several days of 8h/day upgrade (90GHz) operation were found to be approx. 6 mrem/h, decaying to <0.25 mrem/h in approx. 3 days. This requires radiation monitoring of all personnel entering the device enclosure during this time, but should not generally restrict hands on access to the device. There is thus no strong motivation to replace lead with another shield material; however, it may be desirable to borate the enclosure walls in order to reduce the effect which impurities might have on activity levels

  4. Measurements of absolute γ-ray intensities in the decays of very neutron rich isotopes of Cd and In

    The half lives and the γ-ray branching ratios of neutron rich Cd and In isotopes have been investigated by simultaneous measurements of β- and γ-ray spectra. The results presented contain information on 21 different β-decaying isotopes or isomers of Cd and In in the mass region A=123-129. Four previously unknown or little known isotopes of Cd are reliably characterized for the first time. (orig.)

  5. Neutron Activation Analysis of Biological Materials by Means of Neutron Multiplicator

    We have studied the possibilities of instrumental neutron activation analysis of freeze-dried biological materials performed with neutron multiplicator of average power (subcritical assembly PS-1). Neutron flux in the vertical channel amounts to 2.3*106n/cm2sec, concentrations of Na, Al and Mn were determined in freeze-dried samples of blue-green alga Spirulina platensis (S.platensis) (author)

  6. Comparison of activation in fission and fusion spectrum neutron beams

    The materials used in the construction of fusion reactors have to satisfy a number of criterions, one of the important being low activation due to neutron irradiation. Experimental analysis of the activation of candidate materials for the first wall is performed with the irradiation of samples in various neutron fields, frequently in the field of a fission reactor. In the present work a calculation is performed to compare the expected activation of candidate materials intended to be used for the first wall in fusion reactors with the activation of a sample of the same material in a fission reactor beam. The FISPACT code is used for activation calculations. An investigation, to what extent the results of activation in a fission spectrum neutron beam, where most neutrons have energies of less than 2 MeV, mimic the real situation in a fusion reactor with the peak neutron energy around 14 MeV, is performed. (author)

  7. Instrumental neutron activation analysis of soil sample

    This paper describes the analysis of soil samples collected from 5 different location around Sungai Lui, Kajang, Selangor, Malaysia. These sample were taken at 22-24 cm from the top of the ground and were analysed using the techniques of Instrumental Neutron Activation Analysis (INAA). The analysis on soil sample taken above 22-24 cm level were done in order to determine if there is any variation in elemental contents at different sampling levels. The results indicate a wide variation in the contents of the samples. About 30 elements have been analysed. The major ones are Na, I, Cl, Mg, Al, K, Ti, Ca and Fe. Trace elements analysed were Ba, Sc, V, Cr, Mn, Ga, As, Zn, Br, Rb, Co, Hf, Zr, Th, U, Sb, Cs, Ce, Sm, Eu, Tb, Dy, Yb, Lu and La. (author)

  8. Instrumental neutron activation analysis of kidney stones

    Kidney stone samples of the types calcium oxalate, uric acid, and xanthine were analyzed for their elemental contents by neutron activation analysis to study both the elemental correlation and influence of element on stone precipitation processes. Elements, such as Al, Au, Br, Ca, Cl, Co, Cr, Fe,H, I, K, Mg, Na, Sb, Se, Sr, and Zn, were determined quantitatively. Calcium oxalate stones contained higher concentration of all the elements analyzed compared to uric acid or xanthine stones. The concentrations of Cl, Fe, K, Na, Sr, and Zn were relatively higher than Au, Co, Cr, and Sb. A positive correlation exists between Ca and Zn, whereas a negative correlation exists between Sr and Ca. Zinc may play an important role in the formation of calcium oxalate stone

  9. Neutron activation analysis of human hair

    In an attempt to study the availability and limitation of analytical data of human hair as an indicator of environmental pollution and/or of human health effect, concentrations of elements in 202 scalp hair samples collected from local population in the Tokyo Metropolitan area were determined by instrumental neutron activation analysis. The correlation coefficients between concentrations of 13 elements in each sex and in each age group were calculated and discussed. There were significant correlations between some pairs of elements, i.e. Na-K, Br-Cl, Ca-Zn and Ca-Mg, in all five age classes in both of male and female, indicating that the correlations were consistent. Ca was observed to be reversely correlated with Cl. No significant correlation was apparent between Hg and Se, when the correlation coefficient was calculated using logarithmic converted concentration data. (author)

  10. Neutron activation analysis of urinary calculi

    Urinary calculi resulting from disorders in the urinary system are mostly composed of uric acid, urates, calcium oxalate, alkaline earth phosphates (Ca and Mg), triple phosphate (magnesium ammonium phosphate), calcium carbonate, cystine, xanthine, and traces of proteins. The determination of these macro-constituents has been carried out by different analytical procedures. No attempts however, have been reported regarding the determination of trace elements in urinary stones, apart from that of Herring et al., who investigated the consumption of strontium by urolithiasis patients. The present work is a non-destructive neutron activation analysis of urinary calculi, to search the variation in concentration of certain trace elements with the chemical composition of the calculus

  11. Measurements of fusion neutron yields by neutron activation technique: Uncertainty due to the uncertainty on activation cross-sections

    The neutron activation technique is routinely used in fusion experiments to measure the neutron yields. This paper investigates the uncertainty on these measurements as due to the uncertainties on dosimetry and activation reactions. For this purpose, activation cross-sections were taken from the International Reactor Dosimetry and Fusion File (IRDFF-v1.05) in 640 groups ENDF-6 format for several reactions of interest for both 2.5 and 14 MeV neutrons. Activation coefficients (reaction rates) have been calculated using the neutron flux spectra at JET vacuum vessel, both for DD and DT plasmas, calculated by MCNP in the required 640-energy group format. The related uncertainties for the JET neutron spectra are evaluated as well using the covariance data available in the library. These uncertainties are in general small, but not negligible when high accuracy is required in the determination of the fusion neutron yields

  12. Chemical weapons detection by fast neutron activation analysis techniques

    A neutron diagnostic experimental apparatus has been tested for nondestructive verification of sealed munitions. Designed to potentially satisfy a significant number of van-mobile requirements, this equipment is based on an easy to use industrial sealed tube neutron generator that interrogates the munitions of interest with 14 MeV neutrons. Gamma ray spectra are detected with a high purity germanium detector, especially shielded from neutrons and gamma ray background. A mobile shell holder has been used. Possible configurations allow the detection, in continuous or in pulsed modes, of gamma rays from neutron inelastic scattering, from thermal neutron capture, and from fast or thermal neutron activation. Tests on full scale sealed munitions with chemical simulants show that those with chlorine (old generation materials) are detectable in a few minutes, and those including phosphorus (new generation materials) in nearly the same time. (orig.)

  13. Development of educational program for neutron activation analysis

    This technical report is developed to apply an educational and training program for graduate student and analyst utilizing neutron activation analysis. The contents of guide book consists of five parts as follows; introduction, gamma-ray spectrometry and measurement statistics, its applications, to understand of comprehensive methodology and to utilize a relevant knowledge and information on neutron activation analysis

  14. Trace Analysis of Ancient Gold Objects Using Radiochemical Neutron Activation

    Olariu, A; Constantinescu, O; Badica, T; Popescu, I V; Besliu, C; Leahu, D; Olariu, Agata; Constantinescu, Mioara; Leahu, Doina

    1999-01-01

    Radiochemical neutron activation analysis has been applied to investigate the microelements in gold samples with archaeological importance. Chemical separation has allowed the determination of traces of Ir, Os, Sb, Zn, Co, Fe, Ni. Instrumental neutron activation analysis has been used for the determination of Cu.

  15. Development of educational program for neutron activation analysis

    Chung, Yong Sam; Moon, Jong Hwa; Kim, Sun Ha; Ryel, Sung; Kang, Young Hwan; Lee, Kil Yong; Yeon, Yeon Yel; Cho, Seung Yeon

    2000-08-01

    This technical report is developed to apply an educational and training program for graduate student and analyst utilizing neutron activation analysis. The contents of guide book consists of five parts as follows; introduction, gamma-ray spectrometry and measurement statistics, its applications, to understand of comprehensive methodology and to utilize a relevant knowledge and information on neutron activation analysis.

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

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

  17. Systematic Uncertainties in the Spectroscopic Measurements of Neutron-Star Masses and Radii from Thermonuclear X-ray Bursts. III. Absolute Flux Calibration

    Guver, Tolga; Marshall, Herman; Psaltis, Dimitrios; Guainazzi, Matteo; Diaz-Trigo, Maria

    2015-01-01

    Many techniques for measuring neutron star radii rely on absolute flux measurements in the X-rays. As a result, one of the fundamental uncertainties in these spectroscopic measurements arises from the absolute flux calibrations of the detectors being used. Using the stable X-ray burster, GS 1826-238, and its simultaneous observations by Chandra HETG/ACIS-S and RXTE/PCA as well as by XMM-Newton EPIC-pn and RXTE/PCA, we quantify the degree of uncertainty in the flux calibration by assessing the differences between the measured fluxes during bursts. We find that the RXTE/PCA and the Chandra gratings measurements agree with each other within their formal uncertainties, increasing our confidence in these flux measurements. In contrast, XMM-Newton EPIC-pn measures 14.0$\\pm$0.3% less flux than the RXTE/PCA. This is consistent with the previously reported discrepancy with the flux measurements of EPIC-pn, compared to EPIC-MOS1, MOS2 and ACIS-S detectors. We also address the calibration uncertainty in the RXTE/PCA int...

  18. Use of proportional gas scintillator in absolute measurements of alpha-gamma emitter activities

    The absolute activity of U-235 contained in a U3 O8 sample was measured utilizing a sum-coincidence circuit which selects only the alpha particles which are simultaneous with the 143 KeV and 186 KeV gamma radiations from the Th-231 (product nucleus). The alpha particles were detected by means of a new type of a gas scintillating chamber, in which the light emitted by excitation of the gas atoms, due to the passage of a charged incoming particle, has its intensity increased by the action of an applied electric field. The gamma radiations were detected by means of a NaI(Tl) 1'' x 11/2'' scintillation detector. The value obtained for the half-life of U-235 was compared with the data available from various observers which used different experimental techniques. It is shown tht the results, are in excellent agreement with the best international data available on the subject and that, therefore, the sum-coincidence technique constitutes an important method for such measurements. (Author)

  19. Active Neutron Interrogation and Delayed Neutron Counting (AIDNEC) for assay of 235U

    A method has been developed for non destructive assay of 235U using active neutron interrogation followed by delayed neutron counting (AIDNEC) system. The neutrons from a plasma focus (PF) device were used to bombard the samples containing low enriched uranium ranging from 13 mg to 5 g. The PF device generates (1.2±0.3) x109 D-D fusion neutrons per shot with a pulse width of 46±5 ns. The delayed neutrons were monitored using a bank of six 3He detectors. The sensitivity of the system was found to be about 1000 cps per gram over the accumulation time of 25 seconds per neutron pulse of ∼109. The detection limit of the system is estimated to be 18 mg of 235U. (author)

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

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

  1. Neutrons flux distribution in a 252Cf irradiation cell for neutron activation analysis

    A 100 microgram Californium-252 (252Cf) neutron source was embedded in a pure paraffin moderator surrounded by neutron and gamma ray shields to be used as an irradiation cell facility for NAA experiments. The cell is provided with a direct horizontal channel and a Vertical Tangential Irradiation Channel (VTIC) that are parallel to the source axis. The cadmium difference method was used in determining the thermal and epithermal neutron flux distributions along the axis of the (VTIC). For this purpose, 10 pairs of bare and cadmium covered pure gold foils were irradiated at the same positions along the axis of the (VTIC) in two separate runs. The absolute efficiency of the HPGe detector at the gamma ray energy 411.8 keV of 198 Au, was found to be 0.0318 ± 0.0025.The obtained distributions of thermal and epithermal neutron fluxes were tabulated and graphically presented. An evidence for contributions from 252Cf fission by epithermal neutrons was noticed. As an application on this facility the concentration of gold in an ore sample from gold - bearing ivory vein of wady Allaqui (at south west of eastern desert) was determined. It was found to be 612 ± 6 ppm

  2. Neutron activation diagnostics at the National Ignition Facility (invited).

    Bleuel, D L; Yeamans, C B; Bernstein, L A; Bionta, R M; Caggiano, J A; Casey, D T; Cooper, G W; Drury, O B; Frenje, J A; Hagmann, C A; Hatarik, R; Knauer, J P; Johnson, M Gatu; Knittel, K M; Leeper, R J; McNaney, J M; Moran, M; Ruiz, C L; Schneider, D H G

    2012-10-01

    Neutron yields are measured at the National Ignition Facility (NIF) by an extensive suite of neutron activation diagnostics. Neutrons interact with materials whose reaction cross sections threshold just below the fusion neutron production energy, providing an accurate measure of primary unscattered neutrons without contribution from lower-energy scattered neutrons. Indium samples are mounted on diagnostic instrument manipulators in the NIF target chamber, 25-50 cm from the source, to measure 2.45 MeV deuterium-deuterium fusion neutrons through the (115)In(n,n')(115 m) In reaction. Outside the chamber, zirconium and copper are used to measure 14 MeV deuterium-tritium fusion neutrons via (90)Zr(n,2n), (63)Cu(n,2n), and (65)Cu(n,2n) reactions. An array of 16 zirconium samples are located on port covers around the chamber to measure relative yield anisotropies, providing a global map of fuel areal density variation. Neutron yields are routinely measured with activation to an accuracy of 7% and are in excellent agreement both with each other and with neutron time-of-flight and magnetic recoil spectrometer measurements. Relative areal density anisotropies can be measured to a precision of less than 3%. These measurements reveal apparent bulk fuel velocities as high as 200 km/s in addition to large areal density variations between the pole and equator of the compressed fuel. PMID:23126840

  3. Neutron activation analysis and atomic absorption spectrophotometry for the analysis of fresh, pasteurised and powder milk

    Wasim, M.; Rehman, S.; Arif, M.; Fatima, I.; Zaidi, J.H. [Pakistan Inst. of Nuclear Science and Technology, Islamabad (Pakistan). Chemistry Div.

    2012-07-01

    This study shows the application of semi-absolute k{sub 0} instrumental neutron activation analysis (k{sub 0}-INAA), epithermal neutron activation analysis (ENAA) and atomic absorption spectrophotometry (AAS) for the determination of 21 elements (Br, Ca, Cl, Co, Cr, Cs, Cu, Fe, Hf, I, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sc Sr, and Zn) in different types of milk samples. The ENAA was required for the determination of iodine, AAS for Cu, Ni and Pb and the rest of the elements were measured by k{sub 0}-INAA. Thirteen elements (Br, Ca, Cl, Cs, Cu, Fe, K, Mg, Na, P, Rb, Sr and Zn) were identified in all milk samples. Ni was detected in eleven and Pb in two samples. Concentrations of most of the elements were within the ranges of the world reported data. The data was further explored by principal component analysis to find relationships between samples and elements. (orig.)

  4. Transmission and Reflection of Neutrons Using Foil Activation Technique

    A new neutron irradiation facility has been designed, constructed .and located at the Experimental Nuclear Physics Department, NRC, AEA, cairo. The neutrons were obtained from CNIF2 (Second Cairo Neutron Irradiation Facility) that is based on one 241 Am-Be(α, n) isotopic neutron source with a present activity of about 175 GBq results in a neutron yield of about 1.04 x107 n/s. The geometrical arrangements of the facility consider the safety and protection rules aspects. MCNP5 code is used to estimate radiation doses and neutron fluxes. This new irradiation facility provides fast and epithermal neutrons that can be used in basic research and industrial applications. The aim of the present work is to study the characteristics of this new irradiation facility and to develop methods able to use fast and epithermal neutron in some different applications. Experimental measurements for the transmission and reflection of neutrons were carried out via a number of hydrogenous materials using the activation foil technique. A comparison of the experimental results with that calculated by using Monte Carlo simulation method is presented Using the neutron transmission technique in combination with foil activation method, our arrangement is used to measure the total neutron microscopic cross-sections for some compounds. The facility is calibrated and suitable to estimate the hydrogen content H (wt %) and the weight ratios C/H in hydrocarbon materials and was used to measure these ratios for some Egyptian crude oil samples. A brief overview of the neutron activation analysis methods for elemental concentrations in bulk samples in natural conditions is presented.

  5. Layered shielding design for an active neutron interrogation system

    Whetstone, Zachary D.; Kearfott, Kimberlee J.

    2016-08-01

    The use of source and detector shields in active neutron interrogation can improve detector signal. In simulations, a shielded detector with a source rotated π/3 rad relative to the opening decreased neutron flux roughly three orders of magnitude. Several realistic source and detector shield configurations were simulated. A layered design reduced neutron and secondary photon flux in the detector by approximately one order of magnitude for a deuterium-tritium source. The shield arrangement can be adapted for a portable, modular design.

  6. Measurement of 14.8 MeV neutron flux of a neutron generator using neutron activation technique

    Fast neutron flux (14.8 MeV) of a neutron generator has been measured by activation technique. The measurements performed using Cu and Ni threshold detectors. 62Cu and 57Ni were produced through 63Cu(n,2n)62Cu and 58Ni (n,2n)57Ni reactions. They decay by emitting 511 keV and 1377 keV gamma rays. respectively. The half life of 62Cu is 9.74min and that of 57Ni is 36 hours. The flux of neutron has been calculated by measuring the activity after the irradiation time. Gamma spectroscopy of the activated foils was performed using a HPGe detector. By employing this technique the neutron flux of 2.64 107±3% n/s was obtained for 60 μA deuteron of 110 keV energy, bombarding a solid target of 3H

  7. Neutron activation analysis of human hair

    As a part of IAEA research project, ''Activation analysis of hair as an indicator of contamination of man by environmental trace element pollutants'', a survey was carried out to elucidate the levels of various trace element concentration in hair of local population in the Tokyo Metropolitan areas, by applying instrumental neutron activation analysis. A total of 202 scalp hair samples were collected from the inhabitants classified by sex and five age classes. Irradiation was made in the Rikkyo University 100 kW TRIGA MARK-II reactor. Using several combinations of irradiation time, cooling time and counting time, forty elements were determined. The relationship between several trace element contents in hair and such factors as sex, age class, hair treatment, smoking habit and dental treatment, was analyzed by using the method of multiple regression. It was shown that (1) Hair treatment had a predominant effect on the contents of bromine, magnesium and calcium in hair, (2) Aging and amoking contributed increasing mercury content in hair, and hair treatment acted reversely. (author)

  8. Neutron activation analysis of arsenic in Greece

    Arsenic is considered a toxic trace element for plant, animal, and human organisms. Arsenic and certain arsenic compounds have been listed as carcinogens by the U.S. Environmental Protection Agency. Arsenic is emitted in appreciable quantities into the atmosphere by coal combustion and the production of cement. Arsenic enters the aquatic environment through industrial activities such as smelting of metallic ores, metallurgical glassware, and ceramics as well as insecticide production and use. Neutron activation analysis (NAA) is a very sensitive, precise, and accurate method for determining arsenic. This paper is a review of research studies of arsenic in the Greek environment by NAA performed at our radioanalytical laboratory. The objectives of these studies were (a) to determine levels of arsenic concentrations in environmental materials, (b) to pinpoint arsenic pollution sources and estimate the extent of arsenic pollution, and (c) to find out whether edible marine organisms from the gulfs of Greece receiving domestic, industrial, and agricultural wastes have elevated concentrations of arsenic in their tissues that could render them dangerous for human consumption

  9. Neutron activation analysis of ancient silver coins

    The amounts of gold and copper present as impurities in 500 Creek silver coins of the fifth century B.C. have been determined with a gamma-ray spectrometer, following neutron activation. The coinage from eight cities and kingdoms was studied; the average gold-content for different groups of coins varies between 0.02% and 0.3%, and the copper content between 0.1% and 10%. Evidence about trading connexions and of deliberate debasements of the coinage has been obtained, and several unsuspected plated coins were detected. The gold content was determined by measuring the intensity of the 0.411 MeV gamma-ray from Au198 (2.69 d); for the copper content the 0.511 MeV positron annihilation radiation from Cu64 (12.8 h) was used, and for silver the 0.884 MeV gamma-ray from Ag110m (253 d). Decay measurements were used as a check of identity. The technique of using total gamma-activity decay curves by themselves is insufficiently sensitive. For accurate work, the importance of approximate facsimile standards is stressed. (author)

  10. Fast neutron activation analysis of ancient mirror

    About fifty specimens of ancient Chinese bronze mirror from various dynasties are analysed by fast neutron radiated from neutron generator. The contents of copper, tin and lead in the mirror are listed in this paper. Experimental method and measurement equipment are described too

  11. Neutron activation analysis (NAA), radioisotope production via neutron activation (PNA) and fission product gas-jet (GJA)

    Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1996-11-01

    Three different non-diffractive applications of neutrons are outlined, neutron activation analysis, production of radionuclides, mostly for medical applications, and production of short-lived fission nuclides with a so-called gas-jet. It is shown that all three devices may be incorporated into one single insert at SINQ due to their different requests with respect to thermal neutron flux. Some applications of these three facilities are summarized. (author) 3 figs., 1 tab., 8 refs.

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

    The Californium User Facility (CUF) for Neutron Science has been established to provide 252Cf-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 252Cf neutron sources. Neutron source intensities of ≤ 1011 neutrons/s are available for irradiations within a contamination-free hot cell, capable of providing thermal and fast neutron fluxes exceeding 108 cm-2 s-1 at the sample. Total flux of ≥109 cm-2 s-1 is feasible for large-volume irradiation rabbits within the 252Cf 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

  13. Neutron spectrum determination by activation method in fast neutron fields at the RB reactors

    The fast neutron fields of the RB reactor are presented in this paper. The activation method for spectrum determination is described and explained. The obtained results for intermediate and fast spectrum are given and discussed. (authors). 7 refs., 3 tabs

  14. Ten year's activity in the field of neutron scattering workshop

    'Neutron scattering' is in the frame of the 'Utilization of Research Reactor's of the FNCA (Forum for Nuclear Cooperation in Asia) project, which held the workshops from FY 1992. This report is a summary of the results and activities of neutron scattering workshops and sub-workshops since the start in FY 1992. (author)

  15. Progress in small angle neutron scattering activities in Malaysia

    Research activities by use of small angle neutron scattering in Malaysia are briefly reported. Scattered neutron data are displayed in two or three-dimensional isometric view by the data acquisition system. Visual Basic is utilized for data acquisition and MathCad for data processing and analyses. (Y. Kazumata)

  16. A synopsis of the activities on neutron standard reference data at the Institute of Atomic Energy

    The activities of neutron standard reference data including neutron standard cross section measurements, 252Cf spontaneous fission nubar and neutron energy spectrum measurements, neutron flux measurements, neutron source strength calibrations and neutron standard data evaluations carried out at the Institute of Atomic Energy, Beijing are presented. Some experimental results and recommended values are given

  17. Quality assurance in neutron activation analysis

    As a potential reference method, neutron activation analysis does not have to rely on other reference materials to ascertain the quality of analytical results. The fundamental characteristics of the method with the clear separation between irradiation, processing, and counting makes possible the estimation of uncertainties of individual results from a priori assumptions. Such estimates of the standard deviation from a series of independent sources of variation are compared with the a posteriori variability of replicate determinations in order to ascertain that the analytical method is in a state of statistical control. This Analysis of Precision tests the absence of unknown errors by means of a statistic T, which is closely approximated by a chi-square distribution. In this manner an evaluation is made of a commercially available computer program for peak evaluation in γ-spectrometry, as well as of other factors affecting the precision and accuracy of the counting process. An attempt is also made to determine sampling constants of one gram or less in a candidate biological reference material

  18. Epithermal neutron activation analysis in applied microbiology

    Some results from applying epithermal neutron activation analysis at FLNP JINR, Dubna, Russia, in medical biotechnology, environmental biotechnology and industrial biotechnology are reviewed. In the biomedical experiments biomass from the blue-green alga Spirulina platensis (S. platensis) has been used as a matrix for the development of pharmaceutical substances containing such essential trace elements as selenium, chromium and iodine. The feasibility of target-oriented introduction of these elements into S. platensis biocomplexes retaining its protein composition and natural beneficial properties was shown. The absorption of mercury on growth dynamics of S. platensis and other bacterial strains was observed. Detoxification of Cr and Hg by Arthrobacter globiformis 151B was demonstrated. Microbial synthesis of technologically important silver nanoparticles by the novel actinomycete strain Streptomyces glaucus 71 MD and blue-green alga S. platensis were characterized by a combined use of transmission electron microscopy, scanning electron microscopy and energy-dispersive analysis of X-rays. It was established that the tested actinomycete S. glaucus 71 MD produces silver nanoparticles extracellularly when acted upon by the silver nitrate solution, which offers a great advantage over an intracellular process of synthesis from the point of view of applications. The synthesis of silver nanoparticles by S. platensis proceeded differently under the short-term and long-term silver action. (author)

  19. Substoichiometric neutron activation determination of gold

    A highly precise and selective method is described for the determination of traces of gold by substoichiometric extraction from hydrochloric acid with tri-n-octylphosphine sulfide in cyclohexane following thermal neutron activation. Fundamental aspects of the extraction system are discussed and results are reported for the determination of gold in an effluent from a recovery process containing a complexed species of gold and unknown amounts of cyanide, citrate, phosphate, potassium and sodium. Other constituents of the effluent stream include traces of the transition elements Co, Ni, Fe, Cu, Zn, Pb and Sn at concentrations less than 50 ppm. One hour was allowed for the Au3+ carrier and the 198Au complexed species in samples and standards to oxidize, exchange, and reach chemical equilibrium. Samples were then equilibrated by shaking with the organic phase for thirty min. The percentage extractions (%E) for the substoichiometric separation of gold from the effluent and from the corresponding comparison standards were monitored. The mean percentage extractions for the substoichiometric separations of carrier from the effluent, and its corresponding standard were 75.3 and 59.3, respectively. These data are estimated to be accurate within +-2.0%. (T.G.)

  20. Chart of nuclides relating to neutron activation

    This chart is for frequent use in the prediction of the product species of neutron activation. The first edition of the chart has been made in 1976 after the repeated trial preparation. It has the following good points. (1) Any letter in chart is as large as one can read easily. [This condition has been obtained by the selection of items to be shown in chart. They are the name (the symbol of element, mass number, and half-life) of nuclide or of isomer, and the type of decay.]. (2) Decay product has been shown indirectly for branchings with two-step decay via short-lived daughter in an excited state. [This matter has been realized by use of the new mode of indication.] (3) Nuclides shown in chart are (a) naturally occurring nuclides and (b) nuclides formed from naturally occurring nuclides through one of the following reactions: (n, γ), (n, n'), (n, p), (n, α), (n, 2n), (n, pn), (n, 3n), (n, αn), (n, t), (n, 3He), (n, 2p), and (n, γ)(n, γ). In the revision of the first edition, some modes of indication have become a little simpler, and the isomers of shorter half-lives (0.1 - 1 μs) have been added. (author)

  1. Neutron-activation analysis of plant materials

    The possibilities offered by non-destructive neutron activation analysis (NAA) for simultaneously determining a large number of micro- and macro-components in plant samples of Bulgarian origin have been studied. Three groups of elements are determined: short half-life isotopes: Al, Mg, Ca, Na, Mn, Cl, Cu; medium half-life isotopes: Br, Na, K; and long half-life isotopes: Fe, Cr, Co, Sc, Pb, Zn. The samples are kept for 1 minute in a fluxes of 6x1012 n.cm2.sec-1 (first group), and of 3x1011 n.cm2.sec-1 for 18 hours (second and third groups). Use is made of a Ge/Li detector and 4000-channel analyser. To test the accuracy of the method, the results of NAA for some standard specimens have been compared with the indicators of other conventional methods tested in 18 laboratories in various countries. The data from NAA for the content of K, Mo, Ca, Mn, Fe, Zn and Cu demonstrate a high degree of coincidence with those from the other methods. Chemical composition of 23 samples of experimental and field crops is determined

  2. Active neutron multiplicity counting of bulk uranium

    This paper describes a new nondestructive assay technique being developed to assay bulk uranium containing kilogram quantities of 235U. The new technique uses neutron multiplicity analysis of data collected with a coincidence counter outfitted with AmLi neutron sources. We have calculated the expected neutron multiplicity count rate and assay precision for this technique and will report on its expected performance as a function of detector design characteristics, 235U sample mass, AmLi source strength, and source-to-sample coupling. 11 refs., 2 figs., 2 tabs

  3. The synchronous active neutron detection system for spent fuel assay

    The authors have begun to develop a novel technique for active neutron assay of fissile material in spent nuclear fuel. This approach will exploit the unique operating features of a 14-MeV neutron generator developed by Schlumberger. This generator and a novel detection system will be applied to the direct measurement of the fissile material content in spent fuel in place of the indirect measures used at present. The technique they are investigating is termed synchronous active neutron detection (SAND). It closely follows a method that has been used routinely in other branches of physics to detect very small signals in the presence of large backgrounds. Synchronous detection instruments are widely available commercially and are termed open-quotes lock-inclose quotes amplifiers. The authors have implemented a digital lock-in amplifier in conjunction with the Schlumberger neutron generator to explore the possibility of synchronous detection with active neutrons. This approach is possible because the Schlumberger system can operate at up to a 50% duty factor, in effect, a square wave of neutron yield. The results to date are preliminary but quite promising. The system is capable of resolving the fissile material contained in a small fraction of the fuel rods in a cold fuel assembly. It also appears to be quite resilient to background neutron interference. The interrogating neutrons appear to be nonthermal and penetrating. Although a significant amount of work remains to fully explore the relevant physics and optimize the instrument design, the underlying concept appears sound

  4. A dosimetry study of deuterium-deuterium neutron generator-based in vivo neutron activation analysis

    Sowers, Daniel A.

    A neutron irradiation cavity for in vivo Neutron Activation Analysis (IVNAA) to detect manganese, aluminum, and other potentially toxic elements in human hand bone has been designed and its dosimetric specifications measured. The neutron source is a customized deuterium-deuterium neutron generator which produces neutrons at 2.45 MeV by the fusion reaction 2H(d, n)3He at a calculated flux of 7 x 108 +/-30% s-1. A moderator/reflector/shielding (5 cm high density polyethylene (HDPE), 5.3 cm graphite & 5.7 cm borated HDPE) assembly has been designed and built to maximize the thermal neutron flux inside the hand irradiation cavity and to reduce the extremity dose and effective dose to the human subject. Lead sheets are used to attenuate bremsstrahlung x rays and activation gammas. A Monte Carlo simulation (MCNP6) was used to model the system and calculate extremity dose. The extremity dose was measured with neutron and photon sensitive film badges and Fuji electronic pocket dosimeter (EPD). The neutron ambient dose outside the shielding was measured by Fuji NSN3, and photon dose by a Bicron MicroREM scintillator. Neutron extremity dose was calculated to be 32.3 mSv using MCNP6 simulations given a 10 min IVNAA measurement of manganese. Measurements by EPD and film badge indicate hand dose to be 31.7 +/- 0.8 mSv for neutron and 4.2 +/- 0.2 mSv for photon for 10 mins; whole body effective dose was calculated conservatively to be 0.052 mSv. Experimental values closely match values obtained from MCNP6 simulations. These are acceptable doses to apply the technology for a manganese toxicity study in a human population.

  5. Determination of the Absolute Number of Cytokine mRNA Molecules within Individual Activated Human T Cells

    Karr, Laurel J.; Marshall, Gwen; Hockett, Richard D.; Bucy, R. Pat; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    A primary function of activated T cells is the expression and subsequent secretion of cytokines, which orchestrate the differentiation of other lymphocytes, modulate antigen presenting cell activity, and alter vascular endothelium to mediate an immune response. Since many features of immune regulation probably result from modest alterations of endogenous rates of multiple interacting processes, quantitative analysis of the frequency and specific activity of individual T cells is critically important. Using a coordinated set of quantitative methods, the absolute number of molecules of several key cytokine mRNA species in individual T cells has been determined. The frequency of human blood T cells activated in vitro by mitogens and recall protein antigens was determined by intracellular cytokine protein staining, in situ hybridization for cytokine mRNA, and by limiting dilution analysis for cytokine mRNA+ cells. The absolute number of mRNA molecules was simultaneously determined in both homogenates of the entire population of cells and in individual cells obtained by limiting dilution, using a quantitative, competitive RT-PCR assay. The absolute numbers of mRNA molecules in a population of cells divided by the frequency of individual positive cells, yielded essentially the same number of mRNA molecules per cell as direct analysis of individual cells by limiting dilution analysis. Mean numbers of mRNA per positive cell from both mitogen and antigen activated T cells, using these stimulation conditions, were 6000 for IL-2, 6300 for IFN-gamma, and 1600 for IL-4.

  6. Triton burnup measurements by neutron activation at JT-60U

    This paper describes measurements on triton burnup in a deuterium plasma by the detection of the 2.5 MeV neutrons (from DD fusion) and the 14 MeV neutrons (from DT fusion). The 2.5 MeV neutrons have been measured by fission chambers and activation of indium foils while the 14 MeV neutrons have been detected by activation of silicon, aluminum, and copper foils. The measured yields of the 2.5 MeV neutrons utilizing In foils are similar 20-40% higher than the yields obtained from fission chambers depending on what calibration factors are used. The deviation decreases with the plasma major radius (or increasing plasma volume). When the triton burnup is measured by utilizing neutron threshold reactions (En>2.5 MeV) and In foils, then systematic errors in the calibration factors cancel and the maximum deviation between the measured triton burnup for different calibration factors is reduced to similar 5%. The measurements indicate that triton burnup increases with the 14 MeV neutron yield, indicating that the relative yield of 14 MeV neutrons increases depending on the time duration of the deuterium neutral beam injection (NBI). Furthermore, the triton burnup decreases with an increased plasma major radius, indicating increased triton ripple losses, and increases with plasma current, indicating reduced banana orbit losses. (orig.)

  7. Neutron activation analysis of polyethylene from neutron shield of EDELWEISS experiment

    Rakhimov, Alimardon V. [Joint Institute for Nuclear Research (JINR), Dubna (Russian Federation); Uzbek Academy of Sciences (INP AS RUz), Tashkent (Uzbekistan). Inst. of Nuclear Physics; Brudanin, Viktor B.; Filosofov, Dmitry V. [Joint Institute for Nuclear Research (JINR), Dubna (Russian Federation); and others

    2015-07-01

    Instrumental neutron-activation analysis (INAA) was applied to estimate trace contaminations in polyethylene (PE) used as a neutron shield for low background setup of the EDELWEISS Dark Matter search experiment. PE samples with masses of 1-10 grams each were irradiated at the WWR-SM nuclear reactor by neutron flux of 1 x 10{sup 14}n/(cm{sup 2}s) for 5-48 h. The radioactivity was measured by high-resolution γ-ray spectrometry. In PE samples of two types, more than 30 trace elements were determined at a concentration level of 10{sup -5} to 10{sup -11} g/g.

  8. Simultaneous speciation analysis using neutron activation

    Full text: Neutron activation analysis (NAA) is a well-established analytical technique for the simultaneous determination of multielement concentrations. Although various forms of NAA have been traditionally applied to measuring the total concentrations of elements, the scope of NAA can be further extended in conjunction with pre-irradiation chemical separations to determine the species of an element. The technique can then be called speciation NAA (SNAA). Since much of the toxicity of an element depends on its physico-chemical forms, there is an increasing interest in studying its speciation. A number of characteristic features of NAA, which other techniques normally do not possess, can be advantageously exploited in SNAA. For example, SNAA has simultaneous multielement specificity unlike AAS and AFS. The SNAA technique can be applied to the simultaneous speciation of elements which are not chemically similar such as Cd, Se and I, as well as to the elements such as Cl, Br and I which are rather difficult to determine by most other techniques. Qualitative as well as quantitative analysis of small samples can be done by SNAA with excellent precision, accuracy, sensitivity, and rapidity. Unlike many other techniques, SNAA has some enhanced quality assurance capabilities. We have developed SNAA methods for separating various inorganic and organic arsenic species in water and in sea foods. We are presently extending these methods to include simultaneous speciation of As, Sb and Se. We have also developed SNAA methods employing biochemical techniques for the characterization of metalloproteins and protein-bound trace element species of Se along with Cd, Cu, Mn, Mo and Zn in bovine kidneys. Lately, we have concentrated our efforts to develop SNAA methods in conjunction with HPLC, RPC, SEC, NMR and MS for the simultaneous separation and characterization of extractable organo chlorine, organo bromine and organo iodine species in fisheries samples. An overview of the

  9. Diagnosis of mucoviscidosis by neutron activation analysis. Part 1

    Symptoms pathology, incidence, and gravity of the inherent syndrome called mucoviscidosis, or cystic fibrosis are described in this Part I. The analytical methods used for its diagnosis, both the conventional chemical ones and by neutron activation analysis are also summarised. Finally, an analytical method to study the incidence of mucoviscidosis in Brazil is presented. This , essentially, consists in bromine determination, in fingernails, by resonance neutron activation analysis. (author)

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

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

  11. The instrumental neutron activation determination of impurities in technical cobalt

    Instrumental neutron activation techniques for determination of 13 impurities with detection limit 10-5 - 10-2% in technical cobalt have been developed by using thermal and epithermal neutrons of nuclear reactor. Self-shielding and disturbance of neutron flux(Co59 has high capture cross-section of neutrons) by sample were taken into account by using some references and from the results obtained in preliminary experiments. Samples and standards have been placed in such a way that neutron flux disturbance was less than 2-3%. The Al-Pb-Cd-Cu filter was used for absorption of low energy γ-rays of Co60m and Co61. (author)

  12. Los Alamos second-generation system for passive and active neutron assays of drum-size containers

    We describe in a comprehensive fashion the Los Alamos second-generation system for passive and active neutron assays of drum-size containers. The developmental history of this 7-year project is presented with emphasis on the pulsed active neutron technique (differential dieaway), which has achieved milligram levels of assay sensitivity for both plutonium and uranium wastes. We describe in detail the matrix effects for both passive and active neutron assays. We present in a thorough fashion our novel approach to achieving comprehensive corrections for these matrix effects using measurements made during the assays. We develop a matrix correction formalism based on separate neutron absorption and moderator indices determined from these measurements. These are presented as a series of analytic functions fitted to the data. Absolute calibrations and calibration standards are discussed, as is a practical means (pink drum measurements) of achieving routine calibration verification at all implementation sites. We present our overall assay algorithm, integrating absolute calibrations with matrix corrections. We also present a systematic error formalism that is based on the matrix response data. Finally, we outline a strategy for the verification of our entire assay formalism. This is based on measurements with a set of salted waste matrix drums combined with systematic assay intercomparisons of well-characterized transuranic wastes

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

    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.

  14. Studying the measurement errors for the density of neutron beam from a reactor core by the gold foil activation method

    Applicability of the gold foil activation method for precise measurements of density of a neutron beam extracted from the reactor core is investigated experimentally. Comparison of density ratios of cold and hot beams is carried out to determine the error of measurements conducted with the use of gold foils and the detector with 6LiF target. Based on the analysis of the data obtained it is concluded that the total error of measurements using the activation method, comprising errors of determining cross section of gold activation Δσ=+-0.3% and absolute value of foil activity (also +- 0.3%) makes up +-0.7%

  15. Raw materials for low-activation concrete neutron shields

    Concrete surrounding a nuclear accumulates radioisotopes induced by neutron reactions during operation, and this concrete still remains to an enormous degree as radioactive waste after decommissioning. The disposal of such activated concrete is very costly and requires strict supervision. Hence, there has been a strong desire to develop a concrete that retains little residual radioactivity, that is, ''low-activation'' concrete. In the present study, we have identified several raw materials for such concrete - low-activation limestone, quartzite, colemanite, alumina-ceramics, while Portland cement and high-alumina cement - by performing a screening test for neutron irradiation. The results show that low-activation concrete compounded from such low-activation raw materials should serve for neutron shielding. Another noteworthy finding is that limestone occurring near schalstein deposits, and especially when sandwiched between two beds of schalstein, is an excellent low-activation raw material. (author)

  16. Development of a photonuclear activation file and measurement of delayed neutron spectra

    This thesis work consists in two parts. The first part is the description of the creation of a photonuclear activation file which will be used to calculated photonuclear activation. To build this file we have used different data sources: evaluations but also calculations done using several cross sections codes (HMS-ALICE, GNASH, ABLA). This file contains photonuclear activation cross sections for more than 600 nuclides and fission fragments distributions for 30 actinides at tree different Bremsstrahlung energies and the delay neutron spectrum associated. These spectra are not in good agreement with experimental data. That is why we decided to launch measurement of delayed neutrons spectra from photofission. The second part of this thesis consists in demonstrating the possibility to do such measurements at the ELSA accelerator facility. To that purpose, we have developed the detection, the acquisition system and the analysis method of such spectra. These were tested for the measurement of the delayed neutron spectrum of uranium-238 after irradiation in a 2 MeV neutron flux. Finally, we have measured the delayed neutron spectrum of uranium-238 after irradiation in a 15 MeV Bremsstrahlung flux. We compare our results with experimental data. The experiment has allowed us to improve the value of νp-bar with an absolute uncertainty below 7%, we propose νp-bar = (3.03 ± 0.02) n/100 fissions, and to correct the Nikotin's parameters for the six group representation. Particularly, we have improved the data concerning the sixth group by taking into account results from different irradiation times

  17. Beryllium neutron activation detector for pulsed DD fusion sources

    A compact fast neutron detector based on beryllium activation has been developed to perform accurate neutron fluence measurements on pulsed DD fusion sources. It is especially well suited to moderate repetition-rate (9Be(n,α)6He cross-section, energy calibration of the proportional counters, and numerical simulations of neutron interactions and beta-particle paths using MCNP5. The response function R(En) is determined over the neutron energy range 2-4 MeV. The count rate capability of the detector has been studied and the corrections required for high neutron fluence measurements are discussed. For pulsed DD neutron fluencies >3×104 cm-2, the statistical uncertainty in the fluence measurement is better than 1%. A small plasma focus device has been employed as a pulsed neutron source to test two of these new detectors, and their responses are found to be practically identical. Also the level of interfering activation is found to be sufficiently low as to be negligible.

  18. Elemental analysis of brazing alloy samples by neutron activation technique

    Two brazing alloy samples (C P2 and C P3) have been investigated by Neutron activation analysis (NAA) technique in order to identify and estimate their constituent elements. The pneumatic irradiation rabbit system (PIRS), installed at the first egyptian research reactor (ETRR-1) was used for short-time irradiation (30 s) with a thermal neutron flux of 1.6 x 1011 n/cm2/s in the reactor reflector, where the thermal to epithermal neutron flux ratio is 106. Long-time irradiation (48 hours) was performed at reactor core periphery with thermal neutron flux of 3.34 x 1012 n/cm2/s, and thermal to epithermal neutron flux ratio of 79. Activation by epithermal neutrons was taken into account for the (1/v) and resonance neutron absorption in both methods. A hyper pure germanium detection system was used for gamma-ray acquisitions. The concentration values of Al, Cr, Fe, Co, Cu, Zn, Se, Ag and Sb were estimated as percentages of the sample weight and compared with reported values. 1 tab

  19. Neutron activation analysis of wheat samples

    Galinha, C. [CERENA-IST, Technical University of Lisbon, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Instituto Tecnoclogico e Nuclear, URSN, E.N. 10, 2686-953 Sacavem (Portugal); Anawar, H.M. [Instituto Tecnoclogico e Nuclear, URSN, E.N. 10, 2686-953 Sacavem (Portugal); Freitas, M.C., E-mail: cfreitas@itn.pt [Instituto Tecnoclogico e Nuclear, URSN, E.N. 10, 2686-953 Sacavem (Portugal); Pacheco, A.M.G. [CERENA-IST, Technical University of Lisbon, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Almeida-Silva, M. [Instituto Tecnoclogico e Nuclear, URSN, E.N. 10, 2686-953 Sacavem (Portugal); Coutinho, J.; Macas, B.; Almeida, A.S. [INRB/INIA-Elvas, National Institute of Biological Resources, Est. Gil Vaz, 7350-228 Elvas (Portugal)

    2011-11-15

    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. (Jordao/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 26,400-31,300 mg/kg, respectively, were relatively high, but Zn concentration was very low (below detection limit <22 mg/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 (4-30 mg/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

  20. Neutron activation analysis of wheat samples

    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. (Jordao/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 26,400-31,300 mg/kg, respectively, were relatively high, but Zn concentration was very low (below detection limit 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 (4-30 mg/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, Jordao presented higher transfer coefficients than Marialva, in particular for Co, Fe, and Na. The Jordao and Marialva cultivars accumulated not statistically significant different

  1. Specialized database for instrumental neutron activation analysis-ND INAA 1.0

    Full text: In order to conduct nuclear and physical elemental analysis of materials content, in particular, activation analysis it is necessary to attract a large number of various nuclear data. The network of nuclear data centers (NNDC) under supervision of IAEA is dealing with accumulation, evaluation and systematization of nuclear data. The authors of the work have developed a software and information medium consisting specialized database, a package of calculation as well as requests and results visualization software. Based on evaluated nuclear data and original works a specialized database for need of neutron-activation analysis - ND INAA 1.0 was developed. The database presents a relatively frequently encountered isotopes of elements, thermal and resonance neutrons rapping cross-sections, decay types, radionuclides half-life, gamma- and alpha-radiation energies and intensities, maximal energies and intensities of beta-radiation, gamma-constants, and absolute yields of KX-radiation of radioactive nuclides, radioactive chains. The report contains examples of use of ND INAA 1.0 database along with the database on elemental content of natural objects - ELEMENT [1]: calculation of macro-cross-sections of elemental activation and calculation of activity of produced isotope on thermal and resonance neutrons in investigated objects, with taking into account of saturation and decay factors, geochemical spectra and others. Necessary calculations are conducted both for single radionuclide and for natural object as a whole. Separate part is dedicated to automation of K-Ar geological objects dating method. The give database is a part of developed by authors the system of automatization of instrumental neutron activation analysis - INAA. The developed apparatus allows one to use the given software production for another modifications of activation analysis. This work is performed on the project P-20-48 CST RUz

  2. Research and development activities of a neutron generator facility

    The neutron generator facility at YNRC is used for elemental analysis, nuclear data measurement and education. In nuclear data measurement the focus is on re-evaluating the existing scattered nuclear activation cross-section to obtain systematic data for nuclear reactions such as (n,p), (n,α), and (n,2n). In elemental analysis it is used for analyzing the Nitrogen (N), Phosphor (P) and Potassium (K) contents in chemical and natural fertilizers (compost), protein in rice, soybean, and corn and pollution level in rivers. The neutron generator is also used for education and training of BATAN staff and university students. The facility can also produce neutron generator components. (author)

  3. Design and construction of a cryogenic facility providing absolute measurements of radon 222 activity for developing a primary standard

    Radon 222 metrology is required to obtain higher accuracy in assessing human health risks from exposure to natural radiation. This paper describes the development of a cryogenic facility that allows absolute measurements of radon 222 in order to obtain a primary standard. The method selected is the condensation of a radon 222 sample on a geometrically defined cold surface with a constant, well known and adjustable temperature and facing an alpha particles detector. Counting of the alpha particles reaching the detector and the precisely known detection geometry provide an absolute measurement of the source activity. After describing the cryogenic facility, the measurement accuracy and precision are discussed and a comparison made with other measurement systems. The relative uncertainty is below 1 pc (1 σ). The facility can also be used to improve our knowledge of the nuclear properties of radon 222 and to produce secondary standards. (author)

  4. Time, absolute.

    Mughal, Muhammad Aurang Zeb

    2009-01-01

    The concept of absolute time is a hypothetical model from the laws of classical physics postulated by Isaac Newton in the Principia in 1687. Although the Newtonian model of absolute time has since been opposed and rejected in light of more recent scholarship, it still provides a way to study science with reference to time and understand the phenomena of time within the scientific tradition. According to this model, it is assumed that time runs at the same rate for all the observers in the uni...

  5. Background by neutron activation in GERDA

    The observation of the neutrinoless double beta decay is a proof of the Majorana nature of the neutrino. The long half-life of this decay requires experiments of very low background rates in the region of interest at Qββ. Prompt γ-rays after neutron capture on germanium and the β-decay of 77Ge contribute to the background in experiments using 76Ge for the search of the neutrinoless double beta decay. The poorly known prompt γ-ray spectra and the neutron capture cross sections for the (n,γ) reactions of 74Ge and 76Ge were measured at the research reactor FRM II (Munich). The obtained data are needed in MC simulations for qualitative and quantitative background prediction in the Gerda experiment. The data and their implication on the background in Gerda are presented.

  6. Interpretation of active neutron measurements by the heterogeneous theory

    In this paper are presented results from a study on the application of the heterogeneous method for the interpretation of active neutron measurements. The considered apparatus consists out of a cylindrical lead pile, which is provided with two axial channels: a central channel incorporates an antimony beryllium photoneutron source and an excentric channel serves for the insertion of the sample to be assayed for fissionable materials contents. The mathematical model of this apparatus is the heterogeneous group diffusion theory. Sample and source channel are described by multigroup monopolar and dipolar sources and sinks. Monopolar sources take account of neutron production within energy group and in-scatter from upper groups. Monopolar sinks represent neutron removal by absorption within energy group and outscatter to lower groups. Dipol sources describe radial streaming of neutrons across the sample channel. Multigroup diffusion theory is applied throughout the lead pile. The strengths of the monopolar and dipolar sources and sinks are determined by linear extrapolation distances of azimuthal mean and first harmonic flux values at the channels' surface. In an experiment we may measure the neutrons leaking out of the lead pile and linear extrapolation distances at the channels' surface. Such informations are utilized for interpretation in terms of fission neutron source strengh and mean neutron flux values in the sample. In this paper we summarized the theoretical work in course

  7. Evaluation of new pharmaceuticals using in vivo neutron inelastic scattering and neutron activation analysis

    Nutritional status of patients can be evaluated by monitoring changes in body composition, including depletion of protein and muscle, adipose tissue distribution and changes in hydration status, bone or cell mass. Fast neutron activation (for N and P) and neutron inelastic scattering (for C and O) are used to assess in vivo elements characteristic of specific body compartments. The fast neutrons are produced with a sealed deuterium-tritium (D-T) neutron generator. This method provides the most direct assessment of body composition. Non-bone phosphorus for muscle is measured by the 31P(n,α)28Al reaction, and nitrogen for protein via the (n,2n) fast neutron reaction. Inelastic neutron scattering is used for the measurement of total body carbon and oxygen. Carbon is used to derive body fat, after subtracting carbon contributions due to protein, bone and glycogen. Carbon-to-oxygen (C/O) ratio is used to measure distribution of fat and lean tissue in the body and to monitor small changes of lean mass and its quality. In addition to evaluating the efficacy of new treatments, the system is used to study the mechanisms of lean tissue depletion with aging and to investigate methods for preserving function and quality of life in the elderly. (author)

  8. Development of cylindrical type proton-recoil proportional counter and its use for absolute measurements of neutron fluences at 144, 250 and 565 keV monoenergetic calibration fields

    A proton-recoil proportional counter has been developed as a standard instrument for measuring neutron fluence at an accelerator-based neutron calibration field. The counter consists of a cylindrical cathode and an external housing in which hydrogen is filled as counting gas. For neutrons in the energy range between 50 keV and 1 MeV, the fluence of the neutron field can be determined by an absolute measurement with the counter. In designing and manufacturing the counter, careful attention has been paid in order to reduce the uncertainty in measured results. For example, the volume of the effective region of the counter was investigated as accurately as possible. The optimum applied voltage for the counter was examined precisely through the electric field analysis. The developed counter was used for determining the reference neutron fluence of the monoenergetic neutron fields at the Facility of Radiation Standards of JAEA. For the 144, 250 and 565 keV neutron fields, it has been able to measure the fluences with the standard uncertainties less than 2%. The measured fluences for 144 and 565 keV have showed good agreement with the values estimated by another measurements with a transfer instrument traceable to primary standards. (author)

  9. [Absolute bioavailability of the adenine derivative VMA-99-82 possessing antiviral activity].

    Smirnova, L A; Suchkov, E A; Riabukha, A F; Kuznetsov, K A; Ozerov, A A

    2013-01-01

    Investigation of the main pharmacokinetic parameters of adenine derivative VMA-99-82 in rats showed large values of the half-life (T1/2 = 11.03 h) and the mean retention time of drug molecules in the organism (MRT = 9.53 h). A high rate of the drug concentration decrease in the plasma determines a small value of the area under the pharmacokinetic curve (AUC = 74.96 mg h/ml). The total distribution volume (V(d) = 10.61 l/kg) is 15.8 times greater than the volume of extracellular fluid in the body of rat, which is indicative of a high ability of VMA-99-82 to be distributed and accumulated in the organs and tissues. The absolute bioavailability of VMA-99-82 is 66%. PMID:24605425

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

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

    2011-01-01

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